JPH02196242A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent increase/decrease of residual potential due to repeating of charging and exposing the electrophotographic sensitive body by using polycarbonate-polystylene grafted copolymer with specified mean molecular weight and composition ratio as a binder resin for the photosensitive layer when the photosensitive layer is provided on a conductive supporting body to constitute the electrophotographic sensitive body. CONSTITUTION:A polymer film with vapor-deposited metal such as Al, Au, Ag, Cu, Ni, etc., is used for the conductive supporting body, on which a charge generating layer comprising azo pigment, perylene pigment, polycyclic quinone pigment, etc., with a solvent is applied to 0.1 - 2.0mum thickness. The compounding ratio of these charge generating agents and the binder resin is controlled to 1:(0.1 - 3). Oxasole, triazine or hydrazone and the binder resin are used with compounding ratio of 1 : (0.1 - 3) to form the charge transfer layer of 10 - 50mum thickness. The binder resin is such a resin containing polycarbonate-polystylene grafted copolymer with mean molecular weight of >=5,000, and the compsn. ratio of polymn. is specified to 10/90 - 90/10.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor containing a polycarbonate/polystyrene (PC/PSt) graft copolymer in a binder resin. .

[Prior art and problems to be solved by the invention] Electrophotography is a technology that applies the physical phenomenon of photoconductivity, and consists of repeating a series of operations such as charging, exposure, development, transfer, fixing, and cleaning. Currently, copying machine (PPC)
It is widely used in optical printers, etc. In recent years, organic materials have been attracting attention as an alternative to conventional inorganic materials such as Se, CdS, and ZnO for electrophotographic photoreceptors. In order to improve sensitivity, durability, etc., this organic photoreceptor may be of a single-layer type, in which a charge generation material and a charge transport material are included in one layer, or a charge generation layer and a charge transport layer. A function-separated laminated type in which functions are separated has been proposed, and improvements have been made to the charge generating material, charge transporting material, and binder resin that constitute these materials.

Regarding the binder resin, in the case of a functionally separated laminated type, the binder resin for the charge generation layer is one that has strong adhesion to the conductive support and uniformly disperses the charge generation material, and does not reduce charge generation efficiency. As a binder resin for the charge transport layer,
A material that has good compatibility with charge transporting materials and abrasion resistance against contact with paper, toner, or cleaning blades, has excellent charging properties as a photoreceptor, and does not affect sensitivity is desirable; In the case of molds, the binder resin should have strong adhesion to the conductive support and uniform dispersion of the charge generating material, as well as compatibility with the charge transporting material and contact with paper, toner, or cleaning blade. What is desired is a material that has good abrasion resistance, excellent charging properties as a photoreceptor, and does not affect sensitivity.

However, polycarbonate, polystyrene, polyester, boribi, rubutyral, etc. have been commonly used as binder resins for known photoreceptors.
These photoreceptors have problems such as decreased sensitivity, increased residual potential, and decreased charging potential during electrical repetition of charging and exposure, as well as decreased charging performance and increased residual potential due to pre-exposure fatigue. was there.

[Means to solve the problem]

The inventors of the present invention have conducted intensive studies to improve the above-mentioned problems and to obtain an electrophotographic photoreceptor with high sensitivity and high durability. It was discovered that the photoreceptor is excellent in terms of sensitivity and durability, leading to the present invention.

That is, the present invention is an electrophotographic photoreceptor comprising a photosensitive layer provided on a conductive support, characterized in that the photosensitive layer contains a polycarbonate/polystyrene (PC/PSt) graft copolymer as a binder resin. The present invention provides an electrophotographic photoreceptor.

Examples of the PC/Psi graft copolymer of the present invention include JP-A-63-159415 and JP-A-63-1.
It can be produced from an aromatic polycarbonate resin having an unsaturated end group and a styrenic polymer or a styrene monomer according to Method 6 described in Japanese Patent No. 96612.

