GB1059137A - Electrophotographic recording members and processes of preparing same - Google Patents

Abstract

1,059,137. Electrophotographic materials. ADDRESSOGRAPH - MULTIGRAPH CORPORATION. Nov. 6, 1963 [Nov. 29. 1962], No. 43884/63. Heading H1K. The upper surface of a substrate for an electrophotographic material is given a pre-coat before the photoconductive layer is' applied. The pre-coat contains the reaction product of a water-soluble aminoplast pre-condensate and a film-forming polymeric material having reactive carboxyl or hydroxyl groups. Suggested aminoplasts include various methylated methylol melamines, other alkylated melamine formaldehyde resins, urea - formaldehyde, aniline -formaldehyde, and cyanamide-formaldehyde. Suggested polymers are an interpolymer of styrene, hexyl acrylate, acrylonitrile, and methacrylic acid; polyvinyl alcohol; carboxylated styrene-maleic anhydride copolymers; carboxylated ethylene-maleic anhydride copolymers; crotonic acid-vinyl acetate copolymers; and hydroxy ethyl cellulose. The pre-coat may contain materials to improve its flexibility. For example, the composition may contain polyvinyl acetate. Common substrate materials may be used including fabrics and organic and metallic foils but an electrically conductive paper which may have a sealing coat on its under surface is preferred. The sealing coat may consist of -the pre-coating .material. In the examples the substrate consists of a bleached sulphite paper. The photoconductive layer consists of a particular photoconductor dispersed in a resinous binder. Many suitable photoconductors are listed. The precoat is formed by applying an aqueous material to the substrate. This is either an aqueous solution of the components or, a mixture of a solution of the aminoplast precondensate and a latex or dispersion of the polymeric material. "The composition may contain a stabilizer to delay thereaction between the main components. Spray or roll coating is suitableimmersion coating may be used if a sealing coat of the same composition as the pre-coat is .wanted. The pre-coating composition is cured by heating in a hot air oven to 250-360‹ F. for from 30 sees. to 5 mins. A dispersion of the photoconductor - in a resin solution is . then applied. The pre-coat prevents the solvent used from penetrating the substrate. The material is heated in hot air to 200-250‹ F. to remove volatiles-the solvent may. be removed in other ways if desired. In the specific examples the photocondtictive layer consists of zinc oxide and either a silicone resin or a styrene-butadiene copolymer as binder. The pre-coating compositions were of four main types:-(A) Dimethyl trimethylol melamine, water, the four component acrylic-styrene interpolymer mentioned above, and ammonia. (The ammonia acts as a stabilizer.). (B) Dimethyl trimethylol melamine, water, polyvinyl acetate, and either polyvinyl alcohol or hydroxy ethyl cellulose. (C) Ureaformaldehyde, water, and a copolymer of maleic anhydride with either styrene or ethylene. (D) Dimethyl trimethylol melamine, water, polyvinyl acetate, and copolymer of vinyl acetate and crotonic acid. The pre-coat increases the surface resistivity of the support.