A separation and purification system and process for polyether ether ketone

Abstract

The present application relates to the technical field of polymer separation and purification, and particularly relates to a separation and purification system and process for polyether ether ketone. The present application discloses a separation and purification system for polyether ether ketone, comprising a separation tower, which is sequentially provided with an extraction water washing section, a liquid holding section and a rectification section from bottom to top; further comprising an extraction liquid storage tank, a first reboiler, a separation tower condenser and a reflux tank, the extraction water washing section, the extraction liquid storage tank and the first reboiler are connected in series to form an extraction circulation loop, the extraction water washing section, the first reboiler, the liquid holding section, the rectification section, the separation tower condenser and the reflux tank are connected in series to form an evaporation circulation loop; further comprising a water washing liquid storage tank, a second reboiler and a side tower condenser connected in series with the extraction water washing section to form a water washing circulation loop; a circulating pump is arranged on each loop. The equipment can realize semi-continuous operation of polyether ether ketone separation and purification, reduce the frequency of material transfer, simplify the process, improve work efficiency, and facilitate industrialization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polymer separation and purification, and particularly relates to a separation and purification system and process for polyether ether ketone. BACKGROUND

[0002] Polyether ether ketone (PEEK) is a high polymer composed of repeating units containing a ketone bond and two ether bonds in the main chain structure, and belongs to a special high polymer material. PEEK is synthesized from 4,4'-difluorobenzophenone, hydroquinone and potassium carbonate as raw materials, and diphenyl sulfone as a solvent. The material has physical and chemical properties such as high temperature resistance and chemical drug corrosion resistance, and is a kind of semi-crystalline high polymer material. It can be used as a high-temperature structural material and an electrical insulating material, and can be compounded with glass fibers or carbon fibers to prepare reinforced materials, which have a large number of applications in the fields of aerospace, medical devices and industry.

[0003] If a higher purity PEEK needs to be prepared, the dissolved diphenyl sulfone solvent and NaF salt in PEEK need to be separated. However, the melting point and boiling point of PEEK are extremely high, and PEEK cannot be purified by distillation. The existing technology adopts a process method of extracting and dissolving diphenyl sulfone, and washing NaF with water. Since PEEK is a solid, it is difficult to transport between different separation equipment. Generally, the PEEK recovery process is completed in a reaction kettle.

[0004] The existing PEEK purification process is that the PEEK-diphenyl sulfone mixed solid is put into the reaction kettle through a manhole, and the extraction process of diphenyl sulfone is first performed. Acetone is used as an extractant, and acetone is added to the kettle. Diphenyl sulfone needs to be extracted multiple times. On the one hand, it is necessary to ensure that the diphenyl sulfone content in the extracted acetone is high, so as to facilitate the separation of diphenyl sulfone and acetone in the later stage, and on the other hand, it is necessary to ensure that PEEK does not contain diphenyl sulfone, so as to improve the purity of PEEK. The diphenyl sulfone content in the acetone in the later stage of extraction is low, and the acetone needs to be evaporated in an evaporation kettle. The acetone without diphenyl sulfone evaporated can be used as an extractant to extract diphenyl sulfone again until PEEK no longer contains diphenyl sulfone. The second stage is the process of washing acetone and NaF with water, that is, fresh water is added to the reaction kettle to dissolve the remaining acetone and NaF salt in PEEK. The water washing process also needs to be performed multiple times. The acetone and NaF-containing aqueous solution after extraction also needs to be evaporated through a distillation device to evaporate the acetone, and the water addition amount also needs to be controlled to increase the NaF content in the aqueous solution and reduce the waste water evaporation amount in the later stage. The PEEK solid without diphenyl sulfone and NaF is discharged from the bottom of the reaction kettle after the water washing is completed.

