| 摘要 |
PURPOSE: Provided is a stable liquid polyisocyanate composition with low temperature stability combined with desirable reactivity comparable to liquid MDI/tripropylene glycol adducts and provision of excellent physical properties (combination of hardness, elongation, and tensile strength) in resulting polyurethane elastomers. CONSTITUTION: The polyisocyanate composition characterized by improved freeze stability, and having an NCO group content of from 15 to 30%, having a monomeric diphenylmethane diisocyanate content of less than 90% by weight, comprises (A) an allophanate-modified MDI having an NCO group content of 16 to 32.5% and comprising the reaction product of: (1) diphenylmethane diisocyanate containing from about 0 to about 20% by weight of the 2,4'-isomer, from about 0 to about 2% by weight of the 2,2'-isomer and the balance being the 4,4'-isomer, and (2) an aliphatic alcohol; (B) a low molecular weight branched aliphatic dihydroxy compound; and (C) at least one epoxide functional compound, wherein (C) is present in an amount of from 0.01 to 1% by weight, based on the combined weight of components (A) and (B).
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