Patent ID: 11859111
Assignee: DOW SILICONES CORPORATION
Field: Macromolecular chemistry, polymers (Chemistry)
Classification: CPC C | IPC C

Claim 0:
1. A silicone pressure sensitive adhesive composition comprising:
100 parts by weight of (A) a polydiorganosiloxane gum of unit formula (R13SiO1/2)a(R12R2SiO1/2)b(R12SiO2/2)c(R1R2SiO2/2)d, where each R1 is an independently selected alkyl group of 1 to 10 carbon atoms; each R2 is an independently selected alkenyl group with 2 to 10 carbon atoms; subscript a is 0, 1, or 2; subscript b is 0, 1, or 2; subscript c≥0; subscript d≥0; (c+d) has a value sufficient to provide the gum with a molecular weight ≥400,000 Da; a quantity (b+d) is sufficient to provide a silicon bonded alkenyl content of at least 0.01 weight % based on weight of the polydiorganosiloxane gum;
(B) a polyorganosilicate resin with unit formula, (R13SiO1/2)e(R12R2SiO1/2)f(SiO4/2)g(ZO1/2)h, where R1 and R2 are as described above, Z is a hydrogen atom or an alkyl group of 1 to 6 carbon atoms, subscripts e, f, g, and h represent mole fractions of each unit, e≥0, f>0, g>0, h≥0, and a quantity (e+f+g)=1;, where starting materials (A) and (B) are present in amounts sufficient to provide a molar ratio of amount of (B) to amount of (A) (Resin:Gum ratio) of 1.5:1 to 0.5:1;
(C) a polyorganohydrogensiloxane of unit formula, (R13SiO1/2)k(R12HSiO1/2)m(R1HSiO2/2)i(R12SiO2/2)j, where R1 is as alkyl group as described above, and subscripts k, m, i, and j represent numbers of each unit in the formula and have values such that k is 0, 1, or 2; m is 0, 1, or 2; a quantity (k+m)=2; i>0; and j≥0; and a quantity (i+j+k+m) is sufficient to provide the polyorganohydrogensiloxane with a degree of polymerization of 5 to 2000, where starting materials (A), (B), and (C) are present in amounts sufficient to provide a molar ratio of silicon bonded hydrogen atoms in starting material (C) to alkenyl groups in starting materials (A) and (B) of 10:1 to 50:1;
(D) an additive comprising a polydiorganocyclosiloxane selected from the group consisting of
0.18 to 8.0 parts by weight of (d1) an octaalkylcyclotetrasiloxane of unit formula (R12SiO2/2)4,
0.17 to 8.8 parts by weight of (d2) a decaaalkylcyclopentasiloxane of unit formula (R12SiO2/2)5,
0.16 to 5.0 parts by weight of (d3) a dodecaalkylcyclohexasiloxane of unit formula (R12SiO2/2)6, and
(d4) combinations of two or more of (d1), (d2), and (d3),
with the proviso that combined amounts of (d1), (d2) and (d3) is 0.91 to 17.2 parts by weight, per 100 parts by weight of starting material (A);

(E) a hydrosilylation reaction catalyst in an amount sufficient to provide 10 ppm to 7,500 ppm of platinum metal by weight based on combined weights of starting materials (A), (B), (C), (D), (E), and (F); and
0.1 to 5 parts by weight of (F) a hydrosilylation reaction catalyst inhibitor; and
(G) an organic solvent, in an amount sufficient to provide 10% to 90 weight % solvent based on combined weights of starting materials (A), (B), (C), (D), (E), (F), and (G);
with the proviso that the silicone pressure sensitive adhesive composition is free of hydroxyl-functional polydiorganosiloxane gum.