JPS6032054A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain surface smoothness, to reduce electric resistance, and to prevent accumulation of residual potential by using a coating material prepared by dispersing a powder of Ti oxide coated with a layer made of Sb oxide and Sn oxide into a resin. CONSTITUTION:A conductive substrate is coated with the layer of a coating material prepared by dispersing a mixture composed essentially of a Ti oxide powder coated with a layer made of oxides of Sb and Sn into a resin. Since the coated powder itself has a specific resistivity of 2-500OMEGA.cm and its raw material is a very small Ti oxide powder having 0.1-0.5mum average particle diameter, even the coated powder has only an average particle diameter of 0.2-0.6, thus improving dispersibility. A preferable proportion of the coating material of the total coated Ti oxide powder is 5-67%, and the coating material is composed of 1-20% Sb oxide and the rest of Sn oxide. The coating material is prepared by dispersing such a coated powder into the soln. of a binder resin, preferably, a hardenable resin, such as hardenable rubber or polyurethane resin. A suitable volume resistivity of the resin contg. the dispersed coated Ti oxide is <=10<13>, especially, <=10<12>OMEGA.cm.

Description

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

An electrophotographic photoreceptor basically consists of a substrate and a photosensitive layer. However, improvements in adhesion between the substrate and the photosensitive layer, improvement in coating properties of the photosensitive layer, protection of the substrate, covering defects on the substrate, protection against chemical destruction, charge injection from the substrate to the photosensitive layer, etc. In order to improve properties, it is effective to provide an undercoat layer between the substrate and the photosensitive layer.

Conventionally known materials for the undercoat layer include polyvinyl alcohol, polyvinyl methyl ether, poly-N-vinylimidasol, ethyl cellulose, methyl cellulose, ethylene-acrylic acid copolymer, casein, gelatin, and polyamide.

The first characteristic required of the undercoat layer is electrical characteristics. Since it is used in an electrophotographic photoreceptor, it is important not to affect the electrophotographic properties, and for this purpose it is necessary to have low electrical resistance. When the electrical resistance is high, a charged potential is applied to the undercoat island, and a fog is generated in one image as a so-called residual potential.

Furthermore, it is necessary that the electrical resistance is unaffected by changes in the external environment, in particular by changes in atmospheric humidity. For example, if the humidity becomes low and the electrical resistance increases, it will cause fogging.

Such properties are required of the undercoat layer, but it has been difficult to obtain good properties in the case of a single resin layer. Therefore, the thickness of the resin layer is made very thin, or if necessary, conductive powder (metal powder such as copper or scissors) is dispersed in the resin. However, reducing the thickness of the resin layer has the disadvantage that its performance as an undercoat layer is not sufficient, and on the other hand, the undercoat layer in which metal powder is dispersed has rough particles on the reinforcing metal. There was a drawback that the surface properties of the pulling layer deteriorated.

An object of the present invention is to provide an electrophotographic photoreceptor that eliminates the above-mentioned drawbacks.

Another object of the present invention is to provide an electrophotographic photoreceptor having an intermediate layer capable of eliminating defects in a rough substrate in terms of current collection.

Another object of the present invention is to provide an electrophotographic photoreceptor having a smooth surface between a rough mj substrate and a photoreceptor 1-, and an intermediate layer that can be formed thickly.

Paint used for the intermediate layer to achieve the purpose of the present invention (required conditions are (1) surface smoothness (2) low electrical resistance and no accumulation of residual charge due to its characteristics) (331E photographic properties should not be adversely affected (4) Adhesion to the substrate should be sufficient (5)
) It must have sufficient solvent resistance for the paint applied thereon.

The present invention is characterized by using a paint in which titanium oxide powder, which forms a coating layer consisting of antimony oxide (81) 203) and tin oxide (sno2), is dispersed in a resin. The characteristics of this powder are (1) the specific resistance of the powder itself is about 2 to 500j7 crn; (2) Since the raw material is titanium oxide, the average particle size is very slender, 0.1 to 0.5μ, and even after memory treatment, the average particle size is 0.2 to 0.5μ.
Good filter dispersibility with 6μ. (3) For the same reason, paint J - good surface smoothness. (4) The color is light gray, which has little effect on electrophotographic properties, and is effectively used in the present invention.

Antimony oxide has the ability to lower the resistance of tin oxide by forming a solid solution with tin oxide.

There are powders of titanium oxide with crystal systems of rutile type and anatase type, but the present invention may use either of them, and is not particularly limited. The amount of the coating layer relative to the titanium oxide powder is preferably 5 to 67% in total. If it is less than this, the specific resistance will not be too low and the conductivity will not be sufficient. In addition, when the grains are exceeded, disadvantages such as a decrease in mechanical strength, coarsening of particles, and high cost occur.

