Method for producing multi-layer polyethylene resin foam sheet

Patent metadata

Field	Value
Publication number	US-9592642-B2
Application number	US-201313974738-A
Country	US
Kind code	B2
Filing date	Aug 23, 2013
Priority date	Sep 13, 2012
Publication date	Mar 14, 2017
Grant date	Mar 14, 2017

Abstract

A method for producing a multi-layer foam sheet having a foam layer and a resin layer laminated on at least one side of the foam layer, includes coextruding a foamable molten resin composition which contains a low density polyethylene and a physical blowing agent and a molten resin composition which contains 80 to 20% by weight of a specific ethylene-propylene random copolymer and 20 to 80% by weight of a specific polyethylene resin so that the foamable molten resin composition forms the foam layer and the molten resin composition forms the resin layer.

First claim

What is claimed is:

1. A method for producing a multi-layer polyethylene resin foam sheet having a polyethylene resin foam layer and a polyolefin resin layer laminated on at least one side of the polyethylene resin foam layer, comprising the steps of:
providing a foamable molten polyethylene resin composition comprising a polyethylene resin (A) comprising a low density polyethylene, and a physical blowing agent;
providing a molten polyolefin resin composition comprising:
20 to 80% by weight of an ethylene-propylene random copolymer obtained using a metallocene polymerization catalyst and having a melting point of 135° C. or lower, and
20 to 80% by weight of a polyethylene resin (B) selected from the group consisting of low density polyethylene, linear low density polyethylene, high density polyethylene and mixtures thereof, wherein
a sum of the ethylene-propylene random copolymer and the polyethylene resin (B) is 100% by weight, and
a ratio η PP /η PEB of a melt viscosity η PP of the ethylene-propylene random copolymer at 190° C. and a shear rate of 100 sec −1 to a melt viscosity η PEB of the polyethylene resin (B) at 190° C. and at a shear rate of 100 sec −1 is not lower than 0.4 and not higher than 1.5;
a bonding strength between a polyethylene resin foam layer and a polyolefin resin layer of the multi-layer foam sheet is 4 N/cm or more; and
the bonding strength is measured by 180 peel test as referenced in HS K6854-2(1999); and

coextruding the foamable molten polyethylene resin composition and the molten polyolefin resin composition to form the multi-layer polyethylene resin foam sheet,
wherein the foamable molten polyethylene resin composition forms the polyethylene resin foam layer and the molten polyolefin resin composition forms the polyolefin resin layer.

2. The method according to claim 1 , wherein the molten polyolefin resin composition has a melt viscosity η PO of not lower than 500 Pa·s and not higher than 1,500 Pa·s at a temperature of 190° C. and a shear rate of 100 sec −1 .

3. The method according to claim 1 , wherein the polyethylene resin (B) is a linear low density polyethylene obtained using a metallocene polymerization catalyst.

4. The method according to claim 1 , wherein the polyethylene resin foam layer has an apparent density of not lower than 90 kg/m 3 and not higher than 600 kg/m 3 and a closed cell content of not lower than 70%.

Assignees

• Jsp Corp

Inventors

• Morita Kazuhiko
• Kakuta Hirotoshi
• Taniguchi Ryuichi

Classifications

• B29L2009/00

  Layered products · CPC title

• B29C44/24 Primary

  Making multilayered articles · CPC title

• C08L23/142

  at least partially crystalline copolymers of propene with other olefins · CPC title

• B32B27/08

  of synthetic resin · CPC title

• B32B27/065

  of foam · CPC title