JP2012189880A - Carrier, developer, process cartridge, and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carrier having stable charging ability, excellent in abrasion resistance of a film, showing less changes in the carrier resistance and in a pumping amount of a developer, restricting toner spent, showing less image density variation, and preventing contamination due to background contamination, toner scattering, and carrier adhesion.SOLUTION: A carrier is configured such that the surface of a core material is coated with a silane coupling agent and thereafter coated with a coating resin layer containing a silicone resin containing conductive fine particles. The arithmetic average roughness Ra of the core material is 0.6 to 0.9 μm and this arithmetic average roughness Ra is equal to or larger than the average thickness of the coating resin layer.

Description

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

  In an electrophotographic image forming method, an electrostatic latent image formed on a photoreceptor is developed with a developer containing toner, and visualized through a transfer and fixing process. Developers used for development include a two-component developer composed of a toner and a carrier, and a one-component developer such as a magnetic toner.

  In the two-component developer, the carrier shares functions such as stirring, transporting and charging of the developer. Among these, carriers coated with a coating resin such as a fluororesin or a silicone resin are widely used because of excellent charge controllability and carrier life.

  In recent years, with the demand for higher image quality and higher speed, there is a tendency to reduce the particle size of toner and increase the printer speed, and toner spent tends to occur. Further, in addition to the problem of toner spent, when the coating resin is peeled off, the carrier resistance and the developer pumping amount change. As a result, there is a problem that the image density changes and color stains occur.

  In order to solve these problems, Patent Document 1 discloses an attempt to prevent toner spent by forming irregularities on the surface of the carrier, scraping off the spent on the surface of the carrier. Moreover, in patent document 2, two or more types of coat resin is coat | covered on the core material surface with large unevenness | corrugation, the adhesive force of coat resin is raised by making the difference of the acid value of coat resin small, and peeling resistance is improved. Attempts have been disclosed.

  However, Patent Document 1 does not take measures against problems such as breakage of a convex portion where friction and impact are concentrated, peeling of a convex coat film, and occurrence of a difference in coat layer thickness between the convex portion and the concave portion. Moreover, in patent document 2, although the adhesive force between resin is raised, the adhesive force between a core material and resin is low.

  Therefore, the present invention has a stable charge imparting ability, excellent film abrasion resistance, little change in carrier resistance and developer pumping amount, suppresses toner spent, little fluctuation in image density, and low soil contamination. An object of the present invention is to provide a carrier that is free from contamination due to toner scattering and carrier adhesion.

  According to the present invention, the core is coated with a coating resin layer containing a silicone resin containing conductive fine particles after the surface of the core is coated with a silane coupling agent, and the arithmetic average roughness Ra of the core is 0. A carrier having a thickness of 0.6 to 0.9 μm and an arithmetic average roughness Ra equal to or greater than an average thickness of the coat resin layer is provided.

  According to the present invention, it has stable charge imparting ability, excellent film abrasion resistance, little change in carrier resistance and developer pumping amount, toner spent can be suppressed, image density variation is small, In addition, it is possible to provide a carrier that does not cause contamination due to toner scattering and carrier adhesion.

FIG. 1 is a diagram for explaining the effect of the carrier of the present invention, and is a schematic diagram relating to a cross section of the carrier. FIG. 2 is a schematic diagram relating to the developing unit of the image forming apparatus illustrating the present invention. FIG. 3 is a schematic view of an image forming apparatus illustrating the present invention. FIG. 4 is a schematic view of another example of the image forming apparatus of the present invention. FIG. 5 is an example of the process cartridge of the present invention. FIG. 6 is an example of a test chart using the developer of the present invention.

    Hereinafter, the present invention will be described in detail.

  The carrier of the present invention is a carrier in which the surface of the core material is coated with a silane coupling agent and then coated with a coating resin layer containing a silicone resin containing conductive fine particles, and the arithmetic average roughness Ra of the core material is By setting the arithmetic average roughness Ra to be equal to or greater than the average thickness of the coat resin layer, various effects described later can be obtained.

[Arithmetic mean roughness Ra of core material and thickness of coated resin layer]
In the carrier according to the present invention, the spent toner scraping action works by forming the carrier using a core material having an arithmetic mean roughness Ra of 0.6 μm or more and 0.9 μm or less and a large degree of unevenness. As a result, generation of the toner spent described above can be suppressed.

  However, the ease of application of the subsequent coat resin layer differs between the convex portion and the concave portion. Therefore, the resin film thickness may be non-uniform compared to a smooth core material. Since the frictional force and the impact force are concentrated on the convex portion, film scraping and core material exposure occur. Further, when the core material exposure proceeds, an electric conduction path is formed, and the carrier resistance is rapidly reduced. As a result, problems such as carrier adhesion may occur during image formation. When Ra is less than 0.6 μm, the effect due to the presence of the unevenness as described above hardly appears. On the other hand, when Ra is larger than 0.9 μm, the surface non-uniformity becomes remarkable and the fluidity may deteriorate.

  Further, generally, when Ra is set to be equal to or greater than the average thickness of the coat resin layer, the scraping action of spent toner is increased, but the film thickness of the above-described convex portion is increased because the coat film thickness is thin. That is, it is difficult to satisfy both spent resistance and film abrasion resistance.

  In addition, arithmetic mean roughness Ra said here is measured according to JISB0601 (1994 edition). Briefly, an area of a particle surface of 12 × 12 μm is observed for 50 carriers using a super depth color 3D shape measurement microscope (VK-9500, manufactured by Keyence Corporation) at a magnification of 3000 times. A roughness curve is obtained from the observed three-dimensional shape of the core surface, and the measured value of the roughness curve and the absolute value of the deviation to the average line are summed and obtained by averaging. At this time, the reference length for calculating the arithmetic average roughness Ra is 10 μm, and the cutoff value is 0.08 mm.

[Application of silane coupling agent to core material]
In the carrier of the present invention, the film peeling of the convex portion is suppressed by coating the surface of the core material with the silane coupling agent. In general, when a coating resin is applied to the surface of the concavo-convex portion, uneven application tends to occur. However, by coating the surface of the core material with the silane coupling agent, the coating resin is uniformly and evenly applied to the surface of the concavo-convex portion. Therefore, conductive fine particles described later are also uniformly dispersed in the coating resin. Therefore, it is possible to prevent the coating resin and the conductive fine particles from peeling off (filler peeling).

  When the image quality of the carrier of the present invention is evaluated with an actual machine, it prevents the deterioration of the spent resistance due to the peeling of the large particle size filler, prevents the background stain (background stain) due to the decrease in the charge amount due to the toner spent, and prevents the scattering of the toner. In addition, there is a reduction in the pumping amount to the developing sleeve due to a change in carrier fluidity due to toner spent, and a suppression of a decrease in image density due to this. In addition, effects such as suppression of the film peeling of the protrusions described above, suppression of carrier resistance reduction due to the formation of an electrical conduction path due to expansion of the exposed core material, and suppression of carrier adhesion can also be obtained.

[Conductive fine particles having a large particle diameter of 0.15 to 0.5 μm]
In the carrier of the present invention, conductive fine particles having a particle size larger than usual and having a particle size of 0.15 to 0.5 μm are dispersed in the coating resin. Thereby, the spacer effect in the above-mentioned convex part is acquired, and the shaving of a convex part is suppressed more.

  However, local force may be applied to the conductive fine particles that form the convex portions on the carrier surface. As a result, the conductive fine particles and the surrounding coating resin may be peeled together. Therefore, it is necessary to firmly fix the conductive fine particles and the core material surface. In the present invention, after the above-mentioned silane coupling layer is formed on the surface of the core material, a coat resin layer containing a silicone resin containing conductive fine particles is formed. Thereby, a core material, resin, and microparticles | fine-particles can be adhere | attached firmly, and it becomes difficult to generate | occur | produce detachment | desorption of the large particle size filler used as the subject at the time of using a large particle size filler.

[Summary]
The abrasion resistance of the coat resin layer mainly depends on mechanical properties such as hardness and elasticity of the coat resin layer. That is, when the coating film is shaved and thinned, the carrier resistance is lowered, and problems such as carrier adhesion may occur. In the carrier of the present invention, the coating resin layer containing the silicone resin containing the conductive fine particles is formed, and the core material, the resin and the fine particles are firmly bonded to each other to prevent the coating resin layer from being worn due to rusting, Abrasion is ensured. Also, against the prevention of expansion of the exposed area of the core material at the convex part, the spacer effect by the uniform coat and large particle size filler by application of the silane coupling agent, the wear prevention by the filler effect, and the improved adhesion between the core material and the resin Due to the prevention of peeling, the core material exposed area does not increase over time, and the core material with large irregularities has inherent problems (preventing local wear and breakage of convex parts where frictional impact force is concentrated, by exposing the convex part core material Abrupt resistance drop, carrier adhesion, etc.) are prevented.

  FIG. 1 is a diagram for explaining the effect of the carrier of the present invention, and shows a schematic diagram relating to the cross section of the carrier. FIG. 1 schematically shows the progress of coating layer wear and peeling over time when the toner of the present invention and the conventional toner are used in an actual machine. FIG. 1A shows an example of a carrier in an initial state (before deterioration). FIG. 1B shows an example of a carrier in which the carrier of FIG. Furthermore, FIG.1 (c) shows the example of a carrier of the state in which deterioration with time advanced further with respect to the carrier of FIG.1 (b). In FIG. 1B and FIG. 1C, the top view 3 of the exposed portion of the core material is also shown.

