Patent ID: 8143329

Claim:
A treated kaolin containing silicone rubber composition comprising: (i) one or more polymers which have the formula R 2 R 1 SiO[(R 2 SiO) x (RViSiO) y ]SiR 2 R 1 wherein each R is the same or different and is an alkyl group containing 1-6 carbon atoms, a phenyl group or a 3,3,3-trifluoroalkyl group, R 1 is a hydroxy group or an alkenyl group, x is an integer, y is zero or an integer, and x+y is between 700 and 10 000; (ii) treated kaolin (iii) a curing agent; and (iv) optional additives selected from the group of one or more rheology modifiers, pigments, colouring agents, anti-adhesive agents, plasticizers, adhesion promoters, blowing agents, fire retardants and dessicants, which composition is substantially free of reinforcing fillers; and wherein said treated kaolin comprises a kaolin treated with an alkoxysilane of the formula R (4-n) Si(OR) n wherein n has a value of 1-3; and R is an alkyl group or an aryl group.