Diphenylmethane diisocyanate based polyisocyanates containing allophanate groups and having blocked isocyanate groups

US5705593A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Lutz Schmalstieg · Neunburg vorm Wald, DE
• Josef Pedain · Cologne, DE
• Theodor Engbert · Recklinghausen, DE
• Holger Casselmann · Odenthal, DE
• Frank Kobelka · Leverkusen, DE

Key dates

• Filing date: Sep 10, 1996
• Grant date: Jan 6, 1998
• Expiry date: Sep 10, 2016

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08G18/8093
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

The present invention relates to polyisocyanates prepared from diphenylmethane diisocyanate wherein at least 95% of the isocyanate groups are blocked with diethyl malonate and wherein the polyisocyanates have, based on solids, PA1 A) a content of unblocked and blocked isocyanate groups (calculated as NCO) of 9% to 13%, PA1 B) a content of allophanate groups (calculated as C.sub.2 HN.sub.2 O.sub.3, molecular weight 101) of 3% to 9% and PA1 C) a calculated average functionality of 2.0 to 2.5. The present invention also relates to a process for the production of these polyisocyanates and to their use as crosslinking agents for organic polyhydroxyl compounds in polyurethane stoving lacquers.