Ion-conducting membrane used in chlor-alkali industry and preparation method thereof

Abstract

An ion-conducting membrane used in the chlor-alkali industry and a preparation method thereof are disclosed. The ion-conducting membrane includes a perfluorinated ion exchange resin base film, a porous reinforcing material and a perfluorinated ion exchange resin micro-particle surface layer. The perfluorinated ion exchange resin micro-particles are a mixture of one or two of perfluorocarboxylic acid resin micro-particles and perfluorosulfonic acid carboxylic acid copolymer resin micro-particles with perfluorosulfonic acid resin micro-particles. A mass percentage of perfluorosulfonic acid resin micro-particles in the mixture is 50-95%. The surface layer of the present invention has good compatibility and adhesion, and maintains a good degassing effect during the entire lifespan of the ion-conducting membrane. The present invention is used in the chlor-alkali industry, stably and effectively processes alkali metal chloride solutions having a wide range concentration and suitable for operating in a zero polar distance electrolytic cell under novel high current density conditions.

Claims

1. An ion-conducting membrane for chlor-alkali industry, comprising: a perfluorinated ion exchange resin base film, a porous reinforcing material and a perfluorinated ion exchange resin micro-particle surface layer.

2. The ion-conducting membrane for chlor-alkali industry, as recited in claim 1, wherein: the perfluorinated ion exchange resin base film comprises a resin layer mainly made of perfluorosulfonic acid resin with a thickness of 30-300 m and a resin layer mainly made of perfluorocarboxylic acid resin with a thickness of 2-30 m.

3. The ion-conducting membrane for chlor-alkali industry, as recited in claim 2, wherein: the resin layer mainly made of perfluorosulfonic acid resin is formed by blending or copolymerizing the perfluorosulfonic acid resin and the perfluorocarboxylic acid resin with a mass ratio in a range of 100:0.1-100:10.

4. The ion-conducting membrane for chlor-alkali industry, as recited in claim 3, wherein: an exchange capacity of the perfluorosulfonic acid resin is 0.8-1.5 mmol/g, and an exchange capacity of the perfluorocarboxylic acid resin is 0.8-1.2 mmol/g.

5. The ion-conducting membrane for chlor-alkali industry, as recited in claim 1, wherein: a thickness of the perfluorinated ion exchange resin micro-particle surface layer is 20 nm-100 m, the perfluorinated ion exchange resin micro-particle surface layer are perfluorosulfonic acid resin micro-particles with a particle size of 20 nm-10 m, and an ion exchange capacity of the perfluorinated ion exchange resin micro-particles is in a range of 0.01-1.5 mmol/g.

6. The ion-conducting membrane for chlor-alkali industry, as recited in claim 1, wherein: the perfluorinated ion exchange resin micro-particles are a mixture of one or two of perfluorocarboxylic acid resin micro-particles and perfluorosulfonic acid carboxylic acid copolymer resin micro-particles with perfluorosulfonic acid resin micro-particles; wherein: a weight percentage of the perfluorosulfonic acid resin micro-particles in the mixture is 50-95%

7. The ion-conducting membrane for chlor-alkali industry, as recited in claim 1, wherein: the porous reinforcing material is polytetrafluoroethylene non-woven fabric whose fiber junctions are lapped or fused together, a thickness of the porous reinforcing material is in a range of 1-200 m, and a porosity of the polytetrafluoroethylene non-woven fabric is in a range of 20-99%.

