Moldable elastomeric pressure sensitive adhesives

Claim 1

A composition for forming elastomeric pressure sensitive adhesives comprising a homogeneous mixture of: (A) a xylene-soluble resin copolymer employed in an amount from 50 to 70 parts by weight, said xylene-soluble resin copolymer consisting essentially of R 3 SiO 1/2 units and SiO 4/2 units in a mol ratio of from 0.6 to 0.9R 3 SiO 1/2 units for each SiO 4/2 unit, wherein each R denotes, independently, a monovalent hydrocarbon radical having from 1 to 6 inclusive carbon atoms, said resin copolymer having less than 0.7 weight % silicon-bonded hydroxyl units, said resin copolymer substantially free of volatile components, (B) a polydiorganosiloxane fluid employed in an amount from 30 to 50 parts by weight, said polydiorganosiloxane fluid endcapped with silicon-bonded hydroxyl groups and having the average formula HO(R' 2 SiO) n H wherein each R' denotes, independently, a monovalent hydrocarbon or halohydrocarbon radical having from 1 to 6 inclusive carbon atoms and n has an average value so that the polydiorganosiloxane fluid has a viscosity such that the elastomeric pressure sensitive adhesive composition has a plasticity of less than 150×10 -3 inches at 25° C. without the addition of organic solvents, the total of resin copolymer (A) and polydiorganosiloxane fluid (B) being 100 parts by weight, (C) an alkoxy-containing organosilicon compound having an average of more than two silicon-bonded alkoxy units per molecule employed in an amount from 0.35 to 2 parts by weight, (D) a condensation catalyst employed in an amount from 0.5 to 13 parts by weight, and (E) a trimethyl-endblocked polydimethylsiloxane employed from 0 to 15 parts by weight and having a viscosity of from 10 to 1000 cSt. at 25° C.

Claim 24

A method of forming a silicone elastomeric pressure sensitive adhesive comprising the steps of: (i) preparing an elastomeric pressure sensitive adhesive composition by (I) homogeneously mixing (A) 50 to 70 parts by weight of a xylene-soluble resin copolymer consisting essentially of R 3 SiO 1/2 units and SiO 4/2 units in a mol ratio of from 0.6 to 0.9R 3 SiO 1/2 units for each SiO 4/2 unit, wherein each R denotes, independently, a monovalent hydrocarbon radical having from 1 to 6 inclusive carbon atoms, said resin copolymer having less than 0.7 weight % silicon-bonded hydroxyl units, (B) 30 to 50 parts by weight of a polydiorganosiloxane fluid endcapped with silicon-bonded hydroxyl groups and having the average formula HO(R' 2 SiO) n H wherein each R' denotes, independently, a monovalent hydrocarbon or halohydrocarbon radical having from 1 to 6 inclusive carbon atoms and n has an average value so that the polydiorganosiloxane fluid has a viscosity such that the elastomeric pressure sensitive adhesive composition has a plasticity of less than 150×10 -3 inches at 25° C. without the addition of organic solvents, the total of resin copolymer (A) and polydiorganosiloxane fluid (B) being 100 parts by weight, (C) an alkoxy-containing organosilicon compound having an average of more than two silicon-bonded alkoxy units per molecule in an amount from 0.35 to 2 parts by weight, (D) a condensation catalyst in an amount from 0.5 to 13 parts by weight, and (E) no more than 15 parts by weight of a trimethyl-endblocked polydimethylsiloxane having a viscosity of from 10 to 1000 cSt. at 25° C., and (II) devolatilizing said resin copolymer (A) optionally in mixture with other components wherein the mixture of resin copolymer (A) with other components is substantially non-reactive at the temperature of devolatilization, (ii) placing the elastomeric pressure sensitive adhesive composition in the desired form for curing, and (iii) curing the composition which has been placed in the desired form for curing for a sufficient time to form the elastomeric pressure sensitive adhesive.

Claim 25

A method of forming a silicone elastomeric pressure sensitive adhesive comprising the steps of: (i) preparing an elastomeric pressure sensitive adhesive composition by (I) homogeneously mixing (A) 50 to 70 parts by weight of a xylene-soluble resin copolymer consisting essentially of R 3 SiO 1/2 units and SiO 4/2 units in a mol ratio of from 0.6 to 0.9R 3 SiO 1/2 units for each SiO 4/2 unit, wherein each R denotes, independently, a monovalent hydrocarbon radical having from 1 to 6 inclusive carbon atoms, said resin copolymer having less than 0.7 weight % silicon-bonded hydroxyl units, (B) 30 to 50 parts by weight of a polydiorganosiloxane fluid endcapped with silicon-bonded hydroxyl groups and having the average formula HO(R' 2 SiO) n H wherein each R' denotes, independently, a monovalent hydrocarbon or halohydrocarbon radical having from 1 to 6 inclusive carbon atoms and n has an average value so that the polydiorganosiloxane fluid has a viscosity such that the elastomeric pressure sensitive adhesive composition has a plasticity of less than 150×10 -3 inches at 25° C. without the addition of organic solvents, the total of resin copolymer (A) and polydiorganosiloxane fluid (B) being 100 parts by weight, (C) an alkoxy-containing organosilicon compound having an average of more than two silicon-bonded alkoxy units per molecule in an amount from 0.35 to 2 parts by weight, (D) a condensation catalyst in an amount from 0.5 to 13 parts by weight, and (E) no more than 15 parts by weight of a trimethyl-endblocked polydimethylsiloxane having a viscosity of from 10 to 1000 cSt. at 25° C., and (II) devolatilizing said resin copolymer (A) optionally in mixture with other components wherein the mixture of resin copolymer (A) with other components is substantially non-reactive at the temperature of devolatilization, (ii) placing the elastomeric pressure sensitive adhesive composition in the desired form for curing, and (iii) curing the composition which has been placed in the desired form for curing for a sufficient time to form the elastomeric pressure sensitive adhesive.

