JPS5941336A - Preparation of composite membrane - Google Patents

Abstract

PURPOSE:To prepare a composite membrane suitable as an electrolytic membrane capable of keeping high current efficiency for a long period, by applying fine powder of a polylmer compound and a vinyl monomer to the surface of a fluorine-containing cation exchange membrane, etc., and polymerizing the monomer thereby bonding the polymer to the membrane. CONSTITUTION:Fine powder of a polymer compound (e.g. ethylene, ethylene oxide, etc.) having a particle diameter of preferably 0.01-10mu is dispersed in a vinyl monomer (e.g. styrene) to obtain a dispersion composed of 0.5-50wt% of the polymer compound and 5-80wt% of the vinyl monomer. The dispersion is applied to the surface of a polymer membrane having fluorine atom and cation exchange group (e.g. sulfonic acid group) or a functional group (e.g. acid ester group) to which a cation exchange group can be introduced easily, by impregnation or coating. The vinyl compound is polymerized on the surface of the membrane, and if necessary, ion exchange group is introduced to the product to obtain the objective composite membrane.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a method for producing a diaphragm for electrolysis, and its purpose is to obtain a composite ion exchange membrane made of fluorine-containing threads that can maintain high current efficiency for a long period of time.

As a diaphragm to be used in the electrolysis of alkali metal salts or in other atmospheres where oxidative debris is generated, it has been proposed to use cationic catalytic resins that selectively transmit cations. Today, the product name for this type of diaphragm is N.
There is a fluorine-containing cation exchange membrane called afion, which is obtained by copolymerizing perfluorovinyl ether sulfonyl fluoride with tetrafluoroethylene, and has outstanding oxidation resistance. However, when the fluorine-containing thread cation exchange membrane is used as a diaphragm for the electrolysis of alkali metal salts, the current efficiency is low (unsatisfactory). A method in which graft polymerization of perfluoro (sulfonyl fluoride) or perfluoro (alkyl vinyl ether sulfonic acid), etc. is performed using ionizing radiation, and a method in which perfluoro (furkyl vinyl ether carboxylic acid), etc. is grafted onto a fluorine-containing polymer film using ionizing radiation. A cation exchange membrane containing a polymer having a carboxylic acid group and a fluorocarbon polymer has been proposed. We are aiming to develop a diaphragm for electrolysis that can obtain alkali metal hydroxides with high current efficiency.However, like general ion exchange membranes, these fluorine-containing cation exchange membranes have problems when used continuously for long periods of time. Even if the exchange capacity decreases slightly, the water content increases significantly, so the fixed ion concentration in the membrane decreases over time, which in turn causes a decrease in current efficiency. It is presumed that this is due to the fact that ions in the membrane permeate through electricity, and the polymer chains in the membrane loosen over time due to heat generation and other factors.For this reason, the membrane must have a cross-linked structure as uniformly and highly as possible. Although it is desirable to form a film, it is unavoidable that the electrical resistance of the film becomes significantly high.
As a method for suppressing the above-mentioned loosening of polymer chains over time without significantly increasing electrical resistance, the present inventors developed a polymer to which fluorine atoms were first bonded and cation exchange groups were bonded. Although it was proposed to impregnate and polymerize a vinyl monomer into a film-like material, its durability was still unsatisfactory in a high-temperature atmosphere for a long period of time.

From the above point of view, the inventors of the present invention have conducted further intensive research on membranes that exhibit significantly less deterioration in performance even during long-term electrolysis in high-temperature atmospheres, and have developed a new composite membrane. This method was developed using the R-mailing method. That is, the present invention provides a method for forming a particulate polymer compound and a vinyl monomer on the surface of a polymer membrane in which a fluorine atom and a cation exchange group or a functional group into which a cation exchange group can be easily introduced in post-treatment are bonded. This is a method for producing a composite membrane, which is characterized by polymerizing the vinyl monomer in the presence of and introducing an ion exchange group as necessary.