8. A preparation method of an ion-conducting membrane used in chlor-alkali industry comprising steps of: (1) through a screw extruder, in a co-extrusion manner, melting and casting, forming a perfluorinated ion exchange resin base film, immersing a porous reinforcing material into a fluorocarbon solvent, ultrasonically processing the porous reinforcing material for 1-2 hours, taking out and drying the ultrasonically-processed porous reinforcing material, compounding the dried porous reinforcing material with the perfluorinated ion exchange resin base film, introducing the porous reinforcing material between two membrane forming rollers, pressing the porous reinforcing material into the perfluorinated ion exchange resin base film under an action of a pressure between the rollers, and forming a perfluorinated ion exchange membrane precursor; (2) converting the perfluorinated ion exchange membrane precursor obtained in the step (1) into an perfluorinated ion exchange membrane with ion exchange function; (3) preparing a mixed solution by mixing water and ethanol with a weight ratio of 1:1, adding perfluorinated ion exchange resin micro-particles into the mixed solution, and then homogenizing in a ball mill, and forming a perfluorinated ion exchange resin micro-particle dispersion liquid; and (4) attaching the perfluorinated ion exchange resin micro-particle dispersion liquid obtained in the step (3) to a surface of the perfluorinated ion exchange membrane obtained in the step (2), and forming a product after drying.

9. The preparation method of the ion-conducting membrane used in chlor-alkali industry, as recited in claim 8, wherein: the step (2) comprises: ultrasonically processing the perfluorinated ion exchange membrane precursor through an overpressure machine at 10-200 C. under a pressure of 20-100 tons with a speed of 1-50 m/min, and then immersing the perfluorinated ion exchange membrane precursor into a mixed aqueous solution comprising 15 wt % dimethyl sulfoxide and 20 wt % NaOH by weight, and forming the perfluorinated ion exchange membrane with ion exchange function.

10. The preparation method of the ion-conducting membrane used in chlor-alkali industry, as recited in claim 8, wherein: in the step (3), the perfluorinated ion exchange resin micro-particles are obtained by crushing the resin pellets for once in the low-temperature crushing device and then grinding in the cryogenic system.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0038] The present invention is further explained with accompanying embodiments in detail.

EXAMPLE 1

[0039] (1) Select perfluorosulfonic acid resin with IEC=1.05 mmol/g and perfluorocarboxylic acid resin with IEC=1.0 mmol/g; form a perfluorinated ion exchange resin base film in a co-extrusion and cast manner, wherein: in a resin layer mainly made of perfluorosulfonic acid resin, a weight ratio of the perfluorosulfonic acid resin to perfluorocarboxylic acid resin is 100:1; in a resin layer mainly made of the perfluorocarboxylic acid resin, a weight ratio of the perfluorocarboxylic acid resin to the perfluorosulfonic acid resin is 100:1; the resin layer mainly made of perfluorosulfonic acid resin has a thickness of 120 m, and resin layer mainly made of the perfluorocarboxylic acid resin has a thickness of 10 m; and then immerse a porous reinforcing material polytetrafluoroethylene non-woven fabric in trifluoro-trichloroethane solvent in an ultrasound processor for 1.5 hours, wherein: a thickness of the non-woven fabric is 40 m, a porosity is 75%; take out and dry the non-woven fabric; and then compound with the perfluorinated ion exchange resin base film; introduce a porous reinforcing material between two membrane forming rollers, press the porous reinforcing material into a membrane body under a pressure between the rollers, and form a perfluorinated ion exchange membrane precursor.

[0040] (2) Ultrasonically process the perfluorinated ion exchange membrane precursor obtained in the step (1) through an overpressure machine at 180 C. under a pressure of 80 tons with a speed of 40 m/min, and then immerse the perfluorinated ion exchange membrane precursor into a mixed aqueous solution comprising 15 wt % dimethyl sulfoxide and 20 wt % NaOH by weight at 85 C. for 80 minutes, and form a perfluorinated ion exchange membrane with ion exchange function.

[0041] (3) Prepare a mixed solution by mixing water and ethanol with a weight ratio of 1:1; add perfluorinated ion exchange resin micro-particles (which are obtained by crushing resin pellets for once in a low-temperature crushing device and then grinding in a cryogenic system) with IEC=0.85 mmol/g, an average particle size of 60 nm, and irregular polygon topography, into the mixed solution; and then homogenize in a ball mill, and form a dispersion liquid with a content of 15 wt %, wherein: the perfluorinated ion exchange resin micro-particles are a mixture of the perfluorosulfonic acid resin micro-particles and the perfluorocarboxylic acid resin micro-particles; a weight percentage of the perfluorosulfonic acid resin micro-particles in the mixture is 50%.

