| 摘要 |
PROBLEM TO BE SOLVED: To provide a technique for alleviating inconvenience of dimensional variations of a molded sheet due to post-molding heating.SOLUTION: A sheet molding method includes a step of melt-extruding a thermoplastic resin in a sheet shape from a die 10 of an extrusion molder, and then cooling and solidifying the same by passage between a pair of cooling rolls 30. An average strain rate d&egr;/dt[sec] calculated by (Formula) d&egr;/dt=(V1/Z)ln(V1/V0) and a frequency ω[sec], which is a reciprocal of a relaxation time of the thermoplastic resin calculated by using a storage modulus (G') and a loss modulus (G") of the thermoplastic resin, satisfy a relation of d&egr;/dt<ωat a temperature of a resin sheet 30 at a center between the die 10 and the cooling rolls 30. Furthermore, V0 is a speed of the thermoplastic resin extruded from the extrusion molder [mm sec]; V1 is a speed of collecting the sheet-shaped thermoplastic resin [mm sec]; and Z is an air gap [mm] between the die and the cooling rolls. |
