| 摘要 |
Polyurethane foam is prepared by reacting an isocyanate-modified polyether polyol or a polyester polyol, the polyol having a hydroxyl number of 25 to 27, with a dimethylbenzene w,w1-diisocyanate in the presence of a blowing agent, a stannoxane of the formula <FORM:1124459/C3/1> where the X's are halogen, OH, C1 to C4 alkoxy, formyloxy, alkylcarbonyloxy having not more than 17 carbon atoms, NCO or NCS and R is C1 to C4 alkyl, and a monoaminoalcohol having up to 4 carbon atoms. The isocyanate-modified polyether polyol may be prepared by reacting excess polyol with a diisocyanate which may also be a dimethylbenzene diisocyanate and this may also take place in the presence of an octaalkyl-stannoxane of the above formula. The polyethers are the usual adducts of alkylene oxides with polyhydric alcohol or amines. The polyesters are also conventional and include the reaction products of lactones with poly-functional initiators. Specified aminoalcohols are 2-aminoethanol, 2-aminopropan-1-ol, 1-aminopropan-2-ol, 2-aminobutan-1-ol, 1-aminopropan-3-ol and 3-aminobutan-1-ol. The blowing agent may be water or water-yielding compounds, halogenated hydrocarbons and nitrogen-yielding compounds, e.g. azo compounds. Tertiary amines as additional catalysts as well as foam stabilizers and other additives may be added. |
