A heterogeneous tubular cation exchange membrane, its preparation method and application

Abstract

This invention provides a heterogeneous tubular cation exchange membrane, its preparation method, and its application. The preparation method of the heterogeneous tubular cation exchange membrane includes: (1) mixing cation resin powder, binder, softener, stabilizer, and antioxidant to obtain agglomerated ion exchange material; (2) extruding the obtained agglomerated ion exchange material to obtain the heterogeneous tubular cation exchange membrane. The preparation method has simple overall operation steps and can prepare a heterogeneous tubular cation exchange membrane with a smaller inner diameter of the mold tube while ensuring that the tube wall remains unchanged. This is beneficial to improving the packing density of the membrane module and has important research significance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of exchange membrane, and particularly relates to a heterogeneous tubular cation exchange membrane and a preparation method and application thereof. BACKGROUND

[0002] The development of ion exchange membrane can be traced back to 70 years ago, and it is also the earliest membrane developed in China. At present, it has developed from laboratory research to application in different industries. In recent years, with the continuous attention of the state to environmental protection, processes based on ion exchange membranes have a crucial position in environmental protection, clean production and separation because they can realize the directional or selective migration of ions.

[0003] The preparation methods of heterogeneous cation exchange membrane are as follows: one is hot pressing method: the cation exchange resin powder and additives such as binder, softener and stabilizer are mixed by mixing or internal mixing, and then hot pressed into a film under suitable pressure and temperature. For example, CN102553454A discloses a preparation method of heterogeneous cation exchange membrane, which mainly solves the technical problems of "run-off" and "water entry" caused by too low water permeation time, high salt diffusion coefficient and complex processing process of the existing ordinary heterogeneous cation exchange membrane. The method comprises: drying the resin to a water content of 4-8%, and then grinding the dried resin powder; mixing silane cross-linked polyethylene and polyisobutylene in a proportioning mixer, then adding ion exchange resin powder, calcium stearate and antioxidant in a proportioning manner, and continuing mixing until the mixture is uniformly mixed, and then discharging; first drawing thick film pieces from an open mill, then drawing thin film pieces from the open mill, and then cutting; attaching polyester mesh cloth on the upper and lower surfaces of the film pieces, and then putting them into a tablet press, and finally sending them into the hot pressing area of the tablet press to be hot pressed into a shape, and then taking out the product after cooling.

[0004] The second is melt extrusion method: the cation exchange resin powder and additives such as binder, softener and stabilizer are mixed by mixing or internal mixing, and then heated to a suitable temperature to form a semi-liquid state, and then extruded into a film.

[0005] Thirdly, the casting method: the binder is dissolved into a solution in a solvent, and then the cation exchange resin powder and additives are added and mixed, and finally the cation exchange membrane is obtained by casting and evaporating the solvent. For example, CN104078691A discloses a preparation method of a high water-absorbing proton exchange membrane, which comprises the following steps: (1) mixing hollow mesoporous silica microspheres and fluorine type perfluorosulfonic acid polymer in a mass ratio of 1:9-99 to obtain a mixture; (2) melting and extruding the mixture obtained in step (1) into a film by using an extruder, the casting head temperature is 180-200℃, the screw rotation speed is 20-35r / min, and the roller speed is 60-100cm / min; (3) soaking the film obtained in step (2) in a 0.1-1wt% sodium hydroxide solution for 4-12 hours, the soaking temperature is 60-80℃, to obtain a sodium type perfluorosulfonic acid film; (4) soaking the sodium type perfluorosulfonic acid film obtained in step (3) in a 0.1-1wt% hydrochloric acid solution for 1-6 hours, the soaking temperature is 20-30℃, and then washing with deionized water to obtain a high water-absorbing proton exchange membrane. Compared with the solution casting method, the high water-absorbing proton exchange membrane prepared by the invention has higher electrical conductivity and mechanical strength.

