WO2015184572A1

WO2015184572A1 - Novel ion-conducting membrane used in chlor-alkali industry and preparation method therefor

Info

Publication number: WO2015184572A1
Application number: PCT/CN2014/000656
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: CN104018181A; CN104018181B

Abstract

The present invention belongs to the technical field of ion membranes, and specifically relates to a novel ion-conducting membrane used in the chlor-alkali industry, consisting of a perfluorinated ion exchange resin base membrane, a porous reinforcing material and a surface layer made by mixing fluorine-containing resin microparticles and inorganic compound particles. The inorganic compound particles are selected from one or more of oxides, hydroxides and nitrides of group IV-A elements, group IV-B elements, group V-B elements, iron, cobalt, nickel, chromium, manganese and boron. The fluorine-containing resin microparticles are selected from one or more of polytetrafluoroethylene microparticles, PFA microparticles, fluorinated ethylene propylene microparticles, poly(perfluoropropyl vinyl ether) microparticles and polyvinylidene fluoride microparticles. The present invention is used in the chlor-alkali industry, and stably and effectively treats alkali metal chloride solutions having a wide range of concentrations. The present invention is suitable for operating in a zero pole distance electrolyser under novel high current density conditions, and product purity is high. Also provided is a preparation method for the novel ion-conducting membrane. The preparation method has a simple and reasonable process, and facilitates industrial production.

Description

Novel ion conductive membrane for chlor-alkali industry and preparation method thereof

Technical field

The invention belongs to the technical field of ion membranes, and in particular relates to a novel ion conductive membrane for a chlor-alkali industry 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 for the chlor-alkali industry has been developed, which has a long-term effective hydrophilic degassing function and can continuously provide good anti-foaming effect in the most advanced electrolyzers and electrolysis processes. It is very important to reduce the tank voltage, improve the current efficiency, and reduce the power consumption.

Summary of the invention

In view of the deficiencies of the prior art, the object of the present invention is to provide a novel ion-conducting membrane for the chlor-alkali industry, which can stably and efficiently process a wide range of alkali metal chloride solutions in a chlor-alkali industry, and is suitable for a novel high current density. Under the condition of running in the zero-pole electrolysis cell, it has very excellent product purity index; the invention also provides a preparation method thereof, the process is simple and reasonable, and the industrial production is easy.

The novel ion-conducting membrane for chlor-alkali industry according to the present invention is composed of a perfluoro ion exchange resin base film, a porous reinforcing material, and a surface layer in which fine particles of fluorine-containing resin and inorganic compound particles are mixed.

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 fluorine-containing resin microparticles mixed with the inorganic compound particles is between 20 nm and 100 μm, preferably between 200 nm and 2 μm. The mass ratio of the fluorine-containing resin microparticles to the inorganic compound particles in the surface layer is from 1:100 to 100:1. The surface layer is formed by mixing fluororesin microparticles with inorganic compound particles. Experiments have shown that the two particles are mixed and applied to the surface layer at an appropriate ratio, giving the ion conductive membrane excellent electrochemical performance while It is suitable for the acid addition process of the electrolysis process, and is resistant to the excessive acid addition by mistake, which improves the antiprotonation ability of the entire conductive film under strong acidic conditions. Wherein: the fluororesin microparticles are selected from the group consisting of polytetrafluoroethylene microparticles (PTFE), PFA microparticles, polyperfluoroethylene propylene microparticles (FEP), polyperfluoropropyl vinyl ether microparticles or polyvinylidene fluoride microparticles. One or any mixture of particles (PVDF). The fluorine-containing resin microparticles are obtained by grinding the resin pellets once in a low-temperature crushing device and then grinding them in a cryogenic apparatus. The particles have an irregular appearance and are excellent for surface foaming desorption. Effect. Surface layer The fluororesin microparticles have a particle size ranging 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 inorganic compound particles are selected from the group consisting of oxides, hydroxides, nitrides, or a mixture of any of a group IV-A, IV-B, VB, iron, cobalt, nickel, chromium, manganese or boron. Preferably, one or more of zirconium oxide, cerium oxide, tin oxide, iron oxide, titanium oxide, silicon oxide, zirconium hydroxide or zirconium nitride. The inorganic compound particles in the surface layer have a particle size ranging from 20 nm to 10 microns, preferably from 20 to 300 nm.

