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:
Jul. 23, 1991
Filed:
Nov. 30, 1989
Edward F Kiczek, Long Valley, NJ (US);
Augustine I Dalton, Jr, Trexlertown, PA (US);
Air Products and Chemicals, Inc., Allentown, PA (US);
Abstract
A process for producing microcellular foamed articles wherein a low pressure compressible, inert gas such as nitrogen is used as a foaming agent. The process comprises introducing a thermoplastic material into an inlet of an extruder having a length to diameter ratio of at least 30:1, said extruder comprising a screw having at least one stage; heating the thermoplastic material in a melt zone to a temperature sufficient to melt or soften the thermoplastic material to form a melted thermoplastic material; injecting an insoluble compressible, inert gas into the melted thermoplastic material at a position approximately 1 to 2 screw diameters downstream of the melt zone; mixing the molten thermoplastic material and the inert, compressible gas to form a homogeneous dispersion of insoluble bubbles within the material; reducing the pressure of the molten thermoplastic material causing the homogeneously dispersed bubbles to expand within the melted thermoplastic material to form a foamed article and cooling the foamed article to a temperature below the melting or softening point of the foamed article.