The reason why the composite cation exchange membrane obtained by the present invention exhibits extremely excellent performance, especially as a diaphragm for electrolysis, is not necessarily clear. Normally, when the fixed ion concentration of a cation exchange membrane is low in a concentrated electrolyte aqueous solution, the cation exchange membrane becomes so strong that even trapped ions permeate through the cation exchange membrane.

Therefore, in order to use an ion exchange membrane suitable for a concentrated electrolyte aqueous solution system, an ion exchange membrane with a significantly high fixed ion concentration is required. The present inventors have previously found that the 'ih flow efficiency is significantly improved when an ion exchange membrane is placed in a dehydrated atmosphere.Furthermore, this phenomenon is extremely pronounced in electrolytic diaphragms that have fluorine atoms bonded to them. be. For example, tetrafluoroethylene and perfluoro(3,6-
A perfluorosulfonic acid type cation exchange membrane obtained by copolymer hydrolysis of Shiokizer (4-methyl-7-ocgunsulfonyl fluoride) was left in a dry state at 120°C for a long period of time to remove alkali metals. When used for electrolysis of a salt aqueous solution, such as saturated saline, 20% sodium hydroxide can be obtained and the current efficiency can reach as high as 95%. Furthermore, when the same membrane is boiled in pure water, 20% strength soda is obtained, and the current efficiency is only 65%. It is presumed that such a drastic change in membrane performance is due to the increase in membrane water content due to the change in hydrophobic binding force, resulting in a decrease in the concentration of identified ions. Of course, if a diaphragm whose current efficiency has been improved by heating and pressurizing is subjected to electrolysis for a long time of 9 hours, its current efficiency will gradually decrease and the properties will become the same as those of the membrane treated by boiling. Such a phenomenon is observed to varying degrees even in ion exchange membranes having a three-dimensional structure. From this point of view, in this paper, we will discuss the cation exchange of fluorine yarn 11.
Particularly, by joining the cation exchange membrane with a thin layer of a different cylindrical molecular compound to M, the swelling of the 16 ion exchange Is membrane is suppressed and the fixed ion concentration is kept high and stable. It is presumed that the strength is further strengthened by the combination of molecular compounds and vinyl monomers.

In the present invention, a method for bonding a fine particulate polymer compound to a wood-based cation exchange membrane or a mirror material into which a cation exchange group can be easily introduced is specifically explained. Then, for example, by adhering, impregnating, etc., a vinyl compound in which a fine particulate polymer compound to be bonded to a water-containing cation exchange membrane or a membrane-like material that can easily conduct an ion exchange group is present, and the vinyl compound is There are methods such as polymerizing.

In the present invention, it is not preferable that the electrical resistance of the resulting composite cation exchange membrane increases by bonding a fine particulate polymer compound to the 1d ion exchange membrane of Miyafutsu elementary groups. Therefore, in general, the electrical resistance of the uninvented composite cation-exchange membrane must be kept to an extent that the fluorine-containing elementary group [2] before joining the polymer compound is 10 times, preferably 7 times, that of the ion-exchange membrane. be. From the point of view of the electrical resistance of this composite cation exchange membrane, the attached polymer compound 9 should be placed more on the surface layer than inside the fluorine-containing cation exchange membrane, and from the screen of the fluorine-containing cation exchange membrane. It is preferable to form it as thinly as possible on both sides. In addition, when the obtained composite cation exchange membrane is used as an electrolytic diaphragm, it is preferable to direct the thin layer containing the bonded polymer compound toward the cathode side rather than toward the anode side, where a thin film layer occurs. .

In the bonding method as described above, when a fine particulate polymer compound is dispersed in a single vinyl body and bonded to a cation exchange membrane of fluorine-containing thread or a membrane material into which cation exchange groups can be easily introduced, The film-like material is immersed in the dispersion, or the dispersion is applied to one or both sides of the film-like material.

After spraying to impregnate and adhere, polymerization is performed.