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 novel ion-conducting membrane for chlor-alkali industry according to 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 immersing the porous reinforcing material in a fluorocarbon solvent, sonicating for 1-2 hours, taking out and drying, and then The perfluoro ion exchange resin base film is composited, 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 under the pressure between the rolls to obtain a perfluoro ion exchange membrane. Precursor.

(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 are mixed in a ratio of 1:1 by weight, and a mixture of fluorine-containing resin microparticles and inorganic compound particles is added and homogenized in a ball mill to form a dispersion.

(4) The 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 fluorine-containing resin microparticles in the step (3) are obtained by grinding the resin pellets once in a low-temperature crushing apparatus and then grinding them in a cryogenic apparatus. The obtained fluorine-containing resin microparticles have an irregular appearance and have an excellent effect on the defoaming of the surface layer.

Step (4) attaching the dispersion in (3) to the surface of the perfluoro ion exchange membrane obtained in the step (2), and the adhesion method is various, including: spraying, brushing, roll coating, dipping, transfer, spin coating, etc. The method 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 a surface layer obtained by mixing fine particles of fluorine-containing resin and inorganic compound particles, and has good chemical structure similar to that of the base film material. 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 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.

(3) The present invention provides an ion-conducting membrane for electrolyzing sodium chloride/potassium chloride for preparing 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 invention imparts excellent electrochemical performance to the ion-conducting membrane, is more suitable for the acid-adding process of the electrolysis process, and is resistant to excessive acid addition by mistake, and improves the entire conductive membrane under strong acidic conditions. The ability to resist protonation.

(8) 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 IEC=1.05mmol/g perfluorosulfonic acid resin and IEC=1.0mmol/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 100:0.5, and a perfluorocarboxylic acid resin and a perfluorosulfonic acid in a resin layer mainly composed of a perfluorosulfonic acid resin. The resin mass ratio was 100:1, wherein the resin layer mainly composed of perfluorosulfonic acid resin was 120 μm, and the thickness of the resin layer mainly composed of perfluorosulfonic acid resin was 10 μm. The porous reinforcing material polytetrafluoroethylene nonwoven fabric was then immersed in a trifluorotrichloroethane solvent in an ultrasonic processor for 1.5 hours, 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) Water and ethanol are mixed in a weight ratio of 1:1, and fluorine-containing resin microparticles having an average particle diameter of 300 nm and having an irregular polyhedral morphology and inorganic compound particles having an average particle diameter of 20 nm are added. a homogeneous mixture (the fluororesin microparticles are obtained by grinding the resin pellets once in a low-temperature crushing device and then grinding them in a cryogenic apparatus), and homogenizing them in a ball mill to form a dispersion having a content of 15% by weight. Wherein: the mixed mass ratio of the fluorine-containing resin fine particles PFA to the inorganic compound particles zirconia is 1:100.

(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 1 μm, 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 2.76V, 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 2.77 V, and the average current efficiency was 99.7%.

Adding an excess of 17% hydrochloric acid to the anode of the electrolytic cell, causing the pH of the pale salt water to reach 1.5, and then quickly recovering to normal operating parameters by emergency operation, and then performing electrolysis. The stable cell pressure is 2.79V, and the current efficiency is 99.5. %, the membrane is sustainable and the performance is good.

The sheet resistance of the obtained film was 1.1 Ω·cm ^-2 according to the standard SJ/T10171.5 method, and the abrasion loss of the film obtained by ASTM standard D1044-99 was 2.7 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, and 3 ppm of 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 mixed particles of the fluorine-containing resin and the inorganic compound in the dispersion were replaced with an average particle. 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.

Adding an excess of 17% hydrochloric acid to the anode of the electrolytic cell, causing the pH of the pale salt water to reach 1.5, and then quickly recovering to normal operating parameters by emergency operation, and then performing electrolysis. The stable cell pressure is 6.87V, and the current efficiency is 70.5. %, the film is completely scrapped.

