WO2015184571A1

WO2015184571A1 - Ion-conducting membrane and preparation method therefor

Info

Publication number: WO2015184571A1
Application number: PCT/CN2014/000655
Authority: WO
Inventors: 王婧; 张永明; 杨淼昆; 张恒
Original assignee: 山东东岳高分子材料有限公司
Priority date: 2014-06-06
Filing date: 2014-07-07
Publication date: 2015-12-10
Also published as: CN103993329B; CN103993329A

Abstract

The present invention belongs to the technical field of ion membranes, and specifically relates to an ion-conducting membrane and a preparation method therefor. The ion-conducting membrane consists of a perfluorinated ion exchange resin base membrane, a porous reinforcing material and a surface layer of perfluorinated sulphonic acid resin microparticles. The perfluorinated ion exchange resin base membrane consists of a resin layer which is mainly a perfluorinated sulphonic acid resin and a resin layer which is mainly a perfluorinated carboxylic acid resin. The surface layer of the present invention has good compatibility and adhesion, thus ensuring that a good degassing effect is maintained during the entire lifespan of the ion-conducting membrane. The present invention is used in the chlor-alkali industry, stably and effectively treats alkali metal chloride solutions having a wide range of concentrations, is suitable for operating in a zero pole distance electrolyser under novel high current density conditions, and has an excellent product purity index. Also provided is a preparation method for the ion-conducting membrane. The preparation method has a simple and reasonable process, and facilitates industrial production.

Description

Ion conductive membrane and preparation method thereof

Technical field

The invention belongs to the technical field of ion membranes, and in particular relates to an ion conductive membrane and a preparation method thereof.

Background technique

In recent years, in the production of ionic membrane chlor-alkali, in order to achieve electrolysis under conditions of high current density, low cell voltage, and high lye concentration, in order to achieve productivity and reduce power consumption, the key is to shorten the ion membrane. The distance between the electrodes and the electrodes is used to lower the cell voltage, and the narrow-electrode type ion-exchange membrane electrolysis process is put into practical use. With the continuous advancement of technology, the zero-pole electrolysis cell has been widely used, but when the distance between the electrodes is reduced to less than 2 mm, since the film and the cathode are in close contact, the hydrogen bubbles adhered on the film surface are difficult to release, so A large amount of hydrogen bubbles accumulate on the membrane surface facing the cathode. The air bubbles block the current channel, which reduces the effective electrolysis area of the film, resulting in uneven current distribution on the film surface, and the local polarization is significantly increased. As a result, the membrane resistance and the cell voltage are sharply increased, and the electrolysis power consumption is remarkably increased.

In order to overcome the shortcomings caused by the bubble effect, the adhered hydrogen bubbles are quickly released from the hydrophilic surface, and a modification method of the hydrophilic coating on the surface of the ion film is developed. When the surface of the membrane is covered with a porous, electrocatalytically active non-electrode coating capable of permeating both gas and liquid, the hydrophilicity of the membrane surface is significantly increased, and the anti-foaming ability is remarkably improved. The ionic membrane modified by the hydrophilic coating can be closely attached to the electrode and greatly reduce the cell voltage, and is currently widely used in the zero-pole ion membrane electrolysis process. The hydrophilic coating modification process needs to be covered by the inorganic component and the special binder, and covered on the surface of the ion membrane by electrolytic deposition method, particle embedding method, etc. The coating process is specifically introduced by patent CA2446448 and CA2444585. Although the modification method is remarkable, the process is relatively complicated. In addition, since the ionic membrane undergoes continuous scouring caused by continuous scouring and turbulence of the lye flow during the electrolysis operation, the hydrophilic coating attached to the surface of the ionic membrane gradually falls off, and the anti-foaming function is gradually reduced to ineffective.

Patent No. 4502931 mentions that the surface of the ion film is subjected to surface roughening modification by ion etching, but the method is not easy to implement in a large area, and the anti-foaming ability is not high, when the distance between the electrodes is reduced to a certain extent, The cell pressure is still greater than 3.5V and the current efficiency is less than 90%.

Therefore, a new type of ion-conducting membrane has been developed, which has a long-term effective hydrophilic degassing function, and can continuously provide good anti-foaming effect, reduce the cell voltage, and improve in the most advanced electrolyzer and electrolysis process. Current efficiency, and can reduce power consumption, is very important.

Summary of the invention

In view of the deficiencies of the prior art, the object of the present invention is to provide an ion-conducting membrane which can be stably used in the chlor-alkali industry. Effectively treating a wide range of alkali metal chloride solutions, suitable for operation in a zero-pole electrolysis cell under a novel high current density condition, and having a very excellent product purity index; the invention also provides a preparation method thereof, and the process is simple and reasonable. Easy to industrialize production.

The ion conductive membrane of the present invention comprises a perfluoro ion exchange resin base membrane, a porous reinforcing material, and a perfluorosulfonic acid resin microparticle surface layer.

