| 摘要 |
<p>Disclosed is an improved process for the production of organic polyisocyanate based molded polymers prepared from at least one organic polyisocyanate and at least one polyol in the presence of an internal release agent wherein the improvement comprises employing as said agent a polysiloxane having at least one unit of the formula <IMAGE> wherein R is selected from the group consisting of lower-alkyl and aryl, R1 is a divalent hydrocarbon radical, and R2 is selected from the group consisting of lower-alkoxy, aryloxy, particular hydroxyalkyleneoxy, alkoxyalkyleneoxy, amino, and hydroxyalkylamino radicals. The molding process can be repeated in many cycles before the molds require cleaning or treatment with release agent. The ease and rapidity with which the present process can be carried out makes it particularly suited to RIM production methods.</p> |