[0042] (4) Attach the dispersion liquid to a surface of two sides of the perfluorinated ion exchange membrane obtained in the step (2), wherein: a thickness of the surface layer is 200 nm; and form a product after drying.

[0043] Performance Testing:

[0044] An electrolytic test of the prepared ion exchange membrane about NaCl aqueous solution in an electrolysis cell is performed. 300 g/L NaCl aqueous solution is supplied to an anode chamber, water is supplied to a cathode chamber, it is ensured that a concentration of NaCl discharged from the anode chamber is 200 g/L, and a concentration of NaOH discharged from the cathode chamber is 34%; a test temperature is 90 C., a current density is 7.5 kA/m.sup.2; after 23 days of electrolysis experiments, the average cell voltage is 2.74 V and the average current efficiency is 99.4%.

[0045] Afterwards, 15 ppb inorganic matter Ca and Mg impurity are added to the NaCl aqueous solution; under the same conditions, after 40 days of electrolysis experiments, the average cell voltage is 2.75 V and the average current efficiency is 99.4%.

[0046] Based on standard SJ/T 10171.5, a surface resistance of the obtained membrane is tested to be 1.1 .Math.cm.sup.2; based on ASTM Standard D 1044-99, a wear loss of the obtained membrane is tested to be 2.7 mg.

[0047] According to electrolytic product testing standards, a purity of the electrolytic product is as follows. A purity of chlorine gas is 99.4%, that of hydrogen gas is 99.8% and a content of salt in alkali is 4 ppm.

Comparative Example 1

[0048] A same method as the example 1 is adopted to prepare the ion exchange membrane with ion exchange function; afterwards, a same method is adopted to prepare the dispersion liquid. Differences between the example 1 and the comparative example 1 are as follows. The perfluorinated ion exchange resin micro-particles in the dispersion liquid are replaced by inorganic oxide particles with an average particle size of 60 nm, and then homogenized in the ball mill, and the dispersion liquid with a content of 15 wt % is formed. The same method is adopted to obtain the ion exchange membrane attached with the inorganic oxide coating at two sides thereof.

[0049] Under the same conditions as the example 1, the electrolytic test of NaCl aqueous solution is performed. After 23 days of electrolysis experiments, the average cell voltage is 2.91 V, the average current efficiency is 96.1%, the surface resistance is 2.4 .Math.cm.sup.2, and the wear loss is 11 mg.

Comparative Example 2

[0050] A same method as the example 1 is adopted to prepare an ion exchange membrane with ion exchange function. Differences are as follows. Before compounding with the perfluorinated ion exchange resin base film, the porous reinforcing material is not immersed into the fluorocarbon solvent, and after compounding with perfluorinated ion exchange resin base film, the porous reinforcing material is not processed through the overpressure machine. The perfluorinated ion exchange resin micro-particle dispersion liquid is prepared by a same method as the example 1, and then homogenized in a ball mill, and a dispersion liquid with a content of 15 wt % is formed. A same operation as the example 1 is performed to obtain an ion exchange membrane product.

[0051] Under the same conditions as the example 1, the electrolytic test of NaCl aqueous solution is performed. After 23 days of electrolysis experiments, the average cell voltage is 2.84 V, the average current efficiency is 99.1%, and the surface resistance is 1.7 .Math.cm.sup.2. Afterwards, 15 ppb inorganic matter Ca and Mg impurity are added to the NaCl aqueous solution; under the same conditions, after 40 days of electrolysis experiments, the average cell voltage is 2.94 V and the average current efficiency is 97.4%. A purity of the electrolytic product is as follows. A purity of chlorine gas is 98.5%, that of hydrogen gas is 98.6% and a content of salt in alkali is 16 ppm.