In the present invention, this PC/PSt graft copolymer is used as a binder resin for a photosensitive layer consisting of a single-layer photoconductive layer or a laminated photosensitive layer consisting of a charge generation layer and a charge transport layer. In terms of film formability, adhesion, and stability of charging potential, the average molecular weight of the PC/PSt graft copolymer is preferably 5000 or more, and the composition weight ratio is -10/90. ~90/10, preferably 20/8O-==80/20, more preferably 30/70 to 70/30 to obtain an excellent photoreceptor with high sensitivity, stable charging potential, and low residual potential. Can be done.

In addition, in the present invention, pc/PSt is used as the binder resin.
Blend systems of graft copolymers and other resins can also be used. In this case, good results are obtained when the PC/PSt graft copolymer is contained in the binder resin in an amount of at least 5% by weight, preferably 10% by weight or more. The resin to be blended may be any resin as long as it is compatible with the PC/PSt graft copolymer, for example,
Acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, epoxy resin, polyester resin, alkyd resin, polycarbonate, poly V-+/N, polyurethane, polyimide resin, vinylidene chloride resin, polyvinyl Acecool resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol, water trI polyester, nitrocellulose,
Known resins such as casein can be used.

Next, each constituent material used in the present invention will be explained in detail.

As the conductive support, metals such as aluminum, gold, silver, copper, and nickel, metal-deposited polymer films, metal-laminated polymer films, and the like can be used in the form of drums or sheets.

In the case of a laminated electrophotographic photoreceptor in which a photosensitive layer consisting of a charge generation layer and a charge transport layer is provided on a conductive support, the charge generation material used in the charge generation layer is one that emits light of a specific wavelength. Any material, whether organic or inorganic, may be used as long as it absorbs and efficiently generates a charge.In particular, organic charge-generating materials such as azo pigments, bisazo pigments, trisazo pigments, and perylene may be used. Pigments, polycyclic quinone pigments, metal phthalocyanine and metal-free phthalocyanine pigments, thiapyrylium salts, squareium salts, azulenium salt pigments, etc. can be used, but are not limited to these. These organic pigments are mainly produced by adding an organic solvent to a binder resin and dispersing it using a ball mill, sand mill, attritor, ultrasonic method, etc., and then coating it on a conductive support. A generation layer can be formed.

The thickness of this charge generation layer is 0.1 to 2.0In@
, preferably 0.2 to 1.0. Further, the blending weight ratio of the charge generating material and the binder resin in the charge generating layer is preferably about 1:0.1 to 3:1.

The charge transport material used in the charge transport layer must have a high charge injection efficiency from the charge generation layer, a high charge mobility within the charge transport layer, and a good compatibility with the binder resin. Anything is fine. Examples include, but are not limited to, derivatives such as oxazole, oxadiazole, triazine, pyrazoline, hydrazone, benzothiazole, carbazole, imidazole, and styryl. A charge transport layer can be formed by dissolving these charge transport materials together with a binder resin in a suitable organic solvent and coating them on the charge generation layer.

The thickness of this charge transport layer is suitably 10 to 50 pm, preferably 10 to 30 tm. Further, the compounding weight ratio of the charge transport material and the binder resin in the charge transport layer is t:o, i
~3 is preferable.

Examples of organic solvents that can be used to prepare coating solutions for the charge generation layer and the charge transport layer include alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, N,N-dimethylformamide, and N. , amides such as N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, esters such as methyl acetate, ethyl acetate, chloroform, methylene chloride, dichloroethylene, carbon tetrachloride , aliphatic halogenated hydrocarbons such as trichloroethylene, or aromatics such as benzene, toluene, xylene, and chlorobenzene.

As a coating method for each layer, a bar coater, an applicator, a spray coater, a dip coater, a blade coater, a spin coater, a calendar coater, a gravure coater, etc. are used.

Also, in the case of a single-layer electrophotographic photoreceptor using a single leading tN as a photosensitive layer on a conductive support, the above-mentioned charge generating material and charge transporting material may be used together with a PC/pst graft copolymer. It can be prepared by dissolving or dispersing it in an appropriate organic solvent, coating it on a conductive support, and drying it.

