PURPOSE: A modified polymethylenepolyphenyl polyisocyanate composition used in the production of low-density rigid urethane foams, prepared by forming carbamate groups by reaction with a lower alcohol.
CONSTITUTION: A modified polyisocyanate is prepared by adding dropwise a lower alcohol of about 1W4C to a polymethylenepolyphenyl polyisocyanate of the formula, wherein n≥1, with agitation in an inert atmosphere to react the components thereby to convert below 10% of the isocyanato groups into carbamate groups. With respect to the conditions for said reaction, for example, in case where a polymethylenepolyphenyl isocyanate containing 30% of isocyanato groups is used, it is preferred to conduct the reaction at about 25W80°C by using below about 2.3% based on the isocyanato groups, of methanol.
IWASAKI MASAO
MURAISHI TERUO
| JP44016673A | ||||
| JP45020700A | ||||
| JPS4745333A | ||||
| JPS5018597A | 1975-02-27 | |||
| JPS50142541A | 1975-11-17 |