JP5034815B2 - Image forming method and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming method and an image forming apparatus using an electrophotographic system.

  In recent electrophotographic image forming processes, particularly color image forming, a primary image developed on a photoconductor is temporarily transferred onto an intermediate transfer body in order to realize high-quality color reproducibility by color superposition, An image forming process for transferring and fixing to a final printing medium is widely used (Patent Documents 1 to 3).

  As for the toner, in order to achieve a high resolution image, it is the mainstream to use a toner having a small diameter of less than 8.0 μm formed by a polymerization method. The toner having a small particle diameter has a large surface area relative to the mass, has a strong tendency to adhere to the surface of the photoreceptor or the intermediate transfer body, and has a relatively high tendency to lower the transfer rate. Therefore, as a measure for reducing the adhesiveness of the toner surface and improving the transfer efficiency, a method of adding an external additive to the toner and treating the toner surface with the external additive (metal oxide fine particles) is widely used.

However, in the process using an intermediate transfer body, sufficient transfer efficiency and image quality cannot be obtained only with the metal oxide treatment on the toner surface. Achieves the desired transfer efficiency and image quality by reducing the direct contact between the photoconductor surface and the toner by forming a very thin metal soap film on the photoconductor and intermediate transfer surface by adding soap. is doing.
JP 2000-206801 A JP 2006-259581 A JP 2003-165857 A

  As described above, when metal soap and metal oxide, which are external additives of toner, coexist on the surface of the photoreceptor, cometary deposits are likely to be generated on the surface of the photoreceptor, coupled with the pressing force of the intermediate transfer body. all right. In particular, when the number of printed sheets increases and liberation of the external additive (metal oxide) in the developer progresses, the size of the comet-like deposit increases and appears as an image defect on the final image.

  Comet-like deposits do not pose a serious problem when only one of metal oxide and metal soap is present, and can be said to be a special problem that occurs in a system in which both compounds are present.

  Generation of comet-like deposits is suppressed as the photoconductor is worn when the amount of wear on the photoconductor is large. However, in the case of a photoconductor with a protective layer with excellent wear resistance and low photoconductor wear for the purpose of prolonging the life of the photoconductor, the amount of wear is much less than that of conventional photoconductors. A large number of large comet-like deposits are generated.

  The present invention has been made to solve the above problems.

  That is, the object of the present invention is to prevent the formation of comet-like deposits on the surface of a photoreceptor even when used for a long period of time using a small particle size toner. An object of the present invention is to provide an image forming method and an image forming apparatus to which the image forming method is applied so that no flaws on the body surface occur.

  As a result of intensive studies to suppress the occurrence of the above-mentioned comet-like deposits and image defects, the present inventors have found that the object can be achieved by using the following configuration.

(1)
An image forming method comprising a step of transferring a toner developed on a photosensitive member in which at least a photosensitive layer and a protective layer are laminated in this order on a conductive support to an intermediate transfer member, wherein the toner comprises at least a metal oxide and a metal soap And a protective layer containing at least a component obtained by reacting a photocurable acrylic compound having at least an acryloyl group or a methacryloyl group , and titanium oxide particles. Image forming method.

(2)
The image forming method according to (1), wherein the number of acryloyl groups or methacryloyl groups of the photocurable acrylic compound is 3 or more.

(3)
The image forming method according to (1) or (2), wherein the photocurable acrylic compound has a curable reactive group equivalent of 1000 or less.

(4)
An image forming apparatus, wherein an image is formed by the image forming method according to any one of (1) to (3).

  The reason why the comet-like deposits are not generated when the protective layer of the electrophotographic photosensitive member contains at least a component obtained by reacting a curable compound and titanium oxide particles is not clear. The present inventors have determined that the component obtained by reacting with the curable compound has a deformation behavior due to the external additive of the toner sandwiched between the photosensitive member and the intermediate transfer member, and a conventional protective layer such as a thermoplastic resin. It is presumed that the difference is that the titanium oxide particles present in the vicinity of the surface of the photoreceptor greatly reduce the adhesion of the photoreceptor surface to the metal soap or metal oxide in the developer.

  In addition, although various particles having the same particle diameter were also examined, generation of comet-like deposits could not be solved except for titanium oxide particles. From this, it is clear that the effect is not dependent on the physical shape of the surface, which can be easily conceived by those skilled in the art.

  According to the present invention, no comet-like deposits are generated on the surface of the photoreceptor even when used for a long period of time with a small particle size toner. An image forming method and an image forming apparatus to which the image forming method is applied can be provided.

  Hereinafter, the present invention will be described in detail.

  In the structure of the present invention, a protective layer is formed for the purpose of improving the mechanical strength and printing durability of an electrophotographic photosensitive member (hereinafter also simply referred to as a photosensitive member) and protecting the surface of the photosensitive layer. . The protective layer is formed by curing at least a component obtained by reacting a curable compound, and contains the titanium oxide particles, whereby the object of the present invention can be achieved.

[Photosensitive layer structure]
The photoreceptor of the present invention is obtained by sequentially laminating at least a photosensitive layer and a protective layer on a conductive support. The layer structure is not particularly limited, and specifically, as shown below. A layer structure can be mentioned.

1) A layer structure in which a charge generation layer, a charge transport layer, and a protective layer are sequentially laminated as a photosensitive layer on a conductive support.
2) A layer structure in which a single layer containing a charge transport material and a charge generation material as a photosensitive layer and a protective layer are sequentially laminated on a conductive support.
3) Layer structure in which a charge generation layer, a charge transport layer, and a protective layer are sequentially laminated as an intermediate layer and a photosensitive layer on a conductive support.
4) A layer structure in which an intermediate layer, a single layer containing a charge transport material and a charge generation material as a photosensitive layer, and a protective layer are sequentially laminated on a conductive support.

  The photoreceptor of the present invention may have any of the above-described layer structures, but among these, those prepared by providing an intermediate layer, a charge generation layer, a charge transport layer, and a protective layer on a conductive support are preferable. .

  The intermediate layer, charge generation layer, charge transport layer, and protective layer can be applied by dip coating, spray coating, spinner coating, bead coating, blade coating, beam coating, slide hopper, etc. Can be used.

[Protective layer]
The protective layer of the present invention has a constitution in which at least a component obtained by reacting a curable compound and titanium oxide particles are contained in the surface layer.

(Curable compound)
The curable compound of the present invention is preferably a monomer that is polymerized (cured) by irradiation with actinic rays such as ultraviolet rays or electron beams and becomes a resin generally used as a binder resin for a photoreceptor, such as polystyrene and polyacrylate. Styrene monomers, acrylic monomers, methacrylic monomers, vinyl toluene monomers, vinyl acetate monomers, and N-vinyl pyrrolidone monomers are preferred.

  Among these, a photocurable acrylic compound having an acryloyl group or a methacryloyl group (hereinafter also referred to as an acrylic compound) is particularly preferable because it can be cured in a small amount of light or in a short time.

  In the present invention, these monomers may be used alone or in combination.

  Examples of photocurable acrylic compounds (hereinafter also referred to as acrylic compounds) are shown below.

In the present invention, the acrylic compound is a compound having an acryloyl group (CH ₂ ═CHCO—) or a methacryloyl group (CH ₂ ═CCH ₃ CO—). In addition, the number of Ac groups (the number of acryloyl groups) described below represents the number of acryloyl groups or methacryloyl groups.

  However, in the above, R and R 'are respectively shown below.

  KAYARAD MANDA (manufactured by Nippon Kayaku Co., Ltd., molecular weight 312, bifunctional acrylic monomer): B-1.

  Various reactive oligomers can also be used. For example, an epoxy acrylate oligomer, a urethane acrylate oligomer, a polyester acrylate oligomer, or an unsaturated polyester resin can be used. Specific examples are as follows.

KAYARAD DPCA120 (manufactured by Nippon Kayaku Co., Ltd., molecular weight 1947, hexaacrylate of hexafunctional dipentaerythritol derivative): B-2
E8402 (Daicel Cytec Co., Ltd., molecular weight 1000, bifunctional urethane acrylate): B-3.

  In the present invention, the curable compound preferably has 3 or more functional groups, particularly preferably 5 or more. Further, the equivalent amount of the curable reactive group, that is, “curable compound molecular weight / number of functional groups” is preferably 1000 or less, and particularly preferably 500 or less. As a result, the crosslink density is increased and the wear resistance of the photoreceptor is improved. If the value is larger than this, a problem may occur in the high durability of the photoreceptor.

