JPH0675410A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide the electrophotographic sensitive body having good dark decay-restraining performance without regard to the kinds of phthalocyanine type photoconductors. CONSTITUTION:A photoconductive layer formed on a conductive substrate contains composite particles obtained by coating the surfaces of highly insulating particles with the phthalocyanine type photoconductive particles, and a binder resin and a hydrazone compound represented by formula in which R1 is an optionally substituted phenyl group or such a heterocyclic group; R2 is H, alkyl, or substituted aryl; each of R3 and R4 is, independently, alkyl, aryl, or aralkyl; and n is 0 or 1.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrophotographic photosensitive material. More specifically, the present invention relates to an electrophotographic light-sensitive material having improved dark decay.

[0002]

2. Description of the Related Art Generally, in electrophotography, the photoconductive layer surface of a photoconductor is charged and exposed to form an electrostatic latent image.
This is visualized with a developing solution and the visible image is directly fixed on the photoconductor to obtain a copy image, or the visible image on the photoconductor is transferred onto a transfer paper such as paper and the transferred image is transferred. There is a so-called PPC system in which a fixed image is obtained by fixing. Conventionally, amorphous selenium, cadmium sulfide or zinc oxide is generally used as a photoconductive material for forming a photoconductive layer of an electrophotographic photosensitive material used for this kind of purpose. However, amorphous selenium requires vapor deposition on a conductive support and is difficult to manufacture, and the vapor deposition film has no flexibility, and is highly toxic and requires careful handling.
It has the drawback of being expensive. On the other hand, in the case of cadmium sulfide or zinc oxide, the sensitivity depends on the mixing ratio of the binder resin to be bound on the support, so the proportion of the binder resin should be small in order to obtain a practical sensitivity. Inevitably, as a result, the mechanical strength such as flexibility, smoothness, hardness, wear resistance is low, and further there is a drawback that the characteristics are deteriorated by ozone and the like generated by corona discharge,
There were hygiene problems such as environmental pollution due to toxicity.

Various researches and developments have been carried out in order to solve these drawbacks and problems, and in recent years, for example, JP-A-50-38543.
JP-A-51-95852, JP-A-53-6
No. 4040, JP-A No. 53-83744 and the like propose a photoreceptor using a phthalocyanine photoconductive material. It is known that this type of photoconductor is excellent in processability and sensitivity, has no hygiene problem, and exhibits high sensitivity to light having a long wavelength such as a semiconductor laser.

In an electrophotographic material having a photosensitive layer formed by dispersing phthalocyanine photoconductive material powder in a binder resin on a substrate, highly insulating material particles are mixed in the photoconductive layer. This makes it possible to improve the sensitivity, but when used for printing plate applications, it has been a problem that the retention rate of dark decay decreases.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic light-sensitive material having an improved dark decay retention rate regardless of the type of phthalocyanine photoconductive material used.

[0006]

The electrophotographic photosensitive material of the present invention comprises a phthalocyanine photoconductive material comprising fine particles, and a highly insulating material comprising fine particles on one surface of a conductive support. A hydrazone compound, an electrophotographic photosensitive material having a photoconductive layer containing a binder resin as a main component, wherein the phthalocyanine-based photoconductive material particles and the highly insulating material particles have a high insulating property. The material particles are composed of composite particles whose surfaces are coated with phthalocyanine photoconductive material particles, and the hydrazone compound is a compound represented by the following general formula (1).

[0007]

[Chemical 2]

That is, the electrophotographic photosensitive material of the present invention is
When forming the photoconductive layer, a composite particle in which phthalocyanine-based photoconductive material particles are immobilized by physical or chemical means on the surface of highly insulating material particles is prepared, and a hydrazone compound is also used in combination. As a result, it is possible to improve the retention rate of dark decay.

The materials constituting the present invention will be described in detail below. The hydrazone compound used in the present invention is a compound represented by the above general formula (1), and specific compounds thereof are exemplified below.

[0010]

[Chemical 3]

[0011]

[Chemical 4]

[0012]

[Chemical 5]

These compounds can be used alone or in combination of two or more. By adding these compounds in a weight ratio of 1/10 or less to the phthalocyanine-based photoconductive material particles, dark decay can be improved. Adding more than 1/10 results in rather increased dark decay.

