JPS6120637B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel and useful fluorine-based ion exchange membrane for electrolysis, and more specifically, it is a film-like material of a fluorine-containing polymer, and has -CFI- groups and/or -CF ₂ I as functional groups.
group and iodine is 4% (by weight) to 40% of the polymer
(by weight) % of a fluorine-based ion exchange membrane for electrolysis, and a method for producing the same. The establishment of an electrolysis method for aqueous alkali metal solutions using ion exchange membranes is widely desired as an alternative to the electrolysis of aqueous alkali metal salt solutions using the mercury method. In particular, ion exchange membranes for electrolysis are required to have chemical resistance and heat resistance, so fluorine-based ion exchange membranes are generally used. For example, a perfluorocarbon ion exchange membrane using a sulfonic acid group as an ion exchange group is known industrially under the trade name Nafion. The ion exchange groups in general ion exchange membranes include sulfonic acid groups, carboxylic acid groups, phosphoric acid groups, etc. Sulfonic acid groups are not necessarily sufficient ion exchange groups. On the other hand, fluorine-based ion exchange membranes having carboxylic acid groups as ion exchange groups are said to be excellent as ion exchange membranes for electrolysis.
However, since the carboxylic acid group itself lacks thermal stability, there are various difficulties when molding a film-like product of a fluorine-containing polymer having a carboxylic acid group. The present inventors have conducted intensive research on a method for producing a film-like product of a fluorine-containing polymer having a carboxylic acid group as a functional group. The present inventors have discovered a raw film in which carboxylic acid groups can be introduced and which is easy to handle, leading to the completion of the present invention. The present invention is a film-like material of a fluorine-containing polymer, which has a -CFI- group and/or a -CF ₂ I group as a functional group, and in which iodine accounts for 4% (by weight) to 40% (by weight) of the polymer. A raw membrane of a fluorine-based ion exchange membrane for electrolysis and a method for manufacturing the same, characterized in that: It is essential that the base film of the fluorine-based ion exchange membrane of the present invention is a film-like material of a fluorine-containing polymer and has a -CFI- group and/or a _-CF2I group as a functional group. These functional groups have the advantage that they can be easily converted into carboxylic acid groups by hydrolysis after reaction with mineral acids such as sulfuric acid, chlorosulfonic acid, and nitric acid. however,
When the ion exchange membrane obtained from the raw membrane is used as an ion exchange membrane for electrolysis, it is necessary that the ion exchange membrane has properties such as electrical resistance and strength of the membrane itself that are suitable for practical use. Therefore, the iodine present in the raw film of the present invention is 4% (by weight) to 4% (by weight) of the polymer.
It is important to account for a range of 40% (by weight). If the iodine content is less than 4% (by weight), the electrical resistance of the resulting ion exchange membrane will be high, making it undesirable as an ion exchange membrane for electrolysis. On the other hand, if the iodine content is more than 40% (by weight), the resulting ion exchange membrane will not have sufficient strength for practical use and its electrochemical properties will be poor, which is not preferable. The -CFI- group and/or -CF ₂ I functional group present in the raw membrane of the fluorine-based ion exchange membrane of the present invention may be uniformly distributed and bonded within the membrane of the raw membrane. It may be present biased towards at least one surface layer. Of course, the fact that other ion exchange groups or other functional groups that can easily become ion exchange groups by post-treatment, such as sulfonyl halide groups and sulfonic acid groups, are bonded to the functional group is a hindrance to the present invention. isn't it. In addition, the fluorine-containing polymer film is preferably a perfluorocarbon polymer from the viewpoint of acid resistance, heat resistance, chemical resistance, etc., but the acid resistance, heat resistance, chemical resistance, etc. It is acceptable even if it contains chlorine, hydrogen, or hydrocarbon groups to the extent that it can be subjected to Generally, it is most preferable that the functional group is bonded to a side chain, and a perfluorocarbon side chain is formed in the main chain of the perfluorocarbon polymer, and the functional group is bonded to the end of the side chain. and preferable. Further, the functional group may be bonded via an ether bond, a thioether bond, or a fluorine-containing alkyl group. The film-like material of the fluorine-containing polymer and the manufacturing method thereof in the present invention are not particularly limited, and known materials or manufacturing methods can be employed. For example, the special public interest public in 1973