Wherein: the perfluoro ion exchange resin base film is composed of a resin layer mainly composed of a perfluorosulfonic acid resin and a resin layer mainly composed of a perfluorocarboxylic acid resin, and a resin layer mainly composed of a perfluorosulfonic acid resin. The thickness of the resin is 30-300 micrometers, preferably 50-150 micrometers. The resin layer mainly composed of perfluorosulfonic acid resin has a small fixed ion content, and the repulsive force to the hydroxide is weak, and the thickness is not too thin; The resin layer mainly composed of a fluorocarboxylic acid resin has a thickness of 2 to 30 μm, preferably 7 to 18 μm, and the resin layer mainly composed of a perfluorocarboxylic acid resin has a large electric resistance and the thickness is not excessively large.

The resin layer mainly composed of perfluorosulfonic acid resin is obtained by blending or copolymerizing a perfluorosulfonic acid resin and a perfluorocarboxylic acid resin in a mass ratio of 100:0.1 to 100:10; the mass ratio thereof is preferably 100:0.5. -100:5. The presence of a small amount of perfluorocarboxylic acid resin in a resin layer mainly composed of perfluorosulfonic acid resin can play a key transition role, so that the water and ion permeability gradient in the membrane is weakened, and the flux of the ion membrane is stabilized. Sex plays a key role while preventing stripping between different layers.

The resin layer mainly composed of a perfluorocarboxylic acid resin is obtained by blending or copolymerizing a perfluorocarboxylic acid resin and a perfluorosulfonic acid resin in a mass ratio of 100:0.1 to 100:10, preferably 100:0.5-100:5. . The presence of a small amount of perfluorosulfonic acid resin in a resin layer mainly composed of a perfluorocarboxylic acid resin can also play a key transition role as described in the above paragraph.

The perfluorosulfonic acid resin has an exchange capacity of 0.8 to 1.5 mmol/g, preferably 0.9 to 1.1 mmol/g; and the perfluorocarboxylic acid resin has an exchange capacity of 0.8 to 1.2 mmol/g, preferably 0.85 to 1.0 mmol/ Gram. The exchange capacity of the two resins should be matched, and the difference should not be too large.

The surface layer thickness of the perfluorosulfonic acid resin microparticles is between 20 nm and 100 microns, preferably between 50 nm and 1 micron. The surface layer of the perfluorosulfonic acid resin microparticles is a perfluorosulfonic acid resin microparticle which is obtained by grinding the resin pellets once in a low temperature crushing apparatus and then grinding in a cryogenic apparatus. The particles have an irregular appearance and have an excellent effect on the desorption of the surface foaming. The microparticle size ranges from 20 nm to 10 microns, preferably from 50 to 300 nm. When the particle size is too low, the particles tend to agglomerate and block the ion channel; when the particle size is too high, the particles formed on the surface of the film are too prominent, and are easily detached under external force. The perfluorosulfonic acid resin microparticles have an ion exchange capacity of from 0.01 to 1.5 mmol/g, preferably from 0.3 to 1.0 mmol/g. When the ion exchange capacity is too high, there will be a certain degree of swelling in the hydroalcoholic solution, thereby destroying the irregular shape of the broken microparticles, and the volume will be enlarged, the porosity is seriously reduced, the ion channel is blocked, and the ion channel is not easily broken; Too low ion exchange capacity will affect the ion permeability of the membrane to some extent.

The porous reinforcing material is a polytetrafluoroethylene non-woven fabric, and the fiber boundary is overlapped or fused together, and the porous reinforcing material has a thickness of between 1 and 200 micrometers, preferably 10 to 50 micrometers; to improve mechanical strength, using existing The technology can be prepared. The polytetrafluoroethylene nonwoven fabric has a porosity of between 20 and 99%, preferably between 50 and 85%. If the porosity is too low, it will cause the cell pressure to rise.

The ion conductive membrane of the present invention comprises the following preparation steps:

(1) melt-casting into a perfluoro ion exchange resin base film by co-extrusion by a screw extruder, and then soaking the porous reinforcing material in a fluorocarbon solvent for ultrasonic treatment for 1-2 hours, taking out the drying and then the whole The fluorine ion exchange resin base film is composited, and a porous reinforcing material is introduced between the film forming press rolls, and the porous reinforcing material is pressed into the perfluoro ion exchange resin base film under the action of the pressure between the rolls, thereby obtaining the perfluoro ion exchange film. body.

(2) The perfluoro ion exchange membrane precursor prepared in the step (1) is converted into a perfluoro ion exchange membrane having an ion exchange function.

(3) Water and ethanol were mixed in a ratio of 1:1 by weight, and perfluorosulfonic acid resin microparticles were added and homogenized in a ball mill to form a perfluorosulfonic acid resin microparticle dispersion.

(4) The perfluorosulfonic acid resin microparticle dispersion in (3) is adhered to the surface of the perfluoro ion exchange membrane obtained in the step (2), and dried to form a finished product.

