GB902142A - Process for depositing a metallised surface on an article - Google Patents

Abstract

A article is metallized by forming a layer of metal powder and a resinous material which passes slowly through a gelled condition during a room temperature curing cycle, exposing the metal powder when the medium is further cured, and depositing a metal layer on the exposed metal particles. The metal particles may be of spherical form and their size may be up to 5 microns. The mixture may be applied as a thin layer on a former or mould surface which may be pre-treated to ensure adherence of the resin, or the surface may be treated with a release agent so that the resin mixture layer may be removed therefrom. In the latter case, a support may be applied to the mixture while in gelled condition so that union is effected. Finely divided silica powder may be added to increase the electrical resistance. The resin may be a polyester, epoxy, or polyvinyl resin, and may contain cobalt naphthenate, methyl ethyl ketone peroxide, and an amine derivative. In Example 1, an aluminium plate coated with a silicone release agent is coated with a mixture consisting of polyestervinyl resin, flexible polyester-vinyl resin, iron powder, cobalt naphthenate, and methyl ethyl ketone peroxide, and, after gelling, a laminate of six layers of glass cloth impregnated with polyester resin, cobalt naphthenate, and methyl ethyl ketone peroxide. After curing, the laminate is removed and the iron-resin surface abraded, washed and immersed in acidified copper sulphate solution to effect copper plating. In Example 2, a glass fibre-polyester resin sheet coated with a polyester resin-iron powder mixture is abraded, washed and treated in an aqueous solution of nickel chloride, sodium hypophosphite and sodium glycollate to effect nickel plating. In Example 3, a glass fibre-polyester resin sheet is coated with a polyester-vinyl resincobalt powder mixture and, after abrasion, is copper plated. In Example 4, nickel powder is used, and gold plating effected by immersion in an acidified bath of gold potassium chloride. In Example 5, a semi-cylindrical plastic mould is coated with an aqueous sodium alginate parting agent and then with a polyester-vinyl resin, iron powder, and silica powder mixture. Three layers of glass cloth impregnated with uncured polyester resin are applied, and then a glass fibre honeycomb impregnated with polyester resin is applied and temporarily tied in position. A glass cloth impregnated with a polyester-vinyl resin composition containing silica powder is applied, and then further layers of the impregnated glass cloth. The whole is temporarily covered with "Cellophane" (Registered Trade Mark) and removed from the mould after curing. After abrasion, a wooden trough is built up round the semi-cylindrical moulded structure and acidified copper sulphate solution poured in to effect copper plating. In Example 6, an iron powder surfaced polyester resin-glass fibre laminate is abraded, washed, dried, coated with photosensitive enamel, printed from a negative, developed to form a resist, and copper plated. In Example 7, a pressure-moulded asbestosreinforced phenolic pulg carrying lead-out wires is painted, after abrasion, with a thin film of polyester resin-iron powder mixture, and the surface and lead-out wires are abraded until a common flush surface is obtained. Photo-sensitive solution is applied and dried, and a circuit printed thereon from a negative. After development of the resist, the plug is copper plated in an acidified copper sulphate bath. In Example 8, the abraded surface of a glass fibre reinforced polyester resin laminate is coated with a polyester resin, iron powder and silica powder mixture, allowed to cure, and abraded. In Example 9, a laminate produced as in Example 1 is electroplated to increase the thickness of the copper, parts of the surface are masked, and etching is effected with ferric chloride solution. In the production of electric circuits, a resin-metal powder mixture may be applied to the whole of a surface, and after curing a thin film of water-resistant lacquer is applied. After exposure of the metal powder by abrasion in the lines of the circuit, the lines are plated. Alternatively, the mixture may be printed in the desired pattern by the silk screen process and then treated uniformly, or the circuit pattern may be formed by photographic means. Several composite layers each comprising a support, a resin-metal powder mixture, and a plated layer may be used. The articles formed may include conducting supports for articles made by electroplating or moulds, e.g. plastic moulds, provided with metal faces. According to the first Provisional Specification, the exposed metal particles may be treated with an activating agent such as a saturated solution of stannous chloride. A mixture of an epoxide resin, 4-micron size carbonyl iron powder, and triethylene tetramine may be coated on to asbestos fibre reinforced