| 摘要 |
PROBLEM TO BE SOLVED: To suppress blushing of the vicinity of a gate occurring at the time of injection molding a polyethylene naphthalene dicarboxylate by using a die obtained by constituting at least one of a gate block and a cavity wall surface near the gate of a material having a heat insulation of a specific value or less of a thermal conductivity. SOLUTION: A die obtained by constituting at least one of a gate block and a cavity wall surface near a gate of a material (heat insulation material) having a heat insulation of 1 kcal/m.hr. deg.C or less of thermal conductivity is used. This heat insulation material member is formed of a three-dimensional stereo lithographic system by using a photo-setting resin or the like. A polyethylene naphthalene dicarboxylate(PEN) is injection molded by using the die of this constitution. Here, the PEN is a polyester containing a naphthalene dicarboxylic acid as a main acid component and an ethylene glycol as a main diol component. Thus, blushing near the gate occurring when the PEN is injection molded can be reduced. |
