Uniroyal Chemical Company, Inc.

Ajaib Singh

Ronald Owen Rosenberg

Brian Scott Lombardo

Christopher James Maupin

Ronald Walter Fuest

Robert John Quint

Polyurethane prepolymers are disclosed prepared with mononuclear aromatic diisocyanate such as toluene diisocyanate and an aliphatic diisocyanate such as H12MDI. These prepolymers can be cured with 4,4'-methylene-bis-(3-chloro-2,6-diethylaniline) to form a cured urethane elastomer with reduced propensity to crack during the curing process, extended pour life (a slower rate of viscosity buildup after curative and prepolymer are mixed), low hysteresis, and a low level of free toluene diisocyanates and/or other toxic or volatile substances to increase worker safety during processing. It has also been found that prepolymers made from toluene diisocyanate and cured with a blend of two aromatic diamine curatives yields urethane elastomers with the same reduced propensity to crack during the curing process.

Polyurethanes cured with

A process for reducing the amount of residual organic diisocyanate monomer in a polyurethane prepolymer reaction product mixture which comprises distilling the polyurethane prepolymer reaction product mixture in the presence of a combination of at least one inert first solvent with a boiling point below the boiling point of the residual organic diisocyanate monomer and at least one inert second solvent with a boiling point above the boiling point of the residual organic diisocyanate monomer, at a temperature which exceeds the vaporization temperature of the residual organic diisocyanate monomer and which is below the decomposition temperature of the polyurethane prepolymer.

Removal of unreacted diisocyanate monomer from polyurethane prepolymers

A low-free toluene diisocyanate prepolymer is formed by reaction of a blend of the dimer of 2,4-toluene diisocyanate and an organic diisocyanate, preferably isomers of toluene diisocyanate, with high molecular weight polyols and optional low molecular weight polyols. The prepolymer can be further reacted with conventional organic diamines or organic polyol curatives to form elastomeric polyurethane/ureas or polyurethanes.

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Huntington, CT, United States of America

Ajaib Singh