JPH03134670A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To eliminate the influence of residual stresses and to obtain the photosensitive body having good characteristics by constituting the photosensitive body of a conductive layer, a charge generating layer and a charge transfer layer and adding a specific low-mol. org. compd. to the charge transfer layer. CONSTITUTION:The charge transfer layer contain an org. charge transfer material and a binder resin. The hole transfer type charge transfer material is a hydrazone compd., enamine compd., etc., and the electron transfer type charge transfer material is an arom. nitro compd., diphenoquinone deriv., etc. The binder resin is advantangeous in terms of the compability of a thermoplastic resin contg. a benzene ring with the charge transfer material. One or plural of biphenyl, oterpheny, m-terphenyl, diphenyl, diphenyl carbonate, phenyl benzoate, and diphenyl pthalate are used in combination as a residual stress lowering agent. The resin and antioxidant, etc., are dissolved in a solven in the prescribed compsn. with the charge transfer material and the soln. is applied on the photosensitive body. The charge generating layer is a coated film formed by dispersing an azo pigment, phthalocyanine, etc., into a polyamidersin, etc., and the conductive layer is Al, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor using an organic photoconductor.

[Prior Art] Selenium, cadmium sulfide, zinc oxide, etc. have long been known as photoconductors used in electrophotographic processes such as copying machines and optical printers. In recent years, organic electrophotographic photoreceptors using organic photoconductors have come into widespread use, as they have the advantages of being lightweight, highly flexible, low-toxic, and highly transparent. It has become to.

The basic characteristics required of an electrophotographic photoreceptor include good charge acceptance and charge retention in the dark, high sensitivity, low residual potential, and spectral sensitivity appropriate to the intended use. , excellent durability, and good workability. However, among the conventionally proposed organic photoconductors, there are hardly any that satisfy all of these required characteristics using a single material.

Therefore, a so-called function in which a conductive layer is laminated with a layer containing a charge-generating substance that absorbs light and generates charges, that is, a charge-generating layer, and a layer containing a charge-transfer substance that moves the generated charges, that is, a charge-generating layer. Separately laminated photoreceptors are currently mainly used. This is aimed at improving the characteristics and widening the range of material selection by assigning the two functions of the photoreceptor to different materials.

[Problems to be Solved by the Invention] The charge transfer layer in a functionally separated layered photoreceptor is usually manufactured by coating a paint containing a charge generating substance and a binding resin dissolved in an organic solvent and drying it by heating. There was a problem in that residual stress was generated in the charge transfer layer coating, causing curling and peeling of the photoreceptor. However, when commercially available plasticizers such as phthalic acid alkyl esters were added to reduce residual stress, a problem arose in that the electrophotographic properties were impaired. In order to solve this problem, the present inventors conducted exploratory research on additives that reduce residual stress and do not impair electrophotographic properties, and found that a specific low-molecular organic compound (residual stress reducer) They discovered that it has the desired properties and arrived at the present invention.

An object of the present invention is to provide an electrophotographic photoreceptor that is free from problems caused by residual stress in the charge transfer layer and has good electrophotographic properties by adding a specific low-molecular-weight organic compound to the charge transfer layer.

[Means for Solving the Problems] The electrophotographic photoreceptor of the present invention is composed of a conductive layer, a charge generation layer, and a charge transfer layer, the charge transfer layer containing an organic charge transfer substance and a binding resin, And it is characterized by containing at least one compound selected from biphenyl, 0-terphenyl, m-terphenyl, diphenyl ether, diphenyl carbonate, phenyl benzoate, and diphenyl phthalate.

Regarding the stacking order of the conductive layer, charge generation layer, and charge transfer layer, the following two configurations are possible.

(1) Conductive layer/charge generation layer/charge transfer layer (2) Conductive layer/
Charge Transfer Layer/Charge Generation Layer Since commonly used charge transfer substances are of the hole transfer type, when used in a Carlson electrophotographic process, the photoreceptor of configuration (1) is negatively charged;
The photoreceptor of configuration (2) is positively charged and used.

