JPH0690525B2 - Photoconductor - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an electrophotographic photoreceptor, in particular, a photosensitive layer formed by dispersing particles of a photoconductive material in a binder made of an insulating polymer material on a substrate. The present invention relates to an electrophotographic photosensitive member formed.

2. Description of the Related Art In recent years, for example, JP-A-50-38543 and JP-A-51-95852 are available.
JP-A-53-64040, JP-A-53-83744 and the like propose a photoreceptor having a photosensitive layer in which a phthalocyanine photoconductive material is dispersed in a binder.

In this type of electrophotographic photoreceptor, it is difficult for electrons generated inside the photosensitive layer to be conducted to the surface of the photosensitive layer, and as a result, it takes time for the surface charge to disappear, that is, for the electrostatic latent image to be formed (induction effect). There were problems such as problems, gradation, humidity resistance, and deterioration of performance due to repeated use (printing durability).

Among the above problems, a method of coating the surface of a photoconductive organic pigment, for example, phthalocyanine with an appropriate resin such as a polypeptide resin has been proposed as a method for improving printing durability (JP-A-54-4137). Issue). However, in general, coating a photoconductive organic pigment with a resin is apt to cause a reduction in the sensitivity of the photoconductor, and is not necessarily a satisfactory method.

OBJECT OF THE INVENTION It is an object of the present invention to improve the printing durability and humidity resistance of a phthalocyanine photoreceptor without causing a decrease in sensitivity.

Structure of the Invention The present invention provides a phthalocyanine photoconductor in which a photosensitive layer obtained by dispersing a phthalocyanine photoconductive material powder in a binder resin is formed on a substrate. The present invention relates to a phthalocyanine photoreceptor which is coated or adsorbed with at least one material selected from transport materials and antioxidants.

As the phthalocyanine-based photoconductive material used in the present invention, any of phthalocyanines and derivatives thereof known per se can be used, and specifically, copper, silver, beryllium, magnesium, calcium, gallium, zinc, cadmium, barium, Mercury, aluminum, indium, lanthanum, neodymium, samarium, europium,
Gadolinium, dysprosium, holmium, sodium, lithium, ytterbium, lutetium, titanium,
Examples include tin, hafnium, lead, thorium, vanadium, antimony, chromium, molybdenum, uranium, manganese, iron, cobalt, nickel, rhodium, palladium, osmium and platinum. Further, the central nucleus of the phthalocyanine may be not a metal atom, but a metal halide having a valence of 3 or more. Furthermore, copper-4-aminophthalocyanine, iron polyhalophthalocyanine, cobalt hexaphenylphthalocyanine and tetraazophthalocyanine,
Metal-free phthalocyanine derivatives such as tetramethylphthalocyanine and dialkylaminophthalocyanine can be used. These can be used alone or in combination.

Phthalocyanine derivative in which hydrogen atom of benzene nucleus in phthalocyanine molecule is substituted with at least one electron-withdrawing group selected from the group consisting of nitro group, cyano group, halogen atom, sulfone group and carboxyl group, and phthalocyanine and said phthalocyanine Use a phthalocyanine-based photoconductive material composition obtained by mixing at least one kind of an unsubstituted phthalocyanine compound selected from compounds with an inorganic acid capable of forming a salt with them and precipitating with water or a basic substance. You can also
In this case, the electron-withdrawing group-substituted phthalocyanine derivative is
Any number of 1 to 16 substituents in one molecule can be used, and the composition ratio of the electron-withdrawing group-substituted phthalocyanine derivative to the other unsubstituted phthalocyanine compound is such that the number of the former substituents is It is preferable that the number of the phthalocyanine molecules in the composition be 0.001 to 2, preferably 0.002 to 1 per molecule. As the inorganic acid capable of forming a salt with the phthalocyanine compound used in producing the phthalocyanine-based photoconductive material composition, sulfuric acid, orthophosphoric acid, chlorosulfonic acid, hydrochloric acid, hydroiodic acid, hydrofluoric acid, Examples thereof include hydrobromic acid.

Among the above-mentioned photoconductive materials, metal-free phthalocyanine, copper phthalocyanine and derivatives thereof, such as nuclear electron-withdrawing group substituted derivatives, are particularly preferable for achieving the object of the present invention.

As the electrically insulating binder resin in the present invention, all known electrically insulating thermoplastic resins, thermosetting resins, photocurable resins, photoconductive resins, and other binders can be used. .

Examples of suitable binder resins include, but are not limited to, saturated polyester resins, polyamide resins, acrylic resins, ethylene-vinyl acetate copolymers, ion-crosslinked olefin copolymers (ionomers), styrene- Thermoplastic binders such as butadiene block copolymer, polycarbonate, vinyl chloride-vinyl acetate copolymer, cellulose ester, polyimide; epoxy resin, urethane resin,
Thermosetting binder such as silicone resin, phenol resin, melamine resin, xylene resin, alkyd resin, and thermosetting acrylic resin; photocurable resin; photoconductivity of poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, etc. Resin.

