JPS621964B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to electrolytic fluorination, and more particularly to a method for producing a fluoropolymer by electrolytic fluorination of a polymer compound. It is used as a raw material polymer compound in the present invention and has a molecular weight of 500 or more. In general, electrolytic fluorination requires that 1) the anhydrous hydrofluoric acid used is inexpensive, 2) it is easy to obtain highly fluorinated compounds, 3) the functional groups are easily preserved, and 4)
It has the advantage that the device is relatively simple. For this reason, attempts have been made to fluorinate many compounds by electrolytic methods, and some of them have been industrialized. However, in electrolytic fluorination, the larger the molecular weight of the compound used, the more likely it is that carbon bonds will be broken, especially in the case of compounds containing 10 or more carbon atoms. It has been said that it is difficult to obtain it efficiently by chemical methods. It should be noted that there have been few reports on electrolytic fluorination of polymer compounds, and the types of polymer compounds that have been used have therefore been limited. The present inventors have conducted various studies on electrolytic fluorination of polymer compounds. As a result, in electrolytic fluorination of polymer compounds, only polymers with an extremely low degree of fluorination can be obtained, and even if fluorination is performed to a high degree, severe polymer chain scission may occur at the same time. I found out that there are many things. However, it has already been discovered and proposed that a particularly solid, insoluble polymer compound can be efficiently fluorinated by placing it at or near the anode and electrolyzing it, and that a useful fluorinated product can be obtained. As a result of more detailed and intensive research, it was discovered that fluorine-containing polymers can be efficiently obtained by electrolytic fluorination of linear or branched polymer compounds having specific functional groups or atoms, and the present invention has been made. I was able to complete it. That is, the present invention uses anhydrous hydrofluoric acid as an electrolytic bath to form a linear or This is a method for producing a fluorine-containing polymer, which is characterized by electrolytically fluorinating a branched polymer compound. The characteristics of the present invention are that a polymer compound that is easily available is used, that no special electrolytic cell or electrolytic conditions are required, and that the resulting fluorine-containing polymer does not contain sulfonyl fluoride groups, nitrogen atoms, etc. For example, it is possible to efficiently manufacture the desired product. Furthermore, the present invention has various features such as being able to obtain not only a polymer having a molecular weight of 500 or more and a fluorine content of 40% or more, but also a fluorine-containing polymer containing no hydrogen atoms. The raw material used in the present invention is a linear or branched polymer compound having at least one group or atom selected from the group consisting of a sulfonic acid group, a functional group that can become a sulfonic acid group, and a nitrogen atom. . In particular, a polymer compound containing the above-mentioned functional group or atom in an amount of 0.05 milligram equivalent or atom or more, preferably 0.3 milligram equivalent or atom or more per 1 g of the polymer compound can be suitably used. Although the linear or branched polymer compound used in the present invention is a polymer, it is soluble to some extent in anhydrous hydrofluoric acid, so fluorination proceeds uniformly. Conversely, polymer compounds other than linear or branched polymer compounds, such as those with a three-dimensionally crosslinked structure, can be sufficiently fluorinated even if they have the above-mentioned specific functional groups or atoms. Therefore, it is not preferable as a raw material for the present invention. In addition, some linear or branched polymer compounds having functional groups or non-atomic functional groups specified in the present invention can be highly fluorinated, but at the same time, carbon atoms in the polymer can be highly fluorinated.
