JPH043418B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a fluorine-containing polymer film, and more particularly to a method for easily producing a useful perfluoro polymer film. Fluorine-containing polymer films, especially perfluorinated polymer films, have a number of features that are not found in ordinary hydrocarbon films, so they are used in a wide variety of fields. There is. For example, a typical example of an application that takes advantage of its excellent chemical resistance and heat resistance is the ion exchange membrane for salt electrolysis, which has been widely researched all over the world in recent years. Conventionally, such fluorine-containing polymer films have generally been produced through a multi-step process of polymerizing the corresponding monomers and then forming the resulting polymer into a film. For example, in the production of a polytetrafluoroethylene film, tetrafluoroethylene is first sucked into water containing a radical initiator and polymerized under emulsification or suspension to obtain a dispersion of polytetrafluoroethylene powder or granules. The fine powder for molding is separated from the water by coagulating the dispersion, and then used for the next process to form a film. Examples of methods for making a film include compression molding the fine powder mentioned above to create a cylindrical floc, and cutting this to produce a film, and adding an extrusion aid to the powder to improve lubricity. do,
This method involves preforming the film into a film, and then rolling and sintering the film using hot rolls. On the other hand, even in the case of a copolymer film of tetrafluoroethylene and perfluoroalkyl vinyl ether, which has a significantly lower melt viscosity and improved moldability than polytetrafluoroethylene, polymerization for producing powder of the copolymer is difficult. Two steps are required to produce the film: a process and a film forming process. Therefore, the method for producing a fluorine-containing polymer film by forming a polymer into a film as described above requires at least a polymerization step and a film forming step, and therefore, a large amount of equipment and complicated operations are unavoidable. Also,
In such a multi-step production method, the polymer is molded by temperature and pressure in the film forming process, which may result in an undesirable polymer film due to thermal history. Furthermore, since a polymer having a crosslinked structure is difficult to form into a film, there is a problem in that it is not possible to obtain a fluorine-containing polymer film having a crosslinked structure. The inventors of the present invention have conducted extensive research in view of various problems in the method for producing a fluorine-containing polymer film as described above. As a result, by taking advantage of the property of fluorine-containing monomers to easily form a thin layer and further polymerizing the thin layer of the fluorine-containing monomer, we were able to achieve surprisingly good results. The inventors have discovered that a useful fluorine-containing polymer film can be easily obtained, and have thus come to provide the present invention. That is, according to the present invention, there is provided a method for producing a fluorine-containing polymer film, characterized in that a fluorine-containing vinyl monomer is formed into a thin layer and then polymerized. Note that the film referred to in the present invention is not particularly limited in thickness, and is a general term including membranes and sheets. The production method of the present invention simplifies the film formation (formation of a thin layer) and polymerization of a fluorine-containing vinyl monomer and performs them sequentially in one step, and the fluorine-containing vinyl monomer has the following good properties. based polymer film can be obtained. For example, in the present invention, a fluorine-containing polymer film with almost no thermal history and excellent mechanical strength can be obtained because film forming using temperature and pressure such as thermal fusion of the polymer or rolling is not required. Furthermore, in the present invention, a fluorine-containing polymer film having a crosslinked structure can be easily produced by mixing a fluorine-containing polyvinyl monomer, particularly a fluorine-containing divinyl monomer, with a fluorine-containing vinyl monomer. . Furthermore, in the present invention, by copolymerizing while controlling and supplying gaseous fluorine-containing olefin from the gas phase to a thin layer of fluorine-containing vinyl monomer, the composition differs in the thickness direction, and a few μ It is also possible to produce a fluorine-containing polymer film having an uneven porous structure consisting of particles of 10 to several tens of microns. Therefore, the present invention uses a fluorine-containing vinyl monomer having an ion exchange group or a functional group that can be exchanged with an ion exchange group to be described later, thereby producing a fluorine-containing vinyl monomer having the above-mentioned properties that is particularly useful as a diaphragm for salt electrolysis. It is extremely suitable for producing cation exchange membranes. That is, according to the present invention, it is possible to obtain a fluorine-containing cation exchange membrane having excellent mechanical strength and dimensional stability and having a porous structure on the surface suitable for a diaphragm for electrolysis. The present invention will be explained in detail below. The fluorine-containing vinyl monomer used in the present invention is not particularly limited as long as it is a fluorine-containing, particularly perfluorinated, organic compound that generally has one or more polymerizable double bonds and is liquid under polymerization conditions. For example, it is expressed by the following general formula. CF ₂ = CF−(O) _l {−(CF ₂ ) _n −(CFX) _o −
(O) _p } - _r (CFX ¹ ) _q -Y where l, p are 0 or 1; m, n, r, q
is an integer from 0 to 4; X, X ¹ is F, H, Cl, CF ₃ ; Y
is −SO ₂ −A {A=OM (M is H, metal ion),
F, Cl, Br}, -COA (A is as described above), -CN, _-CF3 or -CF= _CF2 . A representative example that is specifically and preferably used based on the above general formula is that when Y is −CF ₃ CF ₂ =
CFOCF ₂ CF ₂ CF ₃ ,

[Formula], etc. If Y is -SO ₂ A, -COA or -CN and is a cation exchange group or a functional group that can be easily converted into a cation exchange group, CF ₂ = CFOCF ₂ CF ₂ CF ₂ SO ₂ F, CF ₂ = CFOCF ₂ CF ₂ CF ₂ COOR, CF ₂ = CFOCF ₂ CF ₂ CF ₂ CN, CF ₂ = CFOCF ₂ CF ₂ CF ₂ COF, (In the formula, R is an alkyl group such as methyl or ethyl group)
etc. Furthermore, when Y is −CF=CF ₂ , it indicates an inclusion element divinyl monomer, and a typical example thereof is CF ₂ =
CFCF=CF ₂ , CF ₂ =CFCFCF=CF ₂ , CF ₂ =
CFFCFCCF=CF ₂ , CF ₂ = CFOCF ₂ CF ₂ OCF=CF ₂ , CF ₂ = CFOCF ₂ CF ₂ CF ₂ OCF=CF ₂ , CF ₂ = CFOCF ₂ CF ₂ OCF 2 CF ₂ = CF _{2 ,} etc. In addition, generally

[Formula] and

A fluorine-containing vinyl monomer represented by the formula can also be suitably used in the present invention.
