JP7589451B2 - Electrophotographic developer, replenishment developer, image forming apparatus, process cartridge, and image forming method - Google Patents

Description

The present invention relates to an electrophotographic developer, a replenishment developer, an image forming apparatus, a process cartridge, and an image forming method.

In electrophotographic image formation, an electrostatic latent image is formed on an electrostatic latent image carrier such as a photoconductive material, and a toner image is formed by attaching charged toner to this electrostatic latent image. The toner image is then transferred to a recording medium and fixed to obtain an output image. In recent years, coupled with the increasing printing speed, there is a strong demand for carriers with the ability to quickly impart a charge to the toner.

As a result, with conventional charging capabilities, the toner replenished to the developer is not sufficiently frictionally charged with the carrier, resulting in problems such as toner scattering, in which the toner accumulates outside the developing unit, and background scumming, in which the toner is developed into blank areas.
For this reason, there is an increased demand for controlling the charge amount of toner to a constant level, and conventional carriers are unable to satisfy the required characteristics.

In addition, in order to improve image quality, such as the occurrence of fogged images over time, it has been proposed to use surface-treated metal oxide particles as an external additive to the toner (see, for example, Patent Document 1).

On the other hand, various attempts have been made to improve the durability of carriers. For example, Patent Documents 2 and 6 describe a method of coating the carrier with a suitable resin material. Patent Documents 3 to 5 also describe a method of adding various additives to the resin layer.

The object of the present invention is to provide an electrophotographic developer that prevents the occurrence of fogged images over time during long-term printing, has excellent long-term charging stability, and is excellent in the toner-spent properties of the carrier and the wear resistance (abrasion and peeling) of the resin layer.

The above problem is solved by the following configuration 1).
1) An electrophotographic developer comprising a toner containing inorganic particles and a carrier having core particles and a resin layer covering the surfaces of the core particles,
the toner contains at least fluorine-containing alumina particles as the inorganic particles, the resin layer contains an acrylic silicone resin, and the acrylic silicone resin contains a crosslinked product of a copolymer containing at least a component A represented by the following general formula (A) and a component B represented by the following general formula (B) :
General formula (A) and general formula (B) are shown in the mode for carrying out the invention.

The present invention provides an electrophotographic developer that prevents the occurrence of fogged images over time during long-term printing, has excellent long-term charging stability, and is excellent in toner-spent properties of the carrier and wear resistance (abrasion and peeling) of the resin layer.

FIG. 2 is a diagram illustrating an example of a process cartridge of the present invention.

According to the studies of the present inventors, in an electrophotographic developer containing a toner and a carrier, image quality such as fog images that occur over time can be improved by adding fluorine-containing alumina particles to the toner as inorganic particles. However, it has been found that when such inorganic particles are used, the resin layer on the carrier surface is scraped off due to collisions between the alumina particles and between the carrier particles during long-term printing, causing an increase in charge over time, resulting in problems such as carrier adhesion and insufficient image density (ID).
On the other hand, a method of adding additives to the resin layer of the carrier to improve the abrasion resistance has been carried out, but while this method increases the durability of the carrier, it also affects the charging ability during printing, and further causes toner spent on the carrier surface, which reduces the charging ability over long-term use, making it difficult to maintain image quality.

The present invention will now be described in further detail.
It should be noted that the embodiments described below are preferred embodiments of the present invention and therefore include various technically preferable limitations. However, the scope of the present invention is not limited to these embodiments unless otherwise stated in the following description to the effect that the present invention is limited thereto.

(Developer)
The electrophotographic developer of the present invention contains a toner containing inorganic particles and a carrier having core particles and a resin layer covering the surfaces of the core particles, and is characterized in that the toner contains at least fluorine-containing alumina particles as the inorganic particles, and the resin layer contains an acrylic silicone resin.

The present invention also includes the following configurations 2) to 9) as preferred embodiments.
2) The electrophotographic developer according to 1) above, wherein the acrylic silicone resin contains a crosslinked product of a copolymer containing at least a component A represented by the following general formula (A) and a component B represented by the following general formula (B):

(In formulas (A) and (B), R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkyl group having 1 to 4 carbon atoms, R ³ represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and m represents an integer of 1 to 8. A plurality of R ² may be the same or different. X represents 10 to 90 mol %, and Y represents 90 to 10 mol %).

3) The electrophotographic developer according to 1) or 2) above, characterized in that the copolymer contains a copolymer represented by the following general formula (1):

(In formula (1), R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkyl group having 1 to 4 carbon atoms, R ³ represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and m represents an integer of 1 to 8. A plurality of R ² may be the same or different. X represents 10 to 40 mol %, Y represents 10 to 40 mol %, Z represents 30 to 80 mol %, and 60 mol %≦Y+Z≦90 mol %).

4) The electrophotographic developer according to any one of 1) to 3) above, wherein when the aluminum concentration (atomic %) and the fluorine concentration (atomic %) in the toner determined by X-ray photoelectron spectroscopy (XPS) are X1 and X2, respectively, the toner satisfies the following relational expressions (2) and (3):
2.7≦X1/X2≦5.5 Formula (2)
2.1≦X1≦3.0 Formula (3)

5) The electrophotographic developer according to any one of 1) to 4) above, wherein the toner further contains inorganic particles other than the fluorine-containing alumina particles, and the median diameter of the inorganic particles other than the fluorine-containing alumina particles is 60 nm or more and 300 nm or less.

6) A refill developer containing a carrier and a toner, the refill developer being any one of the developers described in 1) to 5) above, and characterized in that the refill developer contains 2 parts by weight or more and 50 parts by weight or less of the toner per 1 part by weight of the carrier.

7) An image forming apparatus comprising: an electrostatic latent image carrier; a charging means for charging the electrostatic latent image carrier; an exposure means for forming an electrostatic latent image on the electrostatic latent image carrier; a developer carrier that rotates in close proximity to the electrostatic latent image carrier and carries an electrophotographic developer described in any one of 1) to 5) above; a developing device that develops the electrostatic latent image formed on the electrostatic latent image carrier using the electrophotographic developer described in any one of 1) to 5) above to form a toner image; a transfer means that transfers the toner image formed on the electrostatic latent image carrier to a recording medium; and a fixing means that fixes the toner image transferred to the recording medium.

8) A process cartridge comprising: an electrostatic latent image carrier; a charging member for charging the surface of the electrostatic latent image carrier; a developing unit for developing an electrostatic latent image formed on the electrostatic latent image carrier by using the electrophotographic developer described in any one of 1) to 5) above; and a cleaning member for cleaning the electrostatic latent image carrier.
9) An image forming method comprising the steps of: forming an electrostatic latent image on an electrostatic latent image carrier; developing the electrostatic latent image formed on the electrostatic latent image carrier with the electrophotographic developer described in any one of 1) to 5) above to form a toner image; transferring the toner image formed on the electrostatic latent image carrier to a recording medium; and fixing the toner image transferred to the recording medium.

As described above, in an electrophotographic developer containing a toner and a carrier, the image quality, such as fogged images over time, can be improved by adding fluorine-containing alumina particles as inorganic particles to the toner. However, alumina particles are highly abrasive, and when such inorganic particles are used, the resin layer on the carrier surface is scraped off by collisions between the alumina particles and the carriers during long-term printing, causing the charge to increase over time, resulting in carrier adhesion and insufficient image density (ID). In the present invention, by incorporating an acrylic silicone resin into the resin layer that coats the carrier, it is possible to suppress the occurrence of fogged images over long-term printing, improve the abrasion resistance and toner spent properties of the carrier, and stabilize the charge.

(Resin Layer)
The acrylic silicone resin is not particularly limited in terms of its material, but preferably contains a crosslinked product of a copolymer containing a component A represented by the following general formula (A) and a component B represented by the following general formula (B). The crosslinked product is obtained by heat-treating the copolymer. The content of the crosslinked product in the resin layer is preferably 25 to 65% by mass, more preferably 30 to 50% by mass.

In formula (A), ^R1 represents a hydrogen atom or a methyl group. ^R2 represents an alkyl group having 1 to 4 carbon atoms, and examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group. m represents an integer of 1 to 8, and examples of the alkylene group represented by ( _CH2 ) _m include a methylene group, an ethylene group, a propylene group, and a butylene group. Multiple ^R2s may be the same or different.

In component A, X is 10 to 90 mol%, preferably 10 to 40 mol%, and more preferably 20 to 30 mol%. Component A has an atomic group, tris(trimethylsiloxy)silane, which has many methyl groups in the side chain, and as the ratio of component A to the entire resin increases, the surface energy decreases and adhesion of the resin components, wax components, etc. of the toner decreases. By having component A at 10 mol% or more, the desired effect is obtained and adhesion of the toner components is prevented. Also, by having component A at 90 mol% or less, the amount of component B is appropriate, sufficient crosslinking proceeds, and toughness is increased, as well as the adhesion between the core particles and the resin layer and the durability of the resin layer are improved.