[0005] From the above processing procedure, it can be seen that the reaction kettle is used as the PEEK purification equipment, the discontinuity of the processing technology itself leads to the cumbersome switching of the operation procedure, more supporting equipment is needed, and the limitation of the kettle type equipment further reduces the purification efficiency of PEEK during the processing of a single procedure. If the factory wants to expand production, it can only be realized by increasing the number of reaction kettles, and the effect of expansion is very unsatisfactory. SUMMARY

[0006] The present application solves the technical problem in the prior art that the PEEK purification process can only be operated intermittently by the reaction kettle, and other related acetone recovery and NaF water evaporation equipment need to be configured, which not only has a large number of equipment, but also has an intermittent operation mode, low processing efficiency and inconvenience for industrialization.

[0007] The first aspect of the present application provides a separation and purification system for polyether ether ketone, which is used for the separation of polyether ether ketone, diphenyl sulfone and NaF, and comprises a separation tower, which is sequentially provided with an extraction water washing section, a liquid holding section and a rectification section from bottom to top.

[0008] The separation and purification system further comprises an extraction liquid storage tank, a first reboiler, a separation tower condenser and a reflux tank, the extraction water washing section, the extraction liquid storage tank and the first reboiler are sequentially connected in series to form an extraction circulation loop, and the extraction water washing section, the first reboiler, the liquid holding section, the rectification section, the separation tower condenser and the reflux tank are sequentially connected in series to form an evaporation circulation loop.

[0009] The separation and purification system further comprises a water washing liquid storage tank, a second reboiler and a side tower condenser which form a water washing circulation loop in series with the extraction water washing section.

[0010] The extraction circulation loop, the evaporation circulation loop and the water washing circulation loop are respectively provided with a first circulation pump, a second circulation pump and a third circulation pump.

[0011] Further, the first circulation pump is arranged between the extraction liquid storage tank and the first reboiler, and the flow control of the first circulation pump is 5-100 m 3 / h.

[0012] Further, the top of the extraction water system section is provided with a distributor.

[0013] Further, the separation tower condenser comprises a separation tower first condenser and a separation tower second condenser which are connected in series, and the outlets of the separation tower first condenser and the separation tower second condenser are connected with the reflux tank.

[0014] Further, the second circulation pump is arranged between the reflux tank and the rectification section.

[0015] Further, the third circulating pump is arranged between the water washing liquid storage tank and the second reboiler.

[0016] The second aspect of the present application provides a separation and purification process using the separation and purification system for polyether ether ketone.

[0017] (1) Extraction: the polyether ether ketone to be separated and purified is placed in the separation tower, and an extractant is added to the extraction water washing section to extract diphenyl sulfone, the extractant and the diphenyl sulfone flow into the extract liquid storage tank by itself, and part of the extractant in the extract liquid storage tank is heated and circulated in the extraction circulation loop by the first circulating pump;

[0018] (2) Extractant evaporation: the extractant is added again, and the mixture of the extractant and the diphenyl sulfone is heated and vaporized in the first reboiler by the first circulating pump, and then enters the liquid holding section to realize gas-liquid separation, the gas phase is condensed to obtain condensed liquid by the separation tower condenser, and part of the condensed liquid returns to the separation tower;

[0019] (3) Water washing: ultrapure water containing the extractant and NaF flows into the water washing liquid storage tank by itself, and is heated and warmed in the second reboiler by the third circulating pump, and then returns to the extraction water washing section after being condensed by the auxiliary tower condenser.

[0020] Further, in step (1), the liquid level height of the extractant in the extraction water washing section is controlled to be constant.

[0021] Further, in step (2), the condensed liquid flows into the reflux tank by itself, part of the condensed liquid returns to the top of the separation tower as reflux liquid by the second circulating pump, part of the condensed liquid returns to the extraction water washing section of the separation tower, and the remaining condensed liquid is recovered.

[0022] Further, when the content of diphenyl sulfone in the polyether ether ketone is less than 50 ppm, step (2) is ended; when the content of NaF in the polyether ether ketone is less than 50 ppm, step (3) is ended.

