Method for manufacturing foamed polypropylene-resin particles

Patent metadata

Field	Value
Publication number	US-2016009887-A1
Application number	US-201414773204-A
Country	US
Kind code	A1
Filing date	Mar 7, 2014
Priority date	Mar 8, 2013
Publication date	Jan 14, 2016
Grant date	—

Abstract

Foamed polypropylene-resin particles are obtained by dispersing polypropylene-resin particles containing polyethylene glycol and/or glycerin together with an aqueous dispersion medium in a pressure-resistant container; introducing carbon dioxide gas as a foaming agent into the pressure-resistant container; impregnating the polypropylene-resin particles with the foaming agent under a heating and pressure condition; and then discharging the polypropylene-resin particles into an area having a lower pressure than an internal pressure of the pressure-resistant container and having an atmosphere temperature of higher than 80° C. and not higher than 110° C. The foamed polypropylene-resin particles can yield an in-mold foam molded body at a low heated water vapor pressure for molding, do not lose moldability at a high heated water vapor pressure for molding, have a wide heated water vapor range for molding, exhibit good moldability even when a mold with a complicated shape, a large mold, or a similar mold is used.

First claim

1 . A method for manufacturing foamed polypropylene-resin particles by a single foaming process, the foamed polypropylene-resin particles having a heat deformation ratio of −2% or more and +2% or less, the heat deformation ratio being a ratio of change in apparent bulk density before and after heating at a temperature 15° C. lower than a melting point of a polypropylene resin as a substrate resin, the foamed polypropylene-resin particles having an expansion ratio of 15 or more and 45 or less, the method comprising:
dispersing polypropylene-resin particles containing polyethylene glycol and/or glycerin together with an aqueous dispersion medium in a pressure-resistant container;
introducing carbon dioxide gas as a foaming agent into the pressure-resistant container;
impregnating the polypropylene-resin particles with the foaming agent under a heating and pressure condition; and then
discharging the polypropylene-resin particles into an area having a lower pressure than an internal pressure of the pressure-resistant container and having an atmosphere temperature of higher than 80° C. and not higher than 110° C., thereby foaming the polypropylene-resin particles.

2 . The method for manufacturing foamed polypropylene-resin particles according to claim 1 , wherein the foamed polypropylene-resin particles have an expansion ratio of 18 or more and 25 or less.

3 . The method for manufacturing foamed polypropylene-resin particles according to claim 1 , wherein the polypropylene resin is a polypropylene random copolymer containing 1-butene and/or ethylene as a comonomer.

4 . The method for manufacturing foamed polypropylene-resin particles according to claim 3 , wherein the polypropylene random copolymer has a melting point of 125° C. or higher and 155° C. or lower.

5 . The method for manufacturing foamed polypropylene-resin particles according to claim 1 , wherein the polyethylene glycol and/or glycerin is contained in an amount of 0.01% by weight or more and 2% by weight or less in 100% by weight of the polypropylene-resin particles.

6 . The method for manufacturing foamed polypropylene-resin particles according to claim 1 , wherein the polypropylene resin contains an inorganic nucleating agent.

7 . The method for manufacturing foamed polypropylene-resin particles according to claim 1 , wherein the foaming agent is used in an amount of 3 parts by weight or more and 60 parts by weight or less relative to 100 parts by weight of the polypropylene-resin particles.

8 . One-step foamed polypropylene-resin particles manufactured by the method according to claim 1 .

9 . An in-mold foam molded body produced by in-mold foam molding of the one-step foamed polypropylene-resin particles according to claim 8 .

Assignees

• Kaneka Corp

Inventors

• Fukuzawa Jun

Classifications

• C08J2201/032

  Impregnation of a formed object with a gas · CPC title

• C08J2203/06

  CO2, N2 or noble gases · CPC title

• C08J9/122

  Hydrogen, oxygen, CO2, nitrogen or noble gases · CPC title

• C08J9/228

  Forming foamed products · CPC title

• C08J2323/14

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