JP6295940B2 - Method for producing catalyst ink - Google Patents

Description

  The present invention relates to a method for producing a catalyst ink.

  Conventionally, there has been proposed a method of preparing a catalyst ink having a desired viscosity by stirring and mixing a catalyst dispersion and a gel (see Patent Documents 1 and 2). In this method, the viscosity of the catalyst ink can be changed by adjusting the amount of stirring.

International Publication No. WO2013 / 31060 JP 2014-192070 A

  In the conventional technique, it is considered that the longer the stirring time is, the finer the gel body is decomposed and the dispersibility of the gel body is improved. It was found that the gel body did not become finer. This is because the fine gel body floats in the solution (catalyst ink) even if it continues to rotate at a constant rotation speed, and only with the ink and drifts along the inner wall of the container. This is probably because it cannot be added to the gel body. In addition, even if it stirs for a certain time or more, it is the knowledge discovered for the first time by the inventor of the present invention that the gel body does not become finer.

  If the gel body cannot be made fine, the dispersibility of the gel body in the catalyst ink is poor. As a result, when the catalyst ink was used for coating, there was a problem that the coated surface was cracked.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.
One embodiment of the present invention is a method for producing a catalyst ink used for forming a catalyst electrode. The method for producing the catalyst ink includes: (a) preparing a catalyst dispersion prepared by dispersing catalyst-carrying particles, which are conductive particles carrying a catalyst, in a solvent; and (b) an ionomer and a solvent. You may provide the process of preparing the gel body produced by mixing, and the process of (c) mixing the said catalyst dispersion liquid and the said gel body by stirring, and creating a catalyst ink. In the step (c), after stirring at a predetermined stirring speed for a predetermined period, stirring may be further performed so that the stirring speed is further decreased and increased. According to this method for producing a catalyst ink, sufficient shearing force can be applied again to the gel body that has become fine to some extent by stirring for a predetermined period of time by stirring with a decrease and increase in stirring speed. Thus, the gel body can be made fine and the dispersibility of the gel body in the mixed solution can be improved. For this reason, when using a catalyst ink for coating, the crack of a coating surface can be suppressed.
Another embodiment of the present invention is a method for producing a catalyst ink used for forming a catalyst electrode. The method for producing the catalyst ink includes: (a) preparing a catalyst dispersion prepared by dispersing catalyst-carrying particles, which are conductive particles carrying a catalyst, in a solvent; and (b) an ionomer and a solvent. You may provide the process of preparing the gel body produced by mixing, and the process of (c) mixing the said catalyst dispersion liquid and the said gel body by stirring, and creating a catalyst ink. In the step (c), the stirring may be performed by communicating the inside of the container in which the stirring is performed with a communication pipe to the outside air. According to this method for producing a catalyst ink, the pressure in the container is released to the outside, so that the convection of the mixed solution is not hindered. For this reason, a gel body can be made fine and the dispersibility to the mixed solution of a gel body can be improved. Therefore, when the catalyst ink is used for coating, it is possible to suppress cracking of the coating surface.
In addition, the present invention can be realized as the following forms.

(1) One embodiment of the present invention is a method for producing a catalyst ink used for forming a catalyst electrode. The method for producing the catalyst ink includes: (a) preparing a catalyst dispersion prepared by dispersing catalyst-carrying particles, which are conductive particles carrying a catalyst, in a solvent; and (b) an ionomer and a solvent. You may provide the process of preparing the gel body produced by mixing, and the process of (c) mixing the said catalyst dispersion liquid and the said gel body by stirring, and creating a catalyst ink. In the step (c), the stirring may be performed so that the stirring speed after stirring for a predetermined period changes with a decrease and an increase. According to this method for producing a catalyst ink, sufficient shearing force can be applied again to the gel body that has become fine to some extent by stirring for a predetermined period of time by stirring with a decrease and increase in stirring speed. Thus, the gel body can be made fine and the dispersibility of the gel body in the mixed solution can be improved. For this reason, when using a catalyst ink for coating, the crack of a coating surface can be suppressed.

