JP7725904B2 - Toner and its manufacturing method, toner storage unit, image forming apparatus, and image forming method - Google Patents

Description

The present invention relates to toner and its manufacturing method, a toner storage unit, an image forming apparatus, and an image forming method.

Toner is required to have small particle size and high-temperature offset resistance to improve the quality of output images, low-temperature fixability to save energy, and heat-resistant storage properties that can withstand the high temperatures and humidity experienced during storage and transportation after production. Since the power consumed during fixation accounts for a large portion of the power consumed in the image formation process, improving low-temperature fixability is particularly important.

In recent years, in order to obtain a toner that can achieve both low-temperature fixability and heat-resistant storage stability, a method for producing composite resin particles has been proposed, which includes a step of forming composite resin particles in which resin fine particles containing two types of resin as constituent components within the same particle are attached to the surface of the resin fine particles, and then removing part or all of the resin from the resin fine particles (see, for example, Patent Documents 1 and 2).
Furthermore, in order to obtain a toner that has high heat-resistant storage stability and can suppress toner aggregation even when used for a long period of time, a toner has been proposed in which a core layer contains a styrene acrylic modified polyester resin and is coated with spherical particles for a shell that are covered with a styrene acrylic resin component (see, for example, Patent Document 3).

In addition, a toner containing a crystalline resin and silicone oil-treated silica particles with an average primary particle size of 50 nm to 150 nm has been proposed, with the aim of obtaining a toner that can maintain low-temperature fixability while preventing image defects and forming stable images over the long term by using wet-process silica, which can be controlled to a particle size larger than that of dry-process silica, and thereby preventing contact between toner particles and maintaining low-temperature fixability while preventing image defects (see, for example, Patent Document 4).

Furthermore, toner containing non-spherical silica as an external additive has been proposed to prevent silica from being liberated due to friction between toner particles or from being embedded in the toner surface (see, for example, Patent Document 5). The invention described in Patent Document 5 increases the contact area between the external additive and the toner matrix, thereby preventing the external additive from being liberated or embedded due to friction between toner particles or between the toner and carrier.

The object of the present invention is to provide a toner that suppresses the occurrence of abnormal images caused by filming, while also achieving high levels of low-temperature fixability and excellent cleanability due to low adhesion.

The toner of the present invention, which is a means for solving the above problems, is a toner having a plurality of resin fine particles on the surface of toner base particles as observed with a scanning electron microscope (SEM), and is characterized in that the toner contains at least a resin and a wax, and when the resin fine particles having a major axis of 3R or more are aggregated, where R is the major axis of the smallest particle among the resin fine particles, the proportion of the surface of the toner base particles occupied by the aggregate is 15% or more and 60% or less.

This invention makes it possible to provide a toner that suppresses the occurrence of abnormal images caused by filming, while also achieving high levels of low-temperature fixability and excellent cleanability due to low adhesion.

FIG. 1 is a schematic diagram showing an example of the state of the toner surface. FIG. 2 is a schematic view showing an example of the process cartridge of the present invention. FIG. 3 is a schematic diagram showing an example of the image forming apparatus of the present invention.

(toner)
The present invention provides a toner having a plurality of resin fine particles on the surface of a toner base particle, as observed by a scanning electron microscope (SEM), the toner containing at least a resin and a wax, and when the resin fine particles having a major axis of 3R or more are aggregated, where R is the major axis of the smallest particle among the resin fine particles, the proportion of the aggregate occupying the surface of the toner base particle is 15% or more and 60% or less, and further containing another component (A) as necessary.
In the present invention, particles in which the resin fine particles are present on the surface of the toner base particles may be referred to as composite particles.

Generally, to improve the low-temperature fixability of a toner, it is necessary to use a material with a low melting point in the toner. However, toner produced using a material with a low melting point has poor heat-resistant storage stability and adhesion, so there is a trade-off between low-temperature fixability and heat-resistant storage stability and adhesion.

The conventional techniques described in Patent Documents 1 to 3 have a problem that cleaning failure due to deterioration of adhesive strength is not sufficiently resolved in toners with excellent low-temperature fixability. Therefore, when even better low-temperature fixability is required, a means for resolving the contradictory adhesive strength is required.
The conventional technology described in Patent Document 3 (JP 2013-011644 A) has a problem in that the shell layer inhibits heat transfer from the fixing roller, making it impossible to obtain sufficient low-temperature fixability.

In the conventional technology described in Patent Document 4 (JP 2009-098194 A), small particle diameter external additives (for example, silica) added to the surface of toner particles are detached from the toner and adhere to the photoreceptor, and then these particles aggregate and densify to form strongly adhered silica, which causes the problem of abnormal images due to so-called filming.
Furthermore, the particle size range of the external additive in the conventional technology described in Patent Document 4 includes silica with a large particle size of 120 nm to 150 nm, which causes a problem of silica liberation and makes images prone to abnormalities. Furthermore, with the conventional toner, silica is prone to liberation due to friction between toner particles, which raises concerns about the occurrence of image defects such as filming and blurred images.
In order to prevent the external additives from separating, it is necessary to firmly attach the external additives to the surface of the toner base particles using a strong force from a mixer, which results in some areas where the external additives are buried, making it difficult to achieve the desired effect.

Therefore, the fundamental cause of filming is the separation of external additives (such as silica) attached to the surface of toner base particles. Since there is a trade-off between the low-temperature fixability required of toner properties, and adhesion and heat-resistant storage stability, it is difficult to satisfy all of these qualities.

After extensive research, the inventors discovered that by having aggregates made of resin fine particles present on the surface of the toner base particles and by setting the proportion of these aggregates on the toner base particle surface to between 15% and 60%, it is possible to position an appropriate amount of aggregates on the surface of the toner base particles, thereby optimizing the amount of free external additive, suppressing the occurrence of filming, and achieving high levels of both low-temperature fixability and excellent cleanability due to low adhesion.

Therefore, in this invention, a toner has a plurality of resin microparticles on the surface of toner base particles as observed with a scanning electron microscope (SEM), the toner containing at least a resin and a wax, and when the resin microparticles are aggregated and have a major axis of 3R or more, where R is the major axis of the smallest particle among the resin microparticles, the proportion of the aggregates occupying the surface of the toner base particles is 15% or more and 60% or less, thereby suppressing the occurrence of filming and achieving high levels of both low-temperature fixability and excellent cleanability due to low adhesion.

<Resin fine particles>
The resin fine particles and the aggregates formed from the resin fine particles in the present invention are present on the surface of the toner base particles, which will be described later.

The resin microparticles preferably have a core resin (core portion) and a shell resin (outer shell portion) that covers at least a portion of the surface of the core resin, more preferably consist of the core resin and the shell resin, and even more preferably contain a vinyl-based unit consisting of the core resin and the shell resin.
The shell resin and the core resin preferably contain a polymer obtained by homopolymerizing or copolymerizing a vinyl monomer, and the shell resin preferably contains a styrene-acrylic resin.
In the present invention, the shell resin may be referred to as "resin (b1)" and the core resin may be referred to as "resin (b2)".
In the present invention, particles containing the resin (b1) and the resin (b2) as constituent components within the same particle may be referred to as "resin fine particles (B)".

The vinyl monomer is not particularly limited and can be selected appropriately depending on the purpose. Examples include (1) to (10) shown below.

(1) Vinyl Hydrocarbons Examples of the vinyl hydrocarbons include (1-1) aliphatic vinyl hydrocarbons, (1-2) alicyclic vinyl hydrocarbons, and (1-3) aromatic vinyl hydrocarbons.

(1-1) Aliphatic Vinyl Hydrocarbons Examples of the aliphatic vinyl hydrocarbons include alkenes and alkadienes.
Specific examples of the alkene include ethylene, propylene, and α-olefins.
Specific examples of the alkadienes include butadiene, isoprene, 1,4-pentadiene, 1,6-hexadiene, and 1,7-octadiene.

(1-2) Alicyclic Vinyl Hydrocarbons Examples of the alicyclic vinyl hydrocarbons include monocycloalkenes, dicycloalkenes, and alkadienes.
Specific examples of the alicyclic vinyl hydrocarbon include (di)cyclopentadiene and terpene.

(1-3) Aromatic Vinyl Hydrocarbons Examples of the aromatic vinyl hydrocarbons include styrene and its hydrocarbyl (alkyl, cycloalkyl, aralkyl and/or alkenyl) substituted products.
Specific examples of the aromatic vinyl hydrocarbon include α-methylstyrene, 2,4-dimethylstyrene, and vinylnaphthalene.

(2) Carboxyl Group-Containing Vinyl Monomers and Salts Thereof Examples of the carboxyl group-containing vinyl monomers and salts thereof include unsaturated monocarboxylic acids (salts), unsaturated dicarboxylic acids (salts), and anhydrides (salts) thereof, each having 3 to 30 carbon atoms, as well as monoalkyl (having 1 to 24 carbon atoms) esters thereof or salts thereof.
Specific examples of the carboxyl group-containing vinyl monomer and salts thereof include carboxyl group-containing vinyl monomers such as (meth)acrylic acid, maleic acid (anhydride), maleic acid monoalkyl esters, fumaric acid, fumaric acid monoalkyl esters, crotonic acid, itaconic acid, itaconic acid monoalkyl esters, itaconic acid glycol monoether, citraconic acid, citraconic acid monoalkyl esters, and cinnamic acid, and metal salts thereof.

In the present invention, the term "(salt)" means an acid or a salt thereof.
For example, an unsaturated monocarboxylic acid (salt) having 3 to 30 carbon atoms means an unsaturated monocarboxylic acid or a salt thereof.
In the present invention, "(meth)acrylic" means methacrylic acid or acrylic acid.
In the present invention, "(meth)acryloyl" means methacryloyl or acryloyl.
In the present invention, "(meth)acrylate" means methacrylate or acrylate.

(3) Sulfone Group-Containing Vinyl Monomers, Vinyl Sulfate Monoesters, and Salts Thereof Examples of the sulfone group-containing vinyl monomers, vinyl sulfate monoesters, and salts thereof include C2-C14 alkene sulfonic acids (salts), C2-C24 alkyl sulfonic acids (salts), sulfo(hydroxy)alkyl-(meth)acrylates (salts) or (meth)acrylamides (salts), and alkylallylsulfosuccinic acids (salts).
Specific examples of the alkene sulfonic acid (salt) having 2 to 14 carbon atoms include vinyl sulfonic acid (salt).
Specific examples of the alkylsulfonic acid (salt) having 2 to 24 carbon atoms include α-methylstyrenesulfonic acid (salt).
Specific examples of the sulfo(hydroxy)alkyl-(meth)acrylate (salt) or (meth)acrylamide (salt) include sulfopropyl(meth)acrylate (salt), sulfuric acid ester (salt), and sulfonic acid group-containing vinyl monomer (salt).

(4) Phosphate Group-Containing Vinyl Monomers and Salts Thereof Examples of the phosphate group-containing vinyl monomers and salts thereof include (meth)acryloyloxyalkyl (C1 to C24) phosphate monoesters (salts) and (meth)acryloyloxyalkyl (C1 to C24) phosphonic acids (salts).
Specific examples of the (meth)acryloyloxyalkyl (having 1 to 24 carbon atoms) phosphate monoester (salt) include 2-hydroxyethyl (meth)acryloyl phosphate (salt), phenyl-2-acryloyloxyethyl phosphate (salt), and the like.
Specific examples of the (meth)acryloyloxyalkyl (carbon number 1 to 24) phosphonic acid (salt) include 2-acryloyloxyethyl phosphonic acid (salt).

Examples of salts of the (2) carboxyl group-containing vinyl monomer, the (3) sulfone group-containing vinyl monomer and vinyl sulfate monoester, and the (4) phosphate group-containing vinyl monomer include alkali metal salts (sodium salt, potassium salt, etc.), alkaline earth metal salts (calcium salt, magnesium salt, etc.), ammonium salts, amine salts, and quaternary ammonium salts.

(5) Hydroxyl Group-Containing Vinyl Monomers Examples of the hydroxyl group-containing vinyl monomers include hydroxystyrene, N-methylol(meth)acrylamide, hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, polyethylene glycol mono(meth)acrylate, (meth)allyl alcohol, crotyl alcohol, isocrotyl alcohol, 1-buten-3-ol, 2-buten-1-ol, 2-butene-1,4-diol, propargyl alcohol, 2-hydroxyethylpropenyl ether, and sucrose allyl ether.

(6) Nitrogen-Containing Vinyl Monomers Examples of the nitrogen-containing vinyl monomers include (6-1) amino group-containing vinyl monomers, (6-2) amide group-containing vinyl monomers, (6-3) nitrile group-containing vinyl monomers, (6-4) quaternary ammonium cation group-containing vinyl monomers, and (6-5) nitro group-containing vinyl monomers.

(6-1) Amino Group-Containing Vinyl Monomers Examples of the amino group-containing vinyl monomers include aminoethyl (meth)acrylate.

(6-2) Amide Group-Containing Vinyl Monomers Examples of the amide group-containing vinyl monomers include (meth)acrylamide and N-methyl(meth)acrylamide.

(6-3) Nitrile Group-Containing Vinyl Monomers Examples of the nitrile group-containing vinyl monomers include (meth)acrylonitrile, cyanostyrene, and cyanoacrylate.

(6-4) Quaternary Ammonium Cation Group-Containing Vinyl Monomer Examples of the quaternary ammonium cation group-containing vinyl monomer include quaternized products of tertiary amine group-containing vinyl monomers such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylamide, diethylaminoethyl (meth)acrylamide, and diallylamine (which are quaternized using a quaternizing agent such as methyl chloride, dimethyl sulfate, benzyl chloride, or dimethyl carbonate).

(6-5) Nitro Group-Containing Vinyl Monomers Examples of the nitro group-containing vinyl monomers include nitrostyrene.

(7) Epoxy Group-Containing Vinyl Monomers Examples of the epoxy group-containing vinyl monomers include glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and p-vinylphenyl phenyloxide.

(8) Halogen-Containing Vinyl Monomers Examples of the halogen-containing vinyl monomers include vinyl chloride, vinyl bromide, vinylidene chloride, allyl chloride, chlorostyrene, bromostyrene, dichlorostyrene, chloromethylstyrene, tetrafluorostyrene, and chloroprene.

(9) Vinyl esters, vinyl (thio) ethers, vinyl ketones Examples of the vinyl esters include vinyl acetate, vinyl butyrate, vinyl propionate, vinyl butyrate, diallyl phthalate, diallyl adipate, isopropenyl acetate, vinyl methacrylate, methyl 4-vinyl benzoate, cyclohexyl methacrylate, benzyl methacrylate, phenyl (meth)acrylate, vinyl methoxyacetate, vinyl benzoate, ethyl α-ethoxyacrylate, alkyl (meth)acrylates having an alkyl group of 1 to 50 carbon atoms [methyl ( (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, eicosyl (meth)acrylate, behenyl (meth)acrylate, etc.)], dialkyl fumarate (wherein the two alkyl groups have 2 to 8 carbon atoms and are linear, branched, or alicyclic groups), dialkyl Examples of the alkyl maleate include alkyl maleates (the two alkyl groups each having 2 to 8 carbon atoms and being a straight-chain, branched-chain, or alicyclic group), poly(meth)allyloxyalkanes (diallyloxyethane, triallyloxyethane, tetraallyloxyethane, tetraallyloxypropane, tetraallyloxybutane, tetramethallyloxyethane, etc.), vinyl monomers having a polyalkylene glycol chain (polyethylene glycol (molecular weight 300) mono(meth)acrylate, polypropylene glycol (molecular weight 500) monoacrylate, methyl alcohol ethylene oxide 10 mol adduct (meth)acrylate, lauryl alcohol ethylene oxide 30 mol adduct (meth)acrylate, etc.), and poly(meth)acrylates (poly(meth)acrylates of polyhydric alcohols: ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, polyethylene glycol di(meth)acrylate, etc.).
Examples of the vinyl (thio)ether include vinyl methyl ether.
Examples of the vinyl ketone include vinyl methyl ketone.

(10) Other Vinyl Monomers Examples of the other vinyl monomers include tetrafluoroethylene, fluoroacrylate, isocyanatoethyl (meth)acrylate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate.

In synthesizing the resin (b1), the vinyl monomers (1) to (10) may be used alone or in combination of two or more.
The resin (b1) is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of low-temperature fixability, however, a styrene-(meth)acrylic acid ester copolymer and a (meth)acrylic acid ester copolymer are more preferable, and a styrene-(meth)acrylic acid ester copolymer is even more preferable.
When the resin (b1) contains a carboxylic acid, an acid value can be imparted to the resin, and it becomes easier to form a toner having the resin fine particles (B) on the surface of the toner base particles described later.

In synthesizing the resin (b2), the vinyl monomers (1) to (10) listed for the resin (b1) may be used alone or in combination of two or more.
The resin (b2) is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of low-temperature fixability, however, a styrene-(meth)acrylic acid ester copolymer and a (meth)acrylic acid ester copolymer are preferred, and a styrene-(meth)acrylic acid ester copolymer is more preferred.

The loss modulus G″ of the viscoelastic properties of the resin (b1) at a frequency of 1 Hz and 100° C. is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1.5 MPa to 100 MPa, more preferably 1.7 MPa to 30 MPa, and even more preferably 2.0 MPa to 10 MPa.
The loss modulus G″ of the viscoelastic properties of the resin (b2) at a frequency of 1 Hz and 100° C. is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.01 MPa to 1.0 MPa, more preferably 0.02 MPa to 0.5 MPa, and even more preferably 0.05 MPa to 0.3 MPa.
When the loss modulus G″ of the viscoelastic properties of the resin (b1) and the resin (b2) is within the above range, it becomes easy to form a toner having the resin fine particles (B) on the surface of the toner base particles described later.

The loss modulus G″ of the viscoelastic properties in the present invention is measured, for example, using a viscoelasticity measuring device (ARES-24A (manufactured by Rheometrics)) under the following conditions.
-Measurement conditions-
Jig: 25mm parallel plate Frequency: 1Hz
Distortion rate: 10%
Temperature increase rate: 5°C/min

The loss modulus G″ of the viscoelastic properties of the resin (b1) and the resin (b2) at a frequency of 1 Hz and 100°C can be adjusted within the above-mentioned range by adjusting the types and composition ratio of the constituent monomers and the polymerization conditions (types and amounts of initiator and chain transfer agent, reaction temperature, etc.).
Specific examples of the method for adjusting the loss modulus G″ of the viscoelastic properties include (i) adjusting the glass transition temperature (Tg), and (ii) adjusting the calculated acid value (AV).

(i) Adjustment of Glass Transition Temperature (Tg) In this specification, the glass transition temperature calculated from the constituent monomers of the resin (b1) is referred to as (Tg1), and the glass transition temperature calculated from the constituent monomers of the resin (b2) is referred to as (Tg2).
The glass transition temperature (Tg1) is preferably from 0°C to 150°C, and more preferably from 50°C to 100°C.
A glass transition temperature (Tg1) of 0° C. or higher is preferable because a toner having excellent heat resistance and storage stability can be obtained. A glass transition temperature (Tg1) of 150° C. or lower is preferable because the toner is less susceptible to heat conduction during fixing.
The glass transition temperature (Tg2) is preferably from -30°C to 100°C, more preferably from 0°C to 80°C, and even more preferably from 30°C to 60°C.
When the glass transition temperature (Tg2) is −30° C. or higher, a toner having excellent heat resistance and storage stability can be obtained. When the glass transition temperature (Tg2) is 100° C. or lower, the toner is preferably less susceptible to heat conduction during fixing.

The (Tg1) is preferably higher than the (Tg2), more preferably 10°C or more higher than the (Tg2), and even more preferably 20°C or more higher than the (Tg2). Doing so makes it easier to form a toner having the resin fine particles (B) on the surface of the toner base particles described below, and is also advantageous because it allows for the production of a toner that exhibits excellent low-temperature fixability.

The glass transition temperature (Tg) calculated from the constituent monomers of the resin is a value that can be calculated by the Fox method.
Here, the Fox method [T. G. Fox, Phys. Rev., 86, 652 (1952)] is a method for estimating the Tg of a copolymer from the Tg of each homopolymer, as shown in the following (Equation 1):
1/Tg=W1/Tg1+W2/Tg2+...+Wn/Tgn (Formula 1)
(In formula 1, Tg represents the glass transition temperature (expressed in absolute temperature) of the copolymer, Tg1, Tg2, ... Tgn represent the glass transition temperatures (expressed in absolute temperature) of the homopolymers of each monomer component, and W1, W2, ... Wn represent the weight fraction of each monomer component.)
The glass transition temperature (Tg) can be measured by the method (DSC) specified in ASTM D3418-82 using a "DSC20, SSC/580" (manufactured by Seiko Instruments Inc.).