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 fine particle dispersion liquid of a fluorine-containing resin and an inorganic compound was prepared in the same manner and homogenized in a ball mill to form a dispersion liquid 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 100:0.5, wherein the resin layer mainly composed of a perfluorosulfonic acid resin was 80 μm, and the thickness of the resin layer mainly composed of a perfluorosulfonic acid resin was 15 μm. The porous reinforcing material polytetrafluoroethylene non-woven fabric is then immersed in a mixed solvent of trifluorotrichloroethane and absolute ethanol in an ultrasonic processor for 2 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 120 ° C under a pressure of 60 tons at a speed of 15 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) Water and ethanol are mixed in a weight ratio of 1:1, and fluorine-containing resin microparticles having an average particle diameter of 200 nm and having an irregular polyhedral morphology and inorganic compound particles having an average particle diameter of 50 nm are added. The homogeneous mixture (the fluororesin microparticles and the inorganic compound particles are all obtained by grinding the resin pellets once after being pulverized in a low-temperature crushing device and then grinding in a cryogenic apparatus), and are homogenized in a ball mill to form a content of 15 wt% dispersion. The mixing ratio of the fluorine-containing resin fine particles FEP to the inorganic compound particles silica is 1:1.

(4) The dispersion is adhered to both sides of the perfluoro ion exchange membrane obtained in the step (2) by a roll coating method, and the surface layer has a thickness of about 900 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 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 2.74 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/T10171.5 method, and the abrasion loss of the film obtained by ASTM standard D1044-99 was 2.7 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, 99.8% purity of hydrogen, and 3 ppm of salt in alkali.

Example 3

(1) Selecting IEC=1.1mmol/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 100:3, 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 2 hours, wherein the non-woven fabric has a thickness of 10 μm and a porosity of 60%. 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 80 ° C under a pressure of 60 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) Water and ethanol are mixed in a weight ratio of 1:1, and fluorine-containing resin microparticles having an average particle diameter of 150 nm and having irregular polyhedral morphology and inorganic compound particles having an average particle diameter of 500 nm are added. a homogeneous mixture (the fluororesin microparticles are obtained by grinding the resin pellets once in a low-temperature crushing device and then grinding them in a cryogenic apparatus), and homogenizing them in a ball mill to form a dispersion having a content of 15% by weight. . The mixed mass ratio of the fluorine-containing resin microparticles PVDF to the inorganic compound particulate titanium oxide is 1:50.

(4) Using a brushing method, the dispersion is adhered to both sides of the perfluoro ion exchange membrane obtained in the step (2), and the surface layer has a thickness of about 2 μm, 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 6.5kA / m ² , after 23 days of electrolysis experiments, the average cell pressure is 2.75V, 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 2.75 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/T10171.5 method, and the abrasion loss of the film obtained by ASTM standard D1044-99 was 2.6 mg.

According to the standard electrolysis product testing standards, the purity of the electrolysis products was determined to be 99.8% 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 100:5, wherein the resin layer mainly composed of perfluorosulfonic acid resin was 75 μm, and the thickness of the resin layer mainly composed of perfluorosulfonic acid resin was 15 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 1 hour, wherein the nonwoven fabric has a thickness of 15 μm and a porosity of 75%. 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 30 ° C under a pressure of 40 tons at a speed of 10 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 fluorine-containing resin microparticles having an average particle diameter of 50 nm, having an irregular polyhedral morphology, and inorganic compound particles having an average particle diameter of 300 nm a homogeneous mixture (the fluororesin microparticles are obtained by grinding the resin pellets once in a low-temperature crushing device and then grinding them in a cryogenic apparatus), and homogenizing them in a ball mill to form a dispersion having a content of 15% by weight. . Wherein: the mixed mass ratio of the fluorine-containing resin microparticle PTFE to the inorganic compound particles zirconium hydroxide is 100:1.

(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 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 31%; 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 2.71V, 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 2.71 V, and the average current efficiency was 99.7%.

The sheet resistance of the obtained film was measured to 1.2 Ω·cm ^-2 according to the standard SJ/T10171.5 method, and the abrasion loss of the film obtained by ASTM standard D1044-99 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, 100% purity of hydrogen, and 3 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 100:5.5, 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 100:5, 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 1.5 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 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) Water and ethanol are mixed in a weight ratio of 1:1, and fluorine-containing resin microparticles having an average particle diameter of 200 nm and having an irregular polyhedral morphology and inorganic compound particles having an average particle diameter of 50 nm are added. The homogeneous mixture (the fluorine-containing resin microparticles were obtained by one-time pulverization in a low-temperature crushing apparatus and then ground in a cryogenic apparatus) was homogenized in a ball mill to form a dispersion liquid having a content of 15% by weight. The mixed mass ratio of the fluorine-containing resin fine particles PFA to the inorganic compound particles tin oxide is 50:1.