In addition, the electrophotographic photoreceptor of the present invention may include a conductive or insulating protective layer on the surface layer, and an adhesive layer (subbing layer) or intermediate layer for the purpose of improving adhesion between each layer. may be provided.

Resins used for the undercoat layer, intermediate layer and protective layer include polyethylene, polypropylene, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, epoxy resin, polyester resin, alkyd resin, polycarbonate, polystyrene,
Polyurethane, polyimide resin, vinylidene chloride resin,
Polyvinyl acetal resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol, water-soluble polyester,
Known resins such as dicellulose and casein can be used, as well as the PC/PSt graft copolymer used as the binder resin in the present invention. The thickness of the undercoat layer, intermediate layer, and protective layer is 0.01=10I! m
, preferably 0.05 in 2 tm.

Conductive support obtained as above/charge generation layer/
The electrophotographic photoreceptor of the present invention consists of a charge transport layer,
When the photoreceptor surface is negatively charged and exposed to light after charging, holes generated in the charge generation layer in the exposed area are injected into the charge transport layer, and then reach the surface and neutralize the negative charge, causing a decrease in the surface potential. As a result, an electrostatic latent image is created between the unexposed areas.

Then, in the development step, positively charged toner adheres to the negatively charged electrostatic latent image area, and this is transferred and fixed onto the paper to be printed out.

Further, in the present invention, conductive support/charge transport layer/
It is also possible to produce an electrophotographic photoreceptor having a structure that generates charge. In this case, when the surface of the photoreceptor is positively charged and exposed after charging, electrons generated in the charge generation layer in the exposed area neutralize the positive charges on the surface of the photoreceptor, and holes are generated in the charge transport layer. through which it flows to the support. In this way, an electrostatic latent image is created in the unexposed area. Then, in the development step, negatively charged toner adheres to the positively charged electrostatic latent image area, and this is transferred and fixed onto the paper to be printed out.

Furthermore, for a single-layer type electrophotographic photoreceptor having a conductive support/photoconductive layer structure, the same process as above is carried out by charging the surface of the photoreceptor with positive or negative charges.

〔Effect of the invention〕

The electrophotographic photoreceptor of the present invention configured as described above can be charged,
This has the effect of eliminating phenomena such as an increase in residual potential and a decrease in charged potential due to repeated exposure.

〔Example〕

The electrophotographic photoreceptor of the present invention will be specifically explained below with reference to Examples and Comparative Examples.

The polycarbonate/polystyrene graft copolymer used in the examples was synthesized according to the method disclosed in JP-A-63-196612, and had a number average molecular weight of 15.000.5.
0,000.5,000.23,000.25 ,00
0 (measured by GPC, calculated as polystyrene) was used.

Example-1 X on a polyester film deposited with aluminum
Type-free metal phthalocyanine (pastogenBlue)
8120B, manufactured by Dainippon Ink & Chemicals ■) 3 g, vinyl chloride-vinyl acetate resin (S-LEC C1 manufactured by Sekisui Chemical ■)
A coating solution prepared by dispersing 3 g of cyclohexa2 in 100 g of cyclohexane 2 for 3 hours using a paint shaker was applied with a wire bar and dried to form a charge generation layer with a thickness of 0.5.

Next, 4-dibenzylamino-2-methylbenzaldehyde 1, agephenylhydrazone (CTC-191,
10g of polycarbonate/polystyrene graft copolymer (average molecular weight: 115,000. Composition weight ratio: -60/40) 10g of 1,4-dioxane 8
0 g, apply this to the previously formed charge generation layer using an applicator, and dry to obtain a film thickness of 20! A charge transport layer of lIm was formed to produce a laminated electrophotographic photoreceptor.

The electrophotographic properties of the thus produced electrophotographic photoreceptor were evaluated as follows using an electrostatic copying paper tester EPA-8100 (manufactured by Kawaguchi Denki Seisakusho).

That is, using the static method, the initial potential V of the surface.

Adjust the corona charging voltage so that it is around -800V, leave it in a dark place for 2 seconds, irradiate it with light with a wavelength of 790n The amount El/□, residual potential V,) was measured.