  In the present invention, two or more kinds of curable compounds having different curable reactive group equivalents may be mixed and used.

(Titanium oxide particles)
The titanium oxide particles used in the present invention are not particularly limited, but the crystal type system is preferably anatase or rutile.

  Further, the titanium oxide particles used in the present invention are preferably those produced by a known method such as a gas phase method, a chlorine method, a sulfuric acid method, a plasma method or the like.

  The number average primary particle size of the titanium oxide particles used in the present invention is preferably in the range of 1 to 300 nm. Especially preferably, it is 3-100 nm. When the particle size is small, the wear resistance is not sufficient, and when the particle size is large, writing light may be scattered, or the particles may hinder photocuring and the wear resistance may be insufficient.

  The ratio of the titanium oxide particles in the protective layer is 1 to 200 parts by mass, particularly preferably 10 to 80 parts by mass with respect to 100 parts by mass of the curable acrylic compound.

  In addition to the curable compound and titanium oxide particles, the protective layer can be applied with a coating solution containing a polymerization initiator, a filler, lubricant particles, an antioxidant, and the like, if necessary, and reacted to form a cured film. .

  When the curable compound of the present invention is reacted, a method of reacting by electron beam cleavage, a method of reacting with light and heat by adding a radical polymerization initiator, and the like are used. As the polymerization initiator, either a photopolymerization initiator or a thermal polymerization initiator can be used. Further, both light and heat initiators can be used in combination.

  Examples of the polymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4- (2-hydroxyethoxy) phenyl- (2- Hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1,2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-methyl Acetophenone-based or ketal-based photopolymerization initiators such as 2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, benzoin, Benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, Benzoin ether photopolymerization initiators such as benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether, acrylated benzophenone, 1 Benzophenone photopolymerization initiators such as 1,4-benzoylbenzene, thioxanthone photopolymerization such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone Initiators are mentioned.

  Other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine Examples thereof include oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, acridine compound, triazine compound, and imidazole compound. Moreover, what has a photopolymerization acceleration effect can also be used individually or in combination with the said photoinitiator. Examples include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4′-dimethylaminobenzophenone, and the like.

  These polymerization initiators may be used alone or in combination of two or more. Content of a polymerization initiator is 0.1-20 mass parts with respect to 100 mass parts of an acryl-type compound, Preferably it is 0.5-10 mass parts.

  Various fillers can also be added to improve the film strength and adjust the resistance. As fillers, various metal oxides such as silica, alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide and bismuth oxide, tin-doped indium oxide, antimony-doped tin oxide and zirconium oxide, etc. Fine particles can be used. You may use these metal oxides 1 type or in mixture of 2 or more types. When two or more types are mixed, they may take the form of a solid solution or fusion. The filler preferably has a number average primary particle size of 1 to 300 nm. In particular, it is preferably 3 to 100 nm. The ratio of the filler in a protective layer is 1-100 mass parts with respect to 100 mass parts of acrylic compounds, Most preferably, it is 10-80 mass parts.

  In the protective layer used in the present invention, various surface treatments can be applied to the filler for the purpose of improving the dispersibility and smoothness of the filler. Examples of the surface treatment agent include various inorganic treatments, treatments with silicon compounds, fluorine-containing silane coupling agents, fluorine-modified silicone oils, fluorine-based surfactants, fluorine-based graft polymers, and the like.

  The protective layer of the present invention can further contain various charge transport materials.

  Various lubricant particles can be added to the protective layer used in the present invention. For example, fluorine atom-containing resin particles can be added. Fluorine atom-containing resin particles include tetrafluoroethylene resin, trifluoroethylene chloride resin, hexafluorochloroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin, and these One or two or more types are preferably selected from the copolymers, but tetrafluoroethylene resin and vinylidene fluoride resin are particularly preferable. The ratio of the lubricant particles in the protective layer is preferably 5 to 70 parts by mass, more preferably 10 to 60% by mass with respect to 100 parts by mass of the acrylic resin. The average particle size of the lubricant particles is preferably 0.01 μm to 1 μm. Particularly preferably, it is 0.05 μm to 0.5 μm. The molecular weight of the resin can be appropriately selected and is not particularly limited.

  As a means for dispersing the filler and lubricant particles, an ultrasonic disperser, a ball mill, a sand grinder, a homomixer and the like can be used, but are not limited thereto.

  In the present invention, an additive such as an antioxidant may be added to the protective layer for the purpose of improving the weather resistance. The same antioxidant as that added to the charge transport layer can be selected.

  In the present invention, in addition to the curable compound, it may be mixed with other resins such as polyester, polycarbonate, polyurethane, acrylic resin, epoxy resin, silicone resin, alkyd resin, and vinyl chloride-vinyl acetate copolymer. It can also be used.

  Solvents for forming the protective layer include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol, benzyl alcohol, toluene, xylene, methylene chloride, methyl ethyl ketone, cyclohexane, acetic acid. Examples thereof include, but are not limited to, ethyl, butyl acetate, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine and diethylamine.

  The protective layer of the present invention is preferably subjected to reaction by irradiation with actinic radiation after natural drying or heat drying after coating.

  As the coating method, a known method such as a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a blade coating method, a beam coating method, and a slide hopper method can be used as in the case of the intermediate layer and the photosensitive layer. .

  The photoreceptor of the present invention is capable of generating a cured resin by irradiating actinic rays on the coating to generate radicals and polymerizing, and curing by forming a cross-linking bond between molecules and within the molecule. preferable. As the active ray, ultraviolet rays and electron beams are particularly preferable.

As the ultraviolet light source, any light source that generates ultraviolet light can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a flash (pulse) xenon, or the like can be used. Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 5 to 500 mJ / cm ² , preferably 5 to 100 mJ / cm ² . The power of the lamp is preferably 0.1 kW to 5 kW, particularly preferably 0.5 kW to 3 kW.

  As an electron beam source, there is no particular limitation on the electron beam irradiation apparatus, and generally, an electron beam accelerator for electron beam irradiation is a curtain beam type that is relatively inexpensive and can provide a large output. Used. The acceleration voltage during electron beam irradiation is preferably 100 to 300 kV. The absorbed dose is preferably 0.5 to 10 Mrad.

  The irradiation time for obtaining the necessary amount of active ray irradiation is preferably from 0.1 second to 10 minutes, and more preferably from 0.1 second to 5 minutes from the viewpoint of curing efficiency or work efficiency of the acrylic compound.

  As the actinic radiation, ultraviolet rays are easy to use and are particularly preferable.

  The photoreceptor of the present invention can be dried before and after irradiating active rays and during irradiation with active rays, and the timing of drying can be appropriately selected by combining them.

  Drying conditions can be appropriately selected depending on the type of solvent, film thickness, and the like. The drying temperature is preferably room temperature to 180 ° C, particularly preferably 80 ° C to 140 ° C. The drying time is preferably 1 minute to 200 minutes, and particularly preferably 5 minutes to 100 minutes.

  The thickness of the protective layer is preferably 0.2 to 10 μm, more preferably 0.5 to 6 μm.

[Conductive support]
The support used in the present invention may be any one as long as it has conductivity, for example, a metal such as aluminum, copper, chromium, nickel, zinc and stainless steel formed into a drum or a sheet, aluminum or copper Metal foils such as those laminated on plastic films, aluminum, indium oxide and tin oxide deposited on plastic films, metals with conductive layers applied alone or with a binder resin, plastic films and For example, paper.

[Middle layer]
In the present invention, an intermediate layer having a barrier function and an adhesive function may be provided between the conductive layer and the photosensitive layer.

  The intermediate layer can be formed by dip coating or the like by dissolving a binder resin such as casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane and gelatin in a known solvent. Of these, an alcohol-soluble polyamide resin is preferred.

  Various conductive fine particles and metal oxides can be contained for the purpose of adjusting the resistance of the intermediate layer. For example, various metal oxides such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide. Ultrafine particles such as indium oxide doped with tin, tin oxide doped with antimony, and zirconium oxide can be used.

  You may use these metal oxides 1 type or in mixture of 2 or more types. When two or more types are mixed, it may take the form of a solid solution or fusion. The average particle diameter of such a metal oxide is preferably 0.3 μm or less, more preferably 0.1 μm or less.