The composition of the coating layer is 1 to 20% antimony oxide, and the remainder is tin oxide. When the amount of antimony oxide is less than 1%, good conductivity cannot be obtained, and when it exceeds 20%, the butterfly powder becomes blue-black. The treatment method for forming the coating layer is to disperse titanium oxide powder in hot water, add an acetone solution of tin chloride and antimonochloride, and hydrolyze it to form tin oxide and oxide on the titanium oxide surface. A method of precipitating antimony, a method of spraying an aqueous solution of tin chloride and antimony chloride onto titanium oxide powder heated to a high temperature of about 300°C, and forming tin oxide and antimony oxide through thermal decomposition, 50-10
A solution of tin chloride and antimony chloride dissolved in sufficient hydrochloric acid water to prevent hydrolysis and an ammonia aqueous solution were simultaneously added to an aqueous suspension of titanium oxide at 0°C to prevent hydrolysis due to neutralization, resulting in the formation of a titanium oxide surface. There are methods such as precipitating tin oxide and antimony oxide.

A paint is obtained by dispersing the powder obtained by such a method in a binder resin solution.The resin must (1) have strong adhesion to the substrate, and (2) have good dispersibility of the powder. and (5) have sufficient solvent resistance. In particular, curable rubber, polyurethane resin, epoxy resin, alkyd resin, phenol resin, polyester resin, Thermoset flanks such as silicone resins, acrylic-melamine resins, etc. are preferred.

The volume resistivity of the resin in which the surface-treated titanium oxide is dispersed is suitably less than 1015 Ω, preferably less than 1012 Ωd. Therefore, in the coating film, the proportion of surface-treated titanium oxide is preferably 50% or more by volume and 60% or more by weight.

Furthermore, if the resistivity is sufficiently low, it may be effective to use other pigments in combination to reduce the cost of the paint or to increase the whiteness of the paint. Most common titanium oxide powders are suitable. Furthermore, in order to improve the smoothness of the paint surface, it is preferable to use K and titanium oxide powders whose surfaces are treated with alumina. There is a method in which titanium hexameride powder is dispersed in an aqueous solution of salt, an alkali is added thereto to precipitate aluminum hydroxide into the titanium oxide powder, and then the powder is ignited.

The above pigments are dispersed in a conventional resin solution and made into a paint. il coated on the substrate of the child photographic photoreceptor;
After being applied, it is dried and, if necessary, heated to form a paint layer (intermediate layer). Although the film thickness depends on the degree of defects in the rough substrate, it is preferably about the square of the maximum surface roughness of the substrate.

Here, the maximum surface roughness of the paint layer must be L, which must be 2μ or less. If the size is larger than this, defects may occur in the copied image. Since this maximum surface roughness varies depending on the composition of the powder and resin, the film thickness, etc., it is necessary to determine the optimum value.

A photosensitive layer is formed on this paint layer, and depending on the 1M type of material of the photosensitive layer, a 7-lead carrier may be injected from the layer into the photosensitive layer. When such a phenomenon occurs, the potential attenuation of the photosensitive layer becomes large and image formation becomes difficult. In such a case, injection of free carriers can be prevented by further providing a thin second resin layer containing no conductive fine powder on the layer containing the above-mentioned isoelectric fine powder. This second resin layer is made of, for example, a water bath resin such as polyvinyl alcohol, polyvinyl methyl ether, polyacrylic acids, methyl cellulose, ethyl cellulose, polyglutamic acid, casein, ceratin, or starch.

It can be formed using melamine, polyamide, epoxy, polyurethane, polyglutamic acid ester, or the like. Among these, polyamide resins are preferred in terms of coatability, specific resistance, solvent resistance for photosensitive layers, and the like. However, the adhesion properties differed greatly depending on the type of polyamide resin wire and the type of binder resin used in the first layer.

Therefore, the present inventor investigated resins and found that when a resol type phenol resin was used as the binder of the first OM, the polyamide resin had strong adhesion to it. A resol type phenolic resin is a resin obtained by reacting a phenol compound and an aldehyde compound under an alkali catalyst, and can be used as a thermosetting resin in paints.

The curing temperature is about 120 to 200°C.

The polyamide resin is preferably a linear polyamide, and optimally a low to non-crystalline copolymerized nylon and/or type 8-nylon so that it can be applied in the form of a solution. These are methanol, 〒11JII, 4RIN-嬌/7'
1"7m, -1m, rym=sii. Aromatic hydrocarbons such as toluene and xylene may be added for solution stability. The thickness of the polyamide resin layer is approximately 0.1 to 2μ. If it is thin, coating defects are likely to occur.
If it is too thick, it will cause residual potential.

