Expanded particles of polyolefin resin and process for producing same
AssigneeKanegafuchi Kagaku Kogyo Kabushiki Kaisha
InventorsKenichi Senda, Masao Ando, Kyoichi Nakamura, Kiyoshi Mori, Tatehiko Nishida
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Abstract
The mixture of water and the polyolefin resin particles impregnated with a volatile blowing agent are released from the interior of the pressure-resistant container under a constant temperature and constant pressure preferably keeping the partial pressure of the blowing agent constant, through at least one orifice having an area of 0.07 to 300 mm.sup.2, into a low-pressure zone. This invention gives various advantages when applied to the practical process resulting in expanded particles with superior properties which are free of blocking and remarkably uniform in the degree of expansion, and are useful for molding.
Claims7
A process for producing expanded particles of a polyolefin resin characterized by dispersing polyolefin resin particles 0.25 to 10 mm in particle size and a volatile blowing agent in water in the presence of a dispersant within a pressure-resistant container, heating the mixture at a temperature within the range of from the melting point of crystals of the resin minus 25.degree. C. to the melting point plus 10.degree. C. to impregnate the resin particles with the blowing agent, and releasing the mixture of the particles and water into a low-pressure zone through at least one orifice having an area of 0.07 to 300 mm.sup.2 while maintaining the interior of the container at a constant temperature and constant pressure.
Dependencies are inferred from the claim text.