Process and apparatus for precipitation of poly (phenylene ether)

1. A process for precipitating polyphenylene ether, the process comprising

introducing an anti-solvent to a mechanically stirred vessel containing a polyphenylene ether solution comprising a polyphenylene ether and a solvent to provide a mixture, wherein the polyphenylene ether solution comprises the polyphenylene ether in an amount of up to 15 weight percent;

agitating the mixture under conditions effective to provide precipitated polyphenylene ether particles having a bulk density of 150 to 500 kg/m 3 ; and recovering the precipitated polyphenylene ether particles.

2. The process of claim 1 , wherein the anti-solvent comprises methanol, ethanol, isopropanol, n-butanol, acetone, methyl ethyl ketone, or a combination comprising at least one of the foregoing.

3. A process for precipitating polyphenylene ether, the process comprising

introducing an anti-solvent to a mechanically stirred vessel comprising a polyphenylene ether solution comprising a polyphenylene ether and a solvent to provide a mixture comprising a precipitated polyphenylene ether, wherein the polyphenylene ether solution comprises the polyphenylene ether in an amount of up to 15 weight percent;

wherein introducing the anti-solvent comprises

adding a first amount of the anti-solvent effective to provide a volume ratio of solvent to anti-solvent of 60:40 to 80:20, and agitating the slurry for 10 to 90 minutes;

adding a second amount of the anti-solvent effective to provide a volume ratio of solvent to anti-solvent of 35:65 to 55:45, and agitating the slurry for 10 to 90 minutes; and

adding a third amount of the anti-solvent effective to provide a volume ratio of solvent to anti-solvent of 10:90 to 30:70, and agitating the slurry for 30 to 90 minutes; and

recovering precipitated polyphenylene ether particles having a bulk density of 150 to 500 kg/m 3 .

4. The process of claim 3 , wherein the anti-solvent comprises methanol, ethanol, isopropanol, n-butanol, acetone, methyl ethyl ketone, or a combination comprising at least one of the foregoing.

5. The process of claim 1 , wherein the polyphenylene ether is a poly(2,6-dimethyl-1,4-phenylene ether) having an intrinsic viscosity of 0.30 to 1.60 deciliter per gram, determined by Ubbelohde viscometer at 25° C. in chloroform.

6. The process of claim 1 , wherein the solvent comprises toluene, benzene, xylene, or a combination comprising at least one of the foregoing.

7. The process of claim 1 , wherein the polyphenylene ether solution is maintained at a temperature of 30 to 75° C.

8. A process for precipitating polyphenylene ether, the process comprising

introducing a polyphenylene ether solution comprising

a polyphenylene ether, and

a solvent

to a first feed tube equipped with an atomizer positioned at an outlet of the first feed tube, wherein the first feed tube is surrounded by a second feed tube configured to provide a first anti-solvent comprising water;

atomizing the polyphenylene ether solution to provide an atomized polyphenylene ether solution;

contacting the atomized polyphenylene ether solution with an anti-solvent to provide a slurry comprising a precipitated polyphenylene ether; and

recovering the precipitated polyphenylene ether;

wherein the precipitated polyphenylene ether is in the form of polyphenylene ether particles having a bulk density of 150 to 500 kg/m 3 .

9. The process of claim 8 , wherein the outlet of the first feed tube is located at an end of a third feed tube configured to provide a second anti-solvent.

10. The process of claim 8 further comprising introducing the slurry to a mechanically stirred vessel.

11. The process of claim 8 , wherein the outlet of the first feed tube is located in an impeller zone of a mechanically stirred vessel, wherein the mechanically stirred vessel comprises a second anti-solvent.

12. The process of claim 8 , wherein contacting the polyphenylene ether solution and the first anti-solvent forms a combined stream having a temperature of 30 to 75° C.

13. The process of claim 8 , wherein the atomizer is a pressure-swirl single-fluid atomizer, a pressure-swirl two-fluid atomizer, a high pressure orifice atomizer, or a sonication-assisted atomizer.

14. A system for precipitating polyphenylene ether comprising:

a first feed tube 10 equipped with an atomizer 12 and having a polyphenylene ether solution stream 36 comprising a polyphenylene ether and a solvent;

a second feed tube 14 surrounding the first feed tube having a first anti-solvent stream 38 , wherein the first anti-solvent stream is configured to contact the polyphenylene ether solution stream upon discharge from the first feed tube;

a third feed tube 16 having a second anti-solvent stream 40 , and configured to receive an outlet stream from the first and second feed tubes;

a mechanically stirred vessel 20 downstream of the third feed tube, wherein the mechanically stirred vessel is configured to receive an outlet stream from the third feed tube, wherein the outlet stream from the third feed tube comprises polyphenylene ether particles;

a condenser 24 configured to receive vaporized liquid from the mechanically stirred vessel; and

a filter 22 configured to receive an outlet stream from the mechanically stirred vessel, wherein the filter is configured to recover polyphenylene ether particles having a bulk density of 150 to 500 kg/m 3 .

15. A system for precipitating polyphenylene ether comprising:

a first feed tube 26 equipped with an atomizer 28 and having a polyphenylene ether solution stream 42 comprising a polyphenylene ether and a solvent;

a second feed tube 30 surrounding the first feed tube having a first anti-solvent stream 44 , wherein the first anti-solvent stream is configured to contact the polyphenylene ether solution stream upon discharge from the first feed tube;

a mechanically stirred vessel 34 , wherein the mechanically stirred vessel is configured to receive an outlet stream from the first and second feed tubes, wherein the outlet stream comprises polyphenylene ether particles having a bulk density of 150 to 500 kg/m 3 .