JPH0357578B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for sealing an electrode base material for a fuel cell, and more particularly to a method for filling an electrode base material sealing paste.

[Conventional technology]

Fuel cells are widely known as being used in power generation systems that replace thermal power generation. An electrochemical cell such as a fuel cell is constructed by laminating a large number of electrodes, and if even one of the electrodes is defective, the operation of the entire cell will be affected. Therefore, in the electrode manufacturing process, it is necessary to be able to produce a large number of good products.

FIG. 7 is a sectional view showing the electrode structure of a phosphoric acid fuel cell. In the figure, 1 is an air electrode, and 2 is a fuel electrode, and in this case, the air electrode 1 and the air electrode 2 are shown separated. The air electrode 1 has an electrode base material, e.g.
Carbon paper 3 with a thickness of about 600 μm and 50
It consists of a catalyst layer 4 of about 200 μm and a packing 5 made of fluorocarbon rubber.

Also, the fuel electrode 2 is carbon paper 3, 30 ~
A catalyst layer 8 with a thickness of approximately 150 μm, a wet seal portion 6 that has undergone sealing treatment, a peripheral gas seal portion 7, and
It consists of a matrix layer 9 of about 150 μm.
Note that the matrix layer 9 may be formed as an independent film.

In the case of the fuel electrode 2, the electrode manufacturing process includes an ignition process for the carbon paper 3, a sealing process for the wet seal section 6, a coating process for the catalyst layer 8, a coating process for the peripheral gas seal section 7, and a matrix layer coating process. There are 5 steps of 9 coating steps.
The wet seal portion 6 and the peripheral gas seal portion 7 of the fuel electrode 2 also play an important role as a route for replenishing phosphoric acid from the phosphoric acid replenishment mechanism (external reservoir) provided at the bottom of the wet seal portion 6 to the matrix layer 9. ing.

Wet seal part 6 during the electrode manufacturing process.
In the sealing process, carbon paper is filled with fine powder such as silicon carbide as a sealing paste.The filled fine powder of silicon carbide retains phosphoric acid and is used as a wet seal. fulfill one's role. Therefore, unless the fine powder is filled into the carbon paper as densely as possible, sufficient bubble pressure for sealing cannot be maintained. In addition, there is a high possibility that the reaction gas will leak between the rough surface of the wet seal section 6 and the opposing gas separation plate. It is necessary that the surface be as smooth as possible.

Conventionally, a spray method has been used to fill carbon paper, which is an electrode base material, with fine powder such as silicon carbide.

The spray method is a method in which fine powder such as silicon carbide is made into a paste by adding water and a thickener, and the paste is sprayed onto carbon paper like a mist to penetrate and fill the paste.

[Problem that the invention seeks to solve]

The conventional method for sealing a fuel cell electrode base material as described above has the following problems. First, after spraying the paste onto the carbon paper, the paste is allowed to penetrate naturally, which makes it difficult to sufficiently fill the paste deep into the carbon paper, and the filling rate is low. Second, it is difficult to form a wet seal part 6 with a smooth surface. Third, a mask must be placed on the part 3 to be treated with water to distinguish it from the part 3 of the carbon paper to be treated with water. However, for this reason,
More paste adheres to the mask, lowering the paste utilization rate.

This invention was made in order to solve these problems, and it is possible to increase the filling rate of paste into the electrode base material, form a seal with a smooth surface, and further reduce the waste of paste for fuel. The purpose of this invention is to obtain a sealing treatment method for battery electrode base materials.

[Means for solving problems]

The method for sealing an electrode base material for a fuel cell according to the present invention holds the electrode base material between a stage and a printer mask, supplies a sealing paste from a replacement fluid holder to an opening provided in the printer mask, and then applies a squeegee to the sealing paste. and a step of filling the sealing paste filled in the opening into the electrode base using a roller. This is what I did.

[Effect]

In this invention, the sealing paste is dropped into the mask opening by the replacement fluid holder, thereby reducing the amount of paste that adheres to the mask. The squeegee and roller also serve to push the paste filled into the mask openings into the electrode base material.