It is unsuitable as a raw material for the present invention because the carbon bond chain is broken and a polymeric fluorine-containing compound cannot be obtained efficiently. The linear or branched polymer compound used in the present invention will be explained in detail below. () The above-mentioned polymer compound having a sulfonic acid group can be used without particular limitation, regardless of the bonding position of the sulfonic acid group, as long as the sulfonic acid group is contained in the polymer compound. For example, the sulfonic acid group may be directly or indirectly bonded to a carbon atom, benzene ring, etc. forming a polymer chain. () The above-mentioned polymer compound having a functional group that can become a sulfonic acid group can also be used without being particularly limited as described above. Furthermore, the functional groups that can become sulfonic acid groups are not particularly limited, but representative examples include the following functional groups. That is, -SO ₃ 1/ZM (where M is an alkali metal or alkaline earth metal and Z is the valence of M), -SO ₂ X (where X is a halogen atom), -SO ₃ R (where R is a carbonized Functional groups such as hydrogen residues) are suitable. In particular, the functional group is -
In the _case of _a functional group represented _by SO ₂ The _2F group is most preferred. () The linear or branched polymer compound having a nitrogen atom is not particularly limited as long as the polymer compound has a nitrogen atom bonded thereto. Examples of bonding forms of the nitrogen atom that are generally preferably used include primary amino groups, secondary amino groups, tertiary amino groups including pyridine bases, and quaternary ammonium bases including quaternary pyridium bases. It is bonded as a functional group to a linear or branched polymer compound. The method for producing the linear or branched polymer compound used in the present invention described in () to () above is not particularly limited, but typical methods will be described below. Linear or branched polymer compounds having a sulfonic acid group or a functional group that can become a sulfonic acid group include, for example, styrene sulfonic acid, vinyl sulfonic acid, allyl sulfonic acid, salts derived from these vinyl compounds, and acid halogens. It can be obtained by polymerizing compounds, esters, etc. alone or by copolymerizing them with other monovinyl compounds. Furthermore, the raw material of the present invention can be obtained by treating various linear or branched polymer compounds such as polystyrene with concentrated sulfuric acid, chlorosulfonic acid, etc., and subjecting them to hydrolysis and other post-treatments as necessary. You can also do it. Among these, those in which a sulfonic acid group, an alkylsulfonic acid group, or a functional group capable of forming these groups are directly bonded to a carbon atom forming a polymer chain, such as vinylsulfonic acid, vinylsulfonic acid derivatives such as vinylsulfonyl chloride, allyl Those obtained by polymerizing sulfonic acid, allylsulfonic acid derivatives such as allylsulfonyl chloride alone or copolymerizing them with other monovinyl compounds such as styrene tend to preserve the functional groups during electrolytic fluorination. be. Furthermore, by condensing phenolsulfonic acid, naphtholsulfonic acid, etc. with aldehydes such as formalin, if necessary, together with phenols such as phenol, linear polymer compounds can be obtained by selecting reaction conditions. I can do it. However, the polymer compounds having sulfonic acid groups obtained by such condensation polymerization reactions tend to be inferior in terms of the yield and molecular weight of the desired product compared to those obtained by the above-mentioned polymerization or copolymerization. be. A linear or branched polymer compound having nitrogen atoms bonded thereto can be obtained by polymerizing an alkylimine such as ethyleneimine. Also, 2-
Vinyl pyridine having a basic nitrogen atom such as vinylpyridine derivatives such as vinylpyridine and 2-methyl-5vinylpyridine, vinylpiperidine derivatives represented by 2-vinylpiperidine, and vinylimidazole derivatives represented by 2-vinylbenzimidazole. It can be obtained by polymerizing the compound alone or by copolymerizing it with other monovinyl compounds such as styrene. These nitrogen-containing polymer compounds can be suitably used as raw materials for the present invention even if some or all of the nitrogen atoms are alkylated with an alkylating agent, if necessary. In addition, the linear or branched polymer compound having nitrogen atoms bonded to it is a halogen-containing linear or branched polymer compound, such as a haloalkylated polystyrene, a homopolymer or a copolymer of chloromethylstyrene. It can also be obtained by treating a polymer or the like with dimethylamine or the like. diethylenetriamine, tetraethylenepentamine,
