JPH11125920A - Composition for electric charge transporting layer and electrophotographic photoreceptor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrophotographic photoreceptor which enhances the image quality of a printed image, ensures improved printing resistance and a prolonged service life and is excellent in quick optical responsiveness without requiring a halogen-contg. solvent from the standpoint of the protection of environment. SOLUTION: The compsn. for an electric charge transporting layer contains fine particles of a crosslinked polymer having 30-1,000 nm average diameter obtd. by polymerizing a blend of 50-99.95 wt.% monoethylenically unsatd. monomer and 0.05-50 wt.% crosslinking agent having >=2 ethylenically unsatd. bonds and an acrylic resin. The electrophotographic photoreceptor has an electric charge transporting layer formed by using the compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for a charge-transporting layer of a function-separated type organic electrophotographic photoreceptor, which is used by being mounted on an electrophotographic apparatus (printer, copier, etc.) by the Carlson method, and this composition. The present invention relates to an electrophotographic photosensitive member using a material.

[0002]

2. Description of the Related Art Electrophotographic photoreceptors using an organic photoconductive compound have been extensively studied recently because they are advantageous in terms of flexibility, lightness, surface smoothness, and price. Among them, a function-separated electrophotographic photoreceptor provided with a charge generation layer that generates charge carriers by light absorption and a charge transport layer that transports the generated charge carriers by an electric field has been conventionally used.
Recently, rapid progress has been made because photoresponsiveness and sensitivity, which were major drawbacks of electrophotographic photoreceptors using an organic photoconductive compound, can be greatly improved.

A function-separated type organic electrophotographic photoreceptor comprises a charge generation layer mainly composed of a photoconductive substance on a conductive substrate, and a charge transport layer composed of a charge transportable substance and a binder resin. I have. Since the charge transport layer is the outermost layer as a photoreceptor, it must be chemically stable and must withstand mechanical abrasion due to the development and cleaning processes.

Hitherto, as a binder resin for a charge transport layer of an electrophotographic photosensitive member, bisphenol A type polycarbonate resin represented by the following structural formula 1 has been most commonly used in terms of transparency and mechanical strength. I have.

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Since the bisphenol A type polycarbonate resin has poor solubility as can be seen from the above structure, methylene chloride, 1,2-dichloromethane,
In fact, a halogen-based solvent such as 1,1,2-trichloromethane alone or a mixture thereof, or a mixed solvent of a halogen-based solvent and a non-halogen-based solvent is used.

In order to obtain high-speed photoresponsiveness, it is necessary to increase the amount of the charge transporting substance in the composition for the charge transporting layer.
General.

However, recently, the electrophotographic photoreceptor has been required to obtain a high quality printed image obtained by an electrophotographic apparatus such as a copying machine and a laser beam printer and to increase the printing speed by downsizing the electrophotographic apparatus. There is an increasing demand for higher image quality, longer printing life, and faster light response of printed images.

In the composition for a charge transporting layer in which the amount of the charge transporting substance is increased, the charge transporting substance and the bisphenol A type polycarbonate resin are uniformly dissolved in a solution state, but this is dried to remove the solvent. In the thus formed charge transport layer in the solid state, the charge transporting substance and the bisphenol A-type polycarbonate resin undergo phase separation, and the coating film tends to be uneven in both morphology and composition. When an electrophotographic photoreceptor is formed using the composition for a charge transport layer, fog, black spots, image defects such as white spots occur from the beginning of use,
It is not possible to obtain an electrophotographic photoreceptor that satisfies high-speed light responsiveness and high image quality.Because of poor abrasion resistance, repeated use reduces the thickness of the photoreceptor and causes image defects such as fog and black spots. During repeated use, the developer (toner) adheres, causing a so-called filming phenomenon, which may cause a problem such as a streak-like defect in an image, and the printing life is not sufficient. . On the other hand, the movement to protect the global environment has been intensified, and the elimination of CFCs that destroy the ozone layer and the regulation of halogenated solvents that pollute groundwater have been increasing.

[0009]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, eliminates the need for a halogen-based solvent from the standpoint of environmental protection, improves the quality of a printed image, increases the printing life, and improves the printing life. An object of the present invention is to provide an electrophotographic photoreceptor excellent in fast light response.