When an electron transfer type material is used as the charge transfer material, the relationship between the structure and the charging method is the opposite of the above. Each layer constituting the photoreceptor will be described in detail below.

The charge transfer layer contains (A) an organic charge transfer substance, (B) a binding resin, (C) a residual stress reducing agent, and (D) other additives added as necessary. Each component described below is used.

As the charge transfer substance (A), any known charge transfer substance can be used. There are known charge transfer materials of hole transfer type and electron transfer type, and it is possible to use either of them. . Examples of hole-transfer type charge transfer substances include (a) hydrazone compounds (b) enamine compounds (C) oxadiazole derivatives (d) pyrazoline derivatives (e) oxazole derivatives (f) carbazole derivatives (g) aromatic amines Derivatives (h) stilbene derivatives (i) 4 arylbutadiene derivatives (D arylhexatriene derivatives (k) organic polysilane derivatives, etc. Examples of electron transfer charge transfer substances include (1) aromatic nitro compounds (m) Diphenoquinone derivatives may be mentioned, but the charge transfer substance used in the present invention is not limited thereto.

Any known binder resin can be used as the binder resin (B), but a thermoplastic resin containing a benzene ring in its structure is preferably used from the viewpoint of compatibility with the charge transfer substance.

As the residual stress reducing agent (C), at least one compound selected from biphenyl, 0-terphenyl, m-terphenyl, diphenyl ether, diphenyl carbonate, phenyl benzoate, and diphenyl phthalate is used, but these compounds may be used alone. may be used, or a plurality of compounds may be used in combination. These compounds have the property of reducing the residual stress of the coating film without impairing the electrophotographic properties.

As other additives (D), antioxidants, ultraviolet absorbers, leveling agents, lubricants, etc. can be added, but these are not necessarily added.

The charge transfer layer is formed by dissolving each of the above-mentioned components in an appropriate solvent, applying a coating, and drying the coating.

The preferable composition ratio of the charge transfer layer is as follows based on the charge transfer substance. Note that the composition ratio is expressed as a weight ratio.

Binding resin/charge transfer substance = 50/100 to 150/100 Residual stress reducing agent/charge transfer substance = 5/100 to 50/100 Other additives/charge transfer substance = O/100 to 20/100 Charge generation The layer contains a charge generating substance as an essential component. As the charge generating substance used here, any known charge generating substance can be used. Examples include, but are not limited to, the following:

(a) Azo pigments (b) Perylene pigments (c) Phthalocyanine derivatives (d) Squarylium dyes (e) Pyrylium and thiopyrylium derivatives (f) Aromatic polycyclic quinone compounds (g) Pyrrolopyrrole derivatives These charge generating substances are: For the purpose of adjusting the spectral characteristics or stabilizing the characteristics, a plurality of them can be used in combination.

The charge generation layer can be formed by applying a paint in which a charge generation substance is dispersed in a solvent, a paint in which a charge generation substance and a suitable binding resin are dispersed in a solvent, or by vapor deposition of a charge generation substance. formed by. If the coating amount or adhesion amount of the charge generation layer is too large, the chargeability and repetition stability will be lowered, and if it is too small, the sensitivity will be lowered.

The preferred coating amount or adhesion amount of the charge generation layer is 0.01 to 0.01.
It is 1g/am2.

When the charge generation layer is composed of a charge generation substance and a binding resin, a known binding resin can be used as the binding resin. Preferably used binding resins include the following.

Polyamide, polyester, polyurethane, polyimide, polycarbonate, polyarylate, polyacetal, polyethylene oxide, polypropylene oxide, polymethacrylate, polyacrylate, polystyrene, polyvinyl acetate, polyvinyl chloride, alkyd resin, butyral resin, silicone resin, Examples include, but are not limited to, epoxy resins and urea resins. These binding resins may be used alone or in a mixed system of two or more types, or may be a copolymer.

