GB1318247A - Metallisation of shaped plastics articles - Google Patents

Abstract

1318247 Sensitizing and plating plastics; electro-plating DYNAMIT NOBEL AG 1 Sept 1970 [1 Sept 1969] 41860/70 Headings C7B and C7F Thermoplastic plastics material is sensitized by immersion in a sensitizing bath comprising an acid solution of trivalent As or Sb, activated, plated by chemical reduction and thereafter electroplated. The sensitizing bath may be a solution in HCl, H 2 SO 4 or HNO 3 , of a halide, sulphate, nitrate oxychloride, oxynitrate, carbonate or oxide of As or Sb, and is preferably As 2 O 3 and/or Sb 2 O 3 in HCl. The bath preferably contains a hydrolysable tetravalent Sn compound, e.g. Sn Cl 4 , as a wetting agent, and also a soluble halide or nitrate of NH 4 , an alkali metal and/or an alkaline earth metal as a stabilizer. Preferred amounts are 0À5-40g/l of As or Sb compound (calculated as oxide), 2-200g/l of Sn compound (as SnCl 4 ) and 10-300 g/l stabilizer; the bath is used at room temperature. The substrate may be a polymer or co-polymer of vinyl chloride, chlorinated polyethylene, a polyolefin, polyester, ABS, a filled polypropylene, polysulphone, polyacetal, polyamide or a mixture thereof, and may be pickled in chromosulphuric acid prior to sensitizing in the above bath. After sensitizing, activation is in a Pd salt solution, e.g. PdCl 2 or PdSO 4 in HCl or H 2 SO 4 at pH 1-3; this is followed by electroless plating with Cu or Ni, in turn followed by electroplating with one or more of Ag, Cu, Au, Ni or Cr. The plastics may be mounted in a holder which can serve as an electrode for electro-deposition, and carried through the whole process in that holder, which is not itself plated, and which may later be washed with oxidizing acid, e.g. chromosulphuric or HNO 3 , for re-use.