Wherein: Step (1) The porous reinforcing material is soaked in a fluorocarbon solvent for ultrasonic treatment for 1-2 hours, taken out and dried, and then combined with a perfluoro ion exchange resin base film. Since the wetting of the polytetrafluoroethylene nonwoven fabric is very difficult, if it is directly combined with the base film without treatment, the resin matrix cannot completely fill the voids of the nonwoven fabric, thereby forming a non-compact space inside the film body, not only It is easy to deposit impurities, and it can also form a space barrier and increase resistance. After the porous reinforcing material is immersed in the fluorocarbon solvent for 1-2 hours, the impregnation of the resin matrix is very easy, and the two can form a good and tight bond, which not only increases the mechanical strength, but also has a high opening ratio of the nonwoven fabric. The effect of membrane resistance is minimal.

The fluorocarbon solvent according to the step (1) is selected from the group consisting of trifluorotrichloroethane (F-113) or trifluorotrichloroethane mixed with other solvents; the other solvents are anhydrous ethanol, propanol, methanol, acetone. One or more of methylene chloride or an aqueous solution of a surfactant. The surfactant may be selected from commercially available anionic, cationic, amphoteric or nonionic surfactants.

Step (2) is to use the perfluoro ion exchange membrane precursor prepared in the step (1) at a temperature of 10 to 200 ° C under a pressure of 20 to 100 tons at a rate of 1 to 50 m / min. The press is subjected to an overpressure treatment, and after the overpressure treatment, the perfluoro ion exchange membrane precursor is immersed in a mixed aqueous solution of 15 wt% dimethyl sulfoxide and 20 wt% NaOH, and converted into a perfluoro ion exchange membrane having ion exchange function. . Among them: the overpressure treatment further increases the compactness of the nonwoven fabric and the base film, and the overpressure treatment also improves the physical structure of the nonwoven fabric and the base film to some extent, and the microfibrillation and base film of the nonwoven fabric. The thermo-induced crystal structure is refined, which will effectively improve the ion transport effect.

The perfluorosulfonic acid resin microparticles in the step (3) are obtained by first grinding the perfluorosulfonic acid resin pellets in a low-temperature crushing apparatus and then grinding them in a cryogenic apparatus. The obtained perfluorosulfonic acid resin microparticles have an irregular apparent morphology and have an excellent effect on surface defoaming desorption.

Step (4) attaching the perfluorosulfonic acid resin microparticle dispersion to the surface of the perfluoro ion exchange membrane obtained in the step (2), and the adhesion method is various, including: spraying, brushing, rolling, dipping, transferring, spinning Coating or the like is preferably spray coating or roll coating. The process operation can be carried out according to the prior art.

In summary, the present invention has the following advantages:

(1) The present invention replaces the inorganic oxide coating in the existing product with the surface layer of the perfluorosulfonic acid resin microparticles, since the perfluorosulfonic acid resin microparticles have the same chemical structure as the base film material, and have good compatibility. And adhesion, thus ensuring a good degassing effect throughout the life of the ion-conducting membrane, and the degassing effect is much better than the inorganic oxide coating.

(2) The surface layer of the perfluorosulfonic acid resin microparticles has an ion exchange function, which is beneficial to the reduction of the ion conductive membrane groove voltage and the sheet resistance.

(3) The polytetrafluoroethylene non-woven fabric is compounded with the base film after solvent treatment, and adopts an overpressure process to greatly improve the anti-impurity performance of the ion-conducting membrane while obtaining excellent electrochemical performance and mechanical properties.

(4) The present invention provides an ion-conducting membrane for electrolytically preparing sodium chloride/potassium chloride to prepare chlorine gas and sodium hydroxide/potassium hydroxide, and the introduction of the polytetrafluoroethylene nonwoven fabric improves the purity of the product. The purity of the chlorine gas obtained by electrolysis is ≥99.5%, the purity of hydrogen is ≥99.9%, and the salt in the alkali is ≤5ppm.

(5) The ion-conducting membrane of the present invention is suitable for electrolysis of a base of 30-35% concentration, whereas the ion-conducting membrane of the prior art is generally only suitable for electrolysis of a base of 30-32% concentration.

(6) The ion-conducting membrane of the present invention can be used for the chlor-alkali industry to stably and efficiently treat a wide range of alkali metal chloride solutions, and is suitable for operation in a zero-pole electrolysis cell under a novel high current density condition. At the same time of purity, the cell voltage is significantly reduced, and at a current density higher than 5.5 kA/m ² , the cell pressure is lower than 2.75V.

(7) The present invention also provides a preparation method thereof, which is simple and reasonable in process and easy to industrialize.

detailed description

The present invention will be further described below in conjunction with the embodiments.

