GB1143571A - - Google Patents

Abstract

1,143,571. Coating. TELCON PLASTICS Ltd. 29 March, 1966 [29 Dec., 1964], No 26748/64. Heading B2E. A method of coating sub-strata with an adhesive comprises lowering the temperature of the adhesive when substantially solvent-free until it can be reduced to a fine powder, reducing it to a fine powder, and applying a sufficiently uniform layer of the powder to the substratum to ensure that, when the temperature of the adhesive is raised, the particles fuse together to form a substantially uniform coating. The adhesives are of the kind that cannot at ambient temperature be reduced to a powder and when substantially solvent free are at ambient temperature either solid or of such high viscosity that they cannot be applied by liquid coating methods without using solvent or raising the temperature e.g. heat sensitive, "hot 'melt" and solvent adhesives. The substrata may conductive or non-conductive sheet material e.g. papers, cloths, board, metal foils, plastics sheets. The adhesive may be frozen in a liquefied inert gas e.g. nitrogen and ground in an atmosphere of the gas. Active components or fillers of the adhesive may be mixed before or during grinding. The powdered adhesive may be applied by electrostatic spraying or by electrostatic coating from a fluidized bed. In the Examples (1) cloth and aluminium foil are coated with "hot melt" adhesives e.g. an adhesive containing polyisobutylene, hydrogenated rosin, polyethylene, cyclised rubber and fillers and having a "tack" point of 75 to 80‹C, pressure sensitive adhesives containing polymeric materials such as ethylene-vinyl acetate copolymers, polyvinyl ethers, polymerised alkylated styrenes, wood rosin and its derivatives, terpene resins, coumarone indene resins. The pressure sensitive, melt adhesive coating is fused using infrared heat and immediately cooled, or laminated with another material; (2) solutions of solvent adhesives such as those based on natural or synthetic rubber e.g. butyl rubber, polyisobutylene, neoprene, nitrile rubber, a resin such as wood rosin and derivatives, terpene resins, coumarone-indene resins and a softener such as mineral oil, wool fat alcohol, ester plasticizers, are free-ground after removal of solvent and applied to say a plastics sheet; (3) heat sensitive adhesives such as copolymers of vinyl chloride, acetate mixed with plasticiser e.g. tricresyl phosphate, di-2-ethylhexyphthalate, nitrocellulose mixed with raw castor oil, polyvinyl acetate mixed with triglycol di-2- ethylbutyrate as plasticiser, ethyl cellulose mixed with beeswax or hydrogenated methyl abietate, vinyl polymers with phthalate plasticizer are applied.