Patent ID: 6162380
Filing Date: 2000-12-19
Classification: B29C,B29K

Abstract:
A method of making a hollow foamed plastic body from polyethylene in an extrusion blow-molding process, said method comprising the steps of:a) providing a blowing-agent master batch that disintegrates endothermically and provides a nucleation effect during the blow-molding process, said blowing-agent master batch having an average grain size of about 1 mm;b) making a mixture comprising a polyethylene granulate and a portion of the blowing-agent master batch, said polyethylene granulate comprising high density polyethylene;c) extruding the mixture formed in step b) with a single-screw extruder to form a pre-molded tube blank; andd) blow molding the pre-formed tube blank at a blow-molding pressure of between 0.5 and 2.0 bar with a blow-molding tool having at least one portion of a tool surface at a tool surface temperature of at least 35.degree. C. to form the hollow foamed plastic body.