  As the solvent used for the intermediate layer, a solvent in which inorganic particles are well dispersed and the polyamide resin is dissolved is preferable. Specifically, alcohols having 2 to 4 carbon atoms such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol and the like are excellent in solubility and coating performance of the polyamide resin. In addition, examples of co-solvents that can be used in combination with the above-described solvent to obtain favorable effects in order to improve storage stability and particle dispersibility include methanol, benzyl alcohol, toluene, methylene chloride, cyclohexanone, and tetrahydrofuran.

  The density | concentration of binder resin is suitably selected according to the film thickness and production rate of an intermediate | middle layer.

  When the inorganic particles are dispersed, the mixing ratio of the inorganic particles to the binder resin at the time is preferably 20 to 400 parts by mass, more preferably 50 to 200 parts by mass with respect to 100 parts by mass of the binder resin.

  As a means for dispersing the inorganic particles, an ultrasonic disperser, a ball mill, a sand grinder, a homomixer, or the like can be used, but is not limited thereto.

  The method for drying the intermediate layer can be appropriately selected according to the type of solvent and the film thickness, but thermal drying is preferred.

  The thickness of the intermediate layer is preferably from 0.1 to 15 μm, more preferably from 0.3 to 10 μm.

(Charge generation layer)
The charge generation layer used in the present invention preferably contains a charge generation material and a binder resin, and is formed by dispersing and coating the charge generation material in a binder resin solution.

  Examples of the charge generation material include azo raw materials such as Sudan Red and Diane Blue, quinone pigments such as bilenquinone and anthanthrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, and phthalocyanine pigments. It is not something. These charge generating substances can be used alone or in a form dispersed in a known resin.

  As the binder resin of the charge generation layer, a known resin can be used, for example, polystyrene resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, Polyurethane resins, phenol resins, polyester resins, alkyd resins, polycarbonate resins, silicone resins, melamine resins, and copolymer resins containing two or more of these resins (eg, vinyl chloride-vinyl acetate copolymer resins, chlorides) Vinyl-vinyl acetate-maleic anhydride copolymer resin) and poly-vinylcarbazole resin, but are not limited thereto.

  The charge generation layer is formed by dispersing a charge generation material in a solution in which a binder resin is dissolved in a solvent using a disperser to prepare a coating solution, and applying the coating solution to a certain film thickness using a coating device. It is preferable to prepare the film by drying.

  Solvents for dissolving and coating the binder resin used in the charge generation layer include, for example, toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methanol, ethanol, propanol, Examples include butanol, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, and diethylamine, but are not limited thereto.

  As a means for dispersing the charge generating material, an ultrasonic disperser, a ball mill, a sand grinder, a homomixer, or the like can be used, but is not limited thereto.

  The mixing ratio of the charge generating material to the binder resin is preferably 1 to 600 parts by weight, more preferably 50 to 500 parts by weight based on 100 parts by weight of the binder resin. The thickness of the charge generation layer varies depending on the characteristics of the charge generation material, the characteristics of the binder resin, the mixing ratio, and the like, but is preferably 0.01 to 5 μm, more preferably 0.05 to 3 μm. It should be noted that the coating solution for the charge generation layer can prevent the occurrence of image defects by filtering foreign matter and aggregates before coating. The pigment can also be formed by vacuum deposition.

(Charge transport layer)
The charge transport layer used in the photoreceptor of the present invention contains a charge transport material and a binder resin, and is formed by dissolving and coating the charge transport material in a binder resin solution.

  Examples of charge transport materials include carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline compounds Oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, benzidine derivatives, poly-N-vinylcarbazole, poly-1- Two or more kinds of vinylpyrene and poly-9-vinylanthracene may be mixed and used.

  A known resin can be used as the binder resin for the charge transport layer, and polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylic ester resin, and styrene-methacrylic acid. Examples include ester copolymer resins, and polycarbonate is preferred. Further, BPA, BPZ, dimethyl BPA, BPA-dimethyl BPA copolymer and the like are preferable in terms of crack resistance, wear resistance, and charging characteristics.

  The charge transport layer is preferably formed by dissolving the binder resin and the charge transport material to prepare a coating solution, applying the coating solution to a certain film thickness with a coating machine, and drying the coating film.

Examples of the solvent for dissolving the binder resin and the charge transport material include toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, and tetrahydrofuran. 1,4-dioxane, 1,3-dioxolane, pyridine, diethylamine, and the like, but are not limited thereto.
The mixing ratio of the charge transport material to the binder resin is preferably 10 to 500 parts by mass, more preferably 20 to 100 parts by mass with respect to 100 parts by mass of the binder resin.

The thickness of the charge transport layer varies depending on the characteristics of the charge transport material, the characteristics of the binder resin, the mixing ratio, and the like, but is preferably 5 to 40 μm, and more preferably 10 to 30 μm.
An antioxidant, an electronic conductive agent, a stabilizer and the like may be added to the charge transport layer. For the antioxidant, those described in Japanese Patent Application No. 11-200135 and for the electronic conductive agent are described in Japanese Patent Application Laid-Open Nos. 50-137543 and 58-76483.

[Toner Preparation Method]
The method for producing the toner is not particularly limited, but a method using an emulsion association method is preferably used. Particularly preferred is a production method in which resin particles having a multi-stage polymerization structure formed by emulsion polymerization of miniemulsion polymerized particles are associated (aggregated / fused).

Hereinafter, an example of a method for producing a toner by the miniemulsion polymerization association method will be described in detail. In this toner manufacturing method, the toner is manufactured through the following steps.
(1) Dissolution / dispersion step of dissolving or dispersing the release agent in the radical polymerizable monomer (2) The polymerizable monomer solution in which the release agent is dissolved / dispersed is formed into droplets in a solution medium, and the mini Polymerization step for preparing a dispersion of resin particles by emulsion polymerization (3) Colorant dispersion step for dispersing a colorant in the contained solution medium (4) Associating the resin particles with the colorant particles in the solution medium Aggregation / fusion step for obtaining particles (5) Aging step for adjusting the shape by aging the associated particles with heat energy to form toner particles (6) Cooling step for cooling the dispersion of toner particles (7) Cooling The toner particles are solid-liquid separated from the toner particle dispersion, and the surfactant is removed from the toner base. (8) The washed toner particles are dried. (9) The toner particles are dried. Add external additives to toner particles That process steps will be described below.

(1) Dissolution / dispersion step This step is a step of preparing a radical polymerizable monomer solution of the release agent by dissolving or dispersing the release agent in the radical polymerizable monomer.

(2) Polymerization step In a preferred example of this polymerization step, a radical polymerizable monomer solution in which the release agent is dissolved or dispersed is added to a solution medium containing a surfactant, and mechanical energy is increased. In addition, droplets are formed, and then the polymerization reaction proceeds in the droplets by radicals from the water-soluble radical polymerization initiator. Note that resin particles may be added as core particles to the solution medium.

  By this polymerization step, resin particles containing a release agent and a binder resin are obtained. The resin particles to be applied may be colored particles or non-colored particles. The colored resin particles can be obtained by polymerizing a monomer composition containing a colorant. Further, when using uncolored resin particles, by adding a dispersion of colorant particles to the dispersion of resin particles in the aggregation step described later, the resin particles and the colorant particles are aggregated. It can be colored particles.

(3) Dispersing Step of Colorant Particles This step is a step of adding colorant particles to a solution medium containing a surfactant and dispersing the colorant particles in the solution medium using a dispersing device.

  The dispersing device used in the step of dispersing the colorant particles is not particularly limited, and a known device can be used. Preferred dispersing devices include pressure dispersers such as an ultrasonic disperser, a mechanical homogenizer, a manton gourin, and a pressure homogenizer, and medium dispersers such as a sand grinder, a Getzman mill, and a diamond fine mill.

  The colorant may be surface-modified. In the surface modification method of the colorant, the colorant particles are dispersed in a solvent, the surface modifier is added to the dispersion, and the system is reacted by raising the temperature. After completion of the reaction, the colorant particles are filtered off, washed and filtered with the same solvent, and then dried to obtain a colorant treated with the surface modifier.

  From the viewpoint of more preferably obtaining the effects described in the present invention, the average dispersion diameter of the colorant dispersed in the solution medium during the toner production process is preferably 2 to 300 nm, and more preferably 2 to 200 nm. . The average dispersion diameter of the colorant can be controlled by the type and amount of the compound, the amount of the surfactant, the rotational speed of the dispersing device, the dispersion time, and the like.

