| 摘要 |
PROBLEM TO BE SOLVED: To obtain a molding material which is safe and forms uniform foams, substantially consisting of tannic acid and a thermoplastic resin. SOLUTION: This material substantially consists of, desirably, 1-8 wt.% tannic acid and, desirably, 92-99 wt.% thermoplastic resin (e.g. PS). Namely, a heat decomposition gas of tannic acid harmless to the human body is utilized. Further, it is desirable that the tannic acid is used in admixture with sodium hydrogencarbonate. Namely, the combined use of sodium hydrogencarbonate can enhance a foaming ratio. In this case, the molding material substantially consists of 1-8 wt.% tannic acid/sodium hydrogen carbonate mixture and 92-99 wt.% thermoplastic resin. It is desirable that the sodium hydrogencarbonate is used in an amount of 75 wt.% or below based on the tannic acid/sodium hydrogen carbonate. The thermoplastic resin is exemplified by a polyolefin such as a polyethylene or a polypropylene, a polyester, or a styrene resin. |
