Method for producing cross-linked polyethylene- based resin expanded beads

Patent metadata

Field	Value
Publication number	US-2016009888-A1
Application number	US-201514791885-A
Country	US
Kind code	A1
Filing date	Jul 6, 2015
Priority date	Jul 9, 2014
Publication date	Jan 14, 2016
Grant date	—

Abstract

A method for producing cross-linked polyethylene resin expanded beads, including dispersing polyethylene resin particles containing a halogen-containing flame retardant in a dispersing medium in an autoclave, impregnating the dispersed resin particles with an organic peroxide and cross-linking the polyethylene resin therewith at a specific temperature range determined by the melting point of the polyethylene resin and by melting point or glass transition temperature of the flame retardant, impregnating the dispersed resin particles with a blowing agent, and then foaming and expanding the resulting cross-linked polyethylene-based resin particles.

First claim

What is claimed is:

1 . A method for producing cross-linked polyethylene-based resin expanded beads, comprising the steps of:
(a) dispersing polyethylene-based resin particles containing a halogen-containing flame retardant in a dispersing medium that is contained in a closed vessel, said polyethylene-based resin having a melting point of TM PE ; (b) impregnating the dispersed polyethylene-based resin particles with an organic peroxide and cross-linking the polyethylene-based resin of the dispersed polyethylene-based resin particles with the organic peroxide at a cross-linking temperature T1 that is not lower than TM PE and is not higher than TM PE plus 80° C.; (c) impregnating the dispersed polyethylene-based resin particles with a blowing agent; and (d) then foaming and expanding the resulting cross-linked polyethylene-based resin particles, which have been impregnated with the blowing agent, wherein the cross-linking temperature T1 satisfies the following relationship:
T 1< T 2+30° C.

where T2 is a melting point or a glass transition temperature of the halogen-containing flame retardant, whichever is the lower.

2 . A method according to claim 1 , wherein the resulting cross-linked polyethylene-based resin particles, which have been impregnated with the blowing agent are released from the closed vessel to an atmosphere having a pressure lower than that in the closed vessel to foam and expand the cross-linked polyethylene-based resin particles.

3 . A method according to claim 1 , wherein T2 is 130 to 350° C.

4 . A method according to claim 1 , wherein the halogen-containing flame retardant is present in the polyethylene-based resin particles in an amount of 3 to 30 parts by weight based on 100 parts by weight of the polyethylene-based resin.

5 . A method according to claim 1 , wherein the halogen-containing flame retardant is selected from the group consisting of brominated epoxy resins, brominated polyphenylene ethers and brominated triazine compounds.

6 . A method according to claim 1 , wherein the halogen-containing flame retardant is a brominated epoxy resin having a weight average molecular weight of 8,000 to 80,000.

7 . A method according to claim 1 , wherein the halogen-containing flame retardant is a brominated polyphenylene ether having a weight average molecular weight of 700 to 3,000.

8 . A method according to claim 1 , wherein the dispersed polyethylene-based resin particles is impregnated with the organic peroxide at a temperature of 60 to 130° C.

9 . A method according to claim 1 , wherein the organic peroxide has a one hour half life temperature of 100 to 150° C.

10 . A method according to claim 1 , wherein the polyethylene-based resin particles contain antimony trioxide in an amount of 1 to 10 parts by weight based on 100 parts by weight of the polyethylene-based resin.

11 . A method according to claim 1 , wherein the cross-linked polyethylene-based resin expanded beads have an apparent density of 15 to 200 g/L.

Assignees

• Jsp Corp

Inventors

• Oikawa Masaharu
• Nohara Tokunobu
• Koshita Nobumasa

Classifications

• C08J9/18 Primary

  by impregnating polymer particles with the blowing agent · CPC title

• C08J2323/06

  Polyethene · CPC title

• C08J9/0023

  containing oxygen · CPC title

• C08J9/0061

  characterized by the use of several polymeric components · CPC title

• C08J9/0028

  containing nitrogen · CPC title