  In the conventional carrier, the coating resin layer 2 and the core material 2 in FIG. 1 (a) are worn and peeled over time, and the core material exposed portion as shown in FIG. 1 (c). Spread locally. However, in the carrier of the present invention, since the wear and peeling of the coating resin layer 2 to the extent shown in FIG. 1B is stopped, the exposed area of the core material can be minimized.

  Further, in the developer using the carrier of the present invention, an ID difference is unlikely to occur between the leading edge of the image portion (one round of the developing sleeve) and the subsequent image portion, and the density loss in the solid image is small. The shape design of the carrier surface of the present invention is considered to be a factor.

  Next, materials for manufacturing the carrier of the present invention will be described.

[Silane coupling agent]
After forming the silane coupling layer on the surface of the core material, it is preferable to form a coat resin layer containing a silicone resin containing conductive fine particles. Thereby, a core material, coat resin, and electroconductive fine particles can be adhere | attached firmly. In addition, the filler is less likely to be detached.

  Although it does not limit as a silane coupling agent used for the carrier of this invention, From a viewpoint of adhesiveness and toner charge amount adjustment, it is preferable to use the aminosilane coupling agent shown below.

H ₂ N (CH ₂ ) ₃ Si (OCH ₃ ) ₃ (MW 179.3),
H ₂ N (CH ₂ ) ₃ Si (OC ₂ H ₅ ) ₃ (MW 221.4),
H ₂ NCH ₂ CH ₂ CH ₂ Si (CH ₃ ) ₂ (OC ₂ H ₅ ) (MW 161.3),
H ₂ NCH ₂ CH ₂ CH ₂ Si (CH ₃ ) (OC ₂ H ₅ ) ₂ (MW 191.3),
H ₂ NCH ₂ CH ₂ NHCH ₂ Si (OCH ₃ ) ₃ (MW 194.3),
_{H 2 NCH 2 CH 2 NHCH 2} CH 2 CH 2 Si (CH 3) (OCH 3) 2 (MW206.4),
_{H 2 NCH 2 CH 2 NHCH 2} CH 2 CH 2 Si (OCH 3) 3 (MW224.4),
(CH ₃ ) ₂ NCH ₂ CH ₂ CH ₂ Si (CH ₃ ) (OC ₂ H ₅ ) ₂ (MW 219.4),
_{(C 4 H 9) 2 NC} 3 H 6 Si (OCH 3) 3 (MW291.6) , and the like.

  The amount of the silane coupling agent to be used is not limited, but is preferably 0.001 to 30% by mass with respect to the mass of the core material. These silane coupling agents may be contained in a coating resin described later from the viewpoint of adjusting the toner charge amount of the coating layer.

[Coat resin]
The coating resin of the present invention preferably includes a silicone resin having a silanol group and / or a functional group capable of generating a silanol group by hydrolysis. Examples of the functional group capable of generating a silanol group by hydrolysis include negative groups such as an alkoxy group and a halogeno group bonded to a silicon atom. A silicone resin having a silanol group and / or a functional group capable of generating a silanol group by hydrolysis is used in combination with a cross-linking component of a copolymer described below or a cross-linking component in a state changed to a silanol group. Can be condensed. Moreover, the toner spent property of the carrier obtained can be improved by making the copolymer demonstrated below contain a silicone resin component.

  The silicone resin having a functional group capable of generating a silanol group and / or a silanol group by hydrolysis preferably contains any one of repeating units represented by the following general formula (1). .

Here, in the general formula (1), A ¹ is a hydrogen atom, a halogen atom, a hydroxy group, a methoxy group, a lower alkyl group having 1 to 4 carbon atoms, or an aryl group (such as a phenyl group or a tolyl group). A ² is an alkylene group having 1 to 4 carbon atoms or an arylene group (such as a phenylene group).

  Carbon number of the aryl group in General formula (1) is 6-20 normally, Preferably it is 6-14. As the aryl group, not only an aryl group derived from benzene (phenyl group) but also an aryl group derived from a condensed polycyclic aromatic hydrocarbon such as naphthalene, phenanthrene and anthracene can be used. Furthermore, aryl groups derived from chain polycyclic aromatic hydrocarbons such as biphenyl and terphenyl can be used. The aryl group may be substituted with other substituents.

  Carbon number of the arylene group in General formula (1) is 6-20 normally, Preferably it is 6-14. As the arylene group, not only an benzene-derived arylene group (phenylene group) but also an arylene group derived from a condensed polycyclic aromatic hydrocarbon such as naphthalene, phenanthrene, and anthracene can be used. Furthermore, an arylene group derived from a chain polycyclic aromatic hydrocarbon such as biphenyl or terphenyl can be used. The arylene group may be substituted with other substituents.

  It does not specifically limit as a commercial item of the silicone resin which can be used for this invention. Specifically, KR251, KR271, KR272, KR282, KR252, KR255, KR152, KR155, KR211, KR216, KR213 (manufactured by Shin-Etsu Silicone), AY42-170, SR2510, SR2400, SR2406, SR2405, SR2405, SR2411 (Toray Dow Corning Co., Ltd. or Toray Silicone Co., Ltd.).

  Among the above-mentioned silicone resins, it is preferable to use a methyl silicone resin. By using a methyl silicone resin, it is possible to produce a carrier that is excellent in low toner spent property and that has a small environmental fluctuation of charge amount.

  As a weight average molecular weight of a silicone resin, it is 1,000-100,000 normally, Preferably it is 1,000-30,000. When the weight average molecular weight of the silicone resin is greater than 100,000, a uniform coating film may not be formed because the viscosity of the coating solution is high. Further, the density of the coat resin layer may be lowered after curing. Moreover, when the weight average molecular weight of a silicone resin is smaller than 1,000, the coat resin layer after hardening may become brittle.

  As a content rate of a silicone resin, it is 5 mass%-80 mass% normally with respect to coat resin whole quantity, Preferably it is 10 mass%-60 mass%. When the content ratio of the silicone resin is less than 5% by mass, the effect of adding the silicone resin such as toner spent may not be obtained. Moreover, when there are more content rates of a silicone resin than 80 mass%, since the toughness of a coating resin layer is insufficient, film | membrane peeling may occur easily.

  The coating resin layer of the present invention may also contain a resin other than a silicone resin having a silanol group and / or a hydrolyzable functional group. Other resins that can be used in the coating resin layer of the present invention are not particularly limited, but are acrylic resin, amino resin, polyvinyl resin, polystyrene resin, halogenated olefin resin, polyester, polycarbonate, polyethylene, polyvinyl fluoride, polyvinyl fluoride. Fluoroterpolymers such as vinylidene fluoride, polytrifluoroethylene, polyhexafluoropropylene, copolymers of vinylidene fluoride and vinyl fluoride, terpolymers of tetrafluoroethylene, vinylidene fluoride and non-fluorinated monomers, silanol groups Or the silicone resin etc. which do not have a hydrolyzable functional group are mentioned. These resins may be used alone or in combination of two or more. Among the above resins, an acrylic resin is preferable because of its strong adhesion to the core particles and the conductive fine particles and low brittleness.

  The coating resin layer of the present invention is obtained by radical copolymerizing a monomer component having a repeating unit represented by the general formula (2) and a monomer component having a repeating unit represented by the general formula (3). It is preferable to use a resin having the copolymer obtained.

The details regarding R ¹ , (CH ₂ ) _m , R ² and R ³ in the general formula (2) are shown below.
R ¹ : a hydrogen atom or a methyl group,
_{(CH 2) m:} methylene group having 1 to 8 carbon atoms, an ethylene group, a propylene group and an alkylene group such as butylene group,
R ² : an aliphatic hydrocarbon group having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, a propyl group and a butyl group. The plurality of R ² may be the same or different.

  As a ratio of the monomer component which has a repeating unit represented by General formula (2) with respect to the said copolymer, it is 10-90 mol% normally, More preferably, it is 30-70 mol%. The monomer component having the repeating unit represented by the general formula (2) has tris (trimethylsiloxy) silane having a methyl group in the side chain. Therefore, when the ratio with respect to the copolymer exceeds 90 mol%, the surface energy is decreased, and adhesion of a resin component, a wax component or the like in the toner may be decreased. Further, the crosslinking reaction does not proceed sufficiently, the toughness is insufficient, the adhesiveness between the core material and the resin layer is lowered, and the durability of the carrier film may be deteriorated. On the other hand, when the ratio to the copolymer is less than 10 mol%, the adhesion of the toner component may increase rapidly.

Specific structural formulas of the monomer component having the repeating unit represented by the general formula (2) include those having the following structural formula. In the following structural formulas, 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, and so on.

  The manufacturing method of the monomer component which has a repeating unit represented by General formula (2) is not specifically limited. Examples thereof include a method of reacting tris (trialkylsiloxy) silane with allyl acrylate or allyl methacrylate in the presence of a platinum catalyst. In addition, it can be obtained by a method described in JP-A-11-217389, in which methacryloxyalkyltrialkoxysilane and hexaalkyldisiloxane are reacted in the presence of a carboxylic acid and an acid catalyst.

The details regarding R ⁴ , (CH ₂ ) _n , R ⁵ and R ⁶ in the general formula (3) are shown below.
R ⁴ : hydrogen atom or methyl group,
(CH ₂ ) _n : alkylene group such as methylene group having 1 to 8 carbon atoms, ethylene group, propylene group and butylene group,
R ⁵ : Aliphatic hydrocarbon groups such as methyl group, ethyl group, propyl group and butyl group having 1 to 4 carbon atoms, and a plurality of R ^{5 s} may be the same or different.
R ⁶ : an alkyl group having 1 to 8 carbon atoms (methyl group, ethyl group, propyl group, butyl group, etc.) or an alkoxy group having 1 to 4 carbon atoms (methoxy group, ethoxy group, propoxy group, butoxy group). .

