The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 25, 1980
Filed:
Jul. 13, 1978
Rainer Feldmann, Marl, DE;
Hans-Joachim Panoch, Haltern, DE;
Heinz Scholten, Haltern, DE;
Roland Feinauer, Marl, DE;
Chemische Werke Huls AG, Marl, DE;
Abstract
Polylaurolactam powder coating compositions for the coating of metals at high temperatures are obtained by grinding low molecular weight and brittle polylaurolactam with subsequent condensation by heating of the powder to temperatures of below its melting point. A. For the production of pigment free polylaurolactam powders, the low molecular weight granules are ground at temperatures of between 0.degree. and 45.degree. C. which have a relative viscosity of between 1.25 and 1.45 (measured in a 0.5 percent mecresol solution at 25.degree. C.) and have been produced by the polymerization of laurolactam in the presence of 2-10 percent by weight of water, 0.3-0.7 percent by weight of phosphoric acid at temperatures of between 265.degree. and 300.degree. C. in the absence of chain stabilizers under internal pressure, with subsequent granulating, and extraction between 25.degree. and 70.degree. C. with methanol or ethanol. The subsequent condensation is conducted at temperatures of between 140.degree. C. and below the melting point of the polyamide to relative viscosity value of between 1.55 and 1.65; and finally the powders obtained are brought to a particle size distribution of between greater than 60 and less than 350 microns. B. For the production of pigmented polylaurolactam powders, the low molecular weight granules are treated at temperatures of between 110.degree. and 140.degree. C. and pressures of between 5 and 8 bars with the addition of pigments in primary aliphatic alcohols having 1-3 carbon atoms, cyclohexanol, or ethylbutanol, these granules having a relative viscosity of between 1.25 and 1.65 and likewise having been obtained by the polymerization of laurolactam in the presence of 2-10 percent by weight of water, 0.3-0.7 percent by weight of phosphoric acid at temperatures of between 265.degree. and 300.degree. C. in the absence of chain stabilizers under internal pressure, with subsequent granulating, and extraction between 25.degree. and 70.degree. C. with methanol or ethanol. The powders are obtained with gradual cooling to room temperature with a minimum of mechanical motion and these powders are dried, optionally screened and, if necessary, the thus-extracted granules or the dried powders are brought to relative viscosity value of between 1.55 and 1.65 by subsequent condensation at temperatures of between 140.degree. C. and below the melting point of the polyamide.