JP7790910B2 - Toner and toner manufacturing method - Google Patents

Description

The present invention relates to toner used in electrophotographic image forming devices.

In recent years, there has been an increasing demand for energy-saving measures in electrophotographic image forming devices. As a measure to save energy, technology that fixes toner at low temperatures is being considered in order to reduce power consumption in the fixing process.

One way to improve the low-temperature fixability of a toner is to lower the glass transition point of the toner's resin component. However, lowering the glass transition point of the resin component leads to a decrease in the toner's heat-resistant storage stability, making it difficult to achieve both low-temperature fixability and heat-resistant storage stability with this method.

Therefore, in order to achieve both low-temperature fixability and heat-resistant storage stability in toner, methods of using crystalline resins in toner are being considered. Amorphous resins, which are commonly used as resin components in toner, do not show clear endothermic peaks in differential scanning calorimetry (DSC) measurements. On the other hand, crystalline resins do show endothermic peaks in DSC measurements. Due to the regular arrangement of alkyl groups between or within molecules, crystalline resins have the property of hardly softening up to the melting point. Due to this property, crystalline resins undergo a sharp melting of the crystals at the melting point, resulting in a sudden drop in viscosity.

For this reason, crystalline resins have attracted attention as materials that offer excellent sharp melting properties and combine low-temperature fixing properties and heat-resistant storage stability for toner. Crystalline vinyl resins are known as one type of crystalline resin. Crystalline vinyl resins are vinyl polymers that contain monomer units with long-chain alkyl groups. In other words, crystalline vinyl resins have a main chain skeleton and long-chain alkyl groups as side chains. The long-chain alkyl groups in the side chains are regularly arranged and crystallize, resulting in the resin exhibiting crystallinity.

Patent Document 1 proposes a toner that uses a crystalline vinyl resin containing a monomer unit with a long-chain alkyl group.

JP 2014-130243 A

As a result of the inventors' investigation of the toner described in Patent Document 1, they recognized that further improvements were needed in terms of toner durability. Specifically, they found that when a crystalline vinyl resin having a monomer unit with a long-chain alkyl group is used in combination with wax, the toner may be more susceptible to cracking and chipping.

One aspect of the present disclosure is to provide a toner that has excellent low-temperature fixability, heat-resistant storage stability, and releasability, as well as excellent durability.

According to one aspect of the present disclosure, there is provided a toner having toner particles containing a resin component and a wax,
the resin component is a vinyl polymer A having a monomer unit A represented by the following formula (A),
the wax is composed solely of esters of hexahydric alcohol and aliphatic monocarboxylic acid,
The wax contained in the toner particles includes a wax that forms a eutectic structure with the resin component and a single wax that does not form a eutectic structure,
When a backscattered electron image of the cross section of the toner particle is obtained by observing the cross section of the toner particle with a scanning transmission electron microscope, the brightness of each pixel constituting the backscattered electron image is divided into 256 gradations from a brightness of 0 at the darkest point to a brightness of 255 at the brightest point, and a brightness histogram is obtained in which the horizontal axis represents brightness and the vertical axis represents the number of pixels.
When the total number of pixels with brightness 0 to 9 is C and the total number of pixels with brightness 0 to 245 is A,
The C and the A satisfy the following formula (1),
0.002 ≦C/A≦0.250 (1)
The luminance indicating the maximum number P of pixels in the range of luminance 10 to luminance 245 of the histogram is defined as luminance X,
The luminance at which the number of pixels falls below 20% of P for the first time from the luminance X toward the luminance 245 is defined as luminance M,
When the number of pixels falls below 20% of P for the first time from the brightness X to the brightness 10, the brightness is defined as N.
A toner is provided which is characterized by a brightness M-brightness N value of 120 to 235.

(In formula (A), ^R1 represents H or _CH3 , and ^R2 represents an alkyl group having 18 to 36 carbon atoms.)

One aspect of the present disclosure provides a toner that has excellent low-temperature fixability, heat-resistant storage stability, and releasability, as well as excellent durability.

10 is an example of a 256-level brightness histogram obtained from a cross-sectional image of a toner particle of Toner 1 in an embodiment of the present disclosure. 10 is an example of a 256-level brightness histogram obtained from a cross-sectional image of a toner particle of toner 35 in an embodiment of the present disclosure.

When a numerical range is expressed as "xx or more and xx or less" or "xx to xx," it means that the numerical range includes the endpoints, which are the lower and upper limits, unless otherwise specified. When a numerical range is stated in stages, the upper and lower limits of each numerical range can be combined in any way.

(Meth)acrylate means acrylate and/or methacrylate, and (meth)acrylic acid means acrylic acid and/or methacrylic acid.

A monomer unit is a unit that makes up a polymer and refers to the reacted form of a monomer (polymerizable monomer). For example, one section of carbon-carbon bond in the main chain of a polymer formed by polymerizing a vinyl monomer is one monomer unit. A vinyl monomer can be represented by the following formula (Z), and a vinyl monomer unit is a structural unit of a polymer and is the reacted form of a monomer represented by the following formula (Z). A monomer unit may also be simply referred to as a "unit."

(In formula (Z), _R represents a hydrogen atom or an alkyl group, and _R represents an optional substituent.)

A crystalline resin is a resin that shows a clear endothermic peak in differential scanning calorimetry (DSC) measurements using the resin, toner particles, or toner as the measurement sample (differential scanning calorimetry measurements are also referred to as DSC measurements).

A eutectic state refers to a state in which microcrystals of two or more substances are mixed together and crystallized.

<Background to the invention and the mechanism by which the effects of the present disclosure are realized>
The present inventors believe that the reason why the durability of the toner disclosed in Patent Document 1 needs to be further improved is as follows.

Toners containing a polymer with a monomer unit having a long-chain alkyl group as the resin component of the toner tend to exhibit excellent low-temperature fixability and heat-resistant storage stability. The inventors believe this is because the polymer has long-chain alkyl groups in its side chains, which tend to arrange themselves regularly, thereby increasing crystallinity. This is an advantageous characteristic in terms of reducing the amount of heat required in the fixing step in the electrophotographic image formation process.

However, it was discovered that when wax is added to the above toner to improve release properties, the durability of the toner may become insufficient. Specifically, it was discovered that the toner may be prone to cracking and chipping. One possible reason for this is that the resin component and wax in the toner particles may be prone to crystallizing independently, making it easy for wax domains with clear boundaries to form relative to the resin component.

When the brightness histogram of the cross section of the above toner particles was examined, a low-brightness peak corresponding to the wax and a high-brightness peak corresponding to the crystalline vinyl resin containing a monomer unit with a long-chain alkyl group were observed separately. An example of this brightness histogram is shown in Figure 2. This shows that the resin component and wax each have a clear boundary and are contained in the toner particles in an independent state.

The inventors therefore came up with the idea of forming a eutectic between the wax and the resin component, thereby making it difficult for the peak corresponding to the resin component and the peak corresponding to the wax to become independent, and controlling the peak corresponding to the resin component to become broad in the brightness histogram of the cross section of the toner particle. This makes it difficult for the resin component and the wax to form a clear boundary, without impairing the releasability provided by the wax, and the inventors believed that this would make it easier to obtain a toner with excellent durability.

Based on the above considerations, the inventors conducted further research and found that a toner having the above constituent elements can have excellent low-temperature fixing properties, heat-resistant storage stability, and releasability, and is likely to be a toner that can also have excellent durability. Each of the constituent elements is described in detail below.

<Brightness histogram of a toner particle cross section>
When the brightness histogram according to the present disclosure was obtained by scanning transmission electron microscope observation,
The luminance indicating the maximum number P of pixels in the range of luminance 10 to luminance 245 of the histogram is defined as luminance X,
The luminance at which the number of pixels falls below 20% of P for the first time from the luminance X toward the luminance 245 is defined as luminance M,
When the number of pixels falls below 20% of P for the first time from the brightness X to the brightness 10, the brightness is defined as N.
The toner is characterized in that the value of luminance M-luminance N is 120 to 235.

Under the conditions for obtaining a cross-sectional image of a toner particle, described below, the areas where wax is present appear dark in a dark-field image of the cross section of the toner particle, while the areas where resin components are present appear relatively bright. The brightness of each pixel constituting the cross-sectional image of the toner particle is divided into 256 gradations, ranging from 0 to 255, to obtain a brightness histogram with brightness on the horizontal axis and pixel count on the vertical axis. With the darkest area being 0 and the brightest area being 255, the brightness X is the brightness that indicates the maximum number of pixels (P) within the brightness range of 10 to 245 in the brightness histogram. The brightness X that indicates the maximum number of pixels within the above range is the brightness at which the number of pixels is greatest among the brightnesses corresponding to the area primarily composed of resin components contained in the toner. Furthermore, as described below, when obtaining the brightness histogram in this disclosure, an image obtained by setting brightness X to 150 was used. In other words, it is preferable to obtain the brightness histogram by setting the brightness at 150, which indicates the maximum number of pixels among the brightnesses corresponding to the area primarily composed of resin components. Which luminance in the luminance histogram corresponds to the portion where the resin component is the main component can be determined by observing the luminance histogram in relation to the cross-sectional image of the toner particle. This is because, generally, the portion occupying the largest area in the cross-sectional image of the toner particle corresponds to the resin component.

In addition, pixels with a brightness of 246 or higher are excluded because they may contain noise such as blown-out highlights.

In the brightness histogram above, lower brightness values are darker and higher brightness values are brighter, so pixels with a brightness of 0 to 9 correspond to pure wax. Furthermore, pixels with a brightness of 10 to 245 correspond to resin components and eutectic structures of wax and resin components. In this disclosure, pure wax refers to wax that has a clear boundary with the resin component.

Furthermore, the luminance when the number of pixels falls below 20% of P for the first time as the number of pixels increases from luminance X to luminance 245 is defined as luminance M,
When the number of pixels falls below 20% of P for the first time from brightness X to brightness 10, the brightness is defined as brightness N.
The value of luminance M-luminance N is 120-235.

The value of brightness M - brightness N indicates how broad the peak is, with the maximum value at pixel number P at brightness X. The larger this value, the more the toner particles contain a eutectic structure of wax and resin components. The inclusion of this eutectic structure in the toner particles reduces the likelihood of a clear boundary between the resin components and wax, without impairing the toner's releasability, making it easier to obtain a toner with excellent durability.

In other words, when the value of brightness M - brightness N is 120 or higher, it is easier to obtain a toner with excellent releasability and durability. Therefore, it is 120 or higher, and preferably 150 or higher. There is no particular upper limit, but it is 235 or lower, more preferably 200 or lower, and even more preferably 180 or lower.