[0023] Compared with the prior art, the present application has the following technical effects:

[0024] The application provides a new PEEK (polyether ether ketone) post-processing device and process, which can change the original PEEK processing process from batch to semi-continuous operation. The PEEK separation and purification device is a PEEK three-in-one processing tower, which integrates the processes of extraction of the extraction agent (acetone), evaporation of the extraction agent (acetone) and water washing of the extraction agent (acetone) and NaF into one, reduces the frequency of transferring PEEK solid materials between different processes, simplifies the operation process procedure, thereby reducing the difficulty of material transfer and the difficulty of process operation, and improving the work efficiency. On the other hand, the new separation and purification device designed by the application can significantly increase the PEEK processing capacity without increasing the number of devices, the device is convenient for industrialization amplification, has the capacity of scale production, and effectively reduces the equipment investment cost required by plant expansion. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A process flow diagram of the separation and purification system of the embodiment of the application is shown.

[0026] Figure 2 A zoomed-in view of the A part of the middle part is shown. Figure 1

[0027] Reference signs:

[0028] 1, separation tower; 2, extraction and water washing section; 3, liquid holding section; 4, rectification section; 5, extraction liquid storage tank; 6, first reboiler; 7, first-stage condenser of the separation tower; 8, second-stage condenser of the separation tower; 9, reflux tank; 10, water washing liquid storage tank; 11, second reboiler; 12, condenser of the auxiliary tower; 13, first circulating pump; 14, second circulating pump; 15, third circulating pump; 16, distributor; 17, auxiliary tower; 18, liquid outlet. DETAILED DESCRIPTION

[0029] The following will describe the embodiments of the application by specific examples, and those skilled in the art can easily understand other advantages and effects of the application from the disclosure. Although the description of the application will be introduced in combination with the preferred embodiments, this does not mean that the features of the application are limited to the embodiments. On the contrary, the purpose of introducing the application in combination with the embodiments is to cover other options or modifications that can be extended based on the claims of the application. In order to provide a deep understanding of the application, many specific details will be included in the following description. The application can also be implemented without using these details. In addition, in order to avoid confusion or obscure the focus of the application, some specific details will be omitted in the description. It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other without conflict.

[0030] Reference is made to Figures 1-2 ​The separation and purification system for polyether ether ketone of the present application is used for realizing the separation of polyether ether ketone and diphenyl sulfone, NaF, and comprises a separation tower 1, which is sequentially provided with an extraction water washing section 2, a liquid holding section 3 and a rectification section 4 from bottom to top.

[0031] The separation and purification system further comprises an extraction liquid storage tank 5, a first circulating pump 13, a first reboiler 6, a separation tower condenser, a reflux tank 9 and a second circulating pump 14, wherein the extraction water washing section 2, the extraction liquid storage tank 5, the first circulating pump 13 and the first reboiler 6 are sequentially connected in series to form an extraction circulation loop, and the extraction water washing section 2, the first reboiler 6, the liquid holding section 3, the rectification section 4, the separation tower condenser and the reflux tank 9 are sequentially connected in series to form an evaporation circulation loop.

[0032] The separation and purification system further comprises a water washing liquid storage tank 10, a third circulating pump 15 and a second reboiler 11, which form a water washing circulation loop in series with the extraction water washing section 2.

[0033] Both polyether ether ketone (PEEK) and diphenyl sulfone are high-melting-point substances and are in solid state at normal temperature, but PEEK has a certain granularity and cannot be dissolved by acetone or water, diphenyl sulfone is easily dissolved in acetone, and NaF is not easily dissolved in acetone but is easily dissolved in water. Based on the above-mentioned dissolution characteristics, acetone is used as an extractant to extract diphenyl sulfone, and then water is used as a solvent to dissolve NaF and residual acetone.

[0034] Firstly, the PEEK solid to be separated and purified is delivered to the extraction water washing section 2 of the PEEK three-in-one treatment tower-separation tower 1 through the charging port by pneumatic conveying, and then the operation of introducing acetone to extract diphenyl sulfone is started: the acetone continuously enters the extraction water washing section 2 to completely soak the PEEK solid to be separated and purified, so as to realize the extraction and separation of diphenyl sulfone therein, the valve opening degree of the liquid outlet 18 of the extraction water washing section 2 is controlled to control the liquid outflow amount of the acetone-diphenyl sulfone mixture after extraction, and the continuous addition amount of acetone is controlled in the light of the fact that the liquid level height of acetone in the extraction water washing section 2 is maintained constant.

