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AssigneeBASF SE
InventorsMichael Reichelt, Udo Rotermund, Renate Hempel, Peter Falke, Peter von Malotki, Holger Seifert
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Prepolymers which contain isocyanate groups, have an NCO content of at least 30.0% by weight and can be prepared by reacting an isocyanate mixture consisting predominantly of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates and having a proportion of two-ring isomers of not more than 74% by weight with at least 4-functional polyols or a mixture of polyols having a mean functionality of at least 4, where the polyols or polyol mixtures have a hydroxyl number of from 200 to 1650 mg KOH/g and a number average molecular weight of less than 1100 g/mol. The present invention also provides a process for preparing these prepolymers containing isocyanate groups, provides for their use for producing polyurethanes and provides a process for producing polyurethanes by reacting at least one novel prepolymer containing isocyanate groups, if desired in admixture with further organic and/or modified organic isocyanates (a), with compounds having at least two reactive hydrogen atoms (b) in the presence of, if desired, blowing agents (c), catalysts (d) and, if desired, further auxiliaries and/or additives (e).
A prepolymer containing isocyanate groups, having an NCO content of at least 30.0% by weight comprising a reaction product of an isocyanate mixture of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates and having a proportion of two-ring isomers of from 25% to 70% by weight based on the total weight of said isocyanate mixture and an at least 4-functional polyol or a mixture of polyols having a mean functionality of at least 4, where the polyol or polyol mixture has a hydroxyl number of from 200 to 1,650 mg KOH/g and a number average molecular weight of less than 1100 g/mol.
A process for preparing prepolymers containing isocyanate groups comprising reacting an isocyanate mixture of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates and having a proportion of two-ring isomers of 25% to 70% by weight based on the total weight of said isocyanate mixture with an at least 4-functional polyol or a mixture of polyols having a mean functionality of at least 4, where the polyol or polyol mixture has a hydroxyl number of from 200 to 1650 mg KOH/g and a number average molecular weight of from 136 to 1090 g/mol.
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