If the value of luminance M - luminance N is 119 or less, the releasability or durability may be insufficient. Here, the reason why the value of luminance M - luminance N becomes small is considered to be the following (1) and/or (2).
(1) In the toner particles, the wax is completely dissolved in the resin component.
(2) In the toner particles, the wax is contained in the resin component with a clear boundary.

In (1) above, a sharp peak corresponding to the state in which the wax and resin components are compatible is observed in the brightness histogram. Because the wax and resin components are compatible, there are fewer starting points for cracking and chipping in the toner, which is thought to be advantageous for durability. However, because the wax is compatible with the resin components, the wax is less likely to seep onto the toner surface during fixing, which is thought to reduce releasability.

As mentioned above, in (2) above, the toner is prone to cracking and chipping, and the durability of the toner is likely to decrease.

Methods for controlling the luminance M - luminance N value within the above range include controlling the type and amount of wax added, or performing heat treatment to create a eutectic between the wax and resin components.

The above-mentioned heat treatment involves first raising the temperature to a point where both the wax and resin components are in a molten state, and then maintaining the temperature at which the wax preferentially crystallizes. In other words, the temperature is maintained below the melting point of the wax but above the melting point of the resin component. This allows the wax and resin components to crystallize under conditions favorable to the wax from a mixed state, which is thought to make it easier for the eutectic structure to be incorporated into the toner particles.

Furthermore, even without the heat treatment, it was found that the luminance M - luminance N value can fall within the preferred range when a large amount of an ester wax with multiple long-chain alkyl groups and a branched structure, such as dipentaerythritol hexabehenate, is used.

In the above brightness histogram, when the total number of pixels in the brightness range of 0 to 9 is C and the total number of pixels in the brightness range of 0 to 245 is A, C and A satisfy the following formula (1).
0.000≦C/A≦0.250 (1)

As described above, in the brightness histogram, the total number of pixels in the brightness range of 0 to 9 corresponds to the single wax. Satisfying the above formula (1), i.e., the smaller the amount of single wax in the toner particles, the fewer the starting points for cracking and chipping of the toner, making it easier to obtain a toner with excellent durability. Preferably, the following formula (2) is satisfied, more preferably the following formula (3) is satisfied, and even more preferably the following formula (4) is satisfied.
0.000≦C/A≦0.100 (2)
0.000≦C/A≦0.080 (3)
0.000≦C/A≦0.040 (4)

<Resin component>
The resin component is preferably a binder resin. That is, the toner has toner particles containing a binder resin and a wax, and the binder resin preferably contains a vinyl polymer A having a monomer unit A represented by the above formula (A).

<Vinyl Polymer A and Monomer Unit A>
The vinyl polymer A has a monomer unit A represented by the following formula (A).

(In formula (A), ^R1 represents H or _CH3 , and ^R2 represents an alkyl group having 18 to 36 carbon atoms.)

When the monomer unit A contained in the vinyl polymer A has a long-chain alkyl group (an alkyl group having 18 to 36 carbon atoms) as a side chain of the vinyl polymer A, the crystallinity of the vinyl polymer A is likely to be enhanced, making it easier to obtain a toner with excellent low-temperature fixing properties and heat-resistant storage stability. Furthermore, the vinyl polymer A is preferably a crystalline resin that shows a clear endothermic peak in DSC measurement.

Monomer unit A can be incorporated as a monomer unit into vinyl polymer A by vinyl polymerization of a (meth)acrylic acid ester having an alkyl group with 18 to 36 carbon atoms as a polymerizable monomer.

Examples of (meth)acrylic acid esters having an alkyl group having 18 to 36 carbon atoms include (meth)acrylic acid esters having a linear alkyl group having 18 to 36 carbon atoms [stearyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, heneicosanyl (meth)acrylate, behenyl (meth)acrylate, lignoceryl (meth)acrylate, ceryl (meth)acrylate, octacosyl (meth)acrylate, myricyl (meth)acrylate, dodriaconta (meth)acrylate, etc.] and (meth)acrylic acid esters having a branched alkyl group having 18 to 36 carbon atoms [2-decyltetradecyl (meth)acrylate, etc.].

Of these, from the viewpoint of low-temperature fixability and heat-resistant storage stability of the toner, preferred are (meth)acrylic acid esters having a linear alkyl group of 18 to 36 carbon atoms, more preferred are (meth)acrylic acid esters having a linear alkyl group of 18 to 30 carbon atoms, and even more preferred are linear stearyl (meth)acrylate and behenyl (meth)acrylate. That is, in the above formula (A), ^R2 is a linear alkyl group of 18 to 36 carbon atoms, more preferably a linear alkyl group of 18 to 30 carbon atoms, and even more preferably an alkyl group of 18 or 22 carbon atoms. Also, ^R1 is preferably hydrogen.

The polymerizable monomer (hereinafter also referred to as monomer (a)) that forms monomer unit A and monomer unit A may be used alone or in combination of two or more types.

It is also preferable that the content of monomer unit A in vinyl polymer A is 20.0 to 80.0% by mass. If this content is 20.0% by mass or more, a toner with excellent low-temperature fixability and heat-resistant storage stability is easily obtained. Therefore, it is preferably 20.0% by mass or more, more preferably 40.0% by mass or more, and more preferably 45.0% by mass or more. Furthermore, if this content is 80.0% by mass or less, a toner with appropriate elasticity is easily obtained. Therefore, it is preferably 80.0% by mass or less, more preferably 75.0% by mass or less, and even more preferably 60.0% by mass or less.

The content of monomer unit A is the sum of the content of all monomer units represented by the above formula (A). The same applies when multiple monomers (a) are present.

It is also preferable that the content of vinyl polymer A in the resin component is 30.0% by mass or more. When this content is 30.0% by mass or more, a toner with excellent low-temperature fixability and heat-resistant storage stability is easily obtained. Therefore, it is preferably 30.0% by mass or more, more preferably 40.0% by mass or more, even more preferably 60.0% by mass or more, and even more preferably 80.0% by mass or more. Even more preferably, the content is 100.0% by mass, i.e., the resin component is made up solely of vinyl polymer A. There is no particular upper limit, but it is 100.0% by mass.

The weight-average molecular weight (Mw) of vinyl polymer A is preferably 10,000 to 200,000. It is more preferable that the Mw be 20,000 or more and 150,000 or less, and even more preferable that it be 40,000 to 70,000. Having an Mw within the above range is preferable because it makes it easier to appropriately control the elasticity of the toner.

In addition, from the viewpoint of low-temperature fixability, the melting point of vinyl polymer A is preferably 50 to 80°C.

<Other Monomer Units>
From the viewpoint of appropriately controlling the physical properties of the toner, the vinyl polymer A preferably contains a monomer unit other than the monomer unit A described above.

Vinyl polymer A having other monomer units can be incorporated as monomer units of vinyl polymer A by vinyl polymerization of the corresponding polymerizable monomer (hereinafter also referred to as "other monomer").

Examples of the other monomers include the following monomers, and one type may be used alone, or two or more types may be used in combination.
Monomers having a nitrile group; for example, acrylonitrile, methacrylonitrile, etc.
Monomers having a hydroxy group; for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, etc.
Monomers having an amide group: for example, acrylamide, and monomers obtained by reacting an amine having 1 to 30 carbon atoms with a carboxylic acid having 2 to 30 carbon atoms and an ethylenically unsaturated bond (acrylic acid, methacrylic acid, etc.).
Monomers having a urethane group: for example, alcohols having 2 to 22 carbon atoms and having an ethylenically unsaturated bond (e.g., 2-hydroxyethyl methacrylate, vinyl alcohol, etc.) and isocyanates having 1 to 30 carbon atoms [monoisocyanate compounds (e.g., benzenesulfonyl isocyanate, tosyl isocyanate, phenyl isocyanate, p-chlorophenyl isocyanate, butyl isocyanate, hexyl isocyanate, t-butyl isocyanate, cyclohexyl isocyanate, octyl isocyanate, 2-ethylhexyl isocyanate, dodecyl isocyanate, adamantyl isocyanate, 2,6-dimethylphenyl isocyanate, 3,5-dimethylphenyl isocyanate, and 2,6-dipropylphenyl isocyanate, etc.], aliphatic diisocyanates, Cyanate compounds (trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, etc.), alicyclic diisocyanate compounds (1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated tetramethylxylylene diisocyanate, etc.), and aromatic diisocyanates a monomer obtained by reacting a monomer with a diisocyanate such as a phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, xylylene diisocyanate, etc.), and an alcohol having 1 to 26 carbon atoms (methanol, ethanol, propanol, isopropyl alcohol, butanol, t-butyl alcohol, pentanol, heptanol, octanol, 2-ethylhexanol, nonanol, decanol, undecyl alcohol, lauryl alcohol, dodecyl alcohol, Monomers obtained by reacting an isocyanate having 2 to 30 carbon atoms and an ethylenically unsaturated bond (e.g., chol, myristyl alcohol, pentadecyl alcohol, cetanol, heptadecanol, stearyl alcohol, isostearyl alcohol, elaidyl alcohol, oleyl alcohol, linoleyl alcohol, linolenyl alcohol, nonadecyl alcohol, heneicosanol, behenyl alcohol, erucyl alcohol, etc.) with an isocyanate having 2 to 30 carbon atoms and an ethylenically unsaturated bond (e.g., 2-isocyanatoethyl (meth)acrylate, 2-(0-[1'-methylpropylideneamino]carboxyamino)ethyl (meth)acrylate, 2-[(3,5-dimethylpyrazolyl)carbonylamino]ethyl (meth)acrylate, 1,1-(bis(meth)acryloyloxymethyl)ethyl isocyanate, etc.).
Monomers having a urea group: for example, monomers obtained by reacting an amine having 3 to 22 carbon atoms [primary amines (normal butylamine, t-butylamine, propylamine, isopropylamine, etc.), secondary amines (di-normal ethylamine, di-normal propylamine, di-normal butylamine, etc.), aniline, cycloxylamine, etc.] with an isocyanate having 2 to 30 carbon atoms and an ethylenically unsaturated bond.
Vinyl esters: for example, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl pivalate, vinyl octylate. Monomers having a carboxy group: for example, methacrylic acid, acrylic acid, 2-carboxyethyl (meth)acrylate.
(Meth)acrylic acid esters: methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and the like.
Styrene-based monomers: styrene, α-methylstyrene, etc.

