Solventless or high solids-containing silicone pressure sensitive adhesive compositions

Claim 1

An organopolysiloxane composition curable to produce a pressure sensitive adhesive having high tack and high peel adhesion, comprising by weight: (A) from about 50 to about 75 parts by weight of a toluene soluble, resinous copolymer comprising R₃SiO 1/2 units and SiO 4/2 units wherein R is a monovalent hydrocarbon radical having from 1 to about 6 carbon atoms, wherein the resinous copolymer comprises from about 0.2% to about 5.0% by weight, based on the total weight of the copolymer, of hydroxyl radicals, at least 95% of all R groups being an alkyl group, the total number of R radicals that are alkenyl radicals being 0-0.5% of all R radicals, the molar ratio of R₃SiO 1/2 units to SiO 4/2 units being from about 0.6 to about 0.9 inclusive; (B) an alkenyl-terminated polydiorganosiloxane having a viscosity of from about 10 to about 500 centipoise at 25°C and having the general formula (I)   R²R¹₂SiO(R³₂SiO) m SiR¹₂R² wherein each R¹ is independently an alkyl group having from 1 to about 10 carbon atoms or an aryl group, R² is an alkenyl group having from 1 to about 10 carbon atoms, each R³ is independently R¹ or R², with the proviso that at least 99.5% of all R³ radicals are R¹, "m" is a number in the range of from about 1 to about 300; (C) a hydride-terminated organohydrogenpolysiloxane compatible with the mixture of (A) and (B) and having a viscosity of from about 10 to about 1000 centipoise at 25°C and having the general formula (II)   R⁴₂HSiO(R⁵₂SiO) a SiHR⁴₂ wherein each R⁴ is independently an alkyl group having from 1 to about 10 carbon atoms or an aryl group, and each R⁵ is hydrogen or R⁴, with the proviso that at least 99.5% of all R⁵ radicals are R⁴, "a" is a number in the range of from 1 to about 500, there being at least two silicon-bonded hydrogen atoms per molecule of (C), no silicon atom bearing more than one silicon-bonded hydrogen atom; the total of (B) and (C) being from about 25 to about 50 parts by weight; the total of (A), (B), and (C) being 100 parts by weight; the molar ratio of silicon-bonded hydrogen groups in (C) to silicon-bonded alkenyl groups in (A) and (B) being in the range of from about 1.2:1 to about 15.0:1; (D) a catalytic amount of a hydrosilation catalyst; and (E) from 0 to about 40% by weight of an organic solvent.

Claim 9

A method for preparing a pressure sensitive adhesive having high tack and high peel adhesion, comprising the step of heating to a temperature of about 135°C or higher for a period of time of from about 3 to about 5 minutes, a mixture comprising by weight: (A) from about 50 to about 75 parts by weight of a toluene soluble, resinous copolymer comprising R₃SiO 1/2 units and SiO 4/2 units wherein R is a monovalent hydrocarbon radical having from 1 to about 6 carbon atoms, wherein the resinous copolymer comprises from about 0.2% to about 5.0% by weight, based on the total weight of the copolymer, of hydroxyl radicals, at least 95% of all R groups being an alkyl group, the total number of R radicals that are alkenyl radicals being 0-0.5% of all R radicals, the molar ratio of R₃SiO 1/2 units to SiO 4/2 units being from about 0.6 to about 0.9 inclusive; (B) an alkenyl-terminated polydiorganosiloxane having a viscosity of from about 10 to about 500 centipoise at 25°C and having the general formula (I)   R²R¹₂SiO(R³₂SiO) m SiR¹₂R² wherein each R¹ is independently an alkyl group having from 1 to about 10 carbon atoms or an aryl group, R² is an alkenyl group having from 1 to about 10 carbon atoms, each R³ is independently R¹ or R², with the proviso that at least 99.5% of all R³ radicals are R¹, and "m" is a number in the range of from about 1 to about 300; (C) a hydride-terminated organohydrogenpolysiloxane compatible with the mixture of (A) and (B) and having a viscosity of from about 10 to about 1000 centipoise at 25°C and having the general formula (II)   R⁴₂HSiO(R⁵₂SiO) a SiHR⁴₂ wherein each R⁴ is independently an alkyl group having from 1 to about 10 carbon atoms or an aryl group, and each R⁵ is hydrogen or R⁴, with the proviso that at least 99.5% of all R⁵ radicals are R⁴, "a" is a number in the range of from 1 to about 500, there being at least two silicon bonded hydrogen atoms per molecule of (C), no silicon atom bearing more than one silicon bonded hydrogen atom; the total of (B) and (C) being from about 25 to about 50 parts by weight; the total of (A), (B), and (C) being 100 parts by weight; the molar ratio of silicon-bonded hydrogen groups in (C) to silicon-bonded alkenyl groups in (A) and (B) being in the range of from abouit 1.2:1 to about 15.0:1; (D) a catalytic amount of a hydrosilation catalyst; and (E) from 0 to about 40% by weight of an organic solvent.

Claim 10

A method for preparing a pressure sensitive adhesive having high tack and high peel adhesion, comprising the step of heating to a temperature of about 125°C or higher for a period of time of at least about 5 minutes, a mixture comprising by weight: (A) from about 50 to about 75 parts by weight of a toluene soluble, resinous copolymer comprising R₃SiO 1/2 units and SiO 4/2 units wherein R is a monovalent hydrocarbon radical having from 1 to about 6 carbon atoms, wherein the resinous copolymer comprises from about 0.2% to about 5.0% by weight, based on the total weight of the copolymer, of hydroxyl radicals, at least 95% of all R groups being an alkyl group, the total number of R radicals that are alkenyl radicals being 0-0.5% of all R radicals, the molar ratio of R₃SiO 1/2 units to SiO 4/2 units being from about 0.6 to about 0.9 inclusive; (B) an alkenyl-terminated polydiorganosiloxane having a viscosity of from about 10 to about 500 centipoise at 25°C and having the general formula (I)   R²R¹₂SiO(R³₂SiO) m SiR¹₂R² wherein each R¹ is independently an alkyl group having from 1 to about 10 carbon atoms or an aryl group, R² is an alkenyl group having from 1 to about 10 carbon atoms, each R³ is independently R¹ or R², with the proviso that at least 99.5% of all R³ radicals are R¹, and "m" is a number in the range of from about 1 to about 300; (C) a hydride-terminated organohydrogenpolysiloxane compatible with the mixture of (A) and (B) and having a viscosity of from about 10 to about 1000 centipoise at 25°C and having the general formula (II)   R⁴₂HSiO(R⁵₂SiO) a SiHR⁴₂ wherein each R⁴ is independently an alkyl group having from 1 to about 10 carbon atoms or an aryl group, and each R⁵ is hydrogen or R⁴, with the proviso that at least 99.5% of all R⁵ radicals are R⁴, "a" is a number in the range of from 1 to about 500, there being at least two silicon bonded hydrogen atoms per molecule of (C), no silicon atom bearing more than one silicon bonded hydrogen atom; the total of (B) and (C) being from about 25 to about 50 parts by weight; the total of (A), (B), and (C) being 100 parts by weight; the molar ratio of silicon-bonded hydrogen groups in (C) to silicon-bonded alkenyl groups in (A) and (B) being in the range of from about 1.2:1 to about 15.0:1; (D) a catalytic amount of a hydrosilation catalyst; and (E) from 0 to about 40% by weight of an organic solvent.