EXAMPLE 2

[0052] (1) Select perfluorosulfonic acid resin with IEC=1.1 mmol/g and perfluorocarboxylic acid resin with IEC=0.95 mmol/g; form a perfluorinated ion exchange resin base film in a co-extrusion and cast manner, wherein: in a resin layer mainly made of perfluorosulfonic acid resin, a weight ratio of the perfluorosulfonic acid resin to perfluorocarboxylic acid resin is 100:0.5; in a resin layer mainly made of the perfluorocarboxylic acid resin, a weight ratio of the perfluorocarboxylic acid resin to the to perfluorosulfonic acid resin is 100:0.5; the resin layer mainly made of perfluorosulfonic acid resin has a thickness of 100 m, and resin layer mainly made of the perfluorocarboxylic acid resin has a thickness of 15 m; and then immerse a porous reinforcing material polytetrafluoroethylene non-woven fabric in a mixed solvent of trifluoro-trichloroethane and anhydrous ethanol in an ultrasound processor for 1 hour, wherein: a thickness of the non-woven fabric is 30 m, a porosity is 65%; take out and dry the non-woven fabric; and then compound with the perfluorinated ion exchange resin base film; introduce a porous reinforcing material between two membrane forming rollers, press the porous reinforcing material into a membrane body under a pressure between the rollers, and form a perfluorinated ion exchange membrane precursor.

[0053] (2) Ultrasonically process the perfluorinated ion exchange membrane precursor obtained in the step (1) through an overpressure machine at 160 C. under a pressure of 100 tons with a speed of 40 m/min, and then immerse the perfluorinated ion exchange membrane precursor into a mixed aqueous solution comprising 15 wt % dimethyl sulfoxide and 20 wt % NaOH by weight at 85 C. for 80 minutes, and form a perfluorinated ion exchange membrane with ion exchange function.

[0054] (3) Prepare a mixed solution by mixing water and ethanol with a weight ratio of 1:1; add perfluorinated ion exchange resin micro-particles (which are obtained by crushing resin pellets for once in a low-temperature crushing device and then grinding in a cryogenic system) with IEC=1.0 mmol/g, an average particle size of 50 nm, and irregular polygon topography, into the mixed solution; and then homogenize in a ball mill, and form a dispersion liquid with a content of 15 wt %, wherein: the perfluorinated ion exchange resin micro-particles are a mixture of the perfluorosulfonic acid resin micro-particles, perfluorosulfonic acid carboxylic acid copolymer resin micro-particles and the perfluorocarboxylic acid resin micro-particles; a weight percentage of the perfluorosulfonic acid resin micro-particles in the mixture is 75%.

[0055] (4) Attach the dispersion liquid to a surface of two sides of the perfluorinated ion exchange membrane obtained in the step (2), wherein: a thickness of the surface layer is 50 nm; and form a product after drying.

[0056] Performance Testing:

[0057] An electrolytic test of the prepared ion exchange membrane about NaCl aqueous solution in an electrolysis cell is performed. 300 g/L NaCl aqueous solution is supplied to an anode chamber, water is supplied to a cathode chamber, it is ensured that a concentration of NaCl discharged from the anode chamber is 200 g/L, and a concentration of NaOH discharged from the cathode chamber is 35%; a test temperature is 90 C., a current density is 6.5 kA/m.sup.2; after 23 days of electrolysis experiments, the average cell voltage is 2.73 V and the average current efficiency is 99.6%.

[0058] Afterwards, 15 ppb inorganic matter Ca and Mg impurity are added to the NaCl aqueous solution; under the same conditions, after 40 days of electrolysis experiments, the average cell voltage is 2.73 V and the average current efficiency is 99.7%.

[0059] Based on standard SJ/T 10171.5, a surface resistance of the obtained membrane is tested to be 1.0 .Math.cm.sup.2; based on ASTM Standard D 1044-99, a wear loss of the obtained membrane is tested to be 2.8 mg.

[0060] According to electrolytic product testing standards, a purity of the electrolytic product is as follows. A purity of chlorine gas is 99.5%, that of hydrogen gas is 99.9% and a content of salt in alkali is 3 ppm.

