A method for forming a polyarylene sulfide is described. The method can include a multi-step cooling and precipitation process in which the cooling rate of the solution that carries the polymer is decreased during a portion of the overall cooling. This slower cooling period can encompass at least a portion of the period during which the polymer precipitates from the solution. The precipitation process can form polyarylene sulfide particles with good particle integrity and a narrow particle size distribution, which can reduce fines and improve downstream processing and final product characteristics.

A method for forming a polyarylene sulfide is described. The method can include a multi-step cooling and precipitation process in which the cooling rate of the solution that carries the polymer is decreased during a portion of the overall cooling. This slower cooling period can encompass at least a portion of the period during which the polymer precipitates from the solution. The precipitation process can form polyarylene sulfide particles with good particle integrity and a narrow particle size distribution, which can reduce fines and improve downstream processing and final product characteristics.

Methods and systems are provided for recovering an organic solvent from a waste sludge generated during formation of a polyarylene sulfide. Methods include combining the waste sludge with a liquid extractant that extracts the organic solvent into a homogeneous liquid phase. Upon a temperature change, the homogeneous liquid phase can separate into an organic solvent-rich liquid phase and a liquid extractant-rich liquid phase. The two liquid phases can be separated and further processed if desired to further purify the recovered organic solvent. Methods can also include forming the polyarylene sulfide by a polymerization process and thereafter purifying a slurry of the polyarylene sulfide. A liquid washing product is formed as a result of the purification process, which can be subjected to a distillation process that forms an organic solvent-rich stream and the waste sludge.

Methods and systems are provided for recovering an organic solvent from a waste sludge generated during formation of a polyarylene sulfide. Methods include combining the waste sludge with a liquid extractant that extracts the organic solvent into a homogeneous liquid phase. Upon a temperature change, the homogeneous liquid phase can separate into an organic solvent-rich liquid phase and a liquid extractant-rich liquid phase. The two liquid phases can be separated and further processed if desired to further purify the recovered organic solvent. Methods can also include forming the polyarylene sulfide by a polymerization process and thereafter purifying a slurry of the polyarylene sulfide. A liquid washing product is formed as a result of the purification process, which can be subjected to a distillation process that forms an organic solvent-rich stream and the waste sludge.

Methods and systems are provided for recovering an organic solvent from a waste sludge generated during formation of a polyarylene sulfide. Methods include combining the waste sludge with an anti-solvent to create a dispersion, which includes a solid phase that includes a substantial portion of the impurities of the polyarylene sulfide formation and a liquid phase that contains the anti-solvent and organic solvent employed during formation of the polyarylene sulfide. The liquid phase is separated from the solid phase and then subjected to a distillation process to separate the organic solvent from the anti-solvent. Methods can also include forming the polyarylene sulfide by a polymerization process and thereafter purifying a slurry of the polyarylene sulfide. A liquid washing product is formed as a result of the purification process, which can be subjected to a distillation process that forms an organic solvent-rich stream and the waste sludge.

Methods and systems are provided for recovering an organic solvent from a waste sludge generated during formation of a polyarylene sulfide. Methods include combining the waste sludge with an anti-solvent to create a dispersion, which includes a solid phase that includes a substantial portion of the impurities of the polyarylene sulfide formation and a liquid phase that contains the anti-solvent and organic solvent employed during formation of the polyarylene sulfide. The liquid phase is separated from the solid phase and then subjected to a distillation process to separate the organic solvent from the anti-solvent. Methods can also include forming the polyarylene sulfide by a polymerization process and thereafter purifying a slurry of the polyarylene sulfide. A liquid washing product is formed as a result of the purification process, which can be subjected to a distillation process that forms an organic solvent-rich stream and the waste sludge.

To provide a method of manufacturing polyarylene sulfide (PAS) while efficiently recovering an organic amide solvent at a low energy cost, without using an organic solvent, from washing wastewater produced by washing a raw material mixture containing PAS and an organic amide solvent using a solvent containing water; a method of manufacturing PAS by reducing the amount of water supplied when washing the raw material mixture using a solvent containing water; and PAS manufactured by these methods. A method according to the present invention includes: a step of mixing a solvent containing water and a raw material mixture that contains PAS and an organic amide solvent, and then washing the PAS; a step of obtaining a separated liquid by solid-liquid separation; and a step of separating the separated liquid into distilled vapor having a smaller amount of the organic amide solvent and a recovered liquid having a larger amount of the organic amide solvent by heating, where the heating is performed utilizing an increase in temperature based on compressing the distilled vapor and/or compressing a heat medium heat-exchanged with the distilled vapor.

To provide a method of manufacturing polyarylene sulfide (PAS) while efficiently recovering an organic amide solvent at a low energy cost, without using an organic solvent, from washing wastewater produced by washing a raw material mixture containing PAS and an organic amide solvent using a solvent containing water; a method of manufacturing PAS by reducing the amount of water supplied when washing the raw material mixture using a solvent containing water; and PAS manufactured by these methods. A method according to the present invention includes: a step of mixing a solvent containing water and a raw material mixture that contains PAS and an organic amide solvent, and then washing the PAS; a step of obtaining a separated liquid by solid-liquid separation; and a step of separating the separated liquid into distilled vapor having a smaller amount of the organic amide solvent and a recovered liquid having a larger amount of the organic amide solvent by heating, where the heating is performed utilizing an increase in temperature based on compressing the distilled vapor and/or compressing a heat medium heat-exchanged with the distilled vapor.

Provided is a method for manufacturing fine polyarylene sulfide (PAS) powder, in which impurities such as alkali metal salts and/or PAS oligomers are reduced while the wettability of the fine PAS powder in a fine PAS powder-containing solid is retained after solid-liquid separation of a separation liquid obtained by subjecting a dispersion liquid containing granular PAS to separation into granular PAS and a separation liquid; and a fine PAS powder. The method for manufacturing a fine PAS powder of the present invention includes: (a) separating granular PAS and a separation liquid from a dispersion liquid containing granular PAS, by solid-liquid separation using at least one screen that has an opening diameter of 75 to 180 m; (b) performing solid-liquid separation of the separation liquid to obtain a fine PAS powder-containing solid; (c) heating the fine PAS powder-containing solid to reduce an amount of an organic solvent to obtain a wet cake; and (d) washing the wet cake using an aqueous solvent. The water content of the wet cake after heating is at least 30 wt. %.

Provided is a method for manufacturing fine polyarylene sulfide (PAS) powder, in which impurities such as alkali metal salts and/or PAS oligomers are reduced while the wettability of the fine PAS powder in a fine PAS powder-containing solid is retained after solid-liquid separation of a separation liquid obtained by subjecting a dispersion liquid containing granular PAS to separation into granular PAS and a separation liquid; and a fine PAS powder. The method for manufacturing a fine PAS powder of the present invention includes: (a) separating granular PAS and a separation liquid from a dispersion liquid containing granular PAS, by solid-liquid separation using at least one screen that has an opening diameter of 75 to 180 m; (b) performing solid-liquid separation of the separation liquid to obtain a fine PAS powder-containing solid; (c) heating the fine PAS powder-containing solid to reduce an amount of an organic solvent to obtain a wet cake; and (d) washing the wet cake using an aqueous solvent. The water content of the wet cake after heating is at least 30 wt. %.