FOAM INSULATED ELECTRIC WIRE

摘要

PURPOSE:To make the rate of foaming approx. 80% and make bubbles fine and uniform by using a polyolefin resin having a swelling ratio of 60% or more and a melt tension of 6.0g or more as a foam insulating layer. CONSTITUTION:A mixture of a high density polyethylene resin and low density polyethylene resin is adjusted so as to have a swelling ratio of 60% or more and a melt tension of 6.0g or more. Thereto an inorganic talc as inorganic nucleus agent and an azodicarboxylic acid amide as organic nucleus agent are added in certain specified contents, and an insulative resin is prepared using a two-axis mixing/kneading machine. The insulative resin is extruded by an extruder onto a conductor of 2.1mm in diameter and allowed to foam using nitrogen gas, and thereby a foaming insulated electric wire having a specified outside diameter is fabricated. Also an inert gas may be used as a foaming agent, which permits accomplishment of as high a foaming rate as 80%. Bubbles can be made finer if both an inorganic nucleus agent and organic nucleus agent are added to the foaming insulative resin.