These electrically insulating resins are individually measured to be 1 × 10 ¹⁴ Ω ・
It is desirable to have a volume resistance of cm or more.

As the conductive support, a foil or plate of copper, aluminum, silver, iron, nickel or the like in the form of a sheet or a drum is used, or these metals are vacuum-deposited on a plastic film or electroless plating. The one used is used.

As the charge transport material, generally known compounds such as hydrazone compounds, oxadiazole compounds, triphenylmethane compounds, pyrazoline compounds and styryl compounds can be used. Among them, the hydrazone compound represented by the following general formula [I] is particularly preferable.

[Wherein R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are an alkyl group, an aralkyl group or an aryl group which may have a substituent, a condensed polycyclic group which may have a substituent, A Is an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group, and n represents a number of 1 or 2. R ₂ and R ₃ may combine with each other to form a ring. These compounds are described, for example, in JP-A-54-150128, JP-A-55-46760, JP-A-55-154955, and JP-A-55-52063.

The charge transport material may be polyvinyl carbazole, polyvinyl anthracene, or the like, which is a polymer itself. By coating with a phthalocyanine-based photoconductive material, sensitivity and repeatability are improved, and ozone resistance, printing resistance and humidity resistance are improved.

In the present invention, the coating or adsorption treatment of the phthalocyanine photoconductive material may be carried out in place of the charge transport material, or at the same time with an antioxidant.

The antioxidant is not particularly limited, but hindered phenol antioxidants are preferable. Specific examples include Irganox 1222, 565, 1035, 1010, 1076, 1098 (manufactured by Ciba Geigy), Seanox M-200, 220 (manufactured by Shiraishi Calcium Co., Ltd.), and antioxidant NKF (manufactured by Bayer). .

When the charge transport material and the antioxidant are used in combination, the effect of preventing deterioration of the photoconductive material due to ozone resistance or the like is significantly improved.

In one embodiment of the present invention, it is prepared by previously dispersing at least one material selected from a phthalocyanine-based photoconductive material powder, a charge transport material and an antioxidant, and then drying.

In the embodiment of the present invention, a phthalocyanine photoconductive material powder is mixed with at least one material selected from a charge transport material and an antioxidant, and the mixture is heated to a temperature equal to or higher than the melting point of the charge transport material. It is prepared by fixing a charge-transporting material or the like to a conductive material.

In another embodiment of the present invention, the phthalocyanine photoconductive material powder is surface coated with at least one material selected from a charge transport material and an antioxidant.

In the case of the present invention, it is preferable to perform surface coating with at least one material selected from a charge transport material and an antioxidant, and then disperse the binder resin using a decomposing solvent that does not dissolve the binder resin. However, a part of it is adsorbed by the photoconductor material, so that it shows some effect.

Also, Japanese Patent Application No. 58-164160 proposes a method of sensitizing a photoreceptor obtained by dispersing a phthalocyanine-based photoconductive material in a resin by adding a large amount of a hydrazone compound. It may be surface-coated or adsorbed and may be dispersed in a resin, in which case they may be the same or different. It is desirable to be different.

In the photoreceptor of the present invention, the photoconductive material whose surface is coated with at least one material selected from the charge transport material and the antioxidant as described above is kneaded and dispersed in the binder resin together with the solvent to be photosensitively coated. It is provided by preparing a solution, coating it directly on a conductive substrate or coating it on an intermediate layer formed thereon, and then heat treating it to form a photosensitive layer.

The amount of the surface coating charge transport material used in the present invention is 0.5 to 50% by weight, preferably 1 to 30% by weight, based on phthalocyanine.

The amount of antioxidant used in the present invention is based on phthalocyanine.
It is 0.01 to 30% by weight, preferably 0.1 to 20% by weight.

When used in combination with an antioxidant and a charge transport material for surface coating, the total amount of both is 0.5 to 80% by weight based on phthalocyanine,
A range of 1 to 50% by weight is suitable.

In a particularly preferred embodiment, the weight ratio of the antioxidant to the surface-coating charge transport material is 9: 1 to 2: 8, and the total amount of both is 1 to 50% by weight based on phthalocyanine.

Regarding the blending ratio of the phthalocyanine photoconductive material and the binder resin, the sensitivity improves as the former amount increases,
On the other hand, when the amount of the former decreases, the dark decay decreases but the sensitivity decreases, so that the amount of photoconductive material is bound. 5 to 100 parts by weight, preferably 10 to 60 parts by weight, is suitable for 100 parts by weight of the agent resin.

