Patent ID: 8450442

Claim:
A borosiloxane composition, comprising: (A) a borosiloxane selected from (i) at least one polyborosiloxane having the formula (R 1 2 BO 1/2 ) l [(BO (3-v)/2 )(OH) v ] m [(R 1 BO (2-w)/2 )(OH) w ] n (R 1 3 SiO 1/2 ) p [(R 1 2 SiO (2-x)/2 ) (OH) x ] q [(R 1 SiO (3-y)/2 )(OH) y ] r [(SiO (4-z)/2 )(OH) z ] s (I), (ii) at least one borosiloxane compound having the formula R 1 a B(OSiR 1 3 ) 3-a (II), and (iii) a mixture comprising (A)(i) and (A)(ii), wherein each R 1 is independently C 1 to C 10 hydrocarbyl or C 1 to C 10 halogen-substituted hydrocarbyl, l is from 0 to 0.2, m is from 0 to 0.5, n is from 0 to 0.6, p is from 0 to 0.7, q is from 0 to 0.9, r is from 0 to 0.999, s is from 0 to 0.5, v is from 0 to 0.05, w is from 0 to 0.05, x is from 0 to 0.45, y is from 0 to 0.63, z is from 0 to 0.25, m+n is from 0.001 to 0.58, q+r+s is from 0.42 to 0.999, (p+2q+3r+4s)/(3m+2n) is from 1.01 to 1000, l+m+n+p+q+r+s≈1, wherein l, m, n, p, q, r, and s are mole fractions; wherein v, w, x, y, and z are average numbers of hydroxy groups associated with the formula and a is 0, 1, or 2, provided the borosiloxane has an average of at least two alkenyl groups per molecule; (B) an organosilicon compound having an average of at least two silicon-bonded hydrogen atoms per molecule to cure the borosiloxane; and (C) a hydrosilylation catalyst.