A linear polymer compound can also be obtained by condensing metaphenylenediamine or the like with an aldehyde such as formalin, if necessary, together with a phenol such as phenol, if the reaction conditions are selected. However, the yield of the target product and the molecular weight of the obtained fluorine-containing polymer tend to be inferior to those obtained by the above polymerization or copolymerization. Furthermore, in the present invention, a linear or branched polymer compound having both a sulfonic acid group or a functional group capable of becoming a sulfonic acid group and a nitrogen atom can also be suitably used. Such a polymer compound can be obtained, for example, by copolymerizing a vinyl compound having a sulfonic acid group or a functional group capable of becoming a sulfonic acid group as shown above and a vinyl compound having a basic nitrogen atom. Furthermore, any of the above-mentioned linear or branched polymer compounds in which some of the hydrogen atoms have been replaced with other halogens such as chlorine can also be used as raw materials for the electrolytic fluorination of the present invention. be able to. During electrolytic fluorination, a polymer chain scission reaction occurs to some extent along with the fluorination reaction. Therefore, the molecular weight of the linear or branched polymer compound used is 500 or more, preferably 1000 or more, more preferably 3000 or more, but it may be selected and used as appropriate depending on the molecular weight of the fluorine-containing polymer to be obtained. . In the present invention, anhydrous hydrofluoric acid is used as the electrolytic bath. Pure anhydrous hydrofluoric acid alone does not have electrical conductivity, but when an atomic polymer compound that can be used in the present invention is added thereto, it generally shows some electrical conductivity. However, if the conductivity is insufficient just by adding the raw material polymer compound to anhydrous hydrofluoric acid, it is preferable to add a conductivity increasing agent, and it is usually used at a concentration of 0.1 to 10% by weight. Examples of conductivity increasing agents include those such as amines and ammonia, which are themselves fluorinated and need to be added sequentially as the fluorination reaction progresses during electrolysis, and alkali metals and alkaline earths. Some metal fluorides are simply dissolved in anhydrous hydrofluoric acid. The method of adding the linear or branched polymer compound into the electrolytic bath is not particularly limited. For example, it can be added to the bath in advance before energization, or it can be added continuously or intermittently during electrolysis. Next, the shape of the electrolytic cell used in the present invention is not particularly limited, and may be cylindrical, rectangular columnar, etc.
The material used is metal such as nickel, monel, copper, or iron, or a material that can withstand electrolytic baths such as fluororesin. The cathode and anode in the electrolytic cell are installed substantially vertically in order to facilitate the escape of gas bubbles generated at the electrodes. The material of the anode is limited in terms of conductivity, corrosion resistance, etc., and nickel, nickel alloy (for example, monel), etc. are used. The shape of the anode includes a plate, a net, a round rod shaped like a sag, a perforated plate, an expanded metal, etc. processed into a flat or wavy shape. On the other hand, the material for the cathode is nickel,
It is made of nickel alloy, copper, stainless steel, iron, etc., and its shape is similar to that of the anode. Although it is not usually necessary to install a diaphragm between the cathode and anode in the electrolytic cell, a downwardly open partition plate, a porous plate, or a porous membrane made of a material that can withstand the electrolytic bath may be installed if necessary. Electrolytic conditions such as current density and current flow rate in the electrolytic fluorination of the present invention vary depending on the type, property, amount, etc. of the polymer compound used, or the intended fluorine-containing polymer, and cannot be unconditionally specified. Generally, electrolysis is carried out at a current density of 0.01 to 5 A/dm ² , and although electrolysis is usually carried out at a constant current, it is also possible to change the current value periodically or to change the current value gradually as the electrolysis progresses. It is also possible to perform constant potential electrolysis.
There are no particular restrictions on the temperature, pressure, and whether or not the electrolytic bath is stirred during electrolysis, but generally -20 to +
It is carried out at 30°C, preferably -15 to +15°C. Note that preliminary energization may be appropriately performed in order to remove impurities such as water in the electrolytic bath prior to actual energization. In this case, an electrode for preliminary energization may be provided separately. The fluorine-containing polymer obtained by the electrolytic fluorination of the present invention is liquid or solid and often has almost no solubility in anhydrous hydrofluoric acid. Therefore, the desired electrolyzed product may be extracted from the bottom of the electrolytic cell either continuously during electrolysis or after the electrolysis is completed. Alternatively, after the electrolysis is completed, the anhydrous hydrofluoric acid in the battery can be distilled off by heating the battery to obtain a battery residue. However, the product obtained in this manner contains a fluorine-containing polymer as well as a low molecular weight compound and, in some cases, a raw material polymer compound. Further, the fluorine-containing polymer may have a certain degree of distribution in molecular weight and degree of fluorination.
