To obtain a releasing agent securing an excellent heat retaining property and releasability and reducing the generation of a harmful gas as much as possible by containing a specified weight ratio of a powder talc and a boric acid respectively and mixing the both constituents in the powdered state via a rotary container type mixer.
By wt., 50-90% powder talc as a main constituent and 10-50% boric acid as an organic binder bond are contained in a powder releasing agent, both constituents are sufficiently mixed and fine grains of the boric acid are uniformly coated on the surface of the powder talc. A mechanical mixer such as a rotary cylinder type mixer of a ball mill type mixer, etc., or a mechanical mixer of a centrifugal fluidizing crusher, etc., is used to sufficiently stir and mix in the mixing method. Since the melting point of the boric acid is low, the boric acid is soften or melted when coming into contact with a high temp. of the die and is acted as a binder bond between the talc and the surface of the mold or among the talc. When the boric acid is heated at ≥300°C, it is changed into a boric oxide, but no gas owing to burning is discharged in the changing process.
ADACHI MITSURU
TAKASHIMA MASAHIKO