(2) In the manufacturing method of the catalyst ink of the said form, you may perform the said stirring using a disper blade. According to this method for producing a catalyst ink, the shear force by stirring can be improved by using the disper blade.

(3) In the method for producing the catalyst ink of the above aspect, the reduction in the stirring speed may stop the stirring. According to this method for producing catalyst ink, by stopping stirring, the gel body biased near the inner wall of the container by stirring for a predetermined period before stopping can be reliably diffused toward the inside of the container. As a result, the dispersibility of the gel body in the mixed solution can be further improved.

(4) In the method for producing the catalyst ink of the above aspect, in the step (c), the stirring may be performed by communicating the inside of the container for stirring with outside air. At the time of stirring, the mixed solution is pressurized due to volatilization of the solvent, which may hinder convection of the mixed solution. However, according to this catalyst ink manufacturing method, the pressure in the container is Therefore, convection is not hindered. For this reason, a gel body can be fully mixed with a solution and a gel body can be made finer.

(5) Another embodiment of the present invention is a method for producing a catalyst ink used for forming a catalyst electrode. The method for producing the catalyst ink includes: (a) preparing a catalyst dispersion prepared by dispersing catalyst-carrying particles, which are conductive particles carrying a catalyst, in a solvent; and (b) an ionomer and a solvent. You may provide the process of preparing the gel body produced by mixing, and the process of (c) mixing the said catalyst dispersion liquid and the said gel body by stirring, and creating a catalyst ink. In the step (c), the stirring may be performed by communicating the inside of the container for stirring with outside air. According to this method for producing a catalyst ink, the pressure in the container is released to the outside, so that the convection of the mixed solution is not hindered. For this reason, a gel body can be made fine and the dispersibility to the mixed solution of a gel body can be improved. Therefore, when the catalyst ink is used for coating, it is possible to suppress cracking of the coating surface.

  The present invention can be realized in various forms other than the method for producing the catalyst ink. For example, it can be realized in the form of a method for manufacturing a membrane electrode assembly including each step in the method for manufacturing catalyst ink, a method for manufacturing a fuel cell, or the like.

It is process drawing which shows the manufacturing process of the catalyst ink as one Embodiment of this invention. It is the schematic which shows the structure of the stirring apparatus used at the process 3. FIG. It is explanatory drawing which shows a stirring blade. It is a flowchart which shows the rotational speed control process of the stirring blade performed by the controller. It is a timing chart which shows the time change of the rotational speed of the stirring blade realized by the rotational speed control process. It is explanatory drawing which shows the convection of the mixed solution in a container. It is explanatory drawing which shows an experimental result in a table | surface. It is a timing chart which shows the time change of the rotation speed of the stirring blade realized by rotation speed control processing in a 2nd embodiment. 10 is a timing chart of Modification 3. It is the schematic which shows the structure of the stirring apparatus used in the modification 6. FIG. 10 is a schematic diagram illustrating a configuration of a stirring device used in Modification 7.

Next, an embodiment of the present invention will be described.
A. First embodiment:
A-1. Overall structure of catalyst ink manufacturing process:
FIG. 1 is a process diagram showing a production process of a catalyst ink as one embodiment of the present invention. The catalyst ink is for forming a catalyst electrode in a membrane electrode assembly used in a solid polymer fuel cell. As shown in the figure, the catalyst ink manufacturing process is composed of three processes from process 1 to process 3. Each process 1-3 is demonstrated in order.

[Step 1]
In step 1, a catalyst dispersion is prepared by dispersing catalyst-carrying particles in a solvent. Specifically, first, catalyst-carrying particles in which a catalyst is carried on conductive particles, for example, platinum-carrying carbon is prepared, and a dispersed aqueous solution is prepared by mixing the catalyst-carrying particles and water (for example, ion-exchanged water). . Thereafter, an alcohol (for example, ethanol) is added to the aqueous dispersion. Here, the catalyst-carrying particles and water are mixed first, and the catalyst-carrying particles are immersed in water, whereby ignition when alcohol is added can be suppressed.

