Addition curable silicone PSA with high lap shear strength

Claim 1

An addition curable pressure sensitive adhesive silicone composition comprising components (A), (B), (C), optionally (D), (E), and optionally (F) wherein: (A) is an aromatic soluble resin or resinous copolymer comprising R 3 SiO 1/2 units and SiO 4/2 units wherein R is a monovalent alkyl or aromatic radical having from 1 to about 6 carbon atoms, wherein the resinous copolymer comprises from about 0.2% to about 5.0% by weight, based on the total weight of copolymer, of hydroxyl radicals, the molar ratio of R 3 SiO 1/2 to SiO 4/2 being from about 0.6 to about 0.9 inclusive; (B) an alkenyl-containing polydiorganosiloxane having a viscosity of at least about 3,000 centipoise at 25° C.; (C) a set of multi-functional silicones as crosslinkers comprising: (i) a multi-functional hydride silicone having more than 2 silicon-bonded hydrogens per chain; and (ii) a multi-functional resinous alkenyl silicone having more than 2 silicon bonded alkenyl groups per chain wherein the weights of (A), (B), (C (i)), and (C (ii)) add to 100 parts by weight with (A) ranging from 50 to 75 parts per hundred parts by weight and the sum by weight of (B), (C(i)), and (C(ii)) being the balance to add to 100 parts by weight wherein the quantities of (B), (C(i)), and (C(ii) are determined by the molar ratio of silicon-bonded hydrogen (C(i)) to the molar sum of alkenyl groups in (B) and (C(ii)) being from about 1.1 to 30 and optionally (D) from 0 to about 100 parts by weight of a reaction mixture comprising from 60 to 100% by weight of component (A) and from 40 to 0% by weight of component (B) wherein the sum by weight of (A), (B), (C(i)), (C(ii)), and (D) ranges from 100 parts by weight to 200 parts by weight when the sum of (A), (B), (C(i)), and (C(ii)) is 100 parts by weight; (E) a hydrosilation catalyst; and optionally (F) an organic solvent present in the total composition from about 0 to 40% by weight based on the sum by weight of all components present whereby when said pressure sensitive adhesive silicone is cured the lap shear at 70° C. is 2.2 lbs/in 2 or greater.