Process for multiple-coat reverse coating using polyurethane solutions

US4675211A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Wilhelm Thoma · Leverkusen, DE
• Josef Pedain · Cologne, DE
• Walter Schroer · Leverkusen, DE

Key dates

• Filing date: Apr 11, 1984
• Grant date: Jun 23, 1987
• Expiry date: Apr 11, 2004

Classification

• Technology area (CPC D): Textiles; Paper
• CPC primary: D06N3/14
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

This invention relates to a process for multiple-coat reverse coating using at least two different polyurethane coating solutions, all the coating solutions containing one and the same polar solvent, preferably substantially anhydrous dimethyl formamide. By choosing PA0 (A) surface-coat polyurethane solutions specially made up using high-melting diol chain-extending agents and by using PA0 (B) highly concentrated adhesive-coat polyurethane solutions containing at least 40% by weight of polyurethane, it is possible to effectively prevent the so-called "frostwork effect" when applying the adhesive coat to the surface coat (A) by the reverse coating process and the troublesome "overlamination" off the web-form textile during its lamination onto the PU-layers formed by reverse coating. In addition, recovery of the solvent from the coating solutions is simplified.