| 摘要 |
Ternary polyurethane-polyisocyanurate-polyurea foams having, by weight of the reaction product, 10 to 35 percent polyurethane, 30 to 55 percent isocyanurate and 20 to 45 percent polyurea, and having a light-weight density in the range of 0.5 to 0.9 pounds per cubic foot, overcome the normal fragile nature and friability of polyisocyanurate and polyurea components while rendering the polyurethane component essentially fire resistant. The resultant foam has excellent heat insulating properties, is semi-flexible, extremely light in weight, and can be inexpensively produced by existing two-component foam dispensing equipment. The process of producing said ternary foam comprises reacting a mixture of 100 parts by weight of an organic polyisocyanurate with: 15 to 25 parts by weight of a polyether polyol having a hydroxyl number of about 28 to 35 and a molecular weight of not more than 6000; 5 to 25 parts by weight of water; 0 to 25 parts by weight of a blowing agent; 0 to 50 parts by weight of a filler-plasticizer-fire retardant; an effective amount of a low activation catalyst to initiate water-isocyanate reaction to produce polyurea and polyol-isocyanate reaction to produce polyurethane; and an effective amount of high activation catalyst to retard the low activation catalyst during the formation of polyisocyanurate while concurrently enhancing the formation of polyisocyanurate. In another embodiment of the process of the invention, water can be replaced by a disubstituted amine for the production of polyurea and by an inert blowing agent for production of cellular foam.
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