GB1212536A - Improvements in or relating to bright zinc electroplating - Google Patents

Abstract

1,212,536. Electro-deposition of bright zinc. M & T CHEMICALS Inc. Nov.1, 1967 [Nov. 2, 1966], No.49714/67. Heading C7B. Bright zinc is electro-deposited from an aqueous alkaline pyrophosphate solution containing zinc ions and at least one organic carrier compound selected from (a) bis [sulphonaphthyl] methane and salts thereof, (b) other naphthalene derivatives containing as substituents radicals selected from hydroxyl and sulphonic acids and their alkali metal salts, which sulphonic acids are optionally further substituted by hydroxyl, amino or imino radicals, (c) benzene derivatives containing as substituents radicals selected from sulphonamides, sulphonic acids and their alkali metal or ammonium salts, (d) ally sulphonic acid and its alkali metal or ammonium salts; at least one carbonyl compound selected from aldehydes R CHO and ketones R<1> -CO-R<11> where R is hydrogen or an alkyl, aryl or a heterocyclic oxygen or sulphur radical and R<1> and R<11> are alkyl or aryl radicals; and at least one mono-or dicarboxylic acid R<111> (COOH)n where R<111> is a hydrocarbyl or inertly substituted hydrocarbyl group, or an anhydride of such an acid. Numerous examples are given in the spec<n>. The bis [sulphonaphthyl] methane compounds may contain up to three sulphonic acid groups on either of the naphthyl fused rings and the organic carboxylic acids may be substituted by halogen alkoxy or phenoxy groups and may include halogenated sulphobenzoic acids. Plating may be effected on to ferrous metals, copper, brass or bronze or copper coated die cast metals or non-conductive articles e.g. of plastics which have been chemically plated with silver, copper or nickel. The pyrophosphate zinc stock bath to which the organic compounds are added as brightener is typically as described in Specification 1, 083, 504 and the modified baths are employed under similar conditions to those of the prior spec<n>. Reference has been directed by the Comptroller to Specification 1, 083, 504.