Ceramifiable silicone adhesives

Claim 1

A silicone adhesive composition ceramifiable to a quartz-free ceramic and suitable for adhering a plurality of greenware components together to provide a composite greenware article which can be fired to a unitary ceramic article, said composition consisting essentially of (I) a silicone pressure-sensitive adhesive consisting essentially of (A) 45 to 55 parts by weight of a polydiorganosiloxane fluid having the average formula YO(R 2 SiO) n Y wherein each R denotes, independently, a monovalent hydrocarbon radical having from 1 to 6 inclusive carbon atoms, at least 90 percent of all R radicals being methyl radicals, y denotes an endblocking radical and n has an average value so that the polydiorganosiloxane fluid has a viscosity of from 1 to 1000 pascal-seconds at 25° C., and (B) 45 to 55 parts by weight of a xylene-soluble resin copolymer consisting essentially of R 3 SiO 1/2 siloxane units and SiO 4/2 siloxane units in a mol ratio of from 0.6 to 0.9 R 3 SiO 1/2 units for each SiO 4/2 unit, wherein each R denotes, independently, a monovalent hydrocarbon radical having from 1 to 6 inclusive carbon atoms, the total of (A) plus (B) being 100 parts by weight, and (II) 100 to 400 parts by weight, for every 100 parts by weight of (A) plus (B), of a volatile-free ceramifiable filler having a softening point above 800° C. and consisting of a mixture of 55.6 percent by weight SiO 2 , 22.2 percent by weight Al 2 O 3 and 22.2 percent by weight MgO.