Patent GB-1516019-A (GB)
Title: Process for the production of polysiloxane-polyoxyalkylene copolymers
IPC: C08G81/00
Filed: 1976-12-20
Abstract: 1516019 Polysiloxane - polyoxyalkylene copolymers; polyurethane foams BAYER AG 20 Dec 1976 [24 Dec 1975] 53017/76 Headings C3T and C3R A polysiloxane-polyoxyalkylene copolymer is prepared by a process which comprises (a) reacting an organo-polysiloxane of the general formula wherein m is from 1-100, Z represents C1-C5 alkyl, C6-C15 aryl, siloxyl or siloxanyl radicals or the group -R-Y-H, R represents C1-C6 alkylene optionally containing one or more hetero atoms, Y represents -NR<1>-, -O-, -COO-, or -S-, and R<1> represents hydrogen, C1-C6 alkyl or C5-C9 cycloalkyl; with a polyisocyanate in an equivalent ratio NCO : YH# 2 : 1, (b) heating the thus-obtained NCO- containing addition product at from 110- 160 C. to cause branching generally through allophanate, biuret and/or isocyanurate groups; and (c) reacting the thus-obtained branched NCO-containing addition product generally at a temperature of from 30-150 C. with a monofunctional compound of the general formula R<11>-(OCnH2n)x-OH, wherein n is 2-4 x is 1-100, and R<1> represents a monofunctional C1-C20 hydrocarbon radical which may contain oxygen or nitrogen as hetero atoms; in an NCO : OH equivalent ratio of from 0À8 : 1 to 1À2 : 1. The resulting copolymer generally has a viscosity of from 2000 to 80,000 cP at 25 C. The polysiloxane used in step (a) preferably has a M.Wt. of from 194-20,000 and is preferably a hydroxymethyl-polysiloxane of the formula HOCH2Si(CH3)2[OSiCH3)2]n-CH2OH where n is 6-30. The polyisocyanate used in step (a) may be an aliphatic, cycloaliphatic, araliphatic or aromatic polyisocyanate preferably 2,4- and/or 2,6-tolylene diisocyanate polyphenyl-polymethylene polyisocyanates, 1,6- hexamethylene diisocyanate and 1-isocyanato- 3,3,5 - trimethyl - 5 - isocyanatomethyl cyclohexane. An acid may be added in step (a) before the reaction with the polyisocyanate. An organometallic catalyst, particularly an organotin catalyst, may be used in steps (a) and (c). After the heat-treatment in step (b) a water jet vacuum is generally applied at 150 C. The copolymer can be used as a foam stabilizer as such or as a solution in preferably watersoluble solvent, particularly a polyether, in the production of a polyurethane foam by reacting a polyisocyanate with a compound which containing NCO-reactive hydrogen atoms in the presence of a blowing agent. The stabilizers also improve the flame-proof properties of the foam. Preferred solvents for the stabilizer copolymer have the general formula wherein n is 2-4m x is 1-100, k is 2-8 and R<111> represents a k-functional Cz-C20 hydrocarbon radical. The ratio of copolymer stabilizer to solvent is generally from 2 : 1 to 1 : 4 and the viscosity of the resulting solution is generally from 1000-3000 CP at 25 C. In typical examples a copolymer stabilizer is prepared as above by reacting a mixture of W,W,-bis (hydroxymethyl)polydimethylsiloxane and ptoluene sulphonic acid methyl ester with 2,4-/ 2,6-tolylene diisocyanate, followed by a heat treatment at 150 C. and then a vacuum treatmnet, and then reacting the resulting NCO- containing prepolymer with a propylene oxide/ ethylene oxide/butanol polyether in the presence of tin (II) ethyl hexoate. The resulting copolymer is used as such or as a solution in a propylene oxide/ethylene oxide/1 3-propylene glycol polyether as a foam stabilizer in the production of a polyurethane-polyurea foam by the one shot process from the following formulation a propylene oxide/trimethylol propane/propylene glycol polyether, 2,4-/2,6-tolylene diisocyanate, triethylene diamine, tin (II) 2-ethyl caproate, water and the foam stabilizer.