JPH02196244A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain uniform copies which are free from fogging even at and under a low temp. and low humidity by using a specific polymethylene ester resin for an under coating layer and specifying the mol. wt. thereof and coating thickness at the time of successively laminating the under coating layer and photosensitive layer on a conductive base body to form the electrophotographic sensitive body. CONSTITUTION:A sheet or cylinder formed by depositing Al, Cr, etc., by evaporation on Al, Ni, Cu, stainless steel or plastic sheet is used for the conductive base body 1 and the photosensitive layer 5 consisting of a charge generating layer 3 and a charge transfer layer 4 is laminated via the under coating layer 2 thereon. Polyvinyl alcohol, polyester, polymethyl methacrylate, etc., are used by being dispersed in a binder solvent as the charge generating material. A hole or electron transfer material having a polycylic arom. compd., such as anthracene or pyrene in the side chain is used for the charge transfer material. The polymethylene ester resin expressed by the general formula I is used for the under coating layer 2. The mol. wt. thereof is regulated to 3 to 100,000 and the coating thickness to 0.5 to 10mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor having a specific subbing layer in its layer structure.

[Conventional technology]

An electrophotographic photoreceptor is used several times to several dozen times through cycles of charging, exposure, development, transfer, cleaning, and neutralization. In this case, if a photosensitive layer is provided directly on the conductive substrate, a problem arises in that the photosensitive layer peels off from the conductive substrate during a multi-sheet copying cycle, shortening the life of the photoreceptor. Further, due to repeated corona charging, the photosensitive layer suffers dielectric breakdown and pinholes are formed, resulting in white spots on copies.

In order to overcome these drawbacks, it has been generally known to provide an undercoat layer between the conductive substrate and the photosensitive layer of an electrophotographic photoreceptor. That is, polyvinyl alcohol has been used as an undercoat layer in JP-A-58-105155, and in JP-A-49-69332 and JP-A-52-1.
0138 contains maleic acid resin, which is disclosed in JP-A-60-662.
58 uses nylon resin, JP-A No. 62-280854 uses polyvinyl pyrrolidone, and JP-A No. 62-28086 uses polyvinyl pyrrolidone.
5 discloses a mixture of 8-nylon, titanium oxide, tin oxide and antimony, and JP-A-61-80158 discloses a resin containing a hydrazone compound. However, none of them have sufficient properties, such as poor adhesion between the conductive substrate and the photosensitive layer, residual potential increases due to repeated charging and exposure, and ground burrs occurring at low temperatures and low humidity. There was a drawback to that.

[Problem to be solved by the invention]

The object of the present invention is to provide good image quality without deterioration of charging performance and no increase in residual potential even after repeated use, and therefore no decrease in image density or occurrence of texture blur, especially under low temperature and low humidity conditions. An object of the present invention is to provide an electrophotographic photoreceptor with excellent environmental stability.

[Failure to solve the problem]

That is, the present invention provides an electrophotographic photoreceptor comprising an undercoat layer and a photosensitive layer sequentially laminated on a conductive substrate, in which the undercoat layer is made of a polymethylene ester resin represented by the following general formula (I). The polymethylene ester resin represented by general formula (1), which is an electrophotographic photoreceptor characterized by It can be obtained by

The polymethylene ester resin is highly flexible and has excellent adhesion to the conductive substrate and the photosensitive layer, and the photosensitive layer will not peel off even after repeated use. Furthermore, the electrical resistance does not increase even under low temperature and low humidity conditions, and therefore good image quality without blurring can be obtained.

The polymethylene ester resin is dispersed in an organic solvent solution such as toluene, xylene, methyl ethyl ketone, acetone, ethyl acetate, dichloroethane, chlorobenzene, etc., and applied to a conductive substrate by a method such as bar code, spin code, date coating, etc. An undercoat layer is formed.

The molecular weight of the polymethylene ester resin used in the present invention is 3.
It is preferably from 10,000 to 100,000. That is, if the molecular weight of the polymethylene ester resin is lower than 30,000, the coating strength of the undercoat layer decreases, and if the molecular weight exceeds 100,000, it becomes difficult to dissolve in an organic solvent solution, making it difficult to form a coating. . Further, the thickness of the undercoat layer is preferably 0.5 μm to 10 μm. That is, if the thickness is less than 0.65 μm, charge injection from the conductive substrate will not be blocked, and white spots will appear on the copy. On the other hand, if the thickness of the undercoat layer exceeds 10 μm, the residual potential will increase and cause burr.

The polymethylene ester resin itself can be used alone, but inorganic pigments such as tin oxide, titanium oxide, zinc oxide, and aluminum powder may be added for the purpose of a light-scattering subbing layer or a light-absorbing subbing layer. .

