US 6,887,539 B2Granted

Polyethylene heat shrinkable tube

AssigneeSumitomo Electric Fine Polymer, Inc.

InventorsKoji Muto, Taro Fujita, Shinya Nishikawa, Hiroshi Hayami

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Abstract

The present invention improves the concentricity after expansion process of a heat shrinkable tube which is required to have a thin wall and hardness, and further aims to obtain elongation of 100% or more in a heat aging test, copperstability test, and heat shock test. The heat shrinkable tube satisfying such aim uses a medium- or high-density polyethylene that has a molecular weight distribution (Mw/Mn) of 30 to 55, an MFR of 0.05 to 0.2, and a specific gravity of 0.94 to 0.96. A medium- or high-density polyethylene obtained by combining an ethylene-vinyl acetate copolymer, ethylene-ethylacrylate copolymer, ethylene-methylacrylate copolymer, and ethylene-ethylmethacrylate copolymer may be used. More preferably, for an antioxidant, phenol-based and sulfur-based antioxidants are used together and zinc oxide is added.

Claims2

Dependent claims

A heat shrinkable tube formed of a polyolefin resin composition, wherein said polyolefin resin composition comprises:

(A) 60% or more of middle to high density polyethylene defined in the following ranges:
(a) molecular weight distribution (Mw/MN) of 30-55, wherein Mw represents weight-average molecular weight and MN represents number-average molecular weight;
(b) melt flow rate (MFR) of 0.05 to 0.2;
and
(c) specific gravity of 0.94 to 0.96;
(B) phenol resin-based antioxidant,
(C) sulfur-based antioxidant, and
(D) zinc oxide,
and, said polyolefin resin composition is formed into a tube, then, cross-linked by irradiation by an electron beam, and the tube is expanded in diameter at temperatures of not lower than softening point, said expanded tube having a concentricity of 25% or less, where the concentricity is equal to (maximum wall thickness−minimum wall thickness)/maximun wall thickness×100.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/196,294Filed 17 Jul 2002
Priority: JP 2001-21638017 Jul 2001
Published: US 2003/0026926 A16 Feb 2003
Granted: 3 May 2005
Term ends: Not estimatedThe source records don’t support an estimate.

Classification12 codes

B29C 61/003
Shaping by liberation of internal stresses; Making preforms having internal stresses; Apparatus therefor: characterised by the choice of material
H01B 3/441
Vinyl resins; acrylic resins: from alkenes
B29C 61/08
Making preforms having internal stresses, e.g. plastic memory: by stretching tubes
B29K 2023/06
Polymers of ethylene: pE, i.e. polyethylene