Patent ID: 7342088

Claim:
A method for precipitating polyphenylene ether by mixing a polyphenylene ether solution comprising polyphenylene ether and a good solvent therefor with a poor solvent for polyphenylene ether to precipitate polyphenylene ether particles, the method comprising: using a precipitation tank equipped with (a) a draft tube, (b) an at least one-stage stirring blade disposed in the draft tube and selected from an inclined paddle blade, a screw blade and a ribbon blade, (c) one or more baffles disposed on the outside of the draft tube, (d) a solution supply port, (e) a poor solvent supply port and (f) an exhaust port; adding, to a mixed solution comprising the good solvent, the poor solvent and polyphenylene ether particles and circularly flowing by rotation of the stirring blade (b), the polyphenylene ether solution from the solution supply port (d) and concurrently a poor solvent from the poor solvent supply port (e), thereby precipitating polyphenylene ether particles; and discharging and recovering the precipitated polyphenylene ether particles together with the mixed solution from the exhaust port (f).