Among the above, monomers having a nitrile group are preferred. Using these makes it easier to control the melting point without excessively reducing the crystallinity of the vinyl polymer A, and makes it easier to obtain a toner with excellent low-temperature fixability and heat-resistant storage stability. Furthermore, using ethyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, or styrene is preferred because it makes it easier to appropriately control the elasticity of the toner.

<Resins other than vinyl polymer A>
In addition to the vinyl polymer A, materials that can be used as the resin component of the toner include vinyl resins, polyesters, polyurethanes, epoxy resins, etc. that do not fall under the category of the vinyl polymer A. Among these, vinyl resins, polyesters, and polyurethanes that do not fall under the category of the vinyl polymer A are preferred from the viewpoint of electrophotographic properties.

Monomers constituting vinyl resins that do not fall under the category of vinyl polymer A include the above-mentioned monomers other than monomer (a). Two or more types may be used in combination, if necessary.

Polyesters can be obtained by the condensation polymerization reaction of divalent or higher polycarboxylic acids and polyhydric alcohols.

Examples of polycarboxylic acids include the following compounds:

Dibasic acids such as succinic acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, malonic acid, and dodecenylsuccinic acid, and their anhydrides or lower alkyl esters, as well as aliphatic unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, and citraconic acid. 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, and their anhydrides or lower alkyl esters. These may be used alone or in combination of two or more.

Examples of polyhydric alcohols include the following compounds:

Alkylene glycols (ethylene glycol, 1,2-propylene glycol, and 1,3-propylene glycol); alkylene ether glycols (polyethylene glycol and polypropylene glycol); alicyclic diols (1,4-cyclohexanedimethanol); bisphenols (bisphenol A); and alkylene oxide (ethylene oxide and propylene oxide) adducts of alicyclic diols. The alkyl moieties of the alkylene glycols and alkylene ether glycols may be linear or branched. In the present disclosure, branched alkylene glycols are also preferably used. Further examples include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. These may be used alone or in combination of two or more.

In addition, monovalent acids such as acetic acid and benzoic acid, and monovalent alcohols such as cyclohexanol and benzyl alcohol can also be used as needed to adjust the acid value and hydroxyl value.

There are no particular limitations on the method for producing polyester, but examples include transesterification and direct polycondensation.

Polyurethane is obtained by reacting a diol component with a diisocyanate component.

Diisocyanate components include the following: aromatic diisocyanates with 6 to 20 carbon atoms (excluding carbon atoms in NCO groups, the same applies below); aliphatic diisocyanates with 2 to 18 carbon atoms; alicyclic diisocyanates with 4 to 15 carbon atoms; modified products of these diisocyanates (modified products containing urethane groups, carbodiimide groups, allophanate groups, urea groups, biuret groups, uretdione groups, uretoimine groups, isocyanurate groups, or oxazolidone groups; hereinafter also referred to as "modified diisocyanates"); and mixtures of two or more of these.

Aromatic diisocyanates include: m- and/or p-xylylene diisocyanate (XDI) and α,α,α',α'-tetramethylxylylene diisocyanate.

Also, examples of aliphatic diisocyanates include: ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), and dodecamethylene diisocyanate.

Also, examples of alicyclic diisocyanates include isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4'-diisocyanate, cyclohexylene diisocyanate, and methylcyclohexylene diisocyanate.

Among these, aromatic diisocyanates with 6 to 15 carbon atoms, aliphatic diisocyanates with 4 to 12 carbon atoms, and alicyclic diisocyanates with 4 to 15 carbon atoms are preferred, with XDI, IPDI, and HDI being particularly preferred.

In addition to the diisocyanate component, tri- or higher isocyanate compounds can also be used.

Diol components that can be used in polyurethanes include the same dihydric alcohols that can be used in the polyesters described above.

<Wax>
The wax contained in the toner particles is preferably an ester wax. One type of ester wax may be used alone, or two or more types may be used in combination.

In this disclosure, the ester wax has at least one ester bond per molecule, and either natural ester wax or synthetic ester wax may be used.

There are no particular limitations on ester waxes, but examples include the following:

Esters of monohydric alcohols and monocarboxylic acids, such as behenyl behenate, stearyl stearate, and palmityl palmitate;
Esters of dicarboxylic acids and monoalcohols, such as dibehenyl sebacate;
Esters of dihydric alcohols and monocarboxylic acids, such as ethylene glycol distearate and hexanediol dibehenate;
Esters of trihydric alcohols and monocarboxylic acids, such as glycerin tribehenate;
Esters of tetrahydric alcohols and monocarboxylic acids, such as pentaerythritol tetrastearate and pentaerythritol tetrapalmitate;
Esters of hexahydric alcohols and monocarboxylic acids, such as dipentaerythritol hexastearate, dipentaerythritol hexapalmitate, and dipentaerythritol hexabehenate;
Esters of polyfunctional alcohols and monocarboxylic acids, such as polyglycerin behenate; natural ester waxes, such as carnauba wax and rice wax;
The ester wax is preferably an ester of an alcohol and an aliphatic monocarboxylic acid, and preferably satisfies the following formula (5), where Ac is the number of carbon atoms in the linear alkyl group represented by ^R2 in the monomer unit A and Wc is the average number of carbon atoms in the linear alkyl groups contained in the ester wax:
|Ac-Wc|≦6.0... (5)
In the present disclosure, straight chain alkyl groups do not include alkylene or branched alkyl groups.

By satisfying the above formula (5), it is believed that the ester wax and vinyl polymer A are more likely to form a eutectic, making it easier to obtain a toner with excellent release properties and durability. The reason that the ester wax and vinyl polymer A are more likely to form a eutectic is that the lengths of the linear alkyl chains possessed by the vinyl polymer A and the wax are similar, making it easier to form a stable crystal structure not only when they are completely separated and crystallized independently, but also when they are entangled. The inventors believe that this makes it easier for the ester wax and vinyl polymer A to form a eutectic. More preferably, |Ac - Wc| ≦ 4.0, and even more preferably, |Ac - Wc| ≦ 2.0.

When there are multiple types of linear alkyl groups represented by ^R2 in the monomer unit A, the value of Ac is calculated as follows: For example, when ^R2 in the monomer unit A contains _Xa mass % of (meth)acrylic acid ester, _which is a linear alkyl group having n carbon atoms, and Y _a mass % of (meth)acrylic acid ester, which is an alkyl group having _m carbon atoms, the above Ac is calculated from the following formula (6):
Ac=(n _a X _a + m _a Y _a )/100... (6)

If multiple types of ester waxes are present, the value of |Ac - Wc| is calculated using the calculated Ac and the Wc of each ester wax, and it is determined for each ester wax whether the value of |Ac - Wc| is within the above range. In other words, it is preferable to contain ester waxes whose |Ac - Wc| value falls within the above range. It is also possible to contain ester waxes whose |Ac - Wc| value does not fall within the above range.

In addition, in the present disclosure, the ester wax is preferably an ester of a trivalent or higher alcohol and an aliphatic monocarboxylic acid. It is more preferably an ester of a tetravalent or higher alcohol and an aliphatic monocarboxylic acid, and even more preferably an ester of a hexavalent or higher alcohol and an aliphatic monocarboxylic acid.

The valence of the trihydric or higher alcohol corresponds to the number of branched structures in the ester wax. By using a wax with a branched structure, the vinyl polymer A and the wax tend to form a eutectic, which tends to improve durability and releasability. The reason why a eutectic is more likely to form is thought to be that the branched wax makes it easier for ^R2 of the monomer unit A in the vinyl polymer A to enter the gaps between the wax crystals. Furthermore, it is thought that the intrusion of ^R2 into the gaps between the wax makes it easier for the wax in the toner particles to form a network structure, which makes it less likely for the boundary between the wax and the resin component to become clear and less likely to become a starting point for cracking and chipping of the toner.

It is preferable that the toner particles further contain a hydrocarbon wax as the wax. One type of hydrocarbon wax may be used alone, or two or more types may be used in combination.

There are no particular limitations on hydrocarbon waxes, but examples include the following:

Aliphatic hydrocarbon waxes: low molecular weight polyethylene, low molecular weight polypropylene, low molecular weight olefin copolymers, Fischer-Tropsch wax, or waxes obtained by oxidizing or adding acids to these.

The ratio of the mass of wax to the mass of the resin component is preferably 1.0 to 25.0% by mass. A ratio of 1.0% by mass or more makes it easier to obtain a toner with excellent release properties. Therefore, it is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, and even more preferably 5.0% by mass or more. Furthermore, a ratio of 25.0% by mass or less makes it less likely that the amount of a single wax in the toner particles will be excessive, making it less likely that the toner will crack or chip. Therefore, it is preferably 25.0% by mass or less, more preferably 20.0% by mass or less, and even more preferably 15.0% by mass or less. If the toner particles contain multiple types of wax, the total mass of those waxes is used for the calculation.

The molecular weight of the wax is preferably 1000 to 3000. If the molecular weight of the wax is 1000 or more, it is believed that the compatibility between the vinyl polymer A and the wax becomes poor, making it easier to obtain a toner with excellent low-temperature fixability, heat-resistant storage stability, and releasability. Therefore, it is preferably 1000 or more, and more preferably 1500 or more. Furthermore, if it is 3000 or less, the toner's releasability is more likely to be maintained appropriately. Therefore, it is preferably 3000 or less, and more preferably 2500 or less.

It is preferable that the melting point of the wax is higher than the melting point of the vinyl polymer A contained in the toner. This is preferable because controlling the melting point as described above and carrying out the heat treatment described below in the toner manufacturing process makes it easier to produce a toner that satisfies the above-mentioned range of luminance M - luminance N values.

Moreover, it is more preferable that the melting point of the wax is 60 to 120°C. It is believed that a wax melting point within this range makes it easier for the wax to melt and seep out onto the surface of the toner particles during fixing. A melting point of 70 to 100°C is even more preferable.

<Core-shell structure>
The toner of the present disclosure may have a core having a resin component and a wax, and a shell phase that covers the core.

The resin that forms the shell phase can be any of the resins listed above as usable resins other than vinyl polymer A as a resin component. Among these, vinyl resins and polyesters are preferred from the standpoint of charge stability.

<Various additives>
If necessary, the toner may contain one or more additives selected from colorants, magnetic materials, charge control agents, fluidizing agents, etc. Various additives used in the toner will be specifically described below.

<Coloring Agent>
The coloring agents include the following:

Yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds. Specifically, C.I. Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, 155, 168, and 180 are preferably used.

Magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Specifically, C.I. Pigment Red 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, and 254 are preferred.

Cyan colorants include copper phthalocyanine compounds and their derivatives, anthraquinone compounds, and basic dye lake compounds. Specifically, C.I. Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, and 66 are preferably used.