To explain in more detail about the electrophotographic photoreceptor of the present invention, first, the substrate is made of metal such as aluminum, brass, or stainless steel, or polyethylene terephthalate, polybutylene terephthalate, phenol a fat, polypropylene, nylon, polystyrene, etc. It is used by molding materials such as polymeric materials and hard paper into a cylindrical shape, or by making them into films or foils. In the case of an insulator, it is necessary to perform a four-electrode process, which includes methods such as impregnation with a conductive substance, lamination of metal foil, and metal vapor deposition. A coating layer containing titanium oxide having a 'wL coating layer according to the present invention is provided on the substrate, a polyamide resin layer is further provided as required, and a photosensitive layer is formed thereon.

The photosensitive layer is formed by coating one-color sensitized zinc oxide, selenium powder, undiagnosed silicone powder, polyvinylcarnosol, phthalocyanine pigment, xaxadiazole pigment, etc. together with a binder resin as required.

In addition, when using organic photoconductive materials, an effective method for improving properties is to use a charge generation layer that generates stain carriers upon exposure and a charge transport layer that has the ability to move the generated charge carriers. Sometimes they are combined.

The charge generation layer is made of azo pigments such as Sudan Red, Guianpuru, Jenas Green B, Algol Yellow,
Quinone pigments such as pyrenequinone and indanthrene brilliant violet RRP, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, bisbenzimidazole pigments such as India First Orange toner, phthalocyanine pigments such as copper phthalocyanine, quinacridone pigments, and biryllium thread. It is formed by dispersing a charge generating substance such as a dye in a binder resin such as polyester, polystyrene, polyvinyl acetate, acrylic, polyvinyl butyral, polyvinylpyrrolidone, methylcellulose, hydroxypropylmethylcellulose, or cellulose esters. Alternatively, it can also be formed by vapor deposition or the like. , the thickness of the charge generation layer is 0.85-0.2μ
That's about it.

In addition, the charge transport layer may contain polycyclic aromatic compounds such as anthracene, pyrene, phenanthrene, coronene, etc., or indole, carbazole, oxazole, susooxazole, thiazole, imidazole, pyrazole, etc. in the main chain or side chain.
It is formed by dissolving a hole-transporting substance such as a compound having a nitrogen-containing cyclic compound such as oxadiazole, pyrazoline, thiadiazole, or triazole, or a hydrazone compound in a resin that has film-forming properties. This is because the charge generating substance generally has a low molecular weight and has poor film-forming properties by itself.

Such resins include polycarbonate, polyarylate, polystyrene, and polymethacrylate! Examples include L-acid esters, styrene-methyl methacrylate copolymers, polyesters, styrene-acrylonitrile fluoropolymers, polysulfones, and the like.

The thickness of the charge transport layer is approximately 5 to 20 microns.

Since the electrophotographic photoreceptor according to the present invention may have a rough substrate surface, it is possible to significantly reduce the cost of processing the substrate. Furthermore, according to one aspect of the present invention, the electrophotographic photoconductor company has a resin layer in which powder is dispersed under the photosensitive layer. Even when used in so-called laser beam printers that use light, it has the property of preventing phenomena such as interference caused by reflection of laser light on the substrate surface, so it can be effectively used in such applications. .

Solid Line Example 1 An aluminum cylinder of 60φ x 260+ra was prepared as a base. The maximum roughness of the surface was measured to be 5μ.

On the other hand, tin oxide containing 10 parts of antimony oxide was added to 1 part per 1 part of tin. Titanium oxide powder (product name + ECT62, Titanium Industry ■#) coated with 75 pieces of water
Titanium oxide powder coated with 2% by weight of alumina (surface product name: 5R)
-1. Vinegar Chemical Industry ■l! 50 parts of the two types of powder were mixed with resol type pheno-#411 fat (product name: Zolai Ophene 5).
010, manufactured by Dainippon Ink Chemical Company, solid content: 58%), and 60 parts of methyl ethyl ketone. After thorough mixing, the mixture was dispersed in a ball mill for 6 hours.

After adjusting the viscosity of this paint to 9Dcp, it was applied to the above substrate by dipping, and after air-drying for 10 minutes,
It was heat cured at ℃ for 20 minutes. In this way, a paint layer with a thickness of 18 μm was formed. The maximum roughness of this surface is 0.75
It was μ.

Next, copolymerized nylon resin (product name: Amilan CM80
00, manufactured by Toshi Corporation) in a mixed solution of 60 parts of methanol and 40 parts of butanol, and the solution was dip coated onto the above layer to form a polyamide resin layer with a thickness of 1 μm.