An example of the monomer A that produces such an A component is a tris(trialkylsiloxy)silane compound represented by the following formula: In the formula, Me is a methyl group, Et is an ethyl group, and Pr is a propyl group.
CH ₂ =CMe-COO-C ₃ H ₆ -Si(OSiMe ₃ ) ₃
CH ₂ =CH-COO-C ₃ H ₆ -Si(OSiMe ₃ ) ₃
CH ₂ =CMe-COO-C ₄ H ₈ -Si(OSiMe ₃ ) ₃
CH ₂ =CMe-COO-C ₃ H ₆ -Si(OSiEt ₃ ) ₃
CH ₂ =CH-COO-C ₃ H ₆ -Si(OSiEt ₃ ) ₃
CH ₂ =CMe-COO-C ₄ H ₈ -Si(OSiEt ₃ ) ₃
CH ₂ =CMe-COO-C ₃ H ₆ -Si(OSiPr ₃ ) ₃
CH ₂ =CH-COO-C ₃ H ₆ -Si(OSiPr ₃ ) ₃
CH ₂ =CMe-COO-C ₄ H ₈ -Si(OSiPr ₃ ) ₃
The method for producing the monomer A for component A is not particularly limited, but it can be obtained by a method of reacting tris(trialkylsiloxy)silane with allyl acrylate or allyl methacrylate in the presence of a platinum catalyst, or a method described in JP-A-11-217389 of reacting methacryloxyalkyltrialkoxysilane with hexaalkyldisiloxane in the presence of a carboxylic acid and an acid catalyst, etc. The silane compounds may be used alone or in combination of two or more.

Component B is a cross-linking component and is represented by the following general formula (B).

In formula (B), R ¹ , R ² and m are the same as those explained in formula (A). ^{R 3} represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and examples of the alkyl group include those similar to those described above. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group.
In the B component, Y is 10 to 90 mol%, preferably 10 to 80 mol%, and more preferably 15 to 70 mol%. When the B component is 10 mol% or more, sufficient toughness is obtained. On the other hand, when the B component is 90 mol% or less, the resin layer is prevented from becoming hard and brittle, and film scraping is prevented. In addition, environmental characteristics are improved. Furthermore, the hydrolyzed crosslinking components do not remain in large numbers as silanol groups, and environmental characteristics (humidity dependency) are also improved.

The monomer B component (including the precursor) which produces such a B component is a radically polymerizable difunctional (when R ³ is an alkyl group) or trifunctional (when R ³ is also an alkoxy group) silane compound.
Examples of such monomer B component include 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltri(isopropoxy)silane, 3-acryloxypropyltri(isopropoxy)silane, etc. These compounds may be used alone or in combination of two or more.

For example, a technology for enhancing durability by crosslinking a coating is described in Japanese Patent No. 3691115. The carrier described in Japanese Patent No. 3691115 is a carrier for developing electrostatic images, characterized in that the surface of the magnetic particles is coated with a thermosetting resin in which a copolymer of an organopolysiloxane having at least a vinyl group at the end and a radical copolymerizable monomer having at least one functional group selected from the group consisting of a hydroxyl group, an amino group, an amide group, and an imide group is crosslinked with an isocyanate compound. However, the coating does not currently have sufficient durability against peeling and scraping.

The reason for this is not fully clear, but in the case of a thermosetting resin in which a copolymer is crosslinked with an isocyanate compound, as can be seen from the structural formula, there are few functional groups (active hydrogen-containing groups such as amino groups, hydroxyl groups, carboxyl groups, mercapto groups, etc.) per unit mass that react (crosslink) with the isocyanate compound in the copolymer resin, and a dense two-dimensional or three-dimensional crosslinked structure cannot be formed at the crosslinking points. Therefore, when used for a long period of time, the coating is likely to peel off or be scraped off (the coating has low abrasion resistance), and it is presumed that sufficient durability is not obtained.
When the coating peels off or is scraped off, the carrier resistance decreases, causing changes in image quality and carrier adhesion.Furthermore, peeling or scraping of the coating reduces the fluidity of the developer, causing a decrease in the amount of developer pumped up, resulting in a decrease in image density, background scumming due to an increase in toner concentration (TC), and toner scattering.

In the present invention, a copolymer having a large number of bifunctional or trifunctional crosslinkable functional groups (points) per unit mass of resin (2 to 3 times more per unit mass) is used, and this copolymer is further crosslinked by condensation polymerization and contained in the resin layer, so that the coating is extremely tough and difficult to scrape, and it is believed that high durability is achieved.
Furthermore, it is presumed that the crosslinking by the siloxane bond in the present invention has a larger bond energy and is more stable against heat stress than the crosslinking by an isocyanate compound, and therefore the stability over time of the resin layer is maintained.

In the present invention, in order to impart sufficient flexibility and improve the adhesion between the core particles and the resin layer, the resin layer can further contain a component C represented by the following general formula (C). That is, the resin layer can contain a copolymer represented by the following general formula (1).

In the formula, R ¹ represents a hydrogen atom or a methyl group. R ² represents an alkyl group having 1 to 4 carbon atoms, and examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group. R ³ represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and examples of the alkyl group include those described above. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. m represents an integer of 1 to 8, and examples of the alkylene group represented by (CH ₂ )m include a methylene group, an ethylene group, a propylene group, and a butylene group. A plurality of R ^1s and R ^2s may be the same or different from each other.

In the copolymer represented by the general formula (1), X is 10 to 40 mol%, preferably 20 to 30 mol%. Y is 10 to 40 mol%, preferably 15 to 25 mol%. Z is 30 to 80 mol%, preferably 35 to 75 mol%. The sum of Y and Z is 60 mol%≦Y+Z≦90 mol%, preferably 70 mol%<Y+Z<85 mol%. By making the C component 80 mol% or less, either X or Y is 10 mol% or more, so that the resin layer can have both water repellency, hardness, and flexibility (film abrasion resistance).

Monomer that produces component C Component C is a radical polymerizable (meth)acrylic compound (monomer) having an acryloyl group or a methacryloyl group.
As such a (meth)acrylic compound, acrylic acid esters and methacrylic acid esters are preferred, and specific examples thereof include methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, butyl methacrylate, butyl acrylate, 2-(dimethylamino)ethyl methacrylate, 2-(dimethylamino)ethyl acrylate, 3-(dimethylamino)propyl methacrylate, 3-(dimethylamino)propyl acrylate, 2-(diethylamino)ethyl methacrylate, and 2-(diethylamino)ethyl acrylate.
Among these, alkyl methacrylates are preferred, and methyl methacrylate is particularly preferred. These compounds may be used alone or in combination of two or more.

The copolymer in the present invention is a (meth)acrylic copolymer obtained by radical copolymerization of each monomer including component A and component B, and in addition to having many crosslinkable functional groups per unit mass of resin, component B, which is a crosslinking component, is crosslinked by condensation polymerization through heat treatment. Therefore, it is believed that the resin layer is extremely tough and difficult to scrape, thereby achieving high durability.
Furthermore, it is presumed that the crosslinking by the siloxane bond in the present invention has a larger bond energy and is more stable against heat stress than the crosslinking by an isocyanate compound, and therefore the stability over time of the resin layer is maintained.

In the present invention, the resin layer composition for forming the resin layer preferably contains a silicone resin having a silanol group and/or a functional group capable of generating a silanol group by hydrolysis.
Silicone resins having silanol groups and/or functional groups capable of generating silanol groups by hydrolysis (e.g., negative groups such as alkoxy groups and halogeno groups bonded to Si atoms) can be condensed with the component B of the copolymer directly or with the component B in a state in which it has been converted to a silanol group. The inclusion of a silicone resin component in the copolymer further improves the toner spent property.

In the present invention, the silicone resin having a silanol group and/or a functional group capable of generating a silanol group by hydrolysis used in forming the resin layer preferably contains at least one repeating unit represented by the following general formula (4):

In general formula (4), A ¹ represents a hydrogen atom, a halogen atom, a hydroxyl group, a methoxy group, an alkyl group having 1 to 4 carbon atoms, or an aryl group, and A ² represents an alkylene group or an arylene group having 1 to 4 carbon atoms.

Examples of halogen atoms include fluorine, chlorine, bromine, and iodine. Examples of alkyl groups having 1 to 4 carbon atoms include methyl, ethyl, propyl, isopropyl, and butyl groups. Examples of aryl groups include phenyl and tolyl groups. Examples of alkylene groups having 1 to 4 carbon atoms include methylene, ethylene, propylene, and butylene groups. Examples of arylene groups include phenylene and naphthylene groups.

The aryl group has 6 to 20 carbon atoms, preferably 6 to 14. The aryl group includes aryl groups derived from benzene (phenyl groups), as well as aryl groups derived from condensed polycyclic aromatic hydrocarbons such as naphthalene, phenanthrene, and anthracene, and aryl groups derived from chain polycyclic aromatic hydrocarbons such as biphenyl and terphenyl. The aryl group may be substituted with various substituents.

The number of carbon atoms in the arylene group is 6 to 20, preferably 6 to 14. Examples of the arylene group include arylene groups derived from benzene (phenylene groups), as well as arylene groups derived from condensed polycyclic aromatic hydrocarbons such as naphthalene, phenanthrene, and anthracene, and arylene groups derived from chain polycyclic aromatic hydrocarbons such as biphenyl and terphenyl. The arylene group may be substituted with various substituents.

Commercially available silicone resins that can be used in the present invention include, but are not limited to, KR251, KR271, KR272, KR282, KR252, KR255, KR152, KR155, KR211, KR216, and KR213 (all manufactured by Shin-Etsu Silicones), AY42-170, SR2510, SR2400, SR2406, SR2410, SR2405, and SR2411 (manufactured by Dow Corning Toray Co., Ltd.).

As mentioned above, various silicone resins can be used, but methyl silicone resins are particularly preferred due to their low toner spent property and small environmental fluctuations in charge amount.

