GB1270611A - Process of effecting adhesion - Google Patents

Abstract

1,270,611. Adhesion of surfaces. W. R. GRACE & CO. 21 April, 1970 [21 April, 1969], No. 19112/70. Heading B5N. [Also in Divisions A4, B8 and C3] Adhesion between two surfaces is effected by interposing a composition comprising (a) a heat activatable adhesive which is a polymer or is polymerizable; and (b) particles of non- carbonaceous, non-ferromagnetic electrically conductive material consisting of or containing Al, Cu, Ag, Au or Si, the weight ratio of (b) to (a) being 5:95 to 80:20 and subjecting the assembly to a high-frequency alternating field until the adhesive is heat activated. Adhesive (a) may be polyethylene, oxidized polyethylene, ethylene/propylene or ethylene/vinyl acetate copolymer, polypropylene polystyrene, PVC, vinyl chloride/vinyl acetate copolymer, polyvinyl acetate, polyvinyl butyral, crosslinking polyesters, epoxy resin, or a phenol-, urea- or melamine-formaldehyde resin. The particles (b) should be below 1 mm. e.g. 30-200 microns and consist of the element or a non- ferromagnetic alloy thereof or inert particles coated with the element, e.g. glass beads coated with the element optionally with a resin binder. The mixture is preferably formed into sheets and cut into gasket or other form. It is used to join surfaces of polymers and particularly for sealing closures, e.g. crown caps, on plastic bottles. Frequencies of 0À5-100 megacycles/sec. are used with a power output of 0À1-30 kw. for up to 2 minutes. In examples (1) PVC containing aluminium powder and titanium dioxide is formed into discs used in a PVC closure cap on a PVC bottle; (2) polystyrene and copper powder is used to bond a pad of polystyrene filaments into a polystyrene brush handle; (3) polystyrene and copper powder is used to bond polystyrene bars together; and (4) polypropylene and aluminium powder is used to bond polypropylene bars.