(4) Aggregation / fusion process The aggregation process is a process of forming colored particles using the resin particles and the colorant particles obtained by the polymerization process. In the aggregation step, resin particles and colorant particles can be aggregated together with release agent particles, internal additive particles such as charge control agents, and the like.

  A preferred aggregating method is to add a salting-out agent composed of an alkali metal salt, an alkaline earth metal salt, or the like as an aggregating agent having a critical aggregation concentration or more in water in which resin particles and colorant particles are present, In this method, the particles are aggregated by heating to a temperature not lower than the glass transition temperature of the resin particles and not lower than the melting peak temperature (° C.) of the release agent.

(5) Aging process Aging is preferably performed by thermal energy (heating).

  Specifically, the liquid containing the associated particles is heated and stirred to adjust the shape of the associated particles to the desired circularity by adjusting the heating temperature, stirring speed, and heating time to obtain toner particles. .

(6) Cooling step This step is a step of cooling (rapid cooling) the dispersion of toner particles. As a cooling treatment condition, cooling is performed at a cooling rate of 1 to 20 ° C./min. The cooling treatment method is not particularly limited, and examples thereof include a method of cooling by introducing a refrigerant from the outside of the reaction vessel, and a method of cooling by directly introducing cold water into the reaction system.

(7) Washing Step In this solid-liquid separation / washing step, the solid-liquid separation process for solid-liquid separation of the toner particles from the dispersion liquid of the toner particles cooled to a predetermined temperature in the above step, and the solid-liquid separated toner A cleaning process is performed to remove deposits such as surfactants and salting-out agents and the alkali agent used in the aging step from the cake (aggregation obtained by agglomerating toner particles in a wet state).

  In the washing treatment, the filtrate is washed with water until the electric conductivity of the filtrate reaches 10 μS / cm. Examples of the filtration method include a centrifugal separation method, a vacuum filtration method using Nutsche and the like, and a filtration method using a filter press and the like, and are not particularly limited.

(8) Drying Step This step is a step of drying the washed toner cake to obtain dried toner particles. Examples of dryers used in this process include spray dryers, vacuum freeze dryers, vacuum dryers, etc., stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers It is preferable to use a stirring dryer or the like. The water content of the dried colored particles is preferably 5% by mass or less, more preferably 2% by mass or less. In addition, when the toner particles subjected to the drying treatment are aggregated due to weak interparticle attraction, the aggregate may be crushed. Here, as the crushing treatment apparatus, a mechanical crushing apparatus such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used.

  The median diameter (D50) based on the volume of the toner is obtained by measuring with the following measuring method.

  Measurement and calculation are performed using a device in which a computer system (manufactured by Coulter) equipped with data processing software “Software V3.51” is connected to Coulter Multisizer 3 (manufactured by Coulter).

  As a measurement procedure, 0.02 g of toner is blended with 20 ml of a surfactant solution (for example, a surfactant solution obtained by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing the toner). After that, ultrasonic dispersion is performed for 1 minute to prepare a toner dispersion. This toner dispersion is injected into a beaker containing ISOTON II (manufactured by Coulter) in a sample stand with a pipette until the display density of the measuring instrument becomes 5% to 10%. By setting this concentration range, a reproducible measurement value can be obtained. In the measuring machine, the measurement particle count is 25000, the aperture diameter is 50 μm, and the frequency value is calculated by dividing the measurement range of 1 to 30 μm into 256 parts. The particle diameter of 50% from the larger volume integrated fraction is defined as the volume-based median diameter.

  Next, materials constituting the toner particles will be described.

(Binder resin)
As the polymerizable monomer constituting the binder resin, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichloro are used. Styrene, p-phenyl styrene, p-ethyl styrene, 2,4-dimethyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn -Styrene or styrene derivatives such as decylstyrene, pn-dodecylstyrene, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-methacrylate Octyl, 2-ethylhexyl methacrylate, stearyl methacrylate Methacrylic acid ester derivatives such as lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, acrylic Acrylates such as isobutyl acid, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, olefins such as ethylene, propylene, isobutylene, vinyl chloride, vinylidene chloride, Halogenated vinyls such as vinyl bromide, vinyl fluoride and vinylidene fluoride, vinyl esters such as vinyl propionate, vinyl acetate and vinyl benzoate, vinyl methyl ether, vinyl ethyl ether Vinyl ethers such as ether, vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone, N-vinyl compounds such as N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone, vinyl naphthalene, vinyl pyridine, etc. Examples include vinyl compounds, acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide. These vinyl monomers can be used alone or in combination.

  Further, it is more preferable to use a combination of monomers having an ionic dissociation group as the polymerizable monomer constituting the resin. For example, it has a substituent such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group as a constituent group of the monomer. Specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumar Acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, acid phosphooxyethyl methacrylate, 3-chloro-2-acid phosphooxy And propyl methacrylate.

  Furthermore, polyfunctionality such as divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, etc. It is also possible to use a crosslinkable resin by using a functional vinyl.

  These polymerizable monomers can be polymerized using a radical polymerization initiator. In this case, an oil-soluble polymerization initiator can be used in the suspension polymerization method. Examples of the oil-soluble polymerization initiator include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carboxyl). Nitriles), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azo- or diazo-based polymerization initiators such as azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate , Cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis- (4,4- t-butylperoxycyclohexyl) propane, tris- Peroxide polymerization initiator or a peroxide such as t- butylperoxy) triazine and the like polymeric initiator having a side chain.

  Moreover, when using an emulsion polymerization method, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, hydrogen peroxide and the like.

(Chain transfer agent)
In order to adjust the molecular weight of the resin, a commonly used chain transfer agent can be used. The chain transfer agent used is not particularly limited. For example, mercaptans such as n-octyl mercaptan, n-decyl mercaptan, tert-dodecyl mercaptan, and mercaptopropionate esters such as n-octyl-3-mercaptopropionate. , Terpinolene, carbon tetrabromide and α-methylstyrene dimer are used.

(Coloring agent)
The colorant used in the present invention is not particularly limited, and commonly used colorants can be used.

  These colorants may be used alone or in combination of two or more as required. The addition amount of the colorant is set in the range of 1 to 30% by mass, preferably 2 to 20% by mass with respect to the whole toner.

(Release agent)
A known compound can be used as the release agent used in the present invention.

  Examples thereof include polyolefin waxes such as polyethylene wax and polypropylene wax, long-chain hydrocarbon waxes such as paraffin wax and sazol wax, dialkyl ketone waxes such as distearyl ketone, carnauba wax, and montan wax. , Trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerol tribehenate, 1,18-octadecanediol distearate, tristearyl trimellitic acid, distearyl maleate And amide waxes such as ethylenediamine behenyl amide and trimellitic acid tristearyl amide.

  The amount of the release agent contained in the toner is preferably 1 to 20% by mass and more preferably 3 to 15% by mass with respect to the whole toner.

(Charge control agent)
A charge control agent can be added to the toner according to the present invention as necessary. A known compound can be used as the charge control agent.

(Developer)
The toner of the present invention can be used as a one-component developer or a two-component developer.

  When used as a one-component developer, a non-magnetic one-component developer, or a magnetic one-component developer containing about 0.1 μm to 0.5 μm of magnetic particles in the toner can be used. be able to.

  Further, it can be mixed with a carrier and used as a two-component developer. As the carrier, conventionally known magnetic particles such as metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead can be used. Ferrite particles are particularly preferable. The particle diameter of the carrier is preferably 20 to 100 μm, more preferably 20 to 70 μm in terms of mass average particle diameter.

  The particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

  The carrier is preferably a carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The coating resin is not particularly limited, and for example, an olefin resin, a styrene resin, a styrene-acrylic resin, a silicone resin, an ester resin, a fluorine-containing polymer resin, or the like is used. The resin for constituting the resin-dispersed carrier is not particularly limited, and known resins can be used. For example, styrene-acrylic resin, polyester resin, fluorine resin, phenol resin, etc. are used. be able to. Among these, a coat carrier coated with a styrene-acrylic resin is more preferable because it can prevent the external additive from being detached and ensure durability.

