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.

Abstract: A foamed-polyolefin-insulated wire having a conductor diameter of 0.4 mm or less and an insulation thickness of 0.8 mm or less and satisfying, an equivalent dielectric constant less than 1.6, the fluctuation limits of the equivalent dielectric constant less than or equal to ±0.1, and conductor stripping force greater than or equal to 100 g/50 mm. Polyolefin including 10 weight % or more of an ionomer is used. Polyolefin having a swelling ratio of 55 % or more is extruded over the conductor to form a foamed insulation layer with a foaming degree of 50 % or more using a chemical foaming agent and/or an inert gas. The wire is suitable for high-speed data transmission.

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, copper stability 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.