Here, R _f is a perfluoroalkyl group represented by C _o F _2o+1 , and preferably n is 4 to 10, while R 1 f is a perfluoroalkyl group represented by C o F 2o+1, while R ¹ _f is a perfluoroalkyl group represented by C o F 2o+1, and R 1 _f is a perfluoroalkyl group represented by C o F 2o+1.

It is a perfluoroalkylene ether group represented by the formula, and m is 1 to 3. In the present invention, one or more fluorine-containing vinyl monomers as shown above are used, or one or more fluorine-containing vinyl monomers are used to make the desired fluorine-containing polymer film into a copolymer having characteristics suitable for the intended use. A mixture of monomers can also be used. In particular, when one of the fluorine-containing vinyl monomers is used that has a cation exchange group or a functional group that can be easily converted into a cation exchange group, the dimensional stability of the resulting film is of great importance. Ru. Therefore, in such cases, by adding an appropriate amount of a fluorine-containing divinyl monomer, a film having a three-dimensional crosslinked structure and improved dimensional stability can be obtained. Furthermore, the liquid fluorine-containing vinyl monomer is mixed with a radical initiator if necessary. The radical initiator may be one that dissolves in the fluorine-containing vinyl monomer in the amount necessary for polymerization (usually about 0.1 to 10 mol% relative to the fluorine-containing vinyl monomer), and that decomposes at the polymerization temperature. It is sufficient as long as it generates radicals and initiates polymerization. For example, hydrocarbons include ditertiary butyl peroxide, tertiary butyl cumyl peroxide, and 2,5-dimethyl-2,5-di(tertiary butyl peroxy).
Dialkyl peroxides such as hexane, diacetyl peroxide, diisobutyryl peroxide, dioctanoyl peroxide, dilauroyl peroxide, dibenzoyl peroxide, diisopropyl peroxide, di-n-propyl peroxide, etc. Peroxydicarbonates such as oxydicarbonate, di-2-ethoxyethyl, peroxydicarbonate, other organic peroxides such as pooxyesters, peroxyketals, ketone peroxides, azobisbutyronitrile In addition, perfluorodipropanoyl peroxide, perfluorodibutanoyl peroxide, perfluorodipentenoyl peroxide, perfluorodihexane having a fluorine-containing alkyl group, etc. perfluorodiacyl peroxides such as peroxide, perfluorodiheptanoyl peroxide, perfluorodioctanoyl peroxide, perfluorodinonanoyl peroxide, perfluorodidecanoyl peroxide, and H or Cl at the ω-position. Polyfluorodiacyl peroxides, diacyl peroxides containing an ether group in the perfluoroalkyl group, such as perfluorodipropoxypyropionyl peroxide, perfluorodiisopropoxypropionyl peroxide, etc. are preferably used. Other perfluorodialkyl peroxides such as ditrifluoromethyl peroxide, others, N ₂ F ₂ , N ₂ F ₄ , nitrogen fluorides, CF ₃ C
Fluorine-containing compounds having a difluoroamino group such as (NF ₂ )=C(NF ₂ )CF ₃ can also be used.
