JPH0542664B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor in which a photosensitive layer in which photoconductive material particles are dispersed in a binder made of an insulating polymer material is formed on a substrate. This invention relates to improvements in electrophotographic photoreceptors. Prior Art Photoreceptors using phthalocyanine-based photoconductive materials are disclosed in, for example, JP-A-50-38543, JP-A-51-95852, JP-A-53-64040,
It is described in Japanese Patent Application Laid-Open No. 53-83744. JP-A-56-83743 discloses a technique in which an aliphatic unsaturated carboxylic acid is used as a dispersant in a binder of a photoconductive material in order to improve the smoothness of an electrophotographic photoreceptor. ing. Various photoconductive materials such as CdS are listed as photoconductive materials used here, and anthracene and phthalocyanine are also disclosed among them. However, the dispersant used is a free acid, and there is no mention of a technique for improving the moisture resistance of electrophotographic photoreceptors using fatty acid derivatives. Japanese Patent Publication No. 56-19631 discloses a technique for improving the moisture resistance of a negatively charged photoreceptor such as zinc oxide using a metal soap. However, this document does not describe at all a technique for improving the moisture resistance of an electrophotographic photoreceptor using a phthalocyanine-based photoconductive material and fatty acid derivatives. OBJECTS OF THE INVENTION An object of the present invention is to improve the moisture resistance, surface smoothness, and abrasion resistance of an electrophotographic photoreceptor containing a phthalocyanine-based photoconductive powder. Phthalocyanine-based photoconductive materials are superior to conventional cadmium sulfide and zinc oxide-based photoconductive materials in terms of processability and sensitivity of photoreceptors, have no hygienic problems, and can be used with ultra-wavelength light such as semiconductor lasers. It is also excellent in that it exhibits high sensitivity. However, in this type of electrophotographic photoreceptor, since it is positively charged, a large amount of hydrated H ⁺ ions ((H ₂ O) nH ⁺ ) are generated, which generally has the disadvantage of poor moisture resistance. As a countermeasure against this problem, various binder resins have been proposed, but they have been unable to provide a practically sufficient electrophotographic photoreceptor due to poor sensitivity and the like. The present invention has been made to improve the above-mentioned problems, and an object of the present invention is to improve the electrophotographic properties, particularly the moisture resistance, of an electrophotographic photoreceptor using a phthalocyanine-based photoconductive material. Structure of the Invention That is, the present invention provides an electrophotographic photoreceptor in which a photosensitive layer formed by dispersing phthalocyanine-based photoconductive material powder in a binder is formed on a substrate, and the photosensitive layer contains a fatty acid derivative. An electrophotographic photoreceptor is provided. The fatty acid derivatives used in the present invention include esters, amides, acid anhydrides, etc. of aliphatic carboxylic acids having 4 to 23 carbon atoms, alicyclic carboxylic acids having 4 to 23 carbon atoms, aromatic-aliphatic carboxylic acids, etc. Illustrated. The amount of the aliphatic derivative added is 0.1 to 15 parts by weight per 100 parts by weight of the phthalocyanine-based photoconductive material. If the amount added is less than 0.1 parts by weight, the effect will not be exhibited, and if the amount added is more than 15 parts by weight, the sensitivity will deteriorate.
It repeatedly becomes unstable. The fatty acid derivative can be mixed into the electrophotographic photoreceptor by dispersing it as it is together with the photoconductive powder, by dispersing the fatty acid derivative in the photoconductive powder and drying it, or by raising the fatty acid derivative to a temperature above the melting point in a dry process and fixing it. It is possible to use a method such as The photoconductive fine powder and metal soap described in Japanese Patent Publication No. 56-19631 are mixed by a wet method,
When the method of performing heat treatment after drying is applied to the copper phthalocyanine-based photoconductive material of the present invention, the phthalocyanine particles undergo crystal transition or secondary agglomeration depending on the selected solvent, resulting in decreased dispersibility. There are drawbacks such as. As the phthalocyanine-based photoconductive material used in the present invention, any of the per se known phthalocyanines and their derivatives can be used, and specifically, aluminum phthalocyanine, vanadium phthalocyanine, tin phthalocyanine, antimony phthalocyanine, barium phthalocyanine,
Beryllium phthalocyanine, vanadium phthalocyanine, cobalt phthalocyanine, cobalt chlorophthalocyanine, copper-4-aminophthalocyanine, copper-4-chlorophthalocyanine, copper phthalocyanine, dysprosium phthalocyanine, germanium phthalocyanine, holmium phthalocyanine, iron phthalocyanine, iron polyhalophthalocyanine, lead phthalocyanine, Lead polychlorophthalocyanine, cobalt hexaphenyl phthalocyanine,
Metal phthalocyanines such as platinum phthalocyanine and zinc phthalocyanine; metal-free phthalocyanine compounds such as dialkylaminophthalocyanine, tetraazophthalocyanine, tetramethyl phthalocyanine, and tetraphenyl phthalocyanine are suitable, and these can be used alone or in combination. In addition, phthalocyanine derivatives in which the hydrogen atom of the benzene nucleus in the phthalocyanine molecule is substituted with at least one type of electron-withdrawing group selected from the group consisting of a nitro group, a cyano group, a halogen atom, a sulfone group, and a carboxy group; Phthalocyanine-based photoconductivity obtained by mixing at least one unsubstituted phthalocyanine compound selected from the above phthalocyanine compounds with an inorganic acid capable of forming a salt with them, and precipitating the mixture with water or a basic substance. Material compositions can also be used. In this case, the electron-withdrawing group-substituted phthalocyanine derivative has 1 to 1 substituents in one molecule.