In addition, the vinyl monomer lid in the mixture of vinyl compounds in which a polymer compound is dispersed is effective when it is contained in a proportion of 1 to 90%, preferably 5 to 80%, based on the total amount of monomer compounds. The amount of the dispersed polymer compound varies depending on the particle size of the molecular cap, etc., so it cannot be definitively determined.
Good results are obtained when the NIL content is 0.5 to 50% of the total vinyl compound.

The dispersible polymer compound contained in the mixture of vinyl compounds described above exists in a thin layer in the surface saw part due to the relationship with the pores of the membrane to be joined.

The polymeric film-like material and beads having a fluorine atom and a cation exchange group or a functional group into which a cation exchange group can be easily introduced are not particularly limited and may be any conventionally known material used in the present invention. For example, a film made of a copolymer of tetrafluoroethylene and perfluoro(furkyl vinyl ether sulfonyl fluoride) such as perfluoro(3,6-thioxer-4-methyl-7-octensulfonyl fluoride), or These include hydrolyzed cation exchange membranes. In other words, the cation exchange membrane of fluorine-containing thread has 11 or more fluorine atoms in one direction that uniformly binds fluorine atoms and uniformly binds cation exchange groups or functional groups that can be easily introduced into the cation exchange groups. It is a film-like substance. The fluorine atoms in the polymer film may be partially bonded to the polymer chain, or may be perfluoro-based polymers (particularly to prevent polymer chain scission and
Most preferred is a perfluoro-based cation exchange membrane in which a fluorine atom is bonded to a position where an ion exchange group is stably bonded. As the cation exchange group, one or more conventionally known cation exchange groups are used, including a sulfonic acid group, a carboxylic acid group, a sulfuric acid ester group, a phosphoric acid group, a phosphorous acid group, a phosphoric acid ester group, and a phosphoric acid ester group. One or more selected from the group consisting of an acid ester group, a thiol group, a phenolic hydroxyl group, an acid 7-amide group bonded with a dissociated hydrogen atom, and a negatively charged metal chelate compound. It may also be a polymeric film-like material bonded with fluorine atoms having a functional group that can be easily converted into a cation exchange group (such functional groups include acid esters, acid anhydrides, acid halides, etc.). 2,
Furthermore, the above-mentioned cation exchange membrane may be manufactured by any conventionally known manufacturing method, including those having a co-M-bonding crosslinked structure, those insolubilized by hydrophobic bonds, and those having a simple polymer chain. It may be any material that is insolubilized by entanglement, and there is no restriction at all as long as it has fluorine atoms and cation exchange groups uniformly bonded. Furthermore, these cation exchange membranes of fluorine-containing threads were prepared by forming an acid amide with ammonia, forming an acid amide bond with a -class amine, forming an acid amide bond with a diamine or polyamine, and heating them at 170°C.
If the composite membrane of the present invention is manufactured using a cation exchange membrane that has been improved by treatment at a temperature at which the cation exchange membrane does not deteriorate, the performance of the modified R6 membrane can be further improved and High performance can also be stably maintained for a longer period of time.

Next, the fine particulate polymer compound to be bonded to the polymer membrane of the above-mentioned fluorine-containing thread cation exchange membrane is one that has the property of swelling with the vinyl monomer described later and has a molecular weight of 5.
If it is in the range of 0.000 to 5.000 million, it is a powdered polymer and a 9-branched polymer.

Any crosslinkable polymer may be used. For example, olefins such as ethylene, propylene, butene.

Epoxy compounds such as propylene oxide and ethylene oxide, vinyl monohalides such as vinyl chloride lJt', vinyl iodide, and vinyl butthoride 1. Vinylidene chloride, vinylidene fluoride, -ethylene chloride trifluoride, 4
Polyhalogenated vinyls such as fluorinated ethylene, styrene.