Among these radical initiators, diacyl peroxides and peroxydicarbonates are preferable because they polymerize quickly and are particularly preferable because they do not cause coloring of the film obtained from polyfluoro-based diacyl peroxides. On the other hand, in the presence of these radical polymerization initiators,
It is also possible to initiate polymerization using energy such as ultraviolet rays, X-rays, α-, β-, and γ-rays in the absence of the polymer. Next, in the present invention, there are no particular limitations on the method for forming a thin layer of the fluorine-containing vinyl monomer. for example
(A) A method in which the fluorine-containing vinyl monomer is cast onto a flat plate of glass, metal, etc. (B) A method in which the fluorine-containing vinyl monomer is cast onto the surface of a liquid such as mercury in which it is not substantially dissolved. , (C) A method in which a fluorine-containing vinyl monomer is supplied into a reactor having a cylindrical inner surface, and the cylinder is rotated with the center axis of rotation horizontally to form a thin layer on the inner wall of the reactor, ( D) In the method (C) above, a method is adopted in which the cylinder is rotated with its central axis of rotation perpendicular, and the centrifugal force is used to form a thin layer of the fluorine-containing vinyl monomer on the inner wall of the reactor. Of course, in order to stably form a thin layer, the presence of fine powder, fibrils, filaments, or net-like materials made of a fluorine-containing, preferably perfluoro-based polymer in the thin layer is important. This is an effective means of improving the mechanical strength of fluorine polymer films. Of the four methods mentioned above, methods (A) and (B) require a pre-step to ensure the formation of a thin layer before polymerizing the fluorine-containing vinyl monomer, and a flat plate separate from the polymerization reactor is required. Alternatively, since a specific liquid is required, the equipment becomes excessively large, especially when forming a thin layer over a large area, and it is also quite difficult to form the thin layer to a uniform thickness. On the other hand, in methods (C) and (D), polymerization can be carried out after forming a thin layer of fluorine-containing vinyl monomer in the polymerization reactor, or while forming a thin layer, so the equipment and operation are also less. It is simple and advantageous. In particular, method (D) is recommended because it is easier to form a thin layer of fluorine-containing vinyl monomer to a uniform thickness even over a large area than method (C). The thickness of the thin layer is important because it becomes the approximate thickness of the film after polymerization, and in order to form the thin layer, the area where the fluorine-containing vinyl monomer spreads on the inner surface of the flat plate, liquid, or cylinder and the charged impurity are important. The thickness of the thin layer can be determined from the capacity of the fluorinated vinyl monomer. According to the method of the present invention, a fluorine-containing polymer film having a thickness of usually about 10 μm to 1 mm can be easily produced. The thin layer thus formed is then placed under polymerization conditions to initiate and complete polymerization. When polymerizing a thin layer of fluorine-containing vinyl monomer formed by methods (A) and (B), the polymerization reactor should be kept at a temperature necessary to maintain the thin layer horizontally and to initiate and complete the polymerization. Gases such as nitrogen that are not involved in polymerization are added to prevent evaporation of fluorine-containing vinyl monomers during polymerization, and copolymerization components such as tetrafluoroethylene, chlorotrifluoroethylene, and fluorine are added as necessary. Any structure that can withstand the pressure of a gas component such as a fluorine-containing olefin such as vinylidene chloride hexafluoropropylene may be used. on the other hand,
In methods (C) and (D), since the fluorine-containing vinyl monomer is polymerized while being formed into a thin layer in the reactor, it is possible to maintain and control the temperature, and the above-mentioned pressure-resistant structure is required. In addition, the structure of the reactor is important because the fluorine-containing vinyl monomer is cast and a thin layer is produced.
Specifically, in method (C), polymerization is carried out while forming a thin layer of the fluorine-containing vinyl monomer on the surface of the cylinder while horizontally rotating the center of the cylinder inside the reactor around the axis of rotation. In addition, in method (D), polymerization is carried out while forming a thin layer of fluorine-containing vinyl monomer on the surface of the cylinder by centrifugal force while rotating vertically around the center of the cylinder inside the reactor as the rotation axis. For this reason
When forming a thin layer of fluorine-containing vinyl monomer using methods (C) and (D), the reactor is cylindrical, and the cylinder is rotated horizontally or vertically to proceed with polymerization and solidify. is required. If this requirement is satisfied, in order to increase production efficiency, several cylinders are set in a straight line in the reactor with their centers aligned with the rotation axis, and fluorine-containing vinyl monomer is produced in each cylinder. Several cylinders with different radii are placed inside the cylinders in descending order of radius with their centers aligned with the axis of rotation, and a fluorine-containing vinyl monomer is introduced into each cylinder to carry out polymerization. This method is also a preferred embodiment of the present invention since it is possible to obtain several films at once through one polymerization. On the other hand, in the method (C), the rotation speed is usually about 10 to 500 rpm, which is sufficient to rotate the cylinder horizontally so that the fluorine-containing vinyl monomer does not accumulate at the bottom of the cylinder. (D)
Method (C) requires a higher rotational speed than method (C) in order to form a thin layer using centrifugal force. Although it varies depending on the specific gravity and viscosity of the fluorine-containing vinyl monomer used, it is usually desirable to set the speed at about 500 to 5000 rpm. Of course, it is not necessary to maintain the above-mentioned rotational speed throughout the polymerization, and the rotational speed can be reduced when the polymerization has progressed to a certain extent and the viscosity has increased, or it can be stopped if the polymerization has progressed further. The temperature during polymerization is determined by the half-life temperature in 10 hours of the radical initiator used. For example, perfluorodipropoxypropionyl peroxide has a half-life temperature of about 12°C, diisopropyl peroxydicarbonate has a half-life temperature of about 40°C, dibenzoyl peroxide has a half-life temperature of about 80°C, and di-tertiary butyl peroxide has a half-life temperature of about 120°C. The polymerization temperature can be changed depending on the radical initiator used, such as the degree of polymerization. However, many fluorine-containing vinyl monomers have low boiling points, and when a hydrocarbon-based radical initiator is used, the resulting film may be colored when polymerized at high temperatures.