[0006] Fourthly, the casting polymerization method: the cation exchange resin powder is dispersed in a partially polymerized binder solution, and then the final polymerization process is completed by the casting method to obtain the cation exchange membrane. For example, CN102863636A discloses a method for preparing a fluorine-containing polyarylether composite cation exchange membrane by in-situ polymerization, which comprises the following steps: dissolving a fluorine-substituted polyarylether cation polymer in a suitable solvent, adding an appropriate amount of inorganic nano-powder, active composite components and catalyst to obtain a membrane preparation solution, removing the solvent by heat treatment, and in-situ polymerization of the active composite components and cross-linking reaction with the fluorine-substituted polyarylether during the membrane preparation process to obtain a fluorine-containing polyarylether composite cation exchange membrane material. This method can effectively solve the swelling problem of the membrane material, and the prepared cation polymer electrolyte membrane has good dimensional stability, mechanical strength, ion conductivity and low vanadium ion permeability, and has important application value in the fields of all-vanadium redox flow batteries, polymer electrolyte membrane fuel cells, direct methanol fuel cells, ion exchange resins, membrane separation, sensors, etc.

[0007] However, existing ion exchange membranes are mainly flat-sheet membranes, with membrane modules using a plate-and-frame structure. Flat-sheet membrane devices are bulky, have a small effective contact area, low exchange capacity, and cannot handle high-solids-content feed solutions. Furthermore, using flat-sheet membranes increases the difficulty of equipment installation and maintenance; if one membrane is damaged, the entire device must be disassembled, replaced, and reassembled. Therefore, inspired by pressure-driven membranes (microfiltration, ultrafiltration), the concept of preparing tubular cation exchange membranes was proposed. Tubular ion exchange membranes have the following characteristics: they can handle complex feed solutions (such as those containing calcium salt precipitates, colloids, polysaccharides, large molecular proteins, cell debris, etc.), and do not require pretreatment processes such as microfiltration or ultrafiltration when handling general feed solutions; the membrane surface has a long flow path, which can promote ion diffusion and ion migration processes; the feed flow rate can be adjusted over a wide range, effectively controlling concentration polarization and fouling; the membrane has a self-supporting structure, eliminating the need for additional supports, making module assembly relatively easy; the device is small and simple in structure, allowing for the fabrication of small, lightweight devices. The tubular ion exchange membrane prepared by the existing technology is mainly made by rolling and bonding flat ion exchange membranes into semi-finished tubular ion exchange membranes, and then using a strip heater to press and heat seal the semi-finished tubular ion exchange membrane at the sealing point. However, the defects of this method are: (1) it cannot produce small-diameter tubular membranes, which leads to low membrane module packing density; (2) during heat sealing, the force at the sealing point is uneven, which easily leads to local unbonded phenomena; (3) the membrane is easily damaged by excessively high temperature during heat sealing.

[0008] Therefore, providing a method for preparing heterogeneous tubular cation exchange membranes with smaller diameters and less susceptibility to breakage is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide a heterogeneous tubular cation exchange membrane, its preparation method, and its application. The preparation method first involves mixing raw materials to obtain agglomerated ion exchange materials; then, the obtained agglomerated ion exchange materials are added to an extruder for extrusion to obtain the heterogeneous tubular cation exchange membrane. The preparation method is simple to operate and the resulting heterogeneous tubular cation exchange membrane has a small inner diameter, making it suitable for preparing high-density membrane modules and possessing significant research value.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] In a first aspect, the present invention provides a method for preparing a heterogeneous tubular cation exchange membrane, the method comprising the following steps:

[0012] (1) The cation exchanger, binder, softener, stabilizer and antioxidant are mixed to obtain agglomerated ion exchanger;

[0013] (2) The clump-shaped ion exchanger obtained in step (1) is added to an extruder and extruded to obtain the heterogeneous tubular cation exchange membrane.

[0014] The method for preparing heterogeneous tubular cation exchange membrane provided by the present invention firstly involves mixing the raw materials, and then directly extruding the resulting agglomerated ion exchange material to obtain a tubular cation exchange membrane. The preparation method is simple to operate and does not require heat sealing and bonding. This avoids the problems of uneven stress at the sealing point during heat sealing and bonding, which can easily lead to local unbonded phenomena, and the membrane being easily damaged due to excessively high temperature during heat sealing, which are common problems in tubular membranes obtained by first preparing sheet membranes and then winding them into tubes.