Aromatic vinyl compounds such as chlormenalstyrene, vinyltoluene, ethylvinylbenzene, divinylbenzene, trivinylbenzene.

a-ring vinyl compounds such as vinylpyridine and vinylpiperazine, vinyl ester compounds such as acrylic esters, vinyl acetate, methacrylic esters, styrene sulfonic esters and vinyl sulfonic esters, zutathiene, imprene, and chloroprene. , perfluorobutadiene, and other allyl compounds.

Allyl 7mine, allyl alcohol, 7lyl chloride, etc., perfluoro(alkyl vinyl ether), α-fluorostyrene, α, β.

β' −)! J Fluorostyrene, α-Fluo I:
17 acrylic acid esters, fluorine-containing vinyl monomers such as α, β, ly'-+・refluoroacrylic esters,
In addition, polymer compounds obtained by polymerizing or copolymerizing one or more monomers selected from 5), such as fluorinated carbon wool, may be suitably used.
100 microns, preferably 0.01 to 10 microns, preferably as small as light emission.Furthermore, a low molecular weight dispersant may be added to make the dispersion uniform and stable. In addition, although M and releasable ion exchange groups may be present in the 8 layers in which these polymer compounds are bonded, the number of ion exchange groups is smaller than that of the fluorine-containing cationic ion exchange membrane. On the other hand, the vinyl monoluteate used in the present invention swells the polymer compound bonded to the polymer U-shaped material as described above,
There is no particular restriction as long as it is polymerizable, but it is preferable that the polymer film-like material also swells. For example, monovinyl monomers include styrene, vinyltoluenes, methacrylates, acrylates, acrylonitrile, vinylpyridines, N-vinylpyro, lydones, vinylimidazoles, butadines, isoprenes, chloroprenes, and vinyl chloride. , vinyl acetate, acrolein, methyl vinyl ketone.

Chloropomethylstyrenes, monochlorostyrenes, polychlorostyrenes, α-fluorostyrene, α, β, β
1-Trifluorostyrene.

α-methylstyrene, vinylidene chloride, vinyl fluoride, hnylidene fluoride, chloromethylstyrenes, vinylsulfonic acid esters, styrenesulfonic acid esters rA
, 7! I esters of sulfonic acid, esters of vinyl phosphonic acid M, esters of styrene phosphonic acid.

Styrenephosphine E esters, vinylphosphinic acid esters, vinylphenolic acid esters,
Vinyl acetate, tetrafluoroethylene, trifluoroethylene, ethylvinylbenzenes, maleic esters, itaconic esters, vinyl bromide, and then as a crosslinking agent (polyvinyl compound), m-, P-, O - Divinylbenzene, divinylsulfone, butadiene, ri0pprene, isoprene, trivinylbenzenes, divinylnaphthalene, trivinylnaphthalene, diallylamine, triallylamine,
One or more types of divinylpyridines, divinylchlorobenzenes, polyacrylates of polyhydric alcohols, polymethacrylates, divinyl ether, divinylacetylene, divinyl sulfone, etc. are used. In addition, vinyl sulfonic acid and salts, styrene sulfonic acid and salts, allyl sulfonic acid and salts, vinyl phosphonic acid and salts, styrene phosphinic acid and salts, vinyl phosphinic acid and salts, acrylic acid, methacrylic acid, α-phenylacrylic acid , α-ethyl acrylic acid, α-halogenated acrylic acid, maleic acid.

Itaconic acid, α-butyl acrylic acid, vinylbenzoic acids, naphthalene rings with a vinyl group and a carboxyl group, etc., may also be used in an amount of 5% or less based on the total compound mixture. If a large amount of these is used in the vinyl monomer mixture, a large amount of cation exchange groups will be introduced into the polymer compound claw, resulting in significant swelling of the polymer compound layer, which is unfavorable for the performance of the composite membrane of the present invention. In the present invention, it is necessary to make one or more of these polyvinyl compounds and monovinyl compounds exist and then polymerize the vinyl compound to form a polymer in order to obtain a good composite membrane of the present invention. In order to form a polymer, a radical polymerization initiator, X-rays, radiation, i-son beams, electric discharge, light energy, etc. can be used. When using a radical polymerization initiator, any polymerization initiator that has a half-life of 10 hours or more at a temperature of 60° C. or higher can be used without any restriction. For example, benzoyl peroxide, α, αIy zoinptyronitrile, lauryl peroxide, 1ert-butylcumyl peroxide, cumene hydroperoxide.