The weight average molecular weight of the silicone resin is about 1,000 to 100,000, preferably about 1,000 to 30,000. By using a resin with a molecular weight of 100,000 or less, the increase in viscosity of the coating liquid during coating is suppressed, sufficient uniformity of the coating film is obtained, and the density of the resin layer after curing is also sufficiently increased. By using a molecular weight of 1,000 or more, problems such as the resin layer becoming brittle after curing are unlikely to occur.
The content of the silicone resin is usually about 5 to 80 parts by mass, preferably 10 to 60 parts by mass, based on 100 parts by mass of the copolymer. When the content of the silicone resin is 5 parts by mass or more, spent resistance is improved, and when it is 80 parts by mass or less, the toughness of the resin layer is increased and scraping of the film is prevented.

In the present invention, a silane coupling agent can be used to improve the dispersibility of the conductive fine particles and to adjust the toner charge amount.
Examples of the silane coupling agent include, but are not limited to, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, r-methacryloxypropyltrimethoxysilane, N-β-(N-vinylbenzylaminoethyl)-r-aminopropyltrimethoxysilane hydrochloride, γ-glycidoxypropyltrimethoxysilane, r-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, hexamethyldisilazane, γ-anilino Propyltrimethoxysilane, vinyltrimethoxysilane, octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride, γ-chloropropylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, allyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, dimethyldiethoxysilane, 1,3-divinyltetramethyldisilazane, methacryloxyethyldimethyl(3-trimethoxysilylpropyl)ammonium chloride, and the like can be mentioned, and two or more of them may be used in combination.

Commercially available silane coupling agents include AY43-059, SR6020, SZ6023, SH6026, SZ6032, SZ6050, AY43-310M, SZ6030, SH6040, AY43-026, AY43-031, sh6062, Z-6911, sz6300, sz6075, sz6079, sz6083, sz6070, sz6072, Z-6721, AY43-004, Z-6 187, AY43-021, AY43-043, AY43-040, AY43-047, Z-6265, AY43-204M, AY43-048, Z-6403, AY43-206M, AY43-206E, Z6341, AY43-210MC, AY43-083, AY43-101, AY43-013, AY43-158E, Z-6920, Z-6940 (manufactured by Toray Silicone Co., Ltd.), etc.

The amount of silane coupling agent added is preferably 0.1 to 10% by mass relative to the silicone resin. When the amount of silane coupling agent added is 0.1% by mass or more, the adhesion between the core particles or conductive fine particles and the silicone resin is improved, preventing the resin layer from falling off during long periods of printing, and when the amount is 10% by mass or less, toner filming during long periods of printing is suppressed.

The resin layer composition according to the present invention may also contain resins other than the silicone resin having the silanol group and/or hydrolyzable functional group. Examples of such resins include, but are not limited to, acrylic resins, amino resins, polyvinyl resins, polystyrene resins, halogenated olefin resins, polyester resins, polycarbonate resins, polyethylene resins, polyvinyl fluoride resins, polyvinylidene fluoride resins, polytrifluoroethylene resins, polyhexafluoropropylene resins, copolymers of vinylidene fluoride and vinyl fluoride, fluoro terpolymers such as terpolymers of tetrafluoroethylene, vinylidene fluoride and non-fluorinated monomers, silicone resins that do not have silanol groups or hydrolyzable functional groups, etc. Two or more of these may be used in combination. Among them, acrylic resins are preferred because of their strong adhesion to the core particles and conductive fine particles and low brittleness.

The acrylic resin preferably has a glass transition point of 20 to 100°C, more preferably 25 to 80°C. Such acrylic resin has a suitable elasticity, so that when a strong impact is applied to the resin layer due to friction between the toner and carrier or between carriers when the developer is triboelectrically charged, the impact can be absorbed, and deterioration of the resin layer and conductive fine particles can be prevented.

Further, it is more preferable that the resin layer contains a crosslinked product of an acrylic resin and an amino resin, which can suppress fusion between the resin layers while maintaining an appropriate elasticity.
The amino resin is not particularly limited, but is preferably a melamine resin or a benzoguanamine resin because it can improve the chargeability of the carrier. In addition, when it is necessary to appropriately control the chargeability of the carrier, the melamine resin and/or the benzoguanamine resin may be used in combination with other amino resins.

As the acrylic resin that can be crosslinked with the amino resin, one having a hydroxyl group and/or a carboxyl group is preferable, and one having a hydroxyl group is more preferable. This can further improve the adhesion with the core particles and the conductive fine particles, and can also improve the dispersion stability of the conductive fine particles. In this case, the acrylic resin preferably has a hydroxyl value of 10 mgKOH/g or more, and more preferably 20 mgKOH/g or more.

Titanium-based catalysts, tin-based catalysts, zirconium-based catalysts and aluminum-based catalysts can be used to promote the condensation reaction of the crosslinking component B. Among these catalysts, titanium-based catalysts that provide excellent results are preferred, and titanium alkoxides and titanium chelates are particularly preferred.
This is believed to be because the catalyst is highly effective in promoting the condensation reaction of the silanol groups derived from component B and is not easily deactivated. An example of a titanium alkoxide catalyst is titanium diisopropoxybis(ethylacetoacetate) represented by the following formula (5), and an example of a titanium chelate catalyst is titanium diisopropoxybis(triethanolamine) represented by the following formula (6).

Ti(Oi-C ₃ H ₇ ) ₂ (C ₆ H ₉ O ₃ ) ₂ (5)
Ti(O-i-C ₃ H ₇ ) ₂ (C ₆ H ₁₄ N) ₂ (6)

The resin layer can be formed using a resin layer composition containing a copolymer containing the A component and the B component, a titanium diisopropoxybis(ethylacetoacetate) catalyst, and, if necessary, a resin other than the copolymer containing the A component and the B component, and a solvent.
Specifically, the resin layer may be formed by condensing the silanol groups while coating the core particles with the resin layer composition, or the resin layer may be formed by condensing the silanol groups after coating the core particles with the resin layer composition.
The method of condensing the silanol groups while coating the core particles with the resin layer composition is not particularly limited, but examples thereof include a method of coating the core particles with the resin layer composition while applying heat, light, etc. Furthermore, the method of condensing the silanol groups after coating the core particles with the resin layer composition is not particularly limited, but examples thereof include a method of coating the core particles with the resin layer composition and then performing a heat treatment.

Furthermore, resins with large molecular weights usually have very high viscosities, and when applied to small core particles, they are prone to particle aggregation and non-uniformity of the resin layer, making it extremely difficult to produce a coated carrier.
Therefore, the copolymer according to the present invention preferably has a weight average molecular weight of 5,000 to 100,000, more preferably 10,000 to 70,000, and even more preferably 30,000 to 40,000. When the weight average molecular weight is 5,000 or more, the strength of the resin layer is improved, and when it is 100,000 or less, an increase in the liquid viscosity of the resin layer composition is suppressed, and the carrier manufacturability is improved.

In the present invention, after the core particles are coated with the resin layer composition, the core particles are heat-treated at a temperature lower than the Curie point of the core particles used, preferably at a temperature of 100 to 350° C., to promote the crosslinking reaction by condensation.
When the heat treatment temperature is 100° C. or higher, the crosslinking reaction due to condensation proceeds, and sufficient strength of the resin layer is obtained, whereas when the heat treatment temperature is 350° C. or lower, carbonization of the copolymer is prevented, and the resin layer is less likely to be scraped off.

(Inorganic particles)
In the present invention, the resin layer may contain inorganic particles, whereby the inorganic particles are exposed during long-term printing, and the scraping and peeling of the resin layer due to the stress of stirring can be significantly suppressed by the spacer effect.

The inorganic particles are not particularly limited in terms of material, but when a negatively charged toner is used, if a material having positive charging properties is used for the inorganic particles, the charging ability will be stable over a long period of time. Particularly preferred materials include barium sulfate, zinc oxide, magnesium oxide, magnesium hydroxide, and hydrotalcite. Barium sulfate is particularly preferable because it has a high charging ability for negatively charged toner, is white, and has little effect on the color of the toner even when it is detached from the coating resin.
The content of the inorganic particles in the resin layer is preferably 10 to 70% by mass relative to the resin.

The thickness of the resin layer is preferably 0.05 μm to 4 μm, and more preferably 0.2 μm to 1 μm.

(Core particles)
In the present invention, the core particles are not particularly limited as long as they are magnetic, and examples thereof include ferromagnetic metals such as iron and cobalt, iron oxides such as magnetite, hematite, and ferrite, various alloys and compounds, and resin particles in which these magnetic materials are dispersed in resin. Among these, Mn-based ferrite, Mn-Mg-based ferrite, Mn-Mg-Sr ferrite, etc. are preferred from the viewpoint of environmental friendliness.

(toner)
The toner of the present invention contains at least fluorine-containing alumina particles as inorganic particles, which reduces the difference between the amount of triboelectric charge at high temperature and high humidity and at low temperature and low humidity, improving the environmental stability of charging.