No. 22327, Japanese Patent Publication No. 1972-26303, Japanese Patent Publication No. 1973-108182
The film-like material or its manufacturing method described in Japanese Patent Application Laid-open No. 52-36589 and the like can be suitably employed. More specific examples of these methods are as follows. (a) General formula Fluorine-containing monomer (b) represented by the general formula Fluorine-containing monomer (c): Fluorophine such as tetrafluoroethylene, hexafluoropropylene, trifluoro-chlorinated ethylene, vinylidene fluoride, vinyl fluoride, alkyl vinyl ether, etc. However, in the above formulas () and (), X is hydrogen, a halogen atom, or a fluoroalkyl group; Y is a fluorine atom or a perfluoroalkyl group; Z is an ion exchange group or a functional group that can be converted into an ion exchange group; l is 0 ~5; m and m' are each 0 or 1; n is 1~
12 are shown respectively. A fluorine-containing monomer represented by the above general formula () and
A fluorine-containing polymer can be obtained by solution polymerization or suspension polymerization of (c) fluoroolefin in the presence of a radical polymerization initiator. Of course, when a film-like product of the fluorine-containing polymer is to be obtained, it can be obtained by a known method such as molding at the same time as the above polymerization or molding after obtaining the polymer. Also, the general formula ()
When the fluorine-containing monomer represented by the formula (2) is used in place of the fluorine-containing monomer () above, it can be a fluorine-containing polymer having an unsaturated bond at the end of the main chain or side chain. Of course, fluorine-containing polymers obtained using as starting materials a monomer mixture consisting of the fluorine-containing monomers represented by the above general formulas () and () and the fluoroolefin shown in the above (c) can also be suitably used. In addition, when obtaining a fluorine-containing polymer having a sulfonyl halide group as a functional group to be used as a raw material in the method for producing the raw film of the present invention, the above-mentioned fluorine-containing monomer having a sulfonyl halide group as a functional group is used to carry out the polymerization. Alternatively, after obtaining the fluorine-containing polymer, a sulfonyl halide group may be introduced as a functional group in a post-treatment. Some of the methods for obtaining the raw film of the present invention have been described above, but there are no particular limitations and any known method can be employed. A typical method will be explained below. One of the most typical industrial methods is to react a fluorine-containing polymer having a sulfonyl halide group as a functional group with iodine or an iodine-containing compound to form a -CFI- group or -CF ₂ I group in the polymer. This is a method of introducing Furthermore, by reacting a fluorine-containing polymer having an unsaturated bond at the end of the main chain or side chain with iodine or an iodine-containing compound, a -CFI- group or a -CF ₂ I group can be introduced into the polymer. I can do it. A film-like product formed from a fluorine-containing polymer or a powder may be used, but when such a powder is used, it is necessary to form it into a film after the above-mentioned reaction. Of course, a method for obtaining a film-like material by polymerizing or copolymerizing a monomer having a polymerizable unsaturated bond and a vinyl monomer having a -CFI- group or _-CF2 ,
A method of uniformly or non-uniformly mixing an oligomer or fluorine-containing polymer having -CFI- groups and/or -CF ₂ I groups with other fluorine-containing polymers and forming the mixture into a film-like material may be used as necessary. Can be hired. In short, at the end of the main chain or side chain -CFI-
The fluorine-containing polymer for introducing groups and/or -CF ₂ I groups is a polymer having a sulfonyl halide group in the main chain or side chain F ₂ C=CX(O) _n -(CF ₂ ) _o -(O ) _n −CX=
A polymer having a double bond in the side chain obtained by copolymerizing CF ₂ (m and n are the same as above) F ₂ C=CF−CF=CF ₂ or

[Formula] A polymer having a double bond in the main chain by copolymerizing monomers having a conjugated double bond such as A polymer in which double bonds are formed in the main chain by eliminating FCl A polymer that can react with other iodine or iodine-containing compounds such as hydrogen iodide is used. When iodine is reacted with a fluorine-containing polymer having a sulfonyl halide group, for example, a sulfonyl fluoride, sulfonyl chloride, sulfonyl bromide, or sulfonyl iodide group, the fluorine-containing polymer may be reacted with iodine vapor by contacting a film of the fluorine-containing polymer. Therefore, it can be easily used as the raw film of the present invention. Of course, the reaction with iodine can also be carried out in the form of a solution, which is generally suitable for controlling the reaction. For example, the conditions for reacting iodine with a film of a fluorine-containing polymer having a sulfonyl halide group are, for example, under normal pressure to elevated pressure.
