BINDING COMPOSITION FOR USE IN INJECTION OR EXTRUSION MOLDING OF METAL OR CERAMIC POWDER

PURPOSE: To improve the fluidity at a molding time and to enable the perfect removal in a short time by using a binder consisting of a molten plasticizer and a softening agent of a specific ratio such as PVAc of specific molecular weight and similar polyethylene glycol. CONSTITUTION: This composition contains, by weight, 30-90% PVAc of 35,000-1,000,000 average molecular weight and 10-70% a molten plasticizer and a softening agent for PVAc selected from the following compositions (a)-(c): the composition (a) may be present in a mixture together with the composition (b) or (c) or the quantity of (b) or (c) is made to 5-30% to the total quantity of the binder composition where the composition (a) is polyethylene glycol(PEG) of 500-50,000 average molecular weight, the composition (b) is aliphatic polyester of a pre-polymer consisting of adipic acid and PEG of 2,000-20,000 average molecular weight and the composition (c) is a copolymer making hydroxy as an end group and consisting of ethylene oxide and propylene oxide of 2,000-20,000 average molecular weight.