(ii) Preparation of Calculated Acid Value (AV) In this specification, the calculated acid value of the resin (b1) is referred to as (AV1), and the calculated acid value of the resin (b2) is referred to as (AV2).
The (AV1) is preferably 75 mgKOH/g to 400 mgKOH/g, and more preferably 150 mgKOH/g to 300 mgKOH/g.
The (AV2) is preferably 0 mgKOH/g to 50 mgKOH/g, more preferably 0 mgKOH/g to 20 mgKOH/g, and even more preferably 0 mgKOH/g, in order to obtain a toner that exhibits excellent low-temperature fixing properties.
When the (AV1) is 75 mgKOH/g or more and 400 mgKOH/g or less and the (AV2) is 0 mgKOH/g or more and 50 mgKOH/g or less, it is preferable because it is easy to form a toner having the resin fine particles (B) on the surface of the toner base particles described later.
The calculated acid value is a theoretical acid value calculated from the molar amount of acidic groups contained in the constituent monomers and the total weight of the constituent monomers.
The method for measuring the acid value in the present invention is not particularly limited and can be appropriately selected depending on the purpose. For example, the acid value can be measured by the method of JIS K0070:1992.

Examples of the resin (b1) that satisfies the conditions (i) and (ii) include a resin that contains, as a constituent monomer, preferably 10% by mass to 80% by mass, more preferably 30% by mass to 60% by mass of styrene, and preferably a total of 10% by mass to 60% by mass, more preferably a total of 30% by mass to 50% by mass of methacrylic acid and/or acrylic acid, based on the total mass of the resin (b1), from the viewpoint of (Tg1) and copolymerizability with other monomers.
Examples of the resin (b2) that satisfies the conditions (i) and (ii) include a resin that contains, as a constituent monomer, preferably 10% by mass to 100% by mass, more preferably 30% by mass to 90% by mass of styrene, and preferably 0% by mass to 7.5% by mass in total, more preferably 0% by mass to 2.5% by mass of methacrylic acid and/or acrylic acid, based on the total mass of the resin (b2), from the viewpoint of (Tg2) and copolymerizability with other monomers.

From the viewpoint of ease of forming toner particles, the solubility parameter (hereinafter sometimes abbreviated as SP value) of the resin (b1) is preferably 9 (cal/cm ³ ) ^1/2 to 13 (cal/cm ³ ) ^1/2 , more preferably 9.5 (cal/cm ³ ) ^1/2 to 12.5 (cal/cm ³ ) ^1/2 , and even more preferably 10.5 (cal/cm ³ ) ^1/2 to 11.5 (cal/cm ³ ) ^1/2 .
From the viewpoint of ease of forming toner particles, the SP value of the resin (b2) is preferably 8.5 (cal/cm ³ ) ^1/2 to 12.5 (cal/cm ³ ) ^1/2 , more preferably 9 (cal/cm ³ ) ^1/2 to 12 (cal/cm ³ ) ^1/2 , and even more preferably 10 (cal/cm ³ ) ^1/2 to 11 (cal/cm ³ ) ^1/2 .
The SP values of the resin (b1) and the resin (b2) can be adjusted by changing the types of constituent monomers and the constituent ratio thereof.
The SP value in the present invention can be calculated by the method by Fedors [Polym. Eng. Sci. 14(2)152, (1974)].

The number average molecular weight (Mn1) of the resin (b1) is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 2,000 to 2,000,000, and more preferably 20,000 to 200,000. If the number average molecular weight (Mn1) is 2,000 or more, the heat-resistant storage stability is improved, and if it is 2,000,000 or less, it is preferable because the low-temperature fixability of the toner is less hindered.
The number average molecular weight (Mn2) of the resin (b2) is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1,000 to 1,000,000, and more preferably 10,000 to 100,000. If the number average molecular weight (Mn2) is 1,000 or more, the heat-resistant storage stability of the toner is improved, and if it is 1,000,000 or less, it is preferable because the low-temperature fixability of the toner is less hindered.

The weight average molecular weight (Mw1) of the resin (b1) is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 20,000 to 20,000,000, and more preferably 200,000 to 2,000,000. If the weight average molecular weight (Mw1) is 20,000 or more, the heat-resistant storage stability of the toner is improved, and if it is 20,000,000 or less, it is preferable because the low-temperature fixability of the toner is less hindered.
The weight average molecular weight (Mw2) of the resin (b2) is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10,000 to 10,000,000, and more preferably 100,000 to 1,000,000. If the weight average molecular weight (Mw2) is 10,000 or more, the heat-resistant storage stability of the toner is improved, and if it is 10,000,000 or less, it is preferable because the low-temperature fixability of the toner is less hindered.

The weight average molecular weight (Mw1) of the resin (b1) is preferably larger than the weight average molecular weight (Mw2) of the resin (b2), more preferably at least 1.5 times larger than the weight average molecular weight (Mw2) of the resin (b2), and even more preferably at least 2.0 times larger than the weight average molecular weight (Mw2) of the resin (b2). When the (Mw1) is within the above range, it becomes easier to form a toner having the resin fine particles (B) on the surface of the toner base particles described below, and a toner exhibiting excellent low-temperature fixability can be obtained, which is preferable.

Among these, it is preferable that the weight average molecular weight (Mw1) of the resin (b1) is 200,000 to 2,000,000, the weight average molecular weight (Mw2) of the resin (b2) is 100,000 to 500,000, and the weight average molecular weight (Mw1) of the resin (b1) is greater than the weight average molecular weight (Mw2) of the resin (b2).

The number average molecular weight (Mn) and weight average molecular weight (Mw) in the present invention can be measured using gel permeation chromatography (GPC) under the following conditions.
-Measurement conditions-
・Device (example): "HLC-8120" (manufactured by Tosoh Corporation)
Column (example): 2 "TSK GEL GMH6" (manufactured by Tosoh Corporation) Measurement temperature: 40°C
Sample solution: 0.25 wt% tetrahydrofuran solution (insoluble matter was filtered off using a glass filter)
・Solution injection amount: 100μl
Detector: Refractive index detector Reference material: 12 standard polystyrenes (TSKstandard POLYSTYRENE) (molecular weights: 500, 1,050, 2,800, 5,970, 9,100, 18,100, 37,900, 96,400, 190,000, 355,000, 1,090,000, 2,890,000) (manufactured by Tosoh Corporation)

The mass ratio of the resin (b1) to the resin (b2) in the resin fine particles (B) [mass of resin (b1)/mass of resin (b2)] is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 5/95 to 95/5, more preferably 25/75 to 75/25, and even more preferably 40/60 to 60/40.
When the mass ratio of the resin (b1) to the resin (b2) is 5/95 or more, the toner has excellent heat resistance and storage stability, and when the mass ratio of the resin (b1) to the resin (b2) is 95/5 or less, it is easy to form a toner having the resin fine particles (B) on the surface of the toner base particles described later, which is preferable.

The content of the resin particles (B) (the sum of the masses of the resins (b1) and (b2)) is preferably 0.2% by mass or more and 5% by mass or less relative to the toner. When the sum of the masses of the resins (b1) and (b2) is in the above range, low-temperature fixability and heat-resistant storage stability are improved, which is preferable.
When the content of the resin fine particles (B) is 0.2% by mass or more relative to the toner, problems such as deterioration of heat-resistant storage stability can be prevented, and when the content of the resin fine particles (B) is 5% by mass or less relative to the toner, problems such as deterioration of low-temperature fixability can be prevented.

<Volume average primary particle size>
The volume average primary particle diameter of the resin fine particles (B) is preferably 10 nm or more and 100 nm or less, more preferably 10 nm or more and 50 nm or less, from the viewpoint of obtaining a toner that exhibits good low-temperature fixability.
The volume-average primary particle size can be measured, for example, by observing images with a scanning electron microscope (SEM) or by using a dynamic light scattering particle size distribution analyzer (LB).

In the toner of the present invention, the resin fine particles (B) may be used alone, but it is preferable to use a combination of resin fine particles (B) made of two types of styrene-acrylic resins (resin (b1) and resin (b2)) and resin fine particles (A) made of one type of styrene-acrylic resin.
In the toner production process of the present invention, the resin fine particles (A) and the resin fine particles (B) that have been mixed in advance during emulsification are uniformly adhered to the surfaces of the toner base particles, and the resin fine particles (A) that have adhered to the toner surfaces and all or part of the resin (b1) in the resin fine particles (B) are removed in a washing step described later, whereby the resin fine particles (B) can be adhered with uniform gaps.
In the toner of the present invention, the mass ratio of the resin fine particles (B) to the resin fine particles (A) [(B)/(A)] is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1/4, and more preferably 1/2.

The method for producing the resin fine particles (B) is not particularly limited, and known production methods can be used. For example, a method in which a core resin is formed and then a shell resin is formed to cover the core resin, or a method in which a shell resin is formed and then a core resin is formed within the shell resin, can be used.
Although the details of the mechanism of the method of forming the above-mentioned shell resin and then forming a core resin within the shell resin are not clear, it is thought that by adjusting the hydrophobicity, etc. of the constituent monomers of resin (b2) to make them more compatible with resin (b1) than with water, the constituent monomers of resin (b2) can be absorbed into resin (b1), thereby synthesizing resin (b2) within resin (b1).
Specific examples of the method for producing the resin fine particles (B) include the following production methods (I) to (V), and any of the production methods (I) to (V) shown below can be suitably employed.

(I) Method of seed polymerization of constituent monomers of resin (b2) using resin (b1) in an aqueous dispersion as a seed. Specific examples of (I) include a method of dropwise polymerizing constituent monomers of resin (b1) to produce an aqueous dispersion of particles containing resin (b1), and then using this as a seed to seed polymerize constituent monomers of resin (b2); and a method of emulsifying and dispersing resin (b1) previously produced by solution polymerization or the like in water, and then using this as a seed to seed polymerize constituent monomers of resin (b2).

(II) Method of seed polymerization of constituent monomers of resin (b1) using resin (b2) in an aqueous dispersion as a seed Specific examples of (II) include a method of dropwise polymerizing constituent monomers of resin (b2) to produce an aqueous dispersion of particles containing resin (b2), and then using this as a seed to seed polymerize constituent monomers of resin (b1); and a method of emulsifying and dispersing resin (b2) previously produced by solution polymerization or the like in water, and then using this as a seed to seed polymerize constituent monomers of resin (b1).

(III) A method of emulsifying a mixture of resin (b1) and resin (b2) in an aqueous medium to obtain an aqueous dispersion of resin fine particles. A specific example of (III) above is a method of mixing a solution or melt of resin (b1) and resin (b2) that have been previously produced by solution polymerization or the like, and then emulsifying and dispersing the mixture in an aqueous medium.

(IV) A method of emulsifying a mixture of resin (b1) and the constituent monomers of resin (b2) in an aqueous medium, and then polymerizing the constituent monomers of resin (b2) to obtain an aqueous dispersion of resin fine particles. Specific examples of (IV) include a method of mixing resin (b1) previously produced by solution polymerization or the like with the constituent monomers of resin (b2), emulsifying and dispersing the mixture in an aqueous medium, and then polymerizing the constituent monomers of resin (b2); and a method of producing resin (b1) in the constituent monomers of resin (b2), emulsifying and dispersing the mixture in an aqueous medium, and then polymerizing the constituent monomers of resin (b2).

(V) A method of emulsifying a mixture of resin (b2) and the constituent monomers of resin (b1) in an aqueous medium, and then polymerizing the constituent monomers of resin (b1) to obtain an aqueous dispersion of resin fine particles. Specific examples of (V) include a method of mixing resin (b2) previously produced by solution polymerization or the like with the constituent monomers of resin (b1), emulsifying and dispersing the mixture in an aqueous medium, and then polymerizing the constituent monomers of resin (b1); and a method of producing resin (b2) from the constituent monomers of resin (b1), emulsifying and dispersing the mixture in an aqueous medium, and then polymerizing the constituent monomers of resin (b1).

The fact that the resin microparticles (B) contain the resin (b1) and the resin (b2) as constituent components within the same particle can be confirmed by observing an element mapping image of a cut surface of the resin microparticles (B) using a known surface elemental analyzer (such as TOF-SIM-SEDX-SEM), and by observing an electron microscope image of a cut surface of the resin microparticles (B) stained with a staining agent corresponding to the functional groups contained in the resin (b1) and the resin (b2).
Furthermore, the resin microparticles obtained by this method may be obtained as a mixture containing, in addition to the resin microparticles (B) containing the resin (b1) and the resin (b2) as constituent components within the same particle, resin microparticles having only the resin (b1) as a constituent resin component, and resin microparticles having only the resin (b2) as a constituent resin component. In the composite particle formation step described below, the mixture may be used as is, or only the resin microparticles (B) may be isolated and used.

The resin fine particles (B) are preferably used in the form of an aqueous dispersion.
The substance (aqueous medium) used in the aqueous dispersion is not particularly limited as long as it is soluble in water and can be appropriately selected depending on the purpose, and examples thereof include a surfactant (D), a buffering agent, a protective colloid, etc. These may be used alone or in combination of two or more.
The aqueous medium used in the aqueous dispersion is not particularly limited as long as it is a liquid that essentially contains water, and examples thereof include aqueous solutions containing water.

-Surfactant (D)-
The surfactant (D) is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include nonionic surfactants (D1), anionic surfactants (D2), cationic surfactants (D3), amphoteric surfactants (D4), and other emulsifying dispersants (D5).

The nonionic surfactant (D1) is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include AO (alkylene oxide) addition type nonionic surfactants and polyhydric alcohol type nonionic surfactants.
Examples of the AO-addition type nonionic surfactant include EO adducts of aliphatic alcohols having 10 to 20 carbon atoms, EO adducts of phenols, EO (ethylene oxide) adducts of nonylphenols, EO adducts of alkylamines having 8 to 22 carbon atoms, and EO adducts of poly(oxypropylene) glycols.
Examples of the polyhydric alcohol-type nonionic surfactant include fatty acid (8 to 24 carbon atoms) esters of polyhydric (trihydric to octahydric or higher) alcohols (2 to 30 carbon atoms) (e.g., glycerin monostearate, glycerin monooleate, sorbitan monolaurate, sorbitan monooleate, etc.), alkyl (4 to 24 carbon atoms) poly(degree of polymerization 1 to 10) glycosides, and the like.

The anionic surfactant (D2) is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include ethercarboxylic acids having a hydrocarbon group of 8 to 24 carbon atoms or salts thereof, sulfates or ether sulfates having a hydrocarbon group of 8 to 24 carbon atoms and salts thereof, sulfonates having a hydrocarbon group of 8 to 24 carbon atoms, sulfosuccinates having one or two hydrocarbon groups of 8 to 24 carbon atoms, phosphates or ether phosphates having a hydrocarbon group of 8 to 24 carbon atoms and salts thereof, fatty acid salts having a hydrocarbon group of 8 to 24 carbon atoms, and acylated amino acid salts having a hydrocarbon group of 8 to 24 carbon atoms.
Examples of the ethercarboxylic acid or salt thereof having a hydrocarbon group having 8 to 24 carbon atoms include sodium lauryl ether acetate and (poly)oxyethylene (addition mole number 1 to 100) sodium lauryl ether acetate.
Examples of the sulfate ester or ether sulfate ester having a hydrocarbon group having 8 to 24 carbon atoms and salts thereof include sodium lauryl sulfate, (poly)oxyethylene (number of moles added: 1 to 100) sodium lauryl sulfate, (poly)oxyethylene (number of moles added: 1 to 100) triethanolamine lauryl sulfate, and (poly)oxyethylene (number of moles added: 1 to 100) coconut oil fatty acid monoethanolamide sodium sulfate.
Examples of the sulfonate salts having a hydrocarbon group having 8 to 24 carbon atoms include sodium dodecylbenzenesulfonate.
Examples of the phosphate ester or ether phosphate ester having a hydrocarbon group having 8 to 24 carbon atoms and salts thereof include sodium lauryl phosphate and sodium (poly)oxyethylene (number of moles added: 1 to 100) lauryl ether phosphate.
Examples of the fatty acid salts having a hydrocarbon group having 8 to 24 carbon atoms include sodium laurate and triethanolamine laurate.
Examples of the acylated amino acid salts having a hydrocarbon group having 8 to 24 carbon atoms include sodium coconut oil fatty acid methyl taurate, sodium coconut oil fatty acid sarcosine, coconut oil fatty acid sarcosine triethanolamine, N-coconut oil fatty acid acyl-L-glutamate triethanolamine, sodium N-coconut oil fatty acid acyl-L-glutamate, and sodium lauroylmethyl-β-alanine.

The cationic surfactant (D3) is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include quaternary ammonium salt types and amine salt types.
Examples of the quaternary ammonium salt type include stearyltrimethylammonium chloride, behenyltrimethylammonium chloride, distearyldimethylammonium chloride, and lanolin fatty acid aminopropylethyldimethylammonium ethyl sulfate.
Examples of the amine salt type include stearic acid diethylaminoethylamide lactate, dilaurylamine hydrochloride, and oleylamine lactate.

The amphoteric surfactant (D4) is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include betaine-type amphoteric surfactants and amino acid-type amphoteric surfactants.
Examples of the betaine type amphoteric surfactant include coconut oil fatty acid amidopropyl dimethylaminoacetic acid betaine, lauryl dimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine, and lauryl hydroxysulfobetaine.
Examples of the amino acid type amphoteric surfactant include sodium β-laurylaminopropionate.

The other emulsifying dispersant (D5) is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include reactive activators.
The reactive activator is not particularly limited as long as it has radical reactivity and can be appropriately selected depending on the purpose. Examples thereof include ADEKA REASOAP (registered trademark) SE-10N, SR-10, SR-20, SR-30, ER-20, and ER-30 (all manufactured by ADEKA Corporation), AQUALON (registered trademark) HS-10, KH-05, KH-10, and KH-1025 (all manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), ELEMINOL (registered trademark) JS-20 (manufactured by Sanyo Chemical Industries, Ltd.), and LATEMUL (registered trademark) D-104, PD-420, and PD-430 (all manufactured by Kao Co., Ltd.), IONET (registered trademark) MO-200 (Sanyo Chemical Industries, Ltd.), polyvinyl alcohol, starch or a derivative thereof, cellulose derivatives such as carboxymethyl cellulose, methyl cellulose, and hydroxyethyl cellulose, carboxyl group-containing (co)polymers such as polysodium acrylate, and emulsifying dispersants having a urethane group or an ester group described in U.S. Pat. No. 5,906,704 (for example, a compound obtained by linking a polycaprolactone polyol and a polyether diol with a polyisocyanate).

As the surfactant (D), from the viewpoint of stabilizing oil droplets during emulsification and dispersion, obtaining the desired shape, and sharpening the particle size distribution, a combination of a nonionic surfactant (D1), an anionic surfactant (D2), and another emulsifying dispersant (D5) is preferred, and a combination of a nonionic surfactant (D1) and another emulsifying dispersant (D5), and a combination of an anionic surfactant (D2) and another emulsifying dispersant (D5) are more preferred.

-Buffer-
The buffering agent is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include sodium acetate, sodium citrate, and sodium bicarbonate.

-Protective colloid-
The protective colloid is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include water-soluble cellulose compounds and alkali metal salts of polymethacrylic acid.

In addition to the resin (b1) and the resin (b2), the resin microparticles (B) may contain other resin components, an initiator (and its residue), a chain transfer agent, an antioxidant, a plasticizer, a preservative, a reducing agent, an organic solvent, etc.

-Other resin components-
The other resin component is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include vinyl resins other than the resins used in the resin (b1) and the resin (b2), polyurethane resins, epoxy resins, polyester resins, polyamide resins, polyimide resins, silicon resins, phenolic resins, melamine resins, urea resins, aniline resins, ionomer resins, and polycarbonate resins.

- Initiator (and its residue) -
The initiator (and its residue) is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include known radical polymerization initiators.
Specific examples of the initiator (and its residue) include persulfate initiators such as potassium persulfate and ammonium persulfate; azo initiators such as azobisisobutyronitrile; organic peroxides such as benzoyl peroxide, cumene hydroperoxide, tertiary butyl hydroperoxide, tertiary butyl peroxyisopropyl monocarbonate, and tertiary butyl peroxybenzoate; and hydrogen peroxide.

- Chain transfer agent -
The chain transfer agent is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include n-dodecyl mercaptan, tert-dodecyl mercaptan, n-butyl mercaptan, 2-ethylhexyl thioglycolate, 2-mercaptoethanol, β-mercaptopropionic acid, and α-methylstyrene dimer.