In addition, when the aluminum concentration (atomic %) in the toner determined by X-ray photoelectron spectroscopy (XPS) is X1 and the fluorine concentration (atomic %) is X2, it is preferable that both of the following relational expressions (2) and (3) are satisfied.
2.7≦X1/X2≦5.5 Formula (2)
2.1≦X1≦3.0 Formula (3)

In the prior art, fluorine-containing alumina particles are sometimes used as an external additive for a toner, but the present inventors have found through their research that it is preferable to specify the relative amounts of fluorine used in the alumina powder and the alumina surface treatment, and the state of the fluorine in the toner, as described below, and that the amount of fluorine in the alumina and the alumina surface layer in the toner, particularly the amount of fluorine in the alumina and the alumina surface layer present in a region up to a depth of about 5 nm in the outermost layer of the toner, greatly affects the ability to charge in a short period of time, that is, the so-called charge rise property, when charging due to friction with a carrier, particularly a carrier whose charging ability has deteriorated over time.
That is, it is preferable that the aluminum concentration X1 and the fluorine concentration X2 satisfy the formulas (2) and (3).

By setting X1 of the aluminum concentration in formula (3) to 2.1 or more, the saturated charge value of the toner in a low-temperature, low-humidity environment becomes appropriate, and the quality problem of thin image density (ID) can be prevented. On the other hand, by setting X1 to 3.0 or less, fluorine derived from alumina is less likely to be spent (adhered) to the carrier over time, the charging ability of the carrier is improved, the charge rise property of the toner in a low-temperature, low-humidity environment is improved, and the amount of weakly or reversely charged toner particles is suppressed, thereby preventing the so-called fog image problem.
By setting the ratio X1/X2 of the aluminum concentration X1 and the fluorine concentration X2 in formula (2) to 2.7 or more, fluorine derived from alumina is less likely to be spent (adhered) to the carrier over time, the charging ability of the carrier is improved, the charge rise property of the toner in a low-temperature, low-humidity environment is improved, and the amount of weakly or reversely charged toner particles is suppressed, thereby preventing the so-called fog image problem. On the other hand, by setting X1/X2 to 5.5 or less, the amount of fluorine contributing to the toner charge rise becomes appropriate, the charge rise property of the toner in a low-temperature, low-humidity environment is improved, and the amount of weakly or reversely charged toner particles is suppressed, thereby preventing the so-called fog image problem.

Furthermore, it is more preferable that the ranges of X1 and X1/X2 satisfy both of the relationships of the following formulas (7) and (8), because image quality issues such as fogging caused by insufficient charge build-up due to friction between the toner and carrier over time are further improved.
2.8≦X1/X2≦5.2 Formula (7)
2.1≦X1≦2.9 Formula (8)

The X-ray photoelectron spectroscopy (XPS) method for the toner is carried out under the following measurement conditions.
Analytical equipment: AXIS-ULTRA (Shimadzu Corporation)
X-ray: 15kV, 9mA, Hybrid
Neutralization gun: 2.0A (F-Current), 1.3V (F-Bias), 1.8V (C-Balance)
Step: 0.1eV(Narrow), 2.0eV(Wide)
PassE: 20eV(Narrow), 160eV(Wide)
Relative sensitivity coefficient: Use the relative sensitivity coefficient of CasaXPS

The method for preparing the fluorine-containing alumina particles used in the present invention is not particularly limited, but may be, for example, a method of coating alumina with a fluorine-containing silane coupling agent. The fluorine-containing silane coupling agent is not particularly limited, but may include trifluoropropyltrimethoxysilane, triethoxytridecafluoro-n-octylsilane, triethoxyperfluorohexylsilane, triethoxyperfluorodecylsilane, trimethoxyperfluorodecylsilane, trimethoxyperfluorohexylsilane, and heptadecafluorodecyltrimethoxysilane.
The amount of the fluorine-containing silane coupling agent attached to the alumina is, for example, 1 to 90% by mass, and preferably 2 to 80% by mass.

The content of fluorine-containing alumina particles in the toner is preferably 0.2 to 4.0 parts by mass, and more preferably 0.3 to 2.0 parts by mass, per 100 parts by mass of the toner.

The toner in the present invention may further contain inorganic particles other than the fluorine-containing alumina particles.
Examples of such inorganic particles include silica, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, pengallo, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.
The inorganic particles may be surface-treated to increase the hydrophobicity of the surface and prevent deterioration of flow characteristics and charging characteristics even under high humidity.Preferable surface treatment agents include, for example, fluorine-containing silane coupling agents, silylating agents, silane coupling agents having a fluorinated alkyl group, organic titanate coupling agents, aluminum coupling agents, silicone oils, modified silicone oils, etc.

Furthermore, the amount of inorganic particles other than the fluorine-containing alumina particles added is 0.4 to 4.0 parts by weight, more preferably 1.0 to 2.2 parts by weight, per 100 parts by weight of toner. Adding an amount of more than 0.4 parts by weight can sufficiently improve the fluidity and cohesiveness of the toner, and does not cause problems such as a decrease in the image quality of halftone images or white spots in images due to toner cohesion. On the other hand, adding an amount of less than 4.0 parts by weight does not cause problems such as an increase in the minimum fixing temperature and poor low-temperature fixing ability.

The median diameter of the inorganic particles other than the fluorine-containing alumina particles is preferably 60 nm or more and 300 nm or less.
When the median diameter is 60 nm or more, the spacer effect of the large particle size inorganic particles acts on the outermost layer of the toner, and the fluorine-containing alumina is embedded in the toner base particles due to stirring stress in the image forming device, which can prevent the problem of low image density over time and the occurrence of fogged images.
In addition, by making the median diameter 300 nm or less, the large-diameter inorganic particles are tightly externally added to the outermost surface layer of the toner, and the large-diameter inorganic particles are detached from the toner surface layer due to stirring stress, weakening the spacer effect, and the fluorine-containing alumina is embedded in the toner base particles due to stirring stress in the image forming device, which can prevent problems such as low image density over time and the occurrence of fogged images.

The median diameter is measured under the following conditions.
(1) Place 0.1 g of a sample in a glass bottle, add 20 g of methanol, and stir.
(2) Disperse the mixture in an ultrasonic dispersing device for 10 minutes to prepare a measurement sample.
(3) The sample from (2) is measured using a laser diffraction/scattering particle size distribution analyzer to determine the median diameter.

The toner in the present invention preferably contains at least one of carnauba wax, rice wax and ester wax as a wax component.
Carnauba wax is a natural wax obtained from the leaves of the carnauba palm, and in particular, a low acid value type from which free fatty acids have been removed is preferred because it can be uniformly dispersed in the binder resin.
Rice wax is a natural wax obtained by refining the sparse wax produced during the dewaxing or wintering process of refining rice bran oil extracted from rice bran.
Ester wax is synthesized by an ester reaction between a monofunctional straight-chain fatty acid and a monofunctional straight-chain alcohol.
These wax components may be used alone or in combination. The amount of the wax component added is preferably 0.5 to 20 parts by weight, more preferably 2 to 10 parts by weight, based on 100 parts by weight of the toner.
In the present invention, wax components other than those mentioned above can also be used, for example, polyolefin waxes such as polypropylene wax, polyethylene wax, etc.

As the binder resin for the toner in the present invention, all polymer resins obtained by condensation polymerization reactions of polyester, polyamide, polyester-polyamide resins, etc., or polymer resins obtained by addition polymerization reactions of styrene-acrylic, styrene-butadiene, etc. can be used.

The polyester resin used in the present invention is a polymer obtained by condensation polymerization of a polyhydric hydroxy compound and a polybasic acid. Examples of polyhydric hydroxy compounds include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, and propylene glycol, alicyclic compounds containing two hydroxyl groups such as 1,4-bis(hydroxymethyl)cyclohexane, and dihydric phenol compounds such as bisphenol A. Polyhydric hydroxy compounds also include those containing three or more hydroxyl groups.

Examples of polybasic acids include dibasic carboxylic acids such as maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, and malonic acid, as well as tribasic or higher polybasic carboxylic acid monomers such as 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methylenecarboxypropane, and 1,2,7,8-octanetetracarboxylic acid.

In addition to the above-mentioned monomer raw materials, raw material monomers for polyester polyamide and polyamide include monomers that form amide components, such as polyamines such as ethylenediamine, pentamethylenediamine, hexamethylenediamine, phenylenediamine, and triethylenetetramine, and aminocarboxylic acids such as 6-aminocaproic acid and ε-caprolactam. Here, the glass transition temperature Tg of the resin is, for example, 55°C or higher, more preferably 57°C or higher, in terms of thermal storage stability.

Polymer resins obtained by addition polymerization reactions are typically vinyl resins obtained by radical polymerization, but are not particularly limited thereto. Raw monomers for addition polymerization resins include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, vinylnaphthalene, ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene, vinyl esters such as vinyl chloride, vinyl bromide, vinyl acetate, and vinyl formate, and acrylic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, tert-butyl acrylate, amyl acrylate, methacrylic acid, methyl methacrylate, and ethyl methacrylate. Examples of the crosslinking agent include ethylenic monocarboxylic acids and esters thereof such as ethylenic monocarboxylic acids, n-propyl methacrylate, isopropyl methacrylate, tert-butyl methacrylate, amyl methacrylate, stearyl methacrylate, methoxyethyl methacrylate, glycidyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate; ethylenic monocarboxylic acid substitutes such as acrylonitrile, methacrylonitrile, and acrylamide; ethylenic dicarboxylic acids and substitutes thereof such as dimethyl maleate; and vinyl ketones such as vinyl methyl ketone. If necessary, a crosslinking agent can be added. Examples of the crosslinking agent for the addition polymerization monomer include general crosslinking agents such as divinylbenzene, divinylnaphthalene, polyethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, and diallyl phthalate.