  The ratio of the monomer component represented by the general formula (3) with respect to the copolymer is preferably 10 to 90 mol%, more preferably 30 to 70 mol%. When the ratio of the monomer component represented by the general formula (3) is less than 10 mol%, the toughness of the obtained carrier may be lowered. On the other hand, when it exceeds 90 mol%, the obtained carrier becomes brittle and film peeling may easily occur. In addition, environmental characteristics such as humidity dependency may deteriorate. A large number of hydrolyzed cross-linking components remain as silanol groups, which is considered to deteriorate the environmental characteristics.

  Examples of the monomer component represented by the general formula (3) include 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltriethoxysilane, Examples include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltri (isopropoxy) silane, and 3-acryloxypropyltri (isopropoxy) silane.

  In addition to the monomer component represented by the general formula (2) and the monomer component represented by the general formula (3), a monomer component represented by the general formula (4) is further added to produce a copolymer. May be.

In the general formula (4), R ⁶ and R ⁷ are as follows. )
R ⁶ : a hydrogen atom or a methyl group,
R ⁷ is an alkyl group having 1 to 4 carbon atoms.

  When adding the monomer component represented by the general formula (4), the ratio of the monomer component represented by the general formula (2) is 10 to 40 mol%, and the monomer component represented by the general formula (3) is The monomer component represented by the general formula (4) is preferably 30 to 80 mol%. Moreover, it is preferable that the sum total ratio of the monomer component represented by General formula (3) and the monomer component represented by General formula (4) is 60 mol%-90 mol%.

  By adding the monomer component represented by the general formula (4), the resulting coated resin film has flexibility. Moreover, the adhesiveness between the core material and the coating resin layer is improved. However, when the monomer component represented by the general formula (4) uses a copolymer of less than 30 mol%, sufficient adhesion may not be obtained. Moreover, when larger than 80 mol%, either the monomer component represented by General formula (2) and the monomer component represented by General formula (3) will be 10 mol% or less. Therefore, it may be difficult to achieve both water repellency, hardness and flexibility of the carrier coating.

  Examples of the precursor of the monomer component represented by the general formula (4) include acrylic acid esters and methacrylic acid esters. Specifically, methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, butyl methacrylate, butyl acrylate, 2- (dimethylamino) ethyl methacrylate, 2- (dimethylamino) ethyl acrylate, 3- (dimethylamino) propyl methacrylate, Examples include 3- (dimethylamino) propyl acrylate. Among the above compounds, alkyl methacrylate is preferably used, and methyl methacrylate is particularly preferable. Moreover, the said compound may be used individually by 1 type, and may use 2 or more types of mixtures.

  As a method for improving the durability of the carrier by crosslinking the coating resin, there is a method exemplified in Japanese Patent No. 3691115. Specifically, a radical copolymerizable monomer having at least one functional group selected from the group consisting of an organopolysiloxane having a vinyl group terminated with a magnetic particle surface and a hydroxyl group, an amino group, an amide group, and an imide group A carrier in which a copolymer with a body is coated with a thermosetting resin crosslinked with an isocyanate compound is disclosed. However, with this method, sufficient durability cannot be obtained in the case where the coated resin film is peeled off or scraped off. In the case of a thermosetting resin obtained by crosslinking the aforementioned copolymer with an isocyanate compound, there are few functional groups per unit weight that react with the isocyanate compound in the copolymer. That is, it is considered that a two-dimensional or three-dimensional dense crosslinked structure cannot be formed at the crosslinking point. For this reason, when this carrier is used for a long time, the coating has low wear resistance, so that the coating is easily peeled off or scraped off, and sufficient durability cannot be obtained.

  When the coated resin film is peeled off or scraped off, the carrier resistance is lowered, so that a change in image quality or carrier adhesion occurs. Further, the fluidity of the developer is lowered and the pumping amount is lowered, which causes a reduction in image density and toner scattering.

  The copolymer resin according to an embodiment of the present invention has many difunctional or trifunctional crosslinkable functional groups per unit weight of the resin. Furthermore, since this copolymer resin is cross-linked, the resulting coated film has a high toughness and is difficult to scrape, and a highly durable carrier can be obtained.

  The crosslinked structure of the present invention is achieved by a siloxane bond. In general, crosslinking by a siloxane bond has a larger binding energy and is stable against thermal stress than crosslinking by an isocyanate compound. That is, a carrier having excellent stability over time can be obtained.

  The coat resin according to one embodiment of the present invention preferably contains an acrylic resin. As an acrylic resin, it is preferable that a glass transition point is 20-100 degreeC, and 25-80 degreeC is more preferable. The acrylic resin has an appropriate elasticity and can absorb the impact caused by the friction between the toner and the carrier or the friction between the carriers when the developer is triboelectrically charged. Moreover, deterioration of the coating resin layer and the conductive fine particles can be prevented.

  The coating resin of the present invention preferably contains a resin obtained by crosslinking an acrylic resin and an amino resin. Thereby, coat resin has moderate elasticity and it can control fusion of coat resin layers.

  The amino resin is not particularly limited, but a melamine resin or a benzoguanamine resin is preferable because the charge imparting ability of the carrier can be improved. It is also preferable to use a melamine resin and / or a benzoguanamine resin in combination because the charge imparting ability of the carrier can be controlled.

  As an acrylic resin which can be cross-linked with an amino resin, those having a hydroxyl group and / or a carboxyl group are preferred, and those having a hydroxyl group are more preferred. By using an acrylic resin having a hydroxyl group, the adhesion to the core material particles and the conductive fine particles can be further improved. Also, the dispersion stability of the conductive fine particles can be improved. The acrylic resin used preferably has a hydroxyl value of 10 mgKOH / g or more, more preferably 20 mgKOH / g or more.

  In order to promote the condensation reaction of the crosslinking component in the coating resin such as a silicone resin having a silanol group and / or a hydrolyzable functional group, the following catalyst may be used. As the catalyst, a titanium catalyst, a tin catalyst, a zirconium catalyst, and an aluminum catalyst can be used. Among these, it is preferable to use a titanium catalyst, and it is more preferable to use a titanium alkoxide catalyst or a titanium chelate catalyst. A titanium alkoxide catalyst or a titanium chelate catalyst has a high effect of promoting the condensation reaction of silanol groups derived from the aforementioned crosslinking component. In addition, the catalyst is difficult to deactivate.

Examples of titanium alkoxide catalysts include titanium diisopropoxybis (ethyl acetoacetate) (Ti (Oi-C ₃ H ₇ ) ₂ (C ₆ H ₉ O ₃ ) ₂ ) and the like, and titanium chelate-based catalysts. examples of the catalyst include titanium diisopropoxy bis _{(triethanolaminate) (Ti (O-i-} C 3 H 7) 2 (C 6 H 14 O 3 N) 2) and the like.

  The coating resin layer according to one embodiment of the present invention includes a silicone resin having a silanol group and / or a hydrolyzable functional group, a titanium diisopropoxybis (ethylacetoacetate) catalyst, and other resins as necessary. It can form on the surface of core material particle | grains using the composition for resin layers to contain. Specifically, it can be formed by condensing silanol groups while coating the core particles with the resin layer composition. In addition, silanol groups may be condensed after coating the core particles with the resin layer composition. The method of condensing silanol groups while coating the core material particles with the resin layer composition is not particularly limited, but the method of coating the core particles with the resin layer composition while applying heat, light, etc. Etc. Further, the method of condensing the silanol group after coating the core material particles with the resin layer composition is not particularly limited, and examples thereof include a method of heating after coating the core material particles with the resin layer composition. .

[Coating resin layer strength and film thickness]
In the present invention, after coating the resin layer composition on the core material, heat treatment is performed at a temperature lower than the Curie point of the core material particles to be used, preferably 100 to 350 ° C, more preferably 150 to 250 ° C. As a result, the crosslinking reaction by condensation is promoted. When the heat treatment temperature is lower than 100 ° C., the crosslinking reaction by condensation may not proceed sufficiently. On the other hand, when the heat treatment temperature is higher than 350 ° C., the copolymer may be carbonized and the resin layer may be easily scraped.

  In this invention, it is preferable that the average film thickness of a coat resin layer is 0.1-0.3 micrometer. When the average film thickness is less than 0.1 μm, the resin layer may be easily peeled off. On the other hand, when the average film thickness exceeds 0.3 μm, since the resin layer is not a magnetic material, carriers may easily adhere to the image. In Examples described later, the average film thickness of the resin layer was measured by observing the cross section of the carrier using a transmission electron microscope (TEM).

[Conductive fine particles]
Next, the conductive fine particles in the present invention will be described.

  The coated resin layer of the carrier of the present invention preferably contains conductive fine particles comprising a substrate and a conductive coating layer. By including the conductive fine particles, the resistance of the carrier can be adjusted, and the strength of the coat resin layer can be improved. That is, the conductive fine particles adjust the resistance of a carrier coated with a resin obtained by heat-treating a silicone resin having a silanol group and / or a hydrolyzable functional group. In addition, the presence of conductive fine particles having a conductive coating layer on the surface of the alumina-based substrate increases the function of adjusting the volume resistivity of the carrier, and further reduces the surface energy and the tough copolymer. Combined with the affinity, the carrier resistance and the developer pumping amount do not change for a long time, the change in image density can be prevented, and a carrier capable of forming a high-quality image for a long time can be produced.