-Antioxidant-
The antioxidant is not particularly limited and can be appropriately selected depending on the purpose. Examples of the antioxidant include phenol compounds, paraphenylenediamine, hydroquinone, organic sulfur compounds, and organic phosphorus compounds.

Examples of the phenolic compounds include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2,2'-methylene-bis-(4-methyl-6-t-butylphenol), 2,2'-methylene-bis-(4-ethyl-6-t-butylphenol), 4,4'-thiobis-(3-methyl-6-t-butylphenol), 4,4'-butylidenebis-(3- methyl-6-t-butylphenol), 1,1,3-tris-(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, bis[3,3'-bis(4'-hydroxy-3'-t-butylphenyl)butyric acid]glycol ester, tocopherol, etc.

Examples of the paraphenylenediamine include N-phenyl-N'-isopropyl-p-phenylenediamine, N,N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N,N'-di-isopropyl-p-phenylenediamine, and N,N'-dimethyl-N,N'-di-t-butyl-p-phenylenediamine.

Examples of hydroquinones include 2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, and 2-(2-octadecenyl)-5-methylhydroquinone.

Examples of the organic sulfur compounds include dilauryl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, and ditetradecyl-3,3'-thiodipropionate.

Examples of the organic phosphorus compound include triphenylphosphine, tri(nonylphenyl)phosphine, tri(dinonylphenyl)phosphine, tricresylphosphine, and tri(2,4-dibutylphenoxy)phosphine.

-Plasticizer-
The plasticizer is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include phthalate esters, aliphatic dibasic acid esters, trimellitate esters, phosphate esters, and fatty acid esters.

Examples of the phthalate esters include dibutyl phthalate, dioctyl phthalate, butyl benzyl phthalate, and diisodecyl phthalate.

Examples of the aliphatic dibasic acid ester include di-2-ethylhexyl adipate and 2-ethylhexyl sebacate.

Examples of the trimellitic acid ester include tri-2-ethylhexyl trimellitate and trioctyl trimellitate.

Examples of the phosphate ester include triethyl phosphate, tri-2-ethylhexyl phosphate, and tricresyl phosphate.

Examples of the fatty acid ester include butyl oleate.

-Preservatives-
The preservative is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include organic nitrogen sulfur compound preservatives and organic sulfur halide preservatives.

-Reducing agent-
The reducing agent is not particularly limited and can be appropriately selected depending on the purpose. Examples of the reducing agent include reducing organic compounds such as ascorbic acid, tartaric acid, citric acid, glucose, and formaldehyde sulfoxylate metal salts; and reducing inorganic compounds such as sodium thiosulfate, sodium sulfite, sodium bisulfite, and sodium metabisulfite.

-Organic solvents-
The organic solvent is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include ketone solvents such as acetone and methyl ethyl ketone (hereinafter abbreviated as MEK); ester solvents such as ethyl acetate and γ-butyrolactone; ether solvents such as THF (tetrahydrofuran); amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone and N-methylcaprolactam; alcohol solvents such as isopropyl alcohol; and aromatic hydrocarbon solvents such as toluene and xylene.

<Toner base particles>
The toner base particles (hereinafter also referred to as "toner base" or "base particles") contain a binder resin, a colorant, and a wax, and may further contain other components (B) as required.

<<Binder resin>>
The binder resin is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include polyester resin, styrene-acrylic resin, polyol resin, vinyl resin, polyurethane resin, epoxy resin, polyamide resin, polyimide resin, silicon resin, phenol resin, melamine resin, urea resin, aniline resin, ionomer resin, polycarbonate resin, etc. Among these, polyester resin is preferred because it can impart flexibility to the toner.
These may be used alone or in combination of two or more.

<<<Polyester resin>>>
The polyester resin is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include crystalline polyester resins, amorphous polyester resins, and modified polyester resins.
These may be used alone or in combination of two or more.

-Crystalline polyester-
The crystalline polyester resin (hereinafter also referred to as "crystalline polyester" or "polyester resin component D") is not particularly limited and can be appropriately selected depending on the purpose. For example, a crystalline polyester resin obtained by reacting a polyol with a polycarboxylic acid can be used.

The crystalline polyester resin has high crystallinity and therefore exhibits a heat melting property in which the viscosity drops sharply near the fixing start temperature.
By using the crystalline polyester resin having such properties in combination with the amorphous polyester resin described below, the toner has good heat-resistant storage stability due to its crystallinity up to just before the melting initiation temperature, and at the melting initiation temperature, the crystalline polyester resin melts, causing a sudden decrease in viscosity (sharp melt), which causes it to become compatible with the amorphous polyester resin, and both resins are fixed due to a sudden decrease in viscosity, thereby obtaining a toner having both good heat-resistant storage stability and low-temperature fixability. Furthermore, the toner also shows good results in terms of release width (the difference between the minimum fixing temperature and the temperature at which high-temperature offset resistance occurs).
In the present invention, the crystalline polyester resin refers to a resin obtained by reacting a polyol with a polycarboxylic acid, as described above, and modified polyester resins, such as the prepolymers and resins obtained by subjecting the prepolymers to a crosslinking and/or elongation reaction, do not fall under the category of crystalline polyester resins.

--Polyol--
The polyol used in the synthesis of the crystalline polyester resin is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include diols and trihydric or higher alcohols.

Examples of the diol used in the synthesis of the crystalline polyester resin include saturated aliphatic diols.
Examples of the saturated aliphatic diol include linear saturated aliphatic diols, branched saturated aliphatic diols, etc. Among these, linear saturated aliphatic diols are preferred, and linear saturated aliphatic diols having 2 to 12 carbon atoms are more preferred, in terms of improving crystallinity and preventing a decrease in melting point.
These may be used alone or in combination of two or more.

Specific examples of the saturated aliphatic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,14-eicosanediol. Among these, ethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, and 1,12-dodecanediol are preferred because they provide the crystalline polyester resin with high crystallinity and excellent sharp melt properties.

Examples of the trivalent or higher alcohols used in the synthesis of the crystalline polyester resin include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

--Polycarboxylic acid--
The polycarboxylic acid used in the synthesis of the crystalline polyester resin is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include divalent carboxylic acids and trivalent or higher carboxylic acids.

Examples of the dicarboxylic acid used in the synthesis of the crystalline polyester resin include saturated aliphatic dicarboxylic acids such as oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid; and aromatic dicarboxylic acids such as dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, malonic acid, and mesaconic acid. Further examples include anhydrides and lower (1 to 3 carbon atoms) alkyl esters of these.

Examples of the trivalent or higher carboxylic acid used in the synthesis of the crystalline polyester resin include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, their anhydrides, and their lower (1 to 3 carbon atoms) alkyl esters.

The polycarboxylic acid used in the synthesis of the crystalline polyester resin may include, in addition to the saturated aliphatic dicarboxylic acid and aromatic dicarboxylic acid, a dicarboxylic acid having a sulfonic acid group, a dicarboxylic acid having a double bond, and the like.
These may be used alone or in combination of two or more.

The crystalline polyester resin is preferably composed of a linear saturated aliphatic dicarboxylic acid having from 4 to 12 carbon atoms and a linear saturated aliphatic diol having from 2 to 12 carbon atoms. That is, the crystalline polyester resin preferably has structural units derived from a saturated aliphatic dicarboxylic acid having from 4 to 12 carbon atoms and structural units derived from a saturated aliphatic diol having from 2 to 12 carbon atoms. This is preferable in that it has high crystallinity and excellent sharp melt properties, allowing it to exhibit excellent low-temperature fixability.

The presence or absence of crystallinity of the crystalline polyester resin in the toner of the present invention can be confirmed by a crystal analysis X-ray diffraction device (for example, X'Pert Pro MRD, manufactured by Philips). The measurement method will be described below.
First, the target sample is ground in a mortar to produce a sample powder, which is then evenly applied to a sample holder.The sample holder is then placed in the diffraction device, and measurements are performed to obtain a diffraction spectrum.
In the obtained diffraction spectrum, when the peak half width of the peak with the greatest peak intensity among the peaks obtained in the range of 20°<2θ<25° was 2.0 or less, it was determined that the resin contained a crystalline polyester resin.
In contrast to crystalline polyester resins, polyester resins that do not exhibit the above-mentioned state are defined as amorphous polyester resins in the present invention.
The conditions for measuring the X-ray diffraction are described below.
-Measurement conditions-
・Tension kV: 45kV
・Current: 40mA
・MPSS
Upper
・Gonio
・Scanmode: continue
・Start angle: 3°
・End angle: 35°
・Angle Step: 0.02°
・Lucident beam optics
・Divergence slit: Div slit 1/2
・Diffrection beam optics
・Anti scatter slit: As Fixed 1/2
・Receiving slit: Prog rec slit

The melting point of the crystalline polyester resin is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 60°C or higher and 80°C or lower.
When the melting point of the crystalline polyester resin is 60°C or higher, the crystalline polyester resin is easily melted at low temperatures, preventing the problem of a decrease in the heat-resistant storage stability of the toner. When the melting point is 80°C or lower, the crystalline polyester resin is not sufficiently melted by heating during fixing, preventing the problem of a decrease in low-temperature fixability.

The molecular weight of the crystalline polyester resin is not particularly limited and can be appropriately selected depending on the purpose.
The weight average molecular weight (Mw) of the orthodichlorobenzene soluble portion of the crystalline polyester resin is preferably 3,000 to 30,000, more preferably 5,000 to 15,000, as measured by GPC.
The number average molecular weight (Mn) of the orthodichlorobenzene soluble portion of the crystalline polyester resin is preferably 1,000 to 10,000, more preferably 2,000 to 10,000, as measured by GPC.
The molecular weight ratio (Mw/Mn) of the crystalline polyester resin is preferably 1.0 to 10, and more preferably 1.0 to 5.0, because a resin having a sharp molecular weight distribution and a low molecular weight has excellent low-temperature fixability, and the heat-resistant storage stability decreases when there are a lot of low-molecular-weight components.

There are no particular restrictions on the acid value of the crystalline polyester resin and it can be selected appropriately depending on the purpose. However, from the viewpoint of affinity between paper and resin, in order to achieve the desired low-temperature fixability, an acid value of 5 mgKOH/g or more is preferred, and 10 mgKOH/g or more is more preferred. On the other hand, in order to improve high-temperature offset resistance, an acid value of 45 mgKOH/g or less is preferred.

There are no particular restrictions on the hydroxyl value of the crystalline polyester resin and it can be selected appropriately depending on the purpose. However, in order to achieve the desired low-temperature fixability and good charging characteristics, it is preferably 0 mgKOH/g to 50 mgKOH/g, and more preferably 5 mgKOH/g to 50 mgKOH/g.

The molecular structure of the crystalline polyester resin can be confirmed by NMR measurement of the solution or solid, as well as X-ray diffraction, GC/MS, LC/MS, IR measurement, etc. A simple method is to detect crystalline polyester resins by detecting absorption at 965±10 cm-1 or 990±10 cm-1 in the infrared absorption spectrum due to the δCH (out-of-plane bending vibration) of olefins.

The content of the crystalline polyester resin is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 3 parts by mass or more and 20 parts by mass or less, and more preferably 5 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of the toner.
When the content of the crystalline polyester resin is 3 parts by mass or more, the problem of poor low-temperature fixability due to insufficient sharp melting by the crystalline polyester resin can be prevented, whereas when the content of the crystalline polyester resin is 20 parts by mass or less, the problem of poor heat-resistant storage stability and image fogging can be prevented.

- Amorphous polyester resin -
The amorphous polyester resin (hereinafter, sometimes referred to as "amorphous polyester,""amorphouspolyester,""amorphous polyester resin,""unmodified polyester resin," or "polyester resin component A") is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include an amorphous polyester resin obtained by reacting a polyol with a polycarboxylic acid.
In the present invention, the amorphous polyester resin refers to a resin obtained by reacting a polyol with a polycarboxylic acid, as described above. That is, modified polyester resins, such as prepolymers described below, and modified polyester resins obtained by subjecting the prepolymers to a crosslinking and/or elongation reaction, are not included in the amorphous polyester resins in the present invention, but are treated as modified polyester resins.
The amorphous polyester resin is a polyester resin component that is soluble in tetrahydrofuran (THF).
The amorphous polyester resin is preferably a linear polyester resin.

--Polyol--
Examples of the polyol used in the synthesis of the amorphous polyester resin include diols.

Examples of diols used in the synthesis of the amorphous polyester resin include alkylene (carbon number 2 to 3) oxide (average number of added moles 1 to 10) adducts of bisphenol A such as polyoxypropylene(2.2)-2,2-bis(4-hydroxyphenyl)propane and polyoxyethylene(2.2)-2,2-bis(4-hydroxyphenyl)propane; ethylene glycol; propylene glycol; hydrogenated bisphenol A; and alkylene (carbon number 2 to 3) oxide (average number of added moles 1 to 10) adducts of hydrogenated bisphenol A. Among these, it is preferable that the polyol contains 40 mol% or more of alkylene glycol.
These may be used alone or in combination of two or more.

--Polycarboxylic acid--
Examples of the polycarboxylic acid used in the synthesis of the amorphous polyester resin include dicarboxylic acids.

Examples of the dicarboxylic acid used in the synthesis of the amorphous polyester resin include adipic acid, phthalic acid, isophthalic acid, terephthalic acid, fumaric acid, maleic acid, dodecenylsuccinic acid, octylsuccinic acid, and other alkyl groups having 1 to 20 carbon atoms; succinic acid substituted with an alkenyl group having 2 to 20 carbon atoms. Among these, the polycarboxylic acid preferably contains 50 mol % or more of terephthalic acid.
These may be used alone or in combination of two or more.

The amorphous polyester resin may contain a trivalent or higher carboxylic acid and/or a trivalent or higher alcohol, a trivalent or higher epoxy compound, etc. at the end of the resin chain in order to adjust the acid value and hydroxyl value. Among these, it is preferable to contain a trivalent or higher aliphatic alcohol from the viewpoint of reducing the occurrence of unevenness and achieving sufficient gloss and image density.
Examples of the trivalent or higher carboxylic acid in the amorphous polyester resin include trimellitic acid, pyromellitic acid, and acid anhydrides thereof.
Examples of the trivalent or higher alcohol in the amorphous polyester resin include glycerin, pentaerythritol, and trimethylolpropane.

The molecular weight of the amorphous polyester resin is not particularly limited and can be appropriately selected depending on the purpose, but is preferably in the following range.
The weight average molecular weight (Mw) of the amorphous polyester resin is preferably 3,000 to 10,000, and more preferably 4,000 to 7,000.
The number average molecular weight (Mn) of the amorphous polyester resin is preferably 1,000 to 4,000, and more preferably 1,500 to 3,000.
The molecular weight ratio (Mw/Mn) of the amorphous polyester resin is preferably 1.0 to 4.0, more preferably 1.0 to 3.5.
The reason why the weight average molecular weight (Mw) and the number average molecular weight (Mn) are preferably within the above ranges is that if the weight average molecular weight (Mw) is less than 3,000 and the number average molecular weight (Mn) is less than 1,000, the toner may be inferior in heat-resistant storage stability and durability to stress such as stirring in a developing machine, whereas if the weight average molecular weight (Mw) exceeds 10,000 and the number average molecular weight (Mn) exceeds 4,000, the viscoelasticity of the toner when melted may increase, resulting in inferior low-temperature fixability.
The weight average molecular weight (Mw) and the number average molecular weight (Mn) can be measured by, for example, GPC (gel permeation chromatography).

The content of components having a molecular weight of 600 or less in the amorphous polyester resin (THF soluble component) is preferably 2% by mass to 10% by mass.
When the content of components having a molecular weight of 600 or less in the amorphous polyester resin (THF soluble component) is 10% by mass or less, problems such as poor heat-resistant storage stability of the toner and poor durability against stress such as stirring in a developing machine can be resolved. When the content of components having a molecular weight of 600 or less in the amorphous polyester resin (THF soluble component) is 2% by mass or more, problems such as poor low-temperature fixability can be resolved.
Examples of a method for adjusting the content of components having a molecular weight of 600 or less in the amorphous polyester resin (THF-soluble component) include a method of extracting the amorphous polyester resin with methanol, removing components having a molecular weight of 600 or less, and purifying the resin.

The acid value of the amorphous polyester resin is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1 mgKOH/g to 50 mgKOH/g, and more preferably 5 mgKOH/g to 30 mgKOH/g.
When the acid value of the amorphous polyester resin is 1 mgKOH/g or more, the toner tends to be negatively charged, and furthermore, the affinity between the toner and paper is improved when fixing to paper, thereby improving low-temperature fixability.When the acid value of the amorphous polyester resin is 50 mgKOH/g or less, the problem of a decrease in charging stability, particularly charging stability against environmental fluctuations, can be prevented.

The hydroxyl value of the amorphous polyester resin is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 5 mgKOH/g or more.

The glass transition temperature (Tg) of the amorphous polyester resin is preferably 40°C to 65°C, more preferably 45°C to 65°C, and even more preferably 50°C to 60°C.
The amorphous polyester resin having a Tg of 40° C. or higher is preferable because it improves the heat-resistant storage stability of the toner, durability against stress such as stirring in a developing machine, and filming resistance.The amorphous polyester resin having a Tg of 65° C. or lower is preferable because it improves deformation due to heat and pressure during toner fixing and improves low-temperature fixability.

The content of the amorphous polyester resin is preferably 80 parts by weight or more and 90 parts by weight or less per 100 parts by weight of toner, as this allows for the production of a toner that combines low-temperature fixability and heat-resistant storage stability.

- Modified polyester resin -
The modified polyester resin (hereinafter, sometimes referred to as "modified polyester" or "polyester resin component C") is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include a reaction product of an active hydrogen group-containing compound and a polyester resin (hereinafter, sometimes referred to as "prepolymer" or "polyester prepolymer") having a site capable of reacting with the active hydrogen group-containing compound.
The modified polyester resin is a polyester resin insoluble in tetrahydrofuran (THF). The tetrahydrofuran (THF)-insoluble polyester resin component reduces Tg and melt viscosity, ensuring low-temperature fixability, and has a branched structure in the molecular skeleton, forming a three-dimensional network structure in the molecular chain, thereby imparting rubber-like properties of being deformed but not flowing at low temperatures.
The modified polyester resin has an active hydrogen group-containing compound and a site capable of reacting with the active hydrogen group-containing compound, and these sites behave like pseudo-crosslinking points, enhancing the rubber-like properties of the amorphous polyester resin, thereby enabling the production of a toner with excellent heat-resistant storage stability and high-temperature offset resistance.

--Compound containing active hydrogen group--
The active hydrogen group-containing compound is a compound that reacts with a polyester resin having a site capable of reacting with the active hydrogen group-containing compound.

The active hydrogen group is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include a hydroxyl group (alcoholic hydroxyl group and phenolic hydroxyl group), an amino group, a carboxyl group, and a mercapto group.
These may be used alone or in combination of two or more.

The active hydrogen group-containing compound is not particularly limited and can be appropriately selected depending on the purpose. However, when the polyester resin having a site capable of reacting with the active hydrogen group-containing compound is a polyester resin containing an isocyanate group, amines are preferred.
When the active hydrogen group-containing compound is an amine, the polyester resin can be made to have a high molecular weight by an elongation reaction, a crosslinking reaction, or the like with the polyester resin.

The amines are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include diamines, trivalent or higher amines, amino alcohols, amino mercaptans, amino acids, and compounds in which the amino groups of these are blocked. Among these, diamines and mixtures of diamines with a small amount of trivalent or higher amines are preferred.
These may be used alone or in combination of two or more.

The diamine is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include aromatic diamines, alicyclic diamines, and aliphatic diamines.
The aromatic diamine is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include phenylenediamine, diethyltoluenediamine, and 4,4'-diaminodiphenylmethane.
The alicyclic diamine is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include 4,4'-diamino-3,3'-dimethyldicyclohexylmethane, diaminocyclohexane, and isophoronediamine.
The aliphatic diamine is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include ethylenediamine, tetramethylenediamine, and hexamethylenediamine.

The trivalent or higher amine is not particularly limited and can be selected appropriately depending on the purpose. Examples include diethylenetriamine and triethylenetetramine.

The amino alcohol is not particularly limited and can be selected appropriately depending on the purpose. Examples include ethanolamine and hydroxyethylaniline.

The amino mercaptan is not particularly limited and can be selected appropriately depending on the purpose. Examples include aminoethyl mercaptan, aminopropyl mercaptan, etc.

The amino acid is not particularly limited and can be selected appropriately depending on the purpose. Examples include aminopropionic acid and aminocaproic acid.

