CPC C09J 183/04 (2013.01) [C08K 5/5419 (2013.01); C08K 5/5425 (2013.01); C09J 7/38 (2018.01); C08G 77/12 (2013.01); C08G 77/20 (2013.01)] | 15 Claims |
1. A silicone pressure sensitive adhesive composition comprising:
(A) an aliphatically unsaturated polydiorganosiloxane component comprising
(A-1) 15 weight % to 30 weight %, based on combined weights of starting materials (A) to (F), of a polydiorganosiloxane gum of unit formula (RM2RUSiO1/2)2(RM2SiO2/2)a, where each RM is an independently selected monovalent hydrocarbon group of 1 to 30 carbon atoms that is free of aliphatic unsaturation; each RU is an independently selected monovalent aliphatically unsaturated hydrocarbon group of 2 to 30 carbon atoms; and subscript a has a value sufficient to give the polydiorganosiloxane gum a number average molecular weight of ≥500,000 g/mol;
(A-2) 5 to 20 weight %, based on combined weights of starting materials (A) to (F), of a polydiorganosiloxane polymer of unit formula (RM2RUSiO1/2)x(RM3SiO1/2)y(RMRUSiO2/2)z(RM2SiO2/2)w, where x≥0, y≥0, (x+y)=2, z>0, and w≥0, a quantity (x+z)>0, and a quantity (x+y+z+w) is sufficient to give the polydiorganosiloxane polymer a number average molecular weight of 10,000 to 300,000 g/mol,
(B) 50 weight % to 70 weight %, based on combined weights of starting materials (A) to (F), of a polyorganosilicate resin component comprising
(B-1) a capped resin of unit formula: (RM3SiO1/2)z(SiO4/2)oZp, where Z is a hydrolyzable group, subscript p is 0 to a value sufficient to give the capped resin a hydrolyzable group content up to 2 mole %, subscripts z and o have values such that z>4, o>1, and a quantity (z+o) has a value sufficient to provide the capped resin with a number average molecular weight of 500 g/mol to 5,000 g/mol;
(B-2) an uncapped resin of unit formula (RM3SiO1/2)z′(SiO4/2)o′Zp′, where subscript p′ has a value sufficient to give the uncapped resin a hydrolyzable group content of >3 mole % to 10 mole %, subscripts z′ and o′ have values such that z′>4, o′>1, and a quantity (z′+o′) has a value sufficient to provide the uncapped resin with a number average molecular weight of 500 g/mol to 5,000 g/mol,
where starting materials (B-1) and (B-2) are present in a weight ratio (B-2):(B-1) of 0.3:1 to 6:1;
where starting materials (A) and (B) are present in a weight ratio of (B):(A) (Resin:Polymer ratio)>1.6:1;
(C) 0.01 weight % to 5 weight %, based on combined weights of starting materials (A) to (F) of a hydrosilylation reaction catalyst;
(D) 0.1 weight % to 5 weight %, based on combined weights of starting materials (A) to (F) of a polyorganohydrogensiloxane of unit formula: (RM3SiO1/2)2(RM2SiO2/2)e(HRM2SiO2/2)f, where subscript e 0, subscript f≥3 and a quantity (e+f) is 4 to 500;
where starting materials (A), (B), and (D) are present in amounts such that molar ratio of silicon bonded hydrogen atoms in starting material (D) to aliphatically unsaturated groups in starting materials (A) and (B) (SiH/Vi ratio) is 3 to 50;
(E) 0.1 weight % to 5 weight %, based on combined weights of starting materials (A) to (F), of an anchorage additive;
(F) 0 weight % to 5 weight %, based on combined weights of starting materials (A) to (F) of a hydrosilylation reaction inhibitor; and
(G) 0 weight % to 60 weight %, based on combined weights of all starting materials in the composition of a solvent,
with the proviso that the silicone pressure sensitive composition is free of fluorinated starting materials.
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