Method for producing polylaurolactam powder compositions for the coating of metals at high temperatures and their use in the manufacture of pigmented powders by the dry-blend process

US4273919A · kind A · utility

Assignee

• Chemische Werke Huels Aktiengesellschaft · US

Inventors

• Rainer Feldmann · Marl, DE
• Karl Muller
• Karl-Heinz Hornung · Marl, DE

Key dates

• Filing date: Nov 21, 1979
• Grant date: Jun 16, 1981
• Expiry date: Nov 21, 1999

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S524/904
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

A process for preparing coating powders based on polylaurolactam for the vitrification coating process beginning with polylaurolactam granulates obtained by polymerizing laurolactam under internal pressure in the presence of 2 to 10% by wt. of water and 0.3 to 0.7% by wt. of phosphoric acid at temperatures between 265.degree. and 300.degree. C., in the absence of chain stabilizers, and which have a relative viscosity of between 1.50 and 1.80. After precooling to temperatures between -50.degree. and 0.degree. C., the granulates are ground and then graded. Extraction with methanol or ethanol is carried out prior to grinding or grading. Pigments are added to the monomerous laurolactam or to the polylaurolactam in the molten state prior to granulation. The powders are especially well suited to manufacture colored powders by the dry-blend process.