[0015] The heterogeneous tubular cation exchange membrane obtained by the preparation method provided by the present invention is tubular in shape, and the length of the tube can be adjusted according to equipment requirements. In particular, ultra-long tubular membranes can be prepared. Moreover, the inner diameter of the heterogeneous tubular cation exchange membrane prepared by the preparation method can be as low as 1 mm, which can be used to prepare membrane modules with high packing density, which has important research significance.

[0016] Preferably, the clump-shaped ion exchanger in step (1) comprises the following components by weight: 20-25 parts by weight of binder, 65-75 parts by weight of cation resin powder, 4-5 parts by weight of softener, 1-2.5 parts by weight of stabilizer and 0.5-1 parts by weight of antioxidant.

[0017] The adhesive can be 21 parts by weight, 21.5 parts by weight, 22 parts by weight, 22.5 parts by weight, 23 parts by weight, 23.5 parts by weight, 24 parts by weight, or 25 parts by weight, etc.

[0018] The cationic resin can be in quantities of 65 parts by weight, 66 parts by weight, 67 parts by weight, 68 parts by weight, 69 parts by weight, 70 parts by weight, 71 parts by weight, 72 parts by weight, 73 parts by weight, or 74 parts by weight, etc.

[0019] The softening agent may be 4.1 parts by weight, 4.2 parts by weight, 4.3 parts by weight, 4.4 parts by weight, 4.5 parts by weight, 4.6 parts by weight, 4.7 parts by weight, 4.8 parts by weight, or 4.9 parts by weight, etc.

[0020] The stabilizer may be 1.2 parts by weight, 1.4 parts by weight, 1.6 parts by weight, 1.8 parts by weight, 2 parts by weight, 2.1 parts by weight, 2.2 parts by weight, 2.3 parts by weight, or 2.4 parts by weight, etc.

[0021] The antioxidant may be present in amounts of 0.55 parts by weight, 0.6 parts by weight, 0.65 parts by weight, 0.7 parts by weight, 0.75 parts by weight, 0.8 parts by weight, 0.85 parts by weight, 0.9 parts by weight, or 0.95 parts by weight.

[0022] Preferably, the softening agent in step (1) comprises polyisobutylene.

[0023] Preferably, the stabilizer in step (1) comprises calcium stearate.

[0024] Preferably, the adhesive in step (1) comprises any one or a combination of at least two of polyethylene, polypropylene, or polyvinyl chloride.

[0025] Preferably, the cationic resin powder in step (1) includes any one or a combination of at least two of the following: 201×7 type resin powder, 201×4 type resin powder, D201 type resin powder, D202 type resin powder or D301 type resin powder.

[0026] Preferably, the antioxidant in step (1) includes any one or a combination of at least two of antioxidants 1010, 1076, 168 or TNP.

[0027] Preferably, the mixing method in step (1) is intensive mixing.

[0028] The internal mixer selected for internal mixing can include commercially available Guangdong Lina internal mixers or Dongguan Changfeng internal mixers, etc., and its capacity can be selected according to actual needs.

[0029] Preferably, the mixing time in step (1) is 20 to 30 minutes, such as 21 minutes, 22 minutes, 23 minutes, 24 minutes, 25 minutes, 26 minutes, 27 minutes, 28 minutes or 29 minutes.

[0030] Preferably, the mixing temperature in step (1) is 120 to 200°C, such as 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C or 200°C.

[0031] Preferably, the extruder in step (2) includes a single-screw extruder or a twin-screw extruder.

[0032] The single-screw extruder can be selected from commercially available extruders such as Koya, Coperlon, Nanjing Ruya, or Nanjing J&T.

[0033] Preferably, the barrel temperature of the extruder in step (2) is 120 to 200°C, for example, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C or 200°C.

[0034] Preferably, the die head temperature of the extruder in step (2) is 120-200°C, such as 130°C, 140°C, 150°C, 160°C, 170°C, 180°C or 190°C.

[0035] Preferably, the screw speed of the extruder in step (2) is 15 to 20 r / min, such as 15.5 r / min, 16 r / min, 16.5 r / min, 17 r / min, 17.5 r / min, 18 r / min, 18.5 r / min, 19 r / min or 19.5 r / min.

