| 摘要 |
PURPOSE: To obtain a powdery CaO antifoamer added to a rubber, a plastic or the like and improved in storage stability, an antifoaming effect, etc., by using a specified amount of MgO and specifying the BET specific surface area, the mean particle diameter, etc. CONSTITUTION: This antifoamer is the one prepared by adding 5-20% MgO to a powdery CaO-based antifoamer added to a rubber or plastic composition and having a BET specific surface area of 1-5m<2> /g and a mean particle diameter of about 5μm or below. Because the added MgO can suitably suppress the hygroscopicity CaO, the hygroscopicity of the powdery antifoamer in air can be decreased. When the antifoamer is added to a rubber or plastic composition, it exhibits good microdispersibility and uniformly lowers the moisture present in the composition. Therefore, it can exhibit an excellent antifoaming effect in molding a rubber or plastic composition and can give a rubber or plastic molding excellent in surface smoothness.
|
