Melt coating composition and coating process

US4096291A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Willi Dunwald · Leverkusen, DE
• Jurgen Lewalter · Odenthal, DE
• Wilfried Zecher · Leverkusen, DE
• Wolf-Dieter Last

Key dates

• Filing date: Jan 28, 1975
• Grant date: Jun 20, 1978
• Expiry date: Jan 28, 1995

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/12
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

A process for the low solvent or solvent free coating of heat resistant substrates by using a coating substance which has a melting point or range below about 200.degree. C and which is heat crosslinkable. The substrate is coated at temperatures between about 20.degree. and 250.degree. C and the coating is subsequently heated to more elevated temperatures to effect crosslinking. The coating substance contains active hydrogen, preferably hydroxyl bearing compounds and blocked polyisocyanates which become reactive when the coating substance is heated to effect cross-linking. In a preferred embodiment, the blocked polyisocyanates consist of at least 40 equivalent percent alkanol or cycloalkanol blocked polyisocyanates. Also a coating substance containing at least 50 wt.% of a combination of active hydrogen, preferably hydroxyl bearing compounds and blocked isocyanates. The combination has a melting point of less than 200.degree. C and a blocked isocyanate group to active hydrogen ratio of about 1:2 to 1:9. At least 40 equivalent percent of the blocked polyisocyanates are alkanol or cycloalkanol blocked and the remainder are blocked such that they are reactive at temperatures at least …