[0010]

According to the present invention, the above object has been attained by using an acrylic resin containing specific crosslinked polymerized fine particles in a composition for a charge transport layer.
That is, the present invention relates to a monoethylenically unsaturated monomer 50 to 50.
It contains crosslinked polymer fine particles having an average diameter of 30 to 1000 nm obtained by blending 99.95% by weight and 0.05 to 50% by weight of a crosslinking agent having two or more ethylenically unsaturated bonds, and an acrylic resin. The present invention relates to a composition for a charge transport layer comprising: The present invention also relates to the composition for a charge transport layer, wherein the crosslinked polymer fine particles are polymerized by blending a component containing a styrene monomer as a monoethylenically unsaturated monomer and divinylbenzene as a crosslinker. The present invention relates to a composition for a charge transport layer obtained by the above method. The present invention also relates to the composition for a charge transport layer, which comprises a non-halogen solvent capable of dissolving an acrylic resin alone or in a mixed state. The present invention also relates to an electrophotographic photoreceptor having a charge transport layer using any of these charge transport layer compositions.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The crosslinked polymer fine particles used in the present invention are spherical gel particles having a three-dimensional network structure. The average particle size of the crosslinked polymer fine particles is 30 to 1000 nm, preferably 30 to 2 nm.
50 nm. In a crosslinked polymer fine particle having an average particle diameter of less than 30 nm, it is difficult to form a charge transport layer having a desired strength.On the other hand, in a crosslinked polymer fine particle having an average particle diameter of more than 1000 nm, a uniform charge transport layer is formed. Difficult to form. The average particle diameter is a weight average particle diameter measured with a submicron particle analyzer N4 (manufactured by Coulter Inc.). The crosslinked polymer fine particles increase the hardness of the coating film and improve the abrasion resistance by a pseudo crosslinking effect with the acrylic resin.

The crosslinked polymer fine particles used in the present invention are obtained by polymerizing a monoethylenically unsaturated monomer and a crosslinking agent having two or more ethylenically unsaturated bonds. Monoethylenically unsaturated monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene,
pn-butylstyrene, pt-butylstyrene, p
-N-hexylstyrene, pn-octylstyrene,
pn-nonylstyrene, pn-decylstyrene, p
Styrene monomers such as -n-dodecylstyrene, n-methoxystyrene p-phenylstyrene, p-chlorostyrene and 3,4-dichlorostyrene, ethylene, propylene and ethylenically unsaturated monoolefins such as butylene isoprene; Vinyl chloride, vinylidene chloride, vinyl bromide,
Vinyl halides such as vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl esters such as vinyl butyrate, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, N-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl o-chloroacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate ,
Isobutyl methacrylate, n-octyl methacrylate,
Dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate,
Α-methylene aliphatic monocarboxylic acid esters such as dimethylaminoethyl acrylate and diethylaminoethyl methacrylate, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether, 2-hydroxyethyl acrylate, methacrylic acid 2
Acrylic acid or methacrylic acid derivatives such as -hydroxyethyl and 2-hydroxypropyl methacrylate; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole; N-vinyl carbazole; N-vinyl Indole,
Other compounds such as N-vinyl compounds such as N-vinylpyrrolidone, vinyl naphthalene, acronitrile, methacrylonitrile, acrylamide, methacrylamide, acrylic acid, methacrylic acid, maleic acid, fumaric acid, and the like. Incidentally, two or more of these compounds may be used in combination.

Examples of the crosslinking agent include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene and derivatives thereof, allyl methacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, and trimethylolpropane triacrylate. 1,6-hexanediol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, N, N-divinylaniline, divinyl ether, divinyl sulfite, divinyl adipate,
Compounds having two or more ethylenically unsaturated bonds such as vinyl acrylate and vinyl methacrylate are exemplified. Note that two or more of these compounds can be used in combination.

It is preferable to use a styrene monomer, a methacrylic acid derivative, an acrylic acid derivative as the monoethylenically unsaturated monomer and an aromatic divinyl compound as the cross-linking agent. As
It is preferable to use crosslinked polymer fine particles using a styrene monomer and divinylbenzene as a crosslinker.

The monoethylenically unsaturated monomer and the cross-linking agent constituting the crosslinked polymer fine particles are 50 to 99.95% by weight, preferably 80 to 9% by weight of the monoethylenically unsaturated monomer.
9.9% by weight and a cross-linking agent of 0.05 to 50% by weight, preferably 0.1 to 20% by weight are blended so that the total amount becomes 100% by weight. If the amount of the crosslinking agent is less than 0.05% by weight, the degree of crosslinking of the polymer is insufficient, and the desired effect cannot be obtained. On the other hand, when the amount of the crosslinking agent exceeds 50% by weight, the crosslinked polymer fine particles aggregate, and thus the crosslinked polymer fine particles having a desired average particle diameter cannot be obtained.

In the present invention, the crosslinked polymer fine particles are prepared by subjecting the monoethylenically unsaturated monomer and the crosslinking agent to aqueous suspension polymerization, emulsion polymerization or nonaqueous dispersion polymerization in the presence of a polymerization initiator. You. Aqueous suspension polymerization includes, for example, oil-soluble polymerization initiators such as benzoyl peroxide and azobisisobutyronitrile in an aqueous medium, and polyvinyl alcohol, a cellulose derivative, and calcium phosphate in a suspending agent. It can be performed using: In the emulsion polymerization, for example, sodium persulfate, 2,2-azobis (isobutyramide) dihydrate is used as a polymerization initiator in an aqueous medium,
Hydrogen peroxide / sodium hydrogen sulfite and the like can be used by using sodium lauryl sulfate, sodium sulfosuccinate and the like as emulsifiers.

