Continuous purification method of sulfone polymer

Abstract

The invention relates to a continuous purification method of a sulfone polymer, and belongs to the field of post-treatment of high-molecular polymers. The method comprises the following steps: 1) centrifuging a sulfone-containing polymer suspension, removing a liquid phase from a solvent recovery system, feeding a solid phase into a purification device, washing and purifying under the action of a compound solvent and ultrasonic waves, and reducing residual monomers in the polymer to below 50ppm; and 2) carrying out multi-stage centrifugation-washing, sending the centrifuged solid phase into a leaching system, settling, contacting with desalted water to obtain a sulfone polymer material, reducing the concentrations of the organic solvent, the inorganic salt and the like to below 50ppm, mixing the sulfone polymer material with water, and sending the mixture into a subsequent polymer drying system. The method provided by the invention is simple in process and high in automation degree, greatly reduces the equipment investment and operation cost, saves the solvent and water, has low and stable residual monomer, solvent and inorganic salt content in the product, and has a wide application prospect as a post-treatment method for large-scale sulfone polymer purification / washing and the like.

Description

Technical Field

[0001] The invention relates to a continuous purification method for sulfone polymers, belonging to the field of post-treatment of organic high molecular polymers. Background Art

[0002] Sulfone polymer is a high-performance special engineering plastic, containing sulfone group (-SO2-) and arylene group in the molecular chain, mainly including common bisphenol A type polysulfone, polyaryl sulfone and polyether sulfone. Sulfone polymer has a high glass transition temperature and can be used for a long time at -180~175℃, with excellent mechanical properties, chemical corrosion resistance, aging resistance, etc. However, the macromolecular chain will gradually grow and precipitate, and will contain unreacted monomers, inorganic salts or solvents, etc., and their presence will greatly affect the subsequent resin processing and product application.

[0003] Patent CN213266352U introduces a sulfone polymer washing device, but the method has the following shortcomings: 1) The polymer material cannot be processed continuously, and the intermittent operation reduces the production efficiency, increases manual operation and complexity, and the quality is unstable; 2) Only water is used as a washing solvent, and it is difficult to reduce the water-insoluble residual monomers to the required index; 3) The primary washing water is evaporated and the steam is condensed, which consumes a lot of energy. At the same time, the patent also introduces a post-treatment method for washing sulfone resins, which uses ethanol purification and water washing, but does not consider solvent application and countercurrent washing. The amount of ethanol and washing water used is large (about 15 times that of the resin), and the cost is high. Patent CN115894921B uses compound solvents such as NMP, DMAC, acetonitrile, etc. for refining cyclic oligomers. The purification effect of unreacted residual monomers is poor, and the purification process is intermittent operation, which has low production efficiency. Summary of the invention

[0004] In order to solve the problems of high residual monophenyl / inorganic salt / solvent content, unstable quality, long time and low production efficiency, large amount of waste solvent and wastewater, etc. in the post-treatment of polysulfone in the prior art, the present invention innovatively proposes a continuous purification method for sulfone polymers. The whole process is completely continuous, and the residual monophenyl, inorganic salt and solvent in the obtained product are all less than 50ppm. The operation is simple, the degree of automation is high, the product quality is stable, and it has practical production significance.

[0005] The technical solution in the present invention is as follows:

[0006] A continuous purification method for a sulfone polymer comprises the following steps:

[0007] 1) The sulfone polymer suspension is separated in a centrifugal device, the liquid phase is desolventized and recovered, and the solid phase is sent to a purification device, where the solid phase is washed and purified with a compound solvent and ultrasound;

[0008] 2) After step 1) is completed, the material is sent to a centrifugal device, the liquid phase obtained by centrifugation is removed from the solvent recovery system, and the solid phase is sent to a leaching system, and qualified sulfone polymer material is obtained through sedimentation and desalted water leaching;

[0009] 3) The qualified sulfone polymer material is mixed with water and sent to the subsequent polymer drying system.

