Polyhydroxyalkane/aromatic diamine chain extenders
AssigneeEthyl Corporation
InventorsJ. Kenneth Presswood, James H. Simon, Christopher J. Nalepa
Life of this patent
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Abstract
Blends of 90-99 mol % of a polyhydroxyalkane containing 2-6 carbons and 2-3 hydroxyl groups and 1-10 mol % of an aromatic diamine having a pKb value greater than 11.3 are useful as chain extenders for polyurethanes derived from diphenylmethanediisocyanate (MDI) prepolymers. Their use overcomes the sensitivity to stoichiometry common to MDI prepolymer/polyhydroxyalkane systems and leads to the formation of cast elastomers having better green strength and a shorter demold time. The preferred blends are blends of 1,4-butanediol and di(alkylthio)toluenediamines.
Claims24
A blend of 90-99 mol % of a polyhydroxyalkane containing 2-6 carbons and 2-3 hydroxyl groups and 1-10 mol % of an aromatic diamine having a pKb value greater than 11.3.
A polyurethane prepared by reacting (A) a chain extender comprising 90-99 mol % of a polyhydroxyalkane containing 2-6 carbons and 2-3 hydroxyl groups and 1-10 mol % of an aromatic diamine having a pKb value greater than 11.3 with (B) a diphenylmethanediisocyanate prepolymer.
A process which comprises (A) casting into a mold a reaction mixture of a diphenylmethanediisocyanate prepolymer and a chain extender comprising 90-99 mol % of a polyhydroxyalkane containing 2-6 carbons and 2-3 hydroxyl groups and 1-10 mol % of an aromatic diamine having a pKb value greater than 11.3, (B) curing the reaction mixture in the mold at a temperature of about 90.degree.-110.degree. C. to form a polyurethane, and (C) removing the polyurethane from the mold.
Dependencies are inferred from the claim text.