Highly stretchable adhesive silicone compositions and uses thereof as sealing/bonding agents

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.