ELECTROSTATIC RECORDING MATERIAL AND MANUFACTURE THEREOF

摘要

1468437 Electrostatic recording material KANZAKI PAPER MFG CO Ltd 30 May 1974 [26 Julv 1973 (2) 23 Aug 1973] 23925/74 Heading B2E An electrostatic recording material comprises an electro-conductive base sheet supporting a dielectric layer which contains 10 to 70 wt.% of fine non-conductive, non-photoconductive powder, the powder particles being coated' with an organosiloxane. The base sheet of conductivity 105 to 1011 ohms may be paper which may be primer coated with an aqueous solution of polyvinylbenzenetrimethylammonium chloride, plastics film, cloth or metal foil, the primer coated paper being used in the Examples. The dielectric layer preferably consists of the particles in a polymeric binder such as silicone resin, polyester, polyurethane, alkyd, epoxy, chlorinated rubber, and polymers and copolymers of vinyl chloride, vinyl acetal, vinyl acetal, vinylidene chloride, ethylene, styrene, butadiene, acrylates, methacrylates, acrylonitrile and crotonic acid, and mixtures of the above polymers and copolymers, the layer being formed by air knife coating of aqueous dispersions. The powder used is preferably silica, silicates, CaCO 3 , MgCO 3 , BaSO 4 , CaSO 4 , Al 2 O 3 , MgO, Al(OH) 3 , Ba(OH) 2 , Mg(OH) 2 , quartz sand, natural clay, calcined clay (e.g. as prepared from kaolin, sericite, bentonite, pyrophyllite, montmorillonite, or talc at 200 to 1,000‹C), or pulverised cellulose or corn starch, having a diameter of 0.1 to 10Á. The powder is mixed with a dispersion or solution of organopolysiloxane, before drying, and crosslinking if necessary, to form completely or partially coated powder particles. The organopolysiloxane may be A an crosslinkable addition polymer of an organopolysiloxane having a vinyl group and an organohydrogenpolysiloxane, B silicone varnishes, C condensation product of (a) organohydroxysiloxane units, (b) organohydroxysiloxane and organohydrogensiloxane units and (c) organohydroxysiloxane and alkoxysiloxane. The silicone varnishes may be modified by alkyd, acrylate, polyester, phenol, melamine, or urethane resin. The Examples disclose many suitable particular binders and polysiloxanes.