phenolic resin. The resinous material may also be polyvinyl acetate or a butyral modified phenolic resin.ALSO:An article is metallized by forming a layer of a mixture of metal powder and a resinous material which passes slowly through a gelled condition during a room temperature curing cycle, exposing the metal powder when the medium is further cured, and depositing a metal layer on the exposed metal particles. The metal particles may be of spherical form and their size may be up to 5 microns. The mixture may be applied as a thin layer on a former or mould surface which may be pretreated to ensure adherence of the resin, or the surface may be treated with a release agent so that the resin mixture layer may be removed therefrom. In the latter case, a support may be applied to the mixture while in gelled condition so that union is effected. Finely divided silica powder may be added to increase the electrical resistance. The resin may be a polyester, epoxy, or polyvinyl resin, and may contain cobalt naphthenate, methyl ethyl ketone peroxide and amine derivative. In Example 1, an aluminium plate coated with a silicone release agent is coated with a mixture consisting of polyester-vinyl resin, flexible polyester-vinyl resin, iron powder, cobalt naphthenate, and methyl ethyl ketone peroxide and, after gelling, a laminate of six layers of glass cloth impregnated with polyester resin, cobalt naphthenate, and methyl ethyl ketone peroxide. After curing, the laminate is removed and the iron-resin surface abraded, washed and immersed in acidified copper sulphate solution to effect copper plating. In Example 2, a glass fibre-polyester resin sheet coated with a polyester resin-iron powder mixture is abraded, washed and treated in an aqueous solution of nickel chloride, sodium hypophosphite and sodium glycollate to effect nickel plating. In Example 3, a glass fibre-polyester resin sheet is coated with a polyester-vinyl resin-cobalt powder mixture and, after abrasion, is copper-plated. In Example 4, nickel powder is used, and gold plating effected by immersion in an acidified bath of gold potassium chloride. In Example 5, a semi-cylindrical plastic mould is coated with an aqueous sodium alginate parting agent and then with a polyester-vinyl resin, iron powder, and silica powder mixture. Three layers of glass cloth impregnated with uncured polyester resin are applied, and then a glass fibre honeycomb impregnated with polyester resin is applied and temporarily tied in position. A glass cloth impregnated with a polyester-vinyl resin composition containing silica powder is applied, and then further layers of the impregnated glass cloth. The whole is temporarily covered with "Cellophane" (Registered Trade Mark), and removed from the mould after curing. After abrasion, a wooden trough is built up round the semi-cylindrical moulded structure and acidified copper sulphate solution poured in to effect copper-plating. In Example 6, an iron powder surfaced polyester resin-glass fibre laminate is abraded, washed, dried, coated with photo-sensitive enamel, printed from a negative, developed to form a resist, and copper-plated. In Example 7, a pressure-moulded asbestos-reinforced phenolic plug carrying lead-out wires is painted, after abrasion, with a thin film of polyester resin-iron powder mixture, and the surface and lead-out wires are abraded until a common flush surface is obtained. Photo-sensitive solution is applied and dried, and a circuit printed thereon from a negative. After development of the resist, the plug is copper-plated in an acidified copper sulphate bath. In Example 8, the abraded surface of a glass fibre reinforced polyester resin laminate is coated with a polyester resin, iron powder and silica powder mixture, allowed to cure, and abraded. In Example 9, a laminate produced as in Example 1 is electroplated to increase the thickness of the copper, parts of the surface are masked, and etching is effected with ferric chloride solution. In the production of electric circuits, a resin-metal powder mixture may be applied to the whole of a surface, and after curing a thin film of water-resistant lacquer is applied. After exposure of the metal powder by abrasion in the lines of the circuit, the lines are plated. Alternatively, the mixture may be printed in the desired pattern by the silk screen process and then treated uniformly, or the circuit pattern may be formed by photo-graphic means. Several composite layers each comprising a support, a resin-metal powder mixture, and a plated layer may be used. The articles formed may include conducting supports for articles made by electroplating or moulds, e.g. plastic moulds, provided with metal faces. According to the first Provisional Specification, the exposed metal particles may be treated with an activating agent such as a saturated solution of stannous chloride. A mixture of an epoxide resin, 4-micron size carbonyl iron, and triethylene tetramine may be coated on to as