Method for forming a low viscosity polyarylene sulfide

Patent metadata

Field	Value
Publication number	US-9809681-B2
Application number	US-201615045296-A
Country	US
Kind code	B2
Filing date	Feb 17, 2016
Priority date	Feb 19, 2015
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

A method for washing a polyarylene sulfide with a washing solution that contains a carefully controlled solvent content is provided. More particularly, the washing solution typically contains water (e.g., deionized water) in an amount of from about 30 wt. % to about 70 wt. % and an aprotic organic solvent in an amount of from about 30 wt. % to about 70 wt. %. Within such carefully controlled ranges, the present inventors have discovered that the polyarylene sulfide can retain a relatively high oligomer content, which in turn, helps minimize the melt viscosity.

First claim

What is claimed is:

1. A method for forming a washed polyarylene sulfide, the method comprising contacting a slurry of a polyarylene sulfide with a washing solution within a vessel in which the slurry of the polyarylene sulfide enters the vessel at a slurry inlet that is located such that solids of the slurry flow via a gravity flow from the slurry inlet to a solids outlet and in which the washing solution enters the vessel at a liquid inlet and flows counter current to the gravity flow of the solids to a liquid outlet that is above the slurry inlet, wherein the washing solution contains from about 30 wt. % to about 70 wt % of water and from about 30 wt. % to about 70 wt. % of an aprotic organic solvent, wherein the washed polyarylene sulfide has an oligomer content of from about 0.5 wt. % to about 2 wt. % and a melt viscosity of about 2,350 poise or less, as determined in accordance with ISO Test No. 11443:2005 at a shear rate of 1200 s −1 and at a temperature of 310° C.

2. The method of claim 1 , wherein the aprotic organic solvent is N-methylpyrrolidone.

3. The method of claim 1 , wherein the washing solution has a pH level of from about 8.0 to about 13.5.

4. The method of claim 1 , wherein the washing solution is generally free of acetone.

5. The method of claim 1 , wherein the washing solution is at a temperature of from about 15° C. to about 120° C.

6. The method of claim 1 , wherein the slurry of the polyarylene sulfide is contacted with the washing solution within a sedimentation column.

7. The method of claim 1 , wherein the washed polyarylene sulfide has an oligomer content of from about 1.2 wt. % to about 1.6 wt. %.

8. The method of claim 1 , wherein the washed polyarylene sulfide has a melt viscosity of from about 1,000 to about 2,280 poise, as determined in accordance with ISO Test No. 11443:2005 at a shear rate of 1200 s −1 and at a temperature of 310° C.

9. The method of claim 1 , wherein the washed polyarylene sulfide has a crystallization temperature of about 200° C. or less.

10. The method of claim 1 , wherein the washed polyarylene sulfide has a polydispersity index of about 4.3 or less.

11. The method of claim 10 , wherein the washed polyarylene sulfide has a weight average molecular weight of from about 30,000 to about 60,000 Daltons.

12. The method of claim 10 wherein the washed polyarylene sulfide has a number average molecular weight of from about 8,000 about 12,500 Daltons.

13. The method of claim 1 , wherein the washed polyarylene sulfide is a linear polyphenylene sulfide.

14. The method of claim 1 , further comprising contacting the washed polyarylene sulfide with an additional washing solution.

15. The method of claim 14 , wherein the additional washing solution contains water.

16. The method of claim 1 , further comprising drying the washed polyarylene sulfide after contact with the washing solution.

17. The method of claim 14 , wherein the washed polyarylene sulfide is further contacted with the additional washing solution in a second vessel in which the washed polyarylene sulfide flows via gravity flow counter current to the additional washing solution.

18. The method of claim 17 , wherein the additional washing solution is fed to the second vessel from a third vessel, the washed polyarylene sulfide being further contacted with the additional washing solution in the third vessel.

Assignees

• Ticona Llc

Inventors

• Nekkanti Venkata M
• Chiong Hendrich A
• Grayson Jacob

Classifications

• B01D11/0288 Primary

  Applications, solvents · CPC title

• B01D21/02

  Settling tanks {with single outlets for the separated liquid} · CPC title

• C08G75/14 Primary

  Polysulfides · CPC title

• C08G85/002

  Post-polymerisation treatment · CPC title