JPS604537A - Production of anion exchange membrane - Google Patents

Abstract

PURPOSE:To obtain an anion exchange membrane having excellent electrochemical properties, by impregnating a compound containing both a polymerizable group and a group capable of forming a quaternary ammonium group to a non-crosslinked anion exchange membrane having specific main chain, polymerizing the compound, and converting the above group to quaternary ammonium group. CONSTITUTION:The objective anion exchange membrane is produced by impregnating (A) a compound having both a polymerizable group and a group containing quaternary ammonium group of formula II, III or IV (R1, R2 and R3 are lower alkyl; Z is halogen anion, BF<4->, SbCl6<->, etc.; R6 is H or lower alkyl; a is 2-4) in (B) a noncrosslinked anion exchange membrane having perfluorocarbon polymer as a main chain and composed of the recurring unit of formula I (X is F or CF3; Z is a group containing quaternary ammonium group; l is 0 or 1-5; m is 0 or 1; n is 1-5; p/q is 4-16), optionally in the presence of a solvent and a radical polymerization initiator (e.g. benzoyl peroxide), polymerizing the compound, and converting the above group to quaternary ammonium group.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for improving the electrochemical properties of a non-crosslinked anion exchange membrane whose main chain is composed of a perfluorocarbon polymer.

More specifically, a non-crosslinked anion exchange membrane whose main chain is a perfluorocarbon polymer is impregnated with a compound having both a group capable of becoming a quaternary ammonium group and a polymerizable group, and then polymerized. The present invention provides an anion exchange membrane with excellent electrochemical properties, which is obtained by converting the polymer into a quaternary ammonium group.

Several of the present inventors have already filed applications for novel anion exchange membranes whose main chain is composed of perfluorocarbon polymers. Compared to conventionally known and used hydrocarbon-based anion exchange membranes, the obtained anion exchange membrane has the following characteristics: ■ It is stable against repeated drying and wetting, and ■ It is not prone to embedding. *Excellent heat resistance and solvent resistance, etc.
Various excellent patents have been discovered.

In general, fluorine monomers that have a functional group that can be converted into a carboxylic acid group (e.g., an ester group) or a functional group that can be converted into a sulfonic acid group (e.g., a sulfonyl fluoride group) have poor polymerizability and are not included in copolymers. It is not possible to introduce more than a certain amount (approximately 1.0 to 1.5 meυ meυ) of the above-mentioned functional groups into the material.

Therefore, when an anion exchange membrane is synthesized using a membrane obtained from such a copolymer as a raw material, the amount of cross-polymerization of the resulting membrane cannot exceed the above-mentioned value. As a result, it is difficult to reduce the electrical resistance of the membrane, which is not favorable for economy 11].

Therefore, the authors of this @I'JJ have continued to study intensively to improve this point, and as a result, they have found that the main chain can be a quaternary ammonium group in a non-crosslinked anion exchange membrane made of a perfluorocarbon polymer. It was discovered that an anion exchange membrane with excellent electrical resistance can be obtained by impregnating a compound having both a group and a polymerizable group, followed by polymerization and converting the 1y compound into a quaternary ammonium group. The present invention has been achieved.

Examples of anion exchange membranes that can be used in the present invention include copolymer membranes comprising repeating units represented by the following general formula.

small OF.

However, '+' and n can take different numbers for each pendant chain even in the same main chain.Furthermore, the value of p/q means the average value in the copolymer, and in each repeating unit. Naturally, this includes cases where different values are taken.

in particular, 1 F2 C.F.

Hs F2 0, CH.

■ F2 It is a hat.

The thickness of the copolymer membrane used in the present invention is in the range of 1.mu.m to 500 .mu.m.

On the other hand, it can be used in the form of a flat film or a cheap shape.

Combine the above fluorine-based anion exchange with 9 impregnations.

Compounds that can be converted into quaternary ammonium groups include 4
- Vinylpyridine derivatives such as vinylpyridine and 6-vinylpyridine, alkylaminostyrene derivatives such as dimethylaminostyrene and diethylaminostyrene, halomethylstyrene derivatives such as chloromethylstyrene and bromomethylstyrene, and dienes such as butadiene-1-pyridine. Derivatives, vinylimidazole, etc. can be used.

