| 摘要 |
PURPOSE:To produce a molded polyolefin foam which has a high expansion ratio and suffers little deformation at ordinary temperature. CONSTITUTION:A polyolefin resin is subjected to extrusion foaming using a foaming agent which is either a liquid mixture composed of at least two compounds selected from the group (A) consisting of ethers, esters, ketones, and saturated hydrocarbons each having a boiling point of 100 deg.C or lower or a liquid mixture composed of at least one compound selected from the group (A) and at least one compound selected from the group consisting of ethers, esters, ketones, saturated hydrocarbons, and alcohols each having a boiling point of 100-150 deg.C. The foam thus produced has a high expansion ratio but suffers little deformation, so that it is less apt to be crushed even when it has been shaped so as to have a small diameter. The foaming agent can be precisely supplied because it is liquid. This process is suited for the production of a foam-insulated electric wire to be used in a high-speed signal transmission cable, an under-carpet cable, etc. |