The colorants used in the toner of the present disclosure are selected based on their hue angle, saturation, brightness, lightfastness, transparency on overhead projectors (OHPs), and dispersibility in toner particles.

If the colorant is not magnetic particles, the colorant is preferably contained in an amount of 1.0 to 20.0 parts by mass per 100.0 parts by mass of the resin component. If magnetic particles are used as the colorant, the amount added is preferably 40.0 parts by mass or more and 150.0 parts by mass or less per 100.0 parts by mass of the resin component.

<Charge control agent>
The charge control agent can be used without any particular limitation.

Examples of negative charge control agents include:

Monoazo metal compounds, acetylacetone metal compounds, aromatic oxycarboxylic acids, aromatic dicarboxylic acids, oxycarboxylic acid and dicarboxylic acid metal compounds.

Examples of positive charge control agents include quaternary ammonium salts, polymeric compounds having quaternary ammonium salts in their side chains; guanidine compounds; pyridine-based compounds; nigrosine-based compounds; and imidazole compounds.

The charge control agent is preferably contained in an amount of 0.01 to 20.0 parts by weight per 100.0 parts by weight of toner particles. It is more preferably contained in an amount of 0.5 to 10.0 parts by weight.

<External additives>
Examples of external additives include the following:

Inorganic particles selected from the group consisting of silica particles, alumina particles, and titania particles, or composite oxides thereof. Examples of composite oxides include silica aluminum particles and strontium titanate particles.

The amount of external additive contained is preferably 0.01 to 8.0 parts by weight per 100 parts by weight of toner particles. It is even more preferable that the amount be 0.1 to 4.0 parts by weight.

<Toner manufacturing method>
The toner and toner particles may be produced by any method, including, but not limited to, a pulverization method, a suspension polymerization method, an emulsion aggregation method, a solution suspension method, etc. Among the above, the suspension polymerization method is preferred.

To satisfy the above range of brightness M - brightness N values, it is preferable to control the content of vinyl polymer A and wax and heat-treat the toner particles for 30 minutes or more at a temperature between the melting points of vinyl polymer A and the wax.

That is, the method for producing a toner according to the present disclosure is
a step of obtaining toner base particles containing wax and a resin component; and a step of obtaining toner particles by heat-treating the toner base particles for 30 minutes or more in a temperature range of TmA to TmW, where TmW is the melting point of the wax and TmA is the melting point of the vinyl polymer A.
It is preferable that the toner manufacturing method has the following features.

To ensure that the above-mentioned range of luminance M - luminance N values is easily met, it is preferable that the content of vinyl polymer A in the resin component be 30.0% by mass or more, and that the content of wax relative to the mass of the resin component be 1.0 to 25.0% by mass.

Furthermore, when the heat treatment temperature is in the range of TmA to TmW, it is believed that the wax crystallizes preferentially over the vinyl polymer A, making it easier for a eutectic structure between the wax and vinyl polymer A to be incorporated into the toner particles, and making the value of luminance M - luminance N larger, which is preferable. It is also preferable that TmA < TmW.

It is also preferable to raise the temperature of the toner particles to TmW or higher before the heat treatment step. This makes it easier for the vinyl polymer A and wax contained in the toner particles to enter a molten state, and by subsequently carrying out the heat treatment step, it is thought that crystallization of the mixed components proceeds under conditions favorable to the wax, making it easier for a eutectic structure to form.

In addition, it is believed that carrying out the heat treatment for 30 minutes or longer makes it easier to preferentially and sufficiently crystallize the wax contained in the toner particles. Therefore, it is preferably 30 minutes or longer, more preferably 1 hour or longer, and even more preferably 2.5 hours or longer. There is no particular upper limit, but it is preferably 5 hours or less.

<Step of Obtaining Toner Particles>
The step of obtaining the toner particles is preferably a step of obtaining toner particles by a suspension polymerization method. In producing toner particles by the suspension polymerization method, a polymerizable monomer composition containing a polymerizable monomer, a wax, and optionally a colorant, etc. is added to an aqueous medium, and the polymerizable monomer composition is granulated in the aqueous medium to form particles of the polymerizable monomer composition. Then, the polymerizable monomer contained in the particles of the polymerizable monomer composition is polymerized to produce a resin component, thereby obtaining toner particles.

The above-mentioned process for obtaining toner particles may also be a process for obtaining toner particles by a pulverization method. To produce toner particles by the pulverization method, first, toner components such as a resin material containing vinyl polymer A, wax, and, if necessary, a colorant, are mixed. These are thoroughly mixed using a mixer such as a Henschel mixer or ball mill. Next, the mixture is melted using a thermal mixer such as a roll, kneader, or extruder. The mixture is then kneaded and mixed to make the resins and other components compatible with each other, and various materials are dispersed in the mixture. After cooling and solidifying, the mixture is pulverized and classified to obtain toner particles.

The above-mentioned process for obtaining toner particles may also be a process for obtaining toner particles by emulsion aggregation. In producing toner particles by emulsion aggregation, an aqueous dispersion of a resin material containing vinyl polymer A, wax, and, if necessary, a colorant, etc., is prepared (aqueous dispersion process), mixed, and then aggregated to the desired particle size using a metal salt or the like (aggregation process). The resulting aggregates are heated to fuse them (heat fusion process), and then cooled and washed and dried to obtain toner particles.

The above-mentioned process for obtaining toner particles may also be a process for obtaining toner particles by a solution suspension method. In producing toner particles by the solution suspension method, first, a resin material containing vinyl polymer A, wax, and, if necessary, a colorant, etc. are dissolved or dispersed in an organic solvent (resin dissolution process). The resulting solution or dispersion is then dispersed in a poor solvent such as water to obtain granules (droplets) of approximately the size of toner particles (granulation process). The organic solvent contained in the obtained granules is distilled off (solvent removal process), and the granules are then washed and dried (washing and drying process) to obtain toner particles.

<Various measurement methods, etc.>
Various measurement methods will be described below.

<Acquisition of cross-sectional images of toner particles using a scanning transmission electron microscope (STEM)>
The state of wax in the toner particles is confirmed by observing the cross section of the toner particles using a scanning transmission electron microscope. The cross section of the toner particles is observed after ruthenium staining. That is, the cross section image of the toner particles according to the present disclosure is preferably a cross section image of the toner particles stained with ruthenium.

The procedure for observing the cross section of toner is as follows:

The toner is embedded in a visible light curing resin (D-800, manufactured by Nissin EM Co., Ltd.) so that it is as dispersed as possible, and then cut to a thickness of 100 nm using an ultrasonic ultramicrotome (UC7, manufactured by Leica).

The obtained thin section sample was stained for 15 minutes in a 500 Pa _RuO4 gas atmosphere using a vacuum staining apparatus (VSC4R1H, manufactured by Filgen), and a STEM image was obtained using a scanning transmission electron microscope (JEM2800, manufactured by JEOL). Under the above staining conditions, there is a difference in the degree of staining between the crystallized wax and the resin, and the presence of the wax can be confirmed by the contrast difference. The observation conditions were set to an acceleration voltage of 200 kV, a STEM probe size of 1 nm, an image size of 1024 x 1024 pixels, and a magnification of 30,000, and a dark field (STEM-DF) image was obtained. Contrast and brightness were adjusted so that the brightness of the portion mainly composed of the resin component was 150 in the brightness histogram obtained by IMAGE J below. In addition, the brightness of the wax in the cross section of the toner particle was adjusted to 0.

When selecting toner particles for which cross-sectional images are to be obtained, the weight-average particle size (D4) of the toner is measured using the measurement method described below, and then 10 toner particles with a major axis diameter that is 0.8 to 1.1 times the D4 are randomly selected. Furthermore, images are obtained so that no more than two toner particles are within the field of view of a single image.

<Brightness histogram and physical property values obtained from the histogram>
The brightness histogram is obtained by analyzing the STEM image of the toner particle cross section obtained by the above method using image processing software Image J (developed by Wayne Rashand). That is, the brightness histogram is preferably a brightness histogram obtained when a 256-level brightness spectrum is measured for the image obtained by image analysis of the toner particle cross section. The specific procedure is shown below.

First, convert the backscattered electron image to be analyzed to 8-bit from the Type menu in the Image menu.

Next, specify the analysis range to be only the area inside the toner outline. Here, the boundary of the toner outline is the interface between the visible light curable resin and the toner cross section. Erase the area outside the analysis range by selecting Clear Outside from the Edit menu.

In the Filters section of the Process menu, set the Median diameter to 2.0 pixels to reduce image noise.

Next, select Histogram from the Analyze menu to display the luminance histogram in a new window. Also, obtain the luminance histogram values from the List in that window. The obtained values are used to calculate the following values:
The range of brightness values in which the number of pixels at brightness P is 20% or more in the brightness range of 10 to 245. The total number of pixels C at brightness 0 to 9, and the total number of pixels A at brightness 0 to 245
In the acquired histogram, if the brightness X, where the number of pixels with a brightness of 10 to 245 is the maximum value P, is between 140 and 160, the brightness of the STEM image may be adjusted using the video editing software Microsoft Photos (Microsoft Corporation). In this case, the STEM image, from which all areas except the analysis range have been erased using IMAGE J, is opened in the video editing software Microsoft Photos. Select Edit from the Edit and Create menu, and move the light cursor on the adjustment screen to adjust the brightness so that brightness X is 150.

After adjusting the brightness, open the STEM image again in IMAGE J, select the area inside the toner outline as the analysis range, and obtain a brightness histogram. Obtain the brightness histogram values from the list of the obtained brightness histogram.

Also, if the brightness P is not within the range of 140 or greater and less than 160, it is necessary to acquire the STEM image again so that the brightness P becomes 150.

Similar image analysis is performed on 10 STEM images of each toner, and the above values are calculated. The average of the obtained values for the 10 images is used as the physical property value for each toner.

<Method for measuring the content of various monomer units in a resin>
The content ratio of each monomer unit in the resin is measured by ¹ H-NMR under the following conditions.
Measuring device: FT NMR device JNM-EX400 (manufactured by JEOL Ltd.)
Measurement frequency: 400 MHz
Pulse condition: 5.0 μs
Frequency range: 10,500 Hz
Number of measurements: 64 Measurement temperature: 30°C
Sample: 50 mg of a measurement sample is placed in a sample tube with an inner diameter of 5 mm, deuterated chloroform (CDCl ₃ ) is added as a solvent, and the sample is dissolved in a thermostatic bath at 40°C.