Considering these points, it is preferable to carry out the polymerization in a temperature range of 0°C to 100°C. For this reason, it is preferable that the initiator used also has a half-life temperature of 10 hours within this temperature range, and more preferably a perfluorinated initiator. The pressure during polymerization differs depending on the following two embodiments. One is that it varies depending on the temperature during polymerization and the fluorine-containing vinyl monomer used; This is a case where polymerization is carried out in a state where an uninvolved inert gas such as nitrogen is sealed under pressure. In this case, the purpose can be achieved by applying a pressure of about 10 kg/cm ² . The other method is to apply a gaseous fluorine-containing olefin, such as tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride, hexafluoroethylene, which can be copolymerized with the fluorine-containing vinyl monomer, from the gas phase to a thin layer of the fluorine-containing vinyl monomer. This is a case where copolymerization is carried out while supplying propylene or the like. In this case, in order to obtain a film with the desired composition, polymerization is carried out by applying pressure to the fluorine-containing olefin, and usually the pressure of the fluorine-containing olefin is 0 to 200
Kg/cm ² copolymerization reaction is carried out. When the fluorine-containing olefin is polymerized while being supplied in a thin layer from the gas phase in this way, it has the following advantages, unlike the case where a thin layer of the fluorine-containing vinyl monomer is simply polymerized. First, a porous structure is formed in which particles of several to several tens of microns are aggregated on the surface of the fluorine-containing polymer film that has come into contact with the fluorine-containing olefin. A fluorine-containing polymer film having such a surface structure has physical properties that are quite different from those of a smooth fluorine-containing polymer film surface. Therefore, when the film of the present invention is used with other substances or as an ion exchange membrane for electrolysis as described below, it can fully exhibit its characteristics. On the other hand, in the case of conventional smooth fluorine-containing polymer films, chemical treatment with chemicals such as sodium naphthalene or mechanical treatment using asandoplast, abrasive rolls, etc. are required to impart such properties. However, in the present invention, it is possible to impart such characteristics at the same time as forming a film. Secondly, the coexistence of a fluorine-containing olefin improves the polymerization yield and polymerization rate compared to when a fluorine-containing vinyl monomer is used alone, which is often preferable. Furthermore, when the pressure of the fluorine-containing olefin is polymerized by varying the pressure over a wide range, a film in which the composition is distributed with a certain gradient in the thickness direction of the resulting fluorine-containing polymer film can be obtained. The polymerization time depends on the type of fluorine-containing vinyl monomer used,
Although it cannot be absolutely determined depending on the polymerization temperature, the radical initiator used, and the presence or absence of a fluorine-containing olefin, the film of the present invention can usually be produced in a polymerization time of about 1 to 50 hours. After a predetermined polymerization time has elapsed, if necessary, the rotation of the reactor is stopped, the pressure inside the reactor is released, or if necessary, the inside of the reactor is replaced with an inert gas such as nitrogen, and then the reactor is opened. It is observed that the solidified fluorine-containing polymer film is usually formed in close contact with the inner surface of the cylinder into which the fluorine-containing vinyl monomer has been cast. The produced film usually has low adhesion to other substances, so it can be easily peeled off from the inner wall of the reactor and taken out. It is often preferable to apply a mold release agent such as fluorine-based oil to the inner surface of the reactor prior to polymerization. The use of a mold release agent is particularly effective when a portion of the inner surface is rusted or uneven. The film thus obtained is, if necessary, immersed in a fluorine-containing solvent such as Freon 113 or a chlorine-containing solvent such as carbon tetracarbonate at room temperature or under heating to remove unreacted fluorine-containing vinyl monomers. The film of the present invention can be obtained by extracting and removing the oligomers and low molecular weight oligomers. On the other hand, when a fluorine-containing vinyl monomer having a cation exchange group or a functional group that can be easily converted into a cation exchange group is used,
Prior to use as a cation exchange membrane, the following post-treatment is required. For example −SO ₃ H,
-COOH, etc., in order to change the metal ion type to the sodium type, for example, in order to swell the aqueous solution or film of common salt or caustic soda and facilitate the ion exchange reaction, use methanol, ethanol, isopropanol, dimethyl, etc. instead of the aqueous solution as necessary. The film can be converted into a salt form by immersing it in a solution containing an organic solvent capable of swelling the film, such as sulfoxide and dimethylformamide, at room temperature or under heating for several to ten-odd hours.
