JPS61133211A - Production of fluorine-containing ion exchange resin having crosslinked structure - Google Patents

Abstract

PURPOSE:To obtain the titled resin with high heat and corrosion resistance and good dimensional stability, by copolymerization, in the presence of a fluorine-containing nitrogen compound derived from specific reaction, between a fluorine-containing divinyl compound and fluorine-containing vinylcompound having specific functional group. CONSTITUTION:The objective ion exchange resin can be obtained by copolymerization (e.g., solution polymerization) at 0-ca.200 deg.C in an inert gas, in the presence of, as an initiator, a fluorine-contg, nitrogen compound (e.g., of formula I) derived from reaction of N2LF4 with polyfluoroacetylene com pound, between (A) a fluorine-contg.divinyl compound (e.g., of formula II) and (B) a fluorine-contg. vinyl compound having such functional group as to be convertible to ion exchange group by reaction [e.g., of formula III (X is Cl, F, OH)]. Used for gaskets, spacers, covering materials, etc.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fluorine-containing divinyl compound and a fluorine-containing divinyl compound.
This invention relates to a method for producing a fluorine-containing resin by copolymerization with a vinyl compound. More specifically, the present invention is directed to a process in which a fluorine-containing divinyl compound and a fluorine-containing vinyl 7mer having a functional group that can be converted into an ion exchange group by reaction are used in the presence of an initiator whose main components are a fluorine-containing nitrogen compound. The present invention relates to a method for producing a membrane-like resin having an ion exchange group and having a crosslinked structure, which is particularly useful as a diaphragm for dissolving food #1ilE, by copolymerizing the present invention.

[Prior art]

As a fluorine-containing copolymer having a functional group that can be converted into an ion exchange group by reaction, CF2=cFCOcF2CFY)nOCFRfCF is described in Japanese Patent Publication No. 7949/1983.
2So2F (Rf is fluorine or a perfluoroalkyl group having 1 to 10 carbon atoms, Y is fluorine or a trifluoromethyl group, and n is an integer from 1 to 3) and tetrafluoroethylene, etc. Copolymers are described. Furthermore, in Japanese Patent Publication No. 45-26303, CF2=CFO (CF28-X (however, n in the formula
is an integer from 2 to 12, and X is a group -CN, -COF,
-COOH, -COOR1) -COOM and -〇〇NR
2R3, R1 has 1 to 10 carbon atoms + R2
and R3 is one of R1 and M is sodium, potassium or cesium) and an ethylene-based monomer 2, such as tetrafluoroethylene, is described. The copolymerization of perfluorovinylsulfonyl fluoride or per7/I/orovinylcarboxylic acid ester and tetrafluoroethylene as described above is
Since the tetra7/I/oleethylene is a gaseous monomer with a boiling point of -76°C, the polymerization is generally carried out under high pressure in the presence of a radical initiator. In addition, in such copolymerization, a stable resin with high ion exchange capacity cannot be obtained unless the molecular weight of the resulting copolymer is increased. In order to maintain the solubility of
It is necessary to take measures such as stopping it at the stage of 0% or less. Therefore, a step of recovering and purifying the unreacted supernatant is required after polymerization. Furthermore, when producing an ion exchange membrane from a fluoropolymer, the copolymer must be sufficiently washed with a solvent and then extruded into a film at a high temperature of 200°C to 250°C. As mentioned above, the production of fluorine-containing thread polymers involves complicated polymerization operations, and the production of ion exchange membranes from the fluorine-containing thread polymers involves two steps of polymerization and molding, which requires a large amount of equipment and operations.

On the other hand, when a copolymer of perfluorovinyl sulfonyl fluoride or perfluorovinyl carboxylic acid ester and tetrafluoroethylene is introduced with a sulfone functional group or a carboxylic acid group after extrusion molding, the copolymer becomes polyetrafluoroethylene. Since this is a pseudo-crosslinking method that utilizes the crystallinity of ethylene, if the ion exchange capacity is large (that is, the proportion of monomers that can be converted into ion exchange groups in the copolymer is large), it is possible to use alkali in pure water.

It often swells significantly in aqueous solutions of acids and salts, methanol, acetone, chlorinated solvents, and fluorinated solvents, and eventually dissolves.

Therefore, for a fluorine-containing copolymer having a large ion exchange capacity, it is desired that the copolymer be crosslinked by covalent bonds rather than pseudo-crosslinking.