In such a case, it is also possible to separate and collect a fluorine-containing polymer having a desired molecular weight and degree of fluorination. In this case, a separation method such as recrystallization, distillation, extraction, fractional precipitation, fractional dissolution, etc. may be employed depending on the types of other compounds present. EXAMPLES In order to explain the present invention more specifically, the present invention will be described below with reference to Examples, but the present invention is not limited to these Examples. Example 1 A polymer (molecular weight 23,000) obtained by polymerizing 2-methyl-N-vinylimidazole in methanol using benzoyl peroxide as an initiator was subjected to electrolytic fluorination. The electrolytic cell was made of polychlorotrifluoroethylene and had a capacity of approximately 1000 c.c. shadow,
The anodes were made of three and two nickel plates (height 8
cm x width 5 cm). Anhydrous hydrofluoric acid, which had been sufficiently preliminary electrolyzed in a separate electrolytic bath to remove impurities such as water, was supplied to the electrolytic bath, 10 g of polymer was added, and electrolysis was carried out while stirring the electrolytic bath. The electrolysis temperature was 0°C, and current was applied at 0.45A. After 110 hours, the voltage between the anode and cathode reached a sufficiently large value, so electrolysis was stopped. After removing the anhydrous hydrofluoric acid in the container, the contents are extracted with ethyl ether to form a colorless and transparent viscous liquid (a)5.2
g and 2.1 g of an orange tar-like substance (b) were obtained. The infrared absorption spectrum of both components is 1400−1000 cm ^-1
showed strong absorption based on C-F bonds. The compositions of both components were as shown in Table 1. In addition, the ingredients
The molecular weight of (a) was measured using a molecular weight measuring device based on the vapor pressure equilibrium method (Hitachi Perkin Elmer 115, manufactured by Hitachi, Ltd.) using chloroform as a solvent.
It was hot.

[Table] Example 2 Electrolytic fluorination of 2 g of polymer (molecular weight 5500) obtained by stirring and heating 4-vinylpyridine, carbon tetrachloride and azobisisobutyronitrile in ethylene dichloride Example 1 This was carried out using the electrolytic cell shown in . Electrolysis current value is 0.4A,
The same method as in Example 1 was used except that the current application time was 30 hours. After electrolysis, remove the anhydrous hydrofluoric acid in the container and extract the contents with ethyl ether to obtain 31.5g of fluorine-containing polymer.
Obtained. The molecular weight of this product was approximately 2300, and the results of elemental analysis were as shown in Table 2. Furthermore, poly-4
- 2 g of vinylpyridine which had been quaternized using methyl iodide was subjected to electrolytic fluorination in exactly the same manner. In this case, 2.63 g of a fluorine-containing polymer with a molecular weight of 1800 and a nitrogen and fluorine content of 3.72% and 61.23%, respectively, was obtained.

[Table] Example 3 Electrolytic fluorination was performed using about 2 g of polyethyleneimine (molecular weight 2000) as a sample. Note that polyethyleneimine was commercially available as an aqueous solution and was freeze-dried. Using the electrolytic cell shown in Example 1, the electrolytic current value was 0.5 A, the energization time was 20 hours,
The same method as in Example 1 was used except that the electrolysis temperature was 5°C. After the electrolysis was completed, the anhydrous hydrofluoric acid in the container was removed, and the residue was extracted with ethyl ether to obtain 0.45 g of a liquid having a molecular weight of 1150 as measured by vapor pressure equilibrium method. Furthermore, 1.47 g of a solid with a larger molecular weight was obtained by extracting the ether insoluble matter with methanol. The results of these elemental analyzes are shown in Table 3.

[Table] Example 4 Polystyrene with a molecular weight of about 20,000 was chloromethylated to a degree of 20 in a chloromethylation solution consisting of chloromethyl ether, carbon tetrachloride, and anhydrous tin tetrachloride.
