Patent ID: 7566756

Claim:
An addition curable silicone resin composition, comprising: (A) an organopolysiloxane having a resin structure comprising R 1 SiO 1.5 units, R 2 2 SiO units and R 3 a R 4 b SiO (4−a−b)/2 units wherein, R 1 , R 2 and R 3 each represent, independently, a hydroxyl group, methyl group, ethyl group, propyl group, cyclohexyl group or phenyl group, each R 4 represents, independently, a vinyl group or allyl group, a represents 0, 1 or 2, and b represents 1 or 2, provided that a+b is 2 or 3, in which at least a portion of the R 2 2 SiO units are connected in a continuous repeating sequence, and a number of units in the repeating sequence is within a range from 5 to 50, (B) an organohydrogenpolysiloxane having a resin structure comprising R 1 SiO 1.5 units, R 2 2 SiO units and R 3 c H d SiO (4−c−d)/2 units wherein, R 1 , R 2 and R 3 are as defined above, c represents 0, 1 or 2, and d represents 1 or 2, provided that c+d is 2 or 3, in which at least a portion of the R 2 2 SiO units are connected in a continuous repeating sequence, and a number of units in the repeating sequence is within a range from 5 to 50, the organohydrogenpolysiloxane provided in sufficient quantity that a molar ratio of hydrogen atoms bonded to silicon atoms within component (B) relative to a combined total of vinyl groups and allyl groups within component (A) is within a range from 0.1 to 4.0, (C) an organopolysiloxane having two or more alkenyl groups within each molecule, which is different from the component (A) and is either a liquid or a solid at 25° C., (D) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms within each molecule, which has a viscosity at 25° C. within a range from 0.5 to 50,000 mPa·s, and in a mixed state with the organopolysiloxane of component (C), has a viscosity at 25° C. within a range from 10 to 100,000 mPa·s, wherein quantities of component (C) and component (D) are sufficient that a molar ratio of a combined quantity of hydrogen atoms bonded to silicon atom within component (B) and component (D), relative to a combined quantity of alkenyl groups within component (A) and component (C), is within a range from 0.1 to 4.0, and (E) an effective curing quantity of a platinum group metal-based catalyst.