Patent GB-869459-A (GB)
Title: Copolymers suitable for use as primers
IPC: C08F220/44
Filed: 1959-11-20
Abstract: <PICT:0869459/IV (a)/1> Relates to a copolymer of monomer components consisting essentially of vinyl toluene, acrylonitrile and, optionally, acrylic or methacrylic or itaconic acid, the proportions of the monomer components on a mol equivalent basis being within the area A-C-D-F-A and preferably within the area B-C-D-F-B on the accompanying triangulation diagram, the copolymer having a relative viscosity measured at 25 DEG C. in a 1 gm./100 ml. solution in dimethyl formamide of from 1,4 to 3,5.  The vinyl toluene component may contain up to 25% of another monomer such as ethyl acrylate or methacrylate, styrene or vinyl pyridine; up to 25% of the acid component may be crotonic, maleic or fumaric acid or an acid ester such as monobutyl maleate, and methacrylonitrile may replace up to 25% of the acrylonitrile component.  The copolymers are preferably prepared by polymerization in an organic solvent such as methyl ethyl ketone or a mixture of xylol and dimethyl formamide in the presence of a free radical catalyst such as benzoyl peroxide, or azodiisobutyronitrile.  Examples describe the production of copolymers from (a) 77 parts vinyl toluene, 5 parts acrylic acid and 45 parts acrylonitrile, (b) 77 parts vinyl toluene, 5 parts acrylic acid and 30 parts acrylonitrile and (c) 77 parts vinyl toluene and 30 parts acrylonitrile.  The copolymers may be used as primers on steel prior to the application of a plastisol or organosol topcoat, the primers being applied from solution in a solvent medium such as methyl ethyl ketone, cyclohexanone, dimethyl formamide, methyl isobutyl ketone, diacetone alcohol or 2-methoxy ethanol, which may include a proportion of an aromatic solvent such as benzene, toluene or a xylene.  Other ingredients such as titanium dioxide, lead oxide and talc may be incorporated.ALSO:<PICT:0869459/III/1> A primer coating for use when bonding vinyl resin plastisols to iron or steel comprises a copolymer of monomer components consisting essentially of vinyl toluene, acrylonitrile and, optionally, acrylic or methacrylic or itaconic acid, the proportions of the monomer components on a mol equivalent basis being within the area A-C-D-F-A and preferably within the area B-C-D-F-B on the accompanying triangulation diagram, the copolymer having a relative viscosity measured at 25 DEG C. in a 1 gm./100 ml. solution in dimethyl formamide of from 1.4 to 3.5. The vinyl toluene component may contain up to 25% of another monomer such as ethyl acrylate or methacrylate, styrene or vinyl pyridine; up to 25% of the acid component may be crotonic, maleic or fumaric acid or an acid ester such as monobutyl maleate, and methacrylonitrile may replace up to 25% of the acrylonitrile component.  The primers are applied to the iron or steel, which may have been treated with phosphoric acid or galvanised, by brushing, spraying, dipping or roll coating, from solution in a solvent medium such as methyl ethyl ketone, cyclohexanone, dimethyl formamide, methyl isobutyl ketone, diacetone alcohol or 2-methoxy ethanol, which may include a proportion of an organic solvent such as benzene, toluene or a xylene.  Other ingredients such as titanium dioxide, lead oxide and talc may be incorporated. The vinyl resin plastisol coated on the primer coating may comprise polyvinyl chloride or a copolymer of vinyl chloride with a minor proportion of vinyl acetate or vinylidene chloride, and a plasticizer such as diisooctyl phthalate.