Abstract: This invention relates to a process for the reduction of color of polymethylene poly(phenylisocyanates). This process comprises mixing a polymethylene poly(phenylisocyanate) with an epoxide having an epoxide equivalent weight of about 44 to about 700, and heating this mixture to a temperature of from about 35 to about 150.degree. C. for at least about 15 minutes, with stirring. Suitable epoxides include epoxidized fatty acid monoglycerides, epoxidized fatty acid diglycerides, epoxidized fatty acid triglycerides, epoxidized dimer fatty acids and epoxidized trimer fatty acids.

Abstract: The present invention relates to an improved process for the production of light colored polymethylene polyphenyl polyisocyanates. This process comprises adding a compound that contains an epoxide group to the process at any point prior to quench cooling the formed polyisocyanates.

Abstract: NCO-terminated prepolymers are made by reacting a polymeric diphenylmethane diisocyanate (PMDI) and a polyol having a functionality of from about 1.8 to about 4.0 and a molecular weight of from about 400 to about 2,000. The PMDI and polyol are reacted in amounts such that the equivalent ratio of isocyanate groups to hydroxyl groups is from about 15:1 to about 160:1. These prepolymers are useful in the production of polyurethane foams, particularly laminated foams.

Abstract: A process for the production of polymethylene polyphenyl polyisocyanates is disclosed. The process comprises phosgenating the corresponding polyamines in solution in an inert organic solvent, removing excess phosgene, and stripping the solvent, the improvement wherein at least 0.00015 percent by weight of hydrazine or hydrazine derivative per 100 percent by weight of polyamine are added to the polyamines at any time prior to the stripping step.

Abstract: Disclosed herein is an improved process for preparing a polyamine mixture derived by reacting aniline with formaldehyde in the presence of an acid catalyst the improvement comprising mildly reducing the polyamine mixture by a process step comprising catalytically or chemically hydrogenating the polyamine mixture in the presence of a metal catalyst.

Abstract: The present invention encompasses an improved process for preparing polymethylene polyphenyl polyisocyanate comprising reacting phosgene with polymethylene polyphenyl polyamine, the improvement wherein the polymethylene polyphenyl polyamine is acidified prior to phosgenation.

Abstract: The present invention encompasses an improved process for preparing polymethylene polyphenyl polyisocyanate comprising reacting phosgene with polymethylene polyphenyl polyamine, the improvement wherein the polymethylene polyphenyl polyamine is acidified prior to phosgenation.

Abstract: The present invention is directed to a process for the production of polymethylene polyphenyl polyisocyanates by phosgenating the corresponding polyamines in solution in an inert organic solvent, removing excess phosgene, and stripping the solvent. The improvement resides in adding at least 0.02 parts by weight of reducing agent per 150 parts by weight of polyamine to the polyamines at any time prior to the stripping step.

Abstract: The present invention is directed to a liquid, storage-stable isocyanate prepolymer having an isocyanate group content of from 10 to 30% by weight, prepared by reacting:i) a polyamine containing at least two aromatically bound primary amino groups prepared by hydrolyzing an isocyanate compound having an isocyanate group content of from 0.5 to 40% by weight, withii) an isocyanate mixture comprisinga) from 50 to 100% by weight of diphenylmethane diisocyanates of which from 3 to 50% by weight consist of the 2,2'- and 2,4'-isomers, andb) the balance being polyphenylpolymethylene polyisocyanates, with the proviso that if said mixture comprises from 95 to 100% by weight of diphenylmethane diisocyanate, at least 15% by weight of said diisocyanate consisting of the 2,2'- and 2,4'-isomers.