Of course, if the obtained polymer is soluble in water or an aqueous bath medium, divinylbenzene or butadiene may be used to carry out a crosslinking reaction during polymerization.

In the method of impregnating the anion exchange membrane with the above-mentioned compound, it is possible to directly impregnate the compound, or if the compound is in a solid state or the impregnation rate is slow, an appropriate solvent may be used. can.

For polymerization, a radical initiator such as benzoyl peroxide or azobisisobutyronitrile is simultaneously present in the film during impregnation, and radical polymerization can be carried out by heating or the like. Furthermore, if necessary, polymerization can be carried out using radiation, X-rays, or ultraviolet rays.

When converting to a quaternary ammonium group after polymerization, the following method may be adopted.

1. If the group contains a nitrogen atom that can be converted into a quaternary ammonium group, it can be converted to a quaternary ammonium group by treatment with an alkyl halide such as methyl iodide or short propane according to a conventional method.

Z If a halogen atom is included as a group that can be converted into a quaternary ammonium group, it can be converted to a quaternary ammonium group by treatment with an amine containing a tertiary amino group such as trimethylamine or triethylamine according to a conventional method. .

The anion exchange membrane of the present invention can of course be used in conventionally known techniques such as diffusion dialysis, JE gas dialysis, and diaphragms for organic electrolytic reactions. Because it is made up of
This membrane can be used satisfactorily in systems where oxidizing agents are generated, systems that require high temperatures, etc.

Next, the present invention will be explained in more detail with reference to Examples. In the following examples, the membrane resistance was determined by fully equilibrating with 0.5N saline and then immersing the membrane in a 05N saline bath solution.
? The measurements were taken at a cycle temperature of 25°C. Also, 1 efficiency of the membrane is 0.5N saline bath solution and 2. ON*Calculated using the Nernst equation from the membrane potential generated between the salt water bath liquids,
This is what I did.

Example 1 CF2=CF2 and CF,=CFOOF20FOOF20
F2SO, FC'l! I.

Copolymer film obtained by co-merging with DuPont Nafion 114 (trade name), jl@thickness 100
μ, sulfonic acid conversion JI exchange rate o, 91 mm +'li
：／ ? - Dry film] was treated with 2N hydrochloric acid, converted to sulfonyl chloride, then treated with hydrogen iodide, and washed with alkali to form a sodium carboxylate salt.

The structure of the pendant chains of this membranous copolymer is -QC! F
20FOCF2CO2Na. This membrane was coated with 8N salt C.
F.

Hydrolysis by treatment with clarification/methanol (volume ratio 1:1),
After esterification, the mixture was heated at 120° C. for 24 hours in phosphorus pentachloride/phosphorus oxychloride (weight ratio 1:1.6). Thereafter, it was washed in a 4J tray carbon solution and then dried. The obtained film has an infrared absorption spectrum of 1800 cm-'
shows strong carbonyl absorption.

One mole of the obtained solution was immersed in dry diethyl ether, and dimethylamine gas (1.3 molar concentration) was passed therethrough while cooling with water to react for 6 hours at room temperature at 18:1F. Mix 6% sodium bicarbonate with methanol (volume ratio 1:1) at 80°C.
After washing for 5 hours and drying under reduced pressure overnight, a colorless and transparent amide 4]~(terminated sweetfish-6NMe2) was obtained.
) IN was obtained.

Sodium borohydride was dissolved (0.53 molar concentration) in dry diethylene glycol dimethyl ether under an argon atmosphere, and then the monomer obtained in Example 1 was immersed. A dry diethylene glycol dimethyl ether bath solution of boron trifluoride ether complex (α62 equivalent to sodium borohydride) was added dropwise to the solution while cooling with water. By reacting for 5 hours under cooling and further at 100°C for 18 hours, 1 700 C11- in the infrared absorption spectrum was obtained.
The absorption of 1 disappears and the amine type (terminal group -CH2NMe2
) Reduction to the membrane had completely progressed.

