PURPOSE: To prepare a molding material for resin mold motors, giving a motor with high electrical characteristics and little burr formation and having excellent moldability, by commpounding an unsaturated polyester resin with a fibrous reinforcing material, a thickener and a specific filler.
CONSTITUTION: (A) An unsaturated polyester resin is mixed with (B) calcium carbonate filler wherein pref. 80wt% thereof has particle size of 1W10μ (C), an inorganic filler, e.g. sand, etc., having larger particle size than (B), preferably the particle size of 103W105m, (D) a fibrous reinforcing material, e.g. short glass fibers, etc. and (E) preferably 0.1W15wt% of a thickener, e.g. silica fine powder, etc., to give the desired molding compound having a viscosity of 102W105cp at room temperature (25°C) and at a curing temperature.
EFFECT: The crack resistance and the mechanical properties of the molding articles are excellent.