Claim 27

A method of forming a silicone elastomeric pressure sensitive adhesive comprising the steps of: (i) preparing an elastomeric pressure sensitive adhesive composition by (I) homogeneously mixing (A) 50 to 70 parts by weight of a xylene-soluble resin copolymer consisting essentially of R 3 SiO 1/2 units and SiO 4/2 units in a mol ratio of from 0.6 to 0.9R 3 SiO 1/2 units for each SiO 4/2 unit, wherein each R denotes, independently, a monovalent hydrocarbon radical having from 1 to 6 inclusive carbon atoms, said resin copolymer having less than 0.7 weight % silicon-bonded hydroxyl units, (B) 30 to 50 parts by weight of a polydiorganosiloxane fluid endcapped with silicon-bonded hydroxyl groups and having the average formula HO(R' 2 SiO) n H wherein each R' denotes, independently, a monovalent hydrocarbon or halohydrocarbon radical having from 1 to 6 inclusive carbon atoms and n has an average value so that the polydiorganosiloxane fluid has a viscosity of from 50 to 300,000 cP. at 25° C., the total of resin copolymer (A) and polydiorganosiloxane fluid (B) being 100 parts by weight, and (C) an alkoxy-containing organosilicon compound having an average of more than two silicon-bonded alkoxy units per molecule in an amount from 0.35 to 2 parts by weight, (D) a condensation catalyst in an amount from 0.5 to 13 parts by weight, (E) 0 to 15 parts by weight of a trimethyl-endblocked polydimethylsiloxane having a viscosity of from 10 to 1000 cSt. at 25° C., and (II) devolatilizing said resin copolymer (A) optionally in mixture with other components wherein said mixture of resin copolymer (A) with other components is substantially non-reactive at the temperature of devolatilization, (ii) placing the elastomeric pressure sensitive adhesive composition in the desired form for curing, and (iii) curing the composition which has been placed in the desired form for curing for a sufficient time to form the elastomeric pressure sensitive adhesive.

Claim 28

A method of forming a silicone elastomeric pressure sensitive adhesive comprising the steps of: (i) preparing an elastomeric pressure sensitive adhesive composition by (I) homogeneously mixing (A) 50 to 70 parts by weight of a xylene-soluble resin copolymer consisting essentially of R 3 SiO 1/2 units and SiO 4/2 units in a mol ratio of from 0.6 to 0.9R 3 SiO 1/2 units for each SiO 4/2 unit, wherein each R denotes, independently, a monovalent hydrocarbon radical having from 1 to 6 inclusive carbon atoms, said resin copolymer having less than 0.7 weight % silicon-bonded hydroxyl units, (B) 30 to 50 parts by weight of a polydiorganosiloxane fluid endcapped with silicon-bonded hydroxyl groups and having the average formula HO(R' 2 SiO) n H wherein each R' denotes, independently, a monovalent hydrocarbon or halohydrocarbon radical having from 1 to 6 inclusive carbon atoms and n has an average value so that the polydiorganosiloxane fluid has a viscosity of from 50 to 300,000 cP. at 25° C., the total of resin copolymer (A) and polydiorganosiloxane fluid (B) being 100 parts by weight, and (C) an alkoxy-containing organosilicon compound having an average of more than two silicon-bonded alkoxy units per molecule in an amount from 0.35 to 2 parts by weight, (D) a condensation catalyst in an amount from 0.5 to 13 parts by weight, (E) 0 to 15 parts by weight of a trimethyl-endblocked polydimethylsiloxane having a viscosity of from 10 to 1000 cSt. at 25° C., and (II) devolatilizing said resin copolymer (A) optionally in mixture with other components wherein said mixture of resin copolymer (A) with other components is substantially non-reactive at the temperature of devolatilization, (ii) placing the elastomeric pressure sensitive adhesive composition in the desired form for curing, and (iii) curing the composition which has been placed in the desired form for curing for a sufficient time to form the elastomeric pressure sensitive adhesive.