The amount of these crosslinking agents used is 0.05 to 15 parts by mass, and more preferably 0.1 to 10 parts by mass, based on 100 parts of the raw material monomer of the addition polymerization resin. By using 0.05 parts by mass or more, the effect of the crosslinking agent is manifested, and by using 15 parts by mass or less, melting by heat becomes easier, and the toner is fixed well when fixed using heat.

A polymerization initiator is used when polymerizing the raw material monomers of the addition polymerization resin. Examples include 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, other azo or diazo polymerization initiators, or peroxide polymerization initiators such as benzoyl peroxide, methyl ethyl ketone peroxide, and 2,4-dichlorobenzoyl peroxide. Two or more types of polymerization initiators can be mixed and used to adjust the molecular weight and molecular weight distribution of the polymer. The amount of polymerization initiator used is 0.05 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, based on 100 parts of the raw material monomers of the addition polymerization resin.

In these condensation polymerization reactions or addition polymerization reactions, depending on the difference in the reaction raw materials, the resulting polymer resin may be a polymer having a non-linear structure or a polymer having a linear structure. In the present invention, both non-linear polymer resin (A) and linear polymer resin (B) can be used. In the present invention, non-linear polymer resin means a polymer resin having a substantial cross-linked structure, and linear polymer resin means a polymer resin having substantially no cross-linked structure.

In the present invention, in order to obtain a hybrid resin in which a condensation polymerization resin and an addition polymerization resin are chemically bonded, it is preferable to carry out polymerization using a compound capable of reacting with both monomers of the resins. Examples of such a dual-reactive monomer include compounds such as fumaric acid, acrylic acid, methacrylic acid, maleic acid, and dimethyl fumarate.
The amount of the bireactive monomer used is 1 to 25 parts by mass, preferably 2 to 10 parts by mass, based on 100 parts by mass of the raw material monomer of the addition polymerization resin. When the amount is 1 part by mass or more, the colorant and charge control agent are dispersed well, and image quality problems such as fogging can be prevented, and when the amount is 25 parts by mass or less, gelation of the resin can be prevented.

The above hybrid resin does not require both reactions to proceed and complete simultaneously, and each reaction can be completed independently by selecting the reaction temperature and time for each. For example, a method is available in which a mixture of vinyl resin addition polymerization raw material monomers and a polymerization initiator is dripped into a mixture of polyester resin condensation polymerization raw material monomers in a reaction vessel and mixed in advance, first completing the polymerization reaction of the vinyl resin by a radical reaction, and then completing the condensation polymerization reaction of the polyester resin by raising the reaction temperature. With this method, two independent reactions can proceed in parallel in the reaction vessel, making it possible to effectively disperse the two types of resin.

In the present invention, resins other than those described above can be used as the resin component in the toner, provided that the toner performance is not impaired. Examples of resins that can be used in this case include, but are not limited to, polyurethane resins, silicone resins, ketone resins, petroleum-based resins, and hydrogenated petroleum-based resins. These resins can be used alone or in combination of two or more.

<<Other ingredients>>
The other components are not particularly limited and may be appropriately selected depending on the purpose. Examples of the other components include colorants, charge control agents, flowability improvers, cleaning improvers, and magnetic materials.

- Coloring agent -
The colorant is not particularly limited and can be appropriately selected depending on the purpose. Examples of the colorant include carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, yellow ocher, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Balkan fast yellow (5G, R), tartrazine lake, quinoline yellow lake, anthrazan yellow BGL, isoindolinone yellow, Red iron oxide, red lead, vermilion, cadmium red, cadmium mercury red, antimony vermilion, permanent red 4R, para red, phisee red, parachlor orthonitroaniline red, lithol fast scarlet G, brilliant fast scarlet, brilliant carmine BS, permanent red (F2R, F4R, FRL, FRLL, F4RH), fast scarlet VD, belkan fast rubin B, brilliant scarlet G, lithol rubin GX, permanent red F5R, brilliant carmine 6B, pigment scarlet 3B, bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red, Polyazo Red, Chrome Vermilion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal-free Phthalocyanine Blue, Phthalo Examples of the pigments include cyanine blue, fast sky blue, indanthrene blue (RS, BC), indigo, ultramarine blue, Prussian blue, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment green B, naphthol green B, green gold, acid green lake, malachite green lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc oxide, and lithopone.
The content of the colorant is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1 part by mass or more and 15 parts by mass or less, and more preferably 3 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the toner.

The colorant can also be used as a masterbatch composited with a resin. Examples of resins to be used in the preparation of the masterbatch or to be kneaded together with the masterbatch include, in addition to the amorphous polyester resin, polymers of styrene or its substitutes, such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, and styrene-α-chloromethyl methacrylate copolymer. Examples of the styrene-based copolymers include styrene-acrylonitrile copolymers, styrene-vinyl methyl ketone copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-acrylonitrile-indene copolymers, styrene-maleic acid copolymers, and styrene-maleic acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resins, epoxy polyol resins, polyurethanes, polyamides, polyvinyl butyral, polyacrylic acid resins, rosin, modified rosin, terpene resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, and paraffin waxes. These may be used alone or in combination of two or more.
The master batch can be obtained by mixing and kneading a resin for the master batch and a colorant under high shear force. In this case, an organic solvent can be used to enhance the interaction between the colorant and the resin. In addition, a method called a flushing method, in which an aqueous paste containing water of the colorant is mixed and kneaded with a resin and an organic solvent, the colorant is transferred to the resin side, and the water and organic solvent components are removed, is also preferably used because the wet cake of the colorant can be used as it is and does not need to be dried. A high shear dispersing device such as a three-roll mill is preferably used for mixing and kneading.

-Charge control agent-
The charge control agent is not particularly limited and can be appropriately selected depending on the purpose. Examples of the charge control agent include nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdic acid chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), alkylamides, phosphorus simple substance or compounds, tungsten simple substance or compounds, fluorine-based activators, metal salicylate, and metal salts of salicylic acid derivatives.
Specific examples include the nigrosine dye Bontron 03, the quaternary ammonium salt Bontron P-51, the metal-containing azo dye Bontron S-34, the oxynaphthoic acid metal complex E-82, the salicylic acid metal complex E-84, and the phenol condensate E-89 (all manufactured by Orient Chemical Industry Co., Ltd.), the quaternary ammonium salt molybdenum complexes TP-302 and TP-415 (all manufactured by Hodogaya Chemical Co., Ltd.), LRA-901, the boron complex LR-147 (manufactured by Japan Carlit Co., Ltd.), copper phthalocyanine, perylene, quinacridone, azo pigments, and other polymeric compounds having functional groups such as sulfonic acid groups, carboxyl groups, and quaternary ammonium salts.
The content of the charge control agent is not particularly limited and can be appropriately selected according to the purpose, but is preferably 0.1 parts by mass or more and 10 parts by mass or less, more preferably 0.2 parts by mass or more and 5 parts by mass or less, relative to 100 parts by mass of the toner. When the content is 10 parts by mass or less, the chargeability of the toner is appropriate, the effect of the main charge control agent is good, the electrostatic attraction force with the developing roller is appropriate, the fluidity of the developer is good, and a high image density is obtained. These charge control agents can be melt-kneaded with the master batch and resin and then dissolved and dispersed, or can be added when directly dissolved and dispersed in an organic solvent, or can be fixed on the toner surface after the toner particles are produced.

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

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

(Toner Manufacturing Method)
The toner of the present invention can be produced by a conventional method, which involves mixing a resin component, a colorant, a wax component, and optionally a charge control agent, etc., using a mixer or the like, kneading the mixture using a kneading machine such as a heat roll or an extruder, cooling and solidifying the mixture, pulverizing the mixture using a pulverizer such as a jet mill, and then classifying the mixture to obtain the toner. The production method is not particularly limited, and any of bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization can be used.

(Replenishing Developer)
The carrier of the present invention is used as a refill developer consisting of a carrier and a toner, and is applied to an image forming apparatus that forms an image while discharging excess developer from a developing device, thereby obtaining a stable image quality for an extremely long period of time. In other words, the deteriorated carrier in the developing device is replaced with undegraded carrier in the refill developer, and the charge amount is kept stable for an extremely long period of time, resulting in a stable image. This method is particularly effective when printing a large image area. When printing a large image area, the main carrier deterioration is carrier charge deterioration due to toner spent on the carrier, but by using this method, the amount of carrier replenishment is also large when the image area is large, so the deteriorated carrier is replaced more frequently. This allows a stable image to be obtained for an extremely long period of time.

The mixing ratio of the replenishment developer is preferably 2 to 50 parts by weight of toner to 1 part by weight of carrier. If the toner is less than 2 parts by weight, the amount of replenishment carrier is too much, resulting in an oversupply of carrier and an excessive carrier concentration in the developing device, which tends to increase the charge amount of the developer. In addition, the increased charge amount of the developer reduces the development ability and reduces the image density. If the amount exceeds 50 parts by weight, the carrier ratio in the replenishment developer is low, which reduces the replacement of carrier in the image forming device and makes it difficult to expect any effect against carrier deterioration.