The obtained membrane was washed with methanol and further dried to obtain an amine type J sample. This membrane was placed in a methanol bath of methyl iodide (volume ratio 1:4) and reacted at 60° C. for 48 hours. After washing the obtained membrane with methanol, it was dissolved in a methanol solution of lithium chloride (1.28 mol σ, ゛ti) for 60 min.
The reaction was carried out at ℃ for 24 hours.

This was heated to 60° C. in 1 plJ 7 methanol to obtain the desired ammonium chloride type film.

In the staining test, the obtained membrane was not stained with crystal violet, but was colored red with bromocresol purple (blue-purple in basic water), yellow-orange with cresol red (red-purple in basic water), and anion exchange (appearance). The existence of the group was confirmed.

In addition, the exchange capacity of this anion exchange 1ph is 0.82 milliequivalent/2 dry membrane, and the electrical resistance is 66 Ω cm.

The transport number was α87.

After immersing the sample at 25°C for 24 hours in an impregnating bath solution consisting of 80 parts of chloromethylstyrene, 20 parts of divinylbenzene (purity 55%), 2 parts of benzoyl chloride, and 20 parts of methanol, the sample was taken out and removed. glass plate.

The mixture was sandwiched between a chloroprene rubber and a polyester sheet and polymerized by heating at a temperature of 75°C to 80°C for 16 hours under a nitrogen stream. Next, the mixture was reacted for 10 hours in an amination bath consisting of 10 parts of trimethylamine (50%) and 6 parts of methanol to convert it into quaternary ammonium chloride with chloromethyl groups in the membrane.

The electrical resistance of the obtained anion exchange membrane was 2.1Ω・cm”
.

The transport number was 0.88.

Example 2 IIQ similar to that used in Flu Example 1 was mixed with dimethylaminostyrene ao part, divinylbenzene (purity 55%) 2
0 parts, benzoyl peroxide, and 20 parts of methanol at 25°C. (After immersion, the sample was taken out, placed between a glass plate, chloroprene rubber, and a polyester sheet, and heated and polymerized at a temperature of 75°C to 80°C under a nitrogen stream for 16 hours.

Next, in a bath of 10 parts of methyl iodide and 3 parts of methanol, 10
Soaking for an hour converted the dimethylamine groups to quaternary 77monium iodide.

The electrical resistance of the obtained anion exchange membrane was 2.0Ω・cm2
The transport index was 0.89.

Example 5 C! F2=C! F2 and OF, -CFOCF, CFO
C! Tl'20F2Co20H3CF.

Co-11 obtained by copolymerization with
j film thickness 110 μ, C02I (conversion) Okuyoshi 1.4 mEq/2 dry film), hydrolysis angle γ (-/ko.2
NHOz treatment was performed to carboxylate Ija.

Using the thus obtained iJ'4 and dimethylamine, an anion paternal conversion box having a quaternary ammonium chloride group of 1'' was obtained in the same manner as in Example 1.

The electrical resistance of the film is 60ΩC1l+2. The transport index is 0.84.

The sample J was treated in the same manner as in Example 19-1. +-1
The electrical resistance of the film was 1.8Ω·cm2. The dissolution rate is 087
Met.

Seed B [Example 4 The same carvone rlRI plant as used in Example 1 was treated with phosphorus in the same manner. b) The prepared membrane was immersed in a dry ether bath solution of N-methylpiperazine (1.0 mole strength) and left at room temperature for 64 hours. Vacuum drying (50℃)
After that, it is advantageous to use a slightly brown J color, which is less stained than crystal violet and has a 180
1 absorption at 0 cm-1 disappears and a new absorption at 1690 cm-1
'A strong absorption thought to be derived from the carbonyl of the carboxylic acid amide was observed.

The resulting membrane was then immersed in a dry digram bath solution of sodium borohydride (0.5 molar concentration) and diluted with boron trifluoride ether analogue (0.5 molar concentration relative to sodium borohydride) under an argon atmosphere while cooling on ice. Dry diglyme bath solution of No. 62) was added dropwise. The reduction proceeded completely by reacting under cooling for 5 hours and then at 100° C. for 18 hours.