Next, 10 parts of a disazo pigment with the following structural formula, 6 parts of cellulose butyrate resin (product name 2CAj3-381 manufactured by Eastman Chemical Company), and 6 parts of Schifa hexanone were added to 200 parts in a sand mill using 1φ glass beads. Time was distributed. Add 100 parts of methyl ethyl ketone to this dispersion,
It was applied by dip coating on the above polyamide resin layer and heated to 100°C for 10
After heating and drying for a few minutes, a charge-generating counterfeit with a coating weight of 7 m5 of b O, I Y was obtained.

Next, 10 parts of a hydrazone compound having the following structural formula and a styrene-methyl methacrylate copolymer resin (trade name!
Add 15 parts of MS200g (manufactured by Tetsusei Kagaku ■) to 80s of toluene.
dissolved in. This solution was applied onto the charge generation layer for 10 minutes.
The electrophotographic photoreceptor manufactured in this manner, in which a charge transport layer having a thickness of 16 μm was formed by drying with hot air at 0° C. for 1 hour, is referred to as (1).

For comparison, a photoreceptor was also prepared as shown below.

(2)...Those in which a photosensitive layer is formed on the substrate without forming an undercoat layer or polyamide resin layer; (5)...Those in which an undercoat layer is formed and a photosensitive layer is formed thereon. .

(4) A polyamide resin layer is formed on a substrate without an undercoat layer, and a photosensitive layer is formed on top of the polyamide resin layer.

These photoreceptors were subjected to -5,6KV corona charging, image exposure, dry toner development, toner transfer to plain paper, and cleaning with a urethane rubber blade (hardness 70°, pressure 10gw/+-angle [20' to the photoreceptor). The electrophotographic characteristics were evaluated by installing the photocopy machine into an electrophotographic copying machine having a double process.

As described above, (1) was the most excellent photoreceptor.

Note that in the photoreceptor (4), the roughness of the substrate affected the image quality, but in order to improve the image quality, the surface roughness of the substrate had to be finished to 0.5 μm or less. In comparison, (1) was inexpensive.

Example 2 Titanium oxide powder coated with tin oxide containing 90% antimony oxide at a concentration of 70% by weight relative to titanium oxide (
50 parts of alumina-treated titanium oxide powder (product name: 5R-IT% manufactured by Sakai Chemical Industry Co., Ltd.) and 4 parts of alumina-treated titanium oxide powder (product name: w-io produced by Mitsubishi Metals) were mixed with a resol-type phenolic resin (trade name: NIBRAIO). - Fen 506υ, manufactured by Dainippon Ink@)
40 copies.

The mixture was dispersed in a ball mill for 6 hours with a solution consisting of 60 parts of methyl ethyl ketone.

When an electrophotographic photoreceptor was manufactured using this paint in the same manner as in Example 1, the photoreceptor produced good image quality. The maximum roughness of the surface of the paint layer was 0.8μ.

Example 5 Titanium oxide powder coated with tin oxide containing 9% antimony oxide so that the weight of titanium oxide was 70%
Product name: W-10, manufactured by Mitsubishi Metals ■) 95it-resol type phenolic resin (Product name: NIBRIOPEN 503
0. Dainippon Ink@) 40 parts, methyl ethyl ketone 6
Dispersion was carried out in a ball mill for 6 hours with a solution consisting of 0 parts.

An electrophotographic photoreceptor was manufactured in the same manner as in Example 1 using this paint. It was a photoreceptor that provided good drawing material. The maximum surface roughness of the paint layer was 0.9μ.

Example 4 The same treatment as in Example 2 was carried out except that untreated titanium oxide powder was used instead of the alumina-treated titanium oxide powder.

The maximum roughness of the surface of the paint layer was 0.9μ. The photoreceptor provided good image quality.

Patent applicant: Agent of Gyanon Co., Ltd. Patent attorney: Yute Kano Continuation Amendment: June 26, 1980 Manabu Shiga, Commissioner of the Patent Office 1, Indication of case: 1981 Property Application No. 140562, 2, Name of invention Electrophotographic photoreceptor・3. Relationship with the person making the amendment Patent applicant address 3-30-2 Shimomaruko, Ota-ku, Tokyo Name (1)
00) Canon Co., Ltd. Representative: Ryu Kaku 3rd Department 4, Agent address: 66, 2-2-4, Shibuya, Shibuya-ku, Tokyo Subject of amendment Detailed explanation column 7 of the specification, Contents of amendment (1) Specification No. 15 The structural formula of the hydrazone compound on the 12th line of the page is supplemented as follows: H1=-4,

Claims (1)

[Claims] (1) An electrophotographic photoreceptor characterized in that a coating layer comprising titanium oxide powder as a main component and dispersed in a resin is provided on a conductive substrate, forming a coating layer consisting of antimony vide and tin oxide. (2) The electrophotographic photoreceptor according to claim 1, which has a polyamide resin layer on a coating layer in which the binder resin is a resol type phenolic resin.