JP4122963B2 - Method for producing liquid composition - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a liquid composition in which an ion exchange polymer having a sulfonic acid type functional group is dispersed.
[0002]
[Prior art]
Liquid compositions of ion exchange polymers composed of perfluorocarbon polymers having sulfonic acid type functional groups have conventionally been used for the manufacture and repair of ion exchange thin films, the production of thin films containing conductive or insulating particles, and the like in fuel cells. It is used in the production of electrodes including catalyst particles for chemical batteries.
[0003]
Typical examples of such an ion exchange polymer liquid composition include the following. In other words, the general formula _{CF 2 = CF (OCF 2 CFX} ) p -O q - (CF 2) r - (CF 2 CFX) s -SO 2 perfluorocarbon monomer (wherein represented by F, X is fluorine atom or A trifluoromethyl group, p is an integer of 0 to 3, s is an integer of 0 to 3, r is an integer of 0 to 12, and q is 0 or 1, and tetrafluoroethylene, Then, the —SO ₂ F group is converted to —SO ₃ M group (M is a hydrogen atom, a sodium atom or a potassium atom) by hydrolysis or the like, and this is converted into a lower alcohol or a lower alcohol. It is produced by dissolving and dispersing in a solvent containing a lower alcohol such as a mixture of water.
[0004]
Several methods for dissolving and dispersing the ion exchange polymer have been reported. For example, in Patent Document 1, the solid content concentration is 4.3 to 10.4% (the mass ratio of the solid content to the solution. Hereinafter, the mass ratio is indicated unless otherwise noted in terms of the solid content concentration). For 3 to 100 hours. In Patent Document 2, it is dissolved and dispersed by closed mixing at a solid content concentration of 4.3 to 39.4% at 180 to 240 ° C. for 3 to 18 hours. In patent document 3, it melt | dissolves and disperse | distributes for 0.5 to 5 hours at 230-280 degreeC by solid content concentration 7.5-33.1%. In patent document 4, it melt | dissolves and disperse | distributes by stirring and mixing for 16 to 72 hours at 25-60 degreeC by solid content concentration 2%. In Patent Document 5, it is dissolved and dispersed at a solid content concentration of 10%.
[0005]
However, in any case, a high temperature or a long time is required for dissolution / dispersion, and a method for obtaining a uniform liquid composition in a short time at a medium to low temperature of 60 to 160 ° C., which is easy to handle in production, has been reported. There was nothing.
[0006]
[Patent Document 1]
Japanese Examined Patent Publication No. 61-40267 (Example)
[Patent Document 2]
Japanese Examined Patent Publication No. 4-35226 (Example)
[Patent Document 3]
JP-T-2001-504872 (Example)
[Patent Document 4]
JP 2001-81261 A (Example)
[Patent Document 5]
JP 2001-185164 A (Example)
[0007]
[Problems to be solved by the invention]
In recent years, there has been a demand for increasing the strength of membranes, and in order to improve the strength, it has become necessary to dissolve and disperse ion exchange polymers having a large molecular weight or a low ion exchange capacity. In order to obtain a uniform liquid composition using such a polymer, the conventional dissolution / dispersion method requires a longer time.
[0008]
Accordingly, the present invention provides a method for producing a liquid composition in which a highly fluorinated ion exchange polymer having a sulfonic acid type functional group is dissolved and dispersed at a low temperature in a short time in order to solve the above problems. With the goal.
[0009]
[Means for Solving the Problems]
In the present invention, an ion exchange polymer composed of a perfluorocarbon polymer having a —SO ₃ M group (M represents a hydrogen atom, a potassium atom or a sodium atom) is used in an amount of 1 to 10% from a predetermined solid content concentration of 3 to 50 %. After mixing with the first solvent so as to obtain a high solid content concentration and stirring at 60 to 160 ° C. for 1 to 20 hours, the second solvent is added so as to obtain the predetermined solid content concentration, and 1 to 20 is obtained. A liquid composition comprising an ion exchange polymer produced by stirring for a time , wherein the first solvent and the second solvent comprise an alcohol having 1 to 4 carbon atoms or a mixture of the alcohol and water . A manufacturing method is provided.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the second solvent may be added after the ion exchange polymer is mixed with the first solvent and dissolved or dispersed, and then cooled to room temperature and then added, or at 60 to 160 ° C. During the stirring with the first organic solvent, the second organic solvent may be added using a press-fit tube. The latter is preferred for simplifying the process. Even in the former case, it is preferable to stir by heating again to 60 to 160 ° C. after the addition of the second solvent, but the stirring may be performed at room temperature without raising the temperature. Further, after the second solvent is added, a solvent can be further added.