What is necessary is just to carry out in the range of 30-300 degreeC. When an iodine-containing compound is used, the reaction may be carried out in a solvent capable of dissolving the iodine-containing compound, such as alcohol, acetonitrile, diglyme, or carbon disulfide. Further, the method for reacting iodine or an iodine-containing compound with a film of a fluorine-containing polymer having an unsaturated bond at the end of its main chain or side chain is not particularly limited, and any known method can be employed. For example, an addition reaction of iodine or an iodine-containing compound to the above-mentioned fluorine-containing polymer may be carried out in the presence or absence of a suitable solvent in the presence of heat, light, ionizing radiation, a radical initiator or other catalyst.
Examples include irradiation with ultraviolet rays in the presence of elemental iodine vapor, heating, irradiation with ionizing radiation, heat treatment in the presence of elemental iodine and a radical initiator, and irradiation of elemental iodine with organic Dissolved in a solvent (preferably alcohol, carbon disulfide)
If two or more methods are used in combination, such as heating to 50℃ or higher, irradiating with visible light or ultraviolet rays in the presence of a photosensitizer, or heating in the presence of a radical initiator and simultaneously irradiating with ultraviolet rays, etc. Particularly favorable results are obtained. Generally, when only heat is used, it is 0°C.
The above temperature range is preferably 50° C. or higher, at which the membrane of the fluorine-containing polymer does not decompose. When using light, ultraviolet light is preferred, but it is not necessarily necessary to use ultraviolet light, and visible light may be used with a sensitizer co-promoting. In this case, conventionally known photosensitizers may be used without any restriction, and may be appropriately selected depending on the purpose. Ionizing radiation is α, B, γ, X
The optimum irradiation dose is selected within the range of 0.1 to 30 Mrad, but it must be carried out within a range that does not cause significant decomposition of the fluorine-containing polymer film or decrease in mechanical strength. There must be. In addition, conventionally known organic and inorganic radical initiators can be used without limitation, and organic ones can be appropriately selected and used such as hydrocarbon-based, fluorine-containing, perfluorinated, etc. Half-life of decomposition is 40℃
There is no limit as long as it is more than 10 hours. Specifically, benzoyl peroxide, α, α′-
Azobisisobutyronitrile, lauryl peroxide, ditertiary butyl peroxide,
Examples include N ₂ F ₂ and CF ₃ COOCF ₃ , but these are merely examples. In addition, when a fluorine-containing polymer having an unsaturated bond is reacted with iodine or an iodine-containing compound, elemental iron, iron salts, etc. are used as suitable catalysts. Even more effects can be obtained when one or more of these heat, light, ionizing radiation, radical initiators, catalysts, etc. are used in combination, but the conditions must be selected and carried out under conditions that allow the reaction to proceed most efficiently. do it. As mentioned above, the iodine mentioned above can be in elemental form, gaseous form,
It may be in the form of a solution or a solid, and its concentration is not particularly limited, but it is usually used from 0.001% to a saturated solution. One of the solvents used when the solution is in the form of a solution is selected so as to dissolve iodine and to control the degree of reaction to the fluorine-containing polymer. For example, when reacting only near the surface of a fluorine-containing polymer film, use a solvent that does not have good affinity for the film to react only at the surface of the film, and even to the inside of the film. When the reaction is to proceed, it is preferable to use a solvent that has good affinity for the membrane-like material and can swell it well. Inorganic and organic iodine salts are used as the iodine-containing compound. Inorganic iodine salts include cationic alkali metal salts, alkaline earth metal salts, transition metal iodine salts,
There are no particular restrictions on complex salts, etc. More specific examples include sodium iodide, potassium iodide, lithium iodide, cesium iodide, calcium iodide,