EXAMPLE 3

[0061] (1) Select perfluorosulfonic acid resin with IEC=1.0 mmol/g and perfluorocarboxylic acid resin with IEC=0.9 mmol/g; form a perfluorinated ion exchange resin base film in a co-extrusion and cast manner, wherein: in a resin layer mainly made of perfluorosulfonic acid resin, a weight ratio of the perfluorosulfonic acid resin to perfluorocarboxylic acid resin is 100:3; in a resin layer mainly made of the perfluorocarboxylic acid resin, a weight ratio of the perfluorocarboxylic acid resin to the perfluorosulfonic acid resin is 100:2.5; the resin layer mainly made of perfluorosulfonic acid resin has a thickness of 150 m, and resin layer mainly made of the perfluorocarboxylic acid resin has a thickness of 7 m; and then immerse a porous reinforcing material polytetrafluoroethylene non-woven fabric in a mixed solvent of trifluoro-trichloroethane and propanol in an ultrasound processor for 1 hour, wherein: a thickness of the non-woven fabric is 10 m, a porosity is 50%; take out and dry the non-woven fabric; and then compound with the perfluorinated ion exchange resin base film; introduce a porous reinforcing material between two membrane forming rollers, press the porous reinforcing material into a membrane body under a pressure between the rollers, and form a perfluorinated ion exchange membrane precursor.

[0062] (2) Ultrasonically process the perfluorinated ion exchange membrane precursor obtained in the step (1) through an overpressure machine at 100 C. under a pressure of 20 tons with a speed of 10 m/min, and then immerse the perfluorinated ion exchange membrane precursor into a mixed aqueous solution comprising 15 wt % dimethyl sulfoxide and 20 wt % NaOH by weight at 85 C. for 80 minutes, and form a perfluorinated ion exchange membrane with ion exchange function.

[0063] (3) Prepare a mixed solution by mixing water and ethanol with a weight ratio of 1:1; add perfluorinated ion exchange resin micro-particles (which are obtained by crushing resin pellets for once in a low-temperature crushing device and then grinding in a cryogenic system) with IEC=0.8 mmol/g, an average particle size of 100 nm, and irregular polygon topography, into the mixed solution; and then homogenize in a ball mill, and form a dispersion liquid with a content of 15 wt %, wherein: the perfluorinated ion exchange resin micro-particles are a mixture of the perfluorosulfonic acid resin micro-particles, and perfluorosulfonic acid carboxylic acid copolymer resin micro-particles; a weight percentage of the perfluorosulfonic acid resin micro-particles in the mixture is 65%.

[0064] (4) Attach the dispersion liquid to a surface of two sides of the perfluorinated ion exchange membrane obtained in the step (2), wherein: a thickness of the surface layer is 400 nm; and form a product after drying.

[0065] Performance Testing:

[0066] An electrolytic test of the prepared ion exchange membrane about NaCl aqueous solution in an electrolysis cell is performed. 300 g/L NaCl aqueous solution is supplied to an anode chamber, water is supplied to a cathode chamber, it is ensured that a concentration of NaCl discharged from the anode chamber is 200 g/L, and a concentration of NaOH discharged from the cathode chamber is 32%; a test temperature is 90 C., a current density is 7.5 kA/m.sup.2; after 23 days of electrolysis experiments, the average cell voltage is 2.75 V and the average current efficiency is 99.7%.

[0067] Afterwards, 15 ppb inorganic matter Ca and Mg impurity are added to the NaCl aqueous solution; under the same conditions, after 40 days of electrolysis experiments, the average cell voltage is 2.75 V and the average current efficiency is 99.7%.

[0068] Based on standard SJ/T 10171.5, a surface resistance of the obtained membrane is tested to be 1.2 .Math.cm.sup.2; based on ASTM Standard D 1044-99, a wear loss of the obtained membrane is tested to be 2.7 mg.

[0069] According to electrolytic product testing standards, a purity of the electrolytic product is as follows. A purity of chlorine gas is 99.8%, that of hydrogen gas is 99.8% and a content of salt in alkali is 4 ppm.

