POLYSTYRENE RESIN FOAM AND EXPENDABLE PROTOTYPE FOR FULL MOLD CASTING METHOD CONSISTING OF THIS RESIN

摘要

PURPOSE:To produce a full mold casting which is free from a casting defect, surface roughening, etc., by defective evaporation and is better particularly in the product appearance than in the case of use of a PMMA foam. CONSTITUTION:This polystyrene foam consists of polystyrene, poly-alpha- methylstyrene and carbon black and this expandable prototype for the full mold casting method consists of this foam. More preferably the foam contains 2 to 20 pts.wt. poly-A-methylstyrene and 0.01 to 2.0 pts.wt. carbon black per 100 pts.wt. polystyrene. As a result, the foam has the extremely high gasification efficiency in a temp. region when the foam is heated by the radiation heat of molten metal and is better in expending by evaporation than in the case of the PMMA foam. In addition, the foam is as equally inexpensive as general- purpose PS foams and is extremely advantageous as the material of the expendable prototype for the full mold casting method.