GB973303A - An improved pressure-sensitive adhesive product - Google Patents

Abstract

A pressure-sensitive adhesive product comprises a thermally stable, flexible, heat-resistant backing formed of a material selected from Fiberglas cloth, metal foils and polyester films, a first layer adherently formed upon said backing in surface engagement therewith from the heat-cured product of a first formulation containing a silicone elastomer formed of a mixture of methyl, phenyl and methyl phenyl polysiloxanes with sufficient cross linkages to impart elastomeric properties when cured, a filler as an essential ingredient and a curing agent which is a peroxide or a mixture of peroxide and tri-n-butylamine, and a second layer adherently formed upon the first layer in surface engagement therewith consisting of the normally tacky pressure-sensitive heat-cured adhesive product of a second formulation containing a silicone elastomer formed of a mixture of methyl, phenyl and methyl phenyl polysiloxanes having sufficient cross linkages to impart elastomeric properties when cured, and tri-n-butylamine as the curing agent of the second formulation. The tri-n-butylamine may be present in the second layer in an amount from 0,5 to 5 parts by weight per 100 parts by weight of the elastomer in the second layer. The filler may be present in the first layer in an amount up to 30 parts by weight per 100 parts by weight of the silicone elastomer in the first layer. The peroxide curing agent in the first layer may be present in an amount of 0,5 to 5 parts by weight per 100 parts by weight of the silicone elastomer in the first layer. The filler is selected from titanium dioxide, hydrated alumina, zinc oxide, silicon oxide, asbestos, and calcium carbonate. The peroxide curing agent in the first layer is selected from benzoyl peroxide, 2,4-dichloro benzoyl peroxide and tertiary butyl perbenzoate. The coating compositions contain sufficient inert diluent to render them workable for coating. The product may be produced by successively coating the backing with the first and second formulations, heating the first coating to displace the diluent and dry the coating and then heating the second coating to displace the diluent and dry the coating, and then heating the composite to a temperature in excess of 350 DEG F. to cure the silicone elastomers. The coatings may be applied by knife, brush or roller coating and other known methods.