Patent GB-974897-A (GB)
Title: Electrically conductive protective composition
IPC: H01B1/22
Filed: 1962-02-21
Abstract: An electrically conductive coating composition comprises metal particles in a carrier which comprises (1) a copolymer of at least one monomer of the formula: <FORM:0974897/C3/1> wherein R is hydrogen or a C1-C6 alkyl radical and Z is a <FORM:0974897/C3/2> radical or a <FORM:0974897/C3/3> radical in which R1 is the same or different hydrogen atom, halogen atom or C1-C6 alkyl radical, and R2 is a C1-C20 alkyl radical, and an unsaturated carboxylic acid present in an amount of 0.25 to 5% by weight of the copolymer, and (2) an alkaline compound of a soap-forming metal, e.g. calcium, barium, strontium, magnesium and zinc hydroxides, zinc and sodium carbonates and zinc oxide. The copolymer may be made from monomers such as acrylic, methacrylic, itaconic and maleic esters, styrene and substituted styrenes, isobutylene, vinyl, allyl and isopropenyl esters, acrylonitrile, methacrylonitrile and ethacrylonitrile, together with acids such as acrylic, methacrylic, 3-butenoic, angelic, tiglic, maleic and fumaric acids. Metal particles specified are those of zinc. Also present in the compositions may be solvents, e.g. methyl isobutyl ketone, xylene, toluene, aromatic naphtha, and ethylene glycol monoethyl ether acetate; epoxy resins, e.g. reaction products of dihydroxy aromatic compounds with halogen-containing epoxy aliphatic compounds, particularly reaction products of bisphenols with epichlorohydrin; small amounts of urea-formaldehyde or melamine-formaldehyde resins; corrosion inhibitors, e.g. calcium strontium, barium, zinc and lead chromates and molybdates; and colouring matter, e.g. carbon black, zinc oxide and talc. The examples describe the preparation by solution polymerization of copolymers of: (a) styrene, 2-ethylhexyl acrylate, acrylonitrile and methacrylic acid, (b) methyl methacrylate, ethyl acrylate, acrylonitrile and methacrylic acid, and (c) styrene, 2-ethylhexyl acrylate and methacrylic acid, and the use of such copolymers in preparing coating compositions.ALSO:Steel panels are provided with an electrically conductive coating by applying thereto, e.g. by spraying, a composition comprising metal particles, e.g. zinc, in a carrier which comprises (1) an interpolymer of at least one monomer which may be an unsaturated ester or nitrile, styrene or a substituted styrene or isobutylene, and an unsaturated carboxylic acid present in an amount of 0,25-5% by weight of the interpolymer, and (2) an alkaline compound of a soap forming metal, e.g. calcium, barium, strontium, magnesium and zinc hydroxides, zinc and sodium carbonates and zinc oxide.  Also present in the compositions may be solvents, e.g. isobutyl ketone, xylene, toluene, aromatic naphtha and ethylene glycol monoethyl ether acetate; epoxy resins; aminoplasts; corrosion inhibitors, e.g. calcium, strontium, barium, zinc and lead chromates and molybdates; and colouring matter, e.g. carbon black, zinc oxide and talc.  The examples describe coating compositions comprising zinc particles, hydrated lime, solvent and copolymers of: (a) styrene, acrylonitrile, 2-ethylhexyl acrylate and methacrylic acid, (b) methyl methacrylate, ethyl acrylate, acrylonitrile and methacrylic acid, and (c) styrene, 2-ethylhexyl acrylate and methacrylic acid.