[Metal oxide (external additive)]
Examples of the material constituting the metal oxide externally added to the toner according to the present invention include silica, alumina, titania, zirconia, magnesium hydroxide, calcium hydroxide, barium titanate, aluminum titanate, strontium titanate, Examples thereof include magnesium titanate, magnesium oxide, cerium oxide, zinc oxide, chromium oxide, cerium oxide, antimony oxide, tungsten oxide, tin oxide, tellurium oxide, and manganese oxide.

  Further, the metal oxide may be subjected to a hydrophobic treatment. In the treatment for hydrophobization, it is preferable to perform a hydrophobizing treatment with a so-called coupling agent such as various titanium coupling agents and silane coupling agents, and further, a hydrophobizing treatment with a higher fatty acid metal salt is also preferably used. . The addition amount of the metal oxide in the toner is preferably 0.10 to 10.0% by mass, and more preferably 0.50 to 5.0% by mass.

  The metal oxide is added as a particle having a number average particle diameter of 3.0 to 300 nm, but it may be used in combination with an 80 to 300 nm particle diameter and a smaller particle diameter external additive. I do not care.

  As a method of measuring the number average particle diameter, there are the following methods.

  Take a 30,000 times photograph with a scanning electron microscope, and capture the photograph image with a scanner. In the image processing analysis device LUZEX AP (manufactured by Nireco), the external additive present on the toner surface of the photographic image is binarized, and the horizontal ferret diameter for 100 inorganic fine particles is calculated. The value is the number average particle diameter. When the inorganic fine particles are present on the toner surface as some aggregates, the particle diameter of the primary particles forming the aggregates is measured.

[Metal soap]
In addition to the inorganic external additive, a metal soap (lubricant) is added to the toner of the present invention. For example, zinc stearate, aluminum, copper, magnesium, calcium salt, zinc oleate, manganese, iron, copper, magnesium salt, zinc palmitate, copper, magnesium, calcium salt, linoleic acid Examples thereof include metal salts of higher fatty acids such as zinc and calcium salts, and zinc and calcium ricinoleic acid salts. The addition amount of these metal soaps is preferably about 0.01 to 5% by mass with respect to the toner.

  The metal soap may be added to the toner particles like the above-described release agent, and the present invention does not delete it.

[Addition of metal oxide and metal soap]
As a method for externally adding the metal oxide / metal soap to the toner, various known mixing devices such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer can be used.

[Intermediate transfer member]
The intermediate transfer member secondarily transfers the toner on the intermediate transfer member that has been primarily transferred from the photosensitive member to the transfer material, and then removes the transfer residual toner that has not been transferred onto the intermediate transfer member. It is cleaned with a blade or a fur brush. If the surface of the intermediate transfer member does not damage the surface of the intermediate transfer member by the cleaning member and the transfer residual toner is well cleaned, even if a large number of sheets are printed, the print image does not get dirty due to poor cleaning, and high quality toner Images can be obtained continuously.

  Further, the intermediate transfer member can be provided with a low surface energy layer on the surface thereof, thereby further improving the secondary transfer efficiency and suppressing foreign matter adhesion.

The intermediate transfer member of the present invention preferably has the following characteristics.
1. 1. Structure in which an elastic layer is provided on the outer periphery of a resin substrate and a surface layer is provided thereon. The layer thickness of the surface layer is 10 to 500 nm, preferably 30 to 300 nm
3. The Young's modulus measured by the nanoindentation method on the surface of the intermediate transfer member is 0.1 to 5.0 GPa, preferably 0.1 to 1.0 GPa
4). The Young's modulus measured by the nanoindentation method on the surface of the intermediate transfer member is 0.0 to 2.0 GPa, preferably 0.0 to 1.0 GPa larger than the Young's modulus measured by the nanoindentation method of the elastic layer.

  With the above characteristics, even when a large number of sheets are printed, high transfer characteristics can be ensured, character images are not missing, and the cleaning member is not damaged, and a high-quality toner image can be obtained.

  The intermediate transfer member of the present invention preferably has an elastic layer provided on the outer periphery of a resin substrate and a surface layer provided thereon. The surface layer is composed of one or more hard layers, or one or more hard layers and a low surface energy layer.

(Resin substrate)
The resin substrate has rigidity that prevents the intermediate transfer member from being deformed by a load applied to the intermediate transfer member from a cleaning blade as a cleaning member, and reduces the influence on the transfer portion. The resin substrate is preferably formed using a material having a Young's modulus measured by the nanoindentation method in the range of 5.0 to 15.0 GPa, and more preferably in the range of 8.0 to 15.0 GPa. .

  Examples of the material that exhibits such performance include resin materials such as polycarbonate, polyphenylene sulfide, polyvinylidene fluoride, polyimide, polyether, and ether ketone. Among these, polyimide, polycarbonate, and polyphenylene sulfide are preferable. The Young's modulus of these resin materials measured by the nanoindentation method exceeds 5.0 GPa, and has a thickness of 50 to 200 μm and satisfies the mechanical properties as a resin substrate.

The resin substrate according to the present invention is preferably a seamless belt or drum prepared by adding a conductive substance to a resin material and adjusting an electric resistance value (volume resistivity) to 10 ⁵ to 10 ¹¹ Ω · cm.

  Carbon black can be used as the conductive substance added to the resin material. As carbon black, neutral or acidic carbon black can be used. The amount of the conductive material used varies depending on the type of the conductive material to be used, but it may be added so that the volume resistance value and the surface resistance value of the intermediate transfer member are within a predetermined range. Usually, 100 parts by mass of the resin material It is 10-20 mass parts with respect to this, Preferably it is 10-16 mass parts.

(Elastic layer)
The elastic layer according to the present invention can be formed from at least one of chloroprene rubber, nitrile rubber, styrene-butadiene rubber, silicone rubber, and urethane rubber.

  The elastic layer may be a layer formed using a material obtained by blending the above-described resin material and elastic material. Examples of the elastic material include polyurethane, chlorinated polyisoprene, nitrile rubber, chloroprene rubber, ethylene-propylene-diene rubber, hydrogenated polybutadiene, butyl rubber, and silicone rubber. These may be used alone or in combination of two or more.

  The Young's modulus measured by the nanoindentation method of the elastic layer is preferably 0.1 to 2.0 GPa, more preferably 0.1 to 1.0 GPa.

  The thickness of the elastic layer is preferably 100 to 500 μm.

The elastic layer according to the present invention is preferably a layer prepared by dispersing a conductive substance in an elastic material and adjusting an electric resistance value (volume resistivity) to 10 ⁵ to 10 ¹¹ Ω · cm.

  Carbon black, zinc oxide, tin oxide, silicon carbide, etc. can be used as the conductive substance added to the elastic layer. As carbon black, neutral or acidic carbon black can be used. The amount of the conductive material used varies depending on the type of the conductive material to be used, but may be added so that the volume resistance value and the surface resistance value of the elastic layer are within a predetermined range. It is 10-20 mass parts with respect to it, Preferably it is 10-16 mass parts.

(Surface layer)
The surface layer is composed of a hard layer or a hard layer and a low surface energy layer.

  The Young's modulus measured by the nanoindentation method on the surface of the intermediate transfer member on which the surface layer is laminated is 0.1 to 5.0 GPa, preferably 0.1 to 2.0 GPa, more preferably 0.1 to 1.0 GPa. is there.

(Hard layer)
The hard layer according to the present invention is preferably a metal oxide film, a silicon film, or a carbon film. Specific examples include metal oxide films such as silicon oxide, silicon oxynitride, silicon nitride, titanium oxide, titanium oxynitride, titanium nitride, and aluminum oxide. Among these, a silicon oxide film is preferable. Moreover, the inorganic compound which consists of those mixtures is also preferable.

  The hard layer in this invention should just be 1 layer or more. The layer of the hard layer may have a structure in which the hardness gradually increases or the density gradually increases from directly above the elastic layer toward the surface of the hard layer farthest from the elastic layer.

  The thickness of the hard layer is 10 to 500 nm, preferably 20 to 400 nm, more preferably 30 to 300 nm.

  The film thickness is a value obtained by measurement using “MXP21 (manufactured by Mac Science)”. A specific measurement of the film thickness can be performed by the following method.

  Copper is used as the target of the X-ray source and it is operated at 42 kV and 500 mA. A multilayer parabolic mirror is used for the incident monochromator. The incident slit is 0.05 mm × 5 mm, and the light receiving slit is 0.03 mm × 20 mm. Measurement is performed by the FT method with a step width of 0.005 ° and a step of 10 seconds from 0 to 5 ° in the 2θ / θ scan method. With respect to the obtained reflectance curve, Reflectivity Analysis Program Ver. 1 is used to perform curve fitting, and each parameter is obtained so that the residual sum of squares of the actually measured value and the fitting curve is minimized. The film thickness of the laminated film is obtained from each parameter.

