| 摘要 |
PURPOSE:To obtain particles having a high bulk density and a uniform particle size in good efficiency, by kneading a methylene chloride solution of polycarbonate which does not gel upon concentration in a kneader having a grinding mechanism and holding hot water. CONSTITUTION:First, hot water of a temperature higher than the b.p. of methylene chloride is poured into the barrel of a kneader. While this water is kept at a predetermined temperature by heating through a jacket, a methylene chloride solution of a polycarbonate is added in small portions to the barrel. As soon as this solution is added, the boiling and vaporization of the methylene chloride rapidly occurs and the mixture is brought to a state of a paste or cake containing a large number of bubbles and water drops. As the addition of the polycarbonate solution and the vaporization of the methylene chloride proceed, the contents slowly lose viscousness and form cake-like matter of a high consistency. At this time, the hot water is discharged, and the desolventation of the contents is continued, while the temperature in the kneader is being kept at a temperature higher than the b.p. of methylene chloride. During this period, the cake-like mixture is ground by a shearing action between each blade of the kneader and the inside wall of the kneader to form particles of a uniform particle diameter. |