[0036] As a preferred technical solution, the preparation method includes the following steps:

[0037] (1) The cation exchanger, binder, softener, stabilizer and antioxidant are mixed in an intensive kneading process at 120-200℃ for 20-30 min to obtain agglomerated ion exchanger;

[0038] (2) The clump-shaped ion exchanger obtained in step (1) is added to a single-screw extruder or a twin-screw extruder and extruded under the conditions of barrel temperature of 120-200℃, die temperature of 120-200℃ and screw speed of 15-20 r / min to obtain the heterogeneous tubular cation exchange membrane.

[0039] In a second aspect, the present invention provides a heterogeneous tubular cation exchange membrane, which is prepared by the preparation method described in the first aspect.

[0040] Preferably, the wall thickness of the heterogeneous tubular cation exchange membrane is 0.5 to 1 mm, for example, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm or 0.95 mm.

[0041] Preferably, the inner diameter of the heterogeneous tubular cation exchange membrane is 1 to 10 mm, such as 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm or 9 mm.

[0042] Thirdly, the present invention provides an application of the heterogeneous tubular cation exchange membrane as described in the second aspect in a membrane module.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) The method for preparing heterogeneous tubular cation exchange membrane provided by the present invention firstly mixes cation resin powder, binder, softener, stabilizer and antioxidant, and then extrudes the resulting blend to obtain the heterogeneous tubular cation exchange membrane; the preparation method is simple to operate and is formed in one step, avoiding the step of winding and bonding the obtained cation exchange membrane into a tube.

[0045] (2) The preparation method provided by the present invention can be used to prepare heterogeneous tubular cation exchange membranes with an inner diameter as low as 1 mm, while it is difficult to prepare tubular cation exchange membranes with an inner diameter of less than 10 mm in the prior art. Moreover, the heterogeneous tubular cation exchange membranes prepared by the preparation method provided by the present invention can ensure that their membrane wall thickness, capacity, water content, selective permeability and tensile strength are comparable to those of the exchange membranes provided by the prior art. Therefore, they can be used to prepare membrane modules with high packing density, which has important research significance. Attached Figure Description

[0046] Figure 1 A schematic diagram of a detection device for testing the selective permeability of the heterogeneous tubular cation exchange membrane provided by the present invention is shown, wherein 1-dialysis chamber feed tank, 2-recovery chamber feed tank, and 3-initial recovery liquid. Detailed Implementation

[0047] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0048] Example 1

[0049] A method for preparing a heterogeneous tubular cation exchange membrane, the method comprising the following steps:

[0050] (1) 250g of linear low-density polyethylene (Zhongyuan Petrochemical, 7050) was placed into a 2L internal mixer (Guangdong Lina) and internally mixed at 120℃. After complete plasticization, 50g of polyisobutylene was added for mechanical grafting. After internal mixing for 20min, 25g of calcium stearate, 5g of antioxidant 1010 and 670g of 001×7 type cation exchange resin powder were added and internal mixing was continued for 20min to obtain agglomerated ion exchange material.

[0051] (2) The clump-shaped ion exchanger obtained in step (1) is added to a single screw extruder (Nanjing JENTES SJ-30 extruder) and extruded at a temperature that is gradually increased from 120°C to 160°C in each section of the barrel, a die head temperature of 120°C and a screw speed of 15 r / min to obtain a heterogeneous tubular cation exchange membrane with a wall thickness of 0.5 mm.

[0052] Example 2

[0053] A method for preparing a heterogeneous tubular cation exchange membrane, the method comprising the following steps:

[0054] (1) Put 250g of polypropylene (Qilu Petrochemical, T30S) into a 2L internal mixer (Guangdong Lina) and mix at 200℃. After plasticization is complete, add 40g of polyisobutylene for mechanical grafting. After mixing for 20min, add 25g of calcium stearate, 5g of antioxidant 1076 and 660g of 001×7 type cation exchange resin powder and continue mixing for 20min to obtain agglomerated ion exchange material.

