Dispersant for carbon black-filled foam

Claim 1

A process for producing a closed cell, rigid, isocyanate-based polymer foam which comprises (a) providing in an isocyanate-based polymer foam-forming composition a dispersion of carbon black, the carbon black being present in an amount of at least about 2 percent by weight, based on the weight of the polymer in the foam, an end-capped polyoxyalkylene compound which is nonreactive with isocyanate groups being incorporated in the foam-forming composition, and (b) thereafter foaming and curing the resultant filled foam-forming composition, wherein the polyoxyalkylene compound is present in an amount sufficient to help bring about a uniform dispersion of the carbon black throughout the foam so that there is present in the cell walls of the foam an amount of predominantly non-agglomerated carbon black which reduces the aged k-factor of the foam to below the aged k-factor of the corresponding unfilled foam having the same density and prepared from the same foam-forming composition as the filled foam except that the carbon black is omitted and the amount of foaming agent is adjusted to equalize the densities of the filled and unfilled foams.