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:
Aug. 27, 1991
Filed:
Mar. 13, 1989
Bayer Aktiengesellschaft, Leverkusen, DE;
Abstract
The present invention is directed to a process for the production of polyisocyanate mixtures containing isocyanurate groups and uretdione groups in a molar ratio of about 1:9 to 9:1 by oligomerizing a portion of the isocyanate groups of hexamethylene diisocyanate using trialkyl phosphines and/or peralkylated phosphorus acid triamides as the catalysts which accelerate the dimerization and trimerization of isocyanate groups, terminating the reaction at the desired degree of oligomerization by the addition of a catalyst poison and removing unreacted hexamethylene diisocyanate to a residual content of at most 0.5% by weight, characterized in that, before addition of the catalyst, the hexamethylene diisocyanate starting material is freed from carbon dioxide to a residual content of less than 20 ppm (weight). The present invention is also directed to the polyisocyanates containing uretdione groups and isocyanurate groups obtainable by this process and their use, optionally blocked by blocking agents for isocyanate groups, as the isocyanate component for the production of polyisocyanate polyaddition products.