PURPOSE: To manufacture a pattern for lost foam casting obtaining a casting without remaining carbon on the surface by impregnating foaming agent into a suspending material having a grain of a specific diameter of a specific copolymer polycarbonate and forming after aging beads of a specific density obtd. by pre-expanding.
CONSTITUTION: The copolymer polycarbonate in the general formulas of the formula I and the formula II, is selected and formed to the grain having 100-1000 μdiameter. In the formulars, (n) is 3, 4 or 5, (x) is 100-450 and number average molecular wt. is 15,000-100,000 having 85-130°C single glass transition temp. Successively, this grain is suspended in the water by using, a suitable suspending agent series and a suitable foaming agent is added to the suspending material, and heated and impregnated into the grain, and after separating the impregnated beads from the water suspending solution, the beads are washed and dried. The beads are exposed to steam in the air and pre-expanded, and after forming to about 0.016 - about 0.064 g/cm3, the aging is applied and the beads are formed to a desirable pattern having ≤ about 0.048 g/cm3 density.
HEIBUN ESU KESURINGU JIYUNIYAA
FUSHIANGUNINGU SAN