On the other hand, −SO ₂ F, −SO ₂ Cl, −SO ₂ Br, −COOR, −
When a film is produced using a fluorine-containing vinyl monomer having COF, -COCl, -COBr, and -CN, a hydrolysis reaction is required to convert it into a cation exchange group. In this case, the film is placed in a mixed solvent of water containing about 10% by weight of an alkali metal hydroxide, such as caustic soda, and the above-mentioned organic solvent.
The hydrolysis reaction is completed by heating to about 100°C and soaking for several to several tens of hours. The film obtained by the present invention can be suitably used in the same manner as conventional films, including fields where fluorine-containing films have been conventionally used, and by taking advantage of the numerous features of the film of the present invention. In particular, when the fluorine-containing vinyl monomer is a perfluoro type having a cation exchange group or a functional group that can be easily converted into a cation exchange group, and also contains a perfluoro divinyl compound, it will not be hydrolyzed. When used as a cation exchange group, the dimensional stability is significantly improved and it can be suitably used as a cation exchange membrane for aqueous halide electrolysis, which is currently being actively researched. In addition, when the fluorine-containing vinyl monomer used has a sulfonic acid group or a functional group that can be easily converted into a sulfonic acid group, when the obtained film is used as an ion exchange membrane for salt electrolysis, the composition changes. As a result, current efficiency may be poor.
In this case, any of the improvement methods proposed in many patents can be used. For example, JP-A-52-24177, JP-A-57-58374, JP-A-58-
The current efficiency can be improved by changing the sulfonic acid groups in the surface layer portion or the entire film to carboxylic acid groups by applying the methods described in publications such as No. 34805 and Japanese Patent Application No. 58-26349. Furthermore, when polymerization is carried out while supplying a fluorine-containing olefin, one side of the fluorine-containing polymer film obtained by the present invention (the surface in contact with the fluorine-containing olefin) has porous pores with irregularities made of particles of several to several tens of microns. Because of its textured structure, it has surface properties that are different from conventional smooth film surfaces. Therefore, for example, when the film of the present invention is used as a cation exchange membrane for salt electrolysis, by directing this side toward the cathode, the adhesion of air bubbles (hydrogen) is significantly reduced compared to a smooth film, and the adhesion of air bubbles is reduced. Increase in electrical resistance can be reduced. This can be said to have surface properties suitable for ion exchange membranes for electrolysis. Furthermore, by attaching catalytic substances for anodic reaction and cathodic reaction to both surfaces of the film, it can also be used as so-called SPE. in this case,
The fluorine-containing polymer film of the present invention obtained by polymerization using a flat plate or cylinder having an uneven and porous structure in contact with the fluorine-containing vinyl monomer has uneven and porous surfaces on both surfaces. Needless to say, it has a structure that helps reduce the adhesion of air bubbles, as well as adhesion and retention of these catalyst substances. Furthermore, many proposals for improving ion exchange membranes for electrolysis can also be applied to the film of the present invention. The present invention will be explained below using Examples, but the present invention is not limited thereto. Example 1 A radical initiator was placed in a glass cylinder with an inner diameter of 1.6 cm and a length of 10 cm, the inlet of which was narrowed so that the liquid inside would not spill when the cylinder was held horizontally.

A 5% solution of Freon 113 of [Formula] is added to the raw material fluorine-containing vinyl monomer. was added in an amount equivalent to 1 mol%. Next, the Freon solution was cooled to −5° C. and the pressure was reduced to evaporate Freon 113, which was a solvent. Return to normal pressure while cooling, approx.
1.4g of added. Thereafter, the glass cylinder was inserted into a cylindrical stainless steel reactor equipped with a pressure gauge, with the rotation axes aligned. The reactor was cooled with liquid air and the pressure inside the reactor was reduced. Next, tetrafluoroethylene was charged into the reactor at a standard concentration of 6 kg/cm ² . Furthermore, the reactor was placed in a dryer whose temperature was adjusted to 30°C, and the reactor was held horizontally and connected to a motor, and polymerization was continued while rotating at about 50 rpm.
After about 3 hours at 30°C, the pressure of tetrafluoroethylene had decreased to 2.0 Kg/cm ² . At this point, the reactor was removed and the tetrafluoroethylene pressure was released to open the reactor. When the glass cylinder was removed, a translucent fluorine-containing polymer film was found on the inner wall of the cylinder. A cylindrical film was taken out, cut open with scissors, and the thickness of the film was measured and found to be 120 to 130μ. The film was strong and flexible. Caustic soda, dimethyl sulfoxide,
In a mixed solution of water at a ratio of 3:7:11 (weight ratio)
Soaked at 90℃ for 15hrs. The exchange capacity of the obtained film was determined by the neutral salt decomposition method. As a result, 0.75
Milliequivalents/gram dry matter. Furthermore, we observed both surfaces of the film using a scanning electron microscope.
