Patent GB-1332139-A (GB)
Title: Electrostatic recording material and method for preparing  the same
Inventor: AKIYAMA T
IPC: G03G5/00
Filed: 1970-11-04
Abstract: 1332139 Coated electrostatic recording material JAPAN SYNTHETIC RUBBER CO Ltd and KANZAKI PAPER MFG CO Ltd 4 Nov 1970 [15 Nov 1969 28 May 1970] 52543/70 Heading B2E An electrostatic recording material is produced by coating a surface of a base sheet with an aqueous dispersion comprising: A) 100 parts by weight of at least one water insoluble polymer prepared solely from at least one monomer chosen from ethylenic monomers and conjugated diolefinic monomers, the ethylenic monomers being chosen from linear and branched defines, aromatic vinyl compounds, vinyl cyanide compounds, alkylacrylates, alkyl methacrylates, vinyl ethers, vinyl halides, and B) 1-200 parts by weight of at least one water soluble salt of a polymer containing carboxyl groups, and drying the coated product to form an electric chargeretentive layer. The base sheet may be paper, plastics sheet or metal plate. A paper base sheet may be treated with conductive material, e.g. by impregnating or coating with inorganic salts, carbon black, fine powders of aluminium, copper, nickel, polymeric electrolytes such as vinylbenzyl quaternary ammonium salt, sodium alginate, sodium polyacrylate, sodium polymethylene sulphonate. Examples of ethylenic monomers are: ethylene, propylene, butylene, styrene, vinyl toluene, halogen-substituted styrene, acrylonitrile, mathacrylonitrile, alkylacrylates and methacrylates, vinyl ethers and vinyl halides. The conjugated diolefinic monomer may be butadiene, isoprene, chloroprene, piperylene. The water-soluble salt of a polymer may be ammonium or organic amine salts of copolymers of, e.g. ethylene, styrene, vinyl toluene, acrylonitrile, methacrylonitrile, acrylate, methacrylate, vinyl halide, acrylamide, methacrylamide, halogen-substituted styrenes, vinyl ethers with unsaturated carboxylic acids such as acrylic, methacrylic, crotonic, itaconic, maleic, fumaric acid; ammonium or organic amine salts of copolymers of, e.g. butadiene, isoprene, piperylene, chloroprene, cyclopentadiene with said unsaturated carboxylic acids; and ammonium or organic amine salts of copolymers of said ethylenic monomers, said conjugated diolefins and said unsaturated carboxylic acids. A portion of the water-soluble salts of polymers may comprise ammonium or organic amine salts of complete or partial saponificates of polymers or copolymers of unsaturated carboxylic acid esters, ammonium or organic amine salts of polyesters containing free carboxyl groups, or ammonium or organic amine salts of polyamides containing free carboxyl groups. The aqueous dispersion can be prepared by: (1) polymerizing or copolymerizing at least one monomer selected from ethylenic monomers and conjugated diolefine monomers in the presence of the water soluble salts of polymer and, if necessary, an emulsifier selected from non-ionic and anionic emulsifiers; (2) adding the water-soluble salts of polymer after the polymerization or copolymerization in the presence of the emulsifier to the resulting polymers or copolymers; (3) adding the emulsifier after the polymerization or copolymerization in the presence of the water soluble salts of polymer to the resulting polymers or copolymers; or (4) by polymerizing or copolymerizing the monomers by solution polymerization and emulsifying or dispersing the resulting polymers or copolymers by means of the water-soluble salts of polymer and if necessary the emulsifier into an oil-in-water type emulsion. Examples of emulsifiers are given. The aqueous dispersion may also comprise inorganic and/or organic powder such as clay, titanium oxide, lake, zinc oxide, calcium carbonate, barium sulphate, starch, polyethylene, polystyrene, polyvinylidene chloride, a thickener such as polyvinyl alcohol, carboxy methyl cellulose, gum arabic, dyestuffs, de-foaming agents. The aqueous dispersion may be applied by air knife, roll, blade coater. In an Example an aqueous ammoniacal dispersion of polymers having a solids content of 40% was prepared by polymerizing 100 parts of a monomer mixture consisting of 20% of butadiene and 80% of styrene in the presence of 10 parts of a watersoluble ammonium salt of a terpolymer containing 30% of butadiene, 55% of methylmethacrylate and 15% of methacrylic acid and two parts of polyoxyethylene lauryl ether. The resulting dispersion was coated on to paper which had been impregnated with polyvinyl benzyl-trimethyl ammonium chloride by an air knife coater.