EFFECTS OF THE INVENTION When the surface-coated photoconductive material of the present invention is made into a coating material together with a binder resin, it exhibits good fluidity such as low viscosity of the coating material and small tendency to exhibit structural viscosity. Due to its cohesiveness, it has excellent storage stability, and the electrophotographic photoreceptor obtained from this photoconductor material has good electrophotographic characteristics, such as photosensitivity, repetitiveness, humidity resistance and printing durability. Shows excellent properties in terms of properties.

In the electrophotographic photosensitive member using the photoconductive material of the present invention, not only the electrophotographic photosensitive layer according to the present invention, but also the electrophotographic photosensitive layered with a barrier layer, an insulating layer and a photosensitive layer of another photoconductive material are laminated. It may be the body.

Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1 50 parts by weight of ε-type copper phthalocyanine and 5 parts by weight of N-ethylcarbazole-3-aldehyde diphenylhydrazone were dispersed together with 50 parts by weight of tetrahydrofuran, dried, and then tetrahydrofuran was evaporated to form a phthalocyanine surface-coated with a hydrazone compound. Got

15 parts by weight of the obtained surface-coated phthalocyanine, 28 parts by weight of a thermosetting acrylic resin (Acridic A405: manufactured by Dainippon Ink Co., Ltd.), melamine resin (Super Beckamine J820: manufactured by Dainippon Ink Co., Ltd.) 7 Parts by weight, 20 parts by weight of p-diethylaminobenzaldehyde diphenylhydrazone and a mixed solvent of methyl isobutyl ketone: cellosolve acetate (1: 1) (which does not dissolve the coating layer (hydrazone) very much) are kneaded with a ball mill for 48 hours, A photoconductive paint was prepared, and this paint was applied on an aluminum substrate to a thickness of about 15 μm to prepare a photoreceptor.

Example 2 50 parts by weight of ε-type copper phthalocyanine, 10 parts by weight of p-dibenzylaminobenzaldehyde methylphenylhydrazone and 0.5 part by weight of an antioxidant (Irganox 1076: manufactured by Ciba Geigy) are dispersed in 50 parts by weight of tetrahydrofuran and then dried. Tetrahydrofuran was evaporated to obtain a phthalocyanine surface-coated with a hydrozone compound.

15 parts by weight of the obtained surface-coated phthalocyanine, thermosetting acrylic resin (Acridic A405: Dainippon Ink and Chemicals, Inc.)
28 parts by weight, melamine resin (Super Beckamine J82)
0: Dainippon Ink and Chemicals, Inc. 7 parts by weight, p-diethylaminobenzaldehyde diphenylhydrazone 20 parts by weight and methyl isobutyl ketone: cellosolve acetate (1:
The mixed solvent of 1) (which does not dissolve the coating layer very much) is kneaded in a ball mill for 48 hours to prepare a photoconductive coating, and the coating is applied on an aluminum substrate to a thickness of about 15 μm. The body was made.

Example 3 50 parts by weight of ε-type copper phthalocyanine and 10 parts by weight of p-diethylaminobenzaldehyde diphenylhydrazone were dispersed in 40 parts by weight of methyl ethyl ketone and then dried to evaporate methyl ethyl ketone to obtain a phthalocyanine surface-coated with a hydrazone compound. It was

15 parts by weight of the obtained surface-coated phthalocyanine, 28 parts by weight of a thermosetting acrylic resin (HR620: manufactured by Mitsubishi Rayon Co., Ltd.), 7 parts by weight of melamine resin (Uban 20HS: manufactured by Mitsui Toatsu Co., Ltd.), p-diethylamino A photoconductive paint was prepared by kneading 20 parts by weight of benzaldehyde diphenylhydrazone and a mixed solvent of methyl isobutyl ketone: cellosolve acetate (1: 1) with a ball mill for 48 hours. This paint was applied on an aluminum substrate to a thickness of about 15 μm to prepare a photoreceptor.

Comparative Example 1 An electrophotographic photosensitive member was produced in exactly the same manner as in Example 1 except that the ε-type copper phthalocyanine particles were not coated with the charge transport material.

Comparative Example 2 1,2 parts of 50 parts by weight of ε-type copper phthalocyanine and 5 parts by weight of a polycarbonate resin (Panlite K1300: Teijin Chemicals Ltd.)
Dispersed in 50 parts by weight of dichloroethane. Next, 100 parts by weight of 1,2-dichloroethane was added to dilute, and n-
After gradually adding hexane, the precipitated fine particles were filtered, separated and dried to obtain a phthalocyanine surface-coated with polycarbonate.