  It is preferable that the material used for the external additive of the toner and the material of the conductive fine particle substrate are separated from each other in terms of charging ability. Silica and titanium oxide, which are generally used as external additives for toner, have a high electronegativity and a large negative chargeability. For this reason, a conductive fine particle substrate having a low electronegativity increases the charging ability, which is preferable when a negatively charged toner is used. When alumina having a low electronegativity is used as the substrate, charging can be stably maintained for a long period of time, and a high-quality image can be formed. However, when a substrate having a large electronegativity such as titanium oxide other than alumina is used, it has an excellent charge control function in the initial stage of use, but the chargeability cannot be maintained by long-term use, and the image quality deteriorates. Sometimes.

As alumina, α-alumina, β-alumina and γ-alumina can be used, and the average particle diameter is preferably 0.1 μm to 0.5 μm. The specific surface area of alumina is usually 5 to 30 m ² / g, preferably 0.15 μm to 0.3 μm.

  The conductive coating layer preferably contains tin dioxide or tin dioxide and indium oxide. By using a conductive coating layer containing tin dioxide or tin dioxide and indium oxide, the substrate surface can be uniformly coated. Therefore, good conductivity can be obtained without being affected by the substrate. In particular, tin dioxide is preferable because the conductive coating layer is excellent in resistance adjusting ability and inexpensive.

  When tin dioxide is used as the conductive coating layer, the ratio of tin dioxide to the conductive fine particles is preferably 4% by mass or more and 80% by mass or less, and more preferably 30% by mass or more and 50% by mass or less. . When the content of tin dioxide is less than 4% by mass, the volume resistivity of the conductive fine particles is increased and the amount of the conductive fine particles added is increased, so that it may be easily detached from the surface of the carrier particles. Moreover, when content of tin dioxide exceeds 80 mass%, the effect of lowering | hanging the volume specific resistance of electroconductive fine particles is saturated, efficiency may worsen and it may become non-uniform | heterogenous.

  When tin dioxide and indium oxide are used as the conductive coating layer, the content of tin dioxide is 2% by mass or more and 7% by mass or less, and the content of indium oxide is 15% by mass or more and 40% by mass or less. preferable.

  The average primary particle diameter of the conductive fine particles was obtained from the average value by observing the cross section of the carrier using a transmission electron microscope (TEM), measuring the diameter of the conductive fine particles in the coating layer covering the carrier surface. . More specifically, the short diameter of arbitrary 10 conductive fine particles was measured from the carrier cross section, and the average of the measured values was obtained to obtain the average primary particle diameter.

  It is preferable that the addition amount of electroconductive particle is 3-8 mass% with respect to a core material. When the addition amount of the conductive particles is less than 3% by mass, the effect of adjusting the volume specific resistance of the carrier may be insufficient. On the other hand, when the addition amount of the conductive particles exceeds 8% by mass, it is difficult to hold the conductive fine particles, and the surface layer of the carrier may be destroyed.

[Carrier resistance]
The volume resistivity of the carrier of the present invention is preferably 1 × 10 ⁹ Ω · cm or more and 1 × 10 ¹⁷ Ω · cm or less. By controlling the volume resistivity of the carrier, it is possible to obtain a high-definition image with excellent color reproducibility and fine line reproducibility with reduced edge effect. When the volume resistivity is less than 1 × 10 ⁹ Ω · cm, carrier adhesion may occur in the non-image area. On the other hand, if the deposition resistivity exceeds 1 × 10 ¹⁷ Ω · cm, the edge effect may be at an unacceptable level.

  In general, the volume resistivity of the carrier can be adjusted by adjusting the resistance of the coating resin layer on the core particle (addition of conductive fine particles, etc.) and controlling the film thickness. Specifically, the conductive fine particle content with respect to 100 parts by mass of the resin of the coat resin layer is preferably 5 to 200 parts by mass. When the addition amount of the conductive fine particles is less than 5 parts by mass, the strength of the coat resin layer may be lowered, and the carrier resistance may be insufficiently adjusted. On the other hand, when the addition amount of the conductive fine particles exceeds 200 parts by mass, the conductive fine particles are likely to be detached, and the volume specific resistance of the carrier may be easily changed.

[Core particles]
The core material of the carrier of the present invention is not particularly limited as long as it is a magnetic material. For example, ferromagnetic metals such as iron and cobalt; iron oxides such as magnetite, hematite and ferrite; various alloys and compounds; Examples thereof include resin particles in which a magnetic material is dispersed in a resin. Among these, Mn-based ferrite, Mn-Mg-based ferrite, Mn-Mg-Sr-based ferrite, and the like are preferable in consideration of the environment.

  In the present invention, the core material particles preferably have a weight average particle diameter Dw in the range of 20 to 65 μm, and more preferably 20 to 45 μm. When the weight average particle diameter is larger than 65 μm, the toner is not developed faithfully with respect to the latent image, and the variation in the dot diameter may be increased and the graininess may be lowered. Further, when the toner concentration is high, the background may be easily soiled.

  Carrier adhesion refers to a phenomenon in which a carrier adheres to an image portion or background of an electrostatic latent image. The stronger the electric field in the image area of the electrostatic latent image or the background, the easier the carrier adhesion occurs. In the image area, the electric field is weakened by developing the toner, so that carrier adhesion is generally less likely to occur compared to the background area.

In the present invention, the weight average particle diameter of the carrier, the carrier core material, the toner, and the like is calculated based on the particle diameter distribution of the particles measured on the basis of the number, and is expressed by the following formula 1.
Dw = (1 / Σ (nD ³ )) * (Σ (nD ⁴ )) (Equation 1)
In the formula, D represents a representative particle size (μm) of particles present in each channel, and n represents the total number of particles present in each channel. The channel indicates a length for dividing the particle size range in the particle size distribution chart into measurement width units. In the present invention, an equal length of 2 μm (particle size distribution width) is adopted. . Further, as the representative particle size of the particles existing in each channel, the lower limit value of the particle size stored in each channel was adopted.

[Carrier shape and magnetization]
In the present invention, a carrier using a core material with a large unevenness degree having an arithmetic average roughness Ra of 0.6 to 0.9 μm is used as the core material. And the coating resin layer which has a silicone resin is formed so that an average film thickness may be set to 0.1-0.3 micrometer uniformly by processing the core material surface with a silicone coupling agent. The arithmetic average roughness Ra is equal to or greater than the average thickness of the coat resin layer, and the shape of the carrier is mainly controlled by the shape of the core material. For this reason, the shape of the carrier, specifically, Ra of the carrier and Ra of the core are substantially the same value. However, when a large amount of conductive filler is contained in order to reduce the resistance of the carrier, Ra of the carrier may be small.

The carrier of the present invention preferably has a magnetization of 40 to 90 Am ² / kg in a magnetic field of 1 kOe (10 ⁶ / 4π [A / m]). When this magnetization is less than 40 Am ² / kg, carriers may adhere to the image. On the other hand, when this magnetization exceeds 90 Am ² / kg, image blur may occur.

[Developer]
The carrier of the present invention can be used as a two-component developer by mixing with a toner.

  The toner used in the present invention is not particularly limited. For example, a toner containing a toner material such as a colorant, a charge control agent, and a release agent in a binder resin mainly composed of a thermoplastic resin. Can be used. In addition, an amorphous or spherical toner prepared by a toner production method such as a polymerization method or a granulation method can be used. Furthermore, both magnetic toner and non-magnetic toner can be used.

  As the toner binder resin, the following can be used alone or in combination. Styrene binder resin; homopolymers of styrene such as polystyrene and polyvinyltoluene, and substituted products thereof, styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-acrylic acid Methyl copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer Polymer, styrene-α-chloromethacrylic acid methyl copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene- Isoprene copolymer, styrene-male Acid copolymer, styrene - styrene copolymer and maleic acid ester copolymers, acrylic binders; polymethyl methacrylate, polybutyl methacrylate, and the like. Others, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or aliphatic hydrocarbon resin, aromatic Group petroleum resin, chlorinated paraffin, paraffin wax and the like. Among these, the toner used in the present invention preferably contains a polyester resin.

  A polyester resin is preferable because it can ensure stability during storage of the toner and can lower the melt viscosity as compared with a styrene resin or an acrylic resin. Such a polyester resin is not particularly limited, and can be obtained, for example, by a polycondensation reaction between an alcohol component and a carboxylic acid component.

  Examples of the alcohol component include diols such as polyethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-propylene glycol, neopentyl glycol, 1,4-butenediol, Etherified bisphenols such as 1,4-bis (hydroxymethyl) cyclohexane, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A, and the like. Divalent alcohol units substituted with saturated hydrocarbon groups, other divalent alcohol units, sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaesitol, dipentaes Tolu, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, tri Examples thereof include trihydric or higher alcohol monomers such as methylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

  Examples of the carboxylic acid component include monocarboxylic acids such as palmitic acid, stearic acid, and oleic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, and sebacic acid. , Malonic acid, divalent organic acid monomers in which they are substituted with a saturated or unsaturated hydrocarbon group having 3 to 22 carbon atoms, anhydrides of these acids, lower alkyl esters, and dimer from linolenic acid Acid, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butane Tricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane Tetra (methylene carboxyl) methane, 1,2,7,8-octane tetracarboxylic acid Enboru trimer acid, polyhydric carboxylic acid monomers such as trivalent or more anhydrides of these acids.