The surface in contact with the inner wall of the cylinder was flat even when observed at a magnification of 500 times, but the other surface was a porous surface with irregularities consisting of particles of 2 to 15 microns. Example 2 Instead of 0.3g CF ₂ = CFOCF ₂ CF ₂ OCF = CF ₂ and 0.9g A film was produced using the same method and equipment as in Example 1, unless otherwise specified, except that a mixture of the above was used. When polymerization was carried out for 2.5 hours at a polymerization temperature of 35℃, the pressure of 6Kg/ ^cm2 of tetrafluoroethylene was
It decreased to 2.5Kg/cm ² . At this point, the tetrafluoroethylene was removed from the reactor and the film was taken out. As in Example 1, it was a translucent and flexible film with a thickness of about 140 to 150 microns. For hydrolysis, it was immersed in the mixed solution of Example 1 at 90°C for 15 hours.
The exchange capacity was determined to be 0.86 meq/g dry matter. When the surface was observed using a scanning electron microscope in the same manner as in Example 1, the surface in contact with the inner wall of the cylinder was flat even at 1000x magnification, but the surface facing the gas phase had irregularities of 5 to 10 μm. A porous surface was observed. Further, in order to investigate the effects of CF ₂ =CFOCF ₂ CF ₂ OCF = CF ₂ , the film before hydrolysis was thermally fused together with the film obtained in Example 1. As a result, the film of Example 1 could be fused by pressing at a temperature of about 250°C, but the film of this example could not be fused even at a temperature of 300°C. As a result, CF ₂ = CFOCF ₂ CF ₂ OCF =
It was found that due to the addition of CF ₂ , a substantially crosslinked fluorine-containing polymer film was obtained in this example. Example 3

A radical initiator was added to [Formula] in the same manner as in Example 1. 5 mol% was dissolved. This liquid was cast onto a stainless steel plate (10 cm x 15 cm) with edges to prevent liquid from flowing around. Calculating from the weight increase, the liquid volume was equivalent to about 80μ. Next, the plate was placed horizontally into the reactor, the inside of the reactor was replaced with tetrafluoroethylene, and the pressure was further increased to 15 Kg/cm ² to seal the reactor. The temperature of the reactor was set to 25°C, and polymerization was continued for 8 hours. When the pressure decreased to 5 kg/cm ² , the reactor was opened and the plate was taken out, and an almost transparent film was found on the surface. Its thickness was 70 to 75μ, and it was flexible. According to observation using a scanning electron microscope, irregularities of about 5 to 20 μm were observed on the surface in contact with tetrafluoroethylene, but the other surface was flat. Example 4 5 mol% of diisopropyl peroxydicarbonate was dissolved in the solution. This liquid was poured onto the surface of the mercury in the shear dish. Next, the shears were further placed in the reactor, and the nitrogen pressure was 1 Kg/cm ² for 10 hours.
Polymerization was carried out at 30°C. Thereafter, when taken out from the reactor, a transparent film with a thickness of about 0.2 mm was obtained. Example 5 CF ₂ = CFOCF ₂ CF ₂ CF ₂ SO ₂ C and To the fused solution with a molar ratio of 1:4, add the peroxide solution used in Example 1 concentrated to 70%.
The equivalent of 10 mol% was added. Next, film formation was performed using the method and apparatus of Example 1. That is, the liquid mixture was added to a glass cylinder to form a thin layer of approximately 0.5 mm. The pressure of tetrafluoroethylene is 8
Polymerization was carried out at Kg/cm ² at 50° C. for 2 hours at a rotation speed of 30 prm. The obtained film had a thickness of approximately 0.5 mm.
10% to hydrolyze the sulfonyl fluoride groups and carboxylic acid ester groups of the film.
It was immersed in a mixed solvent of methanol and water (1:1 by volume) containing NaOH at 80°C for 10 hours. When the exchange capacity was determined using the PH titration method, the total exchange capacity was 1.1.
Milliequivalent/gram dry matter, and the ratio of sulfonic acid groups to carboxylic acid groups was approximately the same as the ratio at the time of preparation. Example 6 in the same manner as in Example 1. was added in an amount of 1 mol%. A liquid was added to the reactor used in Example 1 so that the thickness of the film obtained was approximately 160 μm. The reactor was then cooled with liquid air and then degassed. Raise the temperature to 0℃, 0.6
g of CF ₂ =CFCF=CF ₂ and 10 Kg/cm ² of tetrafluoroethylene were added. Further, in the same manner as in Example 1, polymerization was carried out at 25° C. for 5 hours at a rotational speed of 200 rpm, and the pressure decreased to 5 Kg/cm ² . When I opened the reactor and took out the film, it was approx.