EXAMPLE 4

[0070] (1) Select perfluorosulfonic acid resin with IEC=0.9 mmol/g and perfluorocarboxylic acid resin with IEC=0.85 mmol/g; form a perfluorinated ion exchange resin base film in a co-extrusion and cast manner, wherein: in a resin layer mainly made of perfluorosulfonic acid resin, a weight ratio of the perfluorosulfonic acid resin to perfluorocarboxylic acid resin is 100:5; in a resin layer mainly made of the perfluorocarboxylic acid resin, a weight ratio of the perfluorocarboxylic acid resin to the perfluorosulfonic acid resin is 100:4; the resin layer mainly made of perfluorosulfonic acid resin has a thickness of 75 m, and resin layer mainly made of the perfluorocarboxylic acid resin has a thickness of 18 m; and then immerse a porous reinforcing material polytetrafluoroethylene non-woven fabric in a mixed solvent of trifluorotrichloroethane and methanol in an ultrasound processor for 1.5 hours, wherein: a thickness of the non-woven fabric is 50 m, a porosity is 65%; take out and dry the non-woven fabric; and then compound with the perfluorinated ion exchange resin base film; introduce a porous reinforcing material between two membrane forming rollers, press the porous reinforcing material into a membrane body under a pressure between the rollers, and form a perfluorinated ion exchange membrane precursor.

[0071] (2) Ultrasonically process the perfluorinated ion exchange membrane precursor obtained in the step (1) through an overpressure machine at 200 C. under a pressure of 40 tons with a speed of 10 m/min, and then immerse the perfluorinated ion exchange membrane precursor into a mixed aqueous solution comprising 15 wt % dimethyl sulfoxide and 20 wt % NaOH by weight at 85 C. for 80 minutes, and form a perfluorinated ion exchange membrane with ion exchange function.

[0072] (3) Prepare a mixed solution by mixing water and ethanol with a weight ratio of 1:1; add perfluorinated ion exchange resin micro-particles (which are obtained by crushing resin pellets for once in a low-temperature crushing device and then grinding in a cryogenic system) with IEC=0.5 mmol/g, an average particle size of 200 nm, and irregular polygon topography, into the mixed solution; and then homogenize in a ball mill, and form a dispersion liquid with a content of 15 wt %, wherein: the perfluorinated ion exchange resin micro-particles are a mixture of the perfluorosulfonic acid resin micro-particles, and the perfluorocarboxylic acid resin micro-particles; a weight percentage of the perfluorosulfonic acid resin micro-particles in the mixture is 80%.

[0073] (4) Attach the dispersion liquid to a surface of two sides of the perfluorinated ion exchange membrane obtained in the step (2), wherein: a thickness of the surface layer is 700 nm; and form a product after drying.

[0074] Performance Testing:

[0075] An electrolytic test of the prepared ion exchange membrane about NaCl aqueous solution in an electrolysis cell is performed. 300 g/L NaCl aqueous solution is supplied to an anode chamber, water is supplied to a cathode chamber, it is ensured that a concentration of NaCl discharged from the anode chamber is 200 g/L, and a concentration of NaOH discharged from the cathode chamber is 30%; a test temperature is 90 C., a current density is 6.5 kA/m.sup.2; after 23 days of electrolysis experiments, the average cell voltage is 2.71 V and the average current efficiency is 99.8%.

[0076] Afterwards, 15 ppb inorganic matter Ca and Mg impurity are added to the NaCl aqueous solution; under the same conditions, after 40 days of electrolysis experiments, the average cell voltage is 2.71 V and the average current efficiency is 99.8%.

[0077] Based on standard SJ/T 10171.5, a surface resistance of the obtained membrane is tested to be 1.3 .Math.cm.sup.2; based on ASTM Standard D 1044-99, a wear loss of the obtained membrane is tested to be 2.8 mg.

[0078] According to electrolytic product testing standards, a purity of the electrolytic product is as follows. A purity of chlorine gas is 99.8%, that of hydrogen gas is 100% and a content of salt in alkali is 4 ppm.

