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. 22, 2003
Filed:
Sep. 25, 1998
Kenji Mogami, Settsu, JP;
Tsuyoshi Mihayashi, Akashi, JP;
Kyoichi Nakamura, Takasago, JP;
Naruhiko Akamatsu, Hyogo, JP;
Kaneka Corporation, Osaka, JP;
Abstract
A water-containing polyolefin resin composition containing a polyolefin resin and a hydrophilic polymer and having a water content of 1 to 50% by weight which is suitable for use in preparation of polyolefin resin pre-expanded particles, and pre-expanded particles of a polyolefin resin prepared by pre-expanding the water-containing polyolefin resin composition the particles having a an apparent expansion ratio of 5 to 60, a closed cell ratio of 80 to 100% and an average cell diameter of 50 to 500 &mgr;m. The pre-expanded particles can be prepared without using a volatile blowing agent by dispersing resin particles made of a polyolefin resin composition containing a polyolefin resin and a hydrophilic polymer into an aqueous dispersion medium in a closed vessel to form a dispersion, heating to a temperature not lower than the softening point of the polyolefin resin to produce water-containing resin particles having a water content of 1 to 50% by weight, and releasing the aqueous dispersion from the closed vessel into a lower pressure than the inner pressure of the closed vessel, thereby expanding the water-containing resin particles. When the releasing of the dispersion from the vessel is conducted after raising the inner pressure to 25 to 75 kg/cm G by introducing nitrogen gas, air or an inorganic gas including them as a main component into the vessel, pre-expanded particles providing foams having good physical properties and a high expansion ratio are obtained.