  Examples of the epoxy resin include a polycondensate of bisphenol A and epochlorohydrin. Specifically, for example, Epomic R362, R364, R365, R366, R367, R369 (above, manufactured by Mitsui Petrochemical Co., Ltd.), Epototo YD-011, YD-012, YD-014, YD-904, YD Commercially available products such as -017, (above, manufactured by Tohto Kasei Co., Ltd.) Epokote 1002, 1004, 1007 (above, manufactured by Shell Chemical Co., Ltd.).

  The colorant is not particularly limited, and carbon black, lamp black, iron black, ultramarine, nigrosine dye, aniline blue, phthalocyanine blue, Hansa Yellow G, rhodamine 6G lake, chalcoil blue, chrome yellow, quinacridone, benzidine yellow, Rose Bengal, triallylmethane dyes, monoazo dyes, disazo dyes, dyes and pigments can be used. These may be used alone or in combination of two or more.

  Further, the black toner can be made into a magnetic toner by containing a magnetic material. As the magnetic material, a ferromagnetic material such as iron or cobalt, magnetite, hematite, Li-based ferrite, Mn-Zn-based ferrite, Cu-Zn-based ferrite, Ni-Zn ferrite, Ba ferrite or the like may be used. it can.

  In order to sufficiently control the triboelectric chargeability of the toner, a charge control agent may be added to the toner. Specifically, for example, metal complex salts of monoazo dyes, nitrohumic acid and its salts, salicylic acid, naphthoic salts, metal complex amino compounds such as Co, Cr, Fe of dicarboxylic acids, quaternary ammonium compounds, organic dyes, etc. Can be made. In color toners other than black, it is preferable to use a metal salt of a white salicylic acid derivative.

  Although it does not specifically limit as a mold release agent, low molecular weight polypropylene, low molecular weight polyethylene, carnauba wax, microcrystalline wax, jojoba wax, rice wax, montanic acid wax, etc. are used alone or in combination of two or more. Can be used.

Further, in order to obtain a good image, an external additive may be added to the toner for the purpose of imparting sufficient fluidity to the toner. Generally, hydrophobized metal oxide fine particles and fine particles such as a lubricant are externally added as a fluidity improver. The external additive is not particularly limited, and for example, hydrophobized metal oxide fine particles, fine particles such as a lubricant, metal oxide, organic resin fine particles, metal soap and the like can be used. More specifically, for example, a fluororesin such as polytetrafluoroethylene, a lubricant such as zinc stearate, an abrasive such as cerium oxide or silicon carbide; for example, inorganic oxidation such as SiO ₂ or TiO ₂ having a hydrophobic surface. Examples thereof include fluidity imparting agents such as products; those known as anti-caking agents and surface-treated products thereof. Among these, it is preferable to use hydrophobic silica.

  Further, the weight average particle diameter of the toner is preferably 3.0 to 9.0 μm, and more preferably 3.0 to 6.0 μm. The weight average particle diameter of the toner can be measured using, for example, Coulter Multisizer II (manufactured by Coulter Counter).

  A toner can be added to the carrier of the present invention and used as an electrostatic latent image developer. Further, by applying the image forming apparatus as a replenishment developer and performing image formation while discharging excess developer in the developing device, an image having stable image quality can be formed over a long period of time. That is, by replacing the deteriorated carrier in the developing device and the undegraded carrier in the replenishment developer, the charge amount is kept stable and a stable image can be obtained. This method is particularly effective when printing a large image area. The main cause of the deterioration of the carrier at the time of printing a high image area is a decrease in the carrier charging ability due to the toner spent on the carrier. However, by using this method, the amount of carrier replenishment increases when the image area is high. For this reason, the frequency with which the deteriorated carrier is replaced is increased, and a stable image can be obtained over a long period of time.

  The mixing ratio of the carrier in the replenishment developer is usually 2 to 50 parts by mass of toner and preferably 5 to 12 parts by mass with respect to 1 part by mass of the carrier. When the amount of toner is less than 2 parts by mass with respect to 1 part by mass of the carrier, the amount of charge of the toner may increase because the carrier is excessively supplied and the carrier concentration in the developing device becomes too high. When the charge amount of the toner increases, the developing ability may decrease and the image density may decrease. Further, when the amount of toner exceeds 50 parts by mass with respect to 1 part by mass of the carrier, since the carrier ratio in the developer is small and the carrier is not replaced in the image forming apparatus, the effect of replacing the new carrier with respect to carrier deterioration is low. May be.

[Image Forming Apparatus and Image Forming Method]
Next, an example of an image forming apparatus of the present invention and an image forming method using the image forming apparatus will be described with reference to the drawings. These examples are intended to illustrate the invention and not to limit the invention.

  FIG. 2 is a schematic diagram relating to the developing unit of the image forming apparatus illustrating the present invention. The developing device 40 mainly includes a developing sleeve 41 as a developer carrying member, a developer accommodating member 42, a doctor blade 43 as a regulating member, a support case 44, and the like. Further, the developing device 40 is disposed so as to face the photosensitive drum 20 which is a latent image carrier.

  The support case 44 has an opening on the photosensitive drum 20 side, and a toner hopper 45 serving as a toner storage unit that stores the toner 21 is joined to the support case 44. A developer agitating mechanism 47 is provided in the developer accommodating portion 46 that adjoins the toner hopper 45 and accommodates the developer composed of the toner 21 and the carrier 23. The developer agitating mechanism 47 agitates the toner 21 and the carrier 23 and imparts friction / release charges to the toner particles.

  Inside the toner hopper 45, a toner agitator 48 and a toner replenishing mechanism 49 are disposed as toner supplying means, which are rotated by a driving means (not shown). The toner agitator 48 and the toner replenishing mechanism 49 send out the toner 21 in the toner hopper 45 toward the developer accommodating portion 46 while stirring.

  A developing sleeve 41 is disposed between the photosensitive drum 20 and the toner hopper 45. The developing sleeve 41, which is rotationally driven by a driving means (not shown), has a magnet (not shown) as a magnetic field generating means inside thereof in order to form a magnetic brush by the carrier 23. The magnet is disposed relative to the developing device 40 in a relative position.

  A doctor blade 43 is integrally attached to the developer accommodating member 42 on the side facing the side attached to the support case 44. For example, the doctor blade 43 is disposed with a certain gap between the tip thereof and the outer peripheral surface of the developing sleeve 41.

  By using the image forming apparatus exemplified above, for example, the image forming method of the present invention is performed as follows. The toner 21 delivered from the inside of the toner hopper 45 by the toner agitator 48 and the toner replenishing mechanism 49 is carried to the developer accommodating portion 46. Therefore, the developer is stirred by the developer stirring mechanism 47 to give a desired friction / peeling charge. The toner 21 is carried on the developing sleeve 41 as a developer together with the carrier particles 23 and conveyed to a position facing the outer peripheral surface of the photosensitive drum 20. Then, only the toner 21 is electrostatically coupled with the electrostatic latent image formed on the photosensitive drum 20, whereby a toner image is formed on the photosensitive drum 20.

  FIG. 3 is a schematic view of an image forming apparatus illustrating the present invention. Around the photosensitive drum 20, an image carrier charging member 32, an image exposure system 33, a developing device mechanism 40, a transfer mechanism 50, a cleaning mechanism 60, and a static elimination lamp 70 are mainly disposed. Further, the surface of the image carrier charging member 32 is in a non-contact state with respect to the surface of the photoreceptor 20 with a gap of about 0.2 mm, for example. When charging the photosensitive member 20 by the charging member 32, the charging member 32 is charged by an electric field in which an alternating current component is superimposed on a direct current component by a voltage applying unit (not shown). Accordingly, it is possible to reduce charging unevenness, which is effective. The image forming method including the developing method is performed by the following operation.

  The image forming method can be performed by a negative positive method. For example, the photoreceptor 20 having the organic photoconductive layer is neutralized by the neutralization lamp 70. Thereafter, a latent image is formed by laser light that is uniformly negatively charged by a charging member 32 such as a charging charger or a charging roller and is irradiated from a laser optical system 33. In the example of the present embodiment, the absolute value of the exposed portion potential is lower than the absolute value of the non-exposed portion potential.

  Laser light is emitted from a semiconductor laser, for example, and scans the surface of the photoconductor 20 in the direction of the rotation axis of the photoconductor 20 by a polygonal polygonal mirror (polygon) that rotates at high speed. The formed latent image is developed by the developer supplied on the developing device or the developing sleeve 41 to form a toner visible image. At the time of developing the latent image, a developing bias in which an appropriate voltage or an alternating voltage is superimposed on the developing sleeve 41 from a voltage applying mechanism (not shown) between the exposed portion and the non-exposed portion of the image carrier 20. Is applied.

  On the other hand, a transfer medium 80 such as paper is fed from a paper feed mechanism (not shown). Then, a pair of upper and lower registration rollers (not shown) synchronize with the leading edge of the image, and the sheet is fed between the photoconductor 20 and the transfer member 50 to transfer the toner image. At this time, it is preferable that a potential having a polarity opposite to the polarity of toner charging is applied to the transfer member 50 as a transfer bias. Thereafter, the transfer medium or the intermediate transfer medium 80 is separated from the photoreceptor 20, and a transfer image is obtained.

  The toner particles remaining on the photoreceptor 20 are collected into a toner collection chamber 62 in the cleaning mechanism 60 by a cleaning blade 61 as a cleaning member. The collected toner particles may be transported to the developing unit and / or the toner replenishing unit by a toner recycling unit (not shown) and reused.