Tert-butyl-lauryl peroxide is one of them, and is appropriately selected depending on the type of polymer compound used here and the treatment method. When a fine particulate polymer compound is layered and at the same time a vinyl compound is made to coexist and heated to above the softening point, after the M9 particulate polymer compound is attached, vinyl 7/mer is made to coexist and heated to above the softening point. In some cases, good results are obtained when using an initiator that decomposes at a temperature above the softening point of the polymer compound. If the softening point of a polymer compound that can be easily converted into a membrane is extremely high, depolymerization will occur if a vinyl compound is allowed to coexist with the polymer compound and heat-treated to the softening point. In such a case, it is effective to preliminarily attach a polymer compound to +J and heat it to its softening point, and then attach and infiltrate the vinyl compound for polymerization. In this case, as a method for polymerizing the vinyl compound, it is also effective to use a radical initiator;

Polymerization may also be carried out by electric discharge or the like. For example, when using radiation, polymer compounds with fluorine atoms bonded to them are generally degradable polymers, so polymerization conditions such as preventing the decomposition of these polymers and preferably forming a crosslinked structure, and Needless to say, the type and composition should be selected.

In addition, in order to stably attach a cation exchange membrane or a polymer compound that can be easily converted into a cation exchange membrane and a fine particulate polymer compound, it is necessary to use not only vinyl compounds but also epoxy compounds and amines. It is also good to use a compound with ion exchange properties. For example, polytetrafluoroethylene is dispersed in fine particles of NN'dimethylformamide, and this is applied uniformly to a perfluoro (furkyl vinyl ether sulfonic acid) film, the solution is adhered to the film surface, and the film is air-dried. is heated at around 200°C, and further impregnated with acrylic acid esters and irradiated with gamma rays to polymerize, forming a crosslinked structure in the polymer compound of the layer, and also forming a cation exchange membrane. An example of this is a method in which an ester of acrylic acid is bonded within the molecule.

The content of the present invention is not limited by the following examples. In the examples, unless otherwise specified, the electrolysis of alkali metal salts was carried out using a two-chamber electrolysis system with a current-carrying membrane area of 0.5 dm'', and the anode was a titanium wire mesh coated with titanium oxide and ruthenium oxide. An iron wire mesh was used as the cathode.A saturated alkali halide aqueous solution was constantly flowed into the anode chamber, and water was constantly added to the cathode chamber so that the alkali hydroxide obtained was 6N. The gap between the anode and cathode was 3 gm, and the membrane was supported on the anode.The electrolysis temperature was 60 to 90°C, and the current density was 3 gm.
It was 0A/am'. In addition, the electrical resistance of the membrane! 6.0
Measurements were made in N-NaOH at 80° C. using 1000 cycles of alternating current.

Further, the amount of alkali halide in the obtained alkali hydroxide was determined by the colorimetric method of JIS K-1200.

Example 1 Perfluorosulfonic acid fluoride obtained by hydrolyzing a polymer compound obtained by copolymerizing tetrafluoroethylene and perfluoro(3,6-thioxer-4-methyl-7-octensulfonyl fluoride) 1200 million ton exchange membrane
After air-drying the product having a weight equivalent Jt (exchange volume: i0.833 milliequivalent/11 dry membranes) and a thickness of 0.15 decoys, it was subjected to the following treatment. That is, 5 parts of divinylbenzene (approx. 5 parts purity)
5+yo)+5 parts of styrene.

methacrylic 112.5g, 4-vinylpyridine 2.5g
A base resin made of polyvinyl chloride (manufactured by Sumitomo Chemical Co., Ltd.) is added to a monomer mixture containing 0.3 parts of tert-butyl lauryl peroxide.