Non-aqueous dispersion polymerization includes, for example, n-hexane, n-hexane,
-In a hydrocarbon such as heptane, benzol peroxide, azobisisobutyronitrile as a polymerization initiator,
Dispersants such as 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) and the like, for example, K.E.
J. Barrett, ed., `` Dispersion Polymerization in Organic Media, '' John Wiley and Sons (1975), p. 108 (KEJ Barrett (Ed
it.) ″ Dispersion Po1ymerization in OrganicMedia ″ J
Poly (12-hydroxystearic acid) and poly (methyl methacrylate) described in Ohn Wi1ey & Sons (1975), P108)
And mercurylic acid).

In the present invention, the crosslinked polymer fine particles are used in an amount of 0.5 to 0.5 with respect to the total amount of the crosslinked polymer fine particles and the acrylic resin.
It is preferable to contain it in an amount of 50% by weight, particularly 0.5 to 10% by weight. If the content is less than 0.5% by weight, the effect of the wood invention may not be sufficiently achieved. On the other hand, if the content exceeds 50% by weight, the viscosity of the acrylic resin becomes too high, and film formation becomes difficult.

In the present invention, in order to mix the crosslinked polymer fine particles with the acrylic resin, the crosslinked polymer fine particles are previously dispersed in a monomer as a raw material of the acrylic resin, and the monomer is polymerized to form the acrylic resin. It is preferable to carry out by a method of synthesis, a method of mixing the acrylic resin and the crosslinked polymer fine particles in a solvent, or the like.

In the present invention, the acrylic resin is styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, pt- Butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, n-methoxy styrene p-phenyl styrene, p-chloro Styrene, 3,
Styrene monomers such as 4-dichlorostyrene, ethylene, propylene, butylene, ethylenically unsaturated monoolefins such as isoprene, vinyl chloride, vinylidene chloride, vinyl bromide, vinyl halides such as vinyl fluoride,
Vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate, dodecyl acrylate 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl o-chloroacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-methacrylate O-methylene aliphatic monocarboxylic acids such as octyl, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl acrylate and diethylaminoethyl methacrylate Vinyl ethers such as steles, vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; acrylic or methacrylic acid derivatives such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate; vinyl methyl Vinyl ketones such as ketone, vinyl hexyl ketone, methyl isopropenyl ketone, N-vinyl pyrrole, N-vinyl carbazole, N
-A polymer obtained by polymerizing one or two or more monoethylenically unsaturated monomers such as N-vinyl compounds such as vinyl indole and N-vinyl pyrrolidone, and vinyl naphthalene salts; Aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene and derivatives thereof, allyl methacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, trimethylolpropane triacrylate, 11,6-hexanediol dimethacrylate Having two or more ethylenically unsaturated bonds such as trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, N, N-divinylaniline, divinyl ether, divinyl sulfite, etc. That copolymers obtained by polymerization by blending the above monoethylenically unsaturated monomer may be mentioned a crosslinking agent.

The acrylic resin can be polymerized by a known polymerization method using a known polymerization initiator.
Further, the acrylic resin in the present invention can be used alone, but if necessary, it can be cross-linked in combination with an amino resin, an isocyanate compound or the like to increase the mechanical strength of the coating film such as hardness and toughness. As the amino resin, melamine resin, benzoguanamine resin, urea resin, and the like, tolylene diisocyanate, isophorone diisocyanate, and the like can be used.

The composition for a charge transporting layer of the present invention further contains a charge transporting substance. As the charge transporting substance, various known substances can be used. Examples of the charge transporting substance include fluorene, fluorenone, 2,7-dinitro-9-fluorenone, and 4H-indeno (1,2,6).
Thiophene-4-one, 3,7-dinitro-dibenzothiophene-5-oxide, 1-bromopyrene, 2-phenylpyrene, carbazole, 3-phenylcarbazole, 2-phenylindole, 2-phenylnaphthalene, oxazole, oxadiazole , Oxatriazole, triphenylamine, imidazole, chrysene,
Tetraphen, acridene, various hydrazones, styryl compounds, poly-N-vinylcarbazole, halogenated poly-N-vinylcarbazole, 1-phenyl-3-
(4-diethylaminostyryl) -5- (4-diethylaminophenyl) pyrazoline, polyvinylpyrene, 2-
Phenyl-4- (4-diethylaminophenyl) -5
Phenyloxazole, polyvinyl indoloquinoxaline, 1,1-bis (p-diethylaminophenyl)-
Examples include 4,4-diphenyl-1,3-butadiene, polyvinyl benzothiophene, polyvinyl anthracene, polyvinyl acridine, benzidine, polyvinyl pyrazoline, and derivatives thereof.