EXAMPLE 5

[0079] (1) Select perfluorosulfonic acid resin with IEC=0.95 mmol/g and perfluorocarboxylic acid resin with IEC=0.85 mmol/g; form a perfluorinated ion exchange resin base film in a co-extrusion and cast manner, wherein: in a resin layer mainly made of perfluorosulfonic acid resin, a weight ratio of the perfluorosulfonic acid resin to perfluorocarboxylic acid resin is 100:3; in a resin layer mainly made of the perfluorocarboxylic acid resin, a weight ratio of the perfluorocarboxylic acid resin to the perfluorosulfonic acid resin is 100:5; the resin layer mainly made of perfluorosulfonic acid resin has a thickness of 50 m, and resin layer mainly made of the perfluorocarboxylic acid resin has a thickness of 10 m; and then immerse a porous reinforcing material polytetrafluoroethylene non-woven fabric in a mixed solvent of trifluoro-trichloroethane and acetone in an ultrasound processor for 1 hour, wherein: a thickness of the non-woven fabric is 10 m, a porosity is 85%; take out and dry the non-woven fabric; and then compound with the perfluorinated ion exchange resin base film; introduce a porous reinforcing material between two membrane forming rollers, press the porous reinforcing material into a membrane body under a pressure between the rollers, and form a perfluorinated ion exchange membrane precursor.

[0080] (2) Ultrasonically process the perfluorinated ion exchange membrane precursor obtained in the step (1) through an overpressure machine at 10 C. under a pressure of 60 tons with a speed of 1 m/min, and then immerse the perfluorinated ion exchange membrane precursor into a mixed aqueous solution comprising 15 wt % dimethyl sulfoxide and 20 wt % NaOH by weight at 85 C. for 80 minutes, and form a perfluorinated ion exchange membrane with ion exchange function.

[0081] (3) Prepare a mixed solution by mixing water and ethanol with a weight ratio of 1:1; add perfluorinated ion exchange resin micro-particles (which are obtained by crushing resin pellets for once in a low-temperature crushing device and then grinding in a cryogenic system) with IEC=0.3 mmol/g, an average particle size of 300 nm, and irregular polygon topography, into the mixed solution; and then homogenize in a ball mill, and form a dispersion liquid with a content of 15 wt %, wherein: the perfluorinated ion exchange resin micro-particles are a mixture of the perfluorosulfonic acid resin micro-particles, perfluorosulfonic acid carboxylic acid copolymer resin micro-particles and the perfluorocarboxylic acid resin micro-particles; a weight percentage of the perfluorosulfonic acid resin micro-particles in the mixture is 85%.

[0082] (4) Attach the dispersion liquid to a surface of two sides of the perfluorinated ion exchange membrane obtained in the step (2), wherein: a thickness of the surface layer is 1 m; and form a product after drying.

[0083] Performance Testing:

[0084] An electrolytic test of the prepared ion exchange membrane about NaCl aqueous solution in an electrolysis cell is performed. 300 g/L NaCl aqueous solution is supplied to an anode chamber, water is supplied to a cathode chamber, it is ensured that a concentration of NaCl discharged from the anode chamber is 200 g/L, and a concentration of NaOH discharged from the cathode chamber is 34%; a test temperature is 90 C., a current density is 5.5 kA/m.sup.2; after 23 days of electrolysis experiments, the average cell voltage is 2.70 V and the average current efficiency is 99.8%.

[0085] Afterwards, 15 ppb inorganic matter Ca and Mg impurity are added to the NaCl aqueous solution; under the same conditions, after 40 days of electrolysis experiments, the average cell voltage is 2.71 V and the average current efficiency is 99.8%.

[0086] Based on standard SJ/T 10171.5, a surface resistance of the obtained membrane is tested to be 1.1 .Math.cm.sup.2; based on ASTM Standard D 1044-99, a wear loss of the obtained membrane is tested to be 2.8 mg.

[0087] According to electrolytic product testing standards, a purity of the electrolytic product is as follows. A purity of chlorine gas is 99.8%, that of hydrogen gas is 99.8% and a content of salt in alkali is 3 ppm.