JPS58208327A - Resin composition for molding heat-insulating foam layer - Google Patents

Abstract

PURPOSE:The titled resin composition capable of forming fine and uniform cells even when it is used for forming a thick-walled high-expansion ratio, heat-insulating foam layer, prepared by mixing polyethylene with a blowing agent and a specified rubber-like polymer. CONSTITUTION:Use is made of a rubber-like polymer having compatibility with polyethylene and a Mooney viscosity ML1+4 (100 deg.C) >=15, and selected from the group consisting of ethylene/propylene copolymers, ethylene/vinyl acetate copolymers, etc. Namely, a resin composition for molding heat-insulating foam layers is prepared by mixing polyethylene (preferably, one having a MI <= about 0.5g/10min and a density <= about 0.93) with a blowing agent (e.g., azodicarbonamide, Freon) and about 5-150pts.wt. above rubber-like polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin composition for forming a foamed heat insulating layer that can be foamed finely and uniformly.

Foamed insulation layers made of polyethylene are used as insulation layers, for example, in polyolefin pipes for air conditioning and polyolefin pipes for city gas in cold regions, but the bubbles in the foamed insulation layers are fine and uniformly distributed. However, the conventional foam insulation layer has a large foam blade I! This tendency was particularly strong when the thickness of the foamed insulation layer was 10 mm or more and the degree of foaming was 40 inches or more.By the way, the present inventors have developed a resin composition for a foamed insulation layer made of polyethylene. When a specific material, i.e., a rubbery polymer that is compatible with polyethylene and has a Mooney viscosity ML1+4 (at 100°C) of 15 or more is blended into a product and foamed, a foamed heat insulating layer with the above-mentioned thickness and high degree of foaming is created. The present invention has been completed based on the above findings, and it has been found that very good bubbles can be formed even when using polyethylene [hereinafter also referred to as component (A)], a blowing agent [hereinafter referred to as component (B) ), and (also referred to as component), and (component with component)] are provided by a pickling specialist.

Component (3) used in the present invention is a concept that includes not only homopolymers but also copolymers. Examples of carbonaceous materials include polyethylene homopolymers, copolymers of ethylene mainly composed of methylene, propylene, butene, etc., and copolymers of ethylene and other polymers (e.g., vinyl acetate, acrylic acid, methacrylic acid). Examples include copolymers of The preferred melt index of the prison component is 0.5 g/1'0 min or less, and the preferred density is 0.9:(g/min or less).

As component (B), any blowing agent conventionally used can be used, and specific examples include chemical blowing agents such as azodicarbonamide and physical blowing agents such as Freon.

(The Q component is ethylene-propylene copolymer (EP
M), ethylene-propylene-diene terpolymer (EPDM), ethylene-vinyl acetate copolymer (EV
A), polybutene (PB), salt-accumulated polyethylene (C
To APE 8SB, natural rubber, BR, polyimbutylene,
Butyl rubber, polyurethane, 1. ．． 2 Rubbery polymers such as polybutadiene! Preferred examples include EPMXEPD, EVA, and other polyolefin rubbers, which may be used in combination of 2,000 or more. 5 to 150 folds per 100 parts of the ingredient, preferably 10-100 parts
Department.

The resin composition according to the present invention can be formed into a foamed heat insulating layer by a known method such as extrusion molding. On this occasion,(
4) Ingredients, 03) i portion, and (C) formed carp may each be supplied to an extruder, mixed in the extruder, and molded, or the two or three components may be pre-mixed. There is no need to store it and feed it to the molding machine.

The uninvented resin composition has a wall thickness of 1 when molded.
Even when applied to objects with a diameter of 0 m or more and a foaming degree of 40% or more, remarkable effects can be obtained, so there is a sense in using it for such molded products.

Tip Example 112; Comparative Example 3 2 A resin composition consisting of the composition shown in the table was used to extrude the extrusion product (extruder: I50 blades, L/D = 23, extrusion temperature U: 1
20-150℃, drawer fg, )f: 0.5 m/9
r-), outer diameter 60mφ, wall thickness h? A foamed LFR thermal layer was formed on a polyethylene vibe, and the outer covering of the heat insulation layer and the cross section of the foam heat insulation layer were observed. The observation results were also written on the clothes.

(Margin below)

Claims (2)

[Claims] (1) Compatible with polyethylene, a blowing agent, and polyethylene, and has a Mooney viscosity of ML1 and (100°C) of 1
A resin composition for molding a foamed heat insulating layer, which is formed by blending 5 or more rubbery polymers. (2) The foam insulation layer has a wall thickness of 10W or more and a foaming degree of 40
% or more, the resin composition for forming a foamed heat insulating layer according to claim @(1).