| 摘要 |
1283467 Polyurethanes MARATHON OIL CO 20 May 1970 [4 June 1969] 24460/70 Headings C3C and C3R [Also in Division C2] Polyurethanes and polyureas having improved flame-resistant properties are obtained from polyisocyanates containing both isocyanate and isocyanurate groups attached to polyvalent organic radicals through methylene or substituted methylene groups and in which (a) from 0À1 to 75 mole per cent of the total nitrogen content is in the form of isocyanurate rings, (b) 5 to 50 wt. per cent of the polyisocyanate is chlorine, bromine or iodine, at least part of which is present as a haloalkyl group, and (c) the polyisocyanate contains at least 0À5 milliequivalents of isocyanate groups per gram, this product being obtained by reaction of an organic compound containing at least two chloroalkyl groups with an alkali or alkaline earth metal bromide or iodide and an alkali or alkaline earth metal cyanate in the presence of an aprotic dipolar solvent. In an example, the isocyanate obtained by reaction of tris-chloromethyl toluene, sodium cyanate and sodium bromide is formed into a prepolymer by addition of the propylene oxide-trimethylol propane based trio@ Pluracol (Registered Trade Mark), and this is formed into a rigid foam by reaction of a component comprising the prepolymer and a silicone with a component comprising trichlorofluoromethane and the polyol Quadrol (Registered Trade Mark).
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