Patent GB-888066-A (GB)
Title: Improvements in devices for stretching materials in the piece
Inventor: WILFORD ERNEST
IPC: D06C3/00
Filed: 1959-03-18
Abstract: A method of preparing urethane foams comprises reacting a material containing at least two free isocyanate groups per molcule, in the presence of a catalyst for promoting reaction of the isocyanate groups with active hydrogen atoms, a surfactant and a blowing agent, with a polyoxyalkylene polyether which is the acid catalyzed condensation product of a polyol containing from 3 to 9 hydroxyl groups per molecule condensed with from 0.5 to 3.0 molecules of an alkylene oxide per hydroxyl group of the polyol, the alkylene oxide containing at least 3 carbon atoms per molecule. Suitable polyols are glycerin, methyl glycerin, erythritol, pentaerythritol, arabitol, xylitol, sorbitol, mannitol, dulcitol, quercitol, inositol, lactositol, mono- and di-saccharides and the hexitol mixture obtained by hydrogenating invert sugar.  The polyol may contain up to 15% by weight of water.  The alkylene oxides include propylene-, 1,2- or 1,3-butylene-, isobutylene, trimethylene and butadiene oxides. Use of acid catalysts gives polymers in which about half the terminal hydroxyl groups of the alkylene ether chains are primary groups. Suitable acid catalysts are perchloric and sulphuric acids, boron halides, chlorides and bromides of aluminium, titanium and tin, and chlorides of antimony, beryllium, bismuth, cadmium, gallium, iron, uranium, zinc and zirconium, and complexes of Lewis acid catalysts with organic compounds, e.g. alcohols and ethers.  In preparing the polyurethanes the polyisocyanate may be a prepolymer obtained by reacting a polyether, polyester or polyester-amide with excess polyisocyanate, for example, 2,4-tolylene diisocyanate, metaphenylene di, isocyanate, 4-chlor-1,3-phenylene diisocyanate-4-chlor-1, 3-phenylene diisocyanate, methylene-bis-(4-phenyl-isocyanate) or 1,5-naphthylene diisocyanate). The acid-catalyzed polyethers can also be used in one-shot processes.  Suitable surfactants are organosilicones.  Catalysts specified are triethylamine, N-methylmorpholine, triethylene diamine, hexahydrodimethyl aniline, dibutyl tin dilaurate and dibutyl tin di-2-ethyl hexanoate.  Water and halogenated alkanes, e.g. CH3Cl, CHCl2F, ChClF2, CCl2F2, C2Cl2F4 are suitable blowing agents.  In examples (3) polyoxypropylene sorbitol polyethers are prepared from sorbitol and 10 moles of propylene oxide in the presence of boron trufluoride and, for comparison, NaOH.  The polyethers are converted to prepolymers by reaction with toluene diisocyanate, mixed with CCl3F, and foaming is effected by addition of a mixture of more sorbitol polyether, silicone surfactant and tetramethyl butane-diamine; (4) a boron trifluoride etherate catalysed sorbitol polyether from 5-7 moles of propylene oxide per mole of sorbitol is used, the components in the foam reaction being (A) polyether-TDI prepolymer and CCl3F and (B) polyether, CCl3F, silicone and tetramethylbutanediamine; (6) foam is prepared by a "one-shot" method from tolylene diisocyanate, polyoxypropylene (10) sorbitol, polyoxypropylene (6.3) sorbitol, silicone-glycol copolymer, tetramethylbutanediamine and CCl3F.  In other examples the polyether used is prepared from sorbitol and propylene oxide in the presence of (7) sulphuric acid, (8) boron trifluoride-phosphoric acid complex, (9) zinc chloride, (10) stannic chloride.