(Image forming apparatus and image forming method)
The image forming apparatus of the present invention is characterized by comprising an electrostatic latent image carrier, charging means for charging the electrostatic latent image carrier, exposure means for forming an electrostatic latent image on the electrostatic latent image carrier, a developer carrier which rotates in the vicinity of the electrostatic latent image carrier and carries the electrophotographic developer of the present invention, a developing device which develops the electrostatic latent image formed on the electrostatic latent image carrier with the electrophotographic developer of the present invention to form a toner image, transfer means for transferring the toner image formed on the electrostatic latent image carrier to a recording medium, and fixing means for fixing the toner image transferred to the recording medium, and further comprises other means appropriately selected as necessary, such as a static elimination means, a cleaning means, a recycling means, a control means, etc.
The image forming method of the present invention is characterized by comprising the steps of forming an electrostatic latent image on an electrostatic latent image carrier, developing the electrostatic latent image formed on the electrostatic latent image carrier with the electrophotographic developer of the present invention to form a toner image, transferring the toner image formed on the electrostatic latent image carrier to a recording medium, and fixing the toner image transferred to the recording medium, and further comprising other manual steps appropriately selected as necessary, such as a static elimination step, a cleaning step, a recycling step, a control step, etc.

(Process cartridge)
The process cartridge of the present invention is characterized by comprising: an electrostatic latent image carrier; a charging member for charging the surface of the electrostatic latent image carrier; a developing section for developing an electrostatic latent image formed on the electrostatic latent image carrier using the electrophotographic developer of the present invention; and a cleaning member for cleaning the electrostatic latent image carrier.

An example of the process cartridge of the present invention is shown in Fig. 1. The process cartridge (10) integrally supports a photoconductor (11), a charging device (12) that charges the photoconductor (11), a developing device (13) that develops an electrostatic latent image formed on the photoconductor (11) with the developer of the present invention to form a toner image, and a cleaning device (14) that removes toner remaining on the photoconductor (11) after the toner image formed on the photoconductor (11) is transferred to a recording medium, and the process cartridge (10) is detachably attached to the main body of an image forming apparatus such as a copier or printer.
Hereinafter, a method of forming an image using an image forming apparatus equipped with a process cartridge (10) will be described. First, the photoconductor (11) is rotated at a predetermined peripheral speed, and the peripheral surface of the photoconductor (11) is uniformly charged to a predetermined positive or negative potential by the charging device (12). Next, exposure light is irradiated onto the peripheral surface of the photoconductor (11) from an exposure device (not shown), such as a slit exposure type exposure device or an exposure device that scans and exposes with a laser beam, to sequentially form electrostatic latent images. Furthermore, the electrostatic latent images formed on the peripheral surface of the photoconductor (11) are developed by the developing device (13) using the developer of the present invention, to form toner images. Next, the toner images formed on the peripheral surface of the photoconductor (11) are sequentially transferred to transfer paper fed from a paper feed section (not shown) between the photoconductor (11) and a transfer device (not shown) in synchronization with the rotation of the photoconductor (11). Furthermore, the transfer paper onto which the toner image has been transferred is separated from the peripheral surface of the photoconductor (11) and introduced into a fixing device (not shown) where the toner image is fixed, and then printed out as a duplicate (copy) to the outside of the image forming apparatus. Meanwhile, the surface of the photoconductor (11) onto which the toner image has been transferred is cleaned by a cleaning device (14) to remove residual toner, and then discharged by a discharge device (not shown) for repeated use in image formation.

The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these. Note that "parts" refers to parts by mass.

(Toner Production Example)
First, a production example of a toner will be described. The softening temperature, glass transition point, and weight average molecular weight of a resin were measured as follows.

<Measurement of Softening Temperature (Tm) and Glass Transition Point (Tg) of Resin>
The softening temperature (Tm) was measured using a high-temperature flow tester (manufactured by Shimadzu Corporation) in accordance with the method described in JIS K72101. A ¹ cm3 sample was heated at a temperature rise rate of 6°C/min, while a load of 20 kg/ ^cm2 was applied by the plunger to push out a nozzle with a diameter of 1 mm and a length of 1 mm. As a result, a plunger drop-temperature curve was drawn, and when the height of the S-shaped curve was h, the temperature corresponding to h/2 (the temperature at which half of the resin flowed out) was taken as the softening point (Tm).
The glass transition point (Tg) was measured using a differential scanning calorimeter (DSC-60, manufactured by Shimadzu Corporation) by heating from room temperature (25° C.) to 200° C. at a rate of 10° C./min, then cooling to room temperature at a rate of 10° C./min, and then measuring at a rate of 10° C./min. The glass transition point (Tg) was determined as a curve in which the height h of the baseline below the glass transition point and the height h of the baseline above the glass transition point corresponded to 1/2.

<Weight average molecular weight (Mw) of resin>
The weight average molecular weight was measured using a GPC measuring device (HLC-8220GPC, manufactured by Tosoh Corporation) and a column (TSKgel SuperHZM-H 15 cm triplet, manufactured by Tosoh Corporation). Specifically, the column was stabilized in a heat chamber at 40 ° C. Next, tetrahydrofuran (THF) was passed through the column at a flow rate of 1 mL / min, and 50 μL to 200 μL of a THF solution of a 0.05% by mass to 0.6% by mass sample was injected to measure the weight average molecular weight of the sample. At this time, the number average molecular weight of the sample was calculated from the relationship between the logarithm value and the count number of a calibration curve created using several types of monodisperse polystyrene standard samples.
The standard polystyrene samples used were those having weight average molecular weights of 6×10 ² , 2.1×10 ³ , 4×10 ³ , 1.75×10 ⁴ , 5.1×10 ⁴ , 1.1×10 ⁵ , 3.9×10 ⁵ , 8.6×10 ⁵ , 2×10 ⁶ , and 4.48×10 ⁶ (manufactured by Pressure Chemical Co. or Tosoh Corporation).
As a detector, an RI (refractive index) detector was used.

(Production Example of Non-Linear Polyester Resin)
9.0 mol of fumaric acid, 3.5 mol of trimellitic anhydride, 5.5 mol of bisphenol A (2,2) propylene oxide, and 3.5 mol of bisphenol A (2,2) ethylene oxide were placed in a flask equipped with a stainless steel stirring rod, a downflow condenser, a nitrogen gas inlet tube, and a thermometer, and a condensation polymerization reaction was carried out with stirring at a temperature of 230° C. under a nitrogen atmosphere, to obtain a non-linear polyester resin A.
The resulting non-linear polyester resin A had a softening point (Tm) of 145.1° C., a glass transition point (Tg) of 61.5° C. and a weight average molecular weight (Mw) of 82,000.

(Production Example of Linear Polyester Resin)
7 mol of terephthalic acid, 2.5 mol of trimellitic anhydride, 5.5 mol of bisphenol A (2,2) propylene oxide, and 3.5 mol of bisphenol A (2,2) ethylene oxide were placed in a flask equipped with a stainless steel stirring rod, a downflow condenser, a nitrogen gas inlet tube, and a thermometer, and a condensation polymerization reaction was carried out with stirring at a temperature of 230° C. under a nitrogen atmosphere, to obtain a linear polyester resin B.
The resulting Linear Polyester Resin B had a softening point (Tm) of 102.8° C., a glass transition point (Tg) of 61.2° C. and a weight average molecular weight (Mw) of 8,000.

(Example of hybrid resin production)
18 mol of styrene as an addition polymerization reaction monomer, 4.5 mol of butyl methacrylate, and 0.35 mol of t-butyl hydroperoxide as a polymerization initiator were placed in a dropping funnel, and 9.0 mol of fumaric acid as an addition polymerization and condensation polymerization reactive monomer, 3.5 mol of trimellitic anhydride as condensation polymerization reaction monomers, 5.5 mol of bisphenol A (2,2) propylene oxide, 3.8 mol of bisphenol A (2,2) ethylene oxide, and 58 mol of dibutyltin oxide as an esterification catalyst were placed in a flask equipped with a stainless steel stirring rod, a downflow condenser, a nitrogen gas inlet tube, and a thermometer, and while stirring under a nitrogen atmosphere at 138° C., a mixture of addition polymerization raw materials was added dropwise from the dropping funnel over a period of 4 hours.
After completion of the reaction, the mixture was aged for 6 hours while maintaining the temperature at 138° C., and then the temperature was raised to 230° C. for reaction, thereby obtaining a hybrid resin C.
The resulting hybrid resin C had a softening point (Tm) of 151.5° C. and a glass transition point (Tg) of 62.1° C.
The obtained hybrid resin C had a composition of polyester resin (weight average molecular weight (Mw) = 48,000)/styrene-acrylic copolymer resin (weight average molecular weight (Mw) = 190,000) = 78/22 (mass ratio).

(Production Example 1 of Fluorine-Containing Alumina Particles)
Alumina powder with a BET specific surface area of 120 ^m2 /g was placed in a reaction tank, and a mixed solution of 8 g of heptadecafluorodecyltrimethoxysilane and 1.8 g of hexamethyldisilazane was sprayed onto 100 g of the alumina powder while stirring under a nitrogen atmosphere. The mixture was heated and stirred at 220°C for 150 minutes, and then cooled to obtain fluorine-containing alumina particles 1.

(Production Example 2 of Fluorine-Containing Alumina Particles)
Alumina powder with a BET specific surface area of 120 ^m2 /g was placed in a reaction tank, and a mixed solution of 4 g of heptadecafluorodecyltrimethoxysilane and 0.5 g of hexamethyldisilazane was sprayed onto 100 g of the alumina powder while stirring under a nitrogen atmosphere. The mixture was heated and stirred at 220°C for 150 minutes, and then cooled to obtain fluorine-containing alumina particles 2.