Furthermore, when the above operation is repeated 5000 times, Vo, R
9El/□+vr was measured.

These results are shown in Table-1.

Comparative Example-1 On a polyester film deposited with aluminum,
Type-free metal phthalocyanine (Fas togenBlue)
8120B, manufactured by Dainippon Ink & Chemicals ■) 3 g.

A coating solution prepared by dispersing 3 g of vinyl chloride-vinyl acetate resin (S-LEC C9 manufactured by Sekisui Chemical Co., Ltd.) in 100 g of cyclohexanone using a paint shaker for 3 hours was applied with a wire bar, dried, and a charge was generated with a film thickness of 0.5 μ. formed a layer. Next, 4-dibenzylamino-2-methylbenzaldehyde 1,1-diphenylhydrazone (CTC-1
91, made by Seinan Kaori ■) Log, polycarbonate/
Instead of polystyrene graft copolymer, 10 g of polycarbonate resin (Lexan 141-111, manufactured by Engineering Plastics ■) was mixed with 80 g of 1.4-dioxane.
This was applied onto the previously formed charge generation layer using an applicator and dried to form a charge transport layer having a thickness of 201 M, thereby producing a laminated electrophotographic photoreceptor.

The photoreceptor thus produced was evaluated in the same manner as in Example-1, and the results are shown in Table-1.

Comparative Example-2 On a polyester film deposited with aluminum,
Type-free metal phthalocyanine (Fast, ogenBlue
A coating solution prepared by dispersing 3 g of vinyl chloride-vinyl acetate resin (S-LEC C, manufactured by Lil Water Kagaku Co., Ltd.) in 100 g of cyclohexanone using a vent shaker for 3 hours. was applied with a wire bar and dried to form a charge generation layer with a thickness of 0.5-. Next, 4-dibenzylamino-2-methylbenzaldehyde 1,1-diphenylhydrazone (CTC-1
91, manufactured by Anan Perfume Co., Ltd.) Log, polycarbonate/
Instead of polystyrene graft copolymer, 10g of polystyrene (Styron 666, manufactured by Asahi Kasei Corporation) was added at 1.4
- Dissolved in 80 g of dioxane, applied it with an applicator onto the previously formed charge generation layer, and dried to form a film with a thickness of 20 g.
A charge transport layer of m was formed to produce a laminated electrophotographic photoreceptor.

The photoreceptor thus produced was evaluated in the same manner as in Example-1, and the results are shown in Table-1.

Example-2 On a polyester film coated with aluminum,
Type-free metal phthalocyanine (FastogenBlue)
812OB, manufactured by Dainippon Ink & Chemicals ■) 3 g, vinyl chloride-vinyl acetate resin (S-LEC C9 manufactured by Sekisui Chemical ■)
A coating solution prepared by dispersing 3 g of the sample in 100 g of cyclohexanone using a vent shaker for 3 hours was applied with a wire bar and dried to form a charge generation layer with a thickness of 0.5 -.

Next, 4-dibenzylamino-2-methylbenzaldehyde-1,1-diphenylhydrazone (CTC-191
, manufactured by Anan Kaori ■) 10g, polycarbonate/polystyrene graft copolymer (average molecular weight 50,000.m)
Molding amount ratio - 60/40) Dissolve 10g in 80g of 1,4-dioxane (7. Apply this on the previously formed charge generation layer with an applicator and dry it to form a charge transport layer with a film thickness of 20/ffi. A laminated electrophotographic photoreceptor was manufactured.

The photoreceptor thus produced was evaluated in the same manner as in Example-1, and the results are shown in Table-1.

Example-3 On a polyester film on which aluminum was vapor-deposited
Type-free metal phthalocyanine (FastogenBlue)
812OB, manufactured by Dainippon Ink & Chemicals ■) 3 g, vinyl chloride-vinyl acetate resin (S-LEC C9 manufactured by Sekisui Chemical ■)
A coating solution prepared by dispersing 3 g of cyclohexanone in 100 g of cyclohexanone for 3 hours using a vent shaker was applied with a wire bar and dried to form a charge generation layer with a thickness of 0.5 μm.