[0010] In the present invention, the sulfone-containing polymer suspension is a sulfone-containing polymer suspension obtained by polymerization reaction using a conventional one-step or two-step preparation process in the prior art. According to different preparation raw materials and processes, the residual monomers generally contained in the suspension include organic bisphenol compounds (such as bisphenol A, biphenol, bisphenol S, etc.), dichlorodiphenyl sulfone, etc., and residual inorganic salts such as salt-forming agents potassium carbonate or sodium carbonate.

[0011] In the present invention, the residual monomer content in the sulfone-containing polymer suspension is about 500-1500 ppm, the inorganic salt content is about 200-1500 ppm, the polymer content is about 20wt%-35wt%, and the rest is solvent.

[0012] Preferably, in step 1) of the present invention, the compound solvent is a mixture of water and at least one organic solvent selected from tetrahydrofuran, acetone, isopropanol and methyl acetate, wherein the concentration of the organic solvent in the compound solvent is 1wt%-30wt%, preferably 5wt%-20wt%, and the organic solvent concentration refers to the mass fraction of the organic solvent in the compound solvent to the total compound solvent.

[0013] Preferably, in step 1) of the present invention, the ultrasonic power density is 0.3-0.7w / cm 2 , preferably 0.4-0.6w / cm 2 , such as 0.4, 0.5, 0.6w / cm 2 ;

[0014] The temperature in the purification device in step 1) of the present invention is 50-150° C., preferably 50-100° C., more preferably 80-100° C.;

[0015] Preferably, the number of purification stages in step 1) of the present invention is adjusted according to the upstream reaction conditions and the requirements of the downstream products, preferably 2 to 6 stages, that is, the "centrifugation-washing" in step 1) is performed 2-6 times.

[0016] The solid phase obtained by the first centrifugation in step 1) of the present invention is a primary filter cake, preferably the moisture content of the primary filter cake is 50-70wt%, and the mass ratio of the composite solvent to the primary filter cake during each washing is (1.5-4):1, preferably (2.5-4):1; during each washing, the residence time of the material in the purification device is 0.5-5h, preferably 2-3h.

[0017] The liquid phase obtained by the centrifugal device of the present invention is mainly the organic solvent in the polymerization reaction process, which can be removed from the solvent recovery system and reused in the polymerization reaction process.

[0018] In a specific embodiment of the present invention, the purification device can be a purification tank, a purification tank, etc., and the purification device is accompanied by a stirring device. The stirring is turned on during the purification process to enhance the purification process; the centrifugal device can be a centrifuge, such as a horizontal spiral centrifuge.

[0019] Preferably, the rotation speed of the centrifugal device is 800-3000 r / min, which can be adjusted according to actual production.

[0020] The conditions of the centrifugation and purification devices in the aforementioned steps 1) and 2) of the present invention can be the same or different each time when repeated multiple times, and can be independently selected.

[0021] Preferably, after repeating step 1) "centrifugation-washing" multiple times, the residual monomers in the solid phase after centrifugation in step 2) are reduced to below 50 ppm, preferably below 20 ppm.

[0022] Preferably, the solid phase in step 2) of the present invention is sent to a leaching system, and the material is obtained through sedimentation and desalted water leaching. The specific scheme is: the solid phase is first sent to a sedimentation device for sedimentation, and the solid then enters a leacher, and is countercurrently contacted with multiple streams of desalted water for washing to obtain the material.

[0023] Specifically, the settling device includes a settling tower, a settling tank, a settling tank, etc. Any device that can achieve the purpose of settling can be used in the present invention. Washing water is added to the settling device, and the solid phase settles to the bottom of the device. The washing water overflows from the top of the settling device, so that the solid phase is initially in contact with the washing water, thereby controlling the settling time of the solid phase in the settling device to be 0.5-4h, preferably 2-3h.

[0024] Preferably, a plurality of baffles are provided in the sedimentation device, so as to make the solid phase flow regularly in the sedimentation device and prevent short circuit.