% was chloromethylated. This product was treated separately with ammonia, methylamine, and dimethylamine to obtain linear polymer electrolytes having primary, secondary, and tertiary amino groups, respectively. Three grams each of these were used as samples for fluorination. The method of electrolytic fluorination and the method of separating the fluorine-containing polymer were almost the same as in Example 1. However, the electrolysis current value was 0.7A and the electrolysis time was 20 hours. Table 4 shows the amount, composition, and molecular weight of the fluorine-containing polymer obtained.

[Table] Example 5 Polystyrene with a molecular weight of 40,000 was sulfonated with concentrated sulfuric acid at 95°C for 3 hours using mercury sulfate as a catalyst, and then purified and dried. Sulfone groups were introduced at a ratio of 0.8 per benzene ring. We performed electrolytic fluorination of polystyrene sulfonic acid. The method of electrolytic fluorination was almost the same as in Example 1. However, the amount of sample used was 3g, and the electrolytic current was
The power supply time was 12 hours at 1A. As a result, the solid content of fluorine and sulfur, which is insoluble in water and chloroform, is 53.6% and 2.4%, respectively. 2.8%
0.98 g of solid was obtained. The infrared absorption spectrum has −
Absorption considered to be based on the formation of COF groups was also observed. Example 6 45 using azobisisobutyronitrile as an initiator
Polyvinylsulfonyl fluoride with a molecular weight of about 40,000, obtained by polymerizing vinylsulfonyl fluoride at ℃, was electrolytically fluorinated. The method of electrolytic fluorination and the method of separating the fluorine-containing polymer were almost the same as in Example 1. However, the amount of sample used was 3
g, the electrolytic current was 0.5 A, the electrolytic temperature was -10°C, and the current application time was 10 hours. This results in a molecular weight of 1000 or more and a fluorine content of 41.3.
%, 2.1 g of a polymer with a sulfur content of 14.5% was obtained. Its infrared absorption spectrum showed strong absorption based on C--F bonds at 1400-1000 cm ^-1 , but almost no absorption based on C--H bonds. Similar results were obtained using the same weight of polyvinylsulfonyl chloride in place of polyvinylsulfonyl fluoride. Furthermore, exactly the same experiment was carried out with polyvinylsulfonic acid, its sodium salt and methyl ester. In these cases, electrolytic fluorination produces polymers with a molecular weight of 1000 or more.
1.40-1.55g was obtained, and the fluorine and sulfur contents were 30-35% and 8.4-9.6%, respectively. Example 7 Styrene and 4-vinylpyridine in a molar ratio of 4:1 were copolymerized in benzene using benzoyl peroxide as an initiator, and the resulting copolymer was then treated with concentrated sulfuric acid to form a benzene ring 8. A linear polymer compound having a molecular weight of approximately 10,000 and having both a pyridine base and a sulfonic acid group was obtained. Electrolytic fluorination of 3 g of this product was carried out in substantially the same manner as in Example 1. However, the electrolytic current was 0.35A and the current application time was 45 hours. As a result, 2.3 g of a fluorine-containing polymer was obtained which was soluble in ethyl ether and had a molecular weight of 4300 and a fluorine, nitrogen, and sulfur content of 61.3%, 0.7%, and 0.4%, respectively.

Claims (1)

[Scope of Claims] 1. Having at least one type of group or atom selected from the group consisting of a sulfonic acid group, a functional group that can become a sulfonic acid group, and a nitrogen atom, using anhydrous hydrofluoric acid as an electrolytic bath. 1. A method for producing a fluorine-containing polymer, which comprises electrolytically fluorinating a linear or branched polymer compound. 2 The functional groups that can become sulfonic acid groups are -SO ₃ 1/ZM (where M is an alkali metal or alkaline earth metal, and Z is the valence of M), -SO ₂ X (where X is a halogen atom) ) or -SO ₃ R (where R is a hydrocarbon residue)
Method described. 3 The nitrogen atom is a primary amino group, a secondary amino group,
The method according to claim 1, wherein at least one functional group selected from the group consisting of a tertiary amino group and a quaternary ammonium base is formed.