| 摘要 |
PROBLEM TO BE SOLVED: To reduce the possibility of producing a harmful substance when used or discarded with excellent transparency by precooling a sheet-like material obtained by extruding a polypropylene resin in a molten state to a temperature from a crystallizing temperature to lower than a melting point of the resin, and then immediately quenching it to a specific temperature or lower. SOLUTION: After a sheet-like material extruded from a T-die 1 is precooled to a temperature from a crystallizing temperature to lower than a melting point of a raw material polypropylene resin by a cooling roll 2 so that solidification of molten resin is not excessively proceeded with the result that its quenching effect may not become small, the material is immediately quenched to 30 deg.C or below to solidify the material. In this cooling, a generator 4 of a forcible cooling water flow having a water tank including a linear nozzle at its lower end is, for example, provided to generate cooling water flows flowing to both surfaces of the sheet, the sheet is more forcibly cooled, and maintained until the sheet becomes therein to 30 deg.C or below. Thus, a harmful substance is eliminated when used or discarded with excellent transparency. |