[0055] (2) The clump-shaped ion exchanger obtained in step (1) is added to a single screw extruder (Nanjing JENTES SJ-30 extruder) and extruded at a temperature of 15 r / min with the barrel temperature gradually increased from 120°C to 200°C, the die head temperature of 200°C, and the screw speed of 15 r / min. This yields a heterogeneous tubular cation exchange membrane with a wall thickness of 1 mm.

[0056] Example 3

[0057] A method for preparing a heterogeneous tubular cation exchange membrane, the method comprising the following steps:

[0058] (1) 250g of linear low-density polyethylene (Zhongyuan Petrochemical, 7050) was placed into a 2L internal mixer (Guangdong Lina) and internally mixed at 140℃. After complete plasticization, 50g of polyisobutylene was added for mechanical grafting. After internal mixing for 30min, 25g of calcium stearate, 5g of antioxidant 168 and 670g of 001×7 type cation exchange resin powder were added and internal mixing was continued for 20min to obtain agglomerated ion exchange material.

[0059] (2) The clump-shaped ion exchanger obtained in step (1) was added to a single screw extruder (Nanjing JENTES SJ-30 extruder) and extruded at a temperature of 120°C to 160°C in each section of the barrel, a die head temperature of 140°C and a screw speed of 20 r / min to obtain a heterogeneous tubular cation exchange membrane with a wall thickness of 0.5 mm.

[0060] Example 4

[0061] A method for preparing a heterogeneous tubular cation exchange membrane, the method comprising the following steps:

[0062] (1) Put 200g of polyvinyl chloride (Qilu Petrochemical, S-1000) into a 2L internal mixer (Guangdong Lina) and mix at 140℃. After plasticization is complete, add 50g of polyisobutylene for mechanical grafting. After mixing for 20min, add 15g of calcium stearate, 5g of antioxidant 168 and 730g of D001 type cation exchange resin powder and continue mixing for 20min to obtain agglomerated ion exchange material.

[0063] (2) The clump-shaped ion exchanger obtained in step (1) is added to a single screw extruder (Nanjing JENTES SJ-30 extruder) and extruded at a temperature that is gradually increased from 120°C to 160°C in each section of the barrel, a die head temperature of 120°C and a screw speed of 15 r / min to obtain a heterogeneous tubular cation exchange membrane with a wall thickness of 1 mm.

[0064] Example 5

[0065] A method for preparing a heterogeneous tubular cation exchange membrane, the method comprising the following steps:

[0066] (1) 125g of linear low-density polyethylene (Zhongyuan Petrochemical, 7050) and 125g of polyvinyl chloride (Qilu Petrochemical, S-1000) were put into a 2L internal mixer (Guangdong Lina) and internally mixed at 140℃. After complete plasticization, 45g of polyisobutylene was added for mechanical grafting. After internal mixing for 20min, 25g of calcium stearate, 10g of antioxidant TNP and 670g of D113 type cation exchange resin powder were added and internal mixing was continued for 20min to obtain agglomerated ion exchange material.

[0067] (2) The clump-shaped ion exchanger obtained in step (1) is added to a single screw extruder (Nanjing JENTES SJ-30 extruder) and extruded at a temperature of 120°C to 160°C in each section of the barrel, a temperature of 140°C at the die head, and a screw speed of 20 r / min to obtain a heterogeneous tubular cation exchange membrane with a wall thickness of 1 mm.

[0068] Comparative Example 1

[0069] A method for preparing a heterogeneous tubular cation exchange membrane, the method comprising the following steps:

[0070] (1) 250g of linear low-density polyethylene (Zhongyuan Petrochemical, 7050) was placed into a 2L internal mixer (Guangdong Lina) and internally mixed at 120℃. After complete plasticization, 50g of polyisobutylene was added for mechanical grafting. After internal mixing for 20min, 25g of calcium stearate, 5g of antioxidant 1010 and 670g of 001×7 type cation exchange resin powder were added and internal mixing was continued for 20min to obtain agglomerated ion exchange material.

[0071] (2) The clump of ion exchange material obtained in step (1) is added to a two-roll mill and rolled into sheets at 145°C to obtain an ion exchange membrane.