  The image forming apparatus may be an apparatus in which a plurality of the developing devices described above are arranged, the toner images are sequentially transferred onto a transfer medium, then sent to a fixing mechanism, and the toner is fixed by heat or the like. Alternatively, a device may be used in which a plurality of toner images are once transferred onto an intermediate transfer medium, transferred to the transfer medium at once, and then fixed in the same manner.

  FIG. 4 shows a schematic diagram of another example of the image forming apparatus of the present invention. In this image forming apparatus, an electrophotographic developing method is used. The photoreceptor 20 is provided with at least a photosensitive layer on a conductive support. The photosensitive member 20 is driven by driving rollers 24a and 24b and charged by the charging roller 32; image exposure by the light source 33; development by the developing device 40; transfer using the charging device 50; exposure before cleaning by the light source 26; 64 and cleaning by the cleaning blade 61; and static elimination by the static elimination light source 70 are repeatedly performed. The photoreceptor 20 is irradiated with light for exposure before cleaning from the side of the support having translucency.

  FIG. 5 shows an example of the process cartridge of the present invention. The process cartridge of the present invention uses the carrier of the present invention, and includes at least a photosensitive member 20, a proximity brush-shaped contact charging unit 32, a developing device 40 that stores the developer of the present invention, and a cleaning blade 61 as a cleaning unit. The cleaning means having is integrally supported. The image forming apparatus main body is detachable. In the present invention, the above-described process cartridge can be configured to be detachable from a main body of an image forming apparatus such as a copying machine or a printer.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. “Parts” represents parts by mass.

[Conductive fine particle production example 1]
100 g of aluminum oxide (AKP-30 manufactured by Sumitomo Chemical Co., Ltd.) having an average primary particle size of 0.3 μm was dispersed in 1 liter of water, and the resulting suspension was heated to 70 ° C. To the obtained suspension, a solution obtained by dissolving 100 g of stannic chloride and 3 g of phosphorus pentoxide in 1 liter of 2N hydrochloric acid and 12% by mass of ammonia water were added so that the suspension had a pH of 7-8. It was dripped over 2 hours. After dropping, the suspension was filtered and washed, and the resulting cake was dried at 110 ° C. The powder obtained after drying was held at 500 ° C. for 1 hour in a nitrogen stream to obtain 37% of tin dioxide (conductive fine particles 1).

[Conductive fine particle production example 2]
100 g of aluminum oxide (HIT-70 manufactured by Sumitomo Chemical Co., Ltd.) having an average primary particle size of 0.15 μm was dispersed in 1 liter of water, and the resulting suspension was heated to 70 ° C. To the obtained suspension, a solution obtained by dissolving 100 g of stannic chloride and 3 g of phosphorus pentoxide in 1 liter of 2N hydrochloric acid and 12% by mass of aqueous ammonia was added so that the suspension had a pH of 7-8. It was added dropwise over time. After dropping, the suspension was filtered and washed, and the resulting cake was dried at 110 ° C. The powder obtained after drying was held in a nitrogen stream at 500 ° C. for 1 hour to obtain 37% of tin dioxide (conductive fine particles 2).

[Conductive fine particle production example 3]
100 g of aluminum oxide (Aeroxide AluC, Degussa) having an average primary particle size of 0.02 μm was dispersed in 1 liter of water, and the resulting suspension was heated to 70 ° C. To the obtained suspension, a solution obtained by dissolving 100 g of stannic chloride and 3 g of phosphorus pentoxide in 1 liter of 2N hydrochloric acid and 12% by mass of aqueous ammonia was added so that the suspension had a pH of 7-8. It was added dropwise over time. After dropping, the suspension was filtered and washed, and the resulting cake was dried at 110 ° C. The powder obtained after drying was held in a nitrogen stream at 500 ° C. for 1 hour to obtain 37% of tin dioxide (conductive fine particles 3).

[Conductive fine particle production example 4]
100 g of aluminum oxide (AKP-20 manufactured by Sumitomo Chemical Co., Ltd.) having an average primary particle size of 0.5 μm was dispersed in 1 liter of water, and the resulting suspension was heated to 70 ° C. To the obtained suspension, a solution obtained by dissolving 100 g of stannic chloride and 3 g of phosphorus pentoxide in 1 liter of 2N hydrochloric acid and 12% by mass of aqueous ammonia was added so that the suspension had a pH of 7-8. It was added dropwise over time. After dropping, the suspension was filtered and washed, and the resulting cake was dried at 110 ° C. The powder obtained after drying was held at 500 ° C. for 1 hour in a nitrogen stream to obtain 37% of tin dioxide (conductive fine particles 4).

[Conductive fine particle production example 5]
100 g of aluminum oxide (AKP-30 manufactured by Sumitomo Chemical Co., Ltd.) having an average primary particle size of 0.3 μm was defined as (conductive fine particles 5). That is, (conductive fine particle 5) does not contain tin dioxide.

[Core Material Production Example 1]
MnCO ₃ , Mg (OH) ₂ and Fe ₂ O ₃ powder were weighed and mixed to obtain a mixed powder. The obtained mixed powder was calcined in an air atmosphere for 3 hours in an electric furnace heated to 900 ° C. The obtained calcined product was pulverized after cooling to obtain a powder having a particle size of about 7 μm. A 1 wt% dispersant and water were added to the obtained powder to form a slurry, and the obtained slurry was supplied to a spray dryer and granulated to obtain a granulated product having an average particle size of about 40 μm. The obtained granulated material was loaded into a firing furnace and fired at 1250 ° C. for 5 hours in a nitrogen atmosphere. The obtained fired product was pulverized with a pulverizer, and the particle size was adjusted by sieving to obtain spherical particles having a volume average particle size of about 35 μm. The obtained spherical particles are defined as (Core 1). Was subjected to component analysis of the core 1, MnO (46.2mol%), MgO (0.7mol%), was Fe 2 O 3 (53mol%) .

  The core material 1 had a shape factor SF-1 of 140, a shape factor SF-2 of 145, and an arithmetic average roughness Ra of 0.7 μm.

  The shape factor of the core material is magnified 300 times using FE-SEM (S-800, manufactured by Hitachi, Ltd.), 100 particles are randomly sampled, and the image information is sent to, for example, Nireco via the interface. It is obtained by introducing the image analysis apparatus (Luzex AP) manufactured by the company and performing analysis. At that time, SF-1 is calculated by the following formulas (1) and (2).

SF-1 = (L ² / A) × (π / 4) × 100 (Expression (1))
SF-2 = (P ² / A) × (1 / 4π) × 100 (Expression (2))
In the formula, L is the absolute maximum length of the particle (the length of the circumscribed circle), P is the peripheral length of the particle, and A is the projected area of the particle.

[Core material production example 2]
A calcined product was obtained in the same manner as in Core Material Production Example 1. The obtained calcined product was pulverized after cooling to obtain a powder having a particle size of about 1 μm. The subsequent steps were performed in the same manner as in Core Material Production Example 1, and the resulting spherical particles were used as Core Material 2.

  The shape factor SF-1 of the core material 2 was 130, the shape factor SF-2 was 128, and the arithmetic average roughness Ra was 0.45 μm.

[Core Material Production Example 3]
MnCO ₃ , Mg (OH) ₂ , Fe ₂ O ₃ powder and SrCO ₃ were weighed and mixed to obtain a mixed powder. The obtained mixed powder was calcined in an air atmosphere for 1 hour in an electric furnace heated to 850 ° C. The obtained calcined product was cooled and pulverized to obtain a powder having a particle size of about 3 μm or less. A 1 wt% dispersant and water were added to the obtained powder to form a slurry, and the obtained slurry was supplied to a spray dryer and granulated to obtain a granulated product having an average particle size of about 40 μm. The obtained granulated material was loaded into a firing furnace and fired at 1120 ° C. for 4 hours in a nitrogen atmosphere. The obtained fired product was pulverized with a pulverizer, and the particle size was adjusted by sieving to obtain spherical particles having a volume average particle size of about 35 μm. The obtained spherical particles are defined as (Core 3). Was subjected to component analysis of the core _{3, MnO (40.0mol%),} MgO (10.0mol%), Fe 2 O 3 (50mol%), was SrO (0.4mol%).

  The core material 3 had a shape factor SF-1 of 145, a shape factor SF-2 of 155, and an arithmetic average roughness Ra of 0.85 μm.

[Core Material Production Example 4]
A granulated product having an average particle size of about 40 μm was obtained in the same manner as in Core Material Production Example 3. The obtained granulated material was loaded into a firing furnace and fired at 1180 ° C. for 4 hours in a nitrogen atmosphere. The obtained fired product was pulverized with a pulverizer, and the particle size was adjusted by sieving to obtain spherical particles having a volume average particle size of about 35 μm. Let the obtained spherical particle be (core material 4).

  The shape factor SF-1 of the core material 4 was 135, the shape factor SF-2 was 132, and the arithmetic average roughness Ra was 0.63 μm.

[Core Material Production Example 5]
A granulated product having an average particle size of about 40 μm was obtained in the same manner as in Core Material Production Example 3. The obtained granulated product was loaded into a firing furnace and fired at 1080 ° C. for 4 hours in a nitrogen atmosphere. The obtained fired product was pulverized with a pulverizer, and the particle size was adjusted by sieving to obtain spherical particles having a volume average particle size of about 35 μm. Let the obtained spherical particle be (core material 5).

  The shape factor SF-1 of the core material 5 was 150, the shape factor SF-2 was 165, and the arithmetic average roughness Ra was 1.03 μm.