[0025] Specifically, the extractor is a spiral extractor, preferably a spiral conveyor, with a diameter of preferably 500-800 mm, a pitch of preferably 150-250 mm, a rotation speed of preferably 2-20 r / min, and a residence time of preferably 2.5-5 h;

[0026] Preferably, the extractor is installed at an angle, and the installation angle is preferably 15°-35°. The purpose of maintaining a small installation angle is to fill the equipment with liquid during leaching to reduce the adhesion of solid materials to the wall. When the machine is shut down, the materials are left by gravity, which is convenient for cleaning.

[0027] Preferably, the desalted water enters the extractor in multiple streams, preferably 2 to 5 streams; preferably, the mass ratio of the total amount of desalted water to the solid phase sulfone polymer in the extractor is 3 to 12:1, such as 4:1, 5:1, 8:1, 10:1, preferably 5-10:1.

[0028] Preferably, the temperature in the settling device and the extractor is 60-100°C, preferably 80-100°C.

[0029] Preferably, the concentrations of organic solvents and inorganic salts in the sulfone polymer after the continuous purification operation in steps 1) and 2) of the present invention are reduced to 50 ppm or less, and preferably the concentration of inorganic salts is reduced to less than 20 ppm.

[0030] Preferably, the qualified sulfone polymer material obtained after leaching in step 2) of the present invention is mixed with water to form a suspension and transported to the downstream through a pump for drying treatment; the concentration of the suspension is adjusted according to the needs of the downstream, preferably 10-30wt%, such as 20wt%.

[0031] Preferably, before the continuous purification method of the present invention is put into use, an inert gas, preferably nitrogen, is used to fully replace the entire purification system to remove the air inside the system.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention provides a method for purifying sulfone polymers continuously and on a large scale. The method adopts a continuous production scheme to ensure stable process conditions; overcomes the shortcomings of a traditional kettle-type intermittent purification / washing process, such as unstable quality, complex operation, long washing time, large amount of waste solvent and wastewater; and utilizes a compound solvent for washing, ultrasound, leaching and other means to make water and polymer contact in countercurrent to remove residual monomers, inorganic salts and solvents, so that their contents are all less than 50ppm, and the contents of inorganic salts and residual monomers are preferably less than 20ppm. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the process of continuously purifying sulfone polymers in Example 1 of the present invention; wherein, 1-a primary centrifuge, 2-a primary purification tank, 3-a secondary centrifuge, 4-a secondary purification tank, 5-a tertiary centrifuge, 6-a sedimentation tower, 7-an extractor, and 8-a water washing tank. DETAILED DESCRIPTION

[0035] Detection method of residual monomer and inorganic salt content:

[0036] Residual monomers: Instrument: Shimadzu LC20 AD XR, chromatographic column: Shim-pack Scepter HD-C18, test temperature: 40 degrees, mobile phase: 40% pure water / 60% acetonitrile, flow rate: 1 mL / min;

[0037] Inorganic salts: ICP-OES (inductively coupled plasma optical emission spectrometer);

[0038] Organic solvents: tested by gas chromatography.

[0039] Example 1

[0040] 400kg / h of sulfone polymer suspension from upstream, of which the polymer mass fraction is 25wt%, the total content of residual mono (dichlorodiphenyl sulfone, bisphenol A) is 1000ppm, the content of inorganic salt (potassium chloride) is 800ppm, and the rest is solvent. After the first-stage centrifuge, solid-liquid separation, liquid phase desolvent recovery system, the solid phase is the first-stage filter cake (mass 250kg / hr, wet content 60wt%), which flows by gravity into the first-stage purification tank, and the composite solvent of water, tetrahydrofuran and acetone (mass ratio 80:5:5) is injected into the first-stage purification tank at 800kg / h, the temperature is 80℃, the residence time is 2.5h, and the ultrasonic intensity is 0.5W / cm 2 The mixed liquid is continuously transported to the secondary centrifuge by a pump. After separation, the solid phase flows into the secondary purification tank by gravity. The liquid phase is desolventized and recovered. The flow rate of the compound solvent in the secondary purification tank is 1000 kg / h (water: tetrahydrofuran: acetone = 80:5:5), the temperature is 80 ° C, the residence time is 3 hours, and the ultrasonic intensity is 0.5 W / cm 2 After centrifugation, the total content of residual monomers in the solid phase filter cake was 17 ppm, and the content of inorganic salts was 26 ppm.