[0011]
Here, the first solvent and the second solvent may be the same or different. Usually, the same solvent is used, and the addition of the second solvent is a step of diluting the liquid composition. The 1st and 2nd solvent here may consist of 1 type of organic solvents, and may be a mixture of 2 or more types of organic solvents. Furthermore, a mixture of an organic solvent and water may be used. Specifically, the following organic solvent, a mixed solvent of two or more of the following organic solvents, or a mixed solvent of one or more of the following solvents and water are preferably exemplified.
[0012]
Lower (C1-C4) alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, n-butyl alcohol, isopropyl alcohol. 2,2,2-trifluoroethanol, 2,2,3,3,3-pentafluoro-1-propanol, 2,2,3,3-tetrafluoro-1-propanol, 2,2,3,4, 4,4-hexafluoro-1-butanol, 2,2,3,3,4,4,4-heptafluoro-1-butanol, 1,1,1,3,3,3-hexafluoro-2-propanol Such as fluorinated alcohols such as perfluorotributylamine, perfluoro-2-n-butyltetrahydrofuran, and other perfluorinated oxygen- or nitrogen-containing compounds, 1,1,2-trichloro-1,2,2-trifluoroethane, etc. Hydrode such as chlorofluorocarbons, 3,3-dichloro-1,1,1,2,2-pentafluoropropane, 1,3-dichloro-1,1,2,2,3-pentafluoropropane Other chlorofluorocarbons, N, N-dimethylformamide and, N, N- dimethylacetamide, dimethyl sulfoxide and the like.
[0013]
Among them, a mixed solvent of alcohol and water having 1 to 4 carbon alcohol or a carbon number of 1 to 4 carbon rather preferable, in the present invention using these solvents.
[0014]
In the present invention, the ion exchange polymer is first stirred at a high solid content concentration to give a high shearing force to the polymer to promote dissolution or dispersion of the ion exchange polymer, and then to a predetermined concentration. A second solvent is added and stirred. Thus, by adding the solvent in two stages, a uniform liquid composition can be obtained in a short time.
[0015]
Here, when mixing a 1st solvent and an ion exchange polymer, it mixes so that it may become 1-10% higher solid content concentration by mass ratio than solid content concentration of the target liquid composition. If it is lower than 1%, a sufficiently high shearing force cannot be imparted to the ion exchange polymer in the initial stirring, and the effect of adding the solvent in two portions is reduced. On the other hand, if the concentration is higher than 10%, the difference in concentration before and after the addition of the second solvent becomes high, so that it takes time to uniformly disperse after the addition. In particular, it is preferably 1 to 5% higher than the solid content concentration of the target liquid composition.
[0016]
The solid content concentration of the finally obtained liquid composition is preferably 3 to 50%, and particularly preferably 5 to 50%. In addition, the liquid composition preferably has an SVI value based on a viscosity at 25 ° C. immediately after the step of adding the second solvent and stirring is 1 to 10, particularly 1 to 5. preferable. In the present specification, the SVI value indicates a ratio μ ₁₀ / μ ₁₀₀ of the viscosity μ _{10 at} a shear rate of 10 s ⁻¹ and the viscosity μ _{100 at 100 s} ⁻¹ . When the SVI value is 1, it is considered that the liquid composition is a Newtonian fluid and is in a uniform dissolved and dispersed state. If the SVI value exceeds 10, the thixotropy is too strong, making it difficult to handle the liquid composition, and it takes time for the SVI value to approach 1.
[0017]
In the present invention, the mixing of the first solvent and the ion exchange polymer is performed at 60 to 160 ° C, and particularly preferably 70 to 120 ° C. If the temperature is too low, the ion exchange polymer cannot be sufficiently dissolved or dispersed in the first solvent. If the temperature is too high, for example, when alcohol is used as the first solvent, ether may be generated. In addition, a heat medium other than warm water is required, and when the temperature is higher than 300 ° C., the polymer is decomposed.
[0018]
The time for stirring and mixing the first solvent and the ion exchange polymer is 1 to 20 hours, and particularly preferably 5 to 15 hours. If this time is too short, the ion exchange polymer cannot be sufficiently dissolved or dispersed. For homogenization of the liquid composition, stirring for a long time is preferable, but too long is not preferable because it takes time for production. Similarly, the time for stirring and mixing after adding the second solvent is 1 to 20 hours, and 5 to 15 hours is particularly preferable. If this time is too short, the ion exchange polymer cannot be sufficiently dissolved or dispersed. On the other hand, if it is too long, the time required for production becomes long.
[0019]
The ion-exchange polymer in the present invention is a perfluorocarbon polymer having a —SO ₃ M group (M is a hydrogen atom, a sodium atom, or a potassium atom). May contain oxygen atoms and the like. As the ion exchange polymer, the general formula _{CF 2 = CF (OCF 2 CFX} ) p -O q - and (CF 2 _CFX) s polymerized units based on perfluorocarbon represented by _{-SO 3 M - (CF 2)} r Copolymers containing polymerized units based on tetrafluoroethylene are preferred. Here, X is a fluorine atom or a trifluoromethyl group, p is an integer of 0 to 3, s is an integer of 0 to 3, r is an integer of 0 to 12, and q is 0 or 1. is there. The copolymer is, for example _{CF 2 = CF (OCF 2 CFX} ) p -O q - (CF 2) r - (CF 2 CFX) After synthesizing the copolymer of s -SO ₂ F and tetrafluoroethylene It can be obtained by substituting —SO ₂ F group with —SO ₃ M group by hydrolysis or the like.
[0020]
The ion exchange capacity of the ion exchange polymer in the present invention is preferably 0.5 to 4.0 meq / g dry resin. For example, when used for production of an electrode containing catalyst particles for an electrochemical cell such as a fuel cell, it is preferable to use a polymer having a high ion exchange capacity in order to increase the gas permeability and control the voltage increase. When the ion exchange capacity exceeds 4.0, a problem arises in mechanical strength. Moreover, it is preferable to have an ion exchange capacity of at least 0.5 or more from the viewpoint of ion permeability. From the same viewpoint, the ion exchange capacity is more preferably 0.7 to 2.0.
[0021]
The ion exchange polymer in the present invention is preferably _{T Q} is 100 to 300 ° C., in particular 150 to 270 ° C. are preferred. T _Q is a number which becomes a measure of the molecular weight, but who T _Q high polymer is high mechanical strength, too high and the molding is difficult. The polymer T _Q is too low causes problems in the mechanical strength. In the present specification, “T _Q ” of a polymer refers to a temperature indicating a volume flow rate of 100 mm ³ / second related to the molecular weight of the polymer. Here, the capacity flow rate was expressed by the unit of mm ³ / sec, where the polymer was melted and flowed out from an orifice having a diameter of 1 mm and a length of 2 mm held at a constant temperature under a pressure of 3 MPa. Is. In general, the higher the _TQ , the higher the molecular weight, and the lower the _TQ , the lower the molecular weight.
[0022]
In the present invention, the step of mixing the ion exchange polymer with the first organic solvent and the second organic solvent and dissolving or dispersing the ion exchange polymer is preferably performed using a stirring and mixing tank. Since the solution is expected to reach a high viscosity of about several mPa · s to several tens of thousands mPa · s, it is preferable to use a stirring blade for high viscosity, such as a helical ribbon blade, a screw blade, a double helical ribbon blade, or the like. . However, ordinary mixing turbine blades, anchor blades, paddle blades, and the like can also be used.
[0023]
The uniformity of the liquid composition obtained by the method of the present invention can be evaluated by measuring the viscosity. Specifically, for example, the viscosity of the liquid composition may be measured using an E-type viscometer at a shear rate of 10 to 1000 s ⁻¹ at 25 ° C., and a state where the viscosity does not change with time may be made uniform. The liquid composition according to the present invention does not necessarily become a uniform state immediately after production, but becomes uniform when left at 5 to 35 ° C. It becomes uniform in a short standing time as compared with a liquid composition obtained by a conventional method.
[0024]
【Example】
[Example 1 (Example)]
680 g of C ₈ F ₁₇ C ₂ H ₅ , 0.8 g of azobisisobutyronitrile, and 922 g of CF ₂ ═CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ SO ₂ F were charged into a 2-liter stainless steel autoclave. After sufficiently degassing with liquid nitrogen, the temperature was set to 70 ° C., tetrafluoroethylene was introduced, and the pressure was adjusted to 1.1 MPa as a gauge pressure. Tetrafluoroethylene was successively added so that the pressure was constant during the polymerization. After 8 hours, unreacted tetrafluoroethylene was purged to terminate the polymerization, and the resulting polymer solution was agglomerated with methanol, washed and dried to obtain 180 g of a copolymer. The measured T _Q of the copolymer was 230 ° C..
[0025]
Next, after converting -SO 2 _F groups to -SO 3 _K groups hydrolyzed by mixing with heating the copolymer at KOH aqueous solution containing methanol, washed with water, under aqueous sulfuric acid By mixing, it was further converted into —SO ₃ H group to obtain a —SO ₃ H type copolymer. The ion exchange capacity of the obtained copolymer was 1.1 meq / g dry resin.
[0026]
Using a stainless steel autoclave with an internal volume of 2 L, 150 g of the -SO ₃ H type copolymer and 1154 g of ethanol are added, and dissolution and dispersion are performed at 80 ° C. and 100 rpm for 5 hours using a helical ribbon blade. Carried out. The solid content concentration at this time was 11.5%. Once cooled to room temperature, 275 g of ethanol was added. After the additional addition, the mixture was stirred at 100 rpm at room temperature for 15 hours, while mixing was performed at 100 rpm for 2 hours at 80 ° C. The solid content concentration at this time was 9.5%.
[0027]
After extracting a small amount of the obtained liquid, the viscosity was measured at 25 ° C. with an E-type viscometer. SVI value is 200mPa · s 800mPa · s, at a shear rate of 100s ^-1 at shear rate ^{10s -1} was 4. This solution was stored at room temperature of 20 ° C. Was measured again viscosity after one week, SVI value is 80mPa · s 100mPa · s, at a shear rate of 100s ^-1 at shear rate ^{10s -1} was 1.25. When the viscosity was measured again two weeks after the production, it was 70 mPa · s at a shear rate of 10 s ⁻¹ , 70 mPa · s at a shear rate of 100 s ⁻¹ , and the SVI value was 1. From this result, it was confirmed that the liquid composition was homogenized one week after production.
[0028]
[Example 2 (comparative example)]
In the same manner as in Example 1, 150 g of —SO ₃ H type resin was dissolved in 1429 g of ethanol using a helical ribbon blade and dissolved and dispersed at 80 ° C. and 100 rpm for 5 hours, then cooled to room temperature, and 15 rpm at 100 rpm. Stir with. The solid content concentration at this time was 9.5%.
[0029]
After extracting a small amount of the obtained liquid, the viscosity was measured at 25 ° C. with an E-type viscometer. SVI value is 200mPa · s 2000mPa · s, at a shear rate of 100s ^-1 at shear rate ^{10s -1} was 10. This solution was stored at room temperature of 20 ° C. Was measured again viscosity after one week, SVI value is 150mPa · s 750mPa · s, at a shear rate of 100s ^-1 at shear rate ^{10s -1} was 5. Also was measured again viscosity two weeks after manufacture, SVI value is 80mPa · s 100mPa · s, at a shear rate of 100s ^-1 at shear rate ^{10s -1} was 1.25. The liquid composition was not homogenized one week after manufacture and required two weeks to reach the same viscosity as Example 1.
[0030]
【The invention's effect】
According to the production method of the present invention, a liquid composition in which an ion exchange polymer composed of a perfluorocarbon polymer having a —SO ₃ M group is uniformly dissolved or dispersed can be easily produced at a low temperature in a short time.

Claims (3)

An ion exchange polymer composed of a perfluorocarbon polymer having a —SO ₃ M group (M represents a hydrogen atom, a potassium atom or a sodium atom) is 1 to 10% higher in mass ratio than the predetermined solid content concentration of 3 to 50%. After mixing with the first solvent to obtain a solid content concentration and stirring at 60 to 160 ° C. for 1 to 20 hours, the second solvent is added to obtain the predetermined solid content concentration, and 1 to 20 hours. A liquid composition comprising an ion exchange polymer , wherein the first solvent and the second solvent are made of an alcohol having 1 to 4 carbon atoms or a mixture of the alcohol and water . Production method. The method for producing a liquid composition according to claim 1, wherein the liquid composition is stirred at 60 to 160 ° C. after adding the second solvent. Said liquid composition, the liquid according to claim 1 or 2 SVI value based on the viscosity at 25 ° C. immediately after completion of the step of stirring by adding the second solvent is produced to an 1-10 A method for producing the composition.