[0035] The acetone-diphenyl sulfone mixture flows to the extraction liquid storage tank 5 through the liquid outlet 18, and then part of the extractant acetone flows to the first reboiler 6 under the action of the first circulating pump 13 to be re-heated and forced to circulate and flow in the extraction circulation loop, so as to maintain a certain extraction temperature in the extraction water washing section 2 and ensure the smooth progress of the extraction reaction, the remaining acetone mixed solution containing diphenyl sulfone in the extraction liquid storage tank 5 is continuously taken out to realize the separation of PEEK solid and diphenyl sulfone, and a dynamic balance is maintained among the continuously taken-out acetone mixed solution containing diphenyl sulfone, the acetone reciprocally flowing between the first reboiler 6 and the extraction water washing section 2 and the newly added acetone, so as to maintain the stability of the liquid level in the extraction water washing section 2.

[0036] The diphenyl sulfone content in the acetone mixed solution is maintained at a high concentration, and the diphenyl phenol concentration is 10%-80% of the concentration of the acetone-diphenyl phenol mixed solution. As the extraction process proceeds, the diphenyl sulfone content in the PEEK is continuously reduced. In this process, in order to maintain a high diphenyl sulfone concentration in the acetone, the acetone inlet flow rate and the diphenyl sulfone-containing acetone mixed solution outlet flow rate can be reduced, or the acetone can be intermittently introduced and the diphenyl sulfone-containing acetone mixed solution can be intermittently discharged.

[0037] Optionally, the flow control of the first circulating pump 13 is 5-100 m 3 / h, by increasing the flow of the first circulating pump 13, the mixing degree of acetone and PEEK-diphenyl sulfone in the extraction water washing section 2 is promoted, and the mixing and extraction effect is improved.

[0038] Optionally, the acetone entering the extraction water washing section 2 adopts a tangent inlet form, so that the acetone liquid forms a cyclone flow form, further increasing the turbulent effect of the PEEK solid, promoting the mixing degree of acetone and PEEK-diphenyl sulfone in the extraction water washing section 2, and improving the mixing and extraction effect.

[0039] Optionally, the separation column 1 side wall of the extraction water washing section 2 is provided with a nitrogen gas inlet, and nitrogen gas is introduced into the bottom of the extraction water washing section 2, promoting the rolling of the PEEK, thereby helping the diphenyl sulfone embedded between the PEEK to be dissolved by the acetone.

[0040] Optionally, the top of the extraction water washing section 2 is provided with a distributor 16 for continuous addition of acetone.

[0041] Optionally, the liquid outlet 18 is provided with a wire mesh for intercepting PEEK solids to prevent the PEEK solids in the extraction water washing section 2 from flowing into the extraction liquid storage tank 5.

[0042] When the extraction process is finished, the content of diphenyl sulfone in PEEK is low, and it is difficult to separate diphenyl sulfone completely by extraction, at this time, the evaporation process of the extraction agent acetone is changed: fresh acetone is used to continuously elute PEEK in the extraction water washing section 2, and the acetone-diphenyl sulfone mixture after elution is transferred to the first reboiler 6 by the first circulating pump 13 for heating and vaporization, and the vaporized mixture enters the liquid holding section 3 and realizes gas-liquid separation, wherein the liquid phase enters the extraction water washing section 2 downward by gravity, and the gas phase spontaneously enters the rectification section 4 upward, and the condensed liquid-acetone after condensation in the separation tower condenser flows into the reflux tank 9, under the action of the second circulating pump 14, part of the condensed liquid (acetone) returns to the top of the separation tower 1 as reflux liquid to continue to play the effect of rectification, which is used to ensure the purity of acetone at the top, part of the condensed liquid (acetone) returns to the extraction water washing section 2 of the separation tower 1 to elute PEEK again, and the acetone used for elution after rectification treatment does not contain diphenyl sulfone, so as to ensure that PEEK does not contain diphenyl sulfone, and the remaining condensed liquid in the reflux tank 9 which does not return to the separation tower 1 is used as production liquid.