  Next, an ionomer solution containing the same kind of ionomer as used in Step 2 is added to the solvent liquid in which the catalyst-carrying particles and alcohol are mixed. An ionomer is an electrolyte having proton conductivity (for example, a fluorine-based resin). In addition, you may comprise with hydrocarbon resin, for example, without restricting to fluorine resin. This ionomer functions as a surfactant for promoting dispersion of the catalyst-carrying particles.

  After adding the ionomer solution, the mixed solution in which the catalyst-supporting particles, alcohol, and ionomer are mixed is stirred using an ultrasonic disperser or the like. In Step 1, the ionomer solution may be added to the dispersed aqueous solution of catalyst-carrying particles before the alcohol is added.

[Step 2]
Step 2 is a step of creating a gel body by mixing an ionomer and a volatile solvent. Specifically, a gel solution having a predetermined viscoelasticity is prepared by preparing a mixed solution in which an ionomer and a volatile solvent are mixed, subjecting the mixed solution to a thickening treatment, and increasing the viscosity. In this embodiment, an alcohol solution is used as the volatile solvent, and heat treatment is performed as the thickening treatment. The heat treatment can be performed by an evaporator or an autoclave. In addition, the process 1 and the process 2 do not necessarily need to be performed in order of the process 1 and the process 2, and may be performed in the order of the process 2 and the process 1. Moreover, you may perform the process 1 and the process 2 simultaneously.

[Step 3]
Step 3 is a step of obtaining a catalyst ink having a desired viscosity by mixing the catalyst dispersion obtained in Step 1 and the gel obtained in Step 2 by stirring. Step 3 will be described in detail later. The manufacturing process of the catalyst ink is completed by the above-described steps 1 to 3.

A-2. Stirring device configuration:
FIG. 2 is a schematic diagram showing the configuration of the stirring device used in step 3. The stirring device 10 includes a container 20, a stirring unit 40, and a controller 50. The container 20 includes a bottomed cylindrical container body 22 having an open top, and a lid body 24 that covers the top of the container body 22. In the present embodiment, the lid body 24 is provided with a communication pipe 26 for communicating the inside of the container body 22 with the outside air (atmosphere).

  The stirring unit 40 includes a stirring blade 42, a rotating shaft 44, and a drive motor 46.

  FIG. 3 is an explanatory view showing the stirring blade 42. As shown in the drawing, the stirring blade 42 is a so-called disper blade in which a plurality of edges 42b and 42c protruding alternately upward and downward are formed on the outer periphery of a disk-shaped member 42a. The stirring blade 42 includes a projecting hole 42d to which the rotation shaft 44 is attached at the center of a disk-shaped member 42a.

  As shown in FIG. 2, the stirring blade 42 having the above-described configuration is suspended from a drive motor 46 via a rotation shaft 44 so that it can rotate at a high speed in the center of the container body 22. The rotation shaft 44 is disposed along the central axis of the bottomed cylindrical shape of the container body 22. A controller 50 is connected to the drive motor 46.

  The controller 50 is a microcomputer including a CPU, a ROM, a RAM, and the like, and controls the rotation speed of the stirring blade 42 by controlling the operation of the drive motor 46. The “rotation speed” is the number of rotations per predetermined time. The rotation speed is controlled by the CPU executing a process according to a program stored in advance in the ROM.

  In Step 3 of FIG. 1, first, the catalyst dispersion liquid obtained in Step 1 and the gel body obtained in Step 2 are supplied into the container 20 of the stirring device 10. Then, the controller 50 causes the mixed solution MF of the catalyst dispersion liquid and the gel body to be stirred to rotate and flow by rotating the stirring blade 42 at a high speed. As a result, the mixed solution MF rotates and flows while receiving pressure toward the side surface of the container body 22 by the centrifugal force generated by the high-speed rotation of the stirring blade 42 and is stirred. As a result, the catalyst dispersion and the gel body are mixed.

