MOULD RELEASE COMPOSITION

摘要

1461538 Organopolysiloxane compositions SWS SILICONES CORP 14 May 1974 [14 May 1973] 21253/74 Heading C3T A composition comprises (i) an organopolysiloxane fluid of the general formula wherein R denotes a C 1 -C 18 monovalent hydrocarbon or halogenated hydrocarbon radical and n is greater than 20; and (ii) an aminofunctional silicon compound prepared by equilibrating a mixture of an organopolysiloxane and an aminofunctional silane or siloxane in the presence of a basic catalyst. Component (i) is preferably free of terminal hydroxyl groups, and generally has an R/Si ratio of from 1À75 to 2À25 and preferably has a viscosity of from 5-106 cSt at 25‹ C., and is preferably a polydimethylsiloxane. Component (ii) is preferably prepared from a cyclic organopolysiloxane of the general formula where w = 3-10, or a linear or branched organopolysiloxane of the average unit formula where y=0À5-2À49, z=0À001-1 and y+z= 1- 2À5, and an amino functional silane or siloxane of the formula wherein G is a radical of the formula Q denotes a radical of the formula Z is R1O 0À5 , R 3 SiO 0À5 or R1 2 NR2O 0À5 , R1 is a hydrogen atom or a C 1 -C 18 monovalent hydrocarbon radical, R2 is a saturated or unsaturated, substituted or unsubstituted C 1 - C 18 divalent hydrocarbon radical, or a substituted or unsubstituted divalent hydrocarbonoxy radical in which the oxygen is in the form of an ether linkage, a = 0-2; b = 0-3; x = 1-20,000. The composition may optionally comprise an organic solvent. The compositions can be used as mould releasing agents particularly between a metal mould and a cured polyurethane. In typical examples compositions are prepared comprising (i) 85 p.b.w. of a trimethylsilyl end-blocked polydimethylsiloxane (350 cSt), and (ii) 15 p.b.w. of an aminofunctional silicon compound prepared by heating either (a) a mixture of octamethylcyclotetrasiloxane, # - (aminoethyl) - 8 - aminorpropyltrimethoxysilane, and potassium naphthalene as catalyst, or (b) a mixture of #-(aminoethoxy) propyltrimethoxysilane, hexamethylcyclotrisiloxane and n-butyl lithium as catalyst. The compositions are applied to the surface of a metal mould and a polyurethane foam or rigid polyurethane prepared therein.