After adding 1 part of PX-A) and uniformly dispersing it, this was applied uniformly to one side of the above cation exchange membrane, and 110
Polymerization was carried out by heating at ℃. In this case, the polyvinyl chloride powder was swollen by the monomer mixture and reached a softening point or higher, and was stably fixed to the cation exchange membrane. The resulting composite membrane was immersed in 6.0N NaOH to make it Na-type, and then its electrical resistance was measured and found to be 2.8r.

Next, when electrolysis of saturated saline was carried out using this composite film, 6.0N-NaOH was obtained and the current efficiency was 93.
%Met. Furthermore, tli was carried out under the same conditions for 3 consecutive months.
When the solution was implemented, the current efficiency was 92% after 3 months. On the other hand, the electrical resistance of the cation exchange membrane not subjected to the above treatment was 2.5 Ω-d, and the current efficiency was 68% when electrolyzed under the same conditions as above.

Comparative Example 1 5 parts of styrene is added to the perfluor-10 alkyl vinyl ether type cation exchange hh of Example i+l11.

5 parts divinylbenzene, 2.51 SIl methacrylic acid
A monomer mixture containing 2.5 parts of 4-vinylpyridine and 0.3 parts of 1ert-butyl lauryl peroxide (not containing polyvinyl chloride) was uniformly applied in the same manner as in Example 1 and polymerized by heating. . After the composite cation exchange membrane obtained here was immersed in 6.0N-NaOH to form the Na type, the electrical resistance was measured to be 3.0Ω-d, and the same as in Example 1 was obtained using saturated saline solution. When electrolysis was carried out, the current efficiency was 93% initially, but after 3 months, the current efficiency was 83%.

Example 2 A copolymer of tetrafluoroethylene and perfluoro(3,6-thioxer-4-methyl-7-, t-ctenesulfonyl fluoride) was used to obtain 1100 weight equivalent f (exchange volume fIk).
O, 91 mil J current view/9 dry film) thickness Q, l mr
Same as sheet a, 1500 weight tray (exchange capacity 0.
67#! Using a tensile membrane obtained by sandwiching tetrafluoroethylene (1) between two 0.05-thick sheets of 0.05 g dry film), each film was Diethylenetriamine was added to the lower side of the membrane and allowed to stand at room temperature for 1 hour to permeate the inside of the membrane to some extent to form sulfonamide bonds, after which it was lightly washed with water and heated at 200°C for 3 hours.

This membrane surface/# part has an acid 7 amide bond and part 1 (inner part 5 parts styrene in a polymer membrane having an ion-exchangeable group,
5 parts of divinylbenzene with a purity of 55%, 5 parts of acrylic acid,
tert-butyl lauryl peroxide (trade name: Verbutyl L) in 5 parts of 2-methyl-5-vinylpyridine.

0.4 parts of Nippon Oil & Fats Co., Ltd.) were added, 1 part of polyethylene powder (trade name: Frozen) was added, and 0.4 parts of styrene-tadiene copolymer rubber was added to improve dispersibility.
．． A mixed solution of 5 parts was applied uniformly. Note that this coating is on the side of the composite polymer membrane on which acid amide bonds with low exchange capacity are formed. Next, the surface of this polymer membrane was covered with a polyvinyl alcohol sheet and heat-treated at 120° C. for 16 hours. The electrical resistance of the composite membrane obtained by the treatment of the present invention is 2.6 Ω-d, and the current efficiency is 94 when 7.0N-NaOH is obtained by electrolyzing saturated saline.
%Met. In addition, when electrolysis was continued under the same conditions, 3
Obtained 7.0N-NaOH even after several months and current efficiency was 94%.
Example 3: Copolymerization of tetrafluoroethylene and perfluoro(3,6-thioxa-4-methyl-7-octensulfonyl fluoride).
91 mi! Between two sheets with a thickness of 0.05 m and a weight change of <1500 (exchange capacity 0.67 mm! J equivalent/9 dry membrane), which is the same as a sheet with a thickness of 0.1 dragon (J equivalent / g dry membrane) ,
A polymer membrane obtained by fusing a tetrafluoroethylene cloth was immersed in 6.0N-NaOH and hydrolyzed to obtain a composite ion exchange membrane. Using this cation exchange membrane as an acid house, the composition shown in Table 1, Section 1-0, was uniformly coated on the membrane surface with lower exchange capacity, and then heated and polymerized at 110°C to form a coating. A membrane was obtained. The carbon fluoride in the above composition was sufficiently stirred to be uniformly dispersed before being applied.