In the charge transport layer composition of the present invention,
If the boiling point of the solvent used is too low or too high, the thickness of the coating film becomes uneven when immersion coating is performed, and the characteristics vary depending on the obtained photoreceptor position. It is a problem. Therefore, a solvent having a boiling point of 35C to 170C is preferable, and a solvent having a boiling point of 40C to 155C is more preferable.

In order to make the coating film uniform in both morphology and composition, it is necessary that the solvent be capable of dissolving the acrylic resin and the above-described charge transporting substance. Examples of such a solvent include solvents such as methylene chloride, teratohydrofuran, methyl ethyl ketone, cyclohexanone, benzene, toluene, and xylene. These may be used alone or in combination of two or more.
The amount of the solvent used is preferably in the range of 300 to 900 parts by weight based on 100 parts by weight of the total of the charge transporting substance, the crosslinkable polymer particles, and the acrylic resin. If the amount is less than 300 parts by weight, the viscosity of the composition is too high.
It tends to be difficult to form a proper coating film. -Way,
If it exceeds 900 parts by weight, the viscosity of the composition tends to be too low and the thickness of the coating film tends to be too thin.

In the charge transporting layer composition of the present invention, the total amount of the crosslinkable polymer particles and the acrylic resin is based on 100 parts by weight of the charge transporting substance from the viewpoint of not deteriorating electrophotographic properties and film properties. On the other hand, it is preferably used in the range of 50 to 450 parts by weight.

The composition for a charge transport layer of the present invention may further contain known additives such as a plasticizer, a fluidity-imparting agent and a pinhole controlling agent, if necessary. Each of these additives is preferably used in an amount of 5 parts by weight or less based on 100 parts by weight of the charge transporting substance.

The present invention further relates to an electrophotographic photosensitive member having a charge transport layer formed using the composition for a charge transport layer prepared as described above. Hereinafter, a method for manufacturing the photoconductor will be described in detail.

The electrophotographic photoreceptor is obtained by forming a charge generating layer and a charge transport layer after providing an undercoat layer as necessary on a conductive substrate. As the conductive substrate, a metal such as aluminum, iron, copper, nickel or the like, or paper or plastic which has been subjected to conductive treatment is used in the form of a film, a sheet or a seamless belt. Also,
Plastic films, sheets and seamless belts in which metal foils such as aluminum are laminated can also be used. Metal can also be used as a drum.

On the conductive substrate as described above, a known undercoat layer which is usually used can be provided. As the undercoat layer, for example, titanium oxide, aluminum oxide, zirconia, titanic acid, zirconic acid, lanthanum lead,
Fine particles such as titanium black, silica, lead titanate, and barium titanate, and components such as polyamide resin, phenol resin, casein, melamine resin, benzoguanamine resin, polyurethane resin, epoxy resin, cellulose, and polyvinyl butyral resin can be used. . These fine particles and resins can be used alone or in combination of two or more. In particular, when the fine particles and the resin are used together, the resin is adsorbed on the fine particles and a smooth film can be obtained. Therefore, it is desirable to use the fine particles and the resin together.

As a method for forming an undercoat layer, a solution obtained by dispersing and dissolving the fine particles and / or resin in a solvent is applied onto a conductive substrate by a dip coating method, a spray coating method, a roll coating method, or the like.
It can be formed by coating using a coating method such as an applicator coating method or a wire bar coating method and drying.

Examples of the solvent used at this time include solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, toluene, ethyl acetate, toluene, xylene, cellosolve, methanol, isopropyl alcohol, isobutyl alcohol, and n-butyl alcohol. Can be The thickness of the undercoat layer is usually 0.01 to 20.0 μm, preferably 0.1 to 3 μm.
0 μm. When this thickness is less than 0.01 μm,
It becomes difficult to form an undercoat layer uniformly, and 20.0 μm
If it exceeds m, the electrophotographic properties tend to decrease.

After forming the undercoat layer as described above,
A charge generation layer and a charge transport layer are sequentially laminated and formed on this layer.

In the present invention, the photoconductive substance used in the charge generation layer includes azoxybenzene, disazo, trisazo, benzimidazole, polycyclic quinoline, indigoid, quinacridone, phthalocyanine, and the like. Known organic pigments, such as naphthalocyanine-based, pyrrolo-pyrrole-based, perylene-based, and methine-based organic pigments, which generate electric charge by light irradiation.