  Formation of the catalyst electrode in the membrane electrode assembly is performed by intermittently applying catalyst ink so that an expensive platinum catalyst is not applied to a useless portion that does not contribute to power generation. In order to suppress sagging of the ink-like catalyst that becomes a problem due to intermittent coating, it is necessary to control the viscosity of the catalyst ink.

  In the present embodiment, as described above, a catalyst dispersion liquid as a catalyst ink is created in Step 1, and a gel body in which an ionomer is gelled is created separately in Step 2. Then, Step 3 is performed in order to add and disperse the required amount of the gel formed in Step 2 to the catalyst dispersion prepared in Step 1. Thereby, the viscosity of the catalyst ink can be controlled. Here, the inventor of the present invention may not be able to sufficiently disperse the gel body in the catalyst dispersion only by rotating the stirring blade 42 at a constant rotational speed. It was found that the gel body can be sufficiently dispersed in the catalyst dispersion liquid by controlling the rotation speed so as to change with a decrease and increase after the rotation for a predetermined period. Specifically, in this embodiment, in step 3, the rotation speed control process of the stirring blade described later is performed.

A-3. Composition of the stirring blade rotation speed control process:
FIG. 4 is a flowchart showing the stirring blade rotation speed control process executed by the controller 50. The rotation speed control process is started at a predetermined timing after the catalyst dispersion liquid and the gel body are supplied into the container 20 of the stirring device 10 in Step 3. When the process is started, the controller 50 first controls the drive motor 46 to rotate the stirring blade 42 at the rotation speed Va (step S110). The rotation speed Va is, for example, 1500 [rpm].

  Next, the controller 50 determines whether or not a predetermined time Ta has elapsed after the start of the rotation speed control process (step S120). The predetermined time Ta is, for example, 75 [min]. Here, if it is determined that the predetermined time Ta has not elapsed, it waits for the predetermined time Ta to elapse. During this time, the stirring blade 42 rotates at a constant rotation speed Va. If it is determined in step S120 that the predetermined time Ta has elapsed, the controller 50 controls the drive motor 46 to stop the stirring blade 42 (step S130).

  The rotational speed Va in step S110 and the predetermined time Ta in step S120 are taken into consideration that the gel body contained in the mixed solution MF existing in the container 20 becomes somewhat small (for example, 50 to 30 [μm]). is there. The rotation speed Va is preferably, for example, 1000 [rpm] or more, and in the present embodiment, as described above, the rotation speed Va is set to 1500 [rpm]. The predetermined time Ta is preferably 60 to 200 [min], for example, and is set to 75 [min] in the present embodiment as described above.

  Subsequently, the controller 50 determines whether or not a predetermined time Tb has elapsed after stopping the stirring blade 42 in Step S130 (Step S140). The predetermined time Tb is, for example, 0.5 to 5 [min], and is 1 [min] in the present embodiment. Here, if it is determined that the predetermined time Tb has not elapsed, the process waits for the predetermined time Tb to elapse. If it is determined in step S140 that the predetermined time Tb has elapsed, the controller 50 controls the drive motor 46 to rotate the stirring blade 42 again (step S150). In the present embodiment, the rotational speed for re-rotation is the same rotational speed Va as in step S110.

  Subsequently, the controller 50 determines whether or not the predetermined time Tc has elapsed after the re-rotation in Step S150 (Step S160). The predetermined time Tc is, for example, 10 to 20 [min], and in this embodiment, 15 [min]. If it is determined that the predetermined time Tc has not elapsed, the process waits for the predetermined time Tc to elapse. During this time, the stirring blade 42 rotates at a constant rotation speed Va. If it is determined in step S160 that the predetermined time Tc has elapsed, the controller 50 advances the process to step S170.

  In step S170, the controller 50 determines whether or not the number of re-rotations in step S150 is a predetermined number n or more. The predetermined number n is a value 2, for example. If it is determined that the number of re-rotations is less than the predetermined number n, the controller 50 returns the process to step S130 and repeatedly executes the processes of steps S130 to S160. The predetermined number n may be other numbers such as value 1, value 3, value 4,..., Value 10, value 20, etc., instead of the value 2 described above.