[0043] In the acetone evaporation process, part of the diphenyl sulfone in the extraction water washing section will enter the liquid holding section 3 with acetone due to heating and vaporization, and the diphenyl sulfone in the gaseous mixture is separated from acetone by the rectification effect of the rectification section 4.

[0044] Optionally, the separation tower condenser comprises a separation tower first condenser 7 and a separation tower second condenser 8 arranged in series, and the outlets of the separation tower first condenser 7 and the separation tower second condenser 8 are connected with the reflux tank 9.

[0045] With the progress of the acetone evaporation process, the content of diphenyl sulfone in PEEK continues to decrease, and the content of diphenyl sulfone in the extraction liquid storage tank 5 continues to increase, when the content of diphenyl sulfone in the extraction liquid storage tank 5 increases to a certain content, the acetone-diphenyl sulfone mixture is intermittently transferred out.

[0046] Optionally, when the content of diphenyl sulfone in PEEK decreases to less than 50 ppm, the acetone evaporation process is stopped.

[0047] When the acetone evaporation process is completed, the PEEK no longer contains diphenyl sulfone, at which point the subsequent ultrapure water washing operation is performed: ultrapure water is continuously introduced into the PEEK crude product in the extraction water washing section 2, the ultrapure water can wash away the residual acetone therein and dissolve a small amount of NaF contained in the PEEK. The acetone and NaF-containing ultrapure water after washing flows by itself to the water washing liquid storage tank 10, and then is transferred to the second reboiler 11 by the third circulating pump 15 for heating and temperature rising vaporization. The vaporized mixture of acetone and water enters the auxiliary column 17, the gaseous phase part is condensed by the auxiliary column condenser 12 of the auxiliary column 17, and then part of the condensed liquid returns to the extraction water washing section 2 for continuous water washing, and then flows by itself to the water washing liquid storage tank 10. The acetone-water mixture is collected at the top of the auxiliary column 17, and the NaF aqueous solution without acetone is intermittently collected from the water washing liquid storage tank 10. If the NaF content in the water washing liquid storage tank 10 is low, the water is collected by evaporation to increase the NaF concentration in the NaF aqueous solution.

[0048] Optionally, when the NaF content in the PEEK is reduced to less than 50 ppm, the ultrapure water washing process is stopped.

[0049] After the above separation and purification process is completed, the PEEK crude product no longer contains acetone, and the contents of diphenyl sulfone and NaF can be reduced to less than 50 ppm. The ultrapure water is discharged from the extraction water washing section 2, and the bottom discharge valve of the extraction water washing section 2 is opened, so that the PEEK product with higher purity is discharged to the outside of the equipment by gravity.

[0050] The separation and purification process for polyether ether ketone of the present application avoids the mixing of water into the acetone extraction process and the acetone evaporation process, because the acetone extraction process and the acetone evaporation process do not contain water, while the ultrapure water washing process contains water. Different rectifying columns, reboilers, and supporting condensers and temporary storage tanks are designed for the above operations.

[0051] The present application proposes a new PEEK separation and purification process, which replaces the intermittent operation mode in the prior art with a semi-continuous operation mode (different processes are switched to intermittent operation, and the same process can be operated continuously), which can effectively improve the PEEK purification processing efficiency:

[0052] (1) The acetone extraction process can be operated continuously, and fresh acetone is continuously introduced into the separation column to achieve extraction of a higher content of diphenyl sulfone. The acetone solution containing diphenyl sulfone after extraction can be continuously collected from the separation column;

[0053] (2) The acetone evaporation process can be operated continuously, fresh acetone is continuously introduced into the separation column to achieve extraction with a lower content of diphenyl sulfone, and is heated and evaporated. Part of the acetone without diphenyl sulfone is continuously collected at the top of the separation column, and part of the acetone continuously returns to the separation column to continue participating in the extraction process;

[0054] (3) The water washing-acetone and NaF process can also be operated continuously, and the ultrapure water can be continuously introduced into the separation tower, and the acetone-water mixture can be continuously taken out from the auxiliary tower.