Example 1

(1) Selecting a perfluorosulfonic acid resin with IEC=1.1 mmol/g and a perfluorocarboxylic acid resin with IEC=1.0 mmol/g to form a perfluoro ion exchange resin base film by co-extrusion casting, in the form of perfluoro The sulfonic acid resin-based resin layer has a perfluorosulfonic acid resin and a perfluorocarboxylic acid resin in a mass ratio of 100:0.5, and a perfluorocarboxylic acid resin and a perfluorosulfonic acid in a resin layer mainly composed of a perfluorosulfonic acid resin. The resin mass ratio is 100:0.5, wherein the resin layer mainly composed of perfluorosulfonic acid resin has a thickness of 110 μm, and the perfluorosulfonic acid tree is used. The lipid-based resin layer has a thickness of 10 μm. The porous reinforcing material polytetrafluoroethylene nonwoven fabric was then immersed in a trifluorotrichloroethane solvent in an ultrasonic processor for 1 hour, wherein the nonwoven fabric had a thickness of 50 μm and a porosity of 85%. The perfluoro ion exchange resin base film is compounded, a porous reinforcing material is introduced between the film forming rolls, and the porous reinforcing material is pressed into the film body under the action of the pressure between the rolls to form a perfluoro ion exchange film precursor.

(2) The perfluoro ion exchange membrane precursor prepared in the step (1) is subjected to an overpressure treatment at a temperature of 200 ° C under a pressure of 100 tons at a speed of 50 m/min. After the pressure treatment, the perfluoro ion exchange membrane precursor was immersed in a mixed aqueous solution containing 15 wt% of dimethyl sulfoxide and 20 wt% of NaOH at 85 ° C for 80 minutes to be converted into a perfluoro ion exchange membrane having an ion exchange function.

(3) Mixing water and ethanol in a weight ratio of 1:1, adding perfluorosulfonic acid resin microparticles with IEC=1.0 mmol/g, average particle size of 50 nm, and irregular polyhedral morphology (all The fluorosulfonic acid resin microparticles were obtained by first pulverizing the resin pellets in a low-temperature crushing apparatus and then grinding them in a cryogenic apparatus, and were homogenized in a ball mill to form a dispersion liquid having a content of 15% by weight.

(4) The dispersion is adhered to both sides of the perfluoro ion exchange membrane obtained in the step (2) by a spraying method, and the surface layer has a thickness of 50 nm, and is dried to form a finished product.

Performance Testing:

The prepared ion exchange membrane is subjected to an electrolysis test of an aqueous solution of sodium chloride in an electrolytic cell, and a 300 g/L aqueous solution of sodium chloride is supplied to the anode chamber, and water is supplied to the cathode chamber to ensure that the concentration of sodium chloride discharged from the anode chamber is 200g / L, the concentration of sodium hydroxide discharged from the cathode chamber is 34%; the test temperature is 90 ° C, the current density is 6.5kA / m ² , after 23 days of electrolysis experiments, the average cell pressure is 2.77V, the average current efficiency is 99.6%.

Thereafter, 15 g of inorganic Ca and Mg impurities were added to the aqueous sodium chloride solution, and an electrolysis experiment was carried out for 40 days under the same conditions as described above. The average cell pressure was stabilized at 2.78 V, and the average current efficiency was 99.6%.

The sheet resistance of the obtained film was measured to 1.0 Ω·cm ^-2 according to the standard SJ/T 10171.5 method, and the abrasion loss of the film obtained by ASTM standard D 1044-99 was 2.6 mg.

According to the standard electrolysis product testing standards, the purity of the electrolysis products was determined to be 99.5% purity of chlorine gas, 99.9% purity of hydrogen gas, and 4 ppm salt in alkali.

Comparative example 1

An ion exchange membrane having an ion exchange function was prepared in the same manner as in Example 1, and then a dispersion liquid was prepared in the same manner except that the perfluorosulfonic acid resin microparticles in the dispersion were replaced with an average particle diameter of The 50 nm inorganic oxide particles were homogenized in a ball mill to form a dispersion having a content of 15% by weight. An ion exchange membrane having an inorganic oxide coating adhered to both sides was obtained in the same manner as in Example 1.

The electrolysis test of the sodium chloride solution was carried out under the same conditions as in Example 1. After 23 days of electrolysis experiments, the average cell pressure was 2.90 V, the average current efficiency was 96.2%, and the sheet resistance was 2.3 Ω·cm ^-2 . The wear loss is 11 mg.

Comparative example 2

An ion exchange membrane having an ion exchange function was prepared in the same manner as in Example 1 except that the porous reinforcing material was not immersed in a fluorocarbon solvent before being compounded with the perfluoro ion exchange resin base film, and thereafter Overpressure treatment with an overpressure press. A perfluorosulfonic acid resin microparticle dispersion was prepared in the same manner and homogenized in a ball mill to form a dispersion having a content of 15% by weight. The ion exchange membrane product was obtained in the same manner as in Example 1.