[Problem that the invention seeks to solve]

Fluorine-containing OF2. having a crosslinked structure due to covalent bonds. Methods of polymerization in the presence of azobisisobutyronitrile, benzoyl peroxide, etc. are known, but usually only oil or rubber-like polymers with low molecular weight are obtained, and radiation is used at ultra-high pressure. It is known that a polymer having a crosslinked structure can be obtained when this is done. In addition, attempts have been made to crosslink polymers by irradiating homopolymers or copolymers of perfluorovinyl compounds with radiation, but this approach results in uniform performance because the polymer collapses at the same time due to radiation irradiation. It is difficult to convert the koji into koji, and it is not considered to be an industrially superior method. Furthermore, Japanese Patent Publication No. 44-15425 describes a method for producing a thermosetting resin by polymerizing a compound of the formula CF2=CFO(CF2CF20)2~2゜CF=CF2 with various polymerization initiators, or Japanese Patent Publication No. 44-32051.
In the publication, the formula CF2=CFOCnF2nOCF=CF
2 (where n = 2 to 24), or a mixture of this compound and a perfluoroalkyl vinyl ether, is polymerized using a polymerization initiator capable of generating perfluorinated free radicals at the polymerization temperature. A method for making addition polymers is described. However, the preferred polymerization example described in these patent publications is perfluorodivinyl ether homopolymerization, and 3CF2=CF
Copolymerization with perfluoroalkyl vinyl ethers such as OC3F6 has only been suggested.

In contrast, the present invention relates to the copolymerization of a fluorine-containing divinyl compound and a fluorine-containing vinyl compound that can be converted into an ion exchange group by reaction, and is directed to the production of a fluorine-containing resin having a crosslinked structure and an ion exchange group. This is the purpose.

It is generally known that even the presence of a very small amount of diethylene glycol dimethyl ether or methylene fluoride, which are hydrocarbon compounds used when synthesizing hahafluorodivinyl ether, has the effect of inhibiting radical polymerization. On the other hand, perfluorovinylcarboxylic acid ester or perfluorovinyl sulfonic acid ester, which is a fluorinated vinyl hexamer that can be converted into an ion exchange group, used in the present invention is an alcohol consisting of a hydrocarbon and a perfluorocarbon dispersion. Since it is an ester of sulfonic acid, it was thought that polymerization would be similarly difficult even if it was polymerized using a polymerization initiator that generates free radicals at the polymerization temperature.

[Means to solve the problem]

In view of the above, the present inventors conducted intensive research on copolymerization of a fluorine-containing divinyl compound and a fluorine-containing vinyl compound that can be converted into an ion exchange group by reaction, and found that N2F4 was reacted with a polyfluoroacetylene compound as a polymerization initiator. The present inventors have discovered that a fluorine-containing resin having a good crosslinked structure and an ion exchange group can be obtained by using a fluorine-containing nitrogen compound obtained by the above method, and have thus come to provide the present invention.

In the present invention, an ion exchange membrane made of a fluorine-containing resin having a particularly crosslinked structure, little dimensional change, and a large ion exchange capacity can be produced by a heavy polymerization operation and polymerization and molding operations such as poetic polymerization in one step. In order to obtain it easily, it is essential to use a monomer mixture of a fluorine-containing divinyl compound and a fluorine-containing vinyl compound having a functional group that can be converted into an ion exchange group by reaction. However,
A fluorine-containing ion-exchange resin having the desired crosslinked structure is obtained by copolymerizing a mixture of such a fluorine-containing divinyl compound and a fluorine-containing vinyl compound having a functional group that can be converted into an ion exchange group by reaction. Therefore, it is preferable to achieve as high a polymerization rate as possible. In order to efficiently obtain a fluorine-containing ion exchange resin having a desired exchange capacity, a predetermined amount of a fluorine-containing vinyl compound having a functional group that can be converted into an ion exchange group by a reaction with a fluorine-containing divinyl compound is required. is preferably polymerized at a high rate. Therefore, in the present invention, it is extremely effective to use a compound obtained by reacting Per7A/oacetylene with N2F4 as a polymerization initiator. Incidentally, benzoyl peroxide, lauroyl peroxide, , diacyl peroxide such as imbutyryl peroxide, hydroperoxide such as cumene hydroperoxide, t-butyl hydroperoxide, and dicumyl peroxide.

Dialkyl peroxide such as di-t-butyl peroxide, t-butylperoxyneodecanoate, t-
Furkyl perester such as butyl peroxybiplate, percarbonate such as bis(4-t-butylcyclohexyl) peroxydicarbonate, diisopropyl peroxydicarbonate, azobisisobutyronitrile, azobiscyclohexanecarbonitrile, etc. azo initiators, succinic acid peroxide, dipentafluoropropionyl peroxide, ditetrafluorobrobionyl peroxide.