  If the thickness of the hard layer is less than 10 nm, durability and surface strength will be insufficient, and scratches will occur due to transfer to cardboard, etc., and the thin film will eventually be worn unevenly, resulting in decreased transfer rate and uneven transfer. Is likely to occur. If it exceeds 1000 nm, adhesion and bending resistance are insufficient, so that when a large number of sheets are used, cracking and peeling are likely to occur, and the time required for film formation increases, which is not preferable from the viewpoint of production.

(Low surface energy layer)
The low surface energy layer according to the present invention is a layer containing fluorine or silicon. The film thickness of the low surface energy layer is preferably 1 to 10 nm. Although the formation method of a surface energy layer is not specifically limited, It can form by apply | coating the coating liquid containing a fluorine or a silicon on a hard layer.

  Next, an image forming method and an image forming apparatus using the intermediate transfer member of the present invention will be described.

[Image Forming Method, Image Forming Apparatus]
The intermediate transfer member of the present invention is suitably used for image forming apparatuses such as electrophotographic copying machines, printers, facsimiles and the like. In the image forming method, a toner image carried on the surface of a photoreceptor is primarily transferred to the surface, the transferred toner image is held, and the held toner image is transferred onto the surface of a transfer material such as recording paper. What is necessary is just to perform secondary transfer using. The intermediate transfer member may be belt-shaped or drum-shaped.

  The image forming apparatus having the intermediate transfer member of the present invention will be described by taking a tandem type full-color copying machine as an example.

  FIG. 1 is a cross-sectional configuration diagram illustrating an example of a color image forming apparatus.

  This color image forming apparatus 1 is called a tandem type full-color copying machine, and includes an automatic document feeder 13, a document image reading device 14, a plurality of exposure means 13Y, 13M, 13C, and 13K, and a plurality of sets of images. The forming unit 10 </ b> Y, 10 </ b> M, 10 </ b> C, 10 </ b> K, an intermediate transfer body unit 17, a paper feeding unit 15, and a fixing unit 124.

  An automatic document feeder 13 and a document image reading device 14 are arranged on the upper part of the main body 12 of the image forming apparatus, and an image of the document d conveyed by the automatic document feeder 13 is an optical system of the document image reading device 14. The image is reflected and imaged by the line image sensor CCD.

  The analog signal obtained by photoelectrically converting the original image read by the line image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing, and the like in an image processing unit (not shown), and then exposure means 13Y, A drum-shaped photoconductor (hereinafter also referred to as a photoconductor) 11Y as a first image carrier that is sent to 13M, 13C, and 13K as digital image data for each color and corresponding to the exposure means 13Y, 13M, 13C, and 13K. A latent image of image data of each color is formed on 11M, 11C, and 11K.

  The image forming units 10Y, 10M, 10C, and 10K are arranged in tandem in the vertical direction, and can be rotated by winding rollers 171, 172, 173, and 174 around the left side of the photoreceptors 11Y, 11M, 11C, and 11K in the drawing. An intermediate transfer member (hereinafter, referred to as an intermediate transfer belt) 170 of the present invention, which is a semiconductive and seamless belt-like second image bearing member stretched on the belt, is disposed.

  The intermediate transfer belt 170 of the present invention is driven in the direction of the arrow through a roller 171 that is rotationally driven by a driving device (not shown).

  The image forming unit 10Y that forms a yellow image includes a charging unit 12Y, an exposure unit 13Y, a developing unit 14Y, a primary transfer roller 15Y as a primary transfer unit, and a cleaning unit 16Y disposed around the photoreceptor 11Y. Have.

  The image forming unit 10M that forms a magenta image includes a photoreceptor 11M, a charging unit 12M, an exposure unit 13M, a developing unit 14M, a primary transfer roller 15M as a primary transfer unit, and a cleaning unit 16M.

  The image forming unit 10C that forms a cyan image includes a photoreceptor 11C, a charging unit 12C, an exposure unit 13C, a developing unit 14C, a primary transfer roller 15C as a primary transfer unit, and a cleaning unit 16C.

  The image forming unit 10K that forms a black image includes a photoreceptor 11K, a charging unit 12K, an exposure unit 13K, a developing unit 14K, a primary transfer roller 15K as a primary transfer unit, and a cleaning unit 16K.

  The toner replenishing means 141Y, 141M, 141C, and 141K replenish new toner to the developing devices 14Y, 14M, 14C, and 14K, respectively.

  Here, the primary transfer rollers 15Y, 15M, 15C, and 15K are selectively operated according to the type of image by a control unit (not shown), and the intermediate transfer belt 170 is respectively applied to the corresponding photoreceptors 11Y, 11M, 11C, and 11K. To transfer the image on the photoreceptor.

  In this way, the images of the respective colors formed on the photoreceptors 11Y, 11M, 11C, and 11K by the image forming units 10Y, 10M, 10C, and 10K are rotated by the primary transfer rollers 15Y, 15M, 15C, and 15K. The image is sequentially transferred onto the intermediate transfer belt 170, and a combined color image is formed.

  That is, the intermediate transfer belt primarily transfers the toner image carried on the surface of the photosensitive member to the surface, and holds the transferred toner image.

  Further, the transfer material P as a recording medium accommodated in the paper feeding cassette 151 is fed by the paper feeding means 15 and then passed through a plurality of intermediate rollers 122A, 122B, 122C, 122D, and a registration roller 123, and the secondary material P. The toner image is conveyed to a secondary transfer roller 117 serving as a transfer unit, and the combined toner image on the intermediate transfer member is collectively transferred onto the transfer material P by the secondary transfer roller 117.

  That is, the toner image held on the intermediate transfer member is secondarily transferred to the surface of the transfer object.

  Here, the secondary transfer unit 6 presses the transfer material P against the intermediate transfer belt 170 only when the transfer material P passes through the secondary transfer unit 6 and performs the secondary transfer.

  The transfer material P onto which the color image has been transferred is fixed by the fixing device 124, sandwiched by the paper discharge roller 125, and placed on the paper discharge tray 126 outside the apparatus.

  On the other hand, after the color image is transferred to the transfer material P by the secondary transfer roller 117, the residual toner is removed by the cleaning unit 8 from the intermediate transfer belt 170 from which the transfer material P is separated by curvature.

  Here, the intermediate transfer member may be replaced with a rotating drum-like member as described above.

  Next, the configuration of the primary transfer rollers 15Y, 15M, 15C, and 15K as the primary transfer means in contact with the intermediate transfer belt 170 and the secondary transfer roller 117 will be described.

The primary transfer rollers 15Y, 15M, 15C, and 15K disperse a conductive material such as carbon in a rubber material such as polyurethane, EPDM, or silicone on a peripheral surface of a conductive core metal such as stainless steel having an outer diameter of 8 mm. Or a solid state or foamed sponge state with a volume resistance of about 10 ⁵ to 10 ⁹ Ω · cm, a thickness of 5 mm, and a rubber hardness of about 20 to 70 ° (asker It is formed by coating a semiconductive elastic rubber having a hardness C).

For example, the secondary transfer roller 117 disperses a conductive material such as carbon in a rubber material such as polyurethane, EPDM, or silicone on a peripheral surface of a conductive metal core such as stainless steel having an outer diameter of 8 mm, or an ionic conductive material. Semi-conducting material containing a material and having a volume resistance of about 10 ⁵ to 10 ⁹ Ω · cm in a solid state or foamed sponge state with a thickness of 5 mm and a rubber hardness of about 20 to 70 ° (Asker hardness C) It is formed by covering an elastic rubber.

[Transfer material]
The transfer material used in the present invention is a support for holding a toner image, and is usually called an image support, a transfer material, or transfer paper. Specific examples include various kinds of transfer materials such as plain paper from thin paper to thick paper, coated printing paper such as art paper and coated paper, commercially available Japanese paper and postcard paper, plastic films for OHP, and cloth. However, it is not limited to these.

  Next, representative embodiments of the present invention will be shown, and the configuration and effects of the present invention will be further described.

  Unless otherwise specified, “part” in the sentence represents mass part and “%” represents mass%.