The electrolysis test of the sodium chloride solution was carried out under the same conditions as in Example 1. After 23 days of electrolysis, the average cell pressure was 2.83 V, the average current efficiency was 99.0%, and the sheet resistance was 1.8 Ω·cm ^-2 . Thereafter, 15 g of inorganic Ca and Mg impurities were added to the aqueous sodium chloride solution, and an electrolysis experiment was carried out for 40 days under the same conditions as described above. The average cell pressure was stabilized at 2.93 V, and the average current efficiency was 97.5%. The purity of the tested products was 98.5% for chlorine, 98.7% for hydrogen, and 15 ppm for alkali.

Example 2

(1) Selecting IEC=1.05mmol/g perfluorosulfonic acid resin and IEC=0.95mmol/g perfluorocarboxylic acid resin to form a perfluoro ion exchange resin base film by co-extrusion casting, in perfluoro The sulfonic acid resin-based resin layer has a perfluorosulfonic acid resin and a perfluorocarboxylic acid resin in a mass ratio of 100:2, and a perfluorocarboxylic acid resin and a perfluorosulfonic acid in a resin layer mainly composed of a perfluorosulfonic acid resin. The resin mass ratio was 100:1.5, wherein the resin layer mainly composed of perfluorosulfonic acid resin was 130 μm, and the thickness of the resin layer mainly composed of perfluorosulfonic acid resin was 15 μm. Then, the porous reinforcing material polytetrafluoroethylene nonwoven fabric is immersed in a mixed solvent of trifluorotrichloroethane and absolute ethanol in an ultrasonic processor for 1.5 hours, wherein the nonwoven fabric has a thickness of 35 μm and a porosity of 70%. After taking out and drying, it is combined with the perfluoro ion exchange resin base film, and a porous reinforcing material is introduced between the film forming rolls, and the porous reinforcing material is pressed into the film body under the action of the pressure between the rolls to form a perfluoro ion exchange. Film precursor.

(2) The perfluoro ion exchange membrane precursor prepared in the step (1) is subjected to an overpressure treatment at a temperature of 160 ° C under a pressure of 80 tons at a speed of 35 m/min. After the pressure treatment, the perfluoro ion exchange membrane precursor was immersed in a mixed aqueous solution containing 15 wt% of dimethyl sulfoxide and 20 wt% of NaOH at 85 ° C for 80 minutes to be converted into a perfluoro ion exchange membrane having an ion exchange function.

(3) Mixing water and ethanol in a weight ratio of 1:1, adding perfluorosulfonic acid resin microparticles with IEC=0.8 mmol/g, average particle size of 60 nm, and irregular polyhedral morphology (all The fluorosulfonic acid resin microparticles were obtained by first pulverizing the resin pellets in a low-temperature crushing apparatus and then grinding them in a cryogenic apparatus, and were homogenized in a ball mill to form a dispersion liquid having a content of 15% by weight.

(4) using a roll coating method, attaching the dispersion to both sides of the perfluoro ion exchange membrane obtained in the step (2), The surface layer has a thickness of about 200 nm and is dried to form a finished product.

Performance Testing:

The prepared ion exchange membrane is subjected to an electrolysis test of an aqueous solution of sodium chloride in an electrolytic cell, and a 300 g/L aqueous solution of sodium chloride is supplied to the anode chamber, and water is supplied to the cathode chamber to ensure that the concentration of sodium chloride discharged from the anode chamber is 200g / L, the concentration of sodium hydroxide discharged from the cathode chamber is 35%; the test temperature is 90 ° C, the current density is 7.5kA / m ² , after 23 days of electrolysis experiments, the average cell pressure is 2.73V, the average current efficiency is 99.7%.

Thereafter, 15 g of inorganic Ca and Mg impurities were added to the aqueous sodium chloride solution, and an electrolysis experiment was carried out for 40 days under the same conditions as described above. The average cell pressure was stabilized at 2.73 V, and the average current efficiency was 99.7%.

The sheet resistance of the obtained film was 1.1 Ω·cm ^-2 according to the standard SJ/T 10171.5 method, and the abrasion loss of the film obtained by ASTM standard D 1044-99 was 2.8 mg.

According to the standard electrolysis product testing standards, the purity of the electrolysis products is determined to be 99.6% purity of chlorine gas, 99.9% purity of hydrogen gas, and 3 ppm salt in alkali.