Di(trichlorooctaf/I/ophexanoyl) peroxide, di(tetrachloroundecafluorooctanoyl) peroxide, Shiba-fluoro-2-IIL
-Propooxypumapuonyl peroxide + NF'
3e N2F 4s N2 F2+potassium persulfate,
When copolymerization was attempted using an initiator such as ammonium persulfate + COF 3 +IF, ) ethylaluminum, diisobutylaluminum hydride, or diethylaluminum chloride, or ultraviolet light, an oily low-1 compound was obtained in a few cases. However, the expected three-dimensionally crosslinked polymer could not be obtained. The present invention will be explained in further detail below.

The fluorine-containing divinyl compound constituting the fluorine-containing crosslinked polymer of the present invention is CF2=CF0(CF2)2~
1o(02'FCF2), ~30CF=CF21.

In addition, a fluorine-containing vinyl monomer having a functional group that can be converted into an ion exchange group by reaction is CF2 (X is 3CA't
F+ OH+ ocu8. OC2H5,ONa+OK
, NH2, -NHCH2CH2NH2, -NHCJ(2
CH2N” (CH3)3 (a type of J-) 3CF
2=CF3 CFO (OF2 FO). , 3(CF2)1-5Y.

CF, = CFO (CF2 redundancy 0). , 3 (CF 2CF
20) CF2Y (Y is -CN, -COF, -C
OOH, -COOR,.

-〇 〇 0M and -CONR, R1, where R1 has a carbon number of 1 to 10. Preferably 1 to 3 alkyl groups, each R2 and R3 being hydrogen or one of R1, and M being sodium, potassium or cesium), CF2=CFOCF2(CF2CF2)1-
．． (2) I CF20F2 (CF20F2), at least one compound represented by ~5I. Any composition can be selected as the composition of these fluorine-containing monomers, but preferably the fluorine-containing monomer capable of introducing an ion exchange group by reaction has a weight of 5 to 95% of the total monomer weight, and the fluorine-containing divinyl ether has a weight of 95% to 95% of the total weight of the monomers. A composition of ~5% by weight is preferred. In order to obtain a high ion exchange capacity, it is preferable that the monomers that can be converted into ion exchange groups by reaction account for at least 30% by weight of the total monomers. In addition, 0Rf (Rf is a perfluoroalkyl group having 1 to 10 carbon atoms) CF2=CF, CF2:C
FCJICF3CF=CF2. CF20F2. CF, =
Fluorine-containing monomers such as CH2, fine powders, oligomers such as polytetrafluoroethylene, copolymers of tetrafluoroethylene and hexafluoropropylene, copolymers of tetrafluoroethylene and alkyl vinyl ether, or perfluorinated chloride, perfluoroethylene, etc. It is also possible to polymerize by adding a solvent such as heptane, polyfluoroether, trichlorotrifluoro-a-ethane, perfluoropolyether.

In the present invention, examples of the fluorine-containing nitrogen compound obtained by reacting N2F4 with a polyfluoroacetylene compound, which is an initiator for copolymerization, include CF2O:
CF2O(N
F2) = C(NF2) CF3 or CF3CF (NF2)
C(NF)CF3; CF2O(NF2) = C(NF2 obtained by reacting N2F4 with CF3C≡CC,F)
) C4F9 or CF3CF (NF2)=C(NF)C
It is preferable to use one kind of 4F, or a mixture of xN or more. In addition, CF3 (jc'F, R, c=cR,=
(Here, Rf, RfI.

is a perfluoroalkyl group having 1 to 10 carbon atoms).

CI (CF2CF2), ~5 C=C(CF2C
F 2) 1”, 5 CLH (CF,) 5C yo C (C
F, ), HCF3C-C-CF2CF2゜c6a,c
-ccp3. C6H3C≡CC, H5, etc. can also be used. The amount of these initiators added is 0 for seven months.
．． 1~201! The weight is preferably 1 to 10 weight.

Polymerization temperature is θ℃~200℃, preferably 40℃~150℃
℃, and it is also good to carry out the polymerization by increasing the polymerization temperature stepwise. Further, the polymerization is preferably carried out in the presence of an inert gas such as nitrogen. The form of polymerization may be any method such as bulk polymerization, solution polymerization, *turbid polymerization, etc. Bulk polymerization is preferably recommended.