  On the other hand, if it is determined in step S170 that the number of re-rotations is equal to or greater than the predetermined number n, the controller 50 controls the drive motor 46 to stop the stirring blade 42 (step S180). Thereafter, the process returns to “return”, and the rotation speed control process of the stirring blade is finished. As a result, step 3 in FIG. 1 is completed, and the manufacturing process of the catalyst ink is completed. The catalyst ink produced as described above is directly applied to the electrolyte membrane by, for example, a die coating method or a spray method to form a catalyst electrode.

  In the step 3 configured as described above, the inside of the container 20 is communicated with the outside air by the communication pipe 26 provided in the lid body 24 and agitation is performed.

  FIG. 5 is a timing chart showing temporal changes in the rotational speed V of the stirring blade 42 realized by the rotational speed control process of FIG. As shown in the drawing, the rotational speed V of the stirring blade 42 becomes Va at time t0, and the rotational speed V maintains Va from time t0 to time t1 after a predetermined time Ta. At time t1, the stirring blade 42 stops and the rotational speed V becomes zero. From time t1 to time t2 after a predetermined time Tb, the rotation speed V continues to be 0. At time t2, the rotation speed V becomes Va, and the rotation speed V maintains Va from time t2 to time t3 after a predetermined time Tc. At time t3, the stirring blade 42 stops and the rotation speed V becomes zero.

  After time t3, the time change from time t1 to time t3 is repeated a predetermined number of times n-1. That is, in this embodiment, it is repeated only once. Specifically, the rotational speed V continues to be 0 from time t3 to time t4 after a predetermined time Tb. At time t4, the rotational speed V becomes Va, and the rotational speed V maintains Va from time t4 to time t5 after a predetermined time Tc. At time t5, the stirring blade 42 stops and the rotation speed V becomes zero. Thereafter, the catalyst ink manufacturing process is completed.

  According to the timing chart, since the time axis of the horizontal axis is a large scale of minutes, it can be read that the stirring blade is stopped and the return to the rotation speed Va is realized instantaneously. At the time of stop, the rotation speed gradually decreases, the rotation speed falls to 0 for a certain time, and when returning to the rotation speed Va, the rotation speed gradually increases to reach the rotation speed Va for a certain time. It will fit.

A-4. Effects of the embodiment:
As described above in detail, according to the manufacturing process of the catalyst ink in the present embodiment, in the step 3 of stirring and mixing the catalyst dispersion and the gel body, the predetermined time Ta and the stirring blade 42 are set at a constant rotational speed Va. By rotating, the gel body can be made fine to some extent. Thereafter, by stopping the stirring blade 42 and stirring it with re-rotation, it becomes possible to apply sufficient shearing force again to the gel body that cannot receive sufficient shearing force by continuous stirring. Thereby, the gel body can be made fine and the dispersibility of the gel body in the mixed solution MF can be improved. For this reason, when using a catalyst ink for coating, the crack of a coating surface can be suppressed.

  Moreover, according to the manufacturing process of the catalyst ink in this embodiment, the shear force by stirring can be improved by making the stirring blade 42 which performs stirring into the disper blade.

  Furthermore, according to the catalyst ink manufacturing process of the present embodiment, the inside of the container 20 is communicated with the outside air by the communication pipe 26 provided in the lid body 24 in the step 3 of stirring and mixing the catalyst dispersion and the gel body. Therefore, the following problems can be solved. In the stirring method using shearing force, the energy of stirring is dissipated to the surroundings as heat. It is known that a lower alcohol often used in a fuel cell is vaporized even at a temperature not reaching a boiling point of 30 to 40 ° C. At this time, if the container of the stirring device is completely sealed, convection of the mixed solution in the container may be hindered.