After washing the obtained diamine film with methanol, it was treated with methyl iodide in methanol at 60° C. for 2 days. After washing with methanol, the mixture was reacted in a methanol solution of lithium chloride at 60° C. for 2 days, and heated and washed again with methanol to obtain the desired anion exchange membrane having quaternary ammonium chloride groups.

The electrical resistance of loading and unloading is 9Ω・cm2. The transport index is 0.84.

aiIs? 80 parts of 4-vinylpyridine, 20 parts of divinylbenzene, 10 parts of styrene, 2 parts of peroxybenzoyl
and 24 parts of methanol at 25°C.
After soaking for an hour, take it out and remove it from the glass plate.

The mixture was sandwiched between a chloroprene rubber and a polyester sheet and polymerized by heating at a temperature of 75°C to 80°C for 16 hours under a nitrogen stream.

Next, in a bath of 10 parts of methyl iodide and 6 parts of methanol, 10
After being soaked directly for a period of time, the methane k''N in the pyridine ring was converted into quaternary ammonium iodine.

The electrical resistance of the obtained rut film is 2.8Ω・cm2.・Transportation number is [
It was L88.

Example 5 #'lfi ((L8 mo#/A degree) K,'
A methyl ester membrane similar to that used in flifl was immersed and allowed to react at room temperature for 200 hours. After drying with ether v'aΦ, a colorless film was obtained by drying under reduced pressure, and the infrared absorption spectrum odor was C!
-J(.

Carbonyl absorption was observed at 1700 cm-1. This membrane was stained with crystal violet and the same procedures as in Example 4 (reduction, alkylation,
By performing counter ion exchange), an anion exchange membrane having quaternary ammonium chloride groups was obtained.

The electrical resistance is 5.5Ω・Cm2. The transport number was a86. The sample was treated in the same manner as in Example 4 to obtain an ion exchange membrane. The electrical resistance of the obtained anion exchange membrane was 2.9 Ωmcm2. The transfer number was 0.89.

Example 6 0F2=C! F2 and C! F2=OFOCjF2C! F
Copolymer film obtained from copolymerization with OCF and CF25O2FCF3 (film thickness 10
0μ, So, H conversion exchange capacity 09 milliequivalent/2 ・
Dry film) Shibuko.

The resulting sulfonyl fluoride membrane was heated with N in dry ether.
, N, N'-)rimetherethylenediamine (α8 molar concentration) overnight at room temperature and further at 50° C. for 5 hours.

Then, after washing with methanol, it was placed in saturated heavy water at 50°C.
It was treated for 8 hours. Thereafter, it was washed with warm water and dried. The resulting sulfonamide was reacted with methyl iodide in methanol at 50° C. for 48 hours. Thereafter, it was washed in methanol and treated with 1 volume of lithium chloride in methanol for 24 hours. Further, it was washed in methanol at 50°C for 8 hours.

The electrical resistance during loading and unloading was 5.20·Cm"r, and the M'ftW ratio was 0.86.

The loading and unloading process was carried out in the same manner as in Example 4 to obtain an anion exchange membrane. The electrical resistance of the obtained anion exchange membrane was 2.5Ωe
cm' l transport index is 0.89 te tv ivy.

Claims (1)

[Claims] ]) A non-crosslinked anion exchange membrane whose main chain is a perfluorocarbon polymer is impregnated with a compound having both a group capable of becoming a quaternary ammonium group and a polymerizable property, and then heated to a certain degree. Then, the anion exchange membrane to be used is composed of repeating units represented by the following general formula (% formula %). Claim 1
The method described in section. 3) The method according to claim 11, item 1 or 2, wherein the group containing a quaternary ammonium group is represented by the following general formula. 4) The method according to claim 1 or 2, wherein the group containing a quaternary ammonium group is represented by the following general formula. 5) The method according to claim 1 or 2, wherein the group containing a quaternary ammonium group is represented by the following general formula %.