Preparation of Integral-Skin Flexible Foams

Preparation of Integral-Skin Flexible Foams. The major polyisocyanates for use in making integral-skin flexible urethane foams are liquid MDl and TDl prepolymers. In order to make light-stable integral-skin foams, aliphatic diisocyanates, e.g., HDl (hexamethylene diisocyanate) and IPDl (isophorone diisocyanate) in modified forms are used. 

Polyols used for the above foams include polyether polyols having a molecular weight of 2,000 to 8,000 and a functionality of two or three. Primary hydroxyl-terminated polyether polyols are preferably used. Chain extenders or crosslinkers are also used with the polyether polyols for the purpose of forming hard segments in the resulting elastomer foams. 

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