Depending on the purpose of use, the bulk polymer can be cut into particles or into a film with a size of 10 to 1000 μm. In addition, during bulk polymerization, polytetrafluoroethylene, a copolymer of ethylene and tetrafluoroethylene, a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether, a copolymer of tetra7/I/oethylene and perfluorovinylsulfonyl fluoride are used. , a copolymer of tetrafluoroethylene and perfluorovinylcarboxylic acid ester, polyvinylidene heptadide, polyvinyl chloride, polypropylene, etc., woven fabrics such as nets, nonwoven fabrics, nets, and films.

Porous films, tubes, etc. can be used as reinforcing materials or supports during polymerization. Or stainless steel, titanium, or nickel.

A wire mesh made of platinum or the like or a metal such as punched metal can be used as a reinforcing material.

It is preferable that the thickness of the polymer obtained in this manner is i+ufi so that it becomes a thickness of 5 to 500 .mu.m. Alternatively, it is also possible to mold the mold into any desired shape by pouring the mixture of nanatsuma into a mold. A certain ψ can also be coated by placing a coating object in the center of a mold, pouring a mixture of seven polymers, and polymerizing it. Alternatively, the substrate can be coated by pouring the seven-mer mixture onto the substrate and polymerizing it in that state.

In order to introduce ion exchange groups into the copolymer thus obtained, a cation exchange resin or a cation exchange membrane can be obtained by treating the copolymer with an alkaline solution of KOH or NaOH. Alternatively, an anion exchange resin or an anion exchange resin membrane can be obtained by treating a sulfonyl halide group or a carbonyl halide group with a polyamine such as ethylenediamine to convert it into an anion exchange group. Furthermore, a part or all of the copolymer can be converted to a carboxyl radical by reacting an oxidizing agent or a reducing agent to the copolymer having a sulfonyl chloride group.

The surface of the ion exchange membrane obtained by the method described above can also be roughened by grinding. Also TiO
Thin film made of □-ZrO□-polytetrafluoroethylene etc., RuO2-In20. - Polytetrafluoroethylene.

A thin film made of N-polytetrafluoroethylene, pt-polytetrafluoroethylene, etc.

A vapor-deposited metal film or the like can be bonded to one or both sides of the film.

The resin having a crosslinked structure of the present invention is heat resistant.

It has excellent corrosion resistance and two-dimensional stability, so it can be applied to various fields.

For example, it can be used as a gas nut, spacer, coating material, adsorbent, catalyst, or carrier for catalytic reaction.
It can be used as a diaphragm for evaporation, gas separation, reverse osmosis, diffusion dialysis, electrodialysis, etc., and as an electrolytic diaphragm for alkali chloride.

〔Example〕

Examples of the present invention will be described in more detail below, but it goes without saying that the present invention is not limited to such explanations.

Example I CF2=CFOCF2CF20CF=CF25 parts by weight and CF2=CFOCF2CF2COoCH35 parts by weight, CF3C≡CCF, and CF2 synthesized from N2F4
O(NF2) = C(NF2) CF360% and C
F3C(NF)CF(NF,)CF340% mixture 0
．． The mixed solution to which 5 parts by weight was added was placed in a stainless steel autoclave, and after purging with reduced pressure and nitrogen, it was heated at 75°C for 2 hours.
Polymerization was carried out for 4 hours. When the obtained copolymer was washed with trichlorotrifluoroethane, 9.1 parts by weight of copolymer was obtained. When we took a part of this copolymer and examined its infrared spectrum, we found that it was based on vinyl ether A/D < 1840.
There was no absorption of cst-1, and it was clear that it was crosslinked.

After cutting this copolymer to a thickness of 200μ, Na, O
15 parts by weight of H, 30 parts by weight of dimethyl sulfoxide, 5 parts by weight of ice
A cation exchange membrane based on sodium carbonate was obtained by treatment with a hydrolysis solution containing 5 parts by weight at 80° C. for 2 hours. After converting the carboxylic acid groups of this film into acid stars using HCJ and washing with water, the film was placed in a saline solution at 0.0%. Neutralization titration using a 1N-NaOH aqueous solution showed an exchange capacity of 1.61 meq/jl dry membrane. Furthermore, this film was placed in a 30% NaOH aqueous solution at 150°C.

After 3 days of immersion, there was almost no change in morphology or exchange capacity.

Examples 2 to 14 Various perfluorodivinyl compounds as shown in Table 1 and various perfluorovinyl ethers convertible into ion exchange groups were prepared using the initiators also shown in Table 1 under -all polymerization conditions. After washing with trichlorotrifluoroethane and drying under reduced pressure at 60° C., the polymerization rate was determined by measuring the weight. Furthermore, the ion exchange capacity was determined by elemental analysis of this polymer.