The blocked amino group is not particularly limited and can be selected appropriately depending on the purpose. Examples include ketimine compounds and oxazolizone compounds obtained by blocking the amino group with ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone.

--Polyester resin having a site capable of reacting with an active hydrogen group-containing compound--
The polyester resin having a site capable of reacting with the active hydrogen group-containing compound is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include a polyester resin containing an isocyanate group (hereinafter, sometimes referred to as an "isocyanate group-containing polyester prepolymer").
The polyester resin containing an isocyanate group is not particularly limited and can be appropriately selected depending on the purpose. For example, a reaction product of a polyester resin having an active hydrogen group obtained by polycondensation of a polyol and a polycarboxylic acid with a polyisocyanate can be used.

The polyol used in the synthesis of the polyester resin containing an isocyanate group is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include diols, trihydric or higher alcohols, mixtures of diols and trihydric or higher alcohols, etc. Among these, diols and mixtures of diols and a small amount of trihydric or higher alcohols are preferred.
These may be used alone or in combination of two or more.

The diol used in the synthesis of the polyester resin containing an isocyanate group is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include linear alkylene glycols, diols having an oxyalkylene group, alicyclic diols, bisphenols, alkylene oxide adducts of alicyclic diols, and alkylene oxide adducts of bisphenols.
Examples of the chain alkylene glycol include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, and 1,6-hexanediol.
The number of carbon atoms of the chain alkylene glycol is not particularly limited and can be appropriately selected depending on the purpose, but 2 to 12 is preferred.
Among these, at least one of a chain alkylene glycol having 2 to 12 carbon atoms and an alkylene oxide adduct of a bisphenol is preferred, and an alkylene oxide adduct of a bisphenol and a mixture of an alkylene oxide adduct of a bisphenol and a chain alkylene glycol having 2 to 12 carbon atoms are more preferred.
Examples of the diol having an oxyalkylene group include diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.
Examples of the alicyclic diol include 1,4-cyclohexanedimethanol and hydrogenated bisphenol A.
Examples of the bisphenols include bisphenol A, bisphenol F, and bisphenol S.
Examples of the alkylene oxide include ethylene oxide, propylene oxide, and butylene oxide.

The tri- or higher hydric alcohol used in the synthesis of the polyester resin containing an isocyanate group is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include tri- or higher hydric aliphatic alcohols, tri- or higher hydric polyphenols, and alkylene oxide adducts of tri- or higher hydric polyphenols.
The trivalent or higher aliphatic alcohol is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and sorbitol.
The trivalent or higher polyphenols are not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include trisphenol PA, phenol novolak, and cresol novolak.
Examples of the alkylene oxide adducts of trivalent or higher polyphenols include those obtained by adding alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide to trivalent or higher polyphenols.

When the diol and the trihydric or higher alcohol are used as a mixture, the mass ratio of the trihydric or higher alcohol to the diol (trihydric or higher alcohol/diol) is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 0.01% to 10% by mass, and more preferably 0.01% to 1% by mass.

The polycarboxylic acid used in the synthesis of the polyester resin containing an isocyanate group is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include dicarboxylic acids, tri- or higher carboxylic acids, mixtures of dicarboxylic acids and tri- or higher carboxylic acids, etc. Among these, dicarboxylic acids and mixtures of dicarboxylic acids and a small amount of tri- or higher polycarboxylic acids are preferred.
These may be used alone or in combination of two or more.

The dicarboxylic acid used in the synthesis of the polyester resin containing an isocyanate group is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include divalent alkanoic acids, divalent alkenoic acids, and aromatic dicarboxylic acids.
The divalent alkanoic acid is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include succinic acid, adipic acid, and sebacic acid.
The divalent alkenoic acid is not particularly limited and can be appropriately selected depending on the purpose, but is preferably a divalent alkenoic acid having 4 to 20 carbon atoms.
The divalent alkenoic acid having 4 to 20 carbon atoms is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include maleic acid and fumaric acid.
The aromatic dicarboxylic acid is not particularly limited and can be appropriately selected depending on the purpose, but aromatic dicarboxylic acids having 8 to 20 carbon atoms are preferred.
The aromatic dicarboxylic acid having 8 to 20 carbon atoms is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include phthalic acid, isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid.

The tri- or higher carboxylic acid used in the synthesis of the polyester resin containing an isocyanate group is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include tri- or higher carboxylic acids.
The trivalent or higher aromatic carboxylic acid is not particularly limited and can be appropriately selected depending on the purpose, but is preferably a trivalent or higher aromatic carboxylic acid having 9 to 20 carbon atoms.
The aromatic carboxylic acid having 9 to 20 carbon atoms and a valence of 3 or more is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include trimellitic acid and pyromellitic acid.

The polycarboxylic acid used in the synthesis of the polyester resin containing an isocyanate group may be an acid anhydride or a lower alkyl ester of a dicarboxylic acid, a tri- or higher carboxylic acid, or a mixture of a dicarboxylic acid and a tri- or higher carboxylic acid.
The lower alkyl ester is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include methyl ester, ethyl ester, and isopropyl ester.

When the dicarboxylic acid and the tri- or higher carboxylic acid are used in combination, the mass ratio of the tri- or higher carboxylic acid to the dicarboxylic acid (tri- or higher carboxylic acid/dicarboxylic acid) is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 0.01% to 10% by mass, and more preferably 0.01% to 1% by mass.

When polyol and polycarboxylic acid are polycondensed, the equivalent ratio of hydroxyl groups of the polyol to carboxyl groups of the polycarboxylic acid (hydroxyl groups of polyol/carboxyl groups of polycarboxylic acid) is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 1 to 2, more preferably 1 to 1.5, and particularly preferably 1.02 to 1.3.

The content of the polyol-derived structural unit in the polyester prepolymer containing an isocyanate group is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.5% by mass to 40% by mass, more preferably 1% by mass to 30% by mass, and particularly preferably 2% by mass to 20% by mass.
When the content is 0.5% by mass or more, the hot offset resistance is reduced, and it becomes difficult to achieve both heat-resistant storage stability and low-temperature fixability of the toner. This problem can be solved, and when the content is 40% by mass or less, the problem of low-temperature fixability is reduced can be solved.

The polyisocyanate is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, araliphatic diisocyanates, isocyanurates, and those obtained by blocking these with phenol derivatives, oximes, caprolactam, etc.
The aliphatic diisocyanate is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include tetramethylene diisocyanate, hexamethylene diisocyanate, methyl 2,6-diisocyanatocaproate, octamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, tetradecamethylene diisocyanate, trimethylhexane diisocyanate, and tetramethylhexane diisocyanate.
The alicyclic diisocyanate is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include isophorone diisocyanate and cyclohexylmethane diisocyanate.
The aromatic diisocyanate is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include tolylene diisocyanate, diisocyanatodiphenylmethane, 1,5-naphthylene diisocyanate, 4,4'-diisocyanatodiphenyl, 4,4'-diisocyanato-3,3'-dimethyldiphenyl, 4,4'-diisocyanato-3-methyldiphenylmethane, and 4,4'-diisocyanato-diphenyl ether.
The aromatic aliphatic diisocyanate is not particularly limited and can be appropriately selected depending on the purpose. For example, α,α,α',α'-tetramethylxylylene diisocyanate can be used.
The isocyanurates are not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include tris(isocyanatoalkyl)isocyanurate and tris(isocyanatocycloalkyl)isocyanurate.
These may be used alone or in combination of two or more.

When the polyisocyanate is reacted with a polyester resin having a hydroxyl group, the equivalent ratio (NCO/OH) of the isocyanate group of the polyisocyanate to the hydroxyl group of the polyester resin is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1 to 5, more preferably 1.2 to 4, and particularly preferably 1.5 to 2.5.
When the equivalent ratio is 1 or more, the problem of reduced hot offset resistance can be solved, and when the equivalent ratio is 5 or less, the problem of reduced low-temperature fixability can be solved.

The content of the polyisocyanate-derived structural unit in the polyester prepolymer having an isocyanate group is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.5% by mass to 40% by mass, more preferably 1% by mass to 30% by mass, and even more preferably 2% by mass to 20% by mass.
When the content is 0.5% by mass or more, the problem of reduced hot offset resistance can be solved, and when the content is 40% by mass or less, the problem of reduced low-temperature fixability can be solved.

The average number of isocyanate groups contained in the polyester prepolymer having an isocyanate group per molecule is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1 or more, more preferably 1.5 to 3, and even more preferably 1.8 to 2.5.
When the average number of isocyanate groups per molecule of the polyester prepolymer having an isocyanate group is 1 or more, the molecular weight of the modified polyester resin decreases, which can solve the problem of reduced hot offset resistance.

The modified polyester resin can be produced by a one-shot method, etc. As an example, a method for producing a urea-modified polyester resin will be described.
First, a polyol and a polycarboxylic acid are heated to 150°C to 280°C in the presence of a catalyst such as tetrabutoxy titanate or dibutyltin oxide, and the water produced is removed, if necessary, under reduced pressure, to obtain a polyester resin having hydroxyl groups.
Next, the polyester resin having a hydroxyl group is reacted with polyisocyanate at 40° C. to 140° C. to obtain a polyester prepolymer having an isocyanate group.
Furthermore, a polyester prepolymer having an isocyanate group is reacted with an amine at 0° C. to 140° C. to obtain a urea-modified polyester resin.

The number average molecular weight (Mn) of the modified polyester resin is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1,000 to 10,000, more preferably 1,500 to 6,000, as measured by GPC (gel permeation chromatography).
The weight average molecular weight (Mw) of the modified polyester resin is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 20,000 or more and 1,000,000 or less as measured by GPC (gel permeation chromatography).
When the weight average molecular weight (Mw) of the modified polyester resin is 20,000 or more, the toner tends to flow easily at low temperatures, which can prevent problems such as poor heat-resistant storage stability and low viscosity during melting, which can prevent problems such as poor high-temperature offset properties.

When reacting the polyester resin having hydroxyl groups with the polyisocyanate, and when reacting the polyester prepolymer having isocyanate groups with the amines, a solvent can be used as needed.

The solvent is not particularly limited and can be appropriately selected depending on the purpose. Examples of the solvent include aromatic solvents, ketones, esters, amides, ethers, and other solvents that are inactive to isocyanate groups.
Examples of the aromatic solvent include toluene and xylene.
Examples of the ketones include acetone, methyl ethyl ketone, and methyl isobutyl ketone.
Examples of the esters include ethyl acetate.
Examples of the amides include dimethylformamide and dimethylacetamide.
Examples of the ethers include tetrahydrofuran.

The glass transition temperature (Tg) of the modified polyester resin is preferably −60° C. or higher and 0° C. or lower, and more preferably −40° C. or higher and −20° C. or lower.
If the glass transition temperature (Tg) of the modified polyester resin is −60° C. or higher, the flow of the toner at low temperatures cannot be suppressed, which can prevent problems such as deterioration of heat-resistant storage stability and filming resistance.
When the glass transition temperature (Tg) of the modified polyester resin is 0° C. or lower, the toner cannot be sufficiently deformed by the heat and pressure applied during fixing, and the problem of insufficient low-temperature fixing property can be prevented.

The content of the modified polyester resin is not particularly limited and can be selected appropriately depending on the purpose, but it is preferably 1 to 15 parts by weight, and more preferably 5 to 10 parts by weight, per 100 parts by weight of the toner.

The molecular structures of the amorphous polyester resin and the modified polyester resin can be confirmed by NMR measurement using a solution or solid, as well as X-ray diffraction, GC/MS, LC/MS, IR measurement, and the like.
A simple method includes detecting an amorphous polyester resin by detecting an infrared absorption spectrum that does not have absorption due to olefin δCH (out-of-plane bending vibration) at 965±10 cm −1 and 990±10 cm −1 .

<<Coloring Agents>>
The colorant is not particularly limited and can be appropriately selected depending on the purpose. Examples of the colorant include carbon black, nigrosine dyes, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, yellow ochre, chrome yellow, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Balkan fast yellow (5G, R), tartrazine lake, quinoline yellow lake, anthrazan yellow BGL, and isoindolinone yellow. , red iron oxide, red lead, vermilion lead, cadmium red, cadmium mercury red, antimony vermilion, permanent red 4R, para red, faise red, parachlor orthonitroaniline red, Lithol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, permanent red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belcan Fast Rubin B, Brilliant Scarlet G, Lithol Rubin GX, permanent red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B , Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red, Polyazo Red, Chrome Vermilion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkali Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal-free Phthalocyanine Blue, Lid Examples of pigments that may be used include cyanine blue, fast sky blue, indanthrene blue (RS, BC), indigo, ultramarine, Prussian blue, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment green B, naphthol green B, green gold, acid green lake, malachite green lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc white, and lithopone.

The content of the colorant is not particularly limited and can be selected appropriately depending on the purpose, but it is preferably 1 part by weight to 15 parts by weight, and more preferably 3 parts by weight to 10 parts by weight, per 100 parts by weight of the toner.

The colorant can also be used as a masterbatch in which it is combined with a resin.
Examples of resins to be used in the production of the masterbatch or to be kneaded with the masterbatch (masterbatch resins) include polymers of styrene or its substitution products, such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, and styrene-α-chloromethyl methacrylate copolymer. styrene copolymers such as styrene-acrylonitrile copolymers, styrene-vinyl methyl ketone copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-acrylonitrile-indene copolymers, styrene-maleic acid copolymers, and styrene-maleic acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resins, epoxy polyol resins, polyurethanes, polyamides, polyvinyl butyral, polyacrylic acid resins, rosin, modified rosin, terpene resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffin, and paraffin wax.
These may be used alone or in combination of two or more.

The masterbatch can be obtained by mixing and kneading a masterbatch resin and a colorant under high shear force. An organic solvent can be used to enhance the interaction between the colorant and resin. The so-called flushing method, in which an aqueous paste containing the colorant in water is mixed and kneaded with the resin and organic solvent, the colorant is transferred to the resin, and the water and organic solvent components are removed, is also preferred because the colorant wet cake can be used as is, eliminating the need for drying. A high-shear dispersing device such as a three-roll mill is preferably used for mixing and kneading.

<<Wax>>
The wax (releasing agent) is not particularly limited and can be appropriately selected from known waxes, such as natural waxes and synthetic waxes.
These may be used alone or in combination of two or more.

Examples of the natural waxes include plant waxes such as carnauba wax, cotton wax, and rice wax; animal waxes such as beeswax and lanolin; mineral waxes such as ozokerite and cerusine; and petroleum waxes such as paraffin, microcrystalline, and petrolatum.
Examples of the synthetic wax include synthetic hydrocarbon waxes such as Fischer-Tropsch wax, polyethylene, and polypropylene; fatty acid amide compounds such as esters, ketones, ethers, 12-hydroxystearic acid amide, stearic acid amide, phthalimide anhydride, and chlorinated hydrocarbons; homopolymers or copolymers of polyacrylates such as poly-n-stearyl methacrylate and poly-n-lauryl methacrylate, which are low molecular weight crystalline polymer resins (for example, n-stearyl acrylate-ethyl methacrylate copolymers); and crystalline polymers having long alkyl groups on their side chains.
Among these, hydrocarbon waxes such as paraffin wax, microcrystalline wax, Fischer-Tropsch wax, polyethylene wax, and polypropylene wax are preferred.

The melting point of the wax is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 60° C. or higher and 80° C. or lower.
When the melting point of the wax is 60° C. or higher, the release agent is likely to melt at low temperatures, preventing the problem of poor heat-resistant storage stability.When the melting point of the wax is 80° C. or lower, the wax does not melt sufficiently even when the resin melts and is in the fixing temperature range, preventing the problem of fixing offset and image defects.

The content of the wax is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 2 parts by mass or more and 10 parts by mass or less, and more preferably 3 parts by mass or more and 8 parts by mass or less, relative to 100 parts by mass of the toner.
When the content of the wax is 2 parts by mass or more, it is possible to prevent problems such as poor high-temperature offset resistance and poor low-temperature fixability during fixing, and when the content of the wax is 10 parts by mass or less, it is possible to prevent problems such as a decrease in heat-resistant storage stability and a tendency for image fogging to occur.

The other component (B) in the toner base particles is not particularly limited as long as it is one that is used in ordinary toner base particles, and can be appropriately selected depending on the purpose.
The content of the other component (B) is not particularly limited as long as it does not impair the properties of the toner, and can be appropriately selected depending on the purpose.

<Other Components (A)>
The other components (A) in the toner are not particularly limited as long as they are those used in ordinary toners and can be appropriately selected depending on the purpose. Examples thereof include a charge control agent, an external additive, a flowability improver, a cleaning property improver, and a magnetic material.

-Charge control agent-
The charge control agent is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdic acid chelate pigments, rhodamine dyes, alkoxyamines, quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), alkylamides, phosphorus simple substance or compounds, tungsten simple substance or compounds, fluorine-based activators, metal salicylate, and metal salts of salicylic acid derivatives.

Commercially available charge control agents include, for example, the nigrosine dye Bontron 03, the quaternary ammonium salt Bontron P-51, the metal-containing azo dye Bontron S-34, the oxynaphthoic acid metal complex E-82, the salicylic acid metal complex E-84, and the phenol condensate E-89 (all manufactured by Orient Chemical Industry Co., Ltd.), the quaternary ammonium salt molybdenum complexes TP-302 and TP-415 (both manufactured by Hodogaya Chemical Co., Ltd.), LRA-901, and the boron complex LR-147 (all manufactured by Nippon Carlit Co., Ltd.).

The content of the charge control agent is determined depending on the type of binder resin, the presence or absence of additives used as needed, and the toner production method including the dispersion method, and is not uniquely limited, but is preferably 0.1 parts by mass to 10 parts by mass, and more preferably 0.2 parts by mass to 5 parts by mass, relative to 100 parts by mass of the binder resin.
If the content of the charge control agent is 10 parts by mass or less, the toner has too high a chargeability, which reduces the effect of the main charge control agent, increases the electrostatic attraction force with the developing roller, and causes problems such as reduced fluidity of the developer and reduced image density.
The charge control agent may be melt-kneaded together with the master batch and the resin, and then dissolved and dispersed, or may be added when directly dissolved or dispersed in an organic solvent, or may be fixed on the surface of the toner after the toner particles are produced.

-External additives-
The external additive is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include silica fine particles, hydrophobic silica, fatty acid metal salts (e.g., zinc stearate, aluminum stearate, etc.), metal oxides (e.g., titania, alumina, tin oxide, antimony oxide, etc.), fluoropolymers, etc. Among these, inorganic fine particles are preferred, and hydrophobically treated inorganic fine particles are more preferred.
The hydrophobic inorganic fine particles are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include hydrophobic titanium oxide fine particles and hydrophobic silica fine particles.
These may be used alone or in combination of two or more.

Commercially available products of the silica fine particles include, for example, R972, R974, RX200, RY200, R202, R805, and R812 (all manufactured by Nippon Aerosil Co., Ltd.).
Examples of commercially available titania products include P-25 (manufactured by Nippon Aerosil Co., Ltd.), STT-30, STT-65C-S (all manufactured by Titanium Kogyo Co., Ltd.), TAF-140 (manufactured by Fuji Titanium Kogyo Co., Ltd.), MT-150W, MT-500B, MT-600B, and MT-150A (all manufactured by Teika Corporation).
Commercially available hydrophobized titanium oxide fine particles include, for example, T-805 (manufactured by Nippon Aerosil Co., Ltd.), STT-30A, STT-65S-S (both manufactured by Titanium Kogyo Co., Ltd.), TAF-500T, TAF-1500T (both manufactured by Fuji Titanium Kogyo Co., Ltd.), MT-100S, MT-100T (both manufactured by Teika Corporation), and IT-S (manufactured by Ishihara Sangyo Kaisha, Ltd.).

The hydrophobic treatment can be carried out by using hydrophilic fine particles and a silane coupling agent such as methyltrimethoxysilane, methyltriethoxysilane, or octyltrimethoxysilane.
In addition, silicone oil-treated oxide fine particles and silicone oil-treated inorganic fine particles, which are inorganic fine particles or oxide fine particles treated with silicone oil, are also suitable. In the treatment using silicone oil, heat may be applied as necessary.

The silicone oil is not particularly limited and can be selected appropriately depending on the purpose. Examples include dimethyl silicone oil, methylphenyl silicone oil, chlorophenyl silicone oil, methylhydrogen silicone oil, alkyl-modified silicone oil, fluorine-modified silicone oil, polyether-modified silicone oil, alcohol-modified silicone oil, amino-modified silicone oil, epoxy-modified silicone oil, epoxy-polyether-modified silicone oil, phenol-modified silicone oil, carboxyl-modified silicone oil, mercapto-modified silicone oil, methacrylic-modified silicone oil, and α-methylstyrene-modified silicone oil.