[Carrier Production Example 1]
A 0.3% by mass aqueous solution of 3- (2-aminoethyl) aminopropyltrimethoxysilane (Z-6020 manufactured by Toray Dow Corning Co., Ltd.) was spray-dried onto (core material 4) using a fluidized bed type coating apparatus. Thereby, 0.1 mass% of 3- (2-aminoethyl) aminopropyltrimethoxysilane with respect to the core material weight was applied (silane coupling coated core material 1). During coating and drying, the temperature was controlled at 90 ° C.

  A resin solution having a solid content of 10 wt% was prepared by diluting 100 parts of silicone resin (SR2411 solid content 20 wt%, manufactured by Tore Dow Corning Silicone) and 40 parts (conductive fine particles 1) with toluene. The obtained resin solution was applied to (silane coupling-coated core material 1) using a fluidized bed coating apparatus and dried so that the average film thickness on the core material surface was 0.3 μm. Coating and drying were performed while controlling at 70 ° C.

  The obtained solid was baked at 230 ° C./2 hours in an electric furnace to obtain (Carrier 1). The amount of conductive fine particles of the carrier 1 was 6 wt% with respect to the weight of the core material.

[Carrier Production Example 2]
A carrier was produced in the same process as in Carrier Production Example 1 except that the average film thickness of the resin solution application in Carrier Production Example 1 was changed from 0.3 μm to 0.1 μm, and (Carrier 2) was obtained.

[Carrier Production Example 3]
A carrier was produced in the same process as in Carrier Production Example 1 except that the average film thickness of the resin solution application in Carrier Production Example 1 was changed from 0.3 μm to 0.4 μm, and (Carrier 3) was obtained.

[Carrier Production Example 4]
Except for changing (conductive fine particle 1) used in carrier production example 1 to (conductive fine particle 2) and changing the average film thickness of the resin solution coating from 0.3 μm to 0.1 μm, A carrier was produced in the same process to obtain (Carrier 4).

[Carrier Production Example 5]
A carrier was produced in the same process as in Carrier Production Example 1 except that (Conductive Fine Particle 1) used in Carrier Production Example 1 was changed to (Conductive Fine Particle 3) to obtain (Carrier 5).

[Carrier Production Example 6]
The carrier production example 1 is the same as the carrier production example 1 except that the (conductive fine particle 1) used in the carrier production example 1 is changed to (conductive fine particle 4) and the average film thickness of the resin solution coating is changed from 0.3 μm to 0.1 μm. A carrier was produced in the same process to obtain (Carrier 6).

[Carrier Production Example 7]
A carrier was produced in the same process as in Carrier Production Example 1 except that (Conductive Fine Particle 1) used in Carrier Production Example 1 was changed to (Conductive Fine Particle 5) to obtain (Carrier 7).

[Carrier Production Example 8]
A carrier was produced in the same process as in Carrier Production Example 1 except that (Core 4) used in Carrier Production Example 1 was changed to (Core 1) to obtain (Carrier 8).

[Carrier Production Example 9]
A carrier was produced in the same process as in Carrier Production Example 1 except that (Core 4) used in Carrier Production Example 1 was changed to (Core 3) to obtain (Carrier 9).

[Carrier Production Example 10]
A carrier was produced in the same process as in Carrier Production Example 1 except that 100 parts of the silicone resin (SR2411) used in Carrier Production Example 1 was changed to 80 parts of the resin synthesized in the following Resin Synthesis Example 1. 10) was obtained.

[Resin synthesis example 1]
300 g of toluene was charged into a flask equipped with a stirrer, and the temperature was raised to 90 ° C. under a nitrogen gas stream. Next, in this flask, 3-methacryloxypropyltris (trimethylsiloxy) silane (CH ₂ = CMe—COO—C ₃ H ₆ —Si (OSiMe ₃ ) ₃ , where Me is a methyl group), 200 Mmol, Silaplane TM-0701T, manufactured by Chisso Corporation) 84.4 g, 3-methacryloxypropyltrimethoxysilane 37.2 g (150 mmol), methyl methacrylate 65.0 g (650 mmol) and 2,2′-azobis A mixture of 0.58 g (3 mmol) of 2-methylbutyronitrile was added dropwise over 1 hour. After completion of the dropwise addition, a solution prepared by dissolving 0.06 g (0.3 mmol) of 2,2′-azobis-2-methylbutyronitrile in 15 g of toluene was added and mixed at 90 to 100 ° C. for 3 hours for radical copolymerization. As a result, a methacrylic copolymer was obtained.

The weight average molecular weight of the obtained methacrylic copolymer was 34,000. Subsequently, it diluted with toluene so that the non volatile matter of this methacrylic copolymer solution might be 25 mass%. The viscosity of the obtained copolymer solution was 8.7 mm ² / s, and the specific gravity was 0.91.

  The weight average molecular weight was determined in terms of standard polystyrene using gel permeation chromatography. The viscosity was measured at 25 ° C. according to JIS-K2283. The nonvolatile content was calculated according to the following formula by weighing 1 g of the composition in an aluminum dish and measuring the weight after heating at 150 ° C. for 1 hour.

Nonvolatile content (%) = (weight after heating × 100) / weight before heating [Carrier Production Example 11]
A carrier was produced in the same process as in Carrier Production Example 1 except that 0.1% by weight of 3- (2-aminoethyl) aminopropyltrimethoxysilane applied in Carrier Production Example 1 was not applied. Carrier 11) was obtained.

[Carrier Production Example 12]
In carrier production example 11, a silicone resin (SR2411 Toray Dow Corning Silicone Co., Ltd.) (100 parts) and 40 parts of (conductive fine particles 1) diluted with toluene were mixed with a resin solution having a solid content of 10 wt%. Dow Corning Silicone Co., Ltd. (100 parts), (conductive fine particles 1) 40 parts and 3- (2-aminoethyl) aminopropyltrimethoxysilane (Toray Dow Corning Z-6020) 1 part diluted with toluene A carrier was produced under the same conditions as in Carrier Production Example 11 except that the resin solution was changed to a 10 wt% resin solution (Carrier 12).

[Carrier Production Example 13]
A carrier was produced in the same process as in Carrier Production Example 1 except that (Core 4) in Carrier Production Example 1 was changed to (Core 2) to obtain (Carrier 13).

[Carrier Production Example 14]
A carrier was produced in the same process as in Carrier Production Example 1 except that the average film thickness of the resin solution application in Carrier Production Example 1 was changed from 0.3 μm to 0.7 μm, and (Carrier 14) was obtained.

[Carrier Production Example 15]
A carrier was produced in the same process as in Carrier Production Example 1 except that (Core 4) was changed to (Core 5) in Carrier Production Example 1, and (Carrier 15) was obtained.

  Table 1 shows a correspondence table of the core material, the coat resin, and the conductive fine particle preparation examples for the carriers of the examples and comparative examples. Table 1 also shows the physical properties and evaluation results of carriers and developers obtained in the respective examples and comparative examples.

[Evaluation of career]
Hereafter, the evaluation method of the characteristic is shown about the carrier of this invention.

<< Weight average particle diameter of core material >>
The particle size distribution of the core material was measured using a Microtrac particle size analyzer (model HRA9320-X100: manufactured by Honeywell). The measurement conditions are as follows.

Particle size range: 100-8 μm,
Channel length (channel width): 2 μm
Number of channels: 46
Refractive index: 2.42.

<< Average film thickness of coated resin >>
The thickness h (μm) of the coated carrier of the manufactured carrier is measured by observing the cross section of the carrier using a transmission electron microscope (TEM (2,000 times magnification)) and measuring the thickness of the coated resin layer covering the carrier surface. Specifically, the distance from the surface of the core material to the surface of the coat layer at any 50 points in the carrier cross section was measured, and the average of the measured values was obtained to obtain the thickness h (μm).

<Dispersion state of conductive fine particles>
Using a scanning electron microscope (SEM (2,000 times magnification)), the cross-section of any 10 carriers was observed to evaluate the dispersion state of the convex portions of the conductive fine particles on the carrier surface layer. It is as follows.
◯: Convex portions derived from conductive fine particles are uniformly present on the carrier surface layer.
X: The presence of the convex portions derived from the conductive fine particles is biased, and there are portions where the convex portions are connected.

[Production of toner]
100 parts of polyester resin (weight average molecular weight (Mw) 18,000, number average molecular weight (Mn) 4000, glass transition point (Tg) 59 ° C., softening point 120 ° C.),
Mold release agent: 5 parts carnauba wax,
10 parts of carbon black (# 44, manufactured by Mitsubishi Chemical Corporation)
4 parts of fluorine-containing quaternary ammonium salt,
Were mixed with a Henschel mixer, melt kneaded with a twin screw extruder, and the kneaded product was rolled and cooled. After standing to cool, it was coarsely pulverized with a cutter mill, and then finely pulverized with a jet airflow fine pulverizer. Further, the toner was classified using an air classifier to obtain toner base particles having a weight average particle diameter of 7.4 μm.

To 100 parts of the obtained toner base particles, 1.0 part of hydrophobic silica fine particles (R972: manufactured by Nippon Aerosil Co., Ltd.) are added and mixed with a Henschel mixer to obtain a toner having a weight average particle diameter of 7.2 μm (Toner 1). Got.

[Production of developer]
7.0 parts of (Toner 1) was added to 93 parts of the carrier obtained in each Example and Comparative Example, and stirred for 20 minutes with a ball mill to obtain Developer 1 to Developer 15.

