GB1479658A - Polyurethane foams - Google Patents

Abstract

1479658 Polyurethane foams IMPERIAL CHEMICAL INDUSTRIES Ltd 2 April 1975 [24 April 1974] 18085/74 Headings C3R and C3C A flexible polyurethane foam is prepared by reacting a diphenylmethane diisocyanate composition containing at least 15% wt. of 2,4<SP>1</SP>- diphenylmethane diisocyanate with a modified polyether polyol prepared by the free radical polymerization of one or more ethylenically unsaturated monomers in situ in a polyether polyol having a molecular weight of from 1000 to 10,000, the amount of monomer(s) used generally being from 1-75% wt. based on the weight of the polyol. The modified polyether polyols are believed to be dispersions of polymers and copolymers of ethylenically unsaturated monomers in unchanged polyether polyol together with various graft copolymers formed by the grafting of polymer and copolymer chains of ethylenically unsaturated monomers on to the polyether polyol. Suitable polyols are obtained by the reaction of alkylene oxides or substituted alkylene oxides with a compound containing a plurality of active hydrogen atoms and are preferably polyoxypropylene and poly- (oxypropylene-oxyethylene) diols and triols. The modified polyether polyol may be used in admixture with unmodified polyether polyols or polyester polyols. Suitable monomers include styrene, α-methylstyrene, ethers and esters of vinyl achohol, acrylonitrile, methacrylonitrile, esters of acrylic and methacrylic acid and mixtures thereof. The preferred diphenylmethane diisocyanate composition contains 20-80% wt. of the 2,41-isomer, the remainder being the 4,4<SP>1</SP>-isomer with small amounts of the 2,2<SP>1</SP>- isomer. Other isocyanates, e.g. tolylene diisocyanate may additionally be present in the reaction mixture, as well as conventional ingredients such as blowing agents, catalysts, surfactants, crosslinkers, flame-retardants and fillers. The density of the foam may be modified by overpacking. In the examples flexible foams are prepared from a formulation comprising pure diphenylmethane diisocyanate containing 60% wt. of the 2,4<SP>1</SP>-isomer and 40% wt. of the 4,4<SP>1</SP>-isomer, a silicone surfactant, stannous octoate, bis(dimethylaminopropyl)urea, water, and a modified polyether polyol mixture which has been prepared either (1) by polymerizing a 50/50 wt. mixture of acrylonitrile and methylmethacrylate in the presence of an ethylene oxide tipped polyoxypropylene diol of M. Wt. 3500, and mixing the product with an equal weight of an equimolar mixture of an ethylene oxide tipped oxypropylated glycerol (M. Wt. 6000) and an ethylene oxide tipped oxypropylated diethylene glycol (M. Wt. 4000); or (2) by polymerizing acrylonitrile and methylmethacrylate (50/50 mixture) in the presence of an ethylene oxide tipped oxypropylated glycerol (M. Wt. 5300), the polymerization in each case being carried out in the presence of azobisisobutyronitrile as catalyst.