The obtained ¹ H-NMR chart is analyzed to identify the structure of each monomer unit. Here, as an example, the measurement of the content ratio of monomer unit A in vinyl polymer A will be described. In the obtained ¹ H-NMR chart, a peak independent of the peaks attributable to the constituent elements of monomer unit A is selected from the peaks attributable to the constituent elements of other monomer units, and the integral value S1 of this peak is calculated. The integral values of the other monomer units contained in vinyl polymer A are also calculated in the same manner.

When the monomer units constituting vinyl polymer A are monomer unit A and one other monomer unit, the content of monomer unit A is determined as follows using the above-mentioned integral value S1 and the integral value S2 of the peak of the other monomer unit. Note that n1 and n2 are the numbers of hydrogen atoms in the constituent elements to which the peak of interest for each site belongs.

Content of Monomer Unit A (mol %)=
{(S1/n1)/((S1/n1)+(S2/n2))}×100
Even when two or more other monomer units are present, the content of the monomer unit A can be calculated in the same manner.

When a polymerizable monomer containing no hydrogen atoms in components other than the vinyl group is used, the measurement is performed using ¹³ C-NMR with ¹³ C as the measurement nucleus in single pulse mode, and the calculation is performed in the same manner using ¹ H-NMR.

The proportion (mol %) of each unit calculated using the above method is multiplied by the molecular weight of each unit to convert the content of each unit into mass %.

Furthermore, when NMR is measured using a toner sample, the peaks of wax and resins other than vinyl polymer A may overlap, making it impossible to observe independent peaks. This may make it impossible to calculate the content of each unit in vinyl polymer A. In such cases, vinyl polymer A' can be produced by carrying out the same production process without using wax or other resins, and this can be analyzed as vinyl polymer A.

<Method for measuring weight average molecular weight (Mw) of resin>
The weight average molecular weight (Mw) of the resin is measured by gel permeation chromatography (GPC) as follows.

First, a sample is dissolved in tetrahydrofuran (THF) at room temperature for 24 hours. The resulting solution is then filtered through a solvent-resistant membrane filter "Myshoridisc" (manufactured by Tosoh Corporation) with a pore size of 0.2 μm to obtain a sample solution. The sample solution is adjusted so that the concentration of components soluble in THF is 0.8 mass%. This sample solution is used for measurements under the following conditions.
Apparatus: HLC8120 GPC (detector: RI) (manufactured by Tosoh Corporation)
Column: 7 columns of Shodex KF-801, 802, 803, 804, 805, 806, and 807 (manufactured by Showa Denko K.K.)
Eluent: tetrahydrofuran (THF)
Flow rate: 1.0 mL/min Oven temperature: 40.0°C
Sample injection volume: 0.10 mL

When calculating the molecular weight of a sample, a molecular weight calibration curve created using standard polystyrene resins (for example, trade names "TSK Standard Polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500", manufactured by Tosoh Corporation) is used.

<Measurement of wax molecular weight>
The molecular weight of the release agent is measured by gel permeation chromatography (GPC) as follows: Special grade 2,6-di-t-butyl-4-methylphenol (BHT) is added to o-dichlorobenzene for gel chromatography to a concentration of 0.10 mass/volume % and dissolved at room temperature.

The release agent and the o-dichlorobenzene to which the BHT has been added are placed in a sample bottle and heated on a hot plate set to 150°C to dissolve the release agent. Once the release agent has dissolved, it is placed in a preheated filter unit and installed in the main body. The sample that has passed through the filter unit is used as the GPC sample. The sample solution is adjusted to have a concentration of 0.15% by mass. Measurements are performed using this sample solution under the following conditions.
Apparatus: HLC-8121GPC/HT (manufactured by Tosoh Corporation)
Detector: High temperature RI
Column: TSKgel GMHHR-H HT 2-column (manufactured by Tosoh Corporation)
・Temperature: 135.0℃
Solvent: o-dichlorobenzene for gel chromatography (containing 0.10% by mass/volume of BHT)
・Flow rate: 1.0mL/min ・Injection volume: 0.4mL

When calculating the molecular weight of the release agent, a molecular weight calibration curve created using standard polystyrene resins (for example, trade names "TSK Standard Polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500" manufactured by Tosoh Corporation) is used.

<Method for measuring melting point>
The melting point is measured using a DSC Q1000 (manufactured by TA Instruments) under the following conditions.

Temperature rise rate: 10°C/min Measurement start temperature: 20°C
Measurement end temperature: 180°C
The melting points of indium and zinc are used to correct the temperature of the detector, and the heat of fusion of indium is used to correct the amount of heat.

Specifically, 5 mg of sample is precisely weighed and placed in an aluminum pan, and differential scanning calorimetry is performed. An empty silver pan is used as a reference.

The peak temperature of the maximum endothermic peak during the first heating process is taken as the melting point.

Note that the maximum endothermic peak is the peak with the greatest amount of endothermic heat when there are multiple peaks.

<Measurement of Weight Average Particle Size (D4) of Toner>
The weight average particle size (D4) of the toner is calculated as follows. As a measuring device, a precision particle size distribution measuring device using the pore electrical resistance method, "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter, Inc.), equipped with a 100 μm aperture tube, is used. The measurement conditions are set and the measurement data is analyzed using the accompanying dedicated software, "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter, Inc.). The measurement is performed using an effective number of measurement channels of 25,000.

The aqueous electrolyte solution used for the measurement is prepared by dissolving special-grade sodium chloride in ion-exchange water to a concentration of 1.0%, such as "ISOTON II" (manufactured by Beckman Coulter, Inc.).

Before performing measurements and analysis, configure the dedicated software as follows:

On the "Change Standard Measurement Method (SOMME)" screen of the dedicated software, set the total count in control mode to 50,000 particles, the number of measurements to 1, and the Kd value to the value obtained using "Standard Particle 10.0 μm" (manufactured by Beckman Coulter, Inc.). Press the "Threshold/Noise Level Measurement Button" to automatically set the threshold and noise level. Also, set the current to 1,600 μA, gain to 2, and electrolyte to ISOTON II, and check "Flush aperture tube after measurement."

On the dedicated software's "Pulse to particle size conversion settings" screen, set the bin spacing to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range to 2 μm to 60 μm.

The specific measurement method is as follows.
(1) Pour 200.0 mL of the electrolyte solution into a 250 mL round-bottom glass beaker made specifically for the Multisizer 3, set it on the sample stand, and stir the stirrer rod counterclockwise at 24 revolutions per second. Then, use the "Aperture Tube Flush" function of the dedicated software to remove any dirt and air bubbles from inside the aperture tube.
(2) 30.0 mL of the aqueous electrolyte solution is placed in a 100 mL flat-bottom glass beaker, and 0.3 mL of a dilution of "Contaminon N" (a 10% aqueous solution of a neutral detergent for cleaning precision measuring instruments, pH 7, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) diluted 3 times by mass with ion-exchanged water is added as a dispersant.
(3) Prepare an ultrasonic disperser "Ultrasonic Dispersion System Tetra150" (manufactured by Nikkaki Bios Co., Ltd.) with an electrical output of 120 W and two built-in oscillators with an oscillation frequency of 50 kHz and a phase difference of 180 degrees. 3.3 L of ion-exchanged water is placed in the water tank of the ultrasonic disperser, and 2.0 mL of Contaminon N is added to this water tank.
(4) The beaker (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. Then, the height of the beaker is adjusted so that the resonance state of the liquid surface of the electrolytic solution in the beaker is maximized.
(5) While the electrolyte solution in the beaker in (4) is being irradiated with ultrasonic waves, 10 mg of toner particles are added little by little to the electrolyte solution and dispersed. The ultrasonic dispersion process is then continued for another 60 seconds. During the ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be between 10°C and 40°C.
(6) Using a pipette, the electrolytic solution prepared in (5) above, in which toner particles have been dispersed, is dropped into the round-bottom beaker prepared in (1) above placed in the sample stand, and the measurement concentration is adjusted to 5%. Then, measurements are continued until the number of particles measured reaches 50,000.
(7) The measurement data is analyzed using the dedicated software provided with the device to calculate the weight-average particle size (D4). Note that when the dedicated software is set to graph/volume %, the "average diameter" on the "analysis/volume statistics (arithmetic mean)" screen is the weight-average particle size (D4).

The present disclosure will be specifically described below using examples, but these examples are not intended to limit the present disclosure in any way. In the following formulations, parts are by mass unless otherwise specified. Examples 7 to 9 and 24 to 30 are reference examples.

The measurement results in the examples were obtained using the measurement methods described above. The 50% particle size (D50) based on the volume distribution of the dispersion was measured using a dynamic light scattering particle size distribution analyzer, Nanotrac UPA-EX150 (manufactured by Nikkiso).

<Production example of shell resin>
The following materials were placed in an autoclave equipped with a pressure reducing device, a water separating device, a nitrogen gas introducing device, a temperature measuring device, and a stirring device.
Terephthalic acid 32.3 parts by mass (50.0 mol%)
Bisphenol A-propylene oxide 2-mol adduct 67.7 parts by mass (50.0 mol%)
A reaction was carried out for 8 hours under a nitrogen atmosphere at normal pressure at 220°C to obtain an amorphous polyester shell resin. The weight average molecular weight (hereinafter also referred to as Mw) and glass transition temperature (Tg) of the obtained shell resin were measured, and the Mw was 20,000 and the Tg was 70°C.

<Wax used in toner production>
Table 1 shows the types and properties of the waxes used in the production of the toner.

<Production Example of Toner 1>
[Toner Production by Suspension Polymerization Method]
(Preparation of Toner Particles 1)
The following materials were charged into an attritor (manufactured by Nippon Coke Company).
Methacrylonitrile (monomer (b)) 25.0 parts Styrene (monomer (c)) 10.0 parts Ethyl methacrylate (monomer (d)) 15.0 parts Colorant Pigment Blue 15:3 6.5 parts A raw material dispersion was obtained by dispersing for 2 hours at 200 rpm using zirconia beads having a diameter of 5 mm.

Meanwhile, 735.0 parts of ion-exchanged water and 16.0 parts of trisodium phosphate dodecahydrate were added to a vessel equipped with a high-speed homomixer (manufactured by Primix Corporation) and a thermometer, and the temperature was raised to 60°C while stirring at 12,000 rpm. Next, an aqueous calcium chloride solution prepared by dissolving 9.0 parts of calcium chloride dihydrate in 65.0 parts of ion-exchanged water was added to the vessel, and the mixture was stirred at 12,000 rpm for 30 minutes while maintaining the temperature at 60°C. 10% hydrochloric acid was added to the mixture to adjust the pH to 6.0, yielding an aqueous medium in which a dispersion stabilizer containing hydroxyapatite was dispersed in water.

