JPH05158251A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body having high sensitivity, high durability and reliability and preventing the rise of residual potential even after repeated use over a long period of time. CONSTITUTION:An electric charge transferring layer is formed on an electric charge generating layer contg. butyral resin or bisphenol A type polycarbonate resin as binding resin with a coating soln. contg. a solvent which does not practically dissolve the electric charge generating layer. When polycarbonate resin represented by the formula is contained as binding resin in the electric charge transferring layer, a more significant effect is produced. In the formula, each of X and X<1> is H, halogen or methyl and R is H, halogen, hydroxyl, carboxyl, acetyl or 1-5C alkyl.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copying machine, a printer,
The present invention relates to an electrophotographic photosensitive member used in a device such as a facsimile.

[0002]

2. Description of the Related Art Conventionally, in a laminated type photoreceptor having a charge generation layer and a charge transport layer provided on a conductive substrate, the charge transport layer is represented by the following structural formula (II) as a binder resin. Polycarbonate resin consisting of repeating units is used.

[Chemical 1] Further, the charge transport layer is generally tetrahydrofuran,
It is formed on the charge generation layer using an organic solvent such as methylene chloride. In the laminated photoconductor thus manufactured, the residual potential is increased by repeating charging and exposure for a long time.

Therefore, when a polycarbonate resin comprising a repeating unit represented by the structural formula (I) is used as the binder resin, the residual potential does not rise at room temperature and normal humidity (22 ° C. 40% RH), but the high temperature is high. There is still a problem that the residual potential rises under humidity (30 ℃ 90% RH).

[Chemical 2] (In the formulas, X and X ¹ represent a hydrogen atom, a halogen atom, or a methyl group, and R represents a hydrogen atom, a halogen atom, a hydroxyl group, a carboxyl group, an acetyl group, or an alkyl group having 1 to 5 carbon atoms.)

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photosensitive member which is improved in the above-mentioned drawbacks and which does not raise the residual potential even after repeated use over a long period of time, and which has high sensitivity, high durability and high reliability. That is.

[0005]

In a laminated type photoreceptor having a charge generation layer and a charge transport layer provided on a conductive substrate, the binder resin of the charge generation layer is butyral resin or bisphenol A type polycarbonate. The object is achieved by forming a charge transport layer on the charge generation layer by using a charge transport layer coating liquid which is composed of a resin and which does not substantially dissolve the charge generation layer. Further, the effect is further promoted when the charge transport layer contains a polycarbonate resin composed of the repeating unit represented by the structural formula (I) as a binder resin.

The present inventors have found that when the binder resin of the charge generating layer is composed of butyral resin, bisphenol A type polycarbonate resin, etc., organic charge of methylene chloride, ethylene chloride, tetrahydrofuran or the like is formed on the charge generating layer. When the charge transport layer is formed by using a medium, the binder resin of the charge generation layer is dissolved in these organic solvents, so that the interface between the charge generation layer and the charge transport layer mixes and affects the electrostatic characteristics. I found a thing. That is, by using an organic solvent of the charge transport layer that is insoluble in the binder resin of the charge generation layer, a sharp interface is formed without the interfaces of the charge generation layer and the charge transport layer being mixed with each other. Even under high temperature and high humidity, the residual potential does not increase, and a highly durable and highly reliable photoreceptor can be obtained.

According to the present invention, a charge transport layer coating liquid comprising an organic solvent agent which does not substantially dissolve the charge generation layer is formed on the charge generation layer containing butyral resin or bisphenol A type polycarbonate resin as a binder resin. Although the charge transport layer is provided, the organic solvent agent is preferably toluene, dioxane, xylene, benzene, or a mixture of two or more of these organic solvent agents.

[0008]

【Example】

Example 1 An electrophotographic photoreceptor of the present invention was prepared by providing a photosensitive layer as described below on a conductive base material obtained by forming an Al layer having a thickness of 500 Å on a polyethylene terephthalate film having a thickness of 75 μm by a vacuum deposition method. Trisazo pigment (Compound 1) (manufactured by Ricoh) 15 g Butyral resin (KYHL: manufactured by UCC) 5 g Cyclohexanone (manufactured by Kanto Chemical Co., Ltd.) A mixture of 150 g was used for 48 hours using a glass pot and an agate ball of 10 mmφ. After ball milling, 300 g of cyclohexanone was added and milling was performed for another hour. Cyclohexanone was further added to this milling solution to prepare a charge generation layer application liquid having a solid content concentration of 2 wt%, and a charge generation layer having a thickness of 0.2 μm was provided.

