Patent GB-883783-A (GB)
Title: A composite sheet material for electrophotography
IPC: G03G5/05
Filed: 1957-11-12
Abstract: 883,783. Electro-photographic plates. AGFA A.G. Nov. 12, 1957 [Nov. 14, 1956], No. 35254/57. Class 37. An electro-photographic plate consists of a layer comprising a photo-conductive substance, a binding agent and a water-repellent material, coated on a support. The photo-conductive substance may be sulphur, selenium, an oxide, sulphide or selenide of cadmium, mercury, antimony, bismuth, thallium, molybdenum, aluminium, lead or zinc, arsenic trisulphide, cadmium arsenide, lead chlorate, anthracene, benzidine, anthraquinone, acenaphthene fluoranthene, naphthalene, chrysene, quinone, gallic acid, microcrystalline paraffin wax, terphenyl or p-diphenyl benzene, benzanthrone, 1,5 or 1,4-dicyanonaphthalene, aminophthalodinitrile, or nitrophthalodinitrile. Suitable film-forming binding agents are as follows: melamineformaldehyde, urea-formaldehyde and xyleneformaldehyde resins, polymers based on vinyl chloride, vinylidene chloride, vinyl ethers, acrylic esters, methacrylic esters or acrylic amides (e.g. methacrylic amide), aromatic vinyl compounds such as styrene, iso-olefines (e.g. isobutylene), copolymers of vinyl chloride and butyl acetate or of vinylidene chloride and butyl acrylate, synthetic elastomers (e.g. copolymers of butadiene and styrene or of butadiene and acrylonitrile), copolymers of dienes with preponderant proportion of styrene and/or acrylonitrile or other vinyl compounds, polyamides, polyurethanes, polyesters of polycarboxylio acids and polyhydric alcohols, polycarbonates, - cellulose esters, and rubber. The water-repellent material may be a paraffin or other high molecular weight hydrocarbon, a complex compound of Werner type in which a trivalent nuclear chromium atom is co-ordinated with an acrylic carboxylic acid group having at least ten carbon atoms, a fatty acid salt of a polyvalent metal such as chromium, zirconium, titanium or aluminium, or a metal compound capable of hardening gelatine or other proteins, such as zirconium oxychloride, phosphotungstic acid, chrome alum, chromiacetate, chromic acid, cerous nitrate or alum. A suitable mixture of a waterrepellent substance, a binding agent, and a photo-conductive substance is coated on a plate of zinc, aluminium or brass, or on a thin sheet of paper, cellulose hydrate, a cellulose ester or a polyamide. In one embodiment 120 c.c. of a 30% aqueous dispersion of a heat-hardenable melamine-formaldehyde resin, 110 c.c. of water and 40 grams of zinc oxide are ball-milled together. 1 c.c. of a 3% solution of zirconium oxychloride is added to the dispersion which is then coated on a support and dried. Alternatively a quantity of a paraffin may be used instead of the oxychloride, or in combination with it or with formalin or phosphotungstic acid. Other embodiments described use mixtures of zinc oxide with a copolymer of butadiene, acrylonitrile and styrene, and chromstearochloride, or with a copolymer of vinyl chloride, acrylic acid and ethylacrylate, and paraffin. Specifications 469,642, 477,830, 492,742, 627,356, 672,767, 679,533, 775,812, 798,184, 811,165, 818,068 and U.S.A. Specification 2,273,040 are referred to.