Subsequently, the raw material dispersion liquid was transferred to a container equipped with a stirrer and a thermometer, and the temperature was raised to 60° C. while stirring at 100 rpm. The following materials were then added thereto.
- Behenyl acrylate (monomer (a)) 50.0 parts - Shell resin 4.0 parts - Wax 1 9.0 parts After stirring at 100 rpm for 30 minutes while maintaining the temperature at 60°C, 5.0 parts of t-butyl peroxypivalate (Perbutyl PV, manufactured by NOF Corporation) as a polymerization initiator was added and stirred for another minute, and then the mixture was poured into the aqueous medium being stirred at 12,000 rpm with the above-mentioned high-speed stirrer. While maintaining the temperature at 60°C, stirring was continued for 20 minutes at 12,000 rpm with the above-mentioned high-speed stirrer to obtain a granulation liquid.

The granulation liquid was transferred to a reaction vessel equipped with a reflux condenser, a stirrer, a thermometer, and a nitrogen inlet tube, and heated to 70°C while stirring at 150 rpm under a nitrogen atmosphere. The polymerization reaction was carried out at 150 rpm for 12 hours while maintaining the temperature at 70°C, yielding a toner particle dispersion.

The resulting toner particle dispersion was heated to 95°C and stirred at 150 rpm for 1 hour while maintaining the temperature at 95°C. It was then cooled to 70°C while stirring, and heat-treated for 3 hours while maintaining the temperature at 70°C. After heat treatment, the mixture was cooled to 30°C, and while continuing to stir, dilute hydrochloric acid was added until the pH reached 1.5 to dissolve the dispersion stabilizer. The solids were then filtered off, thoroughly washed with ion-exchanged water, and vacuum-dried at 30°C for 24 hours to obtain toner particles 1 containing polymer A1.

2.0 parts of silica fine particles (hydrophobized with hexamethyldisilazane, primary particle number-average particle size: 10 nm) were added as an external additive to 100.0 parts of toner particles 1, and the mixture was mixed for 15 minutes at 3,000 rpm using an FM mixer (manufactured by Nippon Coke & Engineering Co., Ltd.) to obtain toner 1. Figure 1 shows one of ten 256-level brightness histograms obtained from STEM images of the cross section of the obtained toner 1. In Figure 1, the brightness X was 150, P was 7,336 particles, brightness M was 215, and brightness N was 30. The physical properties of toner 1 are shown in Tables 5 and 6.

<Production Examples of Toners 2 to 20 and 27 to 38>
Toners 2 to 20 and 27 to 38 were obtained by carrying out the same operations as in the production example of Toner 1, except that the type and amount of monomer used were changed as shown in Table 2, and the type and amount of wax added, and the temperature and time of heat treatment were changed as shown in Table 3. The physical properties of Toners 2 to 20 and 27 to 38 are shown in Tables 5 and 6.

Figure 2 shows one of ten 256-level brightness histograms obtained from STEM images of the cross section of the resulting toner 35. In Figure 2, the brightness X was 150, P was 15,709 particles, brightness M was 179, and brightness N was 120.

The abbreviations in Table 2 are as follows:
BEA: Behenyl acrylate STA: Stearyl acrylate OCA: Octacosa acrylate MYA: Myristyl acrylate CEA: Cetyl acrylate MN: Methacrylonitrile VA: Vinyl acetate St: Styrene VBA: Vinyl benzoate ME: Ethyl methacrylate AB: Butyl acrylate

In Table 3, Toner 14 and Toner 38 were not heat-treated.

<Production Example of Toner 21>
(Production Example of Polymer A2)
The following materials were placed in a reaction vessel equipped with a reflux condenser, a stirrer, a thermometer, and a nitrogen inlet tube under a nitrogen atmosphere.
Toluene 100.0 parts by mass Monomer composition 100.0 parts by mass (The monomer composition was a mixture of behenyl acrylate, methacrylonitrile, ethyl methacrylate, and styrene in the ratios shown below.
Behenyl acrylate (monomer (a)) 50.0 parts by mass, methacrylonitrile 25.0 parts by mass, ethyl methacrylate 15.0 parts by mass, styrene 10.0 parts by mass)
t-Butyl peroxypivalate (Perbutyl PV, manufactured by NOF Corporation) 0.5 parts

The reactor was heated to 70°C while stirring at 200 rpm and the polymerization reaction was carried out for 12 hours, yielding a solution in which the monomer composition polymer was dissolved in toluene. The resulting solution was then cooled to 25°C and poured into 1,000.0 parts of methanol while stirring, causing the methanol-insoluble matter to precipitate. The resulting methanol-insoluble matter was filtered off, washed with methanol, and vacuum-dried at 40°C for 24 hours to yield Polymer A2.

[Toner production by pulverization method]
Polymer A2 100.0 parts by mass Colorant Pigment Blue 15:3 (manufactured by Dainichiseika Chemicals) 6.5 parts by mass Wax 1 9.0 parts by mass Charge control agent (LR147: manufactured by Nippon Carlit Co., Ltd.) 2.0 parts by mass

The above materials were premixed in an FM mixer (manufactured by Nippon Coke and Engineering Co., Ltd.), and then melt-mixed at a discharge temperature of 135°C in a twin-screw kneading extruder (PCM-30 model manufactured by Ikegai Iron Works Co., Ltd.) set to a temperature of 120°C to obtain a kneaded mixture.

During the cooling process, the resulting kneaded material was heat-treated by holding it at 95°C for 1 hour and then at 70°C for 3 hours. The heat-treated kneaded material was coarsely pulverized using a hammer mill and then pulverized using a mechanical pulverizer (T-250, manufactured by Turbo Kogyo Co., Ltd.) to obtain finely pulverized powder. The resulting finely pulverized powder was classified using a multi-division classifier that utilizes the Coanda effect to obtain toner particles 21 with a weight-average particle size (D4) of 7.0 μm.

To 100.0 parts of toner particles 21, 2.0 parts of silica fine particles (hydrophobized with hexamethyldisilazane, primary particle number average particle size: 10 nm) were added as an external additive, and the mixture was mixed at 3,000 rpm for 15 minutes using an FM mixer (manufactured by Nippon Coke & Engineering Co., Ltd.) to obtain toner 21. The physical properties of toner 21 are shown in Tables 5 and 6.

<Production Example of Toner 22>
[Toner Production by Emulsion Aggregation Method]
(Preparation of Polymer A2 Dispersion)
Toluene 300.0 parts by mass Polymer A2 100.0 parts by mass The above materials were weighed and mixed, and Polymer A2 was dissolved at 90° C. to obtain a toluene solution.

Separately, 5.0 parts by mass of sodium dodecylbenzenesulfonate and 10.0 parts by mass of sodium laurate were added to 700.0 parts by mass of ion-exchanged water and dissolved by heating at 90°C to obtain an aqueous solution. The toluene solution and the aqueous solution were then mixed and stirred at 7,000 rpm using an ultra-high-speed stirring device, T.K. Robomix (manufactured by Primix). The mixture was then emulsified at a pressure of 200 MPa using a high-pressure impact disperser, Nanomizer (manufactured by Yoshida Kikai Kogyo). The toluene was then removed using an evaporator, and the concentration was adjusted with ion-exchanged water to obtain a polymer A2 dispersion containing 20% by mass of polymer A2 microparticles.

The 50% particle size (D50) based on volume distribution was measured for the polymer A2 dispersion and found to be 0.40 μm.

(Preparation of Wax Dispersion 1)
Wax 1 100.0 parts by mass Anionic surfactant Neogen RK (manufactured by Daiichi Kogyo Seiyaku) 5.0 parts by mass Ion-exchanged water 395.0 parts by mass

The above materials were placed in a mixing vessel equipped with a stirrer and heated to 90°C. Then, the mixture was circulated through a Clearmix W Motion (manufactured by M Technique) and subjected to a dispersion treatment for 60 minutes under the following conditions:
Rotor outer diameter: 3cm
Clearance: 0.3 mm
Rotor rotation speed: 19,000 rpm
・Screen rotation speed: 19,000 rpm

After dispersion, the mixture was cooled to 40°C under cooling conditions of a rotor rotation speed of 1000 rpm, a screen rotation speed of 0 rpm, and a cooling rate of 10°C/min, yielding Wax Dispersion 1 containing 20% by mass of Wax 1 microparticles.

The volume-based 50% particle size (D50) of the Wax 1 microparticles was measured and found to be 0.15 μm.

(Preparation of Colorant Dispersion 1)
Colorant (Pigment Blue 15:3) 50.0 parts by mass Anionic surfactant NEOGEN RK (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) 7.5 parts by mass Ion-exchanged water 442.5 parts by mass The above materials were weighed, mixed, dissolved, and dispersed for 1 hour using a high-pressure impact disperser Nanomizer (manufactured by Yoshida Kikai Kogyo Co., Ltd.) to obtain colorant dispersion liquid 1 containing 10% by mass of colorant microparticles.

The 50% particle size (D50) of the above colorant particles based on volume distribution was measured and found to be 0.20 μm.

(Preparation of Toner 22)
The following materials were placed in a round stainless steel flask and mixed.
Polymer A2 dispersion 500.0 parts by mass Wax dispersion 1 45.0 parts by mass Colorant dispersion 1 80.0 parts by mass Ion-exchanged water 160.0 parts by mass

After mixing, the mixture was dispersed at 5,000 rpm for 10 minutes using an Ultra Turrax T50 homogenizer (manufactured by IKA Corporation). A 1.0% aqueous nitric acid solution was added, and the pH was adjusted to 3.0. The mixture was then heated to 58°C in a heated water bath using a stirring blade, while adjusting the rotation speed appropriately to stir the mixture. The formed aggregated particles were checked as needed, and when aggregated particles with a weight-average particle size (D4) of 6.0 μm were formed, 5% aqueous sodium hydroxide solution was added, and the pH was adjusted to 9.0. The mixture was then heated to 75°C while continuing to stir. The aggregated particles were fused by holding at 75°C for 1 hour.

Then, the temperature was raised to 90°C, and the material was maintained at 90°C for 1 hour, and then heat-treated at 70°C for 3 hours.

After the heat treatment, the mixture was cooled to 30°C, filtered, and subjected to solid-liquid separation, followed by washing with ion-exchanged water. After washing, the mixture was dried using a vacuum dryer to obtain toner particles 22 with a weight-average particle size (D4) of 6.1 μm.

