Patent ID: 11884847
Assignee: ELKEM SILICONES USA CORP.
Field: Macromolecular chemistry, polymers (Chemistry)
Classification: CPC C  B | IPC B  C

Claim 0:
1. A curable silicone composition X comprising:
A) at least one alkenyl group-containing organopolysiloxane A having at least two silicon-bonded C2 to C20 alkenyl groups per molecule,
(B) at least one diorganohydrogensiloxy-terminated diorganopolysiloxane chain extender CE,
(C) at least one diorganoalkenylsiloxy-terminated diorganopolysiloxane gum crosslinker Alk-XL containing at least 3 silicon-bonded C2 to C20 alkenyl groups per molecule,
(D) optionally, at least one organosilicon crosslinker H-XL containing at least 3 silicon-bonded hydrogen atoms per molecule,
(E) at least one addition reaction catalyst C,
(F) at least one reinforcing mineral filler F1,
(G) optionally, at least one complementary filler F2,
(H) optionally, at least one cure rate modifier G,
(I) optionally, at least one rheology modifier H,
(J) optionally, at least one adhesion promoter I, and
(K) optionally, at least one functional additive for conferring specific properties J;
wherein the at least one diorganoalkenylsiloxy-terminated diorganopolysiloxane gum crosslinker Alk-XL containing at least 3 silicon-bonded C2 to C20 alkenyl groups per molecule has a total alkenyl content of from 0.02 to 0.10 weight %; and
wherein the amounts of the alkenyl group-containing organopolysiloxane A, the diorganohydrogensiloxy-terminated diorganopolysiloxane CE, the diorganohydrogensiloxy-terminated diorganopolysiloxane gum crosslinker Alk-XL, and the optional organosilicon crosslinker H-XL are determined such that:
1) The value of the ratio RHalk is 1.05<RHalk<1.40, wherein RHalk=nH/tAlk, and wherein:
a) nH is the number of moles of hydrogen atom directly bonded to a silicon atom in the curable silicone composition X; and
b) tAlk is the number of moles of alkenyl groups directly bonded to a silicon atom in the curable silicone composition X,

2) the % molar ratio RHCE is within the range of 90%≤RHCE≤100%, wherein RHCE=nHCE/(nHCE+nHXL)×100, and wherein:
a) nHCE is the number of moles of hydrogen atom directly bonded to a silicon atom in the diorganohydrogensiloxy-terminated diorganopolysiloxane CE, and
b) nHXL is the number of moles of hydrogen atom directly bonded to a silicon atom in the organosilicon crosslinker H-XL, and

3) the % molar ratio RAlkA is within the range of 80%≤RAlkA<95%, wherein RAlkA=(nAlkA/tAlk)×100, and wherein:
a) nAlkA is the number of moles of alkenyl groups directly bonded to a silicon atom in the organopolysiloxane A, and
b) tAlk is the number of moles of alkenyl groups directly bonded to a silicon atom in the curable silicone composition X.