Example 3

(1) Selecting a perfluorosulfonic acid resin with IEC=1.0 mmol/g and a perfluorocarboxylic acid resin with IEC=0.9 mmol/g to form a perfluoro ion exchange resin base film by co-extrusion casting, in the form of perfluoro The sulfonic acid resin-based resin layer has a perfluorosulfonic acid resin and a perfluorocarboxylic acid resin in a mass ratio of 100:3, and a perfluorocarboxylic acid resin and a perfluorosulfonic acid in a resin layer mainly composed of a perfluorosulfonic acid resin. The resin mass ratio was 100:2.5, wherein the resin layer mainly composed of a perfluorosulfonic acid resin was 150 μm, and the thickness of the resin layer mainly composed of a perfluorosulfonic acid resin was 7 μm. Then, the porous reinforcing material polytetrafluoroethylene non-woven fabric is immersed in a mixed solvent of trifluorotrichloroethane and propanol in an ultrasonic processor for 1.5 hours, wherein the non-woven fabric has a thickness of 15 μm and a porosity of 50%. After being taken out and dried, it is combined with the perfluoro ion exchange resin base film, a porous reinforcing material is introduced between the film forming rolls, and the porous reinforcing material is pressed into the film body under the action of the pressure between the rolls to form a perfluoro ion exchange film. Precursor.

(2) The perfluoro ion exchange membrane precursor prepared in the step (1) is subjected to an overpressure treatment at a temperature of 120 ° C under a pressure of 60 tons at a speed of 20 m/min. After the pressure treatment, the perfluoro ion exchange membrane precursor was immersed in a mixed aqueous solution containing 15 wt% of dimethyl sulfoxide and 20 wt% of NaOH at 85 ° C for 80 minutes to be converted into a perfluoro ion exchange membrane having an ion exchange function.

(3) Mixing water and ethanol in a weight ratio of 1:1, adding perfluorosulfonic acid resin microparticles with IEC=0.6 mmol/g, average particle size of 150 nm, and irregular polyhedral morphology (all The fluorosulfonic acid resin microparticles were obtained by first pulverizing the resin pellets in a low-temperature crushing apparatus and then grinding them in a cryogenic apparatus, and were homogenized in a ball mill to form a dispersion liquid having a content of 15% by weight.

(4) using a brushing method, attaching the dispersion to both sides of the perfluoro ion exchange membrane obtained in the step (2), The surface layer has a thickness of about 500 nm and is dried to form a finished product.

Performance Testing:

The prepared ion exchange membrane is subjected to an electrolysis test of an aqueous solution of sodium chloride in an electrolytic cell, and a 300 g/L aqueous solution of sodium chloride is supplied to the anode chamber, and water is supplied to the cathode chamber to ensure that the concentration of sodium chloride discharged from the anode chamber is 200g / L, the concentration of sodium hydroxide discharged from the cathode chamber is 32%; the test temperature is 90 ° C, the current density is 6.5kA / m ² , after 23 days of electrolysis experiments, the average cell pressure is 2.76V, the average current efficiency is 99.8%.

Thereafter, 15 g of inorganic Ca and Mg impurities were added to the aqueous sodium chloride solution, and an electrolysis experiment was carried out for 40 days under the same conditions as described above. The average cell pressure was stabilized at 2.76 V, and the average current efficiency was 99.8%.

The sheet resistance of the obtained film was measured to 1.3 Ω·cm ^-2 according to the standard SJ/T 10171.5 method, and the abrasion loss of the film obtained by ASTM standard D 1044-99 was 2.6 mg.

According to the standard electrolysis product testing standards, the purity of the electrolysis products was determined to be 99.7% purity of chlorine gas, 99.9% purity of hydrogen, and 5 ppm of salt in alkali.

Example 4

(1) Selecting a perfluorosulfonic acid resin with IEC=0.95mmol/g and a perfluorocarboxylic acid resin with IEC=0.85mmol/g to form a perfluoro ion exchange resin base film by co-extrusion casting, in the form of perfluoro The sulfonic acid resin-based resin layer has a perfluorosulfonic acid resin and a perfluorocarboxylic acid resin in a mass ratio of 100:5, and a perfluorocarboxylic acid resin and a perfluorosulfonic acid in a resin layer mainly composed of a perfluorosulfonic acid resin. The resin mass ratio was 100:4, wherein the resin layer mainly composed of a perfluorosulfonic acid resin was 75 μm, and the thickness of the resin layer mainly composed of a perfluorosulfonic acid resin was 16 μm. Then, the porous reinforcing material polytetrafluoroethylene non-woven fabric is immersed in a mixed solvent of trifluorotrichloroethane and methanol in an ultrasonic processor for 2 hours, wherein the non-woven fabric has a thickness of 50 μm and a porosity of 65%. After drying, it is compounded with the perfluoro ion exchange resin base film, and a porous reinforcing material is introduced between the film forming rolls, and the porous reinforcing material is pressed into the film body under the action of the pressure between the rolls to form a perfluoro ion exchange film. body.

(2) The perfluoro ion exchange membrane precursor prepared in the step (1) is subjected to an overpressure treatment at a temperature of 80 ° C under a pressure of 40 tons at a speed of 10 m/min. After the pressure treatment, the perfluoro ion exchange membrane precursor was immersed in a mixed aqueous solution containing 15 wt% of dimethyl sulfoxide and 20 wt% of NaOH at 85 ° C for 80 minutes to be converted into a perfluoro ion exchange membrane having an ion exchange function.

