GB998232A - Siloxane pressure-sensitive adhesive composition - Google Patents

Abstract

Pressure-sensitive adhesives are prepared by a process which comprises heating a mixture of (1) 45 to 75 parts by weight of a benzene-soluble resin copolymer of SiO2 units and R3SiO1/2 units where each R is a methyl, ethyl, propyl or vinyl radical and the ratio of R3SiO1/2 units to SiO2 units is from 0.6 : 1 to 0.9 : 1, (2) 25 to 55 parts by weight of a hydroxyl terminated diorganopolysiloxane liquid of from 100 to 100,000 cs. viscosity at 25 DEG C., wherein each organic radical is a methyl, ethyl, phenyl or vinyl radical, but in which not more than 20% of the silicon atoms carry a phenyl substituent, and (3) 0.001 to 5 parts by weight of at least one of primary amine, secondary amine, tertiary amine, or carboxylic acid salt of an amine, or quaternary ammonium salt, at a temperature above 100 DEG C. until the desired adhesive character is obtained. Amines specified are diethylamine, diethanolamine, ethylamylamine, propylhexylamine, hexylamine, butanolamine, butylamine, trimethylamine, tributylamine, methyldipropylamine, tripropanolamine, methylpropylhexylamine, tetramethylammonium acetate, methylethyldibutylammonium chloride, dioctadecyldimethylammonium chloride, diethylammonium acetate, butylammonium octoate, trimethylammonium laurate, ethylnonylamine, methylpropyloctadecylamine, triethylamine, diethylpropylamine, octadecylamine, dibutylamine, dihexylammonium octoate and triethanolamine. A solvent such as xylene may be present to facilitate the mixing but is removed during the heating. The adhesive products are soluble in perchloroethylene, naphtha, toluene and trichloromonofluoromethane, and may be used in aerosol compositions dissolved in the propellant. Specifications 740,573 and 767,797 are referred to.ALSO:Pressure-sensitive adhesives prepared by heating a mixture of (1) a benzene-soluble resin copolymer of SiO2 units and R3SiO 1/2 units where each R is a methyl, ethyl, propyl or vinyl radical and the ratio of R3SiO 1/2 units to SiO2 units is 0,6 : 1 to 0,9 : 1, (2) a hydroxyl-terminated diorganopolysiloxane liquid of 100 to 100,000 cs. viscosity at 25 DEG C. wherein each organic radical is a methyl, ethyl, phenyl or vinyl radical, not more than 20% of the silicon atoms being phenyl substituted, and (3) at least one amine, carboxylic acid salt of an amine or quaternary amine salt, at a temperature above 100 DEG C., are applied in solution to substrates by spraying or brushing. Solvents specified are perchlorethylene, naphtha, toluene, mineral spirits and trichlorofluoromethane. Substrates specified are paper, cloth, glass cloth (e.g. as tape), silicone rubber, silicone resin coated glass cloth, polyethylene, polyethylene terephthalate, polytetrafluoroethylene, glass, wood and steel.