The average particle size of the primary particles in the external additive is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 100 nm or less, more preferably 1 nm to 100 nm, even more preferably 3 nm to 70 nm, and particularly preferably 5 nm to 70 nm.
When the average particle size of the primary particles in the external additive is within the above range, it is possible to prevent the inorganic fine particles from being buried in the toner, making it difficult for them to effectively perform their functions, and the photosensitive member surface from being unevenly damaged.
The external additive preferably contains at least one type of inorganic fine particles that have been hydrophobized and have an average primary particle size of 20 nm or less, and at least one type of inorganic fine particles that have an average primary particle size of 30 nm or more.
The specific surface area of the external additive as measured by the BET method is preferably 20 m ² /g to 500 m ² /g.

The content of the external additive is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 0.1 parts by weight or more and 5 parts by weight or less, and more preferably 0.3 parts by weight or more and 3 parts by weight or less, per 100 parts by weight of the toner.

- Flow improver -
The flowability improver is not particularly limited as long as it is capable of performing a surface treatment to increase hydrophobicity and preventing deterioration of flowability and charging properties even under high humidity conditions, and can be appropriately selected depending on the purpose. Examples of the flowability improver include silane coupling agents, silylating agents, silane coupling agents having a fluorinated alkyl group, organic titanate coupling agents, aluminum coupling agents, silicone oils, and modified silicone oils.
It is particularly preferable that the silica and titanium oxide are surface-treated with the flowability improver and used as hydrophobic silica and hydrophobic titanium oxide.

- Cleaning improver -
The cleaning property improver is not particularly limited as long as it is added to the toner in order to remove the developer remaining on the photosensitive member or the primary transfer medium after transfer, and can be appropriately selected depending on the purpose. Examples of the cleaning property improver include fatty acid metal salts such as zinc stearate, calcium stearate, and stearic acid, and polymer fine particles produced by soap-free emulsion polymerization, such as polymethyl methacrylate fine particles and polystyrene fine particles.
The polymer particles preferably have a relatively narrow particle size distribution, and preferably have a volume average particle size of 0.01 μm to 1 μm.

-Magnetic materials-
The magnetic material is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include iron powder, magnetite, ferrite, etc. Among these, white materials are preferred in terms of color tone.

In the toner of the present invention, the glass transition temperature (Tg1st) at the first temperature rise in differential scanning calorimetry (DSC) is preferably 40°C to 65°C.
The glass transition temperature (Tg1st) of the component of the toner that is insoluble in tetrahydrofuran (THF) at the first temperature rise in DSC is preferably from -45°C to 5°C.
The THF-soluble component of the toner preferably has a glass transition temperature (Tg2nd) at the second temperature rise in DSC of 20°C to 65°C.
The glass transition temperature (Tg1st) in the first temperature rise and the glass transition temperature (Tg2nd) in the second temperature rise in differential scanning calorimetry (DSC) of the toner preferably satisfy Tg1st-Tg2nd≧10° C., in order to obtain a toner having improved low-temperature fixability and heat-resistant storage stability.

The glass transition temperature of the toner can be measured using, for example, a differential scanning calorimeter (DSC-60, manufactured by Shimadzu Corporation).
For example, a DSC curve is measured using the differential scanning calorimeter. From the obtained DSC curve, a DSC curve at the first temperature rise is selected using an analysis program, and the glass transition temperature at the first temperature rise (Tg1st) can be determined using the endothermic shoulder temperature in the analysis program. A DSC curve at the second temperature rise is selected, and the glass transition temperature at the second temperature rise (Tg2nd) can be determined using the endothermic shoulder temperature.

<Aggregates of resin fine particles>
In the present invention, the resin fine particles (B) and aggregates formed by agglomeration of the resin fine particles (B) are present on the surface of the toner base particles.
The term "aggregate" in the present invention refers to particles having a major axis of 3R or more, where R is the major axis of the smallest particle of the resin fine particles (B) present on the surface of the toner base particle.
The term "smallest particle" in the present invention refers to a resin particle having the smallest outer periphery among the resin particles (fine resin particles or aggregates) present on the toner base particle.
In the present invention, the major axis of the aggregate is represented by R'.

<Method for measuring major diameter R and R'>
The toner is subjected to a process of releasing external additives using ultrasonic waves to remove as much of the external additives as possible, and after the toner is brought into a state close to that of toner base particles, the major axis R of the smallest particle is determined.
[1] 50 ml of a 5% by mass aqueous solution containing a surfactant (product name: Noigen ET-165, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) is added to a 100 ml screw tube, and 3 g of toner is added to the mixture, followed by gently moving the mixture up and down and left and right. The mixture is then stirred for 30 minutes in a ball mill to allow the toner to blend into the dispersion solution.
[2] Using an ultrasonic homogenizer (trade name: homogenizer, model VCX750, CV33, manufactured by SONICS & MATERIALS LLC), set the output to 40 W and apply ultrasonic energy for 60 minutes.
-Ultrasonic conditions-
・Vibration time: 60 minutes continuous ・Amplitude: 40W
・Vibration start temperature: 23±1.5℃
・Temperature during vibration: 23±1.5℃
[3] (1) The dispersion liquid is suction filtered using filter paper (product name: Qualitative Filter Paper (No. 2, 110 mm), manufactured by Advantec Toyo Co., Ltd.), washed twice with ion-exchanged water, and then filtered again to remove the liberated additives, and the toner is then dried.
(2) Randomly select the toner obtained in (1) and observe it with a scanning electron microscope (SEM). First, the external additives and charge control agents containing Si are detected by observing the backscattered electron image, and the backscattered electron image is taken.
(3) The obtained backscattered electron image is binarized (threshold: 135) using image processing software (ImageJ) to prepare an image from which the external additives and the charge control agent have been removed.
(4) A secondary electron image is observed and photographed at the same position as in (2). Since the resin fine particles (OMS) cannot be observed in the backscattered electron image but can only be observed in the secondary electron image, the image is compared with the image obtained in (3), and particles present in the areas other than the remaining external additives and charge control agent (areas other than those excluded in (3)) are determined to be resin particles (resin fine particles or aggregates).
(5) Using image processing software (ImageJ), the outer circumferences of the resin particles (resin fine particles or aggregates) on the toner base particles are measured, and the resin fine particles with the smallest outer circumference are determined as the smallest particles. Note that the smallest particles are determined not per visual field but per toner particle.
(6) In the smallest particle, the diameter of a perfect circle having the same circumference as the measured outer circumference is taken as the major axis R.
The major axis R' of the aggregate is also measured in the same manner as the major axis R, and the diameter of a perfect circle having the same circumference as the measured major axis R' is defined as the major axis R'.

<Aggregate Occupancy Ratio>
In the present invention, the ratio of the aggregates to the surface of the toner base particles is 15% or more and 60% or less.
In the present invention, the "proportion of the aggregates occupying the surface of the toner base particle" may be referred to as the "occupancy rate."

The occupation ratio is preferably 15% or more and 60% or less, and more preferably 15% or more and 35% or less.
When the occupancy rate is 15% or more and 60% or less, the amount of liberated external additive can be optimized, the occurrence of filming can be suppressed, and low-temperature fixability and excellent cleanability due to low adhesive force can be simultaneously achieved at a high level.
If the occupancy rate is 15% or more, the external additives on the surface of the toner base particles are likely to be liberated, and the problem of filming occurring due to the excessive liberation can be resolved.
If the occupancy is 60% or less, the agglomerates hinder the heat transfer from the fixing roller, and the problem of insufficient low-temperature fixability can be solved.

<Standard deviation of distance between resin particles>
In the present invention, the distance between the resin particles refers to the shortest distance between the surface of a resin particle present on the surface of a toner base particle and the surface of an adjacent resin particle that is not in contact with the resin particle.
In the present invention, the "shortest distance between the surface of a resin particle present on the surface of a toner base particle and the surface of an adjacent resin particle that is not in contact with the resin particle" may be referred to as the "distance between resin particles."
Since the surface of the toner base particle is not flat but slightly rounded (curved), the distance between the resin fine particles is not the measured distance between the resin fine particles on the surface of the toner base particle, but the shortest distance between the resin fine particles on an image of the resin fine particles on the surface of the toner base particle taken with a scanning electron microscope (SEM).

In the toner of the present invention, the standard deviation of the distance between adjacent resin fine particles that are not in contact with each other and are present on the surface of the toner base particle is preferably 500 nm or less, more preferably 300 nm or less, and even more preferably 150 nm or less.
By making the standard deviation of the distance between the resin particles 500 nm or less, the protective effect of the resin particles on the surface of the toner base particles is not locally exhibited, which can solve the problem of reduced reliability.

<Method for measuring occupation ratio and distance between resin particles>
The toner is subjected to a process of releasing the external additives using ultrasonic waves to remove as much of the external additives as possible, and after the toner is brought into a state close to that of the toner base particles, the occupancy rate and the distance between the resin particles are determined.
[1] 50 ml of a 5% by mass aqueous solution containing a surfactant (product name: Noigen ET-165, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) is added to a 100 ml screw tube, and 3 g of toner is added to the mixture, followed by gently moving the mixture up and down and left and right. The mixture is then stirred for 30 minutes in a ball mill to allow the toner to blend into the dispersion solution.
[2] Using an ultrasonic homogenizer (trade name: homogenizer, model VCX750, CV33, manufactured by SONICS & MATERIALS LLC), set the output to 40 W and apply ultrasonic energy for 60 minutes.
-Ultrasonic conditions-
・Vibration time: 60 minutes continuous ・Amplitude: 40W
・Vibration start temperature: 23±1.5℃
・Temperature during vibration: 23±1.5℃
[3] (1) The dispersion liquid is suction filtered using filter paper (product name: Qualitative Filter Paper (No. 2, 110 mm), manufactured by Advantec Toyo Co., Ltd.), washed twice with ion-exchanged water, and then filtered again to remove the liberated additives, and the toner is then dried.
(2) Randomly select the toner obtained in (1) and observe it with a scanning electron microscope (SEM). First, the external additives and charge control agents containing Si are detected by observing the backscattered electron image, and the backscattered electron image is taken.
(3) The obtained backscattered electron image is binarized (threshold: 135) using image processing software (ImageJ) to prepare an image from which the external additives and the charge control agent have been removed.
(4) A secondary electron image is observed and photographed at the same position as in (2). Since the resin fine particles (OMS) cannot be observed in the backscattered electron image but can only be observed in the secondary electron image, the image is compared with the image obtained in (3), and particles present in the areas other than the remaining external additives and charge control agent (areas other than those excluded in (3)) are determined to be resin particles (resin fine particles or aggregates). The locations where the toner particles are photographed are selected at random.
(5) Using image processing software (ImageJ), binarization (threshold: 135) is performed to create 100 binarized images (one toner particle per image). From the obtained binarized images, the total area occupied by each aggregate, the area of the toner base particles, and the distance between the resin fine particles are measured.
(6) The total area occupied by each aggregate and the area of the toner base particles are averaged to calculate the occupancy rate. The standard deviation is calculated for the distance between the resin particles.
The total area occupied by each aggregate and the area of the toner base particle are defined as the areas of a perfect circle having the same circumference as the measured outer periphery.

The occupation ratio is calculated by the following formula.
Occupancy rate (%) = average value of total area occupied by aggregates / average value of area of toner matrix

The standard deviation of the distance between the resin microparticles is calculated using the following formula, where x is the interparticle distance.

The photographing conditions for the scanning electron microscope (SEM) are as follows.
[Shooting conditions]
Scanning electron microscope: SU-8230 (Hitachi High-Technologies Corporation)
・Photographing magnification: 60,000 times ・Photographed image: SE (L): secondary electrons, BSE (backscattered electrons)
Acceleration voltage: 3.0 kV
・Acceleration current: 1.0μA
・Probe current: Normal
Focus mode: UHR
・WD: 8.0 mm

The toner according to the present invention will now be described with reference to the drawings. The present invention is not limited to the embodiments shown below, and other modifications, additions, corrections, deletions, and other changes may be made within the scope of what one skilled in the art could conceive. Any aspect that achieves the effects and advantages of the present invention is within the scope of the present invention.

Figure 1 is a schematic diagram showing an example of the state of a toner surface. Resin fine particles 3 and aggregates 5 made of resin fine particles are present on the surface of a toner base particle 4. The resin fine particles 3 consist of a core resin 2 and a shell resin 1. M indicates the volume-average primary particle diameter of the resin fine particles 3. L indicates the distance between the resin fine particles.

(Developer)
The developer of the present invention contains at least the toner of the present invention and, if necessary, contains other appropriately selected components such as a carrier, etc. The developer may be a one-component developer or a two-component developer, but when used in a high-speed printer or the like that corresponds to the recent improvement in information processing speed, a two-component developer is preferred because of its improved lifespan.

<Career>
The carrier is not particularly limited and can be appropriately selected depending on the purpose, but is preferably one having a core material and a resin layer covering the core material.

<<Core material>>
The material for the core is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include manganese-strontium-based materials with a repulsion of 50 emu/g to 90 emu/g and manganese-magnesium-based materials with a repulsion of 50 emu/g to 90 emu/g. Furthermore, in order to ensure image density, it is preferable to use high-magnetization materials such as iron powder with a repulsion of 100 emu/g or more, or magnetite with a repulsion of 75 emu/g to 120 emu/g. Furthermore, it is preferable to use low-magnetization materials such as copper-zinc-based materials with a repulsion of 30 emu/g to 80 emu/g, as these materials can mitigate the impact of the developer in a standing state on the photoreceptor and are advantageous for achieving high image quality.
These may be used alone or in combination of two or more.

The volume average particle size of the core material is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10 μm to 150 μm, more preferably 40 μm to 100 μm.
If the volume average particle diameter of the core material is 10 μm or more, the amount of fine powder in the carrier increases, which can solve the problem of carrier scattering due to reduced magnetization per particle.
If the volume average particle diameter of the core material is 150 μm or less, the specific surface area decreases, causing toner scattering, which can solve the problem of poor reproduction of solid areas, especially in full color printing which has many solid areas.

The toner of the present invention can be mixed with the carrier and used in a two-component developer.
The content of the carrier in the two-component developer is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 90 parts by mass or more and 98 parts by mass or less, and more preferably 93 parts by mass or more and 97 parts by mass or less, relative to 100 parts by mass of the two-component developer.
The developer of the present invention can be suitably used for image formation by various known electrophotographic methods such as a magnetic one-component development method, a non-magnetic one-component development method, and a two-component development method.

(Toner manufacturing method)
The toner production method of the present invention is a method for producing the above-mentioned toner.
The method for producing the toner includes a composite particle forming step and a removing step, and may further include other steps as necessary.

<Composite particle formation process>
The composite particle forming step is a step of forming composite particles by adhering the resin fine particles to the surfaces of the toner base particles.
The method for forming the composite particles is not particularly limited and can be appropriately selected depending on the purpose. For example, a known dissolution suspension method can be used in which an oil phase containing components of toner base particles such as a binder resin, a colorant, and a wax is dispersed in an aqueous medium containing resin fine particles to form granules.

As an example of the dissolution suspension method, a method of forming composite particles while generating a polyester resin by an elongation reaction and/or crosslinking reaction between the prepolymer and a curing agent will be described.
In this method, an aqueous medium (aqueous phase) is prepared, an oil phase containing the materials for the toner base particles is prepared, the toner base particle materials are emulsified or dispersed, and the organic solvent is removed.

- Preparation of aqueous medium (aqueous phase) -
The aqueous medium can be prepared, for example, by dispersing resin fine particles in the aqueous medium.
The amount of resin particles added to the aqueous medium is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.5 to 10 parts by mass per 100 parts by mass of the aqueous medium.

The aqueous medium is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include water, a solvent miscible with water, and a mixture thereof. Among these, water is preferred. These may be used alone or in combination of two or more.
The water-miscible solvent is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include alcohol, dimethylformamide, tetrahydrofuran, cellosolves, and lower ketones.
Examples of the alcohol include methanol, isopropanol, and ethylene glycol.
Examples of the lower ketones include acetone and methyl ethyl ketone.

- Preparation of oil phase -
The oil phase can be prepared by dissolving or dispersing the materials for the toner base particles, which contain a binder resin, a colorant, and a wax, and further contain a curing agent, etc., as needed, in an organic solvent.
The curing agent is not particularly limited and can be appropriately selected depending on the purpose. For example, isophoronediamine (IPDA) can be used.

The organic solvent is not particularly limited and can be appropriately selected depending on the purpose, but organic solvents having a boiling point of less than 150° C. are preferred in terms of ease of removal.
Examples of the organic solvent having a boiling point of less than 150° C. include toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, etc. Among these, ethyl acetate, toluene, xylene, benzene, methylene chloride, 1,2-dichloroethane, chloroform, carbon tetrachloride, etc. are preferred, and ethyl acetate is more preferred.
These may be used alone or in combination of two or more.

-Emulsification or dispersion-
The toner materials can be emulsified or dispersed by dispersing an oil phase containing the materials for the toner base particles in the aqueous medium, and during the emulsification or dispersion of the toner materials, the curing agent and the prepolymer can undergo an elongation reaction and/or a crosslinking reaction.

The reaction conditions (reaction time, reaction temperature) for producing the prepolymer are not particularly limited and can be appropriately selected depending on the combination of the curing agent and the prepolymer.
The reaction time is preferably 10 minutes to 40 hours, more preferably 2 to 24 hours.
The reaction temperature is preferably 0°C to 150°C, more preferably 40°C to 98°C.

There are no particular limitations on the method for stably forming a dispersion containing the prepolymer in the aqueous medium, and it can be selected appropriately depending on the purpose. For example, there is a method in which an oil phase prepared by dissolving or dispersing toner materials in a solvent is added to the aqueous medium phase, and the mixture is dispersed by shear force.

The disperser used for the dispersion is not particularly limited and can be selected appropriately depending on the purpose. Examples include low-speed shear dispersers, high-speed shear dispersers, friction dispersers, high-pressure jet dispersers, and ultrasonic dispersers. Of these, high-speed shear dispersers are preferred because they can control the particle size of the dispersed material (oil droplets) to 2 μm to 20 μm.

When the high-speed shear disperser is used, conditions such as the rotation speed, dispersing time, and dispersing temperature can be appropriately selected depending on the purpose.
The rotation speed is preferably 1,000 rpm to 30,000 rpm, and more preferably 5,000 rpm to 20,000 rpm.
In the case of a batch method, the dispersion time is preferably 0.1 to 5 minutes.
The dispersion temperature under pressure is preferably 0° C. to 150° C., more preferably 40° C. to 98° C. Generally, the higher the dispersion temperature, the easier the dispersion.

The amount of the aqueous medium used when emulsifying or dispersing the toner materials is not particularly limited and can be appropriately selected depending on the purpose. However, the amount is preferably 50 parts by mass to 2,000 parts by mass, and more preferably 100 parts by mass to 1,000 parts by mass, relative to 100 parts by mass of the toner materials.
When the amount of the aqueous medium used is 50 parts by mass or more, the dispersion state of the toner materials becomes poor, and the problem of not being able to obtain toner base particles of a predetermined particle size can be solved.When the amount of the aqueous medium used is 2,000 parts by mass or less, the problem of high production costs can be solved.

When the oil phase containing the toner materials is emulsified or dispersed, it is preferable to use a dispersant from the viewpoint of stabilizing the dispersion of oil droplets and the like, forming a desired shape, and sharpening the particle size distribution.
The dispersant is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include surfactants, poorly water-soluble inorganic compound dispersants, polymeric protective colloids, etc. Among these, surfactants are preferred.
These may be used alone or in combination of two or more.

The surfactant used as the dispersant is not particularly limited and can be appropriately selected depending on the purpose. For example, anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, etc. can be used.
Examples of anionic surfactants used as the dispersant include alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters, etc. Among these, those having a fluoroalkyl group are preferred.

- Removal of organic solvents -
The method for removing the organic solvent from the dispersion liquid such as the emulsified slurry is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include a method in which the temperature of the entire reaction system is gradually increased to evaporate the organic solvent in the oil droplets, and a method in which the dispersion liquid is sprayed into a dry atmosphere to remove the organic solvent in the oil droplets.
Once the organic solvent is removed, composite particles are formed.

<Removal process>
The removal step is a step of removing at least a portion of the resin fine particles from the composite particles, and it is preferable to remove a portion or all of the shell resin (resin (b1)) in the resin fine particles.
The step of removing at least a portion of the resin fine particles can be, for example, a washing step of washing the composite particles. Therefore, the removing step can also be called a washing step.