To 100.0 parts of toner particles 22, 2.0 parts of silica fine particles (hydrophobized with hexamethyldisilazane, primary particle number average particle size: 10 nm) were added as an external additive, and the mixture was mixed at 3,000 rpm for 15 minutes using an FM mixer (manufactured by Nippon Coke & Engineering Co., Ltd.) to obtain toner 22. The physical properties of toner 22 are shown in Tables 5 and 6.

<Production Example of Toner 23>
[Toner Production by Dissolution Suspension Method]
(Preparation of Colorant Dispersion 2)
The following materials were placed in a heat-resistant glass container.
Colorant (Pigment Blue 15:3) 100.0 parts by mass Ethyl acetate 150.0 parts by mass Glass beads (1 mm) 200.0 parts by mass

After dispersing for 5 hours using a paint shaker, the glass beads were removed using a nylon mesh to obtain Colorant Dispersion 2. The 50% particle size (D50) based on volume distribution of Colorant Dispersion 2 was measured and found to be 0.20 μm.

(Preparation of Wax Dispersion 2)
The above materials were placed in a sealable reaction vessel and heated and stirred at 80° C. Subsequently, the system was cooled to 25° C. over 3 hours while gently stirring at 50 rpm, yielding a milky white liquid.

This solution was placed in a heat-resistant container along with 30.0 parts by mass of 1 mm diameter glass beads and dispersed for 3 hours using a paint shaker (manufactured by Toyo Seiki Seisaku-sho). After that, the glass beads were removed using a nylon mesh to obtain Wax Dispersion 2. The 50% particle size (D50) based on volume distribution of Wax Dispersion 2 was measured and found to be 0.23 μm.

(Preparation of oil phase)
The following materials were placed in a beaker and stirred at 3000 rpm for 1 minute using a Disper (manufactured by Tokushu Kika Co., Ltd.).
Polymer A2 100.0 parts by mass Ethyl acetate 85.0 parts by mass The following materials were further added to the beaker and stirred at 6000 rpm for 3 minutes using a Disper (manufactured by Tokushu Kika Co., Ltd.) to prepare an oil phase.
Wax dispersion 2 (solid content: 20% by mass) 45.0 parts by mass Colorant dispersion 2 (solid content: 40% by mass) 12.5 parts by mass Ethyl acetate 5.0 parts by mass

(Preparation of aqueous phase)
Aqueous solution of sodium dodecyldiphenyletherdisulfonate (Eleminol MON7, manufactured by Sanyo Chemical Industries, Ltd.) 100.0 parts by mass Ion-exchanged water 900.0 parts by mass The above materials were placed in a beaker and stirred at 3000 rpm for 3 minutes using a Disper (manufactured by Tokushu Kika Co., Ltd.) to prepare an aqueous phase.

(Preparation of Toner 23)
The oil phase was added to the aqueous phase and dispersed at 10,000 rpm for 10 minutes using a T.K. Homomixer (manufactured by Tokushu Kika Co., Ltd.). Then, the solvent was removed for 30 minutes at 30 ° C. and a reduced pressure of 50 mmHg. The obtained slurry was heated and stirred for 1 hour while maintaining the temperature at 90 ° C. Then, it was cooled to 70 ° C. and heat-treated for 3 hours while maintaining the temperature at 70 ° C. Subsequently, filtration was performed, and the operation of filtration and re-dispersion in ion-exchanged water was repeated five times to remove the surfactant, and a filter cake was obtained.

The filter cake was vacuum dried and then air-classified to obtain toner particles 23.

Toner particles 23 were externally added in the same manner as Toner 1 to obtain Toner 23. The physical properties of Toner 23 are shown in Tables 5 and 6.

<Production Examples of Toners 24 to 26>
(Preparation of amorphous resin 1)
The following materials were placed in a heated and dried two-necked flask while introducing nitrogen.
Polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane 30.0 parts by mass Polyoxyethylene (2.2)-2,2-bis(4-hydroxyphenyl)propane 33.0 parts by mass Terephthalic acid 21.0 parts by mass Dodecenylsuccinic acid 15.0 parts by mass Dibutyltin oxide 0.1 parts by mass

After replacing the atmosphere in the system with nitrogen, the mixture was stirred at 215°C for 5 hours. The mixture was then gradually heated to 230°C under reduced pressure while continuing to stir, and maintained at that temperature for an additional 2 hours. The mixture was then air-cooled to terminate the reaction, yielding Amorphous Resin 1, an amorphous polyester. The weight-average molecular weight (Mw) and glass transition temperature (Tg) of Amorphous Resin 1 were measured, revealing that Mw was 23,500 and Tg was 55°C.

(Preparation of Amorphous Resin Dispersion 1)
The following materials were mixed and dissolved at 90°C.
Toluene 300.0 parts by mass Amorphous resin 1 100.0 parts by mass Separately, the following materials were mixed and dissolved at 90°C.
Ion-exchanged water 700.0 parts by mass Sodium dodecylbenzenesulfonate 5.0 parts by mass Sodium laurate 10.0 parts by mass

The resulting aqueous solution was mixed with the toluene solution and stirred at 7,000 rpm using an ultra-high-speed stirrer, T.K. Robomix (manufactured by Primix). The mixture was then emulsified at a pressure of 200 MPa using a high-pressure impact disperser, Nanomizer (manufactured by Yoshida Kikai Kogyo). The toluene was then removed using an evaporator, and the concentration was adjusted with ion-exchanged water to obtain an amorphous resin 1 dispersion containing 20% by mass of amorphous resin 1 microparticles.

The volume-based 50% particle size (D50) of the amorphous resin microparticles was measured and found to be 0.38 μm.

[Toner Production by Emulsion Aggregation Method]
Toners 24 to 26 were obtained in the same manner as in the production example of Toner 22, except that the amounts of Polymer A2 dispersion and Amorphous Resin Dispersion 1 added were changed as shown in Table 4. The physical properties of Toners 24 to 26 are shown in Tables 5 and 6.

<Production Example of Toner 39>
(Preparation of Polymer A3)
The following materials were placed in a reaction vessel equipped with a reflux condenser, a stirrer, a thermometer, and a nitrogen inlet tube under a nitrogen atmosphere.
Toluene, dodecanethiol, monomer composition (the monomer composition is a mixture of the following behenyl acrylate and acrylic acid in the ratio shown below.
Behenyl acrylate (monomer (a)) 91.5 parts by mass, acrylic acid 8.5 parts by mass, azoisobutyronitrile (AIBN) 0.75 parts by mass)

The reactor was heated to 70°C while stirring at 200 rpm, and a polymerization reaction was carried out for 16 hours, yielding a solution in which the monomer composition polymer was dissolved in toluene. The resulting solution was then cooled to 25°C, and then poured into 1,000.0 parts of methanol while stirring, causing the methanol-insoluble matter to precipitate. The resulting methanol-insoluble matter was filtered off, washed with methanol, and vacuum-dried at 40°C for 24 hours to yield Polymer A3.

(Preparation of Polymer A3 Dispersion)
Polymer A3 30 parts by mass Sodium dodecylbenzenesulfonate 1.5 parts by mass Ion-exchanged water 150 parts by mass

The above materials were weighed, mixed, heated to 90°C, and stirred at 8,000 rpm using an emulsifier (Ultra Turrax T-50, manufactured by IKA) to prepare a polymer A3 dispersion. The 50% particle size (D50) based on volume distribution of the polymer A3 dispersion was measured and found to be 0.30 μm.

<Preparation of amorphous resin 2>
The following materials were placed in a heated and dried two-necked flask while introducing nitrogen.
Polyoxyethylene (2,0)-2,2-bis(4-hydroxyphenyl)propane 19.0 parts by mass Polyoxypropylene (2,2)-2,2-bis(4-hydroxyphenyl)propane 51.0 parts by mass Terephthalic acid 23.0 parts by mass n-Dodecenylsuccinic acid 4.5 parts by mass Isophthalic acid 3.0 parts by mass Dibutyltin oxide 0.02 parts by mass

After replacing the atmosphere in the system with nitrogen, the temperature was raised and the reaction was carried out at 150-230°C for approximately 12 hours. The pressure was then gradually reduced to 210-250°C, yielding Amorphous Resin 2. The weight-average molecular weight (Mw) and glass transition temperature (Tg) of the resulting Amorphous Resin 2 were measured, revealing that Mw was 15,400 and Tg was 65°C.

(Preparation of Amorphous Resin 2 Dispersion)
Amorphous resin 2: 30 parts by mass Ethyl acetate: 100 parts by mass The above materials were weighed and mixed to dissolve the amorphous resin 2. Furthermore, the following materials were added.
1.5 parts by mass of sodium dodecylbenzenesulfonate 150g of ion-exchanged water

The mixture was heated to 60°C and stirred at 8,000 rpm using an emulsifier (Ultra Turrax T-50, manufactured by IKA), and then the ethyl acetate was evaporated to prepare an amorphous resin 2 dispersion. The 50% particle size (D50) based on volume distribution of the amorphous resin 2 dispersion was measured and found to be 0.18 μm.

(Preparation of Colorant Dispersion 3)
Colorant (Pigment Blue 15:3) 50 parts by weight Anionic surfactant Neogen SC (Dai-ichi Kogyo Seiyaku) 5.0 parts by weight Ion-exchanged water 200.0 parts by weight

The above materials were mixed, dissolved, and dispersed for 10 minutes using a homogenizer (IKA Ultra Turrax) to obtain colorant dispersion 3 with a median particle size of 175 nm and a solids content of 22.5 parts by mass.

(Preparation of Wax Dispersion 3)
Wax 7 25.0 parts by mass Anionic surfactant Neogen SC (Dai-ichi Kogyo Seiyaku) 5.0 parts by mass Ion-exchanged water 200.0 parts by mass

The above materials were mixed and heated to 97°C, and then dispersed using a homogenizer (Ultra Turrax T50, manufactured by IKA). The mixture was then dispersed ²⁰ times using a Gaulin homogenizer (manufactured by Meiwa Shoji) at 105°C and 550 kg/cm² to obtain Wax Dispersion Liquid 3. The 50% particle size (D50) based on volume distribution of Wax Dispersion Liquid 3 was measured and found to be 0.20 µm.

(Preparation of Toner 39)
Amorphous resin 2 dispersion 400.0 parts by mass Polymer A3 dispersion 100.0 parts by mass Colorant dispersion 3 20.0 parts by mass Wax dispersion 3 70.0 parts by mass 10% by mass aqueous polyaluminum chloride solution (manufactured by Asada Chemical Co., Ltd.) 1.5 parts by mass

The above materials were mixed and dispersed in a round stainless steel flask using a homogenizer (IKA Ultra Turrax T50), and the contents of the flask were then heated to 45°C while stirring and held at 45°C for 30 minutes.

