PURPOSE: To prepare the titled polyethylene suitable for use as a high-performance heat insulating material, by stretching a plate-like material formed out of a kneaded mixture of a polyethylene, a solvent, and a void-forming material, followed by removing the solvent.
CONSTITUTION: 100pts.wt. polyethylene (the weight-average-molecular weight of about 104W5×105; the density of at least 0.94g/cm3), about 50W1,000pts.wt. solvent (e.g. a liquid paraffin or tetralin), and about 0.5W10pts.wt. void-forming material (a compound containing an alkyl radical of 6W20C, e.g. a metallic soap or a nonionic surface active agent) are kneaded at a temperature above the melting temperatures of the polyethylene and of the void-forming material, which compound is extruded in the form of plate to be cooled. Then the plate-like material is stretched, using a rolling machine, a stretching machine, etc., at about 60W120°C to a thickness about 0.5W0.025 times its thickness before stretched, and the contained solvent is removed by volatilization, extraction, etc. to produce the microporous polyethylene.
IIDA SHIYOUZOU
SUZUKI KENJI
KAWASE KAORU