〔Example〕

Common filling methods include the natural roll coater method and the printing method. This natural roll coater method does not allow sufficient filling in one filling, and has disadvantages such as difficulty in positioning and repeating it several times.On the other hand, when filling with a rubber squeegee using the printing method, the amount of filling is sufficient. However, there were problems such as the sealing paste tending to remain on the surface of the sealing part. The seal processing method according to the present invention is a method that combines a printing method and a roller method, and is intended to improve both the filling rate of the paste and the surface condition after seal processing.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of an apparatus according to the method of sealing a fuel cell electrode base material of the present invention, and FIG. 2 is a plan view of this apparatus. In the figure, 10 is an electrode base material, for example carbon paper, 11 is a printer mask, 12 is a stage that holds the electrode base material 10 between the printer mask 11, 13 is a first squeegee holder, and 14 is a first squeegee holder. 13 is a first rubber squeegee made of, for example, a rubber material; 15 is a paste replenishment fluid holder; 16 is a fluid volume adjustment screw provided in the replenishment fluid holder 15; 17 is a triangular pyramidal valve; and 18 is a replenishment fluid holder 15. 19 is a second squeegee holder, 20 is a second rubber squeegee,
21 is a roller holder, and 22 is a roller provided on the roller holder 21 and made of, for example, a rubber material.

The first squeegee 14, second squeegee 20, and roller 22 are movable up and down, and the first and second squeegee 14, 20, fluid replacement holder 16, and roller 22 are configured to be movable as a whole in the direction of the arrow in the figure. has been done. Seal processing paste is in fluid holder 1
A triangular pyramid-shaped valve 17 is moved up and down by a liquid volume adjusting screw 16, and the amount of paste dripping can be adjusted by adjusting the size of the opening 18. Further, the replenishment fluid holder 16 is refilled with paste from an external paste tank (not shown) through a silicone tube (not shown) using a roller pump (not shown). Furthermore, 23 is the axis of the roller 22;
24 is a mask opening of the printer mask 11. Note that the mask 11 is, for example, a meshless metal mask (made of aluminum);
For example, the external size is 1500 x 1500 mm and the thickness is 600 μm. The sealing paste is filled into the opening 24 of the printer mask 11. Further, the paste is dropped between the first squeegee and the second squeegee. In addition, in FIG. 1 and FIG. 2, the vertical movement of the squeegees 14, 20 and the roller 22,
The mechanism for left and right movement is omitted.

Next, a series of operations for sealing the opening 24 by this device will be described. 3A to 3D are explanatory diagrams showing the sealing method using the squeegees 14, 20 and the roller 22 in the order of steps, and unnecessary parts such as a fluid replacement device are omitted. FIG. 3a shows the middle of the outward journey, with the first squeegee 14 descending, the second squeegee 20, and the roller 22 rising, moving downward in the figure. In this step, the paste is supplied to the mask opening 24 by the replacement fluid holder, and is embedded in the mask opening 24 by the first squeegee 14. FIG. 3b shows the state where the space surrounded by the mask opening 24 and the electrode base material 10 has been filled with paste, and at this time, the paste is applied to the upper part of the electrode base material by the thickness of the mask (approximately
600 μm). Next, on the return trip, the first squeegee 14 goes up, the second squeegee 20 and the roller 22 go down, and move upward in the figure as shown in FIG. 3c. In this step, the excess paste filled in the opening 24 is removed with the second squeegee 20, and the mask opening 24 is further removed.
4 and the electrode base material 10 are more reliably filled with the paste. Subsequently, the paste filled in the mask openings 24 is pushed into the electrode base material 10 by the rollers 22 . FIG. 3d shows the state where the roller 22 has finished filling the electrode base material with the paste. If the filling of the paste is insufficient, the operations shown in FIGS. 3a to 3d are repeated.

FIG. 4 is an enlarged front sectional view of the roller portion. In order to fill the inside of the electrode base material 10 with the paste filled in the mask opening 24 and to prevent the paste from protruding outside the mask opening 24, the rubber of the roller 22 must be inserted into the mask opening 24.
must be closely adhered to. For this reason, roller 2
Various rubber materials such as silicone rubber, urethane rubber, and neoprene rubber were tried for the second rubber, and various rubber hardnesses were also prototyped and examined. As a result, a sponge-