The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 27, 1976
Filed:
Nov. 18, 1974
Edward Thomas Marquis, Austin, TX (US);
Jefferson Chemical Company, Inc., Houston, TX (US);
Abstract
An improved process for the preparation of methylene-bridged polyphenylpolyamine mixtures having increased 4,4'-isomer content in the diaminodiphenylmethane portion by the catalyzed condensation reaction of aniline and formaldehyde is disclosed. Aniline and formaldehyde are mixed and reacted at an elevated temperature in the presence of up to about 3 weight percent of a co-catalyst system comprising about 0.1 to less than about 3.0 weight percent silica-alumina catalyst and from about 0.1 to less than about 3.0 weight percent oxalic acid, basis weight of aniline present. The novel process provides a resulting reaction product that can be easily filtered to remove the solid silica-alumina catalyst therefrom and a reaction product mixture of methylene-bridged polyphenylpolyamine mixtures having an increased 4,4'-isomer content in the diaminodiphenylmethane portion than heretofore obtained utilizing silica-alumina catalysts alone. Methylene-bridged polyphenylpolyamines are useful as epoxy curing agents, urethane cross linkers, as precursors for the preparation of corresponding methylene-bridged polyphenylpolyisocyanates, and the like.