| 摘要 |
1,183,224. Polyurethane foams. SOC. QUILLERY. 27 Feb., 1967 [2 March, 1966], No. 9155/67. Headings C3C and C3R. Moulded polyurethane foams having a compact surface and a cellular internal structure and having an overall density between 50 and 500 g/dm.<SP>3</SP> are prepared by mixing a polyisocyanate containing at least two NCO radicals, catalysts, a blowing agent other than water and polyfunctional compounds comprising 5 to 40% on an equivalent basis of the total NCO radicals, of at least one long chain component having an equivalent weight per active hydrogen atom greater than 750 and at least one short chain component having an equivalent weight per active hydrogen atom of less than 200 and being present in an amount corresponding to the remaining 95 to 60% on an equivalent basis of the total NCO radicals, the proportion of water present being less than 25% on an equivalent basis of the total NCO radicals, the ratio of the long chain component to the short chain component being such that the equivalent weight of the moulded polyurethane foam measured per number of groups formed by reaction between the NCO radicals and active hydrogen groups is 200 to 800, the polyisocyanate constituent and/or the polyfunctional compounds carrying benzene rings and being chosen so as to ensure that each part of the polyurethane molecule which has been originated from the polyisocyanate and the short chain component and which is disposed between adjacent portions derived from the long chain component comprises at least six benzene rings, the equivalent weight of the moulded polyurethane foam being between 300 and 800 per benzene ring. Numerous examples are given in which the polyisocyanates are suitably toluene diisocyanates or diphenylmethane diisocyanates, the long chain components are polyethers and the short chain components are diols, diamines or amino-alcohols. |
