JPS581772B2 - electrophotographic photoreceptor - Google Patents

Description

[Detailed description of the invention] The present invention relates to an electrophotographic photoreceptor.

Electrophotographic photoreceptors have various configurations in order to obtain predetermined characteristics or depending on the type of electrophotographic process to which they are applied.

As representative electrophotographic photoreceptors, there are photoreceptors having a photoconductive layer formed on a support and photoreceptors having an insulating layer on the surface, which are widely used.

The photoreceptor, which is composed of a support and a photoconductive layer, is used for image formation by the most common electrophotographic processes, ie, charging, image exposure and development, and optionally transfer.

Also, for photoreceptors with an insulating layer, this insulating layer can protect the photoconductive layer, improve the mechanical strength of the photoreceptor, improve dark decay characteristics, or be applied to certain electrophotographic processes (and even It is established for the purpose of eliminating pollution).

Representative examples of photoreceptors having such insulating layers or electrophotographic processes using photoreceptors having insulating layers are, for example, U.S. Pat.
JP 16429, JP 38-15446, JP 46-3713, JP 42-23910, JP 43-24748, JP JP 1977-1
It is described in Japanese Patent Publication No. 9747, Japanese Patent Publication No. 36-4121, etc.

As a matter of course, electrophotographic photoreceptors are required to have predetermined sensitivity electrical characteristics and optical characteristics depending on the electrophotographic process to which they are applied.

Among these, electrical adhesion between the photoconductive layer and the support is also one of the important properties.

In order to form an electrostatic image by subjecting an electrophotographic photoreceptor to a predetermined electrophotographic process, the charges on the photoconductive layer are erased by selectively becoming electrically conductive with the support in the exposed area, or It is necessary to inject charges between the insulating layer and the photoconductive layer from the support side.

In order to make these conductive states or charge injection more complete, it is necessary to have good electrical adhesion between the photoconductive layer and the support in order to form a high-contrast electrostatic image.

In particular, when the photoconductive layer is mainly composed of a photoconductor and a binder, both the photoconductor and the binder are in contact with the surface of the support at the interface between the photoconductive layer and the support.

Further, since a relatively large amount of photoconductor is dispersed and contained, there are many minute voids in the photoconductive layer, and there are portions where such voids are in contact with the surface of the support.

Since the binder and the photoconductor have different resistances, and since the binder is a non-photoconductive material, the resistance of the binder and the photoconductor upon exposure becomes even more different.

Furthermore, since the voids are also considered to have high resistance, the electrical adhesion between the photoconductive layer and the support is not uniform depending on the location.

This causes non-uniformity in the conduction state of the photoconductive layer during exposure or in the injection of charge from the support into the photoconductive layer, causing roughness and a decrease in contrast in the formed image.

The main object of the present invention is to provide an electrophotographic photoreceptor in which the electrical adhesion between the support and the photoconductive layer is improved.

The present invention relates to an electrophotographic photoreceptor having a conductive support or a support whose surface is conductively treated, a photoconductive layer containing a photoconductor in a binder, and an insulating layer. A photoreceptor with a thin layer of conductive polymer between the layers.

One layer of conductive polymer is in close contact with the support and is also in close contact with the photoconductive layer.

Conductive polymers can also form a virtually continuous layer with the binder of the photoconductive layer, facilitating charge transfer between the photoconductive layer and the support and improving electrophotographic properties. be.

Furthermore, the properties of the photoconductive layer itself are not impaired.

The most common method of manufacturing photoreceptors is to coat a conductive polymer on a support, and then form a photoconductive layer and an insulating layer on the substrate.

Supports include stainless steel, Al, Cr, Mo, Au.
, In, Nb, Ta, V, Ti, Pt, Pd, etc., or alloys thereof; in the case of insulating supports, for example glass, In2O3, Sn
02, etc., or if it is a synthetic resin film such as polyimide film, Al, Ag, P
b, Zn, Ni, Au, Cr, Mo, Ir, Nb, Ta
, V, Ti, Pt, etc., by vacuum evaporation, electron beam evaporation, sputtering, etc., or by laminating with the metal, and the surface thereof is subjected to conductive treatment.