The highly insulating material particles used in the present invention include, as organic materials, polyolefin resin, nylon resin, acrylic resin, polyvinyl chloride resin, rubber, epoxy resin, Teflon resin, etc., or as inorganic materials calcium carbonate, silica. Any material having a volume resistance of 10 ¹² Ωm or more such as mica, mica, alumina, and magnesium oxide may be used, and these materials are pulverized or pulverized at the synthesis stage to be used alone or as a mixture. be able to. The average particle size of the insulating material particles is 50μ
It is preferably m or less.

As the phthalocyanine photoconductive material particles composed of fine particles used in the present invention, any of phthalocyanine known per se and derivatives thereof can be used, and specifically, aluminum phthalocyanine, beryllium phthalocyanine, magnesium phthalocyanine, Calcium phthalocyanine, zinc phthalocyanine, gallium phthalocyanine, cadmium phthalocyanine, indium phthalocyanine, lanthanum phthalocyanine, samarium phthalocyanine, europium phthalocyanine, dysprosium phthalocyanine, yttetrium phthalocyanine, ruthenium phthalocyanine, copper phthalocyanine, vanadium phthalocyanine, tin phthalocyanine, titanyl phthalocyanine, Phthalocyanine, uranium Roshianin, manganese phthalocyanine, iron phthalocyanine, cobalt phthalocyanine, nickel phthalocyanine, rhodium phthalocyanine, palladium phthalocyanine, vanadyl phthalocyanine, platinum phthalocyanine, metal phthalocyanines such as antimony phthalocyanine are exemplified. Further, the central nucleus of phthalocyanine may be not a metal atom but a metal halide having a valence of 3 or more.

Derivatives of metal or metal-free phthalocyanine such as copper-4-aminophthalocyanine, iron polyhalophthalocyanine, cabartohexaphenylphthalocyanine, tetraazophthalocyanine, tetramethylphthalocyanine, and dialkylaminophthalocyanine are preferable. Can be used alone or in combination.

The phthalocyanine derivative in which the hydrogen atom of the benzene nucleus in the phthalocyanine molecule is substituted with at least one electron withdrawing group selected from the group consisting of a nitro group, a cyano group, a halogen group, a sulfone group and a carboxyl group. And a phthalocyanine and at least one kind of an unsubstituted phthalocyanine compound selected from the phthalocyanine compound are mixed with an inorganic acid capable of forming a salt with them, and a phthalocyanine photoconductive material obtained by precipitating with water or a basic substance. Material compositions can also be used. In this case, the electron-withdrawing group-substituted phthalocyanine derivative has 1 to 16 substituents in one molecule.
Any one of these can be used, and the composition ratio of the electron-withdrawing group-substituted phthalocyanine derivative to the other non-substituted phthalocyanine compound is such that the number of the substituents is 0 per unit phthalocyanine molecule in the composition. The number is preferably 001 to 2, preferably 0.002 to 1. 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,
Examples thereof include hydroiodic acid, hydrofluoric acid and hydrobromic acid.

Of the above-mentioned photoconductive material particles, those particularly suitable for the present invention include metal-free phthalocyanine, titanyl phthalocyanine, copper phthalocyanine and derivatives thereof, for example, nuclear electron-withdrawing group substituted derivatives.
The particle size of the primary particles is preferably 0.01 μm to 5 μm.

As the binder resin used in the present invention,
It is possible to use all known binder resins such as known thermoplastic resins, photocurable resins, and photoconductive resins, which are themselves electrically insulating. 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, styrene-butadiene blocks. Copolymer, polycarbonate, vinyl chloride-vinyl acetate copolymer, cellulose ester, thermoplastic resin such as polyimide, epoxy resin, urethane resin, silicone resin, phenol resin, melamine resin,
A thermosetting resin such as a xylene resin alkyd resin or a thermosetting acrylic resin, a photocurable resin, an electron beam curable resin, a photoconductive resin such as poly-N-vinylcarbazole, polyvinylpyrene or polyvinylanthracene. It is desirable that these binder resins have a volume resistance of 10 ¹² Ωm or more when measured alone.