In a preferred embodiment of the present invention, a photosensitive layer having a functionally separated laminated structure in which a charge generation layer and a charge transfer layer are sequentially laminated is suitable as the photosensitive layer. The layer structure of the electrophotographic photoreceptor of the present invention using the photosensitive layer having the functionally separated laminated structure is shown in FIG. 1. The conductive substrate 1 is made of aluminum, nickel, brass,
Metal sheets or cylinders such as copper or stainless steel, plastic sheets with aluminum, chromium, palladium, metal oxides, etc. vacuum-deposited on them, conductive treated plastic plates or paper, and metal oxide sheets or cylinders. A cylinder etc. can be used.

As the charge generating material used in the charge generating layer 3, known organic or inorganic photoconductive pigments can be used. Among these pigments, disazo pigments, trisazo pigments,
Perylene pigments, quinacridone pigments, phthalocyanine pigments, or zinc oxide have excellent properties as charge generating materials.

The charge generating material is dispersed in a binder solution of a suitable adhesive such as polyvinyl butyral, polyester, polymethyl methacrylate, polystyrene, polycarbonate, etc., and identified by a bar code, spin code, dipco-1 method, etc. The charge generation layer 3 is formed by coating the undercoat layers 2-, , l- made of polymethylene ester resin.

On the other hand, the charge transfer material used in the charge transfer layer 4 is as follows:
Any known hole transfer material or electron transfer material can be used.

Among these, suitable sign transfer substances include polycyclic aromatic compounds such as an)-helix, pyrene, pyrene, and nanthrene in the main chain or side chain, or indole, carbazole, oxazole, imidazole, pyrazole, oxadiazole, Compounds having nitrogen-containing cyclic compounds such as triapool, or hydrazone compounds, such as poly-N
-vinylcarbazole, N-ethylcarbazole, 2
．． 5-diphenyl-1,3,4-oxadiazole, p
-diethylaminobenzaldehyde-(diphenylhydrazone) and the like. In addition, suitable electron transfer substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinone dimethane, 2°4.7-1-dinitro-9-fluorenone, 2.4.5.7 tetranitro-9-fluorenone, 214+54 Tetranitroxan[・n, 2.4.8- Trinidrothioxanthone, 2
．． 6.8-) Rinitro 4H-indeno (1,2-
b) Thiophen-4-one, 1,3,7-trinitrodibenzothiophene-5,5-dioxide, and the like.

These iKM transfer materials are generally low-molecular and have poor film-forming properties by themselves, so they are applied after being dissolved in a suitable binder solution.

Binders used with the charge transfer material include polycarbonate, polystyrene, polyvinyl chloride, polymer acrylate, polyvinyl acetate, silicone resin, vinyl chloride-vinyl acetate copolymer resin, epoxy resin, etc. Polycarbonate is particularly suitable. The coating thickness of the charge transport layer is 10 to 30 μm, preferably 15 to 25 μm.

Further, the photosensitive layer 17 is not limited to the above-mentioned photosensitive layer having a functionally separated laminate structure, but may be a single layer structure or a photosensitive layer having another functionally separated laminate structure. For example, a photosensitive layer containing well-known inorganic photoconductive substances such as zinc oxide and cadmium sulfide dispersed in a resin, a photosensitive layer using selenium, selenium-tellurium, etc., and amorphous silicon-based materials. Those using the photosensitive layer as the photosensitive layer can be used.

〔Example〕

Examples of the present invention will be described below, but these are merely illustrative, and the present invention is not limited to only these conditions.

Example 1 Polymethylene ester resin with a molecular weight of 80,000 (Plaxel H
, manufactured by Daicel Chemical Industries, Ltd.) was dissolved in 90 g of toluene to prepare a coating solution for the undercoat layer. The coating solution was applied to a conductive substrate, which was an aluminum-deposited polyester film having a thickness of 100 μm, to form an undercoat layer having a thickness of 5 μm after drying.

Next, (n) was dispersed for 5 hours using a dispersion device using a glass piece to obtain a coating solution for the charge generation layer. This solution was applied onto the undercoat layer, dried at 60° C. for 10 minutes, and then vacuum-dried at 20° C. for 3 hours to form a charge generation layer with a thickness of 0.5 μm.

Next, these were mixed and dissolved to obtain a coating solution for the charge transfer layer. This solution was applied to the top of the charge generation layer and dried in the same manner to form a charge transport layer having a thickness of 20 microns.

The electrophotographic properties of the electrophotographic photoreceptor of the present invention obtained as described above were measured using an electrostatic paper analyzer EPA 8100 manufactured by Kawaguchi Electric Co., Ltd. under the following conditions.

Table 1 Repeated measurement results The electrostatic paper analyzer measurement results show that the surface potential is -1240V and the half-life exposure sensitivity (E+z
z) was 1.241ux-see.

In addition, the electrostatic paper analyzer described above was used to repeatedly evaluate charging and exposure at 1o under the following conditions.
It was carried out ooo times. The results are shown in Table 1.

■o: Surface potential R: Potential retention rate after 2 seconds El/□: Half-reduced exposure sensitivity V8: Residual potential The electrophotographic photoreceptor according to Example 1 has a resistance of 1000 as shown in Table 1.
Even after repeated charging and exposure 0 times, there was no change in surface potential, dark decay, or sensitivity, and the residual potential did not increase. Also,
There was no peeling of the photosensitive layer.

