| 摘要 |
<p>1,263,937. Coated products. GLANZSTOFF A.G. 10 July, 1969 [13 July, 1968], No. 34862/69. Heading B2E. Also in [Division C3] Substrates may be coated with polyurethanes prepared by (a) reaction of a polymeric diol of M.W. 700 to 5000 with a diisocyanate having at least one aromatic radical to form a preadduct having terminal isocyanate groups, (b) reaction of the pre-adduct with a mixture of chain extenders, comprising a total of 0.15 to 0.85 mols of one or more compounds selected from diamines, hydrazine and hydrazine derivatives per mol of the pre-adduct and an aliphatic ammo hydroxy compound, the total number of mols of the chain extenders being less than the number of mols of the pre-adduct, (c) addition to the products so obtained, of diphenylmethane -4,4'-diisocyanate and from 0.75 to 0.95 times the molar quantity of this diisocyanate of one or more aliphatic or araliphatic diols, having a M.W. of less than 700 and (d) stopping the reaction by the addition of a monohydric alcohol. The preadduct is usually prepared in the absence of a solvent but in the remaining stages of the process a solvent, e.g. dimethylformamide, dimethylsulphoxide and dimethylacetamide usually is employed. In a typical Example polyethylene adiphate is reacted with diphenylmethane-4,4'-diisocvanate to form a preadduct which is dissolved in dimethylformamide (DMF), reacted with a solution of diethanolamine and ethylene diamine in DMF to form a product to which is added a solution of diphenylmethane-4,4'-diisocyanate in DMF followed by a solution of 1,4-butane diol in DMF. The reaction is terminated with a solution of ethanol in DMF. This polyurethane may be applied to an impregnated web to form an artificial leather.'</p> |