Suitable examples include magnesium iodide, strontium iodide, cobalt iodide, nickel iodide, iron iodide, and copper iodide. In addition, as organic iodine salts, organic substances with cations bound to so-called onium bases such as primary, secondary, and tertiary amines, quaternary ammonium bases, arsonium bases, phosphonium bases, stibonium bases, and sulfonium bases are used. The organic chain of the amine is not particularly limited, such as a saturated or unsaturated linear alkyl group, a branched chain alkyl group, a cyclic chain, a chain having an aromatic ring, or a chain having a heterocycle. More specific examples include iodide salts of alkylammonium such as tetramethylammonium iodide, hydroiodide of aniline, hydroiodide of diethylamine, hydroiodide of triethanolamine, and iodide of triethylamine. Hydrogen salt,

[Formula] [(CH ₃ ) ₄ Sb] ⁺ I ^-

[Formula] etc. are suitable. Furthermore, the iodine compound in the present invention is not in the form of a salt, but is also effective in which iodine is bonded to a halogen compound such as bromine or chlorine through a covalent bond. -CFI- group or -CF ₂ I bonded to the main chain or side chain of the fluorine-containing polymer membrane thus obtained
The group is ( _-CF2 -CFI-CFI- _CF2 )-

【formula】

or It takes the form of These -CFI- groups or -
The CF ₂ I group can be converted into a carboxylic acid group, for example, by mineral acid, alkali treatment, Grianyl reagent reaction, introduction of CO ₂ , etc. The contents of the present invention will be specifically explained with reference to the following examples, but the contents of the present invention are not limited to the following examples. Regarding the various properties when the raw film of a fluorine-based ion exchange membrane having -CFI- group and/or -CF ₂ I group as a functional group, which is shown as an application example in the examples, is further processed and converted into a carboxylic acid group. I used the following method. That is, the electrical resistance is 3.5N−NaCl and 6.0N−
This value was measured by placing NaOH on both sides of the membrane and applying alternating current for 1000 cycles at 85°C. The exchange capacity is determined by immersing the membrane in acid form in a fixed amount of 0.1N-NaOH.
After standing for a period of time, the amount of NaOH neutralized by the acid in the membrane was determined by back titration with 0.1N HCl.
It is expressed in weight per (H type). The water content was measured at room temperature after boiling in pure water at 100°C for 30 minutes, and was expressed as the amount (%) per 1 g of H-type dry film. For the electrolysis experiment, an electrolytic cell with an effective current-carrying area of 1 dm ² was used. The anode was a regular metal anode made of titanium lath coated with titanium dioxide and ruthenium dioxide, and the cathode was a soft iron wire mesh. The membrane was supported by the anode, and the gap between the cathode and the membrane was maintained at approximately 3 mm. The temperature during electrolysis is kept at 80 to 90℃, and pure water is supplied to the cathode chamber to maintain a constant concentration of NaOH.
is now obtained regularly. A saturated alkali metal solution was supplied to the anolyte, and in the case of saline solution, it was discharged at approximately 3.0 to 3.5N. In addition, the sum of both Ca ⁺⁺ Mg ⁺⁺ in the brine used was suppressed to 1 ppm or less. Further, the current density during electrolysis was 30 A/dm ² unless otherwise specified. Example 1 Tetrafluoroethylene and perfluoro(3,
6-dioxa-4-methyl-7-octensulfonyl fluoride) was copolymerized and then formed into a film (thickness 0.15 mm), which was then hydrated by dissolving NaOH in a mixed solvent of dimethyl sulfoxide and water. A perfluorosulfonic acid type cation exchange membrane was obtained by immersing it in a decomposition bath and undergoing hydrolysis treatment. Exchange capacity is
It was 0.91 meq/g dry film (OH type). This was immersed in 20% nitric acid at 80°C for 16 hours to convert it to the sulfonic acid form, and then phosphorus oxychloride 2
and phosphorus pentachloride 1 at 130°C for 72 hours to convert the sulfonic acid groups into sulfonyl chloride groups. In order to see the rate of conversion of this into a sulfonyl chloride group, the electrical resistance was measured at 1000 cycles of alternating current in 1.0N-HCl and was approximately 45000 at 25.0℃.