A translucent film of 150μ was obtained. When the infrared absorption spectrum was measured using the ATR method, it was found to be 1420 cm ^-1
A strong absorption of sulfonyl fluoride groups was observed. Note that although the film before hydrolysis was pressed at 300°C, it could not be fused. Example 7 CF ₂ = CFOCF ₂ CF ₂ CF ₂ SO ₂ F1.6g and CF ₂ =
Example 3 to a mixed solution of CFOCF ₂ CF ₂ OCF=CF ₂ 0.3g
5 mol % of a radical initiator was added. Next, film formation was performed using the apparatus and method of Example 1. In other words, the pressure of tetrafluoroethylene is
When polymerization was carried out at 15Kg/cm ² at 10 rpm and 30°C for 8 hours, the pressure decreased to 1.3Kg/cm ² . When the reactor was opened and the film was taken out, it was a translucent flexible film with a thickness of approximately 110 μm. The obtained film was immersed in the hydrolysis solution used in Example 1 at 90° C. for 15 hours to determine the exchange capacity, which was 0.4 meq/g dry matter.
When the surface in contact with the tetrafluoroethylene was observed using a scanning electron microscope, it was found to be porous with irregularities consisting of particles of about 2 to 30 microns. Application example 1 The hydrolyzed film obtained in Example 2 was
It was immersed in 1N HCl at room temperature for 10 hours. after that,
It was washed with water to form an H ⁺ type film. In order to change the sulfonic acid group in the surface layer to a carboxylic acid group, JP-A-58
The following processing was performed in accordance with -34805. A germicidal lamp GL-15 (manufactured by Toshiba) is attached to the center of a stainless steel cylinder with an inner diameter of 8 cm and has two nozzles at the top and bottom. ^{The +} type film was attached with the porous side facing towards the center. Immerse the reactor in an oil bath and inject 50c.c./nitrogen from the bottom nozzle.
The temperature was increased to 160°C while being introduced through the upper nozzle. After the temperature was raised, the introduction of nitrogen was stopped, a vacuum pump was connected to the nozzle, and drying was carried out under reduced pressure for another hour. After drying, the inside of the reactor is -76cmHg
The pressure was reduced to 5 cmHg each of nitrogen oxide (NO) and nitrogen dioxide (NO ₂ ) from the nozzle,
Furthermore, nitrogen was introduced to bring the pressure to atmospheric pressure. The germicidal lamp was turned on and irradiation started. After 30 minutes of irradiation, the lamp was turned off and nitrogen was introduced into the reactor for cleaning. The film was taken out, a portion of it was cut out, and subjected to infrared spectrum measurement (ATR method). The remaining portion was heated in methanol-water (volume ratio 1/1) containing 20% NaOH for 30 minutes to remove ion exchange groups.
After converting into Na ⁺ form, it was subjected to dyeing tests, electrolytic tests, etc. As a result, in the infrared spectrum of the irradiated surface,
A medium-intensity absorption band due to carboxyl groups was observed at 1780 cm ^-1 . When changing to the Na ⁺ form, this absorption band was observed to shift to 1680 cm ^-1 . On the other hand, the absorption band of sulfonic acid groups at 1060 cm ^-1 observed on the unirradiated surface was hardly observed. Na ⁺
A part of the molded film (approximately 5 mm x 10 mm) was placed in a staining solution containing 100 mg of crystal violet dissolved in 100 c.c. of a mixed solvent of 0.5N-HCl-methanol (volume ratio 3:7) at room temperature. Soaked under 15hrs. After washing with water, the section was cut into thin sections using a microtome and observed under a microscope. As a result, 15 μm from one surface was not stained at all in a layered manner, and the other part was stained dark green. It was found that a carboxyl group was present. Table 1 shows the films that were made into Na ⁺ type after UV treatment and the films that were not UV treated.
The measurement results of the electrolytic test are shown. The electrolysis test was carried out using a two-chamber cell consisting of a titanium anode chamber and a nickel cathode chamber, with an effective current-carrying area of 0.1 dm ² . A titanium lath material coated with titanium oxide and ruthenium oxide was used as the anode, and a soft iron lath material was used as the cathode. Install a film between the anode chamber and the cathode chamber, with the anode in close contact with the cathode with a gap of 2 mm (for those irradiated with ultraviolet rays, the irradiated surface should face the cathode), and make sure that the anode chamber has a saturated Ca concentration of 0.5 ppm or less. Saline solution was supplied and discharged at a salt concentration of 3.5N. on the other hand,
Pure water was supplied to the cathode chamber so that the concentration of NaOH was 11N. The current density was adjusted to 30 A/dm ² and the temperature in the electrode chamber was adjusted to 90°C.

[Table] From the above results, it was found that the film of the present invention having a cation exchange group has good electrolytic performance over a long period of time by introducing carboxylic acid groups into the surface layer. Further, even when the distance between the cathode and the membrane was gradually shortened to bring them closer together, the cell voltage only decreased by the amount of solution resistance, and no increase in cell voltage due to adhesion of hydrogen bubbles was observed. Example 8 A cylindrical reactor with an inner diameter of 10 cm, a height of 5 cm, and a mirror finish on the inside was cooled to -10°C. A 3% perfluoronormal hexane solution was used, and an amount equivalent to 2 mol % based on the fluorine-containing vinyl monomer was added. As in Example 1, the pressure inside the reactor was reduced to remove perfluoronormal hexane by evaporation. The reactor was then immersed in liquid air and evacuated with a vacuum pump. Fill the reactor with nitrogen,
The temperature was raised to -10℃. Then,

[Formula] 4 g, CF ₂ = CFOCF ₂ CF ₂ OCF = 6 g of CF ₂ and 10 Kg/cm ² of tetrafluoroethylene were added into the reactor.
