| 摘要 |
Flexible cellular polyurethanes are prepared by reacting, in the presence of water as blowing agent and of an organotin catalyst, a polyalkylene ether polyol having an average M.W. 750-400 and OH No.30-100 and a polyisocyanate having an amine equivalent of 90-125 and comprising an undistilled toluene diamine phosgenation product optionally diluted with up to 85% by weight of distilled phosgenation product. From 2 to 5% by weight of the polyol of water may be used and this may be augmented by up to 10% by weight of an organic blowing agent, e.g. methylene chloride or a fluorocarbon. The polyol may be a condensation product of 1,2-propylene oxide and a triol. The polyisocyanate may be the undistilled phosgenation product of a mixture of 2,4- and 2,6-toluene diamine and may be present so as to provide 0.9 to 1.1 isocyanate groups for each OH group of the polyol. The organotin catalyst which may be stannous octoate or dibutyl tin dilaurate may be present at between 1 to 5% by weight of the polyol. The reaction mixture is preferably substantially free from surfactants. |