16 arbitrary ones can be used, and the composition ratio of the electron-withdrawing group-substituted phthalocyanine derivative and other unsubstituted phthalocyanine compounds is such that the number of the former substituents is 0.001 per phthalocyanine molecule in the composition. It is preferable that the number is 2 to 2, preferably 0.002 to 1. Inorganic acids that can form a salt with the phthalocyanine compound used in producing the phthalocyanine-based photoconductive material composition include sulfuric acid, orthophosphoric acid, chlorosulfonic acid, hydrochloric acid, hydroiodic acid, and hydrofluoric acid. , hydrobromic acid, etc. Among the photoconductive materials, those particularly suitable for achieving the object of the present invention include metal-free phthalocyanine, copper phthalocyanine and derivatives thereof,
Examples include nuclear halogen-substituted derivatives. Regarding the blending ratio of the phthalocyanine-based photoconductive material and the binder, as the amount of the former increases, sensitivity improves, but dark decay increases significantly, making it difficult to retain charge and impractical. On the other hand, if the amount of the former decreases, the dark decay will decrease but the sensitivity will decrease, so the amount of photoconductive material should be 5 to 100 parts by weight, preferably 15 to 60 parts by weight, per 100 parts by weight of the binder. It is preferable to make it a section. The electrically insulating binder resin in the present invention includes electrically insulating thermoplastic resin, photocurable resin,
Any of the binders commonly used in the past, such as photoconductive resins, can be used. Examples of suitable binder resins include, but are not limited to, saturated polyester resins, polyamide resins, acrylic resins, ethylene-vinyl acetate copolymers, ionically crosslinked olefin copolymers (ionomers),
Styrene-butadiene block copolymer, polycarbonate, vinyl chloride-vinyl acetate copolymer,
Thermoplastic binders such as cellulose ester and polyimide; Thermosetting binders such as epoxy resins, urethane resins, silicone resins, phenolic resins, melamine resins, xylene resins, alkyd resins, and thermosetting acrylic resins; photocurable Resin: Photoconductive resin such as poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, etc. These electrically insulating resins are measured individually and have a
It is desirable to have a volume resistivity of 10 ¹⁴ Ω·cm or more. The photoconductive layer structure in the present invention may be a single layer structure in which a phthalocyanine-based photoconductive material is dispersed in a binder resin, or a known photoconductive layer structure such as a functionally separated structure using a charge transporting material such as hydrazone. Conductive layer configurations can be used. As the conductive support, copper, aluminum,
A foil or plate of silver, iron, nickel or the like is used in the form of a sheet or drum, or these metals are vacuum-deposited or electrolessly plated on a plastic film or the like. Effects of the Invention By using the present invention, the moisture resistance of a photoreceptor using a phthalocyanine-based photoconductive material is improved, and
Surface smoothness and abrasion resistance are also improved, and an electrophotographic photoreceptor with excellent practicality can be obtained. Example 1 50 parts by weight of copper phthalocyanine and 0.5 parts by weight of trinitrocopper phthalocyanine were dissolved in 500 parts by weight of 98% concentrated sulfuric acid with thorough stirring. The solution was poured into 2000 parts by weight of water to precipitate a mixture of copper phthalocyanine and trinitrocopper phthalocyanine, which was then filtered, washed with water, and dried at 120°C under reduced pressure. 30 parts by weight of this photoconductive material composition, 56 parts by weight of thermosetting acrylic resin, 14 parts by weight of melamine resin, and 2 parts by weight of stearamide (Aramide HT) are mixed into 180 parts by weight of a mixture of butyl acetate and cellosolve acetate (1:1). Pour into a ball mill together with the resin solution dissolved in 48
A photoconductive paint was prepared by kneading and dispersing for a period of time. This paint was applied onto an aluminum substrate so that the film thickness after drying was about 10 μm, and after drying, it was cured to prepare an electrophotographic photoreceptor. The obtained photoconductor was subjected to +
The half-reduced exposure amount E 1/2 and the residual potential V _R required to attenuate the charging potential V ₀ of the photoreceptor of the charged liquid to 1/2 by charging for 0.2 seconds with a primary charging voltage _of 7 KV.
was measured. In addition, we continuously formed duplicated images, evaluated the image quality after making 1000 copies, and then left the photoreceptor in an atmosphere of 85% RH at 30°C for 3 days to condition the humidity. The image quality was then measured. The results obtained are shown in Table-1. Example 2 A photoreceptor was prepared in the same manner as in Example 1, except that 3 parts by weight of fatty acid ester wax (Loxiol G41) was used in place of stearamide. The characteristics of this photoreceptor were evaluated in the same manner as in Example 1. The results are shown in Table-1. Comparative Example 1 A photoreceptor was prepared in the same manner as in Example 1 except that stearamide was not used. The characteristics of this photoreceptor were evaluated in the same manner as in Example 1, and the results are shown in Table 1. 【table】

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor in which a photoconductive layer formed by dispersing photoconductive powder in a binder is formed on a substrate, wherein the photoconductive powder is a phthalocyanine-based photoconductive powder. An electrophotographic photoreceptor, characterized in that the photoconductive layer contains a fatty acid derivative. 2 The amount of fatty acid derivative added to the resin is 0.1~
1. The electrophotographic photoreceptor according to item 1, wherein the content is 10% by weight. 3. The electrophotographic photoreceptor according to item 1, wherein the phthalocyanine-based photoconductive powder is copper phthalocyanine.