Further, crosslinking may be carried out by adding a suitable crosslinking agent.

When using a binding resin, the weight ratio of the charge generating substance to the binding resin is 110 from the viewpoint of film strength, adhesion and sensitivity.
．． It is preferable to set it to 2 to 1/2.

Any known conductive layer can be used. For example, a metal material processed into a predetermined shape is used.

Examples of metal materials in this case include aluminum, stainless steel, copper, nickel, and the like. Also,
A thin film of a conductive material formed on a suitable support may also be used.

In this case, examples of the support include glass, resin, metal, paper, cloth, etc., and examples of the conductive material include metals such as aluminum, palladium, rhodium, gold, and platinum, carbon, and tin oxide. , indium tin oxide, polymer electrolytes, and conductive polymers, and examples of forming methods include vapor deposition, sputtering, coating, lamination, plating, and the like. The shape of the conductive layer can be freely selected from flat plates, drums, films, endless belts, etc. depending on the purpose of use.

An appropriate undercoat layer can be provided on the conductive layer to improve adhesion and control charge injection.

Further, a surface protective layer can be provided on the surface of the photoreceptor for the purpose of improving durability.

[Example] The present invention will be specifically explained below using examples.

[Experiment method] (1) Preparation of photoreceptor 1.75 parts of titanyl phthalocyanine and polyvinyl butyral resin "S-LEC" BL-1 (manufactured by Tanesui Kagaku ■) 1.
A coating liquid was prepared by dispersing 75 parts of cyclohexanone in 5 parts of 96° of cyclohexanone, and the solid content was applied to an aluminum-deposited polyester film "Metal Me"#75 (manufactured by Toshi ■) using a metering bar at a solid content of 0.5 g/ Apply to m2 and 80
A charge generation layer was formed by drying at .degree. C. for 20 minutes.

A charge transfer layer paint was applied thereto using a metering bar and dried at 80° C. for 20 minutes to form a charge transfer layer with a thickness of 20 μm, thereby preparing a photoreceptor sample having the photosensitive layer of Structure 1.

(2) Evaluation of residual stress The prepared photoreceptor sample was cut into a square of 50 mm x 50 mm, placed on a flat surface, and the amount of curl, that is, the height of the warped end portion was measured. Since the larger the residual stress in the charge transfer layer, the larger the amount of curl, this was used to evaluate the magnitude of the residual stress.

(3) Evaluation of electrophotographic properties Electrophotographic properties of photoreceptor samples were measured under the following conditions. Using an electrostatic copying paper tester EPA-8100 (manufactured by Kawaguchi Electric), mode 5TAT-1, corona voltage -5
After being charged at kV and dark decaying for 1 second, it was irradiated with monochromatic light of 800 nm for 5 seconds at an exposure intensity of 1 μW/cm 2 , and the half-reduction exposure and residual potential were determined from the potential decay curve.

Comparative Example 1 10 parts of charge transfer substance of the following formula and polyarylate resin U-1
A photoreceptor sample was prepared using a paint prepared by dissolving 10 parts of 00 (manufactured by Unitika) in 80 parts of 1,2-dichloroethane as a charge transfer station paint.

The amount of curl and the electrophotographic properties were as follows.

Curl amount 9 mm Half-decrease exposure amount 0.48 pJ/cm2 Residual potential Ov Comparative example 2 10 parts of the charge transfer substance used in Comparative example 1, 7 parts of polyarylate resin U-100, and 3 parts of commercially available plasticizer dioctyl phthalate were mixed with 1,2-dichloroethane. A photoreceptor sample was prepared using a paint dissolved in 80 parts as a charge transfer station paint. The amount of curl and the electrophotographic properties were as follows.

Curl amount: 1 mm Half-decrease exposure amount: 0.64 μJ/Cm2 Residual potential -7V Although the amount of curl was reduced by adding dioctyl phthalate, a significant decrease in sensitivity and increase in residual potential were observed, impairing the electrophotographic properties.