The resulting composite membrane was then heated to 60°C in 6. ON-NaO
After being immersed in H to form NaW, it was subjected to on-site electrolysis using a two-base method. The results are shown in Table 1. Example 4 Hydrolysis of a polymer film obtained from a copolymer of tetrafluoroethylene and Verfluorop (3,6-thioxer-4-methyl-7-octensulfonyl fluoride) do,
A cation exchange membrane with an exchange capacity of 0.83 milliequivalents/9 dry membranes was obtained. After converting this cation exchange membrane into a hydrogen ion type and drying it under reduced pressure, a solution prepared by uniformly dispersing 1 part of fine carbon powder in 10 parts of methanol was quickly applied to one side in a uniform thin layer, and the pressure was reduced again. After drying, a uniform layer of fine carbon fluoride powder was formed on the surface of the perfluorinated cation exchange membrane.

Next, this film was sandwiched between two aluminum plates with a gap of 3 mm, and the side with the fine carbon fluoride powder adhering to it faced up.
A 60-cycle alternating current of 00V was applied, and tetrafluoroethylene and trifluoromonochloroethylene gases were introduced onto the membrane surface to which carbon fluoride was attached. That is,
Helium gas was introduced into tetrafluoroethylene cooled with liquid nitrogen, and tetrafluoroethylene was introduced using helium as a carrier gas. In addition, trifluoromonochloroethylene was cooled with dry ice and methanol, and helium gas was introduced as a carrier gas to send trifluoromonochlorethylene onto the membrane surface.These seven polymers were polymerized by electric discharge. , -11 (carbon fluoride was deposited on the membrane surface while penetrating into the surface layer of the membrane. The weight increase of the membrane due to this discharge polymerization was 5.6% for tetrafluoroethylene and 5.6% for trifluoromonochloroethylene. It was 1.8%.

The obtained Enoki composite film was immersed in 6.0N NaOH at 60°C to make it into Na type, and then used for electrolysis of saturated saline by a two-base method according to a conventional method.

Several membranes prepared by discharge polymerizing tetrafluoroethylene had an electrical resistance of 2.5 Ω-Cml, but 6.5 N-
The concentration of NaOH obtained was 90%. I did this for 3 consecutive months, but after 3 months I still had 0.
5N NaOH was obtained and the current efficiency was 90%.

In addition, a composite film made by polymerizing trifluoromonochloroethylene by releasing N has a value of 6.5 N = Na OH,
The current efficiency was 95%. 3 months he is 6.5N-N
AOH was obtained and the current efficiency was 94%. Note that the electrical resistance of this film was 2.3 Ω-d.

When an ion exchange membrane without any surface treatment was used under the same conditions, 6.5N-NaOH was obtained and the current efficiency was 70%, but after 3 months it was 65%. . The negative resistance of this film was 2.2Ω-d.
In addition, in the above-mentioned remission, the surface-treated membrane was subjected to the treatment with the treated surface facing the cathode.

patent applicant Tokuyama Soda Co., Ltd.

Claims (1)

[Claims] An abrasive granular polymer compound and a vinyl monomer are present on the surface of a high-quality polymer containing a fluorine atom and a cation exchange group or a functional group into which a cation exchange group can be easily introduced in post-treatment. A method for producing grade 9 plates, characterized in that the vinyl M ii'c K is polymerized and an ion exchange group is introduced as necessary.