Further, in the present invention, a sensitizer and an antioxidant can be used if desired. As the sensitizer used in the present invention, trinitroanthracene, 2,
Polycyclic or heterocyclic nitro compounds such as 4,7-trinitrofluorenone, acid anhydrides such as phthalic anhydride and trimellitic anhydride, quinones such as anthraquinone, aromatic amines such as tetramethyl-p-phenylenediamine and tetra. Examples thereof include nitrile compounds such as cyanoethylene, pyrazoline compounds, triphenylmethane compounds and styryl compounds. The amount of sensitizer used in the present invention is
A suitable amount is 0.1 to 30% by weight based on phthalocyanine. As the antioxidant used in the present invention, various compounds known per se can be used, but hindered phenol-based antioxidants are particularly preferable. In the electrophotographic light-sensitive material of the present invention, by using a sensitizer or an antioxidant, it is possible to improve moisture resistance and repeated sensitivity changes without lowering sensitivity.

As the conductive support used in the present invention, a foil or plate of copper, aluminum, silver, iron, nickel or the like in the form of a sheet or a drum, or a paper or plastic film laminated with a resin film, etc. Vacuum deposition of these metals, electroless plating,
Alternatively, a sheet surface coated with an electrolyte and subjected to a conductive treatment is used.

There is no particular limitation on the method for producing the composite particles of the phthalocyanine-based photoconductive material particles and the crosslinked polymer resin particles of the present invention. For example, in a bonding solution prepared by dissolving a binder resin in a solvent. A dispersion liquid in which photoconductive material particles and a sensitizer are dispersed, is sprayed into a fluidized system in which crosslinked polymer resin particles are suspended, whereby a photoconductive material powder is formed on the surface of the crosslinked polymer resin particles, A coating method for coating with a sensitizer, pre-dried crosslinked polymer resin particles, photoconductive material particles, and a sensitizer are mixed, and this mixture is mixed with a general pulverizer (for example, a ball mill, a roll mill, an ang mill). , Sand mill, etc.) to attach the photoconductive material particles and the sensitizer to the surface of the crosslinked polymer resin particles, and the method of placing the mixed powder in a high-speed air stream to collide with the wall surface. Then, mechanical energy is applied to the particles, whereby the photoconductive material particles and the sensitizer are physically adhered and immobilized on the surface of the crosslinked polymer resin particles. . In the present invention, the content of the phthalocyanine-based photoconductive material in the composite particles is preferably 5 to 80% by weight.

In the electrophotographic light-sensitive material of the present invention, the composite particles prepared as described above are mixed and dispersed in a binder resin together with a solvent to prepare a photosensitive coating liquid, which is prepared by a conductive support. It is prepared by directly coating the above or on the intermediate layer formed on the support, drying and further heat treatment to form a photoconductive layer.

The mixing ratio of the phthalocyanine-based photoconductive material particles and the binder resin in the present invention is preferably 5 to 100 parts by weight, more preferably 5 to 100 parts by weight of the phthalocyanine-based photoconductive material particles, relative to 100 parts by weight of the binder resin. Is 10 to 60 parts by weight. The amount of phthalocyanine-based photoconductive material particles is 100.
When the amount is more than 5 parts by weight, the sensitivity is improved, but the dark decay is remarkably increased to make it difficult to retain the electric charge. Conversely, when the amount of the phthalocyanine-based photoconductive material particles is less than 5 parts by weight, the dark decay is reduced. However, the sensitivity decreases.

The electrophotographic photosensitive material using the composite particles of the present invention may be the electrophotographic photosensitive material comprising only the photoconductive layer of the present invention, and further includes a barrier layer, an insulating layer,
Alternatively, it may be an electrophotographic photosensitive material in which a photoconductive layer made of another photoconductive material is laminated.

[0026]

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

Example 1 10 parts by weight of ε-type copper phthalocyanine (manufactured by BASF: L6700F, average particle diameter 0.5 μm), 1 part by weight of the hydrazone compound represented by the formula (2), low density polyethylene particles (manufactured by Sumitomo Seika: L Mixing 60 parts by weight (-1080, average particle diameter 5 μm) and using a high-speed air impact device (Nara Machinery: Hybridization System), the rotor speed was 1
The treatment was performed under conditions of 5000 RPM and a treatment time of 10 minutes to obtain composite particles in which the surface of polyethylene particles was coated with copper phthalocyanine particles and a hydrazone compound. To 70 parts by weight of the composite particles, 60 parts by weight of a polyester resin (manufactured by Toyobo: Byron 200) is added, 250 parts by weight of a mixed solvent of toluene: tetrahydrofuran (1: 1) is added as a solvent, and a dispersion treatment is performed with a paint conditioner for 30 minutes. , A photoconductive coating was prepared. This coating material was applied on a support laminated with aluminum foil so as to have a thickness of about 20 μm, and dried at 100 ° C. for 1 minute to prepare an electrophotographic photosensitive material.