In the washing step, examples of a method for removing a part or all of the resin (b1) include a method for removing a part or all of the resin (b1) by a chemical method.
The chemical method is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a step of washing the composite particles with a basic aqueous solution, which can dissolve part or all of the shell resin (b1).

The basic aqueous solution is not particularly limited as long as it is basic and can be appropriately selected depending on the purpose, and examples thereof include aqueous solutions of alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, ammonia, etc. Among these, potassium hydroxide and sodium hydroxide are preferred from the viewpoint of facilitating dissolution of the shell resin (b1).
These may be used alone or in combination of two or more.
The pH of the basic aqueous solution is preferably 8 to 14, more preferably 10 to 12.

The mixing of the composite particles with the basic aqueous solution in the washing step can be carried out by, for example, adding the basic aqueous solution dropwise to the composite slurry under stirring.
After the basic aqueous solution is added dropwise, an acidic aqueous solution may be added dropwise to neutralize the solution.

<Other processes>
The other steps are not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include a drying step and a classification step.
The drying step is not particularly limited as long as it can remove the solvent from the composite particles, and can be appropriately selected depending on the purpose.
The classification step is not particularly limited and can be appropriately selected depending on the purpose. For example, the classification step may be performed by removing fine particles in a liquid using a cyclone, decanter, centrifugation, or the like, or the classification operation may be performed after drying.

The composite particles obtained by the composite particle forming step, the removing step, and the other steps may be mixed with particles of the external additive, the charge control agent, etc. In this case, by applying a mechanical impact force, it is possible to prevent the particles of the external additive, etc. from being detached from the surface of the toner base particles.
The method for applying the mechanical impact force is not particularly limited and can be appropriately selected depending on the purpose. Examples include a method for applying an impact force to the mixture using blades rotating at high speed, and a method for introducing the mixture into a high-speed airflow and accelerating it to cause particles to collide with each other or with an appropriate collision plate.

The equipment used in the method of applying the mechanical impact force is not particularly limited and can be selected appropriately depending on the purpose. Examples include an Ang Mill (manufactured by Hosokawa Micron Corporation), an I-type Mill (manufactured by Nippon Pneumatic Co., Ltd.) modified to reduce the grinding air pressure, a Hybridization System (manufactured by Nara Machinery Works, Ltd.), a Kryptron System (manufactured by Kawasaki Heavy Industries, Ltd.), and an automatic mortar.

(Toner storage unit)
The toner storage unit in the present invention refers to a unit having a function of storing toner and storing the toner of the present invention. Examples of the toner storage unit include a toner storage container, a developing unit, and a process cartridge.
The toner container refers to a container that contains the toner of the present invention.
The developing device has a means for containing and developing the toner of the present invention.
The process cartridge is a cartridge that integrates at least an image carrier and a developing unit, contains the toner of the present invention, and is detachably mountable to an image forming apparatus. The process cartridge may further include at least one selected from a charging unit, an exposure unit, and a cleaning unit.

The process cartridge according to the present invention will now be described with reference to the drawings. The present invention is not limited to the embodiments shown below, and other modifications, additions, corrections, deletions, and other changes may be made within the scope of what one skilled in the art could conceive. Any aspect that achieves the functions and effects of the present invention is within the scope of the present invention.

One embodiment of the process cartridge is shown in Fig. 2. As shown in Fig. 2, the process cartridge of this embodiment incorporates a latent image carrier 101, a charging device 102, a developing device 104, and a cleaning unit 107, and may further include other means as necessary. In Fig. 2, reference numeral 103 denotes exposure from an exposure device, and reference numeral 105 denotes recording paper.
The latent image carrier 101 may be the same as an electrostatic latent image carrier in an image forming apparatus described later, and the charging device 102 may be any charging member.
In the image forming process using the process cartridge shown in FIG. 2, the latent image carrier 101 rotates clockwise in FIG. 2, and an electrostatic latent image corresponding to the exposed image is formed on its surface by charging with a charging device 102 and exposure 103 with an exposure means (not shown).
The electrostatic latent image is developed with toner by a developing device 104, and the toner development is transferred to recording paper 105 by a transfer roller 108 and printed out. Next, the surface of the latent image carrier after the image transfer is cleaned by a cleaning unit 107, and further discharged by a discharge means (not shown), and the above-mentioned operations are repeated again.

(Image forming apparatus and image forming method)
The image forming apparatus of the present invention preferably has the above-mentioned toner storage unit, an electrostatic latent image carrier, an electrostatic latent image forming means, and a developing means, and further has other means as required.
The image forming method according to the present invention includes at least an electrostatic latent image forming step and a development step, and may further include other steps as required.

<Electrostatic Latent Image Carrier>
The material, structure and size of the electrostatic latent image bearing member are not particularly limited, and can be appropriately selected from known materials.
Examples of materials for the electrostatic latent image bearing member include inorganic photoconductors such as amorphous silicon and selenium, and organic photoconductors such as polysilane and phthalopolymethine, etc. Among these, amorphous silicon is preferred in terms of long life.
The linear speed of the electrostatic latent image bearing member is preferably 300 mm/s or more.

<Electrostatic Latent Image Forming Unit and Electrostatic Latent Image Forming Process>
The electrostatic latent image forming means is not particularly limited as long as it is a means for forming an electrostatic latent image on the electrostatic latent image carrier, and can be appropriately selected depending on the purpose. For example, it may be a means having at least a charging member that charges the surface of the electrostatic latent image carrier, and an exposure member that exposes the surface of the electrostatic latent image carrier to light in an imagewise manner.
The electrostatic latent image forming step is not particularly limited as long as it is a step of forming an electrostatic latent image on the electrostatic latent image bearing member, and can be appropriately selected depending on the purpose. For example, the electrostatic latent image forming step can be performed by charging the surface of the electrostatic latent image bearing member and then exposing it to light in an imagewise manner, using the electrostatic latent image forming unit.

- Charging member and charging -
The charging member is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include known contact chargers equipped with a conductive or semiconductive roller, brush, film, rubber blade, etc., and non-contact chargers utilizing corona discharge such as corotrons and scorotrons, etc. Among these, it is preferable to use a contact-type charging member, since this allows for an image forming apparatus in which the amount of ozone generated from the charging member is reduced.
The shape of the charging member may be a roller, a magnetic brush, a fur brush, or any other shape, and can be selected according to the specifications and shape of the image forming apparatus.

The charging can be performed, for example, by applying a voltage to the surface of the electrostatic latent image carrier using the charging member.

<<Exposure Member and Exposure>>
The exposure member is not particularly limited as long as it can expose the surface of the electrostatic latent image carrier charged by the charging member in the shape of an image to be formed, and can be appropriately selected depending on the purpose. Examples of the exposure member include various exposure members such as a copying optical system, a rod lens array system, a laser optical system, and a liquid crystal shutter optical system.

The light source used in the exposure member is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include general light-emitting materials such as fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light-emitting diodes (LEDs), semiconductor lasers (LDs), and electroluminescence (EL).
In addition, the light source used in the exposure member may also use various filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter in order to irradiate only light in a desired wavelength range.

The exposure can be carried out, for example, by exposing the surface of the electrostatic latent image bearing member to light in an imagewise manner using the exposure member.
In the present invention, a backlight system may be employed in which exposure is performed imagewise from the back side of the electrostatic latent image bearing member.

<Developing means and developing process>
The developing unit is not particularly limited as long as it is a developing unit that has a toner that develops the electrostatic latent image formed on the electrostatic latent image carrier to form a toner image that is a visible image, and can be appropriately selected depending on the purpose.
The developing step is not particularly limited as long as it is a step of forming a toner image, which is a visible image, by developing the electrostatic latent image formed on the electrostatic latent image carrier with a toner, and can be appropriately selected depending on the purpose. For example, the developing step can be performed by the developing unit.
The developing means is preferably a developing device having an agitator that frictionally agitates the toner to charge it, a magnetic field generating means fixed inside, and a rotatable developer carrier that carries a developer containing the toner on its surface.

<Other means and other steps>
Examples of the other means include a transfer means, a fixing means, a cleaning means, a discharging means, and a recycling means.
Examples of the other steps include a transfer step, a fixing step, a cleaning step, a charge removal step, and a recycling step.

-Transfer means and transfer process-
The transfer means is not particularly limited as long as it is a means for transferring a visible image onto a recording medium, and can be selected appropriately depending on the purpose. However, a preferred embodiment has a primary transfer means for transferring the visible image onto an intermediate transfer body to form a composite transfer image, and a secondary transfer means for transferring the composite transfer image onto a recording medium.
The transfer step is not particularly limited as long as it is a step of transferring a visible image onto a recording medium, and can be appropriately selected depending on the purpose. However, a preferred embodiment is one in which an intermediate transfer body is used, a visible image is primarily transferred onto the intermediate transfer body, and then the visible image is secondarily transferred onto a recording medium.
The transfer step can be carried out by, for example, charging the visible image on the photosensitive member using a transfer charger, and can be carried out by the transfer unit.

Here, when the image to be secondarily transferred onto the recording medium is a color image made up of toners of multiple colors, the transfer means can be configured to sequentially overlay toners of each color on the intermediate transfer body to form an image on the intermediate transfer body, and the intermediate transfer means can secondarily transfer the image on the intermediate transfer body onto the recording medium all at once.
The intermediate transfer member is not particularly limited and can be appropriately selected from known transfer members depending on the purpose, and a suitable example is a transfer belt.

The transfer means (the primary transfer means and the secondary transfer means) preferably includes at least a transfer device that peels and charges the visible image formed on the photosensitive member onto the recording medium.
Examples of the transfer device include a corona transfer device using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device.
The recording medium is typically plain paper, but is not particularly limited as long as it is capable of transferring an unfixed image after development, and can be selected appropriately depending on the purpose. For example, a PET base for an overhead projector can also be used.

- Fixing means and fixing process -
The fixing means is not particularly limited as long as it is a means for fixing the transferred image transferred onto the recording medium, and can be appropriately selected depending on the purpose. For example, a known heating and pressing member is preferred.
Examples of the heating and pressing member include a combination of a heating roller and a pressure roller, and a combination of a heating roller, a pressure roller and an endless belt.
The fixing step is not particularly limited as long as it is a step of fixing the visible image transferred to the recording medium, and can be appropriately selected depending on the purpose. For example, the fixing step may be performed for each color toner transferred to the recording medium, or may be performed simultaneously for each color toner in a stacked state. The fixing step can be performed by the fixing unit.
The heating temperature in the heating and pressing member is preferably 80°C to 200°C.

In the present invention, depending on the purpose, a known optical fixing device may be used together with or instead of the fixing means.
The surface pressure in the fixing step is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10 N/cm ² to 80 N/cm ² .

<<Cleaning means and cleaning process>>
The cleaning means is not particularly limited as long as it can remove the toner remaining on the photosensitive member, and can be appropriately selected depending on the purpose. Examples of the cleaning means include a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, a blade cleaner, a brush cleaner, and a web cleaner.
The cleaning step is not particularly limited as long as it can remove the toner remaining on the photoreceptor, and can be appropriately selected depending on the purpose. For example, the cleaning step can be performed by the cleaning unit.

-Static removal means and static removal process-
The discharging means is not particularly limited as long as it is a means for discharging the photosensitive member by applying a discharging bias to the photosensitive member, and can be appropriately selected depending on the purpose. For example, a discharging lamp can be used.
The charge-eliminating step is not particularly limited as long as it is a step of applying a charge-eliminating bias to the photosensitive member to eliminate charges, and can be appropriately selected depending on the purpose. For example, it can be performed by the charge-eliminating unit.

-Recycling methods and processes-
The recycling means is not particularly limited as long as it is a means for recycling the toner removed by the cleaning step into the developing device, and can be appropriately selected depending on the purpose. For example, known conveying means can be used.
The recycling step is not particularly limited as long as it is a step of recycling the toner removed by the cleaning step into the developing device, and can be appropriately selected depending on the purpose. For example, it can be performed by the recycling means.

The image forming apparatus according to the present invention will now be described with reference to the drawings. Note that the present invention is not limited to the embodiments shown below, and other modifications, additions, corrections, deletions, and other changes may be made within the scope of what one skilled in the art could conceive. Any aspect that achieves the functions and effects of the present invention is within the scope of the present invention.

One embodiment of the method for forming an image using the image forming apparatus of the present invention will be described with reference to Fig. 3. Note that although a printer is shown as an example of the image forming apparatus of this embodiment, the image forming apparatus of the present invention is not particularly limited as long as it is capable of forming an image using toner in a copier, facsimile, multifunction machine, or the like.
The image forming apparatus includes a paper feed section 210 , a conveying section 220 , an image forming section 230 , a transfer section 240 , and a fixing unit 250 .
The paper feed section 210 includes a paper feed cassette 211 in which paper sheets P to be fed are stacked, and a paper feed roller 212 that feeds the paper sheets P stacked in the paper feed cassette 211 one by one.

The transport unit 220 includes a roller 221 that transports the paper P fed by the paper feed roller 212 toward the transfer unit 240, a pair of timing rollers 222 that hold the leading edge of the paper P transported by the roller 221 and wait, sending the paper to the transfer unit 240 at a predetermined timing, and a paper discharge roller 223 that discharges the paper P with the fixed color toner image onto the paper discharge tray 224.

The image forming section 230 includes, at predetermined intervals from left to right in the figure, an image forming unit 180Y that forms an image using a developer containing yellow toner, an image forming unit 180C that uses a developer containing cyan toner, an image forming unit 180M that uses a developer containing magenta toner, an image forming unit 180K that uses a developer containing black toner, and an exposure device 233.
The image forming units 180 (180Y, 180C, 180M, 180K) are arranged to be rotatable clockwise in the drawing, and include photosensitive drums 231 (231Y, 231C, 231M, 231K) on which electrostatic latent images and toner images are formed, chargers 232 (232Y, 232C, 232M, 232K) that uniformly charge the surfaces of the photosensitive drums 231 (231Y, 231C, 231M, 231K), and cleaners 236 (236Y, 236C, 236M, 236K) that remove toner remaining on the surfaces of the photosensitive drums 231 (231Y, 231C, 231M, 231K).
In addition, the image forming units 180 (180Y, 180C, 180M, 180K) are equipped with toner bottles 234 (234Y, 234C, 234M, 234K) that contain toner of each color, and sub-hoppers 160 (160Y, 160C, 160M, 160K) that replenish the toner supplied from the toner bottles 234 (234Y, 234C, 234M, 234K).
It should be noted that when referring to any one of the image forming units 180 (180Y, 180C, 180M, 180K), it will be referred to as the image forming unit.

The exposure unit 233 emits laser light L from a light source 233 a based on image information, and reflects the light on a polygon mirror 233 b ( 233 b Y, 233 b C, 233 b M, 233 b K) that is driven to rotate by a motor, thereby irradiating the photosensitive drum 231 with the light.
The developer contains toner and carrier. The four image forming units 180 (180Y, 180C, 180M, 180K) have substantially the same mechanical configuration, except for the developer used.

The transfer unit 240 includes a drive roller 241, a driven roller 242, an intermediate transfer belt 243 that can rotate counterclockwise in FIG. 3 as the drive roller 241 is driven, primary transfer rollers 244 (244Y, 244C, 244M, 244K) that are arranged opposite the photosensitive drums 231 (231Y, 231C, 231M, 231K) across the intermediate transfer belt 243, and secondary opposing rollers 245 and 246 that are arranged opposite each other across the intermediate transfer belt 243 at the position where the toner image is transferred to paper.

The fixing unit 250 has an internal heater and a pressure roller 252 that forms a nip by rotatably pressing a fixing belt 251 that heats the paper P against the fixing belt 251. This applies heat and pressure to the color toner image on the paper P, fixing the color toner image. The paper P with the fixed color toner image is discharged to a paper discharge tray 224 by a paper discharge roller 223, completing the image formation process.

Examples of the present invention are described below, but the present invention is not limited to these examples in any way.

(Production Example 1)
<Synthesis of amorphous polyester (low molecular weight polyester) resin>
The following materials were placed in a 5-liter four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, and the mixture was reacted at 230° C. under atmospheric pressure for 7 hours.
-material-
- 229 parts by mass of bisphenol A ethylene oxide 2-mol adduct - 529 parts by mass of bisphenol A propylene oxide 2-mol adduct - 208 parts by mass of terephthalic acid - 46 parts by mass of adipic acid - 2 parts by mass of dibutyltin oxide Further, after reacting for 4 hours under a reduced pressure of 10 mmHg to 15 mmHg, 44 parts by mass of trimellitic anhydride was added to the reaction vessel and reacted for 2 hours at 180°C under normal pressure to obtain an amorphous polyester (low molecular weight polyester) resin.

(Production Example 2)
<Synthesis of crystalline polyester resin>
The following materials were placed in a 5-liter four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, and the mixture was reacted at 160° C. for 5 hours.
-material-
1,6-hexanediol 2,300 parts by mass Fumaric acid 2,530 parts by mass Trimellitic anhydride 291 parts by mass Hydroquinone 4.9 parts by mass Further, the temperature was raised to 200°C and the reaction was carried out for 1 hour, and then the reaction was carried out for 1 hour at 8.3 kPa to obtain a [crystalline polyester resin].

(Production Example 3)
<Synthesis of Polyester Prepolymer>
The following materials were placed in a reaction vessel equipped with a condenser, a stirrer, and a nitrogen inlet tube, and the mixture was reacted at 230° C. under atmospheric pressure for 8 hours.
-material-
Bisphenol A ethylene oxide 2-mol adduct 682 parts by mass Bisphenol A propylene oxide 2-mol adduct 81 parts by mass Terephthalic acid 283 parts by mass Trimellitic anhydride 22 parts by mass Dibutyltin oxide 2 parts by mass Further, the mixture was reacted for 5 hours under a reduced pressure of 10 mmHg to 15 mmHg to obtain an intermediate polyester.
The resulting [intermediate polyester] had a number average molecular weight Mn of 2,100, a weight average molecular weight Mw of 9,500, a glass transition temperature Tg of 55° C., an acid value of 0.5 KOHmg/g, and a hydroxyl value of 51 KOHmg/g.
Next, 410 parts by mass of the [intermediate polyester], 89 parts by mass of isophorone diisocyanate, and 500 parts by mass of ethyl acetate were placed in a reaction vessel equipped with a condenser, a stirrer, and a nitrogen inlet tube, and the mixture was allowed to react at 100°C for 5 hours to obtain a [polyester prepolymer].

(Production Example 4)
<Production of Aqueous Dispersion (W0-1) of Resin Fine Particles (A-1)>
The following materials were added to a reaction vessel equipped with a stirrer, a heating/cooling device, and a thermometer, and the mixture was stirred at 200 rpm to homogenize.
-material-
Water 3710 parts by mass Polyoxyethylene-1-(allyloxymethyl) alkyl ether ammonium sulfate (Aqualon KH-1025, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) 200 parts by mass The homogenized mixture was heated to raise the system temperature to 75°C, and then 90 parts by mass of a 10% by mass aqueous solution of ammonium persulfate was added, and then the following materials (mixture) were added dropwise over 4 hours.
-Materials (mixture)-
Styrene 450 parts by mass Butyl acrylate 250 parts by mass Methacrylic acid 300 parts by mass After the dropwise addition, the mixture was aged at 75°C for 4 hours to obtain a resin fine particle (A-1) dispersion (W0-1) containing a resin (a1) that is a polymer in which the monomers and polyoxyethylene-1-(allyloxymethyl) alkyl ether sulfate ester ammonium are copolymerized.
The volume average primary particle size of the fine particles in the aqueous dispersion (W0-1) of resin fine particles (A-1) was measured with a dynamic light scattering particle size distribution measuring device (LB) and was found to be 15 nm.
A part of the aqueous dispersion (W0-1) of resin fine particles (A-1) was dried to isolate resin (a1).
The resin (a1) had a glass transition temperature (Tg) of 53° C. and an acid value of 195 mg KOH/g.

