| 摘要 |
<p>Cellular foams, particularly polyisocyanurate foams, are prepared by reacting together an organic polyisocyanate, a blowing agent, a trimerization catalyst, and a minor amount of a polyol mixture prepared by the transesterification with a glycol of a by-product fraction from the manufacture of dimethyl terephthalate, the major portion of said fraction comprising about 15 to 70 weight percent of dimethyl terephthalate, and about 85 to 30 weight percent of a mixture of monomethyl terephthalate, bi-ring esters and polymeric materials. Laminates of such foams exhibit a high degree of fire resistance, low smoke evolution on combustion, low foam friability and high compressive strength.</p> |
