JPH0353627B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor, and particularly to an electrophotographic photoreceptor having a protective layer.

The electrophotographic photoreceptor is made of a vapor-deposited film of Se or Se alloy,
A photosensitive layer such as a coating film in which inorganic particles such as ZnO or CdS or organic pigments such as azo pigments or cyanine pigments are dispersed in a binder resin is provided on a support. It is used in an electrophotographic method in which an image is formed, the developed toner image is transferred to transfer paper, and then fixed to obtain a copy.

A photoreceptor with an exposed photosensitive layer on its surface may be scratched on the surface during handling or cause clogging of toner, thereby shortening the life of the photoreceptor. In order to overcome this drawback, conventional attempts have been made to provide a surface layer different from the photosensitive layer on the surface of the photoreceptor. As the surface layer, an insulating layer is used on the one hand, and a protective layer is used on the other hand. The former insulating layer is a film made of electrically insulating resin or the like provided on the surface of the photoreceptor, and is statically charged through the steps of primary charging → secondary charging → image exposure or primary charging → reverse polarity secondary charging → uniform exposure. A latent image is formed.
A photoreceptor with this insulating layer can have a thick insulating layer,
Further, although it has the advantage of increasing mechanical strength, it has the disadvantage that the latent image forming process is a special process and that it is difficult to remove the charge from the latent image. The latter protective layer has a lower resistance than the insulating layer, and forms an electrostatic latent image by the so-called Carlson method of charging→image exposure. Although a latent image can be formed on a photoreceptor having this protective layer by the Carlson method, the residual potential is high, and the film is thinner than an insulating layer and has inferior mechanical strength.

Therefore, attempts have been made to add electrical resistance modifiers such as quaternary ammonium salts to the protective layer to prevent the accumulation of charges on the surface or inside the protective layer.
Although this attempt makes it possible to reduce the residual potential to some extent, it has the drawback that the charged potential changes due to the influence of humidity. Furthermore, the charge on the surface of the protective layer is injected into the photosensitive layer and discharged during the subsequent image exposure step or development step, resulting in a reduction in the latent image potential.

The present invention relates to the improvement of a photoreceptor having this latter protective layer, and an object of the present invention is to provide a photoreceptor that eliminates these conventional drawbacks.

The object of the present invention is to sequentially form a photoconductive layer, an intermediate layer made of a cured product containing a zirconium complex and a silane coupling agent, and a protective layer in which a conductive metal oxide is dispersed in a binder resin on a conductive support. The conductive oxide fine powder has a particle size distribution of 5% by weight or less of particles with a particle size of 5 μm or more and a particle size of 0.03 μm.
This can be achieved by using an electrophotographic photoreceptor characterized by containing 20% by weight or less of the following:

The structure of the electrophotographic photoreceptor of the present invention is shown in the accompanying drawings. In the figure, 1 is a transparent protective layer, 2 is an intermediate layer made of a cured product containing a zirconium complex and a silane coupling agent, 3 is a photoconductive layer mainly made of Se, and 4 is a conductive support.

As the protective layer 1, an electronically conductive material in which conductive metal oxide fine powder is dispersed in an organic polymer is used. Especially the average particle size is 0.3μm, preferably 0.15μm
Significant effects can be obtained when using fine metal oxide powder. That is, when the average particle size is 0.3 μm or more, it is opaque, but when it is 0.3 μm or less, it becomes substantially transparent, and light transmission is not hindered. The fine powder used has a particle size distribution in which 5% by weight or less of particles with a particle size of 5 μm or more and 20% by weight or less of particles with a particle size of 0.03 μm or less. If 5% by weight or more of particles with a particle diameter of 5 μm or more is contained, the dispersibility of the fine powder will be poor, causing fine irregularities on the surface of the protective layer, resulting in a decrease in cleaning properties and a decrease in the transparency of the protective layer. Particle size 0.03μm
If the following substances are contained in an amount of 20% by weight or more, the residual potential of the photoreceptor increases.

