| 摘要 |
<p>Foamed polyurethanes are prepared by reacting an 80/20 mixture of tolylene 2,4 and 2,6-diisocyanates with a polyester containing more than two isocyanate-reactive groups per molecule optionally in the presence of catalysts for polyurethane foam production and water, the reaction mixture also containing a water-soluble salt of an acid ester of a polybasic acid, said acid ester containing a hydrophobic polyether chain and a polyoxyethylene ester of an aliphatic monocarboxylic acid containing 10 to 20 carbon atoms or a block copolymer of ethylene oxide and an alkylene oxide which contains at least three carbon atoms in the molecule. The polyesters may be prepared by reacting polyhydric alcohols with polycarboxylic acids one of which contains more than two reactive groups in the molecule. Suitable substances containing more than two reactive groups in the molecule are glycerol, trimethylolethane, trimethylolpropane, triethanolamine, pentaerythritol, dihydrostearic acid, trimesic acid and trimellitic acid. The acid esters can be those of hydroxyl group containing polyether products of the polymerization of cyclic oxides containing more than two carbon atoms per molecule with such acids as sulphuric and phosphoric aliphatic and aromatic polycarboxylic acids. The preferred acid esters are sulphuric acid esters of a hydroxyl group-containing polypropylene oxide in the form of their ammonium or alkali metal salts or their salts with tertiary, secondary or primary amines. Suitable polyoxyethylene esters are those prepared by condensing ethylene oxide with lauric, palmitic, stearic, linoleic, ricinoleic and especially oleic acid. Preferred block copolymers are those derived from ethylene- and 1,2-propylene-oxide. Halogenated hydrocarbons may be used as auxiliary blowing agents. Suitable catalysts are tertiary amines and organic compounds of metals particularly those of tin, iron, manganese and lead. Flame retardants such as tris-b -chloroethylphosphate, antimony oxide or tris-2,3-dibromopropyl phosphate may also be incorporated into the reaction mixture.</p> |