[0041] The filter cake flows to the sedimentation tower by gravity, and the sedimentation time is controlled for 2 hours. It is initially and fully contacted with the washing water at a temperature of 90°C. The solid phase polymer that settles to the bottom of the tower enters the extractor (screw conveyor), with an extraction temperature of 90°C, a rotation speed of 10r / min, an installation angle of 25°, and a residence time of 3 hours. Three streams of desalted water are added, with a flow rate of 200kg / h per stream. The solvent content in the solid phase sulfone polymer at the outlet of the extractor is 50ppm, the inorganic salt content is <10ppm, and the residual monomer is <10ppm. The qualified sulfone polymer is sent to the washing tank, configured into a 20wt% suspension, and transported to the downstream by a pump for drying treatment.

[0042] Example 2

[0043] 500kg / h of sulfone polymer suspension from upstream, polymer mass fraction 20wt%, total content of residual mono (dichlorodiphenyl sulfone, biphenyl diphenol) 800ppm, inorganic salt (potassium chloride) content 300ppm, the rest is solvent. After the first-stage centrifuge, solid-liquid separation, liquid phase desolvent recovery system, the solid first-stage filter cake (mass 250kg / h, wet content 60wt%) gravity flows into the first-stage purification tank, water and methyl acetate (mass ratio 85:15) composite solvent is injected into the purification tank at 900kg / h, temperature 90℃, residence time 2h, ultrasonic intensity 0.6W / cm2 The mixed liquid is continuously pumped to the secondary centrifuge through a pump, and after separation, it flows by gravity into the secondary purification tank. The compound solvent flow rate is 900 kg / h, the temperature is 90°C, the residence time is 2.5 hours, and the ultrasonic intensity is 0.6 W / cm 2 After centrifugation, the total content of residual monomers in the filter cake was 12 ppm, and the content of inorganic salts was 12 ppm.

[0044] The polymer filter cake flows by gravity to the sedimentation tower, and the sedimentation time is controlled to be 2.1 hours, and it is initially and fully contacted with the washing water at a temperature of 95°C. The polymer settled to the bottom of the tower enters the leaching device (screw conveyor), the leaching temperature is 95°C, the speed is 5r / min, the installation angle is 30°, and the residence time is 3.2 hours. Three streams of desalted water are added, and each flow rate is 300kg / hr. The solvent content in the solid-phase sulfone polymer at the outlet of the leaching device is 48ppm, the inorganic salt content is less than 10ppm, and the total residual monomer content is less than 10ppm. The qualified sulfone polymer is sent to the washing tank, configured into a 20wt% suspension and transported to the downstream by a pump for drying treatment.

[0045] Example 3

[0046] 300kg / hr of sulfone polymer suspension from upstream, 30wt% polymer mass fraction, 1200ppm total content of residual mono (dichlorodiphenyl sulfone, bisphenol S), 1500ppm inorganic salt (potassium chloride), and the rest is solvent. After the first-stage centrifuge, solid-liquid separation, liquid phase desolvent recovery system, the solid first-stage filter cake (mass 220kg / hr, wet content 60wt%) flows by gravity into the first-stage purification tank, and the water and isopropanol (mass ratio 80:20) compound solvent is injected into the purification tank at 600kg / h, the temperature is 90℃, the residence time is 2h, and the ultrasonic intensity is 0.6W / cm 2 The mixed liquid is continuously pumped to the secondary centrifuge through a pump, and after separation, it flows by gravity into the secondary purification tank. The compound solvent flow rate is 700kg / h, the temperature is 90℃, the residence time is 2.5h, and the ultrasonic intensity is 0.6W / cm 2 After centrifugation, the total content of residual monomers in the filter cake was 47 ppm and the content of inorganic salts was 27 ppm.