(Toner Production Example 1)
[Toner formulation]
Non-linear polyester resin A: 42 parts by weight Linear polyester resin B: 45 parts by weight Hybrid resin C: 13 parts by weight Carbon black: 18 parts by weight Charge control agent (Spiron Black TR-H, manufactured by Hodogaya Chemical Co., Ltd.): 2.5 parts by weight Release agent (low molecular weight polypropylene, weight average molecular weight (Mw) = 5,500): 2.5 parts by weight

The above toner formulation was mixed and stirred in a Henschel mixer, then heated and melted in a roll mill at a temperature of 125°C to 130°C for 40 minutes, cooled to room temperature (25°C), and the resulting kneaded material was pulverized and classified in a jet mill to obtain toner base particles A with a volume average particle size of 7.0 μm and a particle size distribution in which 35% by number of particles are 5 μm or less.

Next, 1.2 parts by mass of silica (R-972, manufactured by Clariant Japan K.K.) and 0.4 parts by mass of fluorine-containing alumina particles 1 were added to 100 parts by mass of the toner base particles A, and the mixture was stirred and mixed using a Henschel mixer under the mixing conditions for inorganic particles described below. After that, large particles were removed through a mesh to obtain toner A.
-Mixing conditions-
Frequency: 80Hz
Time: 10 minutes

(Toner Production Example 2)
Toner B was obtained in the same manner as in Toner Production Example 1, except that in Toner Production Example 1, 1.2 parts by mass of silica (R-972, manufactured by Clariant Japan K.K.) and 1.0 part by mass of fluorine-containing alumina particles 2 were added per 100 parts by mass of toner base particles A, and the mixing conditions for the inorganic particles were changed to the following:
-Mixing conditions-
Frequency: 90Hz
Time: 15 min

(Toner Production Example 3)
Toner C was obtained in the same manner as in Toner Production Example 1, except that in Toner Production Example 1, 1.2 parts by mass of silica (R-972, manufactured by Clariant Japan K.K.) and 1.0 part by mass of fluorine-containing alumina particles 1 were added per 100 parts by mass of toner base particles A, and the mixing conditions for the inorganic particles were changed to the following:
-Mixing conditions-
Frequency: 90Hz
Time: 15 min

(Carrier manufacturing example)
<Synthesis of copolymer>
As described above, the weight average molecular weight was determined in terms of standard polystyrene using gel permeation chromatography. The viscosity was measured at 25°C in accordance with JIS-K2283. The non-volatile content was calculated according to the following formula by weighing 1 g of the coating composition into an aluminum dish, heating it at 150°C for 1 hour, and then measuring the mass.
Non-volatile content (%)=(mass before heating−mass after heating)×100/mass before heating Hereinafter, examples of synthesis of resins used in the present invention will be described.

(Resin Synthesis Example 1)
300 g of toluene was placed in a flask equipped with a stirrer and heated to 90° C. under a nitrogen gas flow. Next, a mixture of 84.4 g (200 mmol) of 3-methacryloxypropyltris(trimethylsiloxy)silane (Silaplane TM-0701T, manufactured by Chisso Corporation) represented by CH ₂ ═CMe-COO-C ₃ H ₆ -Si(OSiMe ₃ ) ₃ (wherein Me is a methyl group), 39 g (150 mmol) of 3-methacryloxypropylmethyldiethoxysilane, 65.0 g (650 mmol) of methyl methacrylate, and 0.58 g (3 mmol) of 2,2′-azobis-2-methylbutyronitrile was added dropwise to the flask over a period of 1 hour.
After the dropwise addition was completed, a solution of 0.06 g (0.3 mmol) of 2,2'-azobis-2-methylbutyronitrile dissolved in 15 g of toluene (total amount of 2,2'-azobis-2-methylbutyronitrile: 0.64 g = 3.3 mmol) was further added, and the mixture was mixed at 90 to 100°C for 3 hours to effect radical copolymerization, thereby obtaining a methacrylic copolymer A.
The weight average molecular weight of the obtained methacrylic copolymer A was 34,000. The methacrylic copolymer solution was then diluted with toluene so that the non-volatile content of the solution was 25% by mass. The viscosity of the copolymer solution thus obtained was 8.8 mm ² /s, and the specific gravity was 0.91.

(Resin Synthesis Example 2)
A methacrylic copolymer B was obtained by radical copolymerization in exactly the same manner as in Resin Synthesis Example 1, except that in Resin Synthesis Example 1, 84.4 g (200 mmol) of 3-methacryloxypropyltris(trimethylsiloxy)silane (Silaplane TM-0701T, manufactured by Chisso Corporation) was changed to 126.6 g (300 mmol), 3-methacryloxypropylmethyldiethoxysilane was changed to 33.8 g (130 mmol), and 65.0 g (650 mmol) of methyl methacrylate was changed to 57.0 g (570 mmol).
The weight average molecular weight of the resulting methacrylic copolymer B was 35,000. The methacrylic copolymer solution was then diluted with toluene so that the non-volatile content of the solution was 25% by mass. The viscosity of the copolymer solution thus obtained was 8.7 mm ² /s, and the specific gravity was 0.91.

(Resin Synthesis Example 3)
A methacrylic copolymer C was obtained by radical copolymerization in exactly the same manner as in Resin Synthesis Example 1, except that in Resin Synthesis Example 1, 84.4 g (200 mmol) of 3-methacryloxypropyltris(trimethylsiloxy)silane (Silaplane TM-0701T, manufactured by Chisso Corporation) was changed to 46.4 g (110 mmol), 3-methacryloxypropylmethyldiethoxysilane was changed to 31.2 g (120 mmol), and 65.0 g (650 mmol) of methyl methacrylate was changed to 77.0 g (770 mmol).
The weight average molecular weight of the resulting methacrylic copolymer C was 33,000. The methacrylic copolymer solution was then diluted with toluene to a non-volatile content of 25% by mass. The viscosity of the copolymer solution thus obtained was 8.7 mm ² /s, and the specific gravity was 0.91.

(Resin Synthesis Example 4)
Radical copolymerization was carried out in the same manner as in Resin Synthesis Example 1, except that in Resin Synthesis Example 1, 3-methacryloxypropylmethyldiethoxysilane was changed from 39 g (150 mmol) to 26 g (100 mmol) and methyl methacrylate was changed from 65.0 g (650 mmol) to 70.0 g (700 mmol), to obtain a methacrylic copolymer D.
The weight average molecular weight of the obtained methacrylic copolymer D was 34,000. The methacrylic copolymer solution was then diluted with toluene so that the non-volatile content of the solution became 25% by mass. The viscosity of the copolymer solution thus obtained was 8.8 mm ² /s, and the specific gravity was 0.91.

(Carrier Production Example 1)
(Production of resin liquid 1)
Methacrylic copolymer A (solids concentration: 25%) 3400 parts Aminosilane (solids concentration: 100%) 30 parts Toluene 4800 parts The above materials were dispersed in a homomixer for 10 minutes to prepare resin liquid 1 for forming a resin layer.

(Production of Resin Layer-Coated Carrier)
MnMg ferrite particles with a volume average particle size of 35 μm were used as carrier core particles, and the above resin liquid 1 was applied to the surface of the core particles at a rate of 30 g/min in an atmosphere of 60° C. using a Spiracoater (manufactured by Okada Seiko Co., Ltd.) so that the thickness was 0.50 μm, and then dried. The obtained carrier was left to stand in an electric furnace at 230° C. for 1 hour for firing, and after cooling, it was crushed using a sieve with a mesh size of 100 μm to obtain [Carrier 1]. The average thickness T was 0.50 μm.
The volume average particle size of the core particles was measured using a Microtrac particle size analyzer (Nikkiso Co., Ltd., SRA type) with the range set to 0.7 μm or more and 125 μm or less.
The thickness T (μm) from the surface of the core particle to the surface of the resin layer was determined by observing the cross section of the carrier using a transmission electron microscope (TEM), measuring the thickness T from the surface of the core particle to the surface of the resin layer at 50 points at intervals of 0.2 μm along the carrier surface, and averaging the measured values obtained.

(Carrier Manufacturing Example 2)
(Resin Liquid 2)
Methacrylic copolymer B (solid content: 25%) 3,400 parts Aminosilane (solid content: 100%) 30 parts Toluene 4,800 parts [Carrier 2] was obtained in the same manner as in Carrier Production Example 1, except that Resin Liquid 1 in Carrier Production Example 1 was changed to Resin Liquid 2.

(Carrier Production Example 3)
(Resin Liquid 3)
Methacrylic copolymer C (solid content: 25%) 3,400 parts Aminosilane (solid content: 100%) 30 parts Toluene 4,800 parts [Carrier 3] was obtained in the same manner as in Carrier Production Example 1, except that Resin Liquid 1 in Carrier Production Example 1 was changed to Resin Liquid 3.

(Carrier Production Example 4)
(Resin Liquid 4)
- Methacrylic copolymer D (solid content: 25%) 3,400 parts - Aminosilane (solid content: 100%) 30 parts - Toluene 4,800 parts [Carrier 4] was obtained in the same manner as in Carrier Production Example 1, except that Resin Liquid 1 in Carrier Production Example 1 was changed to Resin Liquid 4.

