Patent GB-1413696-A (GB)
Title: Protective coating for activated substrates
IPC: C23C18/30
Filed: 1973-12-06
Abstract: 1413696 Protecting active surfaces KOLL MORGEN CORP 6 Dec 1973 [13 Dec 1972] 56621/73 Heading B2E [Also in Division C7] An article comprising a porous wettable surface having active bonding sites for electroless metal deposition, is coated with a protective coating comprising a film-forming material which is strippable from the surface, the filmforming material being selected from polyacrylamide, poly(acrylic or methacrylic) acid, or esters, methyl cellulose, hydroxy-ethyl cellulose, polyvinyl alcohol, polyethylene oxide, polyethylene glycol, gelatin, casein, polyvinyl pyrrolidone, methyl vinyl ether-maleic anhydride copolymer or carboxymethyl cellulose. After stripping the surface is treated with a conventional electroless metal coating solution. The film-forming material may be applied from solution or when molten. Suitable substrates include moulded and laminated plastics articles resin-coated articles and ceramics treated to make the surface porous. The interior of a fluidised bed resin-coated substrate may be a metal such as Al, Fe or Cu, or may be paper, cardboard, cloth, glass, porcelain or steatite (a ceramic). The resin of a moulded substrate may be natural rubber, rosin, amber, celluloid, optionally modified polystyrene, ABS resin, cellulose acetate, nylon, epoxy, polyester, phenolic, P.T.F.E., polyethylene, polypropylene, butyl rubber, polycarbonates, polyphenylene ethers or polysulphones. Others mentioned are p.v.c., polyurethane, polymethylmethacrylates, or styrene acrylonitrile copolymers alone or mixed with ABS resin. Further substrates include phenolic resin/paper, epoxy resin/paper, epoxy resin/fibre glass, or polyester resin/fibre glass, coated with epoxy, phenolic, or a nitrile rubber resin, optionally containing particles of an oxidisable rubber. The oxidisable rubber particles are treated with permanganate solution to provide the active bonding sites. The substrate may have a surface of phenolic, epoxy, melamine, acrylic, polyester, natural rubber or polystyrene resin applied by transfer of partially cured resin. Resin surfaces may be rendered porous by solvent treatment, and may be activated by oxidation with permanganate or by sequential treatment with (a) stannous ions, then (b) a solution of Pd or Pt ions. The substrate may also be made catalytic towards the electroless deposition by dispersing throughout it catalytic fillers. In examples (1) an ABS resin car radiator grille is activated, coated by dipping in polyethylene glycol solution, which may be stripped by dipping in hot water before coating with Cu by electroless deposition, (2) the same procedure as (1) is followed with various preferred strippable polymers, (3) polymethyl methacrylate is used instead of the polyethylene glycol of ex. 1, and may be stripped by dissolving in an organic solvent (4) an epoxy resin/glass laminate is activated and coated with polyethylene glycol which may be stripped by hot water before electrocoating with Cu, (5) phenol-formalde/paper board was activated coated with polyethylene glycol, which was stripped by water before Cu-coating, (6) to form the substrate, release paper was coated with a composition including silica, phenolic and epoxy resins, nitrile rubber in liquid form and in solid lumps, the composition then being transfer coated onto a phenolic-paper or glass epoxy prepreg sheet; the substrate was then activated, coated with polyethylene glycol which was stripped before coating with Cu, (7) a bisphenol A-epichlorohydrin epoxy resin having particulate Al 2 (SiO 3 ) 3  catalyst dispersed therein was impregnated into a glass cloth, before activation, coating and stripping.