To provide a method which is a simplified process for removing the residual volatiles from an SPS powder and by which the volatiles such as an unreacted monomer can be removed at good efficiency without encountering a trouble i.e., the deposition of powder on the equipment.
In removing the residual volatiles from a mainly syndiotactic styrenic polymer (SPS) by passing it through a drier, the drying is performed at a drying temperature of 200°C or below (170°C or below when the SPS is a styrene/p-methylstyrene copolymer containing at least 3mol% repeating p- methylstyrene units) and at a pressure inside the drier of below 760mmHg to a liquid content (the weight of the volatiles×100/the total weight of the powder containing the volatiles) of 20wt.% or below, and optionally continued at a temperature equal to or below the melting point of the styrene polymer powder. The drier used is a jacketed grooved one.
HIROSE KENJI
BABA SHUZO
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