(Production Example 5)
<Production of Aqueous Dispersion (W0-2) of Resin Fine Particles (A-2)>
The following materials were added to a reaction vessel equipped with a stirrer, a heating/cooling device, and a thermometer, and the mixture was stirred at 200 rpm to homogenize.
-material-
Water 3,760 parts by mass Polyoxyethylene-1-(allyloxymethyl) alkyl ether sulfate ester ammonium (Aqualon KH-1025, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) 150 parts by mass The homogenized mixture was heated to raise the system temperature to 75°C, and then 90 parts by mass of a 10% by mass aqueous solution of ammonium persulfate was added, and then the following materials (mixture) were added dropwise over 4 hours.
-Materials (mixture)-
- 430 parts by mass of styrene - 270 parts by mass of butyl acrylate - 300 parts by mass of methacrylic acid After the dropwise addition, the mixture was aged at 75°C for 4 hours to obtain [aqueous dispersion of resin fine particles (A-2) (W0-2)] containing resin (a2), which is a polymer in which the monomers and polyoxyethylene-1-(allyloxymethyl) alkyl ether sulfate ester ammonium have been copolymerized.
The volume average primary particle diameter of the fine particles in the aqueous dispersion (W0-2) of resin fine particles (A-2) was measured in the same manner as in Production Example 4 and was found to be 30 nm.
A part of the aqueous dispersion (W0-2) of resin fine particles (A-2) was dried to isolate resin (a2).
The resin (a2) had a glass transition temperature (Tg) of 53° C. and an acid value of 195 mg KOH/g.

(Production Example 6)
<Production of Aqueous Dispersion (W0-3) of Resin Fine Particles (A-3)>
The following materials were added to a reaction vessel equipped with a stirrer, a heating/cooling device, and a thermometer, and the mixture was stirred at 200 rpm to homogenize.
-material-
Water 3,810 parts by mass Polyoxyethylene-1-(allyloxymethyl) alkyl ether ammonium sulfate (Aqualon KH-1025, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) 100 parts by mass After heating to raise the system temperature to 75°C, 90 parts by mass of a 10% by mass aqueous solution of ammonium persulfate was added, and then the following materials (mixture) were added dropwise over 4 hours.
-Materials (mixture)-
- 400 parts by mass of styrene - 300 parts by mass of butyl acrylate - 300 parts by mass of methacrylic acid After the dropwise addition, the mixture was aged at 75°C for 4 hours to obtain [aqueous dispersion of resin fine particles (A-3) (W0-3)] containing resin (a3), which is a polymer in which the monomers and polyoxyethylene-1-(allyloxymethyl) alkyl ether sulfate ester ammonium have been copolymerized.
The volume average primary particle diameter of the fine particles in the aqueous dispersion (W0-3) of resin fine particles (A-3) was measured in the same manner as in Production Example 4 and was found to be 45 nm.
A part of the aqueous dispersion (W0-3) of resin fine particles (A-3) was dried to isolate resin (a3).
The resin (a3) had a glass transition temperature (Tg) of 53° C. and an acid value of 195 mg KOH/g.

(Production Example 7)
<Production of Aqueous Dispersion (W-1) of Resin Fine Particles (B-1)>
The following materials were placed in a reaction vessel equipped with a stirrer, a heating/cooling device, and a thermometer, and after 0.267 parts by mass of tertiary butyl hydroperoxide (Perbutyl H, manufactured by NOF Corporation) was added, the mixture was heated until the temperature inside the system reached 70°C.
-material-
Resin fine particle (A-1) aqueous dispersion (W0-1) 667 parts by mass Water 248 parts by mass Next, the following materials (mixture) were added dropwise over 2 hours.
-Materials (mixture)-
- 43.3 parts by mass of styrene - 17.5 parts by mass of butyl acrylate - 5.8 parts by mass of 2-ethylhexyl acrylate - 18.0 parts by mass of 1 wt % aqueous ascorbic acid solution After the dropwise addition, the mixture was aged at 70°C for 4 hours to obtain an aqueous dispersion (W-1) of resin fine particles (B-1), in which the resin (a1-1), which is a polymer obtained by copolymerizing the monomers, and the resin (a1) are contained as constituent components in the same particle, using the resin (a1) in the aqueous dispersion (W0-1) of resin fine particles (A-1) as a seed.
The volume average primary particle diameter of the resin fine particles (B-1) in the resin fine particle (B-1) aqueous dispersion (W-1) was measured in the same manner as in Production Example 4 and was found to be 17 nm.

It was confirmed as follows that the aqueous dispersion (W-1) of resin fine particles (B-1) contained resin fine particles (B-1) containing resin (a1-1) and resin (a1) as constituent components in the same particle.
Specifically, 2 parts by mass of gelatin (Cook Gelatin, manufactured by Morinaga Milk Industry Co., Ltd.) was added to and dissolved in 15 parts by mass of water heated to 95°C to 100°C, and the gelatin solution was air-cooled to 40°C. The aqueous dispersion (W-1) of resin microparticles (B-1) was then mixed with the gelatin solution at a mass ratio of 1:1, thoroughly stirred, and then cooled at 10°C for 1 hour to produce a hardened gel.
This gel was sliced into 80 nm thick sections using an ultramicrotome (Ultramicrotome UC7, FC7, manufactured by Leica Microsystems) while maintaining the temperature at −80°C. The sections were then subjected to vapor staining with a 2% by mass aqueous solution of ruthenium tetroxide for 5 minutes, and then observed with a transmission electron microscope (Hitachi Technologies, Ltd., H-7100) for confirmation.

(Production Example 8)
<Production of Aqueous Dispersion (W-2) of Resin Fine Particles (B-2)>
The following materials were placed in a reaction vessel equipped with a stirrer, a heating/cooling device, and a thermometer, and after 0.267 parts by mass of tertiary butyl hydroperoxide (Perbutyl H, manufactured by NOF Corporation) was added, the mixture was heated until the temperature inside the system reached 70°C.
-material-
Resin fine particle (A-1) aqueous dispersion (W0-1) 667 parts by mass Water 248 parts by mass Next, the following materials (mixture) were added dropwise over 2 hours.
-Materials (mixture)-
- 43.3 parts by mass of styrene - 23.3 parts by mass of butyl acrylate - 18.0 parts by mass of 1 wt % aqueous ascorbic acid solution After the dropwise addition, the mixture was aged at 70°C for 4 hours to obtain an aqueous dispersion (W-2) of resin fine particles (B-2), in which the resin (a1) and the resin (a1-2), which are polymers obtained by copolymerization of the monomers, are contained as constituent components in the same particle, using the resin (a1) in the aqueous dispersion (W0-1) of resin fine particles (A-1) as a seed.
The volume average primary particle diameter of the resin fine particles (B-2) in the resin fine particle (B-2) aqueous dispersion (W-2) was measured in the same manner as in Production Example 4 and was found to be 17 nm.
It was confirmed by the same method as in Production Example 7 that the resin fine particle (B-2) aqueous dispersion (W-2) contained resin fine particles (B-2) containing resin (a1) and resin (a1-2) as constituent components in the same particle.

(Production Example 9)
<Production of Aqueous Dispersion (W-3) of Resin Fine Particles (B-3)>
The following materials were placed in a reaction vessel equipped with a stirrer, a heating/cooling device, and a thermometer, and after 0.267 parts by mass of tertiary butyl hydroperoxide (Perbutyl H, manufactured by NOF Corporation) was added, the mixture was heated until the temperature inside the system reached 70°C.
-material-
Resin fine particle (A-1) aqueous dispersion (W0-1) 667 parts by mass Water 248 parts by mass Next, a mixed liquid of the following materials was added dropwise over 2 hours.
-Materials (mixture)-
Styrene 43.3 parts by mass 2-ethylhexyl acrylate 23.3 parts by mass 1 wt % aqueous ascorbic acid solution 18.0 parts by mass After the dropwise addition, the mixture was aged at 70°C for 4 hours to obtain an aqueous dispersion (W-3) of resin fine particles (B-3), which contains, as constituent components, resin (a1) and resin (a1-3), a polymer obtained by copolymerization of the monomers, in the same particle, using resin (a1) in the aqueous dispersion (W0-1) of resin fine particles (A-1) as a seed.
The volume average primary particle diameter of the resin fine particles (B-3) in the resin fine particle (B-3) aqueous dispersion (W-3) was measured in the same manner as in Production Example 4 and was found to be 17 nm.
It was confirmed by the same method as in Production Example 7 that the aqueous dispersion (W-3) of resin fine particles (B-3) contained resin fine particles (B-3) containing resin (a1) and resin (a1-3) as constituent components in the same particle.

(Production Example 10)
<Production of Aqueous Dispersion (W-4) of Resin Fine Particles (B-4)>
The following materials were placed in a reaction vessel equipped with a stirrer, a heating/cooling device, and a thermometer, and after 0.267 parts by mass of tertiary butyl hydroperoxide (Perbutyl H, manufactured by NOF Corporation) was added, the mixture was heated until the temperature inside the system reached 70°C.
-material-
Resin fine particle (A-2) aqueous dispersion (W0-2) 667 parts by mass Water 248 parts by mass Next, the following materials (mixture) were added dropwise over 2 hours.
-Materials (mixture)-
- 43.3 parts by mass of styrene - 17.5 parts by mass of butyl acrylate - 5.8 parts by mass of 2-ethylhexyl acrylate - 18.0 parts by mass of 1 wt % aqueous ascorbic acid solution After the dropwise addition, the mixture was aged at 70°C for 4 hours to obtain an aqueous dispersion (W-4) of resin fine particles (B-4), in which the resin (a2-1), which is a polymer obtained by copolymerizing the monomers, and the resin (a2) are contained as constituent components in the same particle, using the resin (a2) in the aqueous dispersion (W0-2) of resin fine particles (A-2) as a seed.
The volume average primary particle diameter of the resin fine particles (B-4) in the resin fine particle (B-4) aqueous dispersion (W-4) was measured in the same manner as in Production Example 4 and was found to be 34 nm.
It was confirmed by the same method as in Production Example 7 that the resin fine particle (B-4) aqueous dispersion (W-4) contained resin fine particles (B-4) containing resin (a2-1) and resin (a2) as constituent components in the same particle.

(Production Example 11)
<Production of Aqueous Dispersion (W-5) of Resin Fine Particles (B-5)>
The following materials were placed in a reaction vessel equipped with a stirrer, a heating/cooling device, and a thermometer, and after 0.267 parts by mass of tertiary butyl hydroperoxide (Perbutyl H, manufactured by NOF Corporation) was added, the mixture was heated until the temperature inside the system reached 70°C.
-material-
Resin fine particle (A-3) aqueous dispersion (W0-3) 667 parts by mass Water 248 parts by mass Next, the following materials (mixture) were added dropwise over 2 hours.
-Materials (mixture)-
- 43.3 parts by mass of styrene - 23.3 parts by mass of butyl acrylate - 18.0 parts by mass of 1 wt % aqueous ascorbic acid solution After the dropwise addition, the mixture was aged at 70°C for 4 hours to obtain an aqueous dispersion (W-5) of resin fine particles (B-5), in which the resin (a3) in the aqueous dispersion (W0-3) of resin fine particles (A-3) was used as a seed and contained, as constituent components, the resin (a3-1), which is a polymer obtained by copolymerizing the monomers, and the resin (a3) in the same particle.
The volume average primary particle diameter of the resin fine particles (B-5) in the resin fine particle (B-5) aqueous dispersion (W-5) was measured in the same manner as in Production Example 4 and was found to be 52 nm.
It was confirmed by the same method as in Production Example 7 that the resin fine particle (B-5) aqueous dispersion (W-5) contained resin fine particles (B-5) containing resin (a3-1) and resin (a3) as constituent components within the same particle.

(Production Example 12)
<Production of Aqueous Dispersions (W-6) of Resin Fine Particles (B-6) to (W-9) of Resin Fine Particles (B-9)>
In Production Example 11, the entire amount of butyl acrylate was changed to 23.3 parts by mass to 2-ethylhexyl acrylate to produce a resin microparticle (B-6) aqueous dispersion (W-6), a resin microparticle (B-7) aqueous dispersion (W-7) was produced by changing 75% of 23.3 parts by mass of butyl acrylate to 2-ethylhexyl acrylate, a resin microparticle (B-8) aqueous dispersion (W-8) was produced by changing 50% of 23.3 parts by mass of butyl acrylate to 2-ethylhexyl acrylate, and a resin microparticle (B-9) aqueous dispersion (W-9) was produced by changing 25% of 23.3 parts by mass of butyl acrylate to 2-ethylhexyl acrylate.
The volume average primary particle diameters of the aqueous dispersions (W-6) of resin microparticles (B-6) to (W-9) of resin microparticles (B-9) were measured in the same manner as in Production Example 4. The values were 56 nm for the resin microparticles (B-6), 54 nm for the resin microparticles (B-7), 54 nm for the resin microparticles (B-8), and 52 nm for the resin microparticles (B-9).
It was confirmed by the same method as in Production Example 7 that the aqueous dispersions (W-6) of resin microparticles (B-6) to (W-9) of resin microparticles (B-9) contain resins (a3-2) to (a3-5), which are polymers obtained by copolymerizing the monomers using the resin (a3) in (W0-3) as a seed, and resin microparticles (B-6) to (B-9) containing the resin (a3) as a constituent component within the same particle.

(Production Example 13)
<Production of Polyester Resin Fine Particles>
The polyester resin was prepared as follows.
[Production of Polyester Resin]
A mixture of 1,600 parts of terephthalic acid, 633 parts of isophthalic acid, 1,149 parts of ethylene glycol, and 1,510 parts of neopentyl glycol was heated in an autoclave at 260 ° C. for 5 hours to carry out an esterification reaction. Next, 0.262 parts of germanium dioxide catalyst was added, and the temperature of the system was raised to 280 ° C. over 30 minutes. The pressure of the system was gradually reduced to 0.1 Torr after 1 hour. Under these conditions, the polycondensation reaction was further continued, and after 5 hours, the system was returned to normal pressure with nitrogen gas, the temperature of the system was lowered, and when the temperature reached 260 ° C., 50 parts of isophthalic acid and 26.6 parts of trimellitic anhydride were added, and the mixture was stirred at 255 ° C. for 30 minutes and discharged into a sheet. Next, after sufficient cooling to room temperature, the mixture was crushed with a crusher and a sieve was used to obtain a fraction of [polyester resin] with a mesh size of 1 to 6 mm.
[Production of Crystalline Polyester Resin Particle Dispersion]
A 2-L jacketed glass vessel was charged with 200 parts of polyester resin, 35 parts of ethylene glycol mono-n-butyl ether, 450 parts of a 0.5% by mass aqueous solution of polyvinyl alcohol (Unitika Poval 050G, manufactured by Unitika Ltd.) (hereinafter referred to as PVA-1), and N,N-dimethylethanolamine equivalent to 1.2 times the total amount of carboxyl groups contained in the [polyester resin]. The mixture was stirred at 6,000 rpm in an open system using a tabletop homodisper (TK Robomix, manufactured by Tokushu Kika Kogyo Co., Ltd.). No precipitation of resin particles was observed at the bottom of the vessel, and the vessel was confirmed to be completely suspended. This state was maintained, and after 10 minutes, hot water was passed through the jacket and heated. When the temperature inside the vessel reached 68°C, the mixture was stirred at 7,000 rpm. The temperature inside the vessel was maintained at 68-70°C and further stirred for 20 minutes, yielding a milky white, uniform aqueous dispersion. Next, cold water was run through the jacket, and the mixture was cooled to room temperature while stirring at 3,500 rpm, and then filtered using a stainless steel filter (635 mesh, plain weave) to obtain a [crystalline polyester resin particle dispersion] containing polyester resin particles with a volume average primary particle size of 55 nm. Note that almost no resin particles remained on the filter during the filtration process.

(Production Example 14)
<Production of Aqueous Dispersion of Resin Fine Particles (B')>
The following materials were added to a reaction vessel equipped with a stirrer and a thermometer, and the mixture was stirred at 400 rpm for 15 minutes.
-material-
Water 683 parts by mass Sodium salt of methacrylic acid ethylene oxide adduct sulfate (Eleminol RS-30, manufactured by Sanyo Chemical Industries, Ltd.) 11 parts by mass Styrene 138 parts by mass Methacrylic acid 138 parts by mass Ammonium persulfate 1 part by mass The obtained emulsion was heated to raise the system temperature to 75°C and reacted for 5 hours.
Further, 30 parts by mass of a 1% by mass aqueous solution of ammonium persulfate was added, and the mixture was aged at 75°C for 5 hours to obtain an aqueous dispersion of resin fine particles (B') (vinyl resin: copolymer of styrene-methacrylic acid-methacrylic acid ethylene oxide adduct sulfate sodium salt).
The volume average primary particle diameter of the aqueous dispersion of resin fine particles (B') was measured in the same manner as in Production Example 4 and was found to be 140 nm.

Example 1
<Preparation of Masterbatch (MB)>
The following materials were added to a container and mixed using a Henschel mixer (manufactured by Nippon Coke and Engineering Co., Ltd.).
-material-
Water 1200 parts by mass Carbon black (Printex 35, DBP oil absorption = 42 mL/100 mg, pH = 9.5, manufactured by Evonik Dexa) 540 parts by mass Amorphous polyester resin 1200 parts by mass The mixture was kneaded using two rolls at 150°C for 30 minutes, then rolled and cooled, and pulverized using a pulverizer to obtain a masterbatch.

<Preparation of wax dispersion>
A container equipped with a stirring rod and a thermometer was charged with 50 parts by mass of paraffin wax (manufactured by Nippon Seiro Co., Ltd., HNP-9, hydrocarbon wax, melting point 75°C, SP value 8.8) as a release agent and 450 parts by mass of ethyl acetate. The mixture was heated to 80°C under stirring, maintained at 80°C for 5 hours, and then cooled to 30°C over 1 hour. A bead mill (Ultraviscomill, manufactured by Imex Co., Ltd.) was used to disperse the mixture under the conditions of a liquid feed rate of 1 kg/hr, a disk peripheral speed of 6 m/sec, 80% by volume of zirconia beads with a diameter of 0.5 mm, and 3 passes to obtain a wax dispersion.

<Preparation of Crystalline Polyester Resin Dispersion>
A vessel equipped with a stirring rod and a thermometer was charged with 50 parts by mass of the crystalline polyester resin of Production Example 2 and 450 parts by mass of ethyl acetate, and the mixture was heated to 80°C with stirring. The temperature was maintained at 80°C for 5 hours, and then cooled to 30°C over 1 hour. Dispersion was carried out using a bead mill (Ultraviscomill, manufactured by Imex) under conditions of a liquid feed rate of 1 kg/hr, a disk peripheral speed of 6 m/sec, a filling rate of 80% by volume of zirconia beads with 0.5 mm diameter, and 3 passes to obtain a [crystalline polyester resin dispersion].

<Preparation of oil phase>
Into another container equipped with a thermometer and a stirrer, 78 parts by mass of amorphous polyester resin, 70 parts by mass of crystalline polyester resin dispersion, 25 parts by mass of wax dispersion, and 16 parts by mass of masterbatch were placed, and ethyl acetate was added to a solid content concentration of 30% by mass, followed by stirring to dissolve thoroughly. Next, the mixture was stirred at 8,000 rpm using a TK homomixer (manufactured by Primix Corporation) to dissolve and disperse uniformly.
Furthermore, isophoronediamine (IPDA) was added in an amount such that the molar ratio (NH2/NCO) of the amino groups of IPDA to the isocyanate groups of the [intermediate polyester] was 0.98, and the mixture was stirred for 15 seconds at 8,000 rpm using a TK homomixer. Next, 30 parts by mass of the [intermediate polyester] prepared in a 50% by mass ethyl acetate solution was added, and the mixture was stirred for 30 seconds at 8,000 rpm using a TK homomixer to obtain [Oil phase 1].

<Preparation of aqueous phase>
In a container equipped with a stirrer and a thermometer, 75 parts by mass of ion-exchanged water, 1 part by mass of sodium carboxymethyl cellulose, 16 parts by mass of a 48.5% by mass aqueous solution of sodium dodecyl diphenyl ether disulfonate (Eleminol MON-7, manufactured by Sanyo Chemical Industries, Ltd.), and 5 parts by mass of ethyl acetate were mixed and stirred, and an amount equivalent to 1.6 parts by mass of the solids content of [aqueous dispersion (W0-1) of resin fine particles (A-1)] and an amount equivalent to 0.8 parts by mass of the solids content of [aqueous dispersion (W-1) of resin fine particles (B-1)] were further added to prepare an aqueous phase solution. This was designated [aqueous phase 1].

<Emulsification and desolvation>
50 parts by mass of [Aqueous Phase 1] was added to a container containing 29 parts by mass of [Oil Phase 1], and the mixture was mixed and stirred for 2 minutes at 8,000 rpm using a TK Homomixer, and then mixed for 20 minutes to obtain [Emulsified Slurry 1].
Next, [Emulsified Slurry 1] was placed in a container equipped with a stirrer and a thermometer, and the solvent was removed at 30°C for 8 hours, followed by aging at 45°C for 4 hours to obtain [Dispersed Slurry 1].