  FIG. 6 is an explanatory diagram showing convection of the mixed solution in the container. Convection occurs as indicated by the arrows in the figure. If the container 20 is completely sealed, this convection will be hindered. According to the manufacturing process of the catalyst ink in the present embodiment, in the step 3 of stirring and mixing, the container 20 is communicated with the outside air by the communication pipe 26 provided in the lid body 24, and thus stirring is performed. Since the internal pressure is released to the outside, the convection is not hindered. For this reason, a gel body can be fully mixed with a solution and a gel body can be made finer.

A-5. About the experimental example:
In a 300 mL beaker, a catalyst dispersion obtained by weighing catalyst, ionomer, ethanol, and water is dispersed using an ultrasonic homogenizer to reduce the catalyst to a desired size. When the dispersed catalyst dispersion was measured with a particle size distribution meter, the particle size at D50 was 5.1 μm. The “particle size at D50” means a particle size in which the integrated value of the weight of particles having a particle size equal to or smaller than the particle size occupies 50% of the total weight of the particles. On the other hand, the gel was gelled by heating. The elastic modulus of the gel was 274 Pa at 1% strain as measured by a viscoelasticity measuring device. A certain amount of gel was weighed into the catalyst dispersion prepared as described above to prepare an experimental gel ink. In order to determine that the gel body was refined, it was determined that the gel body became completely fine when the elastic modulus of the gel ink was less than 10 Pa using a viscoelasticity measuring device.

  FIG. 7 is an explanatory diagram showing experimental results in a table. In Experiments AC, a 32 mm diameter disper blade was used as the stirring blade. The stirring rotation speed was 2300 rpm. In Experiment A, the stirring blade was stopped every 10 minutes from the start of stirring, the gel ink was sampled, the stirring blade was rotated again, and rotated at a constant speed. The result of measuring the viscoelasticity of the sampled gel ink is the value in the table. From the results of Experiment A, it can be seen that the gel ink had a modulus of elasticity of 9.75 Pa after 75 minutes of stirring, and the gel was sufficiently fine in the ink.

  In Experiment B, the gel ink was sampled by continuously rotating from the start of stirring until 75 minutes, and then the stirring blade was stopped every 15 minutes, the gel ink was sampled, the stirring blade was rotated again, and rotated at a constant speed. I let you. From the result of Experiment B, it can be seen that the gel ink has a modulus of elasticity of 50 Pa when it is continuously stirred for 75 minutes, and it cannot be said that the gel body has become sufficiently fine in the ink. Thereafter, when stop and re-rotation are repeated every 15 minutes, it can be seen that in 105 minutes, the elastic modulus of the gel ink becomes 10 Pa, and the gel body becomes sufficiently fine in the ink.

  In Experiment C, the gel ink was sampled by continuously rotating from the start of stirring to 105 minutes, and then the stirring blade was stopped every 15 minutes, the gel ink was sampled, the stirring blade was rotated again, and rotated at a constant speed. I let you. From the result of Experiment C, it can be seen that the gel ink has an elastic modulus of 34 Pa at the time of continuous stirring for 105 minutes, and it cannot be said that the gel body has become sufficiently fine in the ink. Thereafter, when stop and re-rotation are repeated every 15 minutes, it can be seen that after 135 minutes, the elastic modulus of the gel ink is 7 Pa, and the gel body is sufficiently fine in the ink.

  From Experiments B and C, it was found that the gel body was reduced to about 30 to 50 Pa by continuous stirring, but it was difficult to reduce it further by continuous stirring alone. This is because a gel body that has become fine to a certain degree floats in the mixed solution even if it continues to rotate at a constant rotational speed, and it is carried around with the solution and drifts along the inner wall of the container. This is thought to be because it cannot be added to the body. In addition, even if it stirs for a certain time or more, it is the knowledge discovered for the first time by the inventor of the present invention that the gel body does not become finer.

  On the other hand, as in Experiment A, it was proved effective to stop and restart stirring after continuous stirring. This is because the gel body provided by continuous stirring diffuses inward from the vicinity of the inner wall of the container by the stop, and is then rotated again, so that the shear force can be received again from the stirring blade. This is probably because of this. The present invention is born from the knowledge obtained by these experiments.