(3) Mixing water and ethanol in a weight ratio of 1:1, adding perfluorosulfonic acid resin microparticles with IEC=0.45 mmol/g, average particle diameter of 200 nm, and irregular polyhedral morphology (all The fluorosulfonic acid resin microparticles were obtained by first pulverizing the resin pellets in a low-temperature crushing apparatus and then grinding them in a cryogenic apparatus, and were homogenized in a ball mill to form a dispersion liquid having a content of 15% by weight.

(4) using a spraying method, attaching the dispersion to both sides of the perfluoro ion exchange membrane obtained in the step (2), The surface layer has a thickness of about 700 nm and is dried to form a finished product.

Performance Testing:

The prepared ion exchange membrane is subjected to an electrolysis test of an aqueous solution of sodium chloride in an electrolytic cell, and a 300 g/L aqueous solution of sodium chloride is supplied to the anode chamber, and water is supplied to the cathode chamber to ensure that the concentration of sodium chloride discharged from the anode chamber is 200g / L, the concentration of sodium hydroxide discharged from the cathode chamber is 30%; the test temperature is 90 ° C, the current density is 7.5kA / m ² , after 23 days of electrolysis experiments, the average cell pressure is 2.70V, the average current efficiency is 99.8%.

Thereafter, 15 g of inorganic Ca and Mg impurities were added to the aqueous sodium chloride solution, and an electrolysis experiment was carried out for 40 days under the same conditions as described above. The average cell pressure was stabilized at 2.71 V, and the average current efficiency was 99.8%.

The sheet resistance of the obtained film was measured to 1.2 Ω·cm ^-2 according to the standard SJ/T 10171.5 method, and the abrasion loss of the film obtained by ASTM standard D 1044-99 was 2.8 mg.

According to the standard test standards for electrolytic products, the purity of the electrolytic products is determined to be 99.7% purity of chlorine gas, 100% purity of hydrogen, and 5 ppm of salt in alkali.

Example 5

(1) Selecting a perfluorosulfonic acid resin with IEC=0.9 mmol/g and a perfluorocarboxylic acid resin with IEC=0.85 mmol/g to form a perfluoro ion exchange resin base film by co-extrusion casting, in the form of perfluoro The sulfonic acid resin-based resin layer has a perfluorosulfonic acid resin and a perfluorocarboxylic acid resin in a mass ratio of 100:3, and a perfluorocarboxylic acid resin and a perfluorosulfonic acid in a resin layer mainly composed of a perfluorosulfonic acid resin. The resin mass ratio was 100:5, wherein the resin layer mainly composed of a perfluorosulfonic acid resin was 50 μm, and the thickness of the resin layer mainly composed of a perfluorosulfonic acid resin was 18 μm. Then, the porous reinforcing material polytetrafluoroethylene non-woven fabric is immersed in a mixed solvent of trifluorotrichloroethane and acetone in an ultrasonic processor for 2 hours, wherein the non-woven fabric has a thickness of 10 μm and a porosity of 85%. After drying, it is compounded with the perfluoro ion exchange resin base film, and a porous reinforcing material is introduced between the film forming rolls, and the porous reinforcing material is pressed into the film body under the action of the pressure between the rolls to form a perfluoro ion exchange film. body.

(2) The perfluoro ion exchange membrane precursor prepared in the step (1) is subjected to an overpressure treatment at a temperature of 10 ° C under a pressure of 20 tons at a speed of 1 m/min using an overpressure press. After the pressure treatment, the perfluoro ion exchange membrane precursor was immersed in a mixed aqueous solution containing 15 wt% of dimethyl sulfoxide and 20 wt% of NaOH at 85 ° C for 80 minutes to be converted into a perfluoro ion exchange membrane having an ion exchange function.

(3) Mixing water and ethanol in a weight ratio of 1:1, adding perfluorosulfonic acid resin microparticles with IEC=0.3 mmol/g, average particle size of 300 nm, and irregular polyhedral morphology (all The fluorosulfonic acid resin microparticles were obtained by first pulverizing the resin pellets in a low-temperature crushing apparatus and then grinding them in a cryogenic apparatus, and were homogenized in a ball mill to form a dispersion liquid having a content of 15% by weight.

(4) using a spraying method, attaching the dispersion to both sides of the perfluoro ion exchange membrane obtained in the step (2), The top layer has a thickness of about 1 micron and is dried to form a finished product.

Performance Testing:

The prepared ion exchange membrane is subjected to an electrolysis test of an aqueous solution of sodium chloride in an electrolytic cell, and a 300 g/L aqueous solution of sodium chloride is supplied to the anode chamber, and water is supplied to the cathode chamber to ensure that the concentration of sodium chloride discharged from the anode chamber is 200g / L, the concentration of sodium hydroxide discharged from the cathode chamber is 34%; the test temperature is 90 ° C, the current density is 5.5kA / m ² , after 23 days of electrolysis experiments, the average cell pressure is 2.71V, the average current efficiency is 99.7%.