It was Ω- ^cm2 . Next, this membrane was immersed in a solution prepared by dissolving 3 parts of ditertiary butyl peroxide in 100 parts of an ethanol saturated solution of iodine in an autoclave at room temperature and left for 16 hours to fully impregnate the membrane.
Heat treatment was performed at 130°C for 24 hours in an oil bath. After cooling, the film was taken out and thoroughly washed with ethanol and then with carbon disulfide. When the reflection infrared absorption spectrum of the surface was taken, the absorption at 1420 cm ^-1 corresponding to sulfonyl chloride had disappeared. Therefore, when the surface layer of this film was scraped off with a razor and subjected to elemental analysis, the amount of iodine was found to be 8.9%. Furthermore, the amount of iodine was determined by elemental analysis of not only the surface layer but also the film itself, and it was found to be 5.3%. Application example 1 The raw film obtained in Example 1, that is, a film of perfluoro polymer bound with iodine, was immersed in a large excess of oleum containing 30% excess sulfur trioxide at 130°C for 100 hours. After that, it was allowed to cool, and then it was sequentially immersed in 98%, 80%, and 40% sulfuric acid water, and finally it was immersed in a 10% NaOH methanol solution. When the surface of the obtained film-like material was observed using a reflection infrared absorption spectrum, approx.
Strong absorption of 1690 cm ^-1 was observed. Also about 1060cm
^-1 was confirmed as a weak shoulder absorbing sulfonic acid. When we measured the electrical resistance of the above membrane, it was 1.95Ω- when it was still a sulfonic acid type membrane.
cm ² , exchange capacity 0.91 meq/g dry membrane (H type), water content 17%, and calculated fixed ion concentration was 5.26 m. On the other hand, the membrane produced by the method of the present invention has an exchange capacity of 0.88 meq/g dry membrane (H type), a water content of 12%, and a fixed ion concentration of 733.
It became m. However, the electrical resistance increased to 3.92Ω-cm ² . In addition, after reacting with iodine, reacting with fuming sulfuric acid, and then only hydrolyzing, the membrane was stained with crystal violet, and when the thickness of the stained membrane was observed under a microscope, 1/3 of each side of the membrane was extremely clear. The central 1/3 of the stain was only slightly stained. Next, when this membrane was used to electrolyze saturated saline at 20 A/dm ² using the apparatus described in the specification, the cell voltage was
3.52V, current efficiency is 61% with 6.0N-NaOH
However, in the case of the membrane of the present invention, the cell voltage
4.05V, current efficiency is 94% with 8.7N−NaOH obtained.
It was hot. Also, the amount of NaCl in NaOH is 48% in the former.
What was 145ppm in terms of NaOH became 17ppm. Example 2 A polymer obtained by suspension polymerization of CF ₂ =CFOCF ₂ CF = CF ₂ was molded into a sheet with a thickness of 0.15 mm. This sheet (10 cm x 15 cm) was heated in a 500 c.c. glass autoclave with 1 g of FeCl ₃ and 100 g of ICl.