B. Second embodiment:
FIG. 8 is a timing chart showing temporal changes in the rotational speed of the stirring blades realized by the rotational speed control process in the second embodiment. In the method for producing the catalyst ink in the second embodiment, compared to the method for producing the catalyst ink in the first embodiment, the step S130 (FIG. 4) for stopping the stirring blade is rotated at the initial constant speed. The difference is that the structure is reduced to a rotational speed Vb (> 0) lower than the rotational speed Va at that time. Other configurations in the second embodiment are the same as those in the first embodiment. As a result, as shown in FIG. 8, in the period from time t1 to time t2 and in the period from time t3 to time t4, the rotation speed of the stirring blade is switched to a rotation speed Vb lower than the rotation speed Va. After this period, the rotational speed Va is restored.

  Also by the method for producing the catalyst ink in the second embodiment configured as described above, after the stirring blade is rotated at the constant rotation speed Va for a predetermined time Ta, the rotation speed is decreased and changed with an increase. By stirring the gel body, the gel body biased near the inner wall of the container by continuous stirring can be diffused toward the inside of the container. Thus, similarly to the first embodiment, the gel body can be made sufficiently fine to improve the dispersibility of the gel body in the mixed solution MF, and when the catalyst ink is used for coating, Cracking can be suppressed.

C. Variations:
・ Modification 1:
In the first embodiment, the reduction of the stirring speed is realized by stopping the rotation of the stirring blade, and in the second embodiment, the rotation speed is switched to a rotational speed Vb (> 0) that is lower than the rotational speed Va of the stirring blade before the reduction. However, instead of these, it may be realized by switching the rotation of the stirring blades in the reverse direction, that is, by switching the rotation speed to a-(minus) value. Further, when the rotational speed is changed, the rotational speed may be gradually decreased or increased by gradually changing the control value for the drive motor.

Modification 2
In the first and second embodiments, the rotation speed of the stirring blade is constant during a predetermined period from the start of stirring. However, the rotation speed is not necessarily constant, and the rotation speed may be varied. In short, any configuration may be used as long as stirring is performed for a predetermined period before stirring that changes with a decrease and increase in the stirring speed.

・ Modification 3:
In the first and second embodiments, the rotational speed at which the stirring blades are stopped and then re-rotated is the same as the rotational speed Va when rotating at the first constant speed, but instead, the rotational speed Va It is good also as a different rotational speed. That is, as shown in FIG. 9, the rotation speed Vc may be smaller than the rotation speed Va. Moreover, it is good also as a rotational speed larger than the rotational speed Va. Moreover, as shown in FIG. 9, it is good also as a structure from which the rotational speed at the time of the 1st restart is different from the rotational speed at the time of the 2nd restart.

-Modification 4:
In the first and second embodiments, the disperse blades are used as the stirring blades. However, other types of blades such as helical blades, anchor blades, and pitched turbine blades may be used instead. Since the helical blade and the anchor blade have a smaller shearing force than the disper blade, a blade having a large shearing force such as a disper blade or a pitched turbine blade is preferable.

-Modification 5:
In the first and second embodiments, the number of communication pipes 26 provided on the lid 24 of the container 20 is one, but a plurality of communication pipes may be used instead. In the first and second embodiments, the communication pipe 26 is a simple cylinder communicating with the outside. Instead, a pressure sensor is provided in the container, and when the pressure becomes high, the ventilation device It is good also as a structure which can take in air | atmosphere actively.

Modification 6:
In the first and second embodiments, as shown in FIG. 10, a rectangular thin plate 110 may be erected on the inner side surface of the container body 22. In this modified example 6, the width of the thin plate 110, that is, the distance Db protruding inward, is 50% to 10%, for example, 30% of the distance Da from the inner side surface to the stirring blade 42. According to this configuration, the mixed solution MF that is rotationally flowed by the stirring blade 42 hits the thin plate 110, thereby generating a turbulent flow during stirring. For this reason, a gel body can be mixed more fully and a gel body can be made finer.