[0055] The application designs a new PEEK separation and purification equipment, which can realize the three stages of acetone extraction, acetone evaporation, water washing-acetone and NaF in the same set of equipment, and has high equipment integration degree. In addition, since the equipment is configured with an external heater and a condenser, the heating, evaporation and condensation efficiency can be significantly improved, so that the yield can be easily increased, and the industrialization can be easily enlarged.

[0056] The single set of equipment of the application can realize the PEEK purification process with different processing requirements, without increasing or decreasing the number of equipment, but only by changing the equipment parameters of the application.

[0057] The above only describes the preferred embodiments of the application, and is not intended to limit the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A separation and purification system for polyetheretherketone (PEEK), used for the separation of PEEK from diphenyl sulfone and NaF, characterized in that, The separation and purification system includes a separation tower, which is provided from bottom to top with an extraction and washing section, a liquid holding section and a distillation section; The separation and purification system also includes an extract liquid storage tank, a first reboiler, a separation tower condenser, and a reflux tank. The extraction washing section, the extract liquid storage tank, and the first reboiler are connected in series to form an extraction circulation loop. The extraction washing section, the first reboiler, the liquid holding section, the rectification section, the separation tower condenser, and the reflux tank are connected in series to form an evaporation circulation loop. The separation and purification system also includes a washing liquid storage tank connected in series with the extraction washing section to form a washing circulation loop, a second reboiler, and a secondary tower condenser. The extraction circulation loop, evaporation circulation loop, and water washing circulation loop are respectively equipped with a first circulation pump, a second circulation pump, and a third circulation pump.

2. The separation and purification system for polyether ether ketone according to claim 1, characterized in that, The first circulating pump is located between the extract storage tank and the first reboiler, and the flow rate of the first circulating pump is controlled to be 5-100 m³ / h. 3 / h.

3. The separation and purification system for polyether ether ketone according to claim 1, characterized in that, A distributor is provided at the top of the extraction and washing section.

4. The separation and purification system for polyether ether ketone according to claim 1, characterized in that, The separation tower condenser includes a primary separation tower condenser and a secondary separation tower condenser connected in series. The outlets of both the primary and secondary separation tower condensers are connected to a reflux tank.

5. The separation and purification system for polyether ether ketone according to claim 1, characterized in that, The second circulation pump is located between the reflux tank and the rectification section.

6. The separation and purification system for polyether ether ketone according to claim 1, characterized in that, The third circulation pump is located between the washing liquid storage tank and the second reboiler.

7. A separation and purification process using the separation and purification system for polyether ether ketone according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Extraction: The polyether ether ketone to be separated and purified is placed in the separation tower, and an extractant is added to the extraction washing section to extract diphenyl sulfone. The extractant and diphenyl sulfone flow by gravity to the extraction liquid storage tank. Part of the extractant in the extraction liquid storage tank is heated and circulated in the extraction circulation loop by the first circulation pump. (2) Extractant evaporation: The extractant is added again. The mixture of extractant and diphenyl sulfone enters the first reboiler through the first circulation pump and is heated and vaporized. Then it enters the liquid holding section to achieve gas-liquid separation. The gas phase is condensed by the condenser of the separation tower to obtain condensate. Part of the condensate is returned to the separation tower. (3) Water washing: Ultrapure water is continuously added to the extraction water washing section. The ultrapure water containing extractant and NaF flows by gravity to the water washing liquid storage tank. After being heated by the third circulation pump, it enters the second reboiler and is condensed by the auxiliary tower condenser before flowing back to the extraction water washing section.

8. The separation and purification process according to claim 7, characterized in that, In step (1), during the extraction and washing section, the liquid level of the extractant is controlled to remain constant.

9. The separation and purification process according to claim 7, characterized in that, In step (2), the condensate flows by gravity to the reflux tank, a portion of the condensate is returned to the top of the separation tower as reflux liquid via the second circulation pump, a portion of the condensate is returned to the extraction and washing section of the separation tower, and the remaining condensate is collected.

10. The separation and purification process according to claim 7, characterized in that, Step (2) ends when the diphenyl sulfone content in polyether ether ketone is less than 50 ppm; step (3) ends when the NaF content in polyether ether ketone is less than 50 ppm.

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