PURPOSE: To obtain a core material which is excellent in heat resistance and flow property, and is used in particular for manufacturing a fine injection molded product by using a water soluble high polymer having a hydroxyl group in the core material to be used within a metallic mold for injection molding.
CONSTITUTION: The degree of saponification of the core material is suitably controlled to 70 to 95 mol%. The Tg thereof is preferably 00 to 100°C and is measured with a differential thermal scanning calorimeter. Further, the melt index thereof is preferably 0.1 to 50 (210°C and 2160 g load condition as ASTM D-1238). Besides, the water soluble high polymer, suitably the specified amount of oxazoline compound is properly added to improve the flow property and water solubility. Further, for improvement in the flow property, a 0.1-5 pts.wt. polyhydric alcohol compound may be added to the 100 pts.wt. water soluble high polymer. Furthermore, for improvement in the heat resistance, suitably a 1-200 pts.wt. filler having 0.1-200 μm grain size is added to the 100 pts.wt. water soluble high polymer.
HATTORI JIRO
TORIGOE SHINJI