Modification 7:
In the first and second embodiments, the rotating shaft 44 that connects the stirring blades 42 is disposed along the central axis of the bottomed cylindrical shape of the container body 22. Instead, the rotating shaft 44 is shown in FIG. As described above, the rotation shaft 44, the stirring blade 42, and the drive motor 46 may be arranged so as to be shifted by a predetermined distance E from the center axis Ca. Cb in the figure is the central axis of the rotating shaft 44, and the predetermined distance E is the distance between the central axis Ca and the central axis Cb. In the modified example 7, the predetermined distance E is 20% or less, for example, 15% of the diameter of the disk-shaped member 42a of the stirring blade 42. According to this configuration, more turbulent flow during stirring can be generated as compared with the first embodiment in which the rotation shaft 44 is disposed along the central axis Ca. For this reason, a gel body can be mixed more fully and a gel body can be made finer. In addition, in the structure of this modification 7, it is good also as a structure to which the thin plate 110 of the modification 6 is added.

-Modification 8:
In the first and second embodiments, the process for producing the catalyst ink is performed in steps 1 to 3, but instead, after step 3, the stirring blade is rotated at a constant rotational speed to perform stirring. It is good also as a structure which adds the process 4 (not shown) which performs. In step 4, high-speed rotation is performed at a rotation speed larger than that in step 3. According to this step 4, the centrifugal force generated by the high speed rotation of the stirring blade is used to apply a force toward the side of the container to the mixed solution of the catalyst dispersion and the gel body, By stirring in a state of being attached to the side surface in the form of a thin film, the fluid flows and stirs while receiving pressure toward the side surface of the container body. According to this modified example 8, the catalyst can be more sufficiently adhered to the gel body refined in the step 3 by the step 4.

  The present invention is not limited to the above-described embodiments and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments and the modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the effects, replacement or combination can be performed as appropriate. Moreover, elements other than the elements described in the independent claims among the constituent elements in the above-described embodiments and modifications are additional elements and can be omitted as appropriate.

DESCRIPTION OF SYMBOLS 10 ... Agitation apparatus 20 ... Container 22 ... Container main body 24 ... Lid body 26 ... Communication pipe 40 ... Agitation part 42 ... Agitation blade 42a ... Disc shaped member 42b, 42c ... Edge 42d ... Projection hole 44 ... Rotating shaft 46 ... Drive motor 50 ... Controller MF ... Mixed solution

Claims (5)

A method for producing a catalyst ink used for forming a catalyst electrode,
(A) preparing a catalyst dispersion prepared by dispersing catalyst-carrying particles, which are conductive particles carrying a catalyst, in a solvent;
(B) preparing a gel body prepared by mixing an ionomer and a solvent;
(C) mixing the catalyst dispersion and the gel body by stirring to create a catalyst ink;
With
The step (c)
Predetermined period, the mixture was stirred at a predetermined stirring speed, further stirring rate makes a stirred increase with a decrease in Migihitsuji Ban, process for preparing a catalyst ink. It is a manufacturing method of the catalyst ink of Claim 1, Comprising:
A method for producing a catalyst ink, wherein the stirring is performed using a disper blade. A method for producing the catalyst ink according to claim 1 or 2,
The reduction in the stirring speed is caused by stopping the stirring. It is a manufacturing method of the catalyst ink as described in any one of Claim 1- Claim 3, Comprising:
The step (c)
A method for producing a catalyst ink, wherein the stirring is performed by communicating the inside of the container for stirring with outside air. A method for producing a catalyst ink used for forming a catalyst electrode,
(A) preparing a catalyst dispersion prepared by dispersing catalyst-carrying particles, which are conductive particles carrying a catalyst, in a solvent;
(B) preparing a gel body prepared by mixing an ionomer and a solvent;
(C) mixing the catalyst dispersion and the gel body by stirring to create a catalyst ink;
With
The step (c)
A method for producing a catalyst ink, wherein the stirring is performed by communicating the inside of a container for stirring with outside air through a communication pipe .

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