Patent GB-807913-A (GB)
Title: Improvements in or relating to the coating of metal surfaces
IPC: C09D101/18
Filed: 1955-05-31
Abstract: A process of refinishing a metal article which is to have a methyl methacrylate top coat and which has an area of exposed bare metal or an area coated with primer of insufficient film thickness, comprises applying to the exposed area a liquid coating composition containing (a) an organic film-forming material which contains 5-70 per cent, preferably 25-50 per cent, of lacquer grade nitrocellulose, 5-75 per cent, preferably 20-55 per cent, of shellac, 3-40 per cent, preferably 3-20 per cent, of polyvinyl butyral resin, and 0-50 per cent, preferably 10-40 per cent, of a plasticizer, (b) a pigment in an amount of 10-180 per cent of the total organic film-forming material present; and (c) solvent for the organic film-forming material.  The composition is then dried, and the methyl methacrylate lacquer is applied over it and allowed to dry.  The plasticizers may be any of the conventional esters normally so used, for example, dibutyl phthalate, phthalyl esters of glycolic acid, phthalic acid diesters of glycol ethers, toluene ethyl sulphonamide, glycol sebacate, polyethylene glycol sebacate and tricresyl or triphenyl phosphate.  The pigments suitable for use include any of the conventional pigments, for example, titanium dioxide, iron oxide, zinc chromate, iron blue, carbon black, hydrated chromium oxide, barytes, whiting, talc, china clay, phthalocyanines and organic maroons.  The lacquer solvents may be the acetic acid esters of the lower alcohols, glycols and glycol ethers, the lower ketones and alcohols, and such hydrocarbons as toluene, xylene and naphtha. Specifications 763,158, 807,895, [both in Group IV (a)], and 807,912 are referred to.ALSO:A nitrocellulose lacquer, principally of use as a repair primer for coating metal which is later to be coated with a methyl methacrylate lacquer topcoat, comprises (a) an organic film-forming material containing 5-70 per cent, preferably 25-50 per cent, of lacquer-grade nitrocellulose, 5-75 per cent, preferably 20-55 per cent, of shellac, 3-40 per cent, preferably 3-20 per cent, of polyvinyl butyral resin, and 0-50 per cent, preferably 10-40 per cent, of a plasticizer; (b) a pigment in an amount of 10-180 per cent of the total organic film-forming material present; and (c) a solvent for the organic film forming material.  The plasticizers may be any of the conventional esters normally so used, for example, dibutyl phthalate, phthalyl esters of glycolic acid, phthalic acid diesters of glycol ethers, toluene ethyl sulphonamide, glycol sebacate, polyethylene glycol sebacate, and tricresyl or triphenyl phosphate. The pigments suitable for use include any of the conventional pigments, for example, titanium dioxide, iron oxide, zinc chromate, iron blue, carbon black, hydrated chromium oxide, barytes, whiting, talc, china clay, phthalocyanines and organic maroons.  The lacquer solvents may be the acetic acid esters of the lower alcohols, glycols and glycol ethers, the lower ketones and alcohols, and such hydrocarbons as toluene, xylene and naphtha.  The method of using such priming compositions is described in some detail. Specifications 763,158, 807,895 and 807,912, [Group III], are referred to.