The shape of the support may be any shape, such as a cylinder, a belt, or a plate, and the shape may be determined as desired, or in the case of continuous high-speed copying, it may be an endless belt or a cylinder. is desirable.

The thickness of the support can be determined as appropriate, but if flexibility is required, it should be made as thin as possible as long as it can function as a support.

However, in such a case, the thickness is usually 10 μm or more in view of manufacturing and handling of the support, mechanical strength, etc.

As a conductive polymer, 103Ω-cm to 1010Ω
-cm, particularly in the range of 104 Ω-cm to 107.

Typical conductive polymers used in the present invention include polymers with a quaternary ammonium salt structure, polystyrene sulfonates, ammonium polyacrylates, tetracyanoquinodimethane complexes of polycationic polymers, and sulfonium nitrophene complexes. It is a nolate complex.

The thickness of a single layer of conductive polymer is set appropriately, but is usually 0.
．． It is preferable to set the thickness to 0.05 to 5μ, particularly 0.5 to 3μ.

The photoconductive layer is formed by dispersing a photoconductor in a binder.

As the binder used for forming the photoconductivity, various ordinary insulating resins can be used as appropriate.

For example, polyethylene, polyester, polypropylene,
polystyrene, polyvinyl chloride, polyvinyl acetate,
These include acrylic resin, polycarbonate, silicone resin, fluorine resin, and epoxy resin.

In addition, when using low resistance due to carbonization of resin,
Resins such as vinyl chloride-vinylidene acetate copolymer, polyvinyl butyral, vinyl chloride-vinylidene chloride copolymer, acrylic resin, and polystyrene-butylene copolymer are suitable.

Inorganic photoconductors include Zn, Hg, ACSb,
These include oxides, sulfides, iodides, and selenides of metals such as Bi, Cd, and Mo.

For example, zinc oxide, selenium, cadmium sulfide, zinc sulfide,
Cadmium selenide, lead oxide, arsenic sulfide, titanium oxide,
Examples include zinc titanium oxide, zinc silicon oxide, zinc magnesium oxide, mercury iodide, mercury oxide, valued mercury, indium sulfide, and calcium strontium oxide.

Examples of organic photoconductors include vinyl rubazole, anthracenephthalocyanine, trinitrofluorenone, polyvinyl rubazole, polyvinyl anthracene, and polyvinylpyrene.

The content of the binder forming the photoconductive layer is 100% of the photoconductor.
It is preferably 0.5 to 50 parts by weight, particularly 5 to 20 parts by weight.

Although the thickness of the photoconductive layer depends on the type and characteristics of the photoconductive layer used, it is generally preferred to have a thickness of about 5 to 100 microns, particularly about 10 to 50 microns.

The electrical resistance of the photoconductive layer in the dark is usually 1012 to 1
It is set in the range of 0.014 Ω·cm.

When forming a photoconductive layer on a single layer of conductive polymer, the photoconductive layer-forming paint is applied so that the photoconductive layer and the conductive polymer layer are as continuous as possible. It is particularly effective to cause the surface of the conductive polymer layer to swell, or to form a photoconductive layer when the conductive polymer layer has not been sufficiently dried after forming a coating film.

As the resin used for forming the insulating layer, various ordinary resins can be used as appropriate.

Examples include polyethylene, polyester, polypropylene, polystyrene, polyvinyl chloride, polyvinyl acetate, acrylic resin, polycarbonate, silicone resin, fluororesin, and epoxy resin.

Usually the thickness of the insulating layer is 0.1 to 100μ, especially 0.1
~50μ.

It is also effective to manufacture the photoreceptor by forming a photoconductive layer on an insulating layer, and further forming a conductive polymer layer and a support thereon, if necessary.

In this case, since a single layer of conductive polymer is formed on the photoconductive layer, the unevenness of the surface of the photoconductive layer is smoothed by the conductive polymer, and the adhesion between the photoconductive layer and the single layer of conductive polymer is improved. becomes good.

When the photoreceptor of the present invention is used in a method that uses charge injection from the support side during charging to move the charge between the insulating layer and the photoconductive layer, the photoconductive layer has a uniform charge. Particularly good for smooth injection.

