Patent GB-1484209-A (GB)
Title: Olefin resin-metal bonded structure
IPC: B32B5/18
Filed: 1975-01-31
Abstract: 1484209 Coated products TOYO SEIKAN KAISHA Ltd 31 Jan 1975 [4 Feb 1974] 4402/75 Heading B2E A structure comprises a metal substrate and an olefin resin layer bonded to the metal substrate through a primer coating consisting essentially of a first layer of a thermosetting or a thermoplastic film-forming base resin, free from oxidised polyethylene and a second layer containing oxidised polyethylene. The metal substrate may be steel, copper, aluminium, zinc, stainless steel, bronze, cupronickel, Duralumin (Trade Mark), a die-casting metal, steel-plated zinc, tin, chromium, aluminium treated with phosphoric acid or electrolytically treated with chromic acid. It may be in the form of a foil, plate, panel sheet, pipe, rod, beam, wire, twisted wire, a crown shell or other container cap, or a can or other container or vessel, or a vehicle part. A preliminary coating of a primer resin such as a phenol-epoxy resin, an epoxy-amino resin, e.g. an epoxy-urea resin, a phenol-epoxy-vinyl resin or an epoxy-vinyl resin may be present. The oxidised polyethylene preferably has an oxygen content of 0.1-10%. A part of the oxygen present may be in the form of a carboxyl group, an ether or a ketone. The degree of oxidation may be obtained from the acid value and an acid value of 2-100 is preferred. The oxidised polyethylene may have a density of 0.9 to 1.0 g/cc. The primer may also contain a phenolic resin, epoxy resin, imino resin, an oleoresinous varnish base, an alkyd resin, an acrylic resin or a vinyl resin such as a vinyl chloride-vinyl acetate copolymer, vinyl chloride, vinyl acetate-maleic acid copolymer or polyvinyl butyral. The primer may be applied as a solution in a solvent such as xylene, toluene, acetone, methylethyl ketone or methyl isobutyl ketone and may be coated in an amount 10-500 mg/dm<SP>2</SP>. The amount of oxidised polyethylene present in the primer coating may be in an amount 0.01 to 100 mg-dm<SP>2</SP>. Preferably the surface of the metal is degreased and washed. The olefin resin may be a low density, medium density or high density polyethylene, isotactic polypropylene, ethylene-butene-1 copolymer, polybutene-1, ethylene-hexene copolymer, ethylenepropylene copolymer or a copolymer of ethylene, propylene and non-conjugated diene. Other polymers may be present such as ethylene-vinyl acetate copolymer, saponified ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methyl-methacrylate copolymer, unsaturated carboxylic acid-modified polyethylenes, the carboxylic acid being, for example, maleic acid, acrylic acid or methacrylic acid or esters of these, unsaturated carboxylic acid-modified polypropylenes, ionomers, and chlorosulphonated polyethylenes. An elastomer such as an ethylene-propylene rubber, ethylene-propylene-diene rubber, polyisobutylene, butyl rubber, polybutadiene, natural rubber, stereospecific polyisoprene, nitrile rubber, styrene-propylene copolymers, or block copolymers, styrene-isoprene copolymers or block copolymers, and polychloroprene may be present. The usual additives such as antioxidants and thermal stabilisers may be present as well as lubricants, such as metallic soaps and other fatty acid derivatives, fillers such as calcium carbonate, white carbon, titanium white, magnesium carbonate, magnesium silicate, carbon black and various clays. A cross linking and/or foaming agent may also be present in the composition used to apply the olefin polymer layer.