[0047] The polymer solid flows by gravity to the sedimentation tower, and the sedimentation time is controlled to be 2.7 hours. It is initially and fully contacted with the washing water at a temperature of 98°C. The polymer settled to the bottom of the tower enters the leaching device (screw conveyor), the leaching temperature is 98°C, the speed is 2r / min, the installation angle is 15°, and the residence time is 3.5 hours. Four streams of desalted water are added, with a flow rate of 200kg / h per stream. The solvent content in the solid-phase sulfone polymer at the outlet of the leaching device is 49ppm, the inorganic salt content is less than 10ppm, and the total residual monomer content is less than 20ppm. The qualified sulfone polymer is sent to the washing tank, configured into a 20wt% suspension, and pumped to the downstream for drying treatment.

[0048] Comparative Example 1

[0049] 500kg / hr of sulfone polymer suspension from upstream, polymer mass fraction 20wt%, total content of residual mono (dichlorodiphenyl sulfone, biphenyl disulfone phenol) 800ppm, inorganic salt (potassium chloride) content 300ppm, the rest is solvent, after a primary centrifuge, solid-liquid separation, liquid phase desolvent recovery system, solid phase primary filter cake (mass 250kg / hr, wet content 60wt%) gravity flow to a primary purification tank, water and N, N-dimethylformamide (mass ratio 85:15) composite solvent injected into the purification tank at 900kg / h, temperature 90℃, residence time 2h, ultrasonic intensity 0.6W / cm 2 The mixed liquid is continuously pumped to the secondary centrifuge through a pump, and after separation, it flows by gravity into the secondary purification tank. The compound solvent flow rate is 900 kg / h, the temperature is 90°C, the residence time is 2.5 hours, and the ultrasonic intensity is 0.6 W / cm 2 .

[0050] After centrifugation, the polymer solid filter cake flows by gravity to the sedimentation tower, and the sedimentation time is controlled to be 2.1 hours. It is initially and fully contacted with the washing water at a temperature of 95°C. The polymer settled to the bottom of the tower enters the extractor (screw conveyor), the extraction temperature is 95°C, the speed is 5r / min, the installation angle is 30°, and the residence time is 3.2 hours. Three streams of desalted water are added, and the flow rate of each stream is 300kg / hr. The solvent content of the solid sulfone polymer at the outlet of the extractor is 52ppm, the inorganic salt content is less than 20ppm, and the total residual monomer content is 65ppm.

[0051] Comparative Example 2

[0052] 300 kg / hr of sulfone polymer suspension from upstream, polymer mass fraction 30 wt%, total content of residual mono (dichlorodiphenyl sulfone, bisphenol S) 1200 ppm, inorganic salt (potassium chloride) content 1500 ppm, the rest is solvent, after a primary centrifuge, solid-liquid separation, liquid phase desolvent recovery system, filter cake (mass 220 kg / hr, wet content 60 wt%) gravity flow to a primary purification tank, water and isopropanol (mass ratio 80:20) composite solvent injected into the purification tank at 600 kg / h, temperature 90 ° C, residence time 2 hours, ultrasonic intensity 0.6 W / cm 2 The mixed liquid is continuously pumped to the secondary centrifuge through a pump, and after separation, it flows by gravity into the secondary purification tank. The compound solvent flow rate is 700kg / h, the temperature is 90℃, the residence time is 2.5h, and the ultrasonic intensity is 0.6W / cm 2 After centrifugation, the total content of residual monomers in the filter cake was 48 ppm and the content of inorganic salts was 70 ppm.