  In Example 8, instead of (Toner 1), a premix toner obtained by mixing 90 parts of toner and 10 parts of (Carrier 1) was used, and excess developer was discharged, as in Example 1. went.

[Developer evaluation]
After initial image formation using the developers obtained in each of the examples and comparative examples, the developer was mounted on an ImageColor 4000 (manufactured by Ricoh Co., Ltd.) and stirred for 10 minutes in a single color mode. Thereafter, 100,000 sheets were run using a chart with an image area of 7%, and the evaluation contents shown below were evaluated after the test was completed.

Development conditions are as follows.
Development gap (photosensitive member-developing sleeve): 0.3 mm,
Doctor gap (developing sleeve-doctor): 0.65 mm,
Photoconductor linear velocity: 200 mm / sec,
(Developing sleeve linear velocity) / (photosensitive member linear velocity): 1.80,
Writing density: 600 dpi
Charging potential (Vd): -600V
Potential after exposure of the portion corresponding to the image portion (solid document): −100V,
Developing bias: DC −500 V / AC bias component: 2 kHz, −100 V to −900 V, 50% duty.

  Evaluation was carried out on transfer paper, but carrier adhesion was observed by transferring the state after development and before transfer onto the adhesive tape from the photoreceptor.

  In addition, about the result of the following evaluation item, it has shown according to the above-mentioned Table 1.

<Film peeling>
The developer 6g obtained in Examples and Comparative Examples and the developer 6g after running 100,000 sheets were placed in a conductor container (cage) having metal meshes at both ends. The mesh (stainless steel) has an opening of an intermediate particle size between the toner and the carrier (opening 20 μm), and is set so that the toner passes between the meshes. Next, compressed nitrogen gas (1 kgf / cm ² ) was blown from the nozzle for 60 seconds to cause the toner to jump out of the gauge. This leaves a carrier having the opposite polarity to the charge of the toner in the cage. After recovering the carrier and extracting the toner component with methyl ethyl ketone, the cross section of 10 arbitrarily selected carriers was observed using a scanning electron microscope (SEM (magnification 2000 times)). In the evaluation, the presence degree of the coat resin peeling portion (= core material exposed portion) on the carrier surface layer was classified as shown below.
○: Coated resin peeling part is not seen,
(Triangle | delta): Coated resin peeling part is confirmed less than ten places per carrier particle,
X: The coating resin peeling part is confirmed 10 or more places per carrier particle,
It was.

<Amount of spent toner>
The developer 6g obtained in Examples and Comparative Examples and the developer 6g after running 100,000 sheets were placed in a conductor container (cage) having metal meshes at both ends. The mesh (stainless steel) has an opening of an intermediate particle size between the toner and the carrier (opening 20 μm), and is set so that the toner passes between the meshes. Next, compressed nitrogen gas (1 kgf / cm ² ) was blown from the nozzle for 60 seconds to cause the toner to jump out of the gauge. This leaves a carrier having the opposite polarity to the charge of the toner in the cage. The carrier was recovered, and the toner component was extracted with methyl ethyl ketone to obtain the spent toner amount (expressed in mass% with respect to the carrier weight). The evaluation criteria are as follows.
0 or more and less than 0.03 mass%: ◎,
0.03 mass% or more to less than 0.07 mass%: ○,
0.07 mass% or more to less than 0.15 mass%: Δ,
0.15% by mass or more: ×,
It was.

<Fluctuation in pumping volume>
The fluctuation of the developer pumping amount was calculated and evaluated by the following formula.
Fluctuation rate of developer pumping amount (%) = {(initial developer pumping amount (mg / cm ² ) −developer pumping amount after running 100,000 sheets (mg / cm ² )) / initial developer pumping amount (Mg / cm ² )} × 100.
The evaluation criteria are as follows.
Less than ± 5%: ◎,
± 5 or more to less than ± 10%: ○,
± 10 or more to less than ± 20%: Δ
± 20% or more: ×,
It was.

<Carrier adhesion>
Even if carrier adhesion occurs on the photoconductor, only a part of the carrier is transferred to the paper, and thus evaluation was made by the following method. The number of carriers adhering to the solid image (30 mm × 30 mm) of ImagioColor 4000 under the above-described development conditions was counted on the photoconductor to evaluate the solid carrier adhesion.
Very good: ◎,
Good: ○,
Available: △,
Defect: ×,
It was.

《Soil dirt》
The dirt on the background on the image was visually observed to evaluate the dirt.
Very good: ◎,
Good: ○,
Available: △,
Defect: ×,
It was.

<Image density reduction>
The center of a solid portion of 30 mm × 30 mm under the above developing conditions was measured at five locations with a spectrocolorimetric densitometer (X-Rite 938, manufactured by X-Rite), and an average value was obtained.
1.55 or more: ◎,
1.50 or more and less than 1.55: ○,
1.45 or more and less than 1.50: Δ,
Less than 1.45: x,
It was.

《Image tip density abnormality (ghost image)》
FIG. 6 shows an example of a test chart using the developer of the present invention. A developer is set in a commercially available digital full-color printer (RICOH Pro C901 manufactured by Ricoh Co., Ltd.), and a test shown in FIG. 6 is performed after outputting a character chart (image size: about 2 mm × 2 mm) of 8% image area to 100K sheets. The chart was printed. The evaluation is based on X-Rite 938 (manufactured by X-Rite Co.) for the density difference between the area for one round of the sleeve (a in FIG. 6) and the area after one round (b in FIG. 6). Three locations were measured, and the average density difference was taken as ΔID.

The evaluation criteria are as follows.
◎: Very good, ○: Good, Δ: Acceptable, ×: Unusable level for practical use, ◎, ○, △ were accepted and x was rejected.
0.01 ≦ ΔID ◎,
0.01 <ΔID ≦ 0.03 ○,
0.03 <ΔID ≦ 0.06 Δ,
0.06 <ΔID ×,
It was. .

DESCRIPTION OF SYMBOLS 1 Coat layer 2 Core material 3 Core material exposed part top view 11 Cell 12a Electrode 12b Electrode 13 Carrier 20 Photoconductor drum 21 Toner 23 Carrier 24a Drive roller 24b Drive roller 26 Pre-cleaning exposure light source 32 Image carrier charging member 33 Image exposure system 40 developing device 41 developing sleeve 42 developer accommodating member 43 doctor blade 44 support case 45 toner hopper 46 developer accommodating portion 47 developer agitating mechanism 48 toner agitator 49 toner replenishing mechanism 50 transfer mechanism 60 cleaning mechanism 61 cleaning blade 62 toner recovery chamber 64 Brush-like cleaning means 70 Static elimination lamp 80 Intermediate transfer medium

Japanese Patent Laid-Open No. 3-160463 JP 2007-333886 A

Claims (12)

  A carrier in which the surface of a core material is coated with a silane coupling agent and then coated with a coating resin layer containing a silicone resin containing conductive fine particles, and the arithmetic average roughness Ra of the core material is 0.6 to 0.00. A carrier having a thickness of 9 μm and an arithmetic average roughness Ra equal to or greater than an average thickness of the coat resin layer.   The carrier according to claim 1, wherein the conductive fine particles have an average particle size of 0.15 to 0.5 μm.   The carrier according to claim 1, wherein the conductive fine particles have a base and a conductive coating layer, the base includes alumina, and the conductive coating layer includes tin dioxide.   The carrier according to any one of claims 1 to 3, wherein the coat resin has an average film thickness of 0.1 µm to 0.3 µm.   The carrier according to any one of claims 1 to 4, wherein the silane coupling agent contains an amino group. The silicone resin is
(Where
R ¹ : a hydrogen atom or a methyl group,
_{(CH 2) m:} methylene group having 1 to 8 carbon atoms, an ethylene group, a propylene group and an alkylene group such as butylene group,
R ² : an aliphatic hydrocarbon group having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, a propyl group and a butyl group, and a plurality of R ² may be the same or different.
X = 10 to 90 mol%. )
as well as
(Where
R ⁴ : hydrogen atom or methyl group,
(CH ₂ ) _n : alkylene group such as methylene group having 1 to 8 carbon atoms, ethylene group, propylene group and butylene group,
R ⁵ : an aliphatic hydrocarbon group such as a methyl group, an ethyl group, a propyl group and a butyl group having 1 to 4 carbon atoms, and a plurality of R ⁵ may be the same or different,
R ⁶ : C 1-8 alkyl group (methyl group, ethyl group, propyl group, butyl group, etc.) or C 1-4 alkoxy group (methoxy group, ethoxy group, propoxy group, butoxy group), Y = 10 to 90 mol%. )
The carrier as described in any one of Claims 1 thru | or 5 containing resin obtained by heat-processing the copolymer containing these repeating units. The carrier according to claim 1, wherein the conductive fine particles are 2 to 8 mass% with respect to the core material.   The carrier according to claim 1, wherein the core material has a weight average particle diameter of 20 to 50 μm.   A two-component developer comprising the carrier according to any one of claims 1 to 8 and a toner.   An electrostatic latent image carrier, a charging member for charging the surface of the photosensitive member, and development for developing the electrostatic latent image formed on the electrostatic latent image carrier using the developer according to claim 9. And a process cartridge having a cleaning member for cleaning the electrostatic latent image carrier.   A step of forming an electrostatic latent image on a photoreceptor, a step of developing the electrostatic latent image using the developer according to claim 9 to form a toner image, and transferring the toner image to a recording medium And a step of fixing the toner image transferred to the recording medium.   A replenishment developer comprising the carrier according to claim 1 and a toner.