[Preparation of colored particles]
(Preparation of core resin particles)
<< Preparation of core resin particle 1 >>
(1) First-stage polymerization In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device, 110.9 parts by mass of styrene, 52.8 parts by mass of n-butyl acrylate, 12.3 parts by mass of methacrylic acid 93.8 parts by mass of paraffin wax “HNP-57” (manufactured by Nippon Seiki Co., Ltd.) was added as a mold release agent to the mixed solution, and heated to 80 ° C. to dissolve.

  On the other hand, a surfactant solution was prepared by dissolving 2.9 parts by mass of sodium polyoxyethylene (2) dodecyl ether sulfate in 1340 parts by mass of ion-exchanged water.

  After heating this surfactant solution to 80 ° C., the polymerizable monomer solution was mixed and dispersed for 2 hours with a mechanical dispersion “CLEARMIX” (manufactured by M Technique Co., Ltd.) having a circulation path, and dispersed particles (245 nm An emulsified liquid containing emulsified particles having) was prepared.

  Next, after adding 1460 parts by mass of ion-exchanged water, an initiator solution in which 6 parts by mass of a polymerization initiator (potassium persulfate) is dissolved in 142 parts by mass of ion-exchanged water, 1.8 parts by mass of n-octyl mercaptan, Then, the temperature was set to 80 ° C., and the system was heated and stirred at 80 ° C. for 3 hours to perform polymerization (first stage polymerization) to prepare resin particles. This is designated as “resin particle C1”.

(2) Second stage polymerization (formation of outer layer)
An initiator solution in which 5.1 parts by mass of potassium persulfate is dissolved in 197 parts by mass of ion-exchanged water is added to the “resin particles C1” obtained as described above, and styrene 282 is subjected to a temperature condition of 80 ° C. A monomer mixed solution composed of 2 parts by mass, 134.4 parts by mass of n-butyl acrylate, 31.4 parts by mass of methacrylic acid, and 4.93 parts by mass of n-octyl mercaptan was added dropwise over 1 hour. After completion of the dropwise addition, the second-stage polymerization (formation of the outer layer) was performed by heating and stirring for 2 hours, and then cooled to 28 ° C. to obtain “core resin particles 1”.

  The core resin particles 1 had a weight average molecular weight of 21,300. The mass average particle diameter of the composite resin particles constituting “core resin particle 1” was 180 nm. The Tg of the resin particles was 39 ° C.

(Preparation of resin particles for shell)
A surfactant solution in which 2.0 parts by mass of polyoxyethylene (2) sodium dodecyl ether sulfate was dissolved in 3000 parts by mass of ion-exchanged water was charged into a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction device. The internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream.

  An initiator solution in which 10 parts by mass of a polymerization initiator (potassium persulfate: KPS) is dissolved in 200 parts by mass of ion-exchanged water is added to this surfactant solution, and 528 parts by mass of styrene and 176 of n-butyl acrylate are added. Polymerization is carried out by adding dropwise a monomer mixture comprising 3 parts by mass, 120 parts by mass of methacrylic acid and 22 parts by mass of n-octyl mercaptan over 3 hours, and heating and stirring the system at 80 ° C. for 1 hour. To prepare resin particles. This is referred to as “shell resin particles”.

  The weight average molecular weight of the resin particles for shell was 12,000, the mass average particle diameter was 120 nm, and Tg was 53 ° C.

(Preparation of colorant dispersion)
A dispersion of colorant particles was prepared using 420 parts by mass of the colorant “Regal 330R” (manufactured by Cabot). This is designated as “colorant dispersion C1”. The average dispersion diameter of the colorant particles in the colorant dispersion was measured using a dynamic light scattering particle size analyzer “Microtrack UPA150” (manufactured by Nikkiso Co., Ltd.), and found to be 150 nm.

[Preparation of colored particles]
(Preparation of colored particles 1)
<Formation of core>
420.7 parts by mass (solid content conversion) of “core resin particles 1”, 900 parts by mass of ion-exchanged water, and 200 parts by mass of “colorant particle dispersion C1”, a temperature sensor, a cooling pipe, a nitrogen introducing device, The mixture was stirred in a reaction vessel equipped with a stirrer. After adjusting the temperature in the container to 30 ° C., 5 mol / L sodium hydroxide aqueous solution was added to this solution to adjust the pH to 9.

  Next, an aqueous solution obtained by dissolving 2 parts by mass of magnesium chloride hexahydrate in 1000 parts by mass of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After standing for 3 minutes, the temperature was raised and the system was heated to 65 ° C. over 60 minutes. In this state, the particle size of the associated particles was measured with “Coulter Multisizer 3” (manufactured by Coulter), and when the median system (D50) on the volume basis of the particles became 5.5 μm, sodium chloride 40.2 An aqueous solution in which 1000 parts by mass of ion-exchanged water is dissolved is added to stop the growth of particle size, and further, the fusion is continued by heating and stirring at a liquid temperature of 70 ° C. for 1 hour as an aging treatment. Part 1 "was formed.

  The circularity of the “core part 1” was measured by “FPIA2100” (manufactured by Systex) and found to be 0.930.

<< Formation of shell layer (shelling operation) >>
Next, at 65 ° C., 50 parts by mass (in terms of solid content) of “resin particles for shell” is added, and an aqueous solution in which 2 parts by mass of magnesium chloride hexahydrate is dissolved in 1000 parts by mass of ion-exchanged water is added over 10 minutes. Then, the temperature is raised to 70 ° C. (shelling temperature), stirring is continued for 1 hour, and the particles of “resin particles for shell” are fused to the surface of “core part 1”, and then 75 ° C. And a aging treatment was performed for 20 minutes to form a shell layer.

  Here, 40.2 parts by mass of sodium chloride was added and cooled to 30 ° C. under the condition of 8 ° C./min to obtain “an aqueous solution containing toner base particles”.

《Cleaning and drying process》
The aqueous solution containing the toner base particles was subjected to solid-liquid separation with a basket-type centrifuge “MARK III model number 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.) to form a wet cake of toner base particles. The wet cake was washed with water using the basket-type centrifuge until the electric conductivity of the filtrate reached 5 μS / cm, and then transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). It dried until it became%, and the "colored particle 1" was produced. The colored particle 1 was a particle having a core-shell structure with a median diameter (D50) of 6.5 μm and a Tg of 39.5 ° C. on a volume basis.
(Development of developer)
Toner bases 1 to 7 were prepared by adding metal oxides and metal soaps shown in Table 1 to the toner base prepared by the polymerization method and stirring with a Henschel mixer. The addition amount of the metal oxide and the metal soap represents mass% with respect to the toner base.

Large diameter silica: NAX50 (Nippon Aerosil Co., Ltd.)
Small diameter silica: R805 (Nippon Aerosil Co., Ltd.)
Titania: STT30S (Titanium Industry Co., Ltd.)
[Production of photoconductor]
(Preparation of titanium oxide particles)
0.2 part of methyl hydrogen polysiloxane is dissolved and dispersed in 10 parts of ethanol / n-propyl alcohol / THF (45:20:35 volume ratio), and rutile-type titanium oxide particles (number average primary particles) in the mixed solvent. 35 nm in diameter: 5% primary surface treatment with alumina) is added, and after stirring for 1 hour, the surface treatment (secondary treatment) is performed to separate from the solvent, followed by drying by heating and surface treatment. Of titanium oxide particles 1 were obtained. The titanium oxide particles are used for the intermediate layer and the protective layer.
(Preparation of photoreceptor 1)
Photoreceptor 1 was produced as follows.

  First, a cylindrical aluminum substrate having a diameter of 30 (processed to a ten-point average surface roughness Rz = 0.81 μm as defined in JIS B0601 by cutting) was prepared.

<Formation of intermediate layer>
Binder resin (Compound N-1 below) 1 part Ethanol / n-propyl alcohol / THF (45:20:35 volume ratio) After mixing 20 parts with stirring and dissolution,
4.2 parts of titanium oxide particles 1 were mixed, and the mixed solution was dispersed by a bead mill to prepare an intermediate layer coating solution. After filtering this coating solution, it was applied onto the cylindrical aluminum substrate by a dip coating method to form an intermediate layer having a dry film thickness of about 2 μm.