The obtained electrophotographic light-sensitive material was measured with an electrophotographic sensitivity measuring device (SP-428 manufactured by Kawaguchi Denki Co., Ltd.) to evaluate the performance. The measurement conditions were a charging voltage of 5.6 kv, a dark decay time of 10 seconds, and a tungsten lamp (10lux) for a light irradiation time of 20 seconds. The performance evaluation was a charging potential Vs (V) immediately after charging and 10 seconds later. Dark decay rate DD
(%), And the exposure amount Eh (lux · sec) until the potential dropped to half of the surface potential at the time of irradiating light was measured. The results are shown in Table 1.

Example 2 An electrophotographic photosensitive material was prepared in the same manner as in Example 1 except that the hydrazone compound represented by the formula (12) was used in place of the hydrazone compound represented by the formula (2). . Table 1 shows the evaluation results obtained in the same manner as in Example 1.

Example 3 10 parts by weight of ε-type copper phthalocyanine (manufactured by BASF: L6700F, average particle diameter 0.5 μm), 1 part by weight of the hydrazone compound represented by the formula (2), low density polyethylene particles (manufactured by Sumitomo Seika: L -1080, average particle diameter 5 μm) 60 parts by weight, polyester resin (Toyobo: Byron 200) 1
Parts by weight, toluene 200 parts by weight, tetrahydrofuran 2
00 parts by weight are mixed and dispersed by ultrasonic waves, and a spray dryer (manufactured by Nisshin Engineering: Dispacoat) is used to spray pressure 3 Kg / cm ² , spray liquid supply amount 500 g / h, blower air amount for drying. 2m ³ / mi
n and the heater temperature was 75 ° C. to obtain composite particles in which the surface of polyethylene particles was coated with copper phthalocyanine. To 70 parts by weight of the composite particles, 60 parts by weight of polyvinyl butyral resin (Sekisui Kasei: S-REC BLS) was added, 250 parts by weight of ethanol was further added as a solvent, and a dispersion treatment was performed with a paint conditioner for 10 minutes.
A photoconductive paint was prepared. Using this paint, a photoreceptor was prepared in the same manner as in Example 1. Table 1 shows the evaluation results obtained in the same manner as in Example 1.

Comparative Example 1 An electrophotographic photosensitive material was prepared in the same manner as in Example 1 except that the hydrazone compound was not added to the photoconductive coating. Table 1 shows the evaluation results obtained in the same manner as in Example 1.

Comparative Example 2 An electrophotographic photosensitive material was prepared in the same manner as in Example 3 except that the hydrazone compound was not added to the photoconductive paint. Table 1 shows the evaluation results obtained in the same manner as in Example 1.

[0033]

[Table 1]

Example 4 In place of the ε-type copper phthalocyanine of Example 1, α-type titanyl phthalocyanine (manufactured by Sanyo Dye Co., Ltd .: average particle size 0.2 μm)
An electrophotographic photosensitive material was produced in the same manner as in Example 1 except that m) was used. Table 2 shows the evaluation results obtained in the same manner as in Example 1.

Comparative Example 3 An electrophotographic photosensitive material was prepared in the same manner as in Example 4, except that the hydrazone compound was not added to the photoconductive coating. Table 2 shows the evaluation results obtained in the same manner as in Example 1.

[0036]

[Table 2]

[0037]

INDUSTRIAL APPLICABILITY The electrophotographic photosensitive material of the present invention has good dark decay maintaining performance regardless of the type of photoconductive material, and is used for general copying machines, laser printers, photosensitive plate materials and the like. When it does, it shows excellent characteristics.

Claims (1)

[Claims] 1. A phthalocyanine-based photoconductive material formed of fine particles, a highly insulating material formed of fine particles, a hydrazone compound, and a binder resin as main components on one surface of a conductive support. An electrophotographic photosensitive material having a photoconductive layer containing, wherein the phthalocyanine photoconductive material particles and the highly insulating material particles, the surface of the highly insulating material particles is a phthalocyanine photoconductive material particles. An electrophotographic photosensitive material comprising coated composite particles, wherein the hydrazone compound is a compound represented by the following general formula (1). [Chemical 1]