The temperature of the resulting contents was then gradually raised to 55°C, and aqueous sodium hydroxide solution was added to adjust the pH to 8. The temperature was then raised to 90°C, and the aggregates were allowed to coalesce over one hour. The contents were then cooled and filtered, washed with ion-exchanged water, and dried to obtain toner particles 39.

To 100.0 parts of toner particles 39, 2.0 parts of silica fine particles (hydrophobized with hexamethyldisilazane, primary particle number average particle size: 10 nm) were added as an external additive, and the mixture was mixed at 3,000 rpm for 15 minutes using an FM mixer (manufactured by Nippon Coke & Engineering Co., Ltd.) to obtain toner 39. The physical properties of toner 39 are shown in Tables 5 and 6.

*Toner 27: 7.0 parts of Wax 1 and 2.0 parts of Wax 9 Toner 28: 2.0 parts of Wax 1 and 7.0 parts of Wax 9 Toner 29: 5.0 parts of Wax 1 and 4.0 parts of Wax 9 Toner 30: 4.0 parts of Wax 1 and 5.0 parts of Wax 9 In Table 5, Wc of the ester wax means the average number of carbon atoms in the linear alkyl group contained in the ester wax.

The melting point and Mw of Polymer A in Table 5 are those of a polymer obtained by performing the same operations as in the corresponding toner production example, except that the shell resin, wax, and colorant were not added and the step of mixing using silica fine particles was not performed.

The polymers obtained in this manner were manufactured in the same manner as the resins contained in the corresponding toners, and therefore were determined to have physical properties equivalent to those of the respective polymers A contained in the toners.

Example 1
Toner 1 was evaluated as follows. The evaluation results are shown in Table 7.

<Evaluation of Low-Temperature Fixability of Toner>
To evaluate the low-temperature fixability of the toner, a modified laser beam printer (product name: LBP-7700C, manufactured by Canon Inc.) was used as the image forming apparatus. The modifications to the modified machine were that it could operate even when the fixing unit was removed, and that the fixing temperature could be freely set. The paper used to output the image was white paper (product name: Fox River Bond (90 g/m ² ), manufactured by Fox River Inc.).

First, the toner was removed from the cartridge and cleaned with an air blower. Then, 300 g of Toner 1 was filled into the cartridge. The cartridge was then left for 48 hours in an environment with a temperature of 25°C and a humidity of 40% RH, and then installed in the cyan station of the printer under these conditions, with dummy cartridges installed in the other stations. The following evaluations were conducted under the same conditions as above.

Next, using the image forming apparatus described above with the fixing unit removed, an unfixed image of an image pattern was output in which a 10 mm x 10 mm square image was transferred to nine points, which were the intersections of the lines dividing the long and short sides of the paper into four equal parts. The toner amount on the paper was 0.80 mg/ ^cm2 .

Using the removed fixing unit, the process speed was set to 250 mm/s, and the initial temperature was 90°C. The set temperature was gradually increased by 5°C increments, and the unfixed image was fixed at each temperature to obtain a fixed image. A load of 50 g/ ^cm2 was applied to the resulting fixed image, and rubbing was performed with Silbon paper (Lenz Cleaning Paper "dasper®" (Ozu Paper Co. Ltd.)). The image density was measured before and after rubbing, and the temperature at which the decrease in image density after rubbing relative to the image density before rubbing was 20% or less was defined as the fixing initiation temperature. This value was used to evaluate the low-temperature fixability of the toner. Toners with a fixing initiation temperature of 120°C or less were deemed to have achieved the effects of the present disclosure. The evaluation results are shown in Table 7.

<Evaluation of Toner Durability>
The evaluation of the toner release property was carried out using the modified image forming apparatus and paper used in the evaluation of the low-temperature fixability described above, in a normal temperature and humidity environment of a temperature of 25° C. and a humidity of 40% RH. The evaluation of the toner durability was carried out using the contamination concentration of non-image areas caused by fine powder generated by cracks and chips in the toner as an evaluation index.

First, an all-white image was printed at a process speed of 120 mm/sec onto an evaluation sheet with a sticky note attached near the bottom center. The reflectance D1 (%) of the portion of the evaluation sheet that was hidden by the sticky note and the reflectance D2 (%) of the portion that was not hidden were measured, and the difference between these was taken as the contamination density value Di (%) of the non-image area before durability testing (Di = D2 - D1 (%)). The reflectance was measured using a REFLECTOMER MODEL TC-6DS (manufactured by Tokyo Denshoku Co., Ltd.) with an amber filter attached.

Next, a horizontal line pattern with a print rate of 1% was printed on two sheets per job, with the machine pausing between jobs before the next job began. In this mode, a total of 15,000 images were output, and the evaluation machine was turned off and left for 72 hours immediately after image output was completed. After leaving it alone, the evaluation machine was turned on again, and an all-white image was output on evaluation paper with a sticky note attached near the bottom center, as described above, and the contamination density value (Dr (%)) of the non-image area after durability testing was calculated.

(Dr - Di) was calculated from the two obtained values, and this value was used to evaluate the durability of the toner. The evaluation results are shown in Table 7. A (Dr - Di) value of less than 4.0% was determined to be one in which the effects of the present disclosure were achieved.

<Evaluation of Toner Release Properties>
The toner release properties were evaluated using a modified image forming apparatus used in the above evaluation of low-temperature fixability, and white paper (product name: GF-500 (A4, basis weight 64.0 g/m ² , Canon Marketing Japan Inc.) was used as the paper. In addition, the same procedure as above was used after filling 300 g of Toner 1 into a cartridge.

Using the modified printer with the fixing unit removed, an unfixed image was printed 1 mm from the leading edge of the evaluation paper, 100 mm wide in the paper feed direction and 200 mm wide in the direction perpendicular to the paper feed direction. The paper feed direction was portrait, and the toner amount of the unfixed image was 0.8 mg/ ^cm² .

Then, using the removed fixing unit, the temperature was increased by six points in 10°C increments from the fixing start temperature in the above-mentioned low-temperature fixing evaluation, and the number of temperatures at which the fixed image did not wrap around the fixing roller was measured, and the toner release properties were evaluated based on this number. The evaluation results are shown in Table 7. If there was one or more temperatures at which the fixed image did not wrap around the fixing roller, it was determined that the effects of the present disclosure had been achieved.

<Evaluation of Heat-Resistant Storage Stability of Toner>
6 g of Toner 1 was placed in a 100 mL plastic cup and left to stand for 10 days in an environment of a temperature of 50° C. and a humidity of 20% RH, and then the degree of cohesion of the left Toner 1 was measured as follows.

The measurement device used was a "Powder Tester" (manufactured by Hosokawa Micron Corporation) with a digital display vibrometer "DigiVibro MODEL 1332A" (manufactured by Showa Sokki Co., Ltd.) connected to the side of the vibration table. A sieve with a mesh size of 38 μm (400 mesh), a sieve with a mesh size of 75 μm (200 mesh), and a sieve with a mesh size of 150 μm (100 mesh) were placed on top of each other on the vibration table of the powder tester from the bottom up. Measurements were carried out in an environment of 23°C and 60% RH according to the following procedure.
(1) The vibration amplitude of the vibration table was adjusted in advance so that the displacement value on the digital display vibrometer was 0.60 mm (peak-to-peak).
(2) The toner that had been left for 10 days as described above was then left for 24 hours in an environment of 23° C. and 60% RH, and 5 g of the toner was weighed out and gently placed on the top sieve with 150 μm openings.
(3) After vibrating the sieves for 15 seconds, the mass of the toner remaining on each sieve was measured, and the degree of cohesion (%) was calculated using the following formula. The evaluation results are shown in Table 7. A degree of cohesion of 30% or less was determined to be one in which the effects of the present disclosure were obtained.
Cohesion degree (%)={(mass (g) of sample on sieve with 150 μm opening)/5 (g)}×100
+ {(mass of sample on sieve with 75 μm openings (g))/5 (g)} × 100 × 0.6
+ {(mass of sample on sieve with 38 μm openings (g))/5 (g)} × 100 × 0.2

Claims (6)

A toner having toner particles containing a resin component and a wax,
the resin component is a vinyl polymer A having a monomer unit A represented by the following formula (A),
the wax is composed solely of esters of hexahydric alcohol and aliphatic monocarboxylic acid,
The wax contained in the toner particles includes a wax that forms a eutectic structure with the resin component and a single wax that does not form a eutectic structure,
When a backscattered electron image of the cross section of the toner particle is obtained by observing the cross section of the toner particle with a scanning transmission electron microscope, and the brightness of each pixel constituting the backscattered electron image is divided into 256 gradations from a brightness of 0 at the darkest part to a brightness of 255 at the brightest part, a brightness histogram is obtained in which the horizontal axis is brightness and the vertical axis is the number of pixels.
When the total number of pixels with brightness 0 to 9 is C and the total number of pixels with brightness 0 to 245 is A,
The C and the A satisfy the following formula (1),
0.002 ≦C/A≦0.250 (1)
The luminance indicating the maximum number P of pixels in the range of luminance 10 to luminance 245 of the histogram is defined as luminance X,
The luminance at which the number of pixels falls below 20% of P for the first time from the luminance X toward the luminance 245 is defined as luminance M,
When the number of pixels falls below 20% of P for the first time from the brightness X to the brightness 10, the brightness is defined as N.
A toner characterized in that the value of luminance M-luminance N is 120 to 235.

(In formula (A), ^R1 represents H or _CH3 , and ^R2 represents an alkyl group having 18 to 36 carbon atoms.) The C and A satisfy the following formula (2): 0.00 2 ≦C/A≦0.100 (2)
The toner according to claim 1 . The toner according to claim 1 or 2, wherein the content of the monomer unit A in the vinyl polymer A is 20.0 to 80.0% by mass. 4. The toner according to claim 1 , wherein the ratio of the mass of the wax to the mass of the resin component is 1.0 to 25.0% by mass. 5. The toner according to claim 1 , wherein the wax has a molecular weight of 1,000 to 3,000. A method for producing the toner according to any one of claims 1 to 5 ,
The manufacturing method comprises:
a step of obtaining toner base particles containing the wax and the resin component; and, when the melting point of the wax is TmW and the melting point of the vinyl polymer A is TmA,
a step of subjecting the toner base particles to a heat treatment in a temperature range of TmA to TmW for 30 minutes or more to obtain toner particles;
A toner manufacturing method comprising: