Method of making silicone pressure sensitive adhesives
AssigneeDow Corning Corporation
InventorsMartin Eric Cifuentes, William Neal Fenton, Bianxiao Zhong
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Abstract
The present invention relates to a method of making silicone pressure sensitive adhesive compositions comprising the steps of heating a mixture of a polydiorganosiloxane, a silicone resin copolymer, and an equilibration catalyst, and then adding an organic peroxide or azo compound to the resultant reaction product. The silicone pressure sensitive adhesives prepared by the method of this invention are useful in preparing articles such as pressure sensitive tapes, labels, emblems and other decorative or informational signs.
Claims22
A method of making a silicone pressure sensitive adhesive composition comprising the steps of:
- (I) heating a mixture comprising:
- (A) (i) a hydroxyl-terminated polydiorganosiloxane having a viscosity of from 100 to 10,000,000 nm.sup.2 /s at 25.degree. C. or
- (ii) a mixture of (a) a hydroxyl-terminated polydiorganosiloxane and (b) a polydiorganosiloxane selected from (i) polydiorganosiloxanes terminated with monovalent hydrocarbon radicals free of aliphatic unsaturation or (ii) alkenyl-terminated polydiorganosiloxanes wherein said mixture has a viscosity of from 100 to 10,000,000 mm.sup.2 /s at 25.degree. C.;
- (B) a soluble silicone resin comprising R.sub.3 SiO.sub.1/2 siloxane units and SiO.sub.4/2 units having a number average molecular weight of 3000 to 7500, wherein R is selected from a monovalent hydrocarbon or halohydrocarbon radical having from 1 to 20 carbon atoms, an alkenyl radical, or a hydroxyl radical;
- and
- (C) an equilibration catalyst selected from alkali metal oxides, alkali metal alkoxides, alkali metal hydroxides, alkali metal silanolates, alkali metal siloxanolates, alkali metal amides, or alkyl metals to form a reaction product having a solids content of at least 80% and a viscosity of up to 200,000 millipascal-seconds;
- and
- (II) adding (D) an organic peroxide or azo compound to the reaction product of (I).
Dependencies are inferred from the claim text.