[0072] (3) The ion exchange membrane with a thickness of 0.5 mm obtained in step (2) is rolled up and bonded into a tube shape using AB glue to obtain the heterogeneous tubular anion exchange membrane.

[0073] Comparative Example 2

[0074] A method for preparing a tubular cation exchange membrane, the method comprising the following steps:

[0075] (1) Preparation of the base film: 21.3 mL of tetramethoxysilane was slowly added dropwise to 500 mL of 65 °C PVA solution (5%) over a period of 0.5 h. After all the solution was added, the mixture was stirred at 65 °C for 24 h to obtain the casting solution. 500 mL of the casting solution was coated onto a glass plate to form a rectangle. The plate was dried in a ventilated environment for three days to form a thin film, which was then bonded into a tubular membrane using 15% polyvinyl alcohol.

[0076] (2) Preparation of acidic glutaraldehyde solution: 3g glutaraldehyde, 136.32g sodium sulfate and 19.84g sulfuric acid were diluted to 1L of water to obtain acidic glutaraldehyde solution;

[0077] (3) Crosslinking treatment: The tubular membrane obtained in step (1) is gradually heated from 60°C to 130°C at a rate of 10°C per hour and maintained at 130°C for 3 hours. Then, the tubular membrane is immersed in the acidic glutaraldehyde solution obtained in step (2) and maintained at 40°C for 2.5 hours. The tubular membrane is then removed and washed with water to obtain the tubular cation exchange membrane. (For specific preparation methods, please refer to the literature "HyA,Lz B,Cw C,et al. Tubular membrane used in continuous and semi-continuous diffusion dialysis[J].Separation and Purification Technology,235(C):116147-116147.").

[0078] Performance testing:

[0079] (1) Capacity: The sulfonate content was determined by titration to express the degree of sulfonation. The heterogeneous tubular cation exchange membrane stored in 0.1 mol / L sulfuric acid was rinsed with water and then immersed in 2 mol / L NaCl solution for 8 hours. During this period, the membrane was stirred from time to time and the NaCl solution was replaced every 2 to 3 hours. The NaCl solution used for membrane immersion was collected and the H ions in the solution were titrated with NaOH and phenolphthalein indicator.

[0080] (2) Moisture content: The ion exchange membrane was immersed in a 2 mol / L NaCl solution for 6 h and the moisture content of the membrane was determined by weighing.

[0081] (3) Tensile strength: The tensile strength of the ion exchange membrane was measured using a SHIMADZU mechanical analyzer;

[0082] (4) Selective permeability: The permeability of the ion exchange membrane to Na+ was detected by diffusion dialysis. + With SO4 2-Selective permeability;

[0083] A schematic diagram of the detection device is shown below. Figure 1 As shown in the figure, 1 represents the dialysis chamber feed tank (containing the raw material solution to be treated), 2 represents the recovery chamber feed tank (containing the recovery solution), and 3 represents the initial recovery solution (usually water). A tubular ion exchange membrane is immersed in the dialysis chamber feed tank. The inner and outer sides of the ion exchange membrane tube serve as the recovery chamber and dialysis chamber, respectively. The inlet and outlet of the ion exchange membrane tube are connected to water and the recovery chamber feed tank, respectively. The feed tank positions are shown in the figure. The dialysis chamber feed tank contains a 1:1 volume ratio of 1 mol / L sodium hydroxide and 1 mol / L sodium sulfate mixed solution. The initial feed solution is water, and the initial feed solution flow rate is 2 L / m³. 2 / h. The calculation formula is: Where C is the ion concentration in the recovery chamber (mol / L) and V is the volume of the liquid in the recovery chamber (L);

[0084] (5) Inner diameter of the molded tube: Tested in accordance with GB8088-88-Methods for Measuring the Dimensions of Plastic Pipes;

[0085] (6) Crack condition: The obtained cation exchange membrane was placed in a 1 mol / L sulfuric acid system and the presence of cracks was observed.

[0086] The tubular cation exchange membranes obtained in Examples 1-5 and Comparative Examples 1-2 were tested according to the above test methods, and the test results are shown in Table 1.