[Chemical 3] Then, a charge transport layer coating solution having the following composition was applied onto this charge generation layer by a nozzle coating method, and dried at 130 ° C. for 15 minutes to form a charge transport layer having a thickness of 20 μm to form a photosensitive layer. .. Charge transport material (compound 2) (manufactured by Ricoh) 9g Polycarbonate (resin 1) (TS2050: manufactured by Teijin Chemicals) 10g Toluene 90g

[Chemical 4]

[Chemical 5]

Example 2 Except that toluene was changed to dioxane in Example 1,
An electrophotographic photosensitive member was produced in the same manner as in Example 1.

Example 3 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that benzene was used instead of toluene.

Example 4 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that xylene was used instead of toluene.

Comparative Example 1 Polycarbonate resin 1 in Example 1 was replaced with a structural formula (I
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the bisphenol A type polycarbonate (resin) represented by I) (C-1400 manufactured by Teijin Chemicals Ltd.) was used.

Comparative Example 2 An electrophotographic photosensitive member for comparison was prepared in the same manner as in Example 1 except that tetrahydrofuran was used instead of toluene.

Comparative Example 3 An electrophotographic photosensitive member was produced in the same manner as in Comparative Example 1 except that tetrahydrofuran was used instead of toluene in Comparative Example 1.

The photoconductor thus manufactured was measured by a dynamic method using an electrostatic characteristic measuring device SP-428 (manufactured by Kawaguchi Denki Seisakusho). First, it was charged with an applied voltage of -6 KV for 20 seconds, then dark-decayed for 20 seconds, and further exposed with a tungsten lamp for 30 seconds so that the illuminance on the surface of the photoreceptor was 4.5 lux. After exposure, the surface potential is -800V → -80V after exposure.
Exposure dose E1 / 10 (lux.sec) required to obtain
Was evaluated by measuring the surface potential after 30 seconds of exposure. The sensitivity and residual potential were also measured after a forced fatigue test (while the photoreceptor was rotated at 1000 rpm, corona charging and exposure with a tungsten lamp were repeated until the photoreceptor surface was -800 V and 9.6 μA). .. The results are shown in Table 1 below.

[0016]

[Table 1]

On the other hand, the photoconductor of Example 1 was mounted on a modified electrophotographic laser beam printer (RICOH LP2310-SP5) and subjected to an image output test. A clear image was obtained. Comparative Example 2.3
When the image output test was performed on the photoconductor of
Dirt on the background became visible from around 35,000 and 20,000 sheets, respectively.

A transmission electron microscope (Hitachi H-500H)
When the cross sections of the photoconductors of Example 1 and Comparative Example 2 were observed, the interface between the charge generation layer and the charge transport layer was clear in the photoconductor of Example 1, whereas the interface in Comparative Example 2 was clear. It was not clear, and it seemed that both layers were mixed.

[0019]

The binder resin of the charge generating layer is a butyral resin or a solvent which does not substantially dissolve the charge generating layer on the charge generating layer composed of a bisphenol A type polycarbonate resin. A charge transporting layer coating solution is used to form a charge transporting layer, and a polycarbonate resin comprising a repeating unit represented by the structural formula (I) as a binder resin for the charge transporting layer. By containing, the residual potential does not rise even after repeated use for a long time, a good image without image defects can be obtained, and a highly sensitive, highly durable and highly reliable electrophotographic photoreceptor can be obtained.

Claims (2)

[Claims] 1. A laminate-type photoreceptor having a charge generation layer and a charge transport layer provided on a conductive substrate, wherein the binder resin of the charge generation layer is made of butyral resin or bisphenol A type polycarbonate resin. An electrophotographic photoreceptor comprising a charge transport layer formed on the charge generation layer by using a charge transport layer coating liquid comprising a solvent that does not substantially dissolve the charge generation layer. 2. The electrophotographic photosensitive member according to claim 1, wherein the charge transport layer contains, as a binder resin, a polycarbonate resin including a repeating unit represented by the following structural formula (I). (In the formula, X and X ¹ represent a hydrogen atom, a halogen atom, or a methyl group, and R represents a hydrogen atom, a halogen atom,
Hydroxyl group, carboxyl group, acetyl group, or carbon number 1
~ Represents an alkyl group of 5)