When the charge generation layer is formed using only the photoconductive substance, a vacuum deposition method or the like is used.
When the charge generation layer is formed using the photoconductive substance and other components, the photoconductive substance, a binder and a plasticizer, a curing catalyst, a fluidity imparting agent, a pinhole controlling agent, and the like are required. The additives used are uniformly dissolved in solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, ethyl acetate, cellosolve, methanol, isopropyl alcohol, isobutyl alcohol, n-butyl alcohol, and a mixed solvent thereof. Alternatively, a coating liquid for forming a charge generation layer which is dispersed is prepared, and the coating liquid is coated on the undercoat layer by a dip coating method, a spray coating method, a roll coating method, an applicator coating method, a coating method such as a wire bar coating method, or the like. Can be applied and dried to form a film.

As the binder, for example, silicone resin, polyamide resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, polystyrene resin, polymethacrylate resin,
Polyacrylamide resin, polybutadiene resin, polyisoprene resin, melamine resin, benzoguanamine resin,
Polychloroprene resin, polyacrylonitrile resin, ethyl cellulose resin, nitrocellulose resin, urea resin, phenol resin, phenoxy resin, polyvinyl butyral resin, formal resin, vinyl acetate resin, vinyl acetate / vinyl chloride copolymer, polyester carbonate resin, etc. Can be Also, heat and / or photo-curable resins can be used. In any case, there is no particular limitation as long as the resin is electrically insulating and can form a film in a normal state.

As described above, when the charge generation layer is formed using the photoconductive substance and other components, the binder resin in the charge generation layer is based on 100 parts by weight of the photoconductive substance. Preferably 5 to 200 parts by weight.
More preferably, it is 0 parts by weight. If the amount is less than 5 parts by weight, the film of the charge generation layer tends to be uneven, and the image quality tends to be poor. If it exceeds 200 parts by weight, the sensitivity tends to decrease and the residual potential tends to increase.

As the plasticizer, halogenated paraffin,
Dimethylnaphthalene, dibutylphthalate and the like can be mentioned. Examples of the curing catalyst include sulfonic acids such as methanesulfonic acid, dodecylbenzenesulfonic acid, and dinonylnaphthalenedisulfonic acid. Examples of the fluidity-imparting agent include Modaflow (trade name of Monsanto Chemical Co., Ltd.), Acronal 4F (trade name of BASF) and the like. Further, examples of the pinhole controlling agent include benzoin, dimethylphthalate and the like.
Each of these is preferably used in an amount of 5 parts by weight or less based on the photoconductive substance.

The thickness of the charge generation layer is usually from 0.01 to
It is 0.2 μm, preferably 0.1 to 0.8 μm. When the thickness is less than 0.01 μm, the charge generation layer is
When the thickness exceeds 2.0 μm, the electrophotographic properties tend to deteriorate. After the charge generation layer is formed as described above, the composition for the charge transport layer produced as described above is further coated on this layer by dip coating, spray coating, roll coating, applicator coating. , And is formed by coating using a coating method such as a wire bar coating method and drying. The thickness of the charge transport layer is usually 5 to 50 μm.
m, preferably 8 to 35 μm. This thickness is 5 μm
If less than 50 μm
If the ratio exceeds the above range, the electrophotographic properties tend to decrease.

In the electrophotographic photosensitive member according to the present invention, a protective layer may be further formed on the charge transport layer from the viewpoint of abrasion resistance. The thickness of the protective layer is 0.01 to 10 μm, preferably 0.1 to 3 μm. This thickness is 0.01μ
If it is less than 10 m, the effect of the protective layer is not obtained, and the durability is poor.
If it exceeds μm, the sensitivity tends to decrease and the residual potential tends to increase.

When printing is performed using the electrophotographic photoreceptor according to the present invention, after performing the charging and exposure in the same manner as in the prior art, development is performed, and the image is transferred onto plain paper and fixed.

[0041]

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto.

Each material used in the following examples is listed below. The abbreviation is shown in parentheses. (A) Photoconductive substance generating charge τ-type metal-free phthalocyanine (τ-H ₂ Pc) (manufactured by Toyo Ink Manufacturing Co., Ltd.)

(B) Charge transporting substance

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(A) MX 1970 for the undercoat layer (MX 1970) Solid content 100% by weight (manufactured by Nippon Rilsan Co., Ltd.) Melan 2000 (ML 2000) (butylated melamine resin having 4.0 bound formaldehyde and 1.0 methylol group) , Solid content 50% by weight (manufactured by Hitachi Chemical Co., Ltd.)

(B) Binder resin for charge generation layer Brominated phenoxy resin YPB-43 (YPB-43), solid content 40% by weight (manufactured by Toto Kasei Co., Ltd.)

