| 摘要 |
PURPOSE:To manufacture the titled sheet in a short time efficiently by a method wherein the sheet is heated quickly in an infrared heating furnace until foaming begins and is heated slowly in a hot air heating furnace after foaming has begun. CONSTITUTION:Until foaming begins, a foaming thermoplastic resin sheet (ex; sheet composed of polyethylene etc., foaming agent like diazocarbonamide etc. and crosslinking agent like dicumyl peroxide etc.) is heated in an infrared heating furnace in which a radiating plate is provided to generate infrared rays and said radiating plate is higher in temperature than a hot air heating furnace and which is slightly lower in temperature in both edge parts along the longitudinal direction than in the central part and from the beginning of foaming until the end thereof said sheet is heated in the hot air heating furnace. |