(Carrier Production Example 5)
(Resin Liquid 5)
(Production of resin liquid 5)
Silicone resin solution [SR2410: manufactured by Toray Dow Corning Silicone Co., Ltd.]
(solid content concentration: 20%) 4,200 parts Aminosilane (solid content concentration: 100%) 30 parts Toluene 4,000 parts [Carrier 5] was obtained in the same manner as in Carrier Production Example 1, except that Resin Liquid 1 in Carrier Production Example 1 was changed to Resin Liquid 5.

(Carrier Production Example 6)
(Resin Liquid 6)
Acrylic resin solution [Hitaroid 3001: manufactured by Hitachi Chemical Co., Ltd.]
(Solid content concentration: 50%) 500 parts of guanamine solution [Mycoat 106: manufactured by MT Aquapolymer Co., Ltd.]
(Solid content: 70%) 90 parts Acid catalyst 0.25 parts by mass [Catalyst 4040: manufactured by MT Aqua Polymer Co., Ltd.]
(Solid content concentration: 40%) 3 parts silicone resin solution [SR2410: manufactured by Toray Dow Corning Silicone Co., Ltd.]
(Solid content concentration: 20%) 2,100 parts Aminosilane (Solid content concentration: 100%) 30 parts Toluene 5,400 parts [Carrier 6] was obtained in the same manner as in Carrier Production Example 1, except that Resin Liquid 1 in Carrier Production Example 1 was changed to Resin Liquid 6.

[Example 1]
Developer 1 was prepared by mixing 7 parts by weight of Toner A obtained in Toner Production Example 1 and 93 parts by weight of Carrier 1 obtained in Carrier Production Example 1 in a mixer for 3 minutes.

[Example 2]
Developer 2 was prepared in the same manner as in Example 1, except that Carrier 1 was changed to Carrier 2.

[Example 3]
Developer 3 was prepared in the same manner as in Example 1, except that Carrier 1 was changed to Carrier 3.

[Example 4]
Developer 4 was prepared in the same manner as in Example 1, except that Carrier 1 was changed to Carrier 4.

[Example 5]
Developer 5 was prepared in the same manner as in Example 1, except that toner A was changed to toner B.

[Example 6]
Developer 6 was prepared in the same manner as in Example 1, except that toner A was changed to toner C.

[Comparative Example 1]
Developer 7 was prepared in the same manner as in Example 1, except that Carrier 1 was changed to Carrier 5.

[Comparative Example 2]
Developer 8 was prepared in the same manner as in Example 1, except that Carrier 1 was changed to Carrier 6.

For the resulting developers, the composition of the resin layer of each carrier, the aluminum concentration (atomic%) X1 of each toner determined by X-ray photoelectron spectroscopy (XPS), and the ratio of X1 to the fluorine concentration (atomic%) X2 are shown in Table 1.

(Developer characteristic evaluation)
The resulting developer was subjected to the following evaluations.
To evaluate the carrier scraping and resistance fluctuation during long-term printing, edge carrier adhesion and solid carrier adhesion were evaluated, and toner scattering, background fogging, and ID were evaluated to evaluate the charging stability during long-term printing.

The resulting developer was used in a commercially available digital full-color multifunction printer (Ricoh Co., Ltd., Pro C9100) and image evaluation was performed.

(Toner scattering)
After the 1,000,000 sheets were printed, the amount of toner remaining in the lower part of the developer carrying member was sucked and collected, and the weight of the toner was measured.
0 mg or more to less than 50 mg: ◎ (very good)
50 mg or more but less than 100 mg: ○ (good)
100mg or more but less than 250mg: △ (usable)
250mg or more: × (defective)

(Skin cover)
One of the important aims of the present invention is to obtain a stable charging ability for a long period of time from the start of printing by the charge performance imparting fine particles. One method for evaluating this aim is to evaluate background fogging.
After 1 million sheets were printed, the development of the blank image was stopped, the toner on the photoreceptor after development was transferred to tape, and the difference in image density (ΔID) from that of the untransferred tape was measured using a 938 spectrodensitometer (manufactured by X-Rite). The evaluation criteria are as follows:
0 or more and less than 0.005: ◎ (very good)
0.005 or more to less than 0.01: ○ (good)
0.01 or more and less than 0.02: △ (usable)
0.02 or more: × (defective)

(Edge carrier adhesion)
The machine was placed in an environmental evaluation room (low-temperature, low-humidity environment of 10° C. and 15%) and left for a day, after which edge carrier adhesion was evaluated using each developer.
Under the development conditions (charging potential (Vd): -630 V, development bias: DC -500 V), an image in which solid areas and blank paper were arranged vertically and horizontally alternately, with 170 μm x 170 μm as one square, was output on A3 size, and the number of white spots in the image due to carrier adhesion at the boundary of each square was counted. The evaluation criteria are shown below.
0: ◎ (very good)
1 to 3 pieces: ○ (good)
4 to 10 pieces: △ (available)
11 or more: × (defective)

(Solid carrier adhesion)
The machine was placed in a laboratory environment (25° C., 60% humidity) and solid carrier adhesion was evaluated using each developer.
A solid image was formed under specified development conditions (charging potential (Vd): -600 V, potential after exposure of image area (solid original): -100 V, development bias: DC -500 V), and image formation was interrupted by a method such as turning off the power during image formation, and the number of carrier particles adhering to the photoconductor after transfer was counted and evaluated. The area to be evaluated was a 10 mm x 100 mm area on the photoconductor. The evaluation criteria are shown below.
0: ◎ (very good)
1 to 3 pieces: ○ (good)
4 to 10 pieces: △ (available)
11 or more: × (defective)

(ID)
The machine was placed in an environmental evaluation room (a low-temperature, low-humidity environment of 10°C and 15%) and run for 100,000 sheets (100,000 sheets). After that, three sheets each of white solid and black solid images were printed on A3 paper (brand: RICOH MyPaper), and the image density (visual evaluation) on the image samples was evaluated.
The above evaluation results were ranked in the following four stages.
◎: Very good, ○: Good, △: Usable, ×: Bad

The results of the image evaluation are shown in Table 2.

10: process cartridge 11: photoconductor 12: charging device 13: developing device 14: cleaning device

Japanese Patent Application Publication No. 60-93455 Japanese Unexamined Patent Publication No. 58-108548 Special Publication No. 1-19584 Special Publication No. 3-628 Japanese Patent Application Publication No. 6-202381 Patent No. 3691115

Claims (8)

A developer for electrophotography comprising a toner containing inorganic particles and a carrier having core particles and a resin layer covering the surfaces of the core particles,
the toner contains at least fluorine-containing alumina particles as the inorganic particles, and the resin layer contains an acrylic silicone resin,
The electrophotographic developer , wherein the acrylic silicone resin contains a crosslinked product of a copolymer containing at least a component A represented by the following general formula (A) and a component B represented by the following general formula (B) :
(In formulas (A) and (B), R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkyl group having 1 to 4 carbon atoms, R ³ represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and m represents an integer of 1 to 8. A plurality of R ² may be the same or different. X represents 10 to 90 mol %, and Y represents 90 to 10 mol %). 2. The electrophotographic developer according to claim 1 , wherein the copolymer contains a copolymer represented by the following general formula (1):
(In formula (1), R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkyl group having 1 to 4 carbon atoms, R ³ represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and m represents an integer of 1 to 8. A plurality of R ² may be the same or different. X represents 10 to 40 mol %, Y represents 10 to 40 mol %, Z represents 30 to 80 mol %, and 60 mol %≦Y+Z≦90 mol %). 3. The electrophotographic developer according to claim 1, wherein when an aluminum concentration (atomic %) in the toner determined by X-ray photoelectron spectroscopy (XPS) is X1 and a fluorine concentration (atomic %) in the toner is X2, the toner satisfies the following relational expressions (2) and (3):
2.7≦X1/X2≦5.5 Formula (2)
2.1≦X1≦3.0 Formula (3) 4. The electrophotographic developer according to claim 1, wherein the toner further contains inorganic particles other than the fluorine-containing alumina particles, and the median diameter of the inorganic particles other than the fluorine-containing alumina particles is 60 nm or more and 300 nm or less. A replenishing developer comprising a carrier and a toner, the replenishing developer being the developer according to any one of claims 1 to 4 , and containing 2 parts by mass or more and 50 parts by mass or less of the toner per 1 part by mass of the carrier. an exposure means for forming an electrostatic latent image on the electrostatic latent image carrier; a developer carrier that rotates in the vicinity of the electrostatic latent image carrier and carries the developer for electrophotography according to any one of claims 1 to 4 ; a developing device that develops the electrostatic latent image formed on the electrostatic latent image carrier with the developer for electrophotography according to any one of claims 1 to 4 to form a toner image; a transfer means that transfers the toner image formed on the electrostatic latent image carrier to a recording medium; and a fixing means that fixes the toner image transferred to the recording medium. 5. A process cartridge comprising: an electrostatic latent image carrier; a charging member for charging a surface of the electrostatic latent image carrier; a developing section for developing an electrostatic latent image formed on the electrostatic latent image carrier by using the electrophotographic developer according to claim 1; and a cleaning member for cleaning the electrostatic latent image carrier. 5. An image forming method comprising the steps of: forming an electrostatic latent image on an electrostatic latent image carrier; developing the electrostatic latent image formed on the electrostatic latent image carrier with the electrophotographic developer according to any one of claims 1 to 4 to form a toner image; transferring the toner image formed on the electrostatic latent image carrier to a recording medium; and fixing the toner image transferred to the recording medium.

Images