Specific materials used for such a protective layer include zinc oxide, titanium oxide, tin oxide,
There are powders of metal oxides such as bismuth oxide, indium oxide, and antimony oxide; powders containing tin oxide and antimony oxide in a single particle, and the like. The amount of metal oxide added to the resin is preferably between 3 and 65% by weight.

A preferred protective layer is a layer in which conductive metal oxide powder is dispersed in a binder resin, and the conductive metal oxide powder is particularly preferably a powder containing tin oxide and antimony oxide in the same particle. Here, containing tin oxide and antimony oxide in the same particle means a solid solution or fused body of tin oxide and antimony oxide.

As the resin for dispersing the above powder, any resin capable of forming a film can be used. Specifically, polyester resin, polycarbonate resin, fluororesin, polystyrene resin, cellulose resin, vinyl chloride resin, polyurethane resin, acrylic resin, epoxy resin, silicone resin, alkyd resin, vinyl chloride-vinyl acetate copolymer resin, etc. are used. be able to. The thickness of the metal oxide dispersed layer is preferably between 2 and 30 μm, particularly between 5 and 15 μm.

The protective layer can be formed by spraying method, dabbing method,
This can be done by using a known technique such as the blade method.

The intermediate layer 2 must have a higher resistance than at least the upper protective layer 1, which has a low insulation property. Further, the intermediate layer 2 must not be immersed in at least the solvent used for coating the upper protective layer.

In addition to serving as a barrier layer that suppresses charge injection from the surface and increases electrostatic contrast, this intermediate layer can also function as an adhesive layer between the photoconductor and the protective layer.

The intermediate layer is formed by a dried and cured solution of a zirconium complex and a silane coupling agent. These zirconium complexes and silane coupling agents can be mixed in any proportion.

Examples of zirconium complexes suitable for the intermediate layer include acetylacetone complexes such as zirconium acetylacetonate and zirconium trifluoroacetylacetonate. Examples of silane coupling agents suitable for the intermediate layer include the following. Vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β(aminoethyl)
γ-aminopropyltrimethoxysilane, N-β
(aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane,
Methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmonomethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, monophenyltrimethoxysilane.

Although the thickness of the intermediate layer can be set arbitrarily, it is preferably 10 μm or less, particularly 1 μm or less. The formation of this intermediate layer is carried out at 50°C to
This can be done by drying and curing by heating to a temperature of 200°C.

The photoconductive layer 3 is a layer that has both charge generation ability and charge transport ability by light irradiation, and may be a single layer or two layers.
It may be laminated with more than one layer. The photoconductive layer is formed primarily of selenium. For example, selenium, selenium-tellurium, selenium-arsenic, selenium-tellurium
Arsenic, zinc oxide, titanium oxide, cadmium sulfide,
Examples include inorganic substances such as cadmium selenide, zinc sulfide, and amorphous silicon, and organic substances such as polyvinylcarbazole and its derivatives, aromatic amines, azo pigments, phthalocyanine, oxazole, triazole, imidazole, and brompyrene. This photoconductive layer can be formed by a known method such as a vacuum deposition method. The thickness of the photoconductive layer can be set arbitrarily, but it is 5 μm to 200 μm, especially 20 μm.
~100 μm is suitable.

Next, the electrophotographic photoreceptor of the present invention will be explained with reference to comparative examples and examples.

Comparative example 1 As ₂ Se ₃ vapor deposited film (60 μm) provided on aluminum pipe
65 parts by weight of polyacrylic urethane and 35 parts of tin oxide/antimony oxide fine powder with an average particle size of 0.3 μm.
Parts by weight were placed in a ball mill together with cellosolve acetate and butyl acetate to disperse them, and an appropriate amount of a curing agent was added thereto, which was coated and dried to obtain a photoreceptor having a 10 μm protective layer. The As ₂ Se ₃ vapor deposited film before this protective layer is applied is positively charged, and the initial potential is set to 900 V.
This operation of exposing the sample to light with a wavelength of 460 mm was repeated for 5 minutes at a rate of 40 times per minute. At this time, the residual potential was stable at 0V. On the other hand, when the As ₂ Se ₃ vapor-deposited film provided with the protective layer was charged and exposed under the above conditions, the initial potential was 120V and the residual potential was stable at 55V. Therefore, the As ₂ Se ₃ photoreceptor with the protective layer had almost no electrostatic contrast.