(C) Binder resin for charge transport layer Polycarbonate resin having the following structure

Embedded image GPC having lexane 141-111 (L141), solid content of 100% by weight (manufactured by GE) and the following repeating unit
, A polyester resin having a molecular weight in terms of polystyrene of 53,000, Viron 290 (V-290), and a solid content of 10
0% by weight (Toyobo Co., Ltd.)

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Amino resin Melan 2000 (ML200
0, solid content 50% by weight) (same as for the undercoat layer) Amino resin Melan 365W (ML365, solid content 60)
Wt%) (manufactured by Hitachi Chemical Co., Ltd.)

Synthesis Example 1 Preparation of Poly (styrene / divinylbenzene) -based Crosslinked Polymer Fine Particle Dispersion I 300 g of ion-exchanged water, 3.5 of sodium lauryl sulfate
g and 0.5 g of 2,2'-azobis (isobutyramide) dihydrate were charged into a reaction vessel equipped with a receiving device, a nitrogen blowing tube, a thermocouple for temperature control, and a cooling tube, and were thoroughly dissolved while stirring. Was. Next, 29.7 g of styrene and 0.3 g of divinylbenzene (containing about 40% by weight of ethylvinylbenzene with a purity of 55% by weight and about 5% by weight of an unreacted mixture, the same applies hereinafter) were added thereto. The reaction was allowed to proceed for 5 hours, and then all of the reaction solution was added for 3 hours.
The mixture was poured into 2,000 g of methanol to aggregate the crosslinked polymer particles, reacted at 50 ° C. for 2 hours, and then filtered. The obtained filtration residue in a wet state with methanol is removed by azeotropic distillation with styrene, and the content of the crosslinked polymerized particles is adjusted to be 10% by weight to obtain a styrene dispersion of fine particles of crosslinked polymer. Was. The weight average diameter of styrene in the dispersion was measured with a submicron particle analyzer N4 (manufactured by Coulter), and was found to be 80 nm.

Synthesis Example 2 Preparation of Poly (styrene / divinylbenzene) -based Crosslinked Polymer Fine Particle Dispersion II 300 g of ion-exchanged water, 3.5 of sodium lauryl sulfate
g and 0.5 g of 2,2'-azobis (isobutyramide) dihydrate were charged into a reaction vessel provided with a stirrer, a nitrogen blowing tube, a thermocouple for temperature control, and a cooling tube, and dissolved well with stirring. Then, 28.4 g of styrene and 1.6 g of divinylbenzene (containing about 40% by weight of ethylvinylbenzene and about 5% by weight of an unreacted mixture in the following manner) were added at 80 ° C. with stirring. The reaction was performed for 5 hours. Then, all of the reaction solution was added to 3
The mixture was poured into 2,000 g of methanol to aggregate the crosslinked polymer particles, reacted at 50 ° C. for 2 hours, and then filtered. The obtained filtration residue in a wet state with methanol was removed by azeotropic distillation with styrene, and the content of the crosslinked polymer particles was adjusted to be 10% by weight to obtain a styrene dispersion of crosslinked polymer fine particles. . The weight average diameter of styrene in the dispersion was 200 nm when measured with a submicron particle analyzer N4 (manufactured by Coulter Inc.).

Synthesis Example 3 Preparation of Acrylic Resin a Toluene was charged into a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube, heated to 90 ° C., and then stirred in a nitrogen stream. A solution of 100 parts by weight of styrene monomer, 20 parts by weight of butyl methacrylate, and 3 parts by weight of azobisisobutyronitrile was added dropwise at 100 ° C.
Stirred for hours. Thereafter, a solution of 100 parts by weight of styrene monomer, 20 parts by weight of butyl methacrylate, and 0.6 parts by weight of azobisisobutyronitrile was added dropwise while maintaining the temperature at 90 ° C., and the mixture was stirred for 5 hours. The conversion was almost 100% by weight. The reaction solution was gradually heated to elute toluene, and the toluene was removed under reduced pressure, and the mixture was allowed to cool to obtain a transparent resin. Number average molecular weight is about 10,000,
The dispersity was 23. The glass transition temperature was 65 ° C. The average molecular weight is a number average molecular weight in terms of standard polystyrene determined by gel permeation chromatography analysis. The glass transition temperature was measured by a thermomechanical analysis method. Hereinafter, the measuring method is the same.

Synthesis Example 4 Preparation of Mixture of Crosslinked Polymer Fine Particles and Acrylic Resin b In the method for preparing an acrylic resin, 1 part of styrene dispersion I of crosslinked polymer fine particles was used instead of 100 parts by weight of styrene.
A mixture of crosslinked polymer fine particles and acrylic resin b was prepared in exactly the same manner as in Synthesis Method 3 except that 00 parts by weight was used.
The number average molecular weight of this resin could not be measured because it contained crosslinked polymer fine particles. The glass transition temperature of this resin is 76
° C.