The mixture was reacted with cc of methylene chloride at 5°C for 10 hours. After the reaction, the sheet was thoroughly washed with methylene chloride. After washing, elemental analysis of the sheet revealed that it was a film of a fluorine-containing polymer containing 23% iodine. Application example 2 After immersing the fluorine-containing polymer film obtained in Example 2 in chlorosulfonic acid at 130°C for 150 hours, 10%
It was immersed in a NaCH aqueous solution for hydrolysis treatment. The exchange capacity of the resulting membrane was 0.89 meq/g dry membrane (H type). A dyeing test with crystal violet revealed that the dyeing was almost uniform. The electrical resistance of this membrane was 4.2 Ω-cm ² , and electrolysis of saturated saline solution was carried out at 20 A/dm ² using the apparatus described in the specification. The current efficiency was 92% when 12N-NaOH was obtained from the cathode. Example 3 The same perfluoroalkyl vinyl ether sulfonyl fluoride film used in Example 1 was similarly treated with phosphorus oxychloride and phosphorus pentachloride to convert it into a sulfonyl chloride group. This was placed in a desiccator containing a mercury ultraviolet lamp, and at the same time solid iodine was sealed, the pressure was reduced, the mixture was sealed, and the mixture was placed in an oil bath and heated to 85°C to saturate the desiccator with iodine vapor. 8
After leaving it for a while, it was irradiated with an ultraviolet lamp for 16 hours. The ultraviolet lamp used was a Toshiba ultraviolet lamp SHLS-1002B. After cooling, remove the membrane and wash with methanol.
Next, after reflux cleaning with carbon disulfide, the amounts of iodine and sulfur in the surface layer were similarly measured using fluorescent X-rays, and it was found that about 84% of the -CF ₂ SO ₂ Cl groups in the surface layer were -
It was confirmed that it was converted to a CF ₂ I group. However, in this case, only the surface irradiated with ultraviolet rays was significantly more visible, and some light was also observed on the back surface (−CF ₂ SO ₂ Cl
(approximately 3.5% of the group) This is thought to be due to iodine being adsorbed to the film-like material or due to the reaction progressing due to heat. Application example 3 The fluorine-containing polymer film obtained in Example 3 was
After thoroughly drying the film-like material under reduced pressure and degassing it in ethyl ether of C ₃ H ₇ MgBr, it was immersed at -30°C, left for 8 hours, and then further cooled to -40°C and thoroughly dried. Dehydrated and purified CO ₂ was introduced into the solution, bubble-stirred, and left for 24 hours so that the CO ₂ came into sufficient contact with the surface of the film-like material. After returning to room temperature, the film-like material was taken out and washed with methanol and then with water. Soaked in NaOH. When we took a reflection infrared absorption spectrum of the surface layer of this film on the side irradiated with ultraviolet rays, an extremely strong absorption peak appeared at 1690 cm ^-1 , indicating that carboxyl groups were formed. Furthermore, when the ultraviolet irradiated surface of the film reacted with this Grignard reagent was analyzed using fluorescent X-rays, only the same amount of iodine as the background was detected. Application example 4 After immersing the membrane obtained in Application example 3 in a 10% NaOH methanol solution at 60°C for 16 hours, this membrane was used as a cation exchange membrane to conduct a salt electrolysis cell as described in the specification. When saturated saline was electrolyzed (with the ultraviolet irradiated surface facing the cathode), the result was 7.3−
NaOH was obtained and the cell voltage was 3.84 V at a current density of 30 A/dm ² . On the other hand, the sulfonic acid type cation exchange membrane that has not been treated according to the present invention has a low electrode voltage.
It was 3.81V. The current efficiency is 92% for the former and 92% for the latter.
It was 51%. Also, the amount of NaCl in NaOH is 48%
In terms of NaOH, the former was 18 ppm, while the latter was 148 ppm. Further, when a dyeing test was carried out by immersing the film-like material before being immersed in the 10% NaOH methanol solution in an aqueous solution of crystal violet, which is a basic dye, the surface layer was extremely dyed up to about 1.2 microns. The back side was slightly stained, approximately 0.1 microns thick. Example 4 A fluorine-containing polymer obtained by suspension polymerization of CF ₂ =CF-OCF ₂ CF ₂ -CF=CF ₂ was molded into a film with a thickness of 0.15 mm. This was immersed in a saturated solution of iodine in ethyl alcohol and left for ²⁴ hours to fully impregnate iodine into the film. After being irradiated with six different doses shown in the table, each sample was taken out and thoroughly washed with ethanol, and then with carbon disulfide to remove adsorbed and attached iodine. This was subjected to elemental analysis to determine the amount of iodine. The result is the first
It was as shown in the table.

