초록 ▼

The present invention relates to polyisocyanate mixtures which are reaction products of 4,4′-diphenylmethane diisocyanate as the isocyanate component, are liquid at greater than 5°C. and have an NCO content of 14.5 to 24% by weight and an allophanate group content (calculated as C2HN2O3, molecular w

The present invention relates to polyisocyanate mixtures which are reaction products of 4,4′-diphenylmethane diisocyanate as the isocyanate component, are liquid at greater than 5°C. and have an NCO content of 14.5 to 24% by weight and an allophanate group content (calculated as C2HN2O3, molecular weight =101) of 7.7 to 14.5% by weight; a process for the production of these polyisocyanate mixtures by reacting 4,4′-diphenylmethane diisocyanate as the exclusive isocyanate component with one or more monohydric alcohols having 4 to 16 carbon atoms at an NCO/OH equivalent ratio of 5:1 to 8.5:1 and at a temperature of up to 160°C. to form urethane groups and during or subsequent to urethane formation, converting the urethane groups to allophanate groups in the presence of a catalyst which promotes allophanate formation; and the use of these polyisocyanate mixtures as the polyisocyanate component in two-component polyurethane coating compositions.

대표청구항 ▼

A polyisocyanate mixture which is a reaction product of 4,4′-diphenylmethane diisocyanate, is a liquid a 5°C. and above and has A) an NCO content of 14.5 to 24% by weight and B) an allophanate group content (calculated as C2HN2O3 molecular weight=101) of 7.7 to 14.5 % by weight and C) said reaction

A polyisocyanate mixture which is a reaction product of 4,4′-diphenylmethane diisocyanate, is a liquid a 5°C. and above and has A) an NCO content of 14.5 to 24% by weight and B) an allophanate group content (calculated as C2HN2O3 molecular weight=101) of 7.7 to 14.5 % by weight and C) said reaction product is prepared by reacting a) 4,4′-diphenylmethane diisocyanate with b) one or more monohydric alcohols having 4 to 16 carbon atoms per molecule, at an NCO/OH equivalent ratio of 5:1 to 8.5:1 to form urethane groups and subsequently allophanate groups.