[0053] The filter cake was sent to a washing tank (pre-paved with 700 kg of desalted water), stirred and washed for 1 hour, and then centrifuged; the above washing and centrifugation operation was repeated three times. The solvent and inorganic salt contents in the polymer obtained by centrifugation were both greater than 60 ppm, and the product quality was unqualified.

[0054] The present invention provides a method for continuously purifying sulfone polymers, which solves the problems of multiple existing sulfone polymer purification / water washing equipment, complex operation, unstable product quality, unqualified residual orders, low production efficiency using intermittent operation, etc., greatly reduces equipment investment and operating costs, and is a very promising method for continuous purification of sulfone polymers.

[0055] The method and product of the present invention have been described through preferred embodiments, and relevant technicians can obviously modify or appropriately change and combine the method and product described herein without departing from the content, spirit and scope of the present invention to implement the technology of the present invention. It is particularly important to point out that all similar substitutions and modifications (such as appropriate adjustment of the amount of compound solvent added, purification stage, ultrasonic intensity, purification temperature and residence time, extractor length and water addition, temperature / residence time / desalted water amount and other conditions) are obvious to those skilled in the art, and they are all considered to be included in the spirit, scope and content of the present invention.

Claims

1. A method for continuous purification of a sulfone polymer, characterized in that: The following steps are involved: S1: The sulfone polymer suspension is separated in a centrifugal device, and the solid phase is sent to a purification device for washing and purification under the action of a compound solvent and ultrasound; S2: After step S1 is completed, the material is sent to a centrifugal device, and the solid phase obtained by centrifugation is sent to a leaching system, and a qualified sulfone polymer is obtained through sedimentation, leaching and washing.

2. The method according to claim 1, characterized in that In step S1, the selected compound solvent is a mixture of water and at least one organic solvent selected from tetrahydrofuran, acetone, isopropanol and methyl acetate; Preferably, the concentration of the organic solvent in the compound solvent is 1 wt%-30 wt%, preferably 5 wt%-20 wt%.

3. The method according to claim 1 or 2, characterized in that: In step S1: The ultrasound density of the ultrasound is 0.3-0.7W / cm 2 , preferably 0.4-0.6W / cm 2 ; Preferably, the temperature in the purification device is 50 to 150°C, preferably 50 to 100°C; Preferably, the centrifugation-washing operation in step S1 is repeated multiple times, preferably 2-6 times; Preferably, during each washing, the mass ratio of the composite solvent to the filter cake after washing is 1.5:1-4:1, preferably 2.5:1-4:1; Preferably, during each washing, the residence time of the solid phase in the purification device is 0.5 h to 5 h, preferably 2 to 3 h.

4. The method according to claim 1, characterized in that: In step S2, the solid phase obtained by centrifugation is first sent to a sedimentation device for sedimentation, and the solid phase obtained by sedimentation enters an extractor to be contacted with multiple streams of desalted water in countercurrent for washing to obtain a qualified sulfone polymer.

5. The method according to claim 4, characterized in that In step S2, the sedimentation time in the sedimentation device is 0.5-4h, preferably 2-3h; Preferably, the temperature in the settling device is 60-100°C, preferably 80-100°C.

6. The method according to claim 4, characterized in that In step S2, the residence time of the solid phase in the extractor is 2.5-5 hours, and the temperature in the extractor is 60-100° C., preferably 80-100° C.; Preferably, the extractor is installed at an inclination angle of 15°-35°; Preferably, the extractor is a screw conveyor having a diameter of 500 to 800 mm, a pitch of 150 to 250 mm, and a rotation speed of preferably 2 to 20 r / min.

7. The method according to claim 4 or 6, characterized in that: In step S2, the desalted water enters the extractor in multiple streams, preferably 2-5 streams; Preferably, the mass ratio of the total amount of desalted water to the solid phase of the sulfone polymer in the extractor is 3 to 12:1, preferably 5 to 10:1; Preferably, the temperature in the extractor is 60-100°C, preferably 80-100°C.

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