Polypropylene resin foamed particles, in-mold foam molded body of polypropylene resin, and method for manufacturing same

Patent metadata

Field	Value
Publication number	US-2018186959-A1
Application number	US-201815910652-A
Country	US
Kind code	A1
Filing date	Mar 2, 2018
Priority date	Oct 15, 2014
Publication date	Jul 5, 2018
Grant date	—

Abstract

A method of producing a polypropylene resin in-mold expanded product, includes: placing polypropylene resin particles obtained from a base material resin having a melting point of 140° C. to 150° C., the base material resin comprising: a polypropylene resin A comprising 3 weight % to 15 weight % of 1-butene and haying a melting point of 130° C. to 140° C.; and a polypropylene resin B having a melting point of 145° C. to 165° C., water, and an inorganic gas foaming agent in a pressure-resistant container, forming a mixture, dispersing the polypropylene resin particles while stirring the mixture, obtaining a dispersion liquid, increasing a temperature and a pressure in the pressure-resistant container, releasing the dispersion liquid from the pressure-resistant container into a region having a pressure lower than the pressure in the pressure-resistant container, producing expanded polypropylene resin particles; and filling a mold with the expanded polypropylene resin particles, and then heating the expanded polypropylene resin particles.

First claim

1 - 18 . (canceled)

19 . A method of producing a polypropylene resin in-mold expanded molded product, comprising:
placing polypropylene resin particles, water, and an inorganic gas foaming agent in a pressure-resistant container, forming a mixture, wherein the polypropylene resin particles is obtained from a base material resin having a melting point of 140° C. to 150° C., the base material resin comprising:
a polypropylene resin A comprising 3 weight % to 15 weight % of 1-butene and having a melting point of 130° C. to 140° C.; and
a polypropylene resin B having a melting point of 145° C. to 165° C.,
dispersing the polypropylene resin particles while stirring the mixture, obtaining a dispersion liquid, increasing a temperature and a pressure in the pressure-resistant container, releasing the dispersion liquid from the pressure-resistant container into a region having a pressure lower than the pressure in the pressure-resistant container, producing expanded polypropylene resin particles each having an average cell diameter of 100 μm to 340 μm; and obtaining the polypropylene resin in-mold expanded molded product by filling a mold with the expanded polypropylene resin particles, and then heating the expanded polypropylene resin particles, wherein the polypropylene resin in-mold expanded molded product has a density and a 50%-strained compressive strength satisfying the following:
[50%-strained compressive strength ( MPa )]≥0.0069×[Molded product density ( g/L )]+0.018.

20 . The method according to claim 19 , wherein the polypropylene resin A comprises 2 weight % to 10 weight % of ethylene.

21 . The method according to claim 19 , wherein the inorganic gas foaming agent contains carbon dioxide.

22 . The method according to claim 19 , further comprising:
melting and kneading the polypropylene resin A and the polypropylene resin B in an extruder and obtaining the polypropylene resin particles.

23 . The method according to claim 19 , further comprising:
obtaining the polypropylene resin A by polymerization using a Ziegler catalyst.

24 . The method according to claim 19 , wherein the expanded polypropylene resin particles are each an expanded composite particle comprising:
an expanded polypropylene resin core layer covered with a polypropylene resin covering layer; the expanded polypropylene resin core layer is obtained from a base material resin comprising the polypropylene resin A and the polypropylene resin B; and the polypropylene resin covering layer comprises the polypropylene resin A.

25 . The method according to claim 19 , wherein the expanded polypropylene resin particles are heated with steam having a pressure of 0.22 MPa (gauge pressure) or less.

Assignees

• Kaneka Corp

Inventors

• Yoshida Toru
• Miura Shintaro

Classifications

• B29K2023/12

  PP, i.e. polypropylene · CPC title

• C08J9/232

  by sintering expandable particles · CPC title

• C08J2201/03

  Extrusion of the foamable blend · CPC title

• C08J2323/14

  Copolymers of propene (C08J2323/16 takes precedence) · CPC title

• C08J9/18 Primary

  by impregnating polymer particles with the blowing agent · CPC title