| 摘要 |
NOVEL POLYISOCYANATE BASED UPON 4,4'- AND 2,4'-DIPHENYLMETHANE DIISOCYANATES AND USE THEREOF IN A RIM PROCESS Novel liquid, room temperature polyisocyanate having isocyanate group contents of from 6 to 31% by weight, are prepared by reacting: a) a methylene-bis(phenyl isocyanate) containing 1) from 65 to 90% by weight of the 4,4'-isomer, 2) from 10 to 35% by weigh of the 2,4'-isomer, and 3) no more than 2% by weight of the 2,2'-isomer, with the percents of components a)1), a)2), and a)3) totalling 100%, and b) a mixture of: 1) one or more organic compounds having molecular weights of from 400 to 6000 and containing from 2 to 8 isocyanate reactive groups, and 2) one or more organic diols having molecular weights of from 60 to 200, excluding tripropylene glycol, the weight ratio of component b)1) to b)2) being from 150:1 to 5:1. When used in a RIM process, molded products are obtained which have improved tear strength, improved flexural modulus, improved impact resistance, and improved tensile strength.
|