Next, 4-dibenzylamino-2-methylbenzaldehyde-1,1-diphenylhydrazone (CTC-191
, manufactured by Anan Kaori ■) 10g, polycarbonate/polystyrene graft copolymer (average molecular weight 5000. Composition weight ratio -80/20) Log 1.4-dioxane s
og, and applied it on the previously formed charge generation layer using an applicator and dried to form a charge transport layer with a thickness of 20 μm, thereby producing a laminated electrophotographic photoreceptor.

The photoreceptor thus produced was evaluated in the same manner as in Example-1, and the results are shown in Table-1.

Example 4 “Polyester film with aluminum vapor deposited” Second,
X-type metal-free phthalocyanine (FastogenBlue
A coating solution prepared by dispersing 3 g of vinyl chloride-vinyl acetate resin (S-LEC C1 manufactured by Sekisui Chemical Co., Ltd.) in 100 g of cyclohexanone for 3 hours using a paint shaker was applied using a wire bar. , and was dried to form a charge generation layer having a thickness of 0.5 mm. Next, 4-dibenzylamino-2-methylbenzaldehyde-1,1-diphenylhydrazone (CTC-19
1. 10g of polycarbonate/polystyrene graft copolymer (average molecular weight 23,000, composition weight ratio -40/60) and polyester resin (Pylon 2)
00. Blend system (manufactured by Toyobo Co., Ltd.) (binder resin 100
Contains 80 parts by weight of PC/PS t-graft copolymer and 20 parts by weight of polyester resin) 10g to 1,
Dissolved in 80 g of 4-dioxane, applied this to the previously formed charge generation layer using an applicator, and dried to obtain a film thickness of 2.
A 0- charge transport layer was formed to produce a laminated electrophotographic photoreceptor.

The photoreceptor thus produced was evaluated in the same manner as in Example-1, and the results are shown in Table-1.

Example-5 On a polyester film deposited with aluminum,
Type-free metal phthalocyanine (Fas togenBlue)
8120B, manufactured by Dainippon Ink & Chemicals ■) 3g, 4-
dibenzylamino-2-methylbenzaldehyde-1,
1-diphenylhydrazone (CTC-191.

Prepared by dissolving Log in 80 g of 1.4-dioxane and dispersing it in a paint shaker for 3 hours. The coating solution was applied with an applicator and dried to form a photoconductive layer with a thickness of 20 m, thereby producing a single-layer electrophotographic photoreceptor.

The photoreceptor thus produced was evaluated in the same manner as in Example-1, and the results are shown in Table-1.

Comparative Example-3 On a polyester film deposited with aluminum,
Type-free metal phthalocyanine (Fas togenBlue)
8120B, manufactured by Dainippon Ink & Chemicals ■) 3 g.

4-Dibenzylamino-2-methylbenzaldehyde-
1,1-diphenylhydrazone (CTC-191゜Anan Kaori ■) 10g, polycarbonate resin (instead of polycarbonate/polystyrene graft copolymer)
Lexan 141-111. Engineering Plastics ■) was dissolved in 80 g of 1,4-dioxane, and further dispersed for 3 hours using a paint shaker. A separately prepared coating solution was applied with an applicator, dried, and a film thickness of 20
- A photoconductive layer was formed to produce a single-layer electrophotographic photoreceptor.

The photoreceptor thus produced was evaluated in the same manner as in Example-1, and the results are shown in Table-1.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer provided on a conductive support, characterized in that the photosensitive layer contains a polycarbonate/polystyrene graft copolymer as a binder resin. body. 2. The electrophotographic photoreceptor according to claim 1, wherein the polycarbonate/polystyrene graft copolymer has an average molecular weight of 5,000 or more. 3. The polycarbonate/polystyrene composition weight ratio of the polycarbonate/polystyrene graft copolymer is 10/
The electrophotographic photoreceptor according to claim 1 or 2, which has a ratio of 90 to 90/10.