The center line of the cylinder of the reactor was set as the vertical axis of rotation, and a motor was precisely installed at the top of the reactor and a bearing at the bottom to enable high-speed rotation. The temperature around the reactor was set to 40°C, and the reactor was rotated at a rotation speed of 4000 rpm. After 5 hours, rotation was stopped and the reactor was removed from the motor. The pressure of tetrafluoroethylene is 6Kg/cm ²
It had declined to . When the internal pressure was released and the lid of the reactor was removed, a white translucent soft and flexible film was obtained on the inner wall. The thickness was approximately 100μ. When we measured the infrared absorption spectrum of the obtained film, we found that there was a methyl group in the vicinity of 2900 cm ^-1 .
Carboxylate groups range from 1300 to 1100 to 1780 cm ^-1
cm ^-1 A peak due to CF bond was observed. After hydrolysis to form a cation exchange membrane, the exchange capacity of carboxylic acid groups was measured and found to be 1.1 meq/g dry matter. On the other hand, when the surface was observed using a scanning electron microscope, it was observed that the surface in contact with tetrafluoroethylene had an uneven porous surface due to particles of 3 to 15 microns, but the other surface was flat. Further, an electrolytic test was conducted using the electrolytic conditions and equipment used in Application Example 1. Electrolytic tests were conducted with the porous surface facing the cathode side and with the cathode membranes in close contact with each other with a distance of 2 mm, respectively, and the electrolytic performance was investigated. As a result, when the porous side faced the cathode and the cathode film was placed in close contact with the cathode from a distance of 2 mm, the cell voltage decreased by approximately the solution resistance. When facing toward the side, the cell voltage increased by about 0.3V. The current efficiency and the salt concentration in the caustic were 95-96% and 20-30 ppm, respectively, in all cases. Example 9 Using the reactor of Example 1, the weight ratio of CF ₂ = CFOCF ₂ CF ₂ CF ₂ SO ₂ F and CF ₂ = CFOCF ₂ CF ₂ OCF ₂ CF ₂ OCF ₂ = CF ₂ was 5: CF ₃ C equivalent to 0.1 mol% in the mixture of 1
A solution of (NF ₂ )=C(NF ₂ )CF ₃ was added and polymerized. The polymerization was carried out at 80° C. for 15 hours while rotating at 100 rpm, with 20 kg/cm ² of nitrogen sealed in order to suppress evaporation of the fluorine-containing vinyl monomer. The obtained film was transparent and strong.

Claims (1)

[Scope of Claims] 1. A method for producing a fluorine-containing polymer film, which comprises forming a fluorine-containing vinyl monomer into a thin layer and then polymerizing it while forming the thin layer. 2. A patent characterized in that a liquid fluorine-containing vinyl monomer is present inside a polymerization reactor having a cylindrical interior, and a thin layer is generated by rotating the reactor with the center of the cylinder as the rotation axis. The method according to claim 1. 3. The method according to claim 2, characterized in that the rotation is performed with the rotation axis being horizontal. 4. The method according to claim 2, characterized in that the rotation is performed with the axis of rotation perpendicular. 5. The method according to claim 1, wherein a thin layer is formed by casting a liquid fluorine-containing vinyl monomer onto a flat plate. 6. The method according to claim 1, wherein the fluorine-containing vinyl monomer is cast on the surface of a liquid that does not substantially dissolve the fluorine-containing vinyl monomer to form a thin layer. 7 Claims 1 and 2, characterized in that the polymerization is carried out while supplying a gaseous fluorine-containing olefin copolymerizable with a liquid fluorine-containing vinyl monomer from a gas phase.
3. The method according to item 3, 4, 5 or 6. 8. The method according to claim 1, wherein the fluorine-containing vinyl monomer is a mixture of one or more types. 9. The method according to claim 1, wherein the fluorine-containing vinyl monomer contains a fluorine-containing divinyl monomer. 10. The method according to claim 7, wherein the fluorine-containing olefin is tetrafluoroethylene. 11. The method according to claim 1, wherein the fluorine-containing vinyl monomer has a cation exchange group or a functional group that can be easily converted into a cation exchange group. 12. The method according to claim 1, characterized in that a radical initiator is present in the fluorine-containing vinyl monomer in order to initiate polymerization. 13. The method according to claim 1, wherein the fluorine-containing polymer film is a cation exchange membrane or a film that can be easily exchanged into a cation exchange membrane. 14. The method according to claim 1, wherein the fluorine-containing vinyl monomer is a perfluoro compound. 15. The manufacturing method according to claim 1 or 13, wherein a fluorine-containing polymer film is used as a diaphragm for salt electrolysis.