[Table] Application Example 5 The films of each iodine-bonded fluorine-containing polymer obtained in Example 4 were immersed in chlorosulfonic acid with a purity of 90% or more at 130°C for 200 hours. Next, this was immersed in a 1:1 mixed solution of 10% NaOH in water and ethanol to be hydrolyzed to obtain a cation exchange membrane having carboxylic acid groups. The properties of this cation exchange membrane and electrolysis of saturated saline were investigated. The results are shown in Table 2.

[Table] Membrane No. 6 had extremely low mechanical strength. Example 5 When a membrane of the same copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether sulfonyl fluoride used in Example 1 was hydrolyzed, the exchange capacity was 0.91 meq/g of the dry membrane (H type). The material was heat-treated at 135° C. for about 75 hours in a mixture of PBr ₃ and PBr ₅ at a ratio of 3:1 to form a sulfonyl bromide film.
To check the degree of conversion from sulfonic acid to sulfonylbromide, we measured the electrical resistance in 1.0N-HCl with 1000 cycles of alternating current, and found that it was approximately 31000Ω (at 25°C).
^-cm2 . A solution of 3 parts of ditertiary butyl peroxide dissolved in a mixed solution of 20 parts of iodine and 100 parts of ethanol was coated uniformly on one side of this, and the mixture was soaked into the inside of a certain grade film. Cover with cellophane, scissors between iron plates 110
Heat treatment was performed at ℃ for 18 hours. The film-like material taken out after cooling was extracted with ethanol and carbon disulfide to remove adsorbed or attached iodine, and the amount of iodine and sulfur was determined using fluorescent X-rays. S in the surface layer decreased to about 1/5 of the original amount, and iodine was bound in an amount equivalent to about 3/5 of the exchange capacity of the membrane. Example 6 A film of the copolymer of perfluoralkyl vinyl ether sulfonyl fluoride and tetrafluoroethylene prepared in Example 1 was immersed in a solution of hydrazine in carbon tetrachloride and allowed to react at 50°C to form sulfonic acid. hydrazide was formed. This was added to a solution of iodine dissolved in carbon tetrachloride to a saturated state, and the mixture was heated in an autoclave at 115°C for 24 hours. After cooling, the film-like material was taken out and washed with water, ethanol, and carbon disulfide, and then examined using fluorescent X-rays.
When the amount of Cl was determined, 85% of the original film-like substance had disappeared and the amount of sulfur had been reduced by 8%. On the other hand, a new amount of iodine was observed that was approximately equal to the amount of chlorine reduced. After reducing the pressure and heating it at 180°C for 16 hours, we further determined the amounts of Cl, S, and I. We found that the amount of sulfur was significantly reduced, and 95% of the original film-like substance disappeared, and the proportion and presence of Cl and I were determined. The amount did not change much. It seems that the reaction -CF ₂ SO ₂ I → -CF ₂ I + SO ₂ ↑ probably progressed. Example 7 CF ₂ = CF−CF ₂ −CF=Fine powder of polymer obtained by suspension polymerization of CF and finely divided calcium carbonate were added at a ratio of 1:2.
The mixture was mixed under heat and pressure to form a film-like product. After stretching this by 1.2 times both vertically and horizontally
It was immersed in 5.0N-HCl at 60°C for 48 hours. Calcium carbonate inside the membrane was decomposed and removed to form a porous membrane. When this membrane-like material was air-dried and the amount of pure water permeated was examined, no water permeability was observed up to a pressure of 1 m of water column. The membrane itself was water repellent and completely impermeable to water. Next, this was immersed in a solution of 20 parts of iodine in 100 parts of carbon disulfide and left until the iodine had sufficiently penetrated into the film (48 hours).
Gamma rays were irradiated from a source of 7.5 MradCO ⁶⁰ at 3800 rad/hr. Elemental analysis revealed 8.8% iodine. Application example 6 The microporous membrane obtained in Example 7 was treated with fuming sulfuric acid containing an excess of 30% SO ₃ at 120°C and 120°C in the same manner as in Example 1.