[0087] Table 1

[0088]

[0089] According to the data in Table 1:

[0090] The tubular cation exchange membrane prepared by the preparation method provided by this invention has comparable basic properties (capacity, water content, selective permeability, and tensile strength) to the sheet membranes prepared by the preparation methods provided by the prior art (Comparative Example and Comparative Example 2) that are then bonded into tubular membranes. Moreover, based on the comparison of cracking conditions, it can be seen that the tubular cation exchange membranes prepared by the preparation methods provided by Comparative Example 1 and Comparative Example 2 are prone to cracking. This is because the membranes themselves are greatly affected by the bonding method and adhesive during the bonding process.

[0091] Meanwhile, according to the data in Table 1, it can also be seen that the inner diameter of the tubular cation exchange membrane prepared by the preparation method provided by the present invention is as low as 1 mm, while it is difficult to prepare tubular cation exchange membranes with an inner diameter of less than 10 mm using the preparation methods provided by Comparative Example 1 and Comparative Example 2.

[0092] The applicant declares that this invention illustrates a heterogeneous tubular cation exchange membrane, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above process steps, meaning that this invention does not necessarily rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials used in this invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.

Claims

1. A method for preparing a heterogeneous tubular cation exchange membrane, characterized by, The preparation method comprises the following steps: (1) mixing cationic resin powder, adhesive, softener, stabilizer and antioxidant to obtain a mass ion exchanger; (2) adding the mass ion exchanger obtained in step (1) into an extruder to perform extrusion at a die head temperature of 120-140 ℃ to obtain the heterogeneous tubular cation exchange membrane; The cationic resin powder in step (1) comprises any one or a combination of at least two of 001x7 resin, 001x4 resin, D001 resin or D113 resin; The tube wall thickness of the heterogeneous tubular cation exchange membrane is 0.5-1 mm; The inner diameter of the tube of the heterogeneous tubular cation exchange membrane is 1-10 mm; The adhesive in step (1) comprises any one or a combination of at least two of polyethylene, polypropylene or polyvinyl chloride; The softener in step (1) comprises polyisobutylene; The stabilizer in step (1) comprises calcium stearate; The antioxidant in step (1) comprises any one or a combination of at least two of antioxidant 1010, antioxidant 1076, antioxidant 168 or antioxidant TNP.

2. The production method according to claim 1, characterized by, The mass ion exchanger in step (1) comprises the following components in parts by weight: adhesive 20-25 parts by weight, cationic resin powder 65-75 parts by weight, softener 4-5 parts by weight, stabilizer 1-2.5 parts by weight and antioxidant 0.5-1 part by weight.

3. The preparation method according to claim 1, characterized in that, The mixing method in step (1) is internal mixing.

4. The method of claim 1, wherein, The mixing time in step (1) is 20-30 min.

5. The preparation method according to claim 1, characterized in that, The mixing temperature in step (1) is 120-200 ℃.

6. The method of claim 1, wherein, The extruder in step (2) comprises a single-screw extruder or a double-screw extruder.

7. The preparation method according to claim 1, characterized in that, The barrel temperature of the extruder in step (2) is 120-200 ℃.

8. The method of claim 1, wherein, The screw rotation speed of the extruder in step (2) is 15-20 r / min.

9. The method of claim 1, wherein, The preparation method comprises the following steps: (1) mixing cationic resin powder, adhesive, softener, stabilizer and antioxidant at 120-200 ℃ by internal mixing for 20-30 min to obtain a mass ion exchanger; (2) adding the mass ion exchanger obtained in step (1) into a single-screw extruder or a double-screw extruder to perform extrusion at a barrel temperature of 120-200 ℃, a die head temperature of 120-140 ℃ and a screw rotation speed of 15-20 r / min to obtain the heterogeneous tubular cation exchange membrane.

10. A heterogeneous tubular cation exchange membrane, characterized by, The heterogeneous tubular cation exchange membrane is prepared by the preparation method in any one of claims 1-9; The tube wall thickness of the heterogeneous tubular cation exchange membrane is 0.5-1 mm; The inner diameter of the tube of the heterogeneous tubular cation exchange membrane is 1-10 mm.

11. Use of the heterogeneous tubular cation exchange membrane in claim 10 in a membrane module.

Images