A typical example of this type of system is the
As disclosed in Japanese Patent Publication No. 23910, Japanese Patent Publication No. 43-24748, etc., primary charging, secondary charging with the opposite polarity to the primary charging, AC snow removal, simultaneous image exposure and full surface exposure (if necessary) Full-surface exposure may be omitted.

) to form an electrostatic image;
As disclosed in Japanese Patent Publication No. 19748, Japanese Patent Publication No. 44-13437, and Japanese Patent Publication No. 49-44902, there are methods in which image exposure is carried out before or after secondary charging or AC static elimination, and other methods. As a method of
Examples include those disclosed in US Pat. No. 3,041,167.

In such an electrostatic image forming method that utilizes charge injection from a support, the ease with which charge can be injected from the support has a significant effect on the contrast of the formed electrostatic image. A photoreceptor of 1 is particularly effective.

Example 1 Sulfonate-based conductive polymer (product name: Oligo Z,
(manufactured by Tomoekawa Paper Mills) in ethyl alcohol was applied onto a 50 μm thick Al sheet and dried at room temperature for about 5 minutes to form a single layer of conductive polymer 0.5 μm thick.

Next, 100 parts by weight of CdS powder, binder resin vinyl chloride
A mixture of 10 parts by weight of vinyl acetate copolymer and butyl acetate as a solvent was coated on one layer of conductive polymer.
It was dried by heating at 0° C. for 30 minutes to form a photoconductive layer with a thickness of 40 μm.

Next, a 25 μm thick polyester film was adhered onto the photoconductive layer using an acrylic adhesive (trade name: DB9AO4, manufactured by Diabond Industries) to produce a photoreceptor.

Example 2 A solution of a conductive polymer (trade name: Elecondo PQ-50B, manufactured by Soken Chemical Co., Ltd.) dissolved in isobrobyl alcohol was applied onto an AA cylinder by dipping, and dried at 70°C for 5 minutes to form a 1μ thick conductive layer. A single layer of polymer was formed.

Next, a mixture of 100 parts by weight of CdS, 15 parts by weight of vinyl chloride-vinyl acetate copolymer as a binder, and methyl isobutyl ketone as a solvent was coated on top of it, and 90 parts by weight of CdS was applied.
A photoconductive layer having a thickness of 50 .mu.m was formed by heating and drying at .degree. C. for 10 minutes.

Furthermore, a methyl ethyl ketone solution of a photocurable polyurethane resin was applied thereon, dried, and then irradiated with ultraviolet rays to form an insulating layer with a thickness of 30 μm to produce a photoreceptor.

Example 3 In Example 1, a photoreceptor was manufactured using polyvinylbenzyltrimethylammonium salt (trade name: ECR-34, manufactured by Dow Chemical) instead of the sulfonate-based conductive polymer as the conductive polymer.

Example 4 A photoreceptor was manufactured using a cationic conductive polymer (trade name: Chemistat 6010, manufactured by Sanyo Chemical Industries, Ltd.) instead of the sulfonate conductive polymer as the conductive polymer in Example 1.

+2000V using each photoreceptor manufactured in Examples 1 to 4
An electrostatic image was formed by performing primary charging, AC static elimination, simultaneous image exposure (however, the original was a solid black sheet with an optical density of 1.2), and full-surface exposure (501 ux.sec).

This is developed with negatively charged wet toner, transferred to transfer paper by corona transfer, and heated and fixed to reproduce the copied image (black).
I got it.

In order to measure the roughness of this copied image, we measured the area ratio (%) of the area where the optical density is 0.6 or less using a photo pattern analyzer (product name: PDA-25OA, manufactured by S-Riki).The results are as follows. It was as follows.

Thus, it was confirmed that the image quality of the photoreceptor having a single layer of conductive polymer was excellent.

In the above table, "Reference Example" refers to the case where the photoreceptor manufactured in Example 1 without forming a single layer of conductive polymer was used.

Claims (1)

[Claims] 1. In an electrophotographic photoreceptor having a conductive support or a support whose surface is conductively treated, a photoconductive layer containing a photoconductor in a binder, and an insulating layer, the connection between the photoconductive layer and the support is An electrophotographic photoreceptor characterized by having a single layer of conductive polymer between them.