Example 1 A photoreceptor sample was prepared using a paint prepared by dissolving 10 parts of the charge transfer substance used in Comparative Example 1, 7 parts of polyarylate resin U-100, and 3 parts of biphenyl in 80 parts of 1,2-dichloroethane as a charge transfer layer paint. Created. The amount of curl and the electrophotographic properties were as follows.

Curl amount 1 mm Half-decrease exposure amount 0.51 μJ/Cm2 Residual potential 0 ■ Example 2 10 parts of the charge transfer substance used in Comparative Example 1, polyarylate resin U-1007 parts, and 0-terphenyl 3 parts were mixed in 1,2-
A photoreceptor sample was prepared using a paint dissolved in 80 parts of dichloroethane as a charge transfer layer paint. The amount of curl and the electrophotographic properties were as follows.

Curl amount 1 mm Half-decreased exposure amount 0.52 μJ/Cm2 Residual potential Ov Example 3 10 parts of the charge transfer substance used in Comparative Example 1, 7 parts of polyarylate resin U-100, and 3 parts of m-terphenyl were mixed into 1,2-
A photoreceptor sample was prepared using a paint dissolved in 80 parts of dichloroethane as a charge transfer layer paint. The amount of curl and the electrophotographic properties were as follows.

Curl amount 1 mm Half-decrease exposure amount 0.48 μJ/cm2 Residual potential QV Example 4 10 parts of the charge transfer substance used in Comparative Example 1, 7 parts of polyarylate resin U-100, and 3 parts of diphenyl ether were mixed in 1.2 parts
- A photoreceptor sample was prepared using a paint dissolved in 80 parts of dichloroethane as a charge transfer layer paint. The amount of curl and the electrophotographic properties were as follows.

Curl amount 1 mm Half-decrease exposure amount 0.52 μJ/cm2 Residual potential Ov Example 5 10 parts of the charge transfer substance used in Comparative Example 1, 7 parts of polyarylate resin U-100, and 3 parts of diphenyl carbonate were mixed in 1,2-
A photoreceptor sample was prepared using a paint dissolved in 80 parts of dichloroethane as a charge transfer layer paint. The amount of curl and the electrophotographic properties were as follows.

Curl amount 1 mm Half-decrease exposure amount 0.53 uJ/cm2 Residual potential Ov Example 6 10 parts of the charge transfer substance used in Comparative Example 1, 7 parts of polyarylate resin U-100, and 3 parts of phenyl benzoate were mixed in 1,2-
A photoreceptor sample was prepared using a paint dissolved in 80 parts of dichloroethane as a charge transfer layer paint. The amount of curl and the electrophotographic properties were as follows.

Curl amount 1 mm Half-decreased exposure amount 0.53 μJ/cm2 Residual potential Ov Example 7 10 parts of the charge transfer substance used in Comparative Example 1, 7 parts of polyarylate resin U-100, and 3 parts of diphenyl phthalate were mixed into 1.2 parts of
- A photoreceptor sample was prepared using a paint dissolved in 80 parts of dichloroethane as a charge transfer layer paint. The amount of curl and the electrophotographic properties were as follows.

Curl amount halved, exposure amount residual potential [Effects of the invention] By adding a specific low-molecular organic compound to the charge transfer layer, there are no problems such as curling or peeling due to residual stress in the charge transfer layer, and the electrophotographic properties are good. An electrophotographic photoreceptor can be obtained.

mm O, 47μJ/cm2 Ov

Claims (1)

[Claims] Consisting of a conductive layer, a charge generation layer and a charge transfer layer,
The charge transfer layer contains an organic charge transfer substance and a binding resin, and at least one compound selected from biphenyl, o-terphenyl, m-terphenyl, diphenyl ether, diphenyl carbonate, phenyl benzoate, and diphenyl phthalate. An electrophotographic photoreceptor characterized by containing.