It should be noted that all the copolymers had no absorption <1840 cm-'' based on perfluorovinyl ether groups, and it was clear that they had a crosslinked structure.

Example 15 1 part by weight of a perfluorohexane solution consisting of 20% CF2O(NF2)C(NF2)CF3 and 10% CF3C(NF)CF3 was added to 6 parts by weight of CF2=CFOCF2CF3C00CH36 parts by weight of CF2=CFOCF2CF, 0CF=CF23. The autoclave was charged into a stainless steel autoclave, and after the atmosphere was replaced with liquid nitrogen under reduced pressure, 1 part by weight of tetrafluoroethylene was charged into the autoclave, and the mixture was swollen at a temperature of 50° C. for 3 days under nitrogen pressure made by 10 Co., Ltd. to obtain a bulk polymer. When this polymer was cut and the exchange capacity was measured by the method of Example 1, it was found to be 1.9 meq.
/I indicates the exchange capacity of dry resin.

Example 16 Made of polytetrafluoroethylene, 0.15 dew thick, 20
CF on mesh cloth, = CFOCF3CF2C00CH
310 copies, CF2=CFOCF3CF2CF20CF
= A mixed solution consisting of 210 parts of CF, 1 part of finely powdered polytetrafluoroethylene, and 0.5 part of the initiator of Example 1 was applied, both sides were sandwiched between stainless steel plates, and the mixture was placed in an autoclave. The tubes were then incubated at 60°C for 1 day. After polymerization, it was hydrolyzed by the method of Example 1 to obtain a cation exchange membrane having carboxylic acid groups.

The effective membrane resistance of this membrane is 0. When measured in 1N-NaOH, it was 22 Ωd.

Using this cation exchange membrane, a two-chamber electrolytic cell (effective membrane area: 10 ad, anode: ruthenium-brooded titanium electrode, cathode: iron, distance between waist and cathode = 4 mm, membrane and anode in close contact,
Using an electrolysis temperature of 90 DEG C. and a current density of 30 A/d, a 5N aqueous sodium chloride solution was supplied to the anode chamber and water was supplied to the cathode chamber to produce a 30-N aqueous sodium chloride solution. As a result, the sliding voltage was 3.31V.

The current efficiency was 9751I.

1 part, 20 parts of trichlorotrifluoroethylene, and 0.1 part of Parrydocks 16 (bis(4-t-butylmicrohexyl)peroxydicarbonate)) were placed in a stainless steel autoclave, and the mixture was degassed under reduced pressure with liquid nitrogen. After that, tetrafluoroethylene was introduced under a pressure of 105 °C, and polymerization was carried out at 60°C for 6 hours to obtain 10.8 parts by weight of a polymer. This polymer was dried under reduced pressure, pulverized, and then compression molded at 250° C. to obtain a film with a thickness of 250 μm. (When this film was hydrolyzed using the method of Example 1 and the exchange capacity was measured, it was found that 0.90 m5 (CF
25o□F 10 parts, CF2=CFOCF2CF2
0CF=CF, 41 and CF3C(NF,)C(NF2
)CF310% and CF3CF (NF2) C(N
F) After immersing the above film in a mixed solution consisting of 1 part of a catalyst with the composition rumored to be CF384 at 30°C for 4 hours, the adhering solution was wiped off with a mouthpaper - sandwiched between glass plates and placed in an autoclave under a nitrogen pressure of 6z. Polymerization was carried out at 70°C for 1 day. After polymerization, it was hydrolyzed by the method of Example 1 and the exchange capacity was measured to be 1.1 meq/g of dry resin. The degree of expansion and contraction of the impregnated polymerized membrane was smaller than that of the untreated membrane. When this film was subjected to electrolysis using the method of Example 16, the sliding voltage was 3.20 V and the current efficiency was 61%.

Claims (1)

[Scope of Claims] 1) A fluorine-containing vinyl compound having a functional group that can be converted into an ion exchange group by reaction with a fluorine-containing divinyl compound,
A method for producing a fluorine-containing ion exchange resin characterized by copolymerizing a fluorine-containing nitrogen compound in the presence of a fluorine-containing nitrogen compound obtained by reacting a polyfluoroacetylene compound with N_2F_4.
CF_3C (NF_2) obtained by reacting F_4 =
C(NF_2)CF_3 and/or CF_3CF(
3) The fluorine-containing nitrogen compound is CF_3C≡CC_4F_9
CF_3C (NF
_2)=C(NF_2)C_4F_9 and or CF
The manufacturing method according to claim 1, wherein _3CF(NF_2)=C(NF)C_4F_9