Thereafter, 15 g of inorganic Ca and Mg impurities were added to the aqueous sodium chloride solution, and an electrolysis experiment was carried out for 40 days under the same conditions as described above. The average cell pressure was stabilized at 2.70 V, and the average current efficiency was 99.7%.

The sheet resistance of the obtained film was measured to 1.0 Ω·cm ^-2 according to the standard SJ/T 10171.5 method, and the abrasion loss of the film obtained by ASTM standard D 1044-99 was 2.7 mg.

According to the standard electrolysis product testing standards, the purity of the electrolyzed products was determined to be 99.8% purity of chlorine gas, 99.9% purity of hydrogen gas, and 2 ppm salt in alkali.

Claims

An ion-conducting membrane characterized by comprising a perfluoro ion exchange resin base film, a porous reinforcing material, and a perfluorosulfonic acid resin microparticle surface layer.
The ion-conducting membrane according to claim 1, wherein the perfluoro ion exchange resin base film is a resin layer mainly composed of a perfluorosulfonic acid resin and a resin layer mainly composed of a perfluorocarboxylic acid resin. The resin layer mainly composed of a perfluorosulfonic acid resin has a thickness of 30 to 300 μm, and the resin layer mainly composed of a perfluorocarboxylic acid resin has a thickness of 2 to 30 μm.
The ion-conducting membrane according to claim 2, wherein the perfluorosulfonic acid resin-based resin layer is a perfluorosulfonic acid resin and a perfluorocarboxylic acid resin in a mass ratio of 100:0.1 to 100:10. The resin layer mainly composed of a perfluorocarboxylic acid resin is blended or copolymerized with a perfluorocarboxylic acid resin and a perfluorosulfonic acid resin in a mass ratio of 100:0.1 to 100:10.
The ion-conducting membrane according to claim 3, wherein the perfluorosulfonic acid resin has an exchange capacity of 0.8 to 1.5 mmol/g, and the perfluorocarboxylic acid resin has an exchange capacity of 0.8 to 1.2 mmol/g.
The ion-conducting membrane according to claim 1, wherein the surface layer of the perfluorosulfonic acid resin microparticles is between 20 nm and 100 micrometers, and the surface layer of the perfluorosulfonic acid resin microparticles is a perfluorosulfonic acid resin microparticle. The particles, the microparticles have a particle size ranging from 20 nm to 10 microns, and the perfluorosulfonic acid resin microparticles have an ion exchange capacity of from 0.01 to 1.5 mmol/g.
The ion-conducting membrane according to claim 1, wherein the porous reinforcing material is a polytetrafluoroethylene nonwoven fabric, and the fiber boundary is overlapped or fused, and the porous reinforcing material has a thickness of between 1 and 200 μm. .
The ion-conducting membrane according to claim 6, wherein the polytetrafluoroethylene nonwoven fabric has a porosity of between 20 and 99%.
A method of preparing an ion-conducting membrane according to any one of claims 1 to 7, comprising the steps of:

(1) melt-casting into a perfluoro ion exchange resin base film by co-extrusion by a screw extruder, immersing the porous reinforcing material in a fluorocarbon solvent, and sonicating for 1-2 hours, taking out and drying It is compounded with a perfluoro ion exchange resin base film, a porous reinforcing material is introduced between the film forming rolls, and the porous reinforcing material is pressed into the perfluoro ion exchange resin base film by the pressure between the rolls to obtain a perfluoro ion exchange. Membrane precursor

(2) converting the perfluoro ion exchange membrane precursor prepared in the step (1) into a perfluoro ion exchange membrane having an ion exchange function;

(3) mixing water and ethanol in a weight ratio of 1:1, adding perfluorosulfonic acid resin microparticles, and homogenizing in a ball mill to form a perfluorosulfonic acid resin microparticle dispersion;

(4) The perfluorosulfonic acid resin microparticle dispersion in (3) is adhered to the surface of the perfluoro ion exchange membrane obtained in the step (2), and dried to form a finished product.
The method of preparing an ion-conducting membrane according to claim 8, wherein the step (2) is the step (1) The perfluorinated ion exchange membrane precursor prepared in the medium is subjected to an overpressure treatment at a temperature of 10 to 200 ° C at a pressure of 20 to 100 tons at a speed of 1 to 50 m/min, and an overpressure treatment. Thereafter, the perfluoro ion exchange membrane precursor was immersed in a mixed aqueous solution of 15 wt% dimethyl sulfoxide and 20 wt% NaOH to be converted into a perfluoro ion exchange membrane having an ion exchange function.
The method for preparing an ion-conducting membrane according to claim 8, wherein the perfluorosulfonic acid resin microparticles in the step (3) are pulverized by the perfluorosulfonic acid resin pellets in a low-temperature crushing device, and then Grinding in a cryogenic device.