(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 about 1 μm, 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 5.5kA / m ² , after 23 days of electrolysis experiments, the average cell pressure is 2.70V, the average current efficiency is 99.7%.

According to the standard electrolysis product testing standards, the purity of the electrolysis products is determined to be 99.8% purity of chlorine gas, 99.9% purity of hydrogen gas, and 3 ppm salt in alkali.

Claims

A novel ion-conducting membrane for use in a chlor-alkali industry, characterized by comprising a perfluoro ion exchange resin base film, a porous reinforcing material, and a surface layer of a mixture of fluororesin microparticles and inorganic compound particles.
A novel ion-conducting membrane for use in the chlor-alkali industry according to claim 1, wherein said perfluoro ion exchange resin base film is a resin layer mainly composed of perfluorosulfonic acid resin and perfluorocarboxylic acid. Resin-based resin layer composition, the thickness of the resin layer mainly composed of perfluorosulfonic acid resin is 30-300 μm, the thickness of the resin layer mainly composed of perfluorocarboxylic acid resin is 2-30 μm; and the perfluorosulfonic acid resin The main resin layer is blended or copolymerized with 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 mass The perfluorocarboxylic acid resin and the perfluorosulfonic acid resin having a ratio of 100:0.1 to 100:10 are blended or copolymerized.
A novel ion-conducting membrane for use in the chlor-alkali industry according to claim 2, 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 novel ion-conducting membrane for chlor-alkali industry according to claim 1, wherein the surface layer of the fluorine-containing resin microparticles mixed with the inorganic compound particles has a thickness of between 20 nm and 100 μm, and is contained in the surface layer. The mass ratio of the fluororesin microparticles to the inorganic compound particles is from 1:100 to 100:1.
A novel ion-conducting membrane for use in the chlor-alkali industry according to claim 1, wherein the inorganic compound particles are selected from the group consisting of Group IV-A, Group IV-B, Group VB, iron, cobalt, nickel, chromium, manganese or boron. One or a mixture of any of the oxides, hydroxides, and nitrides of the element.
The novel ion-conducting membrane for chlor-alkali industry according to claim 1, wherein the fluorine-containing resin microparticles are selected from the group consisting of polytetrafluoroethylene microparticles, PFA microparticles, polyperfluoroethylenepropylene microparticles, and polyperfluorocarbon. One or a mixture of any of propyl vinyl ether microparticles or polyvinylidene fluoride microparticles.
A novel ion-conducting membrane for use in the chlor-alkali industry according to claim 1, 5 or 6, characterized in that the fluorine-containing resin microparticles in the surface layer have a particle size ranging from 20 nm to 10 μm; The inorganic compound particles have a particle size ranging from 20 nm to 10 microns.
The novel ion-conducting membrane for chlor-alkali industry according to claim 1, wherein the porous reinforcing material is a polytetrafluoroethylene nonwoven fabric, and the fiber boundary is overlapped or fused, and the thickness of the porous reinforcing material is between Between 1-200 microns; polytetrafluoroethylene non-woven fabric porosity between 20-99%.
A method for preparing a novel ion-conducting membrane for use in a chlor-alkali industry according to claim 1, comprising the steps of:

(1) melt-casting into a perfluoro ion exchange resin base film by co-extrusion by a screw extruder, and then immersing the porous reinforcing material in a fluorocarbon solvent, sonicating for 1-2 hours, taking out and drying, and then Perfluoro ion exchange resin base film Compounding, introducing a porous reinforcing material between the film forming press rolls, pressing the porous reinforcing material into the perfluoro ion exchange resin base film under the action of the pressure between the rolls, thereby obtaining a perfluoro ion exchange film 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 a mixture of fluororesin microparticles and inorganic compound particles, and homogenizing in a ball mill to form a dispersion;

(4) The 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 for preparing a novel ion-conducting membrane for use in a chlor-alkali industry according to claim 9, wherein the fluororesin microparticles in the step (3) are pulverized by the resin pellets in a low-temperature crushing device, and then Grinding in a cryogenic device.