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:
Nov. 12, 1991
Filed:
Jun. 21, 1990
Joachim Meyke, Hanover, DE;
Gerhard Martin, Hanover, DE;
Hermann Berstorff Maschinenbau GmbH, Hanover, DE;
Abstract
A method of extruding a foamed thermoplastic plastics material wherein the thermoplastic plastics material, together with a pore regulating agent, is introduced into an extruder and is fused. Gaseous nitrogen, in an amount of 0.2% to 0.5% by weight, and an incompletely halo-substituted hydrocarbon, in an amount of from 0.5% to 2% by weight, are sequentially injected into the fused mixture. The injected material then enters an extrusion head in which the mixture is maintained at a pressure in excess of 55 bar and the temperature thereof is maintained above a temperature pre-determined in dependence upon the nature of the plastics material. The material foams as it leaves the extrusion head.