JPH0675407A - Electrophotographic photosensitive material - Google Patents

Abstract

(57) [Summary] [Object] To provide an electrophotographic photosensitive material having good sensitivity regardless of the kind of the phthalocyanine photoconductive material. [Electron] comprising a conductive support, and a photoconductive layer mainly composed of composite particles in which the surface of crosslinked polymer resin particles is coated with phthalocyanine photoconductive material particles and a binder resin. Photographic material.

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 photosensitive material having improved sensitivity.

[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 photosensitive material having a photoconductive layer formed by dispersing a phthalocyanine photoconductive material powder in a binder resin on a support, the resolution of the latent image can be improved. Will lead to improvement.
As one means for improving the sensitivity, it is possible to improve the sensitivity by mixing highly insulating particles in the phthalocyanine-based photoconductor, but further improvement in the sensitivity is required with the progress of hardware. There is.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic photosensitive material having improved sensitivity regardless of the type of phthalocyanine-based photoconductive material used.

[0006]

The electrophotographic photosensitive material of the present invention comprises a phthalocyanine photoconductive material comprising fine particles, and a crosslinked polymer resin comprising fine particles on one surface of a conductive support. An electrophotographic photosensitive material having a photoconductive layer containing a binder resin as a main component, wherein the crosslinked polymer resin particles and the phthalocyanine photoconductive material particles are the surface of the crosslinked polymer resin particles. Is composed of composite particles coated with phthalocyanine-based photoconductive material particles. That is, the electrophotographic photosensitive material of the present invention is a composite particle in which phthalocyanine photoconductive material particles are immobilized on the surface of the crosslinked polymer resin particles by physical or chemical means when forming the photosensitive layer. And the composite particles are dispersed in a binder resin to improve the sensitivity.

The materials constituting the present invention will be described in detail below. The crosslinked polymer resin particles composed of fine particles used in the present invention may be crosslinked polystyrene resin, crosslinked acrylic resin, crosslinked CMC, etc., as long as they have a volume resistance of 10 ¹² Ωm or more. Powdered, or pulverized into fine particles individually,
Alternatively, they can be mixed and used. The average particle size of the crosslinked polymer resin particles is preferably 50 μm 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 nitro group, cyano group, halogen group, sulfone group and 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, such as 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 is formed into a sheet shape or a drum shape, or a paper or a plastic film laminated with a resin film. 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 produced as described above are mixed and dispersed in a binder resin together with a solvent to prepare a photosensitive coating solution, 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 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 photoconductive material particles with respect 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 an electrophotographic photosensitive material comprising only the photoconductive layer of the present invention, and further comprises 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.

[0019]

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 size 0.5 μm), 2, as a sensitizer
A mixture of 1 part by weight of 4,5,7-tetranitro-9-fluorenone and 60 parts by weight of crosslinked polystyrene particles (SBX-4, average particle size 4 μm) were mixed to obtain a high-speed air impact device ( Rotational speed of rotor 1500 using Nara Machinery: Hybridization system)
The treatment was carried out under conditions of 0 RPM and a treatment time of 10 minutes to obtain composite particles in which the surface of the crosslinked polystyrene particles was coated with copper phthalocyanine and a sensitizer. 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 paint is applied to a support laminated with aluminum foil so as to have a thickness of about 20 μm,
An electrophotographic photosensitive material was produced by drying at 100 ° C. for 1 minute.

The obtained electrophotographic light-sensitive material was measured with an electrophotographic sensitivity measuring instrument (Kawaguchi Denki: SP-428) 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 Electrons were prepared in the same manner as in Example 1 except that crosslinked acrylic resin particles (MBX-5 manufactured by Sekisui Kasei, average particle size 5 μm) were used in place of the crosslinked polystyrene resin particles of Example 1. A photographic light-sensitive material was produced. 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), crosslinked polystyrene particles (manufactured by Sekisui Kasei: SBX-4, average particle diameter 4 μm) 60
Parts by weight, polyester resin (manufactured by Toyobo: Byron 20
0) 1 part by weight, 200 parts by weight of toluene, and 200 parts by weight of tetrahydrofuran are mixed and subjected to ultrasonic dispersion treatment,
Using a spray dryer (manufactured by Nisshin Engineering: Dispacoat), spray pressure 3 Kg / cm ² , spray liquid supply amount 500 g / h, blower air amount for drying 2 m ³ / m
In, the treatment was carried out under the conditions of a heater temperature of 75 ° C. to obtain composite particles in which the surface of the crosslinked polystyrene particles was coated with copper phthalocyanine particles. Polyvinyl butyral resin (Sekisui Kasei: S-REC BLS) 60 was added to 70 parts by weight of the composite particles.
Then, 250 parts by weight of ethanol was added as a solvent, and dispersion treatment was performed for 10 minutes with a paint conditioner to prepare a photoconductive paint. An electrophotographic photosensitive material was prepared in the same manner as in Example 1 using this coating material. Table 1 shows the evaluation results obtained in the same manner as in Example 1.

Comparative Example 1 An electrophotographic image was obtained in the same manner as in Example 1 except that low density polyethylene particles (L-1080, manufactured by Sumitomo Seika Co., Ltd., average particle size 5 μm) were used in place of the crosslinked polystyrene particles of Example 1. A light-sensitive material was prepared. Table 1 shows the evaluation results obtained in the same manner as in Example 1.

Comparative Example 2 Electrons were produced in the same manner as in Example 3 except that low density polyethylene particles (L-1080, manufactured by Sumitomo Seika Co., Ltd., average particle size 5 μm) were used in place of the crosslinked polystyrene particles of Example 3. A photographic light-sensitive material was produced. Table 1 shows the evaluation results obtained in the same manner as in Example 1.

[0026]

[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 diameter 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 Instead of the crosslinked polystyrene resin particles in Example 4, low density polyethylene particles (Sumitomo Seika: L-108) were used.
An electrophotographic photosensitive material was prepared in the same manner as in Example 4, except that the average particle size was 0, and the average particle size was 5 μm). Table 2 shows the evaluation results obtained in the same manner as in Example 1.

[0029]

[Table 2]

[0030]

INDUSTRIAL APPLICABILITY The electrophotographic photosensitive material of the present invention has good sensitivity regardless of the type of photoconductive material, and when used in a general copying machine, laser printer, photosensitive plate material or the like. It exhibits excellent characteristics.

Claims (1)

[Claims] 1. A photoconductive material comprising, on one surface of a conductive support, a phthalocyanine-based photoconductive material composed of fine particles, a crosslinked polymer resin composed of fine particles, and a binder resin as main components. An electrophotographic light-sensitive material having a layer formed,
The electrophotographic photosensitive material, wherein the crosslinked polymer resin particles and the phthalocyanine-based photoconductive material particles are composite particles in which the surface of the crosslinked polymer resin particles is covered with phthalocyanine-based photoconductive material particles. .