The mixture was allowed to react for a time and then immersed in a 10% NaOH aqueous solution. This porous membrane was found to have cation exchange capacity and was clearly stained with crystal violet. It had extremely good hydrophilicity, with a water permeability of 0.12 cc/hr·cm ² ·cmH ₂ O. Furthermore, when an infrared absorption spectrum was taken of a part of this, a strong absorption at 1690 cm ^- ₁ corresponding to the -CF ₂ COONa group was observed, and an absorption at 1790 cm ^- ₁ which was thought to be assigned to the -CF=CF ₂ group was observed. Absorption was observed. Therefore, when this was further heated at 130℃ for 100 hours while irradiated with ultraviolet rays from a high-pressure mercury lamp and the infrared absorption spectrum was taken again, the absorption at 1790 cm ^-1 decreased significantly and the water permeation rate was 0.08 cc/hr・cm ²・cmH ₂ O and the film had become slightly hard. This seems to be due to the formation of a crosslinked structure. Example 8 CF ₂ =CFO(-CF ₂ )- ₃ COOH was reacted with Br ₂ while irradiated with ultraviolet rays to add bromine to the double bond. Next, 100 parts of a solution of 10% iodine dissolved in ethyl alcohol was placed in an autoclave, and 50 parts of the above-mentioned bromine-added carboxylic acid group-containing compound was added thereto, followed by heating at 180°C for 8 hours. Then, the ethyl alcohol was removed and the mixture was distilled.
As a result, _CF2Br −CFBrO( _−CF2 ) _−3I was obtained with a yield of 15%.
I got it. This is added to a dispersion of zinc powder in methyl alcohol to debromine, and CF ₂ = CF-O
(−CF ₂ )− ₃ I was obtained. The monomer obtained above and tetrafluoroethylene were copolymerized using 1,1,2-trichlorotrifluoroethane as a solvent and α,α″-1 azobisisobutyronitrile as a polymerization initiator. The obtained polymer Elemental analysis revealed that iodine was 36.5%
It was included. Next, this was placed between hot plates and heated and pressurized to obtain the film-like material of the present invention. A portion of this film-like material was cut out and ground into fine powder using a coffee mill. Elemental analysis of iodine was again conducted, and it was found to be 28.5%.

Claims (1)

[Scope of Claims] 1. A film-like material of a fluorine-containing polymer, which has - as a functional group.
A fluorine-based ion exchange membrane for electrolysis, characterized in that it has a CFI group and/or a -CF ₂ I group, and iodine accounts for 4% (by weight) to 40% (by weight) in the polymer. protomembrane. 2. The raw film according to claim 1, wherein the fluorine-containing polymer is a perfluorocarbon polymer. 3. A powder or film of a fluorine-containing polymer having a sulfonyl halide group as a functional group is reacted with iodine or an iodine-containing compound to introduce a -CFI- group and/or a -CF ₂ I group into the polymer. 1. A method for producing a base membrane of a fluorine-based ion exchange membrane for electrolysis, characterized in that the fluoropolymer powder is then formed into a membrane-like material. 4 -CFI- group and/or _-CF2I group is introduced into the fluorine-containing polymer as iodine in a range of 4 (weight)% to 40 (weight)% of the raw film according to claim 3. Production method. 5. The method for producing a raw film according to claim 3, wherein the fluorine-containing polymer is a perfluorocarbon polymer. 6. A powder or film of a fluorine-containing polymer having an unsaturated bond at the end of the main chain or side chain is reacted with iodine or an iodine-containing compound to add -CFI- groups and/or
Or - A method for producing a base film of a fluorine-based ion exchange membrane for electrolysis, which comprises introducing a CF ₂ I group and then forming the powder of the fluorine-containing polymer into a membrane. 7 -CFI- group and/or _-CF2I group is introduced into the fluorine-containing polymer as iodine in a range of 4% (by weight) to 40% (by weight) of the raw film according to claim 6. Production method. 8. The method for producing a base film according to claim 6, wherein the fluorine-containing polymer is a perfluorocarbon polymer.