15 parts by weight of the obtained surface-coated phthalocyanine, thermosetting acrylic resin (Acridic A405: Dainippon Ink and Chemicals, Inc.)
28 parts by weight, melamine resin (Super Beckamine J82)
0: Dainippon Ink and Chemicals, Inc. 7 parts by weight, p-diethylaminobenzaldehyde diphenylhydrazone 20 parts by weight and methyl isobutyl ketone: cellosolve acetate (1:
Knead the mixed solvent of 1) for 48 hours using a ball mill,
A photoconductive paint was prepared, and this paint was applied on an aluminum substrate to a thickness of about 15 μm to prepare a photoreceptor.

Example 4 50 parts by weight of copper phthalocyanine and 0.2 parts by weight of tetranitro copper phthalocyanine were dissolved in 300 parts by weight of 98% concentrated sulfuric acid with sufficient stirring. The dissolved liquid is poured into 3000 parts by weight of water to deposit a composition of copper phthalocyanine / tetranitrocopper phthalocyanine. After that, it is washed with water and dried at 120 ° C. under reduced pressure.

Next, 10 parts by weight of this composition was added to N-ethylcarbazole-3.
-Aldehyde benzyl phenylhydrazone (1 part by weight) and tetrahydrofuran (10 parts by weight) were added, dispersed, dried, and tetrahydrofuran was evaporated to obtain a phthalocyanine surface-coated with a hydrazone compound.

10 parts by weight of the obtained surface-coated phthalocyanine, 28 parts by weight of a thermosetting acrylic resin (HR620: manufactured by Mitsubishi Rayon Co., Ltd.),
7 parts by weight of melamine resin (Uban 20HS: manufactured by Mitsui Toatsu Co., Ltd.), 20 parts by weight of p-diethylaminobenzaldehyde diphenylhydrazone and a mixed solvent of methyl isobutyl ketone: cellosolve acetate (1: 1) are kneaded for 48 hours using a ball mill. Then, a photoconductive paint was prepared, and this paint was applied on an aluminum substrate to a thickness of about 15 μm to prepare a photoreceptor.

Example 5 After 50 parts by weight of the copper phthalocyanine / tetranitrocopper phthalocyanine composition obtained in Example 4 and 8 parts by weight of bis (2-methyl-4-diethylaminophenyl) -cyclohexylmethane were dispersed in 50 parts by weight of tetrahydrofuran,
It was dried to obtain a phthalocyanine surface-coated with a diphenylmethane compound.

10 parts by weight of the obtained surface-coated phthalocyanine, 28 parts by weight of thermosetting acrylic resin (HR620: manufactured by Mitsubishi Rayon Co., Ltd.), 7 parts by weight of melamine resin (Uban 20HS: manufactured by Mitsui Toatsu Co., Ltd.), p-diethylamino 20 parts by weight of benzaldehyde diphenylhydrazone and cellosolve acetate (which does not dissolve the coating layer) were added and kneaded for 48 hours using a ball mill to prepare a photoconductive coating. This paint was applied on an aluminum substrate to a thickness of about 15 μm to prepare a photoreceptor.

Comparative Example 3 An electrophotographic photosensitive member was produced in exactly the same manner as in Example 4 except that the phthalocyanine particles were not coated with the charge transport material.

Comparative Example 4 Without coating the phthalocyanine particles with the charge transport material,
An electrophotographic photoreceptor was prepared in the same manner as in Example 4 except that N-ethylcarbazole-3-aldehydebenzylphenylhydrazone was used instead of p-diethylaminobenzaldehyde diphenylhydrazone.

Example 6 Instead of N-ethylcarbazole-3-aldehyde benzylphenylhydrazone, an antioxidant (IRGANOX 10
76: manufactured by Ciba-Geigy Co., Ltd.), and a photoconductor was prepared in exactly the same manner as in Example 4.

The obtained photoconductor was incorporated into a commercially available powder image transfer type electrophotographic copying machine (EP450Z manufactured by Minolta Camera Co., Ltd.), and the surface potential of the photoconductor immediately after being applied to the photoconductor surface by a corona discharge of +6.5 KV. Vo (V), decay rate DDR ₁ (%) of surface potential after standing for 1 second in the dark, and exposure amount E _1/2 required for reducing the surface potential after exposure to half the initial surface potential (Lux ・ se
c) and the surface potential Vo and the sensitivity E _1/2 when the charging-exposure-static elimination were repeated 3000 times were measured. The results are shown in Table-1. As is clear from the results in Table 1, the photoreceptor of the present invention has no deterioration in sensitivity and is superior to the comparative example in the result of repetitive characteristics and is superior to general copying machines and laser printers. It was a phthalocyanine photoreceptor showing characteristics.

Claims (1)

[Claims] 1. A photoconductor having a photoconductive layer in which phthalocyanine photoconductive material powder is dispersed in a binder resin, wherein the phthalocyanine photoconductive material powder comprises a charge transport material and an antioxidant. At least one selected
A phthalocyanine photoconductor characterized by being coated or adsorbed with one material.