Example 2 An undercoat layer coating solution, a charge generation layer coating solution, and a charge transfer layer coating solution similar to those in Example 1 were applied to an aluminum drum with a diameter of 60 mm as a conductive substrate by the same method. , an electrophotographic photoreceptor of the present invention was produced. The electrophotographic photoreceptor was set in a Xerox copier 2700,
A copy test was conducted on up to 20,000 sheets in an atmosphere of 23° C. and 55% RH.

As a result, a uniform image was obtained without pinholes on the photoreceptor. In this case, the image density and soil blurring results obtained using the Macbeth densitometer are shown in Table 2.
After copying 000 sheets, there was almost no difference.

Next, the above electrophotographic photoreceptor was copied using the above-mentioned copying machine in an atmosphere of 10° C. and 15% RH, but no ground force blur occurred and the photosensitive layer did not peel off.

Table 2 Image Properties Example 3 An undercoat layer was applied in the same manner as in Example 1 using a polymethylene ester resin (Plaxel I4, manufactured by Daicel Chemical Industries, Ltd.) having a molecular weight of 40,000.

Further, a charge generation layer and a charge transport layer were prepared in the same manner as in Example 1, except that the disazo pigment in Example 1 was changed to a bisazo pigment having the following structural formula, and the hydrazone compound was changed to a styryl compound having the following structural formula. An electrophotographic photoreceptor of the present invention was prepared by coating the above.

Next, the electrophotographic properties of the electrophotographic photoreceptor were measured in the same manner as in Example 1, and the surface potential was 1,980 square meters, and the half-life exposure sensitivity (El/2) was 1.52 lux = sec. In addition, when a copy test was conducted in the same manner as in Example 2, even in an atmosphere of 15° C. and 20% R1), a uniform image was obtained with no background blur or white spots, and the photosensitive layer did not peel off. .

Example 4 The thickness of the undercoat layer was 10. An electrophotographic photoreceptor of the present invention was produced in the same manner as in Example 3 except that cam was used. When the electrophotographic characteristics of the electrophotographic photoreceptor were measured in the same manner as in Example 1, the surface potential was -1420 V and the half-decrease exposure sensitivity (E+z,) was 1.731 ux-sec. Further, when a copy test was conducted in the same manner as in Example 2, the photosensitive layer did not peel off and no white spots were observed on the copies.

Comparative Example Polyamide (nylon CMsoo) was used as the resin for the undercoat layer.
An undercoat layer having a thickness of 3 μm was coated using the same method as in Example 1, using the same method as in Example 1. The same charge generation layer and charge transfer layer as in Example 3 were coated on the undercoat layer to prepare a comparative photoreceptor. When the electrophotographic characteristics of the photoreceptor were measured in the same manner as in Example 1, the initial half-reduced exposure sensitivity (E1
7t) is 1.861ux-see and the residual potential (Vl)
was 50V.

After repeating charging and exposure 2000 times, the half-reduced exposure sensitivity (E17□) was 3.49 1ux・sec %
The residual potential (Vl) changed to 145 ■. In addition, when a copy test was conducted in the same manner as in Example 2, copies with severe ground braking were obtained.

〔Effect of the invention〕

In the present invention, by using a specific polymethylene ester resin as an undercoat layer, the residual potential does not increase even after repeated use, the sensitivity does not change, and uniform copies without fog can be obtained even under low temperature and low humidity. Furthermore, an electrophotographic photoreceptor can be obtained which does not cause white spots on copies, has excellent environmental stability, and has improved adhesiveness between the conductive substrate and the photosensitive layer.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a preferred layer structure of the electrophotographic photoreceptor of the present invention. DESCRIPTION OF SYMBOLS 1... Conductive substrate, 2... Subbing layer, 3... Charge generation layer, 4... Charge transfer layer, 5... Photosensitive layer. Written amendment 1999 Director General of the Japan Patent Office Yoshi 1) Takeshi Moon 1, Indication of the case 1999 Patent Application No. 15032 2, Name of the invention Electrophotographic photoreceptor 3, Person making the amendment March 15th 7, Amendment Contents (1) "Made by Tijin Co., Ltd." in the second line from the top and bottom of Structural Formula (III) on page 10 of the specification is corrected to "Made by Idemitsu Petrochemical Co., Ltd." 4゜5゜6゜Date of amendment order No number of inventions increased due to voluntary amendment amendment ``Detailed description of invention'' column of specification subject to amendment

Claims (3)

[Claims] (1) An electrophotographic photoreceptor comprising an undercoat layer and a photosensitive layer sequentially laminated on a conductive substrate, characterized in that the undercoat layer is made of a polymethylene ester resin represented by the following general formula (I). Electrophotographic photoreceptor. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (2) The molecular weight of the polymethylene ester resin is 30,000~
2. The electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photoreceptor has a weight of 100,000. (3) The electrophotographic photoreceptor according to claim 1, wherein the undercoat layer has a coating thickness of 0.5 μm to 10 μm.