Example 1 On an aluminum pipe using the same method as Comparative Example 1
A vapor deposited film of As ₂ Se ₃ was formed. Next, 2 parts by weight of zirconium acetylacetonate, γ-
Methacryloxypropyltrimethoxysilane 1
A solution consisting of 1 part by weight and 20 parts by weight of n-butanol was spray applied, dried at 100°C for 2 hours,
An intermediate layer with a thickness of 0.6 μm was provided. Next, the same protective layer as in Comparative Example 1 was provided thereon to a thickness of 10 μm, and charging exposure was repeated in the same manner as in Comparative Example 1, resulting in an initial potential of 960V and a residual potential of 55V. Therefore, the electrostatic contrast of this photoreceptor was 905V, which was the same value as a photoreceptor without a protective layer. When copies were made using this photoreceptor, clear images with no stains in the background were obtained. This resolution is
7 lp/mm, which is equivalent to a photoreceptor without a protective layer. In addition, this photoreceptor can be used at high temperatures and high humidity (30°C, 85°C).
%RH) environment with low temperature and low humidity (10℃, 15%
RH) environment, we were able to obtain good copies with no change in image quality. In addition, when this photoreceptor was placed in a copying machine with a blade cleaning device and a paper peeling section that has a steel peeling claw that is in constant pressure contact with the photoreceptor and 100,000 copies were made, there was no change in image quality, and there was no change in the protection. Good image quality could be obtained without causing any scratches on the layer surface.

Comparative Example 2 When an As ₂ Se ₃ vapor-deposited film prepared in the same manner as Comparative Example 1 was repeatedly charged and exposed without providing an intermediate layer or a protective layer, the initial potential was 910 V and the residual potential was 0 V, as in Comparative Example 1. It was stable. When this photoreceptor was placed in the same copying machine as in Example 1 and copied, a clear image without background smudge was obtained. When copying continued, a small defect was found around the 30,000th copy. That is,
Very thin white streaks appeared in the solid black areas, and there were signs that the white streaks increased with the number of copies, but there were almost no white streaks in the text areas. However, after copying 100,000 sheets, a considerable number of fine white streaks were seen in the solid black areas, and white streaks were also seen in the text.

Example 2 On an aluminum pipe using the same method as Comparative Example 1
A vapor deposited film of As ₂ Se ₃ was formed, and 1 part by weight of zirconium trifluoroacetylacetonate was added thereon.
γ-glycidoxypropyltrimethoxysilane 1
A solution consisting of 1 part by weight and 20 parts by weight of n-butanol was spray applied and dried at 100°C for 2 hours to give a 0.5μ
An intermediate layer of m thickness was provided. Then, on top of this, Comparative Example 1
The same protective layer was provided with a thickness of 10 μm, and when charging and exposure were repeated in the same manner as in Comparative Example 1, the initial potential was
The voltage was 955V, and the residual potential was 55V. Therefore, the electrostatic contrast of this photoreceptor was 900V, which was the same value as the photoreceptor without a protective layer and the photoreceptor of Example 1. Further, when this photoreceptor was used to perform a copy test, an environmental test, and a durability test in the same manner as in Example 1, similar good results were obtained.

[Brief explanation of drawings]

The drawings show the structure of the electrophotographic photoreceptor of the present invention. Symbols in the figure: 1...Low resistance transparent protective layer; 2...Intermediate layer; 3...Photoconductive layer; 4...Electroconductive support.

Claims (1)

[Claims] 1 A photoconductive layer, an intermediate layer made of a cured product containing a zirconium complex and a silane coupling agent, and a protective layer in which a conductive metal oxide is dispersed in a binder resin are sequentially laminated on a conductive support. The conductive oxide fine powder has a particle size distribution of 5% by weight or less of particles with a particle size of 5 μm or more and a particle size of 0.03 μm or less.
An electrophotographic photoreceptor characterized in that the content is 20% by weight or less.