<Washing and drying>
100 parts by mass of the obtained [Dispersion Slurry 1] was filtered under reduced pressure to obtain a [filter cake], and then the following operations were carried out.
(1): 100 parts by mass of ion-exchanged water was added to the filter cake, and the mixture was mixed with a TK homomixer (at 12,000 rpm for 10 minutes), followed by filtration.
(2): 100 parts by mass of a 10% by mass aqueous solution of sodium hydroxide was added to the filter cake obtained in (1), and the mixture was mixed with a TK homomixer (at 12,000 rpm for 30 minutes), followed by filtration under reduced pressure.
(3): 100 parts by mass of 10% by mass hydrochloric acid was added to the filter cake obtained in (2), and the mixture was mixed with a TK homomixer (at 12,000 rpm for 10 minutes) and then filtered.
(4): 300 parts by mass of ion-exchanged water was added to the filter cake obtained in (3), and the mixture was mixed with a TK homomixer (at 12,000 rpm for 10 minutes) and then filtered.
The above steps (1) to (4) were repeated twice to obtain a washed filter cake.
The obtained [filter cake after washing treatment] was dried in a circulating air dryer at 45° C. for 48 hours, and sieved through a mesh with 75 μm openings to obtain [toner base particles 1].

<External Addition Treatment>
100 parts by mass of the obtained [toner base particles 1] was mixed with 1.0 part by weight of colloidal silica (Aerosil R972, manufactured by Nippon Aerosil) as an external additive in a sample mill to obtain [toner 1] after external addition treatment.

Example 2
[Toner base particles 2] were obtained in the same manner as in Example 1, except that in <Preparation of aqueous phase> of Example 1, an amount equivalent to 1.6 parts by mass of the solid content of [aqueous dispersion (W0-1) of resin fine particles (A-1)] and an amount equivalent to 0.8 parts by mass of the solid content of [aqueous dispersion (W-1) of resin fine particles (B-1)] were changed to an amount equivalent to 1.9 parts by mass of the solid content of [aqueous dispersion (W0-1) of resin fine particles (A-1)] and an amount equivalent to 0.5 parts by mass of the solid content of [aqueous dispersion (W-1) of resin fine particles (B-1)]. [Toner 2] was produced in the same manner as in Example 1 using the obtained [toner base particles 2].

Example 3
[Toner base particles 3] were obtained in the same manner as in Example 1, except that in <Preparation of aqueous phase> of Example 1, the amount equivalent to 1.6 parts by mass of the solid content of [Aqueous dispersion (W0-1) of resin fine particles (A-1)] and the amount equivalent to 0.8 parts by mass of the solid content of [Aqueous dispersion (W-1) of resin fine particles (B-1)] were changed to an amount equivalent to 2.4 parts by mass of the solid content of [Aqueous dispersion (W-7) of resin fine particles (B-7)]. [Toner base particles 3] was produced in the same manner as in Example 1 using the obtained [Toner base particles 3].

Example 4
[Toner base particles 4] were obtained in the same manner as in Example 1, except that in <Preparation of aqueous phase> of Example 1, the amount equivalent to 1.6 parts by mass of the solid content of [aqueous dispersion (W0-1) of resin fine particles (A-1)] and the amount equivalent to 0.8 parts by mass of the solid content of [aqueous dispersion (W-1) of resin fine particles (B-1)] were changed to an amount equivalent to 2.4 parts by mass of the solid content of [aqueous dispersion (W-8) of resin fine particles (B-8)]. [Toner base particles 4] was produced in the same manner as in Example 1 using the obtained [toner base particles 4].

Example 5
[Toner base particles 5] were obtained in the same manner as in Example 1, except that in <Preparation of aqueous phase> of Example 1, the amount equivalent to 1.6 parts by mass of the solid content of [aqueous dispersion (W0-1) of resin fine particles (A-1)] and the amount equivalent to 0.8 parts by mass of the solid content of [aqueous dispersion (W-1) of resin fine particles (B-1)] were changed to an amount equivalent to 2.4 parts by mass of the solid content of [aqueous dispersion (W-9) of resin fine particles (B-9)]. [Toner base particles 5] was produced in the same manner as in Example 1 using the obtained [toner base particles 5].

Example 6
[Toner base particles 6] were obtained in the same manner as in Example 1, except that in <Preparation of aqueous phase> of Example 1, the amounts equivalent to 1.6 parts by mass of the solid content of [aqueous dispersion (W0-1) of resin fine particles (A-1)] and 0.8 parts by mass of the solid content of [aqueous dispersion (W-1) of resin fine particles (B-1)] were changed to amounts equivalent to 1.6 parts by mass of the solid content of [aqueous dispersion (W0-2) of resin fine particles (A-2)] and 0.8 parts by mass of the solid content of [aqueous dispersion (W-4) of resin fine particles (B-4)]. [Toner base particles 6] was produced in the same manner as in Example 1 using the obtained [toner base particles 6].

Example 7
[Toner base particles 7] were obtained in the same manner as in Example 1, except that in <Preparation of aqueous phase> of Example 1, the amount equivalent to 1.6 parts by mass of the solid content of [aqueous dispersion of resin fine particles (A-1) (W0-1)] and the amount equivalent to 0.8 parts by mass of the solid content of [aqueous dispersion of resin fine particles (B-1) (W-1)] were changed to the amount equivalent to 2.4 parts by mass of the solid content of [crystalline polyester resin fine particle dispersion].
Using the obtained [toner base particles 7], [toner 7] was produced in the same manner as in Example 1.

(Example 8)
[Toner base particles 8] were obtained in the same manner as in Example 1, except that in <Preparation of aqueous phase> of Example 1, the amount equivalent to 1.6 parts by mass of the solid content of [aqueous dispersion of resin fine particles (A-1) (W0-1)] and the amount equivalent to 0.8 parts by mass of the solid content of [aqueous dispersion of resin fine particles (B-1) (W-1)] were changed to the amount equivalent to 2.4 parts by mass of the solid content of [aqueous dispersion of resin fine particles (B')].
Using the obtained [toner base particles 8], [toner 8] was produced in the same manner as in Example 1.

(Comparative Example 1)
Toner base particles 9 were obtained in the same manner as in Example 1, except that in the <Preparation of aqueous phase> of Example 1, the amount equivalent to 1.6 parts by mass of the solid content of [aqueous dispersion (W0-1) of resin fine particles (A-1)] and the amount equivalent to 0.8 parts by mass of the solid content of [aqueous dispersion (W-1) of resin fine particles (B-1)] were changed to an amount equivalent to 2.4 parts by mass of the solid content of [aqueous dispersion (W-5) of resin fine particles (B-5)].
Using the obtained [Toner base particles 9], [Toner 9] was produced in the same manner as in Example 1.

(Comparative Example 2)
Toner base particles 10 were obtained in the same manner as in Example 1, except that in the <Preparation of aqueous phase> of Example 1, the amount equivalent to 1.6 parts by mass of the solid content of [aqueous dispersion (W0-1) of resin fine particles (A-1)] and the amount equivalent to 0.8 parts by mass of the solid content of [aqueous dispersion (W-1) of resin fine particles (B-1)] were changed to the amount equivalent to 2.4 parts by mass of the solid content of [aqueous dispersion (W-6) of resin fine particles (B-6)].
Using the obtained [toner base particles 10], [toner 10] was produced in the same manner as in Example 1.

(Comparative Example 3)
Toner base particles 11 were obtained in the same manner as in Example 1, except that in the <Preparation of aqueous phase> of Example 1, the amounts corresponding to 1.6 parts by mass of the solid content of [aqueous dispersion (W0-1) of resin fine particles (A-1)] and 0.8 parts by mass of the solid content of [aqueous dispersion (W-1) of resin fine particles (B-1)] were changed to amounts corresponding to 1.9 parts by mass of the solid content of [aqueous dispersion (W0-1) of resin fine particles (A-1)] and 0.5 parts by mass of the solid content of [aqueous dispersion (W-2) of resin fine particles (B-2)].
Using the obtained [toner base particles 11], [toner 11] was produced in the same manner as in Example 1.

(Comparative Example 4)
Toner base particles 12 were obtained in the same manner as in Example 1, except that in the <Preparation of aqueous phase> of Example 1, the amounts corresponding to 1.6 parts by mass of the solid content of [aqueous dispersion (W0-1) of resin fine particles (A-1)] and 0.8 parts by mass of the solid content of [aqueous dispersion (W-1) of resin fine particles (B-1)] were changed to amounts corresponding to 1.9 parts by mass of the solid content of [aqueous dispersion (W0-1) of resin fine particles (A-1)] and 0.5 parts by mass of the solid content of [aqueous dispersion (W-3) of resin fine particles (B-3)].
Using the obtained [toner base particles 12], [toner 12] was produced in the same manner as in Example 1.

<Preparation of carrier>
To 100 parts by mass of toluene, 100 parts by mass of silicone resin (organostraight silicone), 5 parts by mass of γ-(2-aminoethyl)aminopropyltrimethoxysilane, and 10 parts by mass of carbon black were added, and the mixture was dispersed for 20 minutes using a homomixer to prepare a resin layer coating liquid.
Using a fluidized bed coating device, the resin layer coating liquid was applied to the surface of 1,000 parts by mass of spherical magnetite having a volume average particle size of 50 μm, to prepare a carrier.

<Preparation of Developer>
Using a ball mill, 5 parts by weight of each toner and 95 parts by weight of carrier were mixed to prepare each developer.

Next, the properties of each of the resulting toners and developers were evaluated as follows. The results are shown in Tables 1 to 3.

<Evaluation of Granulation Properties>
Each [toner] was dispersed in water, and the volume average primary particle size and particle size distribution (volume average primary particle size/number average particle size) were measured using a Coulter Counter "Multisizer III" (manufactured by Beckman Coulter, Inc.), and the granulation properties were evaluated according to the following criteria. Note that it is considered preferable that the granulation properties be such that when the volume average primary particle size of the toner is 5.0 μm to 5.9 μm, the particle size distribution is 1.20 or less.
[Evaluation criteria for granulation properties]
○: Particle size distribution is 1.20 or less ×: Particle size distribution is 1.21 or more

<Evaluation of low-temperature fixability>
Toner (powder form) was evenly placed on the surface of paper (Ricoh Company, Ltd., Type 6200, A4 size) to give a density of 0.8 mg/ ^cm2 , and the paper was passed through a pressure roller at a fixing speed (heating roller peripheral speed) of 213 mm/sec and a fixing pressure (pressure roller pressure) of 10 kg/ ^cm2 , and the temperature at which cold offset occurred (MFT) was measured. Note that a lower temperature at which cold offset occurred means better low-temperature fixability.
The toner (powder form) is applied to the paper surface using a printer without a thermal fixing device. There are no particular limitations on the method, and other methods may be used as long as the toner (powder form) can be applied uniformly to the paper surface at the above weight density.
[Evaluation Criteria for Low-Temperature Fixability]
◎: The minimum fixing temperature is 130°C or less. ○: The minimum fixing temperature is greater than 130°C and less than or equal to 135°C. △: The minimum fixing temperature is greater than 135°C and less than or equal to 140°C. ×: The minimum fixing temperature is greater than 140°C.

<Evaluation of Toner Adhesion>
The inter-particle force (Fp) of each toner when compressed to 160 kN/m ² can be measured using an Agrobot (manufactured by Hosokawa Micron Corporation), a powder layer compression/tensile property measuring device.
The inter-particle force (Fp) is calculated from the maximum tensile breaking force when the powder layer is broken by filling a certain amount of each toner into a cylindrical cell divided into upper and lower halves under the following conditions, holding each toner under a pressure of 160 kN/ ^m2 , and then lifting the upper cell, the powder layer height at the time of compression, the cell inner diameter, the toner average particle size, the toner true density, and the toner amount.
Specifically, measurements were carried out under the conditions shown below, and the inter-particle force (Fp) calculated using the attached application software was evaluated based on the inter-particle force (Fp) when the toner was compressed to 160 kN/ ^m² , according to the following criteria: The measurements were carried out after conditioning the toner at 23°C and 53% RH for 24 hours.
-Measurement conditions-
Toner amount: 8.00g±0.02g
・Environmental temperature: 25±2℃
・Humidity: 30±5%RH
Cell inner diameter: 25 mm
Cell temperature: 25°C
Spring wire diameter: 1.0 mm
Compression speed: 0.1 mm/sec
Compression load: 8 kg (pressure: 160 kN/m2)
Compression hold time: 60 seconds
Pulling speed: 0.6 mm/sec
Tensile sampling start time: 0 sec
Tensile sampling time: 25 seconds
[Evaluation Criteria for Toner Adhesion]
◎: Best Fp≦200
〇: Good 200<Fp≦300
△: Acceptable 300<Fp≦500
×: NG Breaking failure

<Evaluation of filming resistance>
Each developer was placed in an image forming apparatus (RICOH MPC 6003, manufactured by Ricoh Company, Ltd.), and a solid image with a deposition amount of 0.4 mg/ ^cm2 was output on paper (Ricoh Company, Ltd., Type 6200, A4 size) through exposure, development, and transfer processes. A continuous paper feed test of 2,000 sheets was conducted, and the contamination of the latent image carrier and the contamination state of the charging device were visually observed and evaluated according to the following criteria.
[Evaluation criteria for filming resistance]
◎: No contamination on the latent image carrier and no filming on the charging device ○: Slight contamination on the latent image carrier and slight filming on the charging device △: Slight contamination on the latent image carrier and slight filming on the charging device, and abnormal images occur over time ×: Slight contamination on the latent image carrier and slight filming on the charging device, and abnormal images occur early

<Overall Judgment>
Based on the results of each evaluation item, a judgment will be made according to the following criteria.
[Evaluation criteria]
◎: Three or more evaluation items are "◎"
〇: There are two or less "◎" marks among the evaluation items, and no "△" or "×" marks. △: One of the evaluation items is "△".
×: Any of the evaluation items is "×"

From the results in Tables 1 to 3, it is clear that Examples 1 to 8 of the present invention exhibit excellent performance in all of granulation property, low-temperature fixability, adhesive strength, and filming resistance.
In Comparative Example 1, the amount of aggregates on the surface of the toner matrix was large, resulting in a slight decrease in low-temperature fixability, and the amount of liberated external additive could not be optimized due to the excessive amount of aggregates, resulting in poor filming resistance.
In Comparative Example 2, the amount of aggregates on the surface of the toner matrix is small, and the spacer effect is weak, resulting in poor adhesive strength.
Comparative Example 3 has a larger standard deviation than Comparative Example 1, and similarly Comparative Example 4 has a larger standard deviation than Comparative Example 2. Therefore, the toner base particles are exposed unevenly, resulting in a deterioration in adhesion.

The present invention includes, for example, the following aspects.
<1> A toner having a plurality of resin microparticles on the surface of a toner base particle as observed by a scanning electron microscope (SEM), the toner comprising at least a resin and a wax, wherein when the resin microparticles having a major axis of 3R or more are aggregated, where R is the major axis of the smallest particle among the resin microparticles, the proportion of the aggregates occupying the surface of the toner base particle is 15% or more and 60% or less.
<2> The toner according to <1>, wherein the resin particles have a core resin and a shell resin that coats at least a part of the surface of the core resin.
<3> The toner according to <2>, wherein the shell resin contains a styrene-acrylic resin.
<4> The toner according to any one of <1> to <3>, wherein the ratio of the aggregates to the surface of the toner base particles is 15% or more and 35% or less.
<5> The toner according to any one of <1> to <4>, wherein the standard deviation of the distance between adjacent resin fine particles that are not in contact with each other and are present on the surface of the toner base particle is 500 nm or less.
<6> The toner according to any one of <1> to <5>, wherein the resin fine particles have a volume average primary particle size of 10 nm or more and 100 nm or less.
<7> A toner storage unit containing the toner according to any one of <1> to <6>.
<8> An image forming apparatus comprising the toner storage unit according to <7>.
<9> An image forming method including: an electrostatic latent image forming step of forming an electrostatic latent image on an electrostatic latent image carrier; and a developing step of forming a toner image, which is a visible image, by developing the electrostatic latent image formed on the electrostatic latent image carrier with a toner, wherein the toner is the toner according to any one of <1> to <6>.
<10> A method for producing the toner according to any one of <1> to <6>, comprising: a composite particle forming step of forming composite particles by adhering resin fine particles to the surfaces of toner base particles; and a removal step of removing at least a portion of the resin fine particles from the composite particles.
<11> The method for producing a toner according to <10>, wherein the removing step is a step of washing with a basic aqueous solution.

The toner described in any one of <1> to <6>, the toner storage unit described in <7>, the image forming apparatus described in <8>, the image forming method described in <9>, and the toner manufacturing method described in any one of <10> to <11> can solve various problems that have existed in the past and achieve the object of the present invention.

REFERENCE SIGNS LIST 1 Shell resin 2 Core-shell resin 3 Resin particles 4 Toner base particles 101 Latent image carrier 102 Charging device 103 Exposure from exposure device 104 Developing device 105 Recording paper 107 Cleaning unit 108 Transfer roller 160Y Sub-hopper (yellow)
160C Sub Hopper (Cyan)
160M Sub Hopper (Magenta)
160K Sub Hopper (Black)
180Y Image forming unit (yellow)
180C Image forming unit (cyan)
180M Image forming unit (magenta)
180K Image Forming Unit (Black)
210 Paper feed unit 211 Paper feed cassette 212 Paper feed roller 220 Conveying unit 221 Roller 222 Timing roller 223 Paper discharge roller 224 Paper discharge tray 230 Imaging unit 231Y Photosensitive drum (yellow)
231C Photosensitive drum (cyan)
231M Photosensitive drum (magenta)
231K Photosensitive Drum (Black)
232Y Charger (Yellow)
232C Charger (cyan)
232M Charger (Magenta)
232K Charger (Black)
233 Exposure device 233a Light source 233bY Polygon mirror (yellow)
233bC Polygon Mirror (Cyan)
233bM Polygon Mirror (Magenta)
233bK Polygon Mirror (Black)
234Y Toner Bottle (Yellow)
234C Toner Bottle (Cyan)
234M Toner Bottle (Magenta)
234K Toner Bottle (Black)
236Y Cleaner (Yellow)
236C Cleaner (cyan)
236M Cleaner (Magenta)
236K Cleaner (Black)
240 Transfer unit 241 Drive roller 242 Driven roller 243 Intermediate transfer belt 244 Primary transfer roller 244Y Primary transfer roller (yellow)
244C Primary transfer roller (cyan)
244M Primary transfer roller (magenta)
244K Primary Transfer Roller (Black)
245 Secondary opposing roller 246 Secondary transfer roller 250 Fixing unit 251 Fixing belt 252 Pressure roller L Laser P Paper

Japanese Patent Application Laid-Open No. 2019-099809 Japanese Patent Application Laid-Open No. 2019-143128 JP 2013-011644 A JP 2009-098194 A JP 2014-178528 A

Claims (8)

A toner having a plurality of resin fine particles on the surface of a toner base particle containing a crystalline polyester resin , an amorphous polyester resin, and a wax, as observed by a scanning electron microscope (SEM),
The wax is a hydrocarbon wax or an ester wax,
the resin fine particles have a core resin and a shell resin that coats at least a part of the surface of the core resin,
the shell resin comprises a styrene-acrylic resin;
the volume average primary particle diameter of the resin fine particles is 10 nm or more and 100 nm or less;
A toner characterized in that, when the long diameter of the smallest particle among the resin fine particles is R and the resin fine particles having a long diameter of 3R or more are aggregated, the proportion of the aggregate occupying the surface of the toner base particle is 16% or more and 60% or less. 2. The toner according to claim 1 , wherein the proportion of the aggregates on the surface of the toner base particle is 16% or more and 35% or less. 3. The toner according to claim 1, wherein the standard deviation of the distance between adjacent resin particles that are not in contact with each other and are present on the surface of the toner base particle is 500 nm or less. A toner storage unit containing the toner according to any one of claims 1 to 3 . An image forming apparatus comprising the toner storage unit according to claim 4 . The method includes an electrostatic latent image forming step of forming an electrostatic latent image on an electrostatic latent image carrier, and a developing step of developing the electrostatic latent image formed on the electrostatic latent image carrier with toner to form a toner image, which is a visible image,
An image forming method, wherein the toner is the toner according to any one of claims 1 to 3 . A method for producing the toner according to any one of claims 1 to 3 , comprising the steps of:
a composite particle forming step of forming composite particles by adhering resin fine particles to the surfaces of toner base particles;
a removing step of removing at least a part of the resin fine particles from the composite particles. The method for producing a toner according to claim 7 , wherein the removing step is a step of washing with a basic aqueous solution.