Process for coating substrates with polyurethane ureas

US4894428A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Wilhelm Thoma · Leverkusen, DE
• Josef Pedain · Cologne, DE
• Waldemar Kling · Kandern, DE

Key dates

• Filing date: Jan 3, 1989
• Grant date: Jan 16, 1990
• Expiry date: Jan 3, 2009

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T442/2566
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

The present invention is directed to a process for coating substrates with polyurethane ureas which is characterized in that a substrate is coated with a product, which has been obtained by the reation of (A) a prepolymer based on an aromatic polyisocyanate containing on average two ketoxime-blocked NCO groups and having an average molecular weight of about 500 to 15,000 with (B) a chain-extending agent corresponding to the formula EQU H.sub.2 N--R'--NH.sub.2 in which R' is an aliphatic or cycloaliphatic radical, in the presence of solvents at temperatures above 50.degree. C. and at an equivalent ratio of blocked NCO groups to NH.sub.2 groups of 1.43 to 1.02, wherein after about 40 to 90% of the available amino groups have reacted, the reaction is completed with crosslinking at temperatures above 120.degree. C. The present invention is also directed to the coated substrates produced by this process.