Synthesis Example 5 Preparation of Mixture of Cross-Linked Polymer Fine Particles and Acrylic Resin C While stirring at, a solution of 120 parts by weight of a styrene monomer and 3 parts by weight of azobisisobutyronitrile was added dropwise, followed by stirring at 100 ° C. for 3 hours. Then again 90
A solution of 100 parts by weight of a styrene dispersion I of crosslinked polymer particles, 20 parts by weight of butyl methacrylate, and 0.6 parts by weight of azobisisobutyronitrile was added dropwise at a temperature of 5 ° C., and the mixture was transferred for 5 hours. The conversion was almost 100% by weight. The resulting reaction solution was gradually heated to elute toluene, and the toluene was removed under reduced pressure, followed by cooling to obtain a transparent resin. The number average molecular weight was about 10,000 and the degree of dispersion was 23. The glass transition temperature was 70 ° C.

Synthesis Example 6 Preparation of Mixture of Crosslinked Polymer Fine Particles and Acrylic Resin d In the method for preparing an acrylic resin, 100 parts by weight of the styrene dispersion liquid II of the crosslinked polymer fine particles of Synthesis Example 2 was used instead of 100 parts by weight of styrene. An acrylic resin d containing crosslinked polymer fine particles was prepared in exactly the same manner as in Synthesis Method 3 except for the above. The number average molecular weight of this resin could not be measured because it contained crosslinked polymer fine particles. The glass transition temperature of this resin was 76 ° C.

Example 1 70 g of MX 1970, 140 g of ML2000 and 4.2 g of trimellitic acid were added to methyl ethyl ketone 360
0 g was completely dissolved. This solution was applied on an aluminum drum (outer diameter 120 mm, length 486 mm, thickness 4 mm) by dip coating, dried at 120 ° C. for 30 minutes, and dried to a film thickness of 0.1 mm.
An undercoat layer of 3 μm was formed.

Next, 100 g of τ-H ₂ Pc, 200 g
Of YPB-43 and 3,700 g of tetrahydrofuran were dispersed using an ultrasonic disperser for 80 hours. The obtained coating liquid for a charge generation layer was applied on the undercoat layer by a dip coating method, and dried at 140 ° C. for 30 minutes to form a 0.3 μm-thick charge generation layer.

Next, a mixture of 140 g of PBD and 277 g of a crosslinkable polymer particle and acrylic resin b was dissolved and dispersed in 2400 g of tetrahydrofuran at 2400 g. This solution was applied on the charge generation layer having the undercoat layer by a dip coating method, and dried at 100 ° C. for 30 minutes to form a film having a thickness of 18 μm.
A μm charge transport layer was formed to form an electrophotographic photoreceptor.

Example 2 An undercoat layer and a charge generation layer were formed on an aluminum drum using the materials and operations described in Example 1. Next, 140
g of PBD and 277 g of a mixture of crosslinkable polymer particles and acrylic resin c were dissolved in 2400 g of tetrahydrofuran. This solution was applied on the charge generation layer having the undercoat layer by a dip coating method, and dried at 100 ° C. for 30 minutes to form a charge transport layer having a thickness of 18 μm, thereby forming an electrophotographic photosensitive member.

Example 3 An undercoat layer and a charge generation layer were formed on an aluminum drum using the materials and operations described in Example 1. Next, 140
g of PBD and 277 g of a mixture of crosslinkable polymer particles and acrylic resin d were dissolved and dispersed in 2400 g of tetrahydrofuran. This solution was applied on the charge generation layer having the undercoat layer by a dip coating method, and dried at 100 ° C. for 30 minutes to form a charge transport layer having a thickness of 18 μm, thereby forming an electrophotographic photosensitive member.

Comparative Example 1 An undercoat layer and a charge generation layer were formed on an aluminum drum using the materials and operations described in Example 1. Next, 140
g of PBD and 260 g of L141 were dissolved in 2400 g of tetrahydrofuran. This solution was applied on the charge generation layer having the undercoat layer by a dip coating method,
It was dried at 0 ° C. for 30 minutes to form a 17 μm-thick charge transport layer, thereby forming an electrophotographic photoreceptor.

Comparative Example 2 A subbing layer having a thickness of 0.3 μm was formed on an aluminum drum (outer diameter: 120 mm, length: 486 mm, thickness: 4 mm) using the materials and operations described in Example 1. Next, a charge generation layer having a thickness of 0.3 μm was formed on the undercoat layer using the substances and operations described in Example 1. Next, 140
g of PBD and 260 g of acrylic resin a were dissolved in 2400 g of tetrahydrofuran. This solution is applied on the charge generation layer having the undercoat layer by a dip coating method,
The resultant was dried at 100 ° C. for 30 minutes to form a charge transport layer having a thickness of 16 μm, thereby forming an electrophotographic photosensitive member.

