Toshiharu Goto

Recycling of silane cross-linked polyethylene for insulation of cables by supercritical alcohol

Thermoplasticization of silane cross-linked polyethylene for insulation of wires and cables was studied. For material recycling of cross-linked polyethylene, it is favorable to make it thermoplastic. We successfully obtained thermoplastic polyethylene from silane cross-linked polyethylene by using chemical reaction in supercritical alcohol. Mechanical and electrical properties of recycled polyethylene were good enough for insulation. Common antioxidant for polyethylene is effective for protection against the aging of recycled polyethylene. Therefore, closed recycling of silane cross-linked polyethylene will possibly be accomplish.

Recycling of insulation of 600V XLPE cable using supercritical alcohol

We introduce the technology to make silane cross-linked polyethylene (Si-XLPE) thermoplastic using supercritical alcohol for material recycling of Si-XLPE. The new continuous process was developed using extruder for the treatment of supercritical fluid for industrialization. We successfully obtained recycled PE at the rate of 20 kg/h. The gel fraction of recycled PE was 0%, and its mechanical properties were similar to virgin PE. It means that siloxane bond was selectively decomposed. Then, 100% recycled PE was applied for the insulation of 600 V XLPE cable. The properties of the recycled cable satisfied JIS C 3605, the Japanese Industrial Standards of 600 V XLPE insulated cable. These results indicated that this technology can be applicable to the cable to cable recycling. Moreover, it was calculated that CO2 emission can be reduced by this technology in comparison with virgin PE.