<Formation of charge generation layer>
Titanyl phthalocyanine pigment (a titanyl phthalocyanine pigment having a maximum diffraction peak at a Bragg angle of 2θ = 27.3 ° as measured by Cu-Kα characteristic X-ray diffraction spectrum) 20 parts Polyvinyl butyral (BX-1, Sekisui Chemical Co., Ltd.) 10 parts Methyl ethyl ketone 700 parts Cyclohexanone 300 parts were mixed and dispersed for 10 hours using a sand mill to prepare a charge generation layer coating solution. This coating solution was applied onto the intermediate layer by a dip coating method to form a charge generation layer having a dry film thickness of 0.3 μm.

<Formation of charge transport layer>
The following components were mixed and dissolved to prepare a charge transport layer coating solution. This coating solution was applied onto the charge generation layer by a dip coating method and dried at 120 ° C. for 70 minutes to form a charge transport layer having a dry film thickness of 20 μm.

Charge transport material (compound B below) 50 parts Polycarbonate resin “Iupilon-Z300” (manufactured by Mitsubishi Gas Chemical) 100 parts Antioxidant 2,6-ditertiarybutyl 4-methylphenol 8 parts Tetrahydrofuran / toluene (volume ratio 8 / 2) 750 parts

<Formation of protective layer>
1.0 part of the following curable material (1)
1-propanol 5.1 parts Methyl isobutyl ketone Dissolved in 2.4 parts of mixed solvent. further,
Fluorine resin fine particles (average particle size 300 nm) 0.6 part Titanium oxide particles 1 0.6 part is added and dispersed with an ultrasonic homogenizer for 15 minutes to obtain a dispersion containing a curable material, fluororesin fine particles, and titanium oxide particles. Obtained. 0.05 part of a radical curing initiator (Compound D) was added to the dispersion to prepare a protective layer coating solution.

Curable material (1): Mixture of the following (A) and (B) in a mass ratio of 3/7 (A) Exemplary compound (30) Ditrimethylolpropane tetraacrylate (molecular weight 466.5, tetrafunctional, trade name Aronix M- 408, manufactured by Toa Gosei Chemical Industry Co., Ltd.)
(B) Exemplary compound (39) (molecular weight 450, bifunctional, trade name Ebecryl E-4858, manufactured by Daicel Cytec Co., Ltd.)

  The protective layer coating solution was dip-coated on the photosensitive layer. After coating and drying at room temperature for 10 minutes, the photosensitive drum was positioned 100 mm away from a 2 kW high-pressure mercury lamp and rotated for 3 minutes while rotating and the protective layer was reacted to cure. After photocuring, heat drying was performed at 120 ° C. for 30 minutes to prepare an electrophotographic photosensitive member provided with a 2 μm protective layer.

(Photoconductor 2 production)
Photoreceptor 2 was produced in the same manner as Photoreceptor 1 except that the curable material was changed to (2) below and titanium oxide particles 1 was changed to 0.8 part.

Curable material (2):
Exemplified compound (7) Dipentaerythritol hexaacrylate (molecular weight 547, hexafunctional, trade name KAYARAD DPHA, manufactured by Nippon Kayaku Co., Ltd.)
(Preparation of photoreceptor 3)
A photoconductor 3 was produced in the same manner as the photoconductor 1 except that the titanium oxide particles 1 were 0.4 parts.

(Preparation of photoconductor 4)
Photoreceptor 4 was produced in the same manner as Photoreceptor 1 except that the curable material was changed to (3) below.

Curable material (3):
Illustrative compound (31) pentaerythritol tetraacrylate (molecular weight 352.3, tetrafunctional, trade name Aronix M-450, manufactured by Toagosei Co., Ltd.)
(Preparation of photoconductor 5)
Photoconductor 5 was prepared in the same manner as photoconductor 1 except that 0.8 parts of titanium oxide particles 1 were used.

(Preparation of photoreceptor 6)
Photoreceptor 6 was produced in the same manner as in Photoreceptor 1 except that the curable material was changed to (4) below.

Curable material (4):
Urethane triacrylate (molecular weight 1500, trifunctional, trade name Ebecryl 9260, manufactured by Daicel Cytec)
(Preparation of photoconductor 7)
Photoreceptor 7 was produced in the same manner as in Photoreceptor 1 except that the curable material was changed to (5) below.

Curable material (5):
Urethane diacrylate (molecular weight 5000, bifunctional, trade name Ebecryl 230, manufactured by Daicel Cytec Co., Ltd.)
(Preparation of comparative photoreceptor 1)
In the production of the photoreceptor 1, a laminated photoreceptor including an intermediate layer, a charge generation layer, and a charge transport layer was similarly formed until the charge transport layer was formed.

  Next, the following components were mixed and dissolved to prepare a protective layer coating solution. This coating solution was applied onto the charge transport layer by a circular slide hopper method and dried at 120 ° C. for 70 minutes to form a protective layer having a dry film thickness of 5 μm.

Charge transport material (compound B) 20 parts Polycarbonate resin “Iupilon-Z300” (manufactured by Mitsubishi Gas Chemical) 30 parts Antioxidant 2,6-ditertiarybutyl 4-methylphenol 8 parts Titanium oxide particles 1 6 parts Tetrahydrofuran / toluene (Volume ratio: 8/2) 750 parts This photoconductor was used as comparative photoconductor 1.

(Preparation of comparative photoreceptor 2)
A photoconductor was prepared in the same manner as the photoconductor 1 except that the titanium oxide particles 1 were not added. This photoconductor was used as a comparative photoconductor 2.

(Prepared on comparative photoreceptor 3)
A photoconductor was prepared in the same manner except that zinc antimonate (CX-Z210IP particle size: 15 nm) was used in place of the titanium oxide particles 1 in the production of the photoconductor 1, and this photoconductor was used as a comparative photoconductor 3.

(Preparation of comparative photoconductor 4)
A photoconductor was prepared in the same manner as the photoconductor 1 except that alumina particles (AKP-50, manufactured by Sumitomo Chemical Co., Ltd.) were used in place of the titanium oxide particles 1. did.

(Preparation of comparative photoreceptor 5)
A photoconductor was prepared in the same manner as the photoconductor 1 except that antimony-doped tin oxide fine particles (T-1, manufactured by Mitsubishi Materials Corporation) were used instead of the titanium oxide particles 1, and this photoconductor was used as a comparative photoconductor. It was set to 5.

  Table 2 shows the structure of the photoreceptor sample. In addition, the addition amount of a metal oxide particle represents the mass% with respect to a polycarbonate resin about the comparative photoconductor 1, and represents the mass% with respect to a curable compound otherwise.

[Performance evaluation]
Under normal temperature and humidity conditions (20 ° C., 50% RH), toner of bizhub C-351 manufactured by Konica Minolta Business Technologies, toners 1 to 8, toners 1 to 7, and photosensitive members 1 to 5 for producing photosensitive members Were changed as shown in Table 3, and the following items were evaluated after 5000 continuous shootings.

  The evaluation items were “middle defect”, “comet-like defect”, and “photoreceptor scratch”, and all were performed according to the following criteria.

◎: Not recognized at all ○: Recognized, but no problem in practical use △: Recognized, but practically possible ×: Problem in practical use

  As is apparent from the results shown in Table 3, the examples in the present invention are good in all the characteristics, but the comparative examples outside the present invention have problems in at least any of the characteristics.

1 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus in which an intermediate transfer member of the present invention can be used.

Explanation of symbols

1 Color Image Forming Apparatus 10Y, 10M, 10C, 10K Image Forming Unit 11Y, 11M, 11C, 11K Drum-shaped photoconductor (also referred to as photoconductor)
13Y, 13M, 13C, 13K Exposure means 17 Intermediate transfer member unit 170 Intermediate transfer member (intermediate transfer belt)

Claims (4)

An image forming method comprising a step of transferring a toner developed on a photosensitive member in which at least a photosensitive layer and a protective layer are laminated in this order on a conductive support to an intermediate transfer member, wherein the toner comprises at least a metal oxide and a metal soap And a protective layer containing at least a component obtained by reacting a photocurable acrylic compound having at least an acryloyl group or a methacryloyl group , and titanium oxide particles. Image forming method. 2. The image forming method according to claim 1, wherein the number of acryloyl groups or methacryloyl groups of the photocurable acrylic compound is 3 or more. 3. The image forming method according to claim 1, wherein the photocurable acrylic compound has a curable reactive group equivalent of 1000 or less.   An image forming apparatus that forms an image by the image forming method according to claim 1.

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