Comparative Example 3 A subbing layer having a thickness of 0.3 μm was formed on an aluminum drum (outer diameter: 120 mm, length: 486 mm, thickness: 4 mm) using the materials and operations described in Example 1. Next, a charge generation layer having a thickness of 0.3 μm was formed on the undercoat layer using the substances and operations described in Example 1. Next, 140
g of PBD, 260 g of acrylic resin a and 21.6 g
Of silica fine particles R972 (trade name of Nippon Aerosil Co., Ltd.) was dissolved and dispersed in 2400 g of tetrahydrofuran. This solution was applied on the charge generation layer having the undercoat layer by a dip coating method, and dried at 100 ° C. for 30 minutes to form a charge transport layer having a thickness of 18 μm, thereby forming an electrophotographic photosensitive member.

The photoresponsiveness and image quality (initial and after printing at 100 kP) of the electrophotographic photosensitive members obtained in Comparative Examples and Examples were evaluated by the following methods.

The light responsiveness was measured by a light attenuation measurement (manufactured by Midoriya Electric Co., Ltd.
Using Cynthia 30), corona charging is performed so that the surface potential becomes -700 V, and light having a wavelength of 780 nm
The evaluation was based on the time required for V ₀ to become −350 V when irradiated with ms.

The image quality was evaluated using an image evaluator (negative charging, reversal developing method), fog, black spot,
Evaluation was made based on image density of white spots, filming, and black background. The surface potential was -700 V, and the bias potential was -600 V. The image density on a black background was measured using a Macbeth reflection densitometer (A Divisi
on of Kollmorgen Corporation). Table 1 summarizes the results of these evaluations.

[0065]

[Table 1]

When a bisphenol A type polycarbonate resin was used for the charge transport layer (Comparative Example 1), the photoresponsiveness was 1
8 ms. The initial image had many fog, black spots, and white spots, and the image density was 1.2. Therefore, this photoconductor was not subjected to the 100 kP printing test. When an acrylic resin containing no crosslinked polymer fine particles was used for the charge transport layer (Comparative Example 2), the photoresponsiveness was 18 ms. The images at the initial stage and after the 100 kP printing test were good, but 10
The film thickness reduction after the 0 kP printing test was as large as 4.2 μm. When a mixture of silica fine particles and acrylic resin a was used for the charge transport layer (Comparative Example 3), the photoresponsiveness was 17 ms. The initial image shows no fogging, no black spots, no white spots, no image streaks due to toner filming on the surface of the charge transport layer, and has excellent characteristics.
It was 4. However, the image after the 100 kP printing test contains
Image streaks occurred due to toner filming on the surface of the charge transport layer, and the decrease in film thickness after printing at 100 kP was as large as 4.0 μm.

On the other hand, the electrophotographic photosensitive members according to the present invention (Examples 1, 2 and 3) all have a photoresponsiveness of 18%.
ms. The initial image was good without fogging, black spots, white spots, and image streaks caused by toner filming on the surface of the charge transport layer, and the image density was 1.4.
The image after the 100 kP printing test was also good without fog, black spots, white spots, and image streaks due to toner filming on the surface of the transport layer, and had an image density of 1.4. In addition, the decrease in film thickness after the 100 kP printing test was as small as 2 μm or less, which proved to be excellent in abrasion resistance.

[0068]

The composition for a charge transport layer of the present invention and an electrophotographic photoreceptor using the composition can be obtained by mixing a charge transporting substance in a charge transport layer with a polyether sulfone resin and an amino resin as a binder. Since the state is considered to be uniform, when continuous printing is performed using a high-speed printer, fog, black spots, white spots,
This is a photosensitive member that produces excellent image quality without filming and has excellent wear resistance and a long printing life. Therefore, the electrophotographic photoreceptor of the present invention can be very advantageously applied to a printer that requires high-speed response, high image quality, and a high number of printed sheets.

Claims (4)

[Claims] 1. Monoethylenically unsaturated monomers 50 to 99.
95% by weight and 0.05 to 50% by weight of a crosslinking agent having two or more ethylenically unsaturated bonds, containing crosslinked polymer fine particles having an average diameter of 30 to 1000 nm obtained by polymerization and an acrylic resin. A composition for a charge transport layer. 2. The crosslinked polymer fine particles are obtained by mixing and polymerizing a component containing a styrene monomer as a monoethylenically unsaturated monomer and divinylbenzene as a crosslinking agent. A composition for a charge transport layer. 3. The charge transport layer composition according to claim 1, further comprising a non-halogen solvent capable of dissolving the resin according to claim 1 alone or in a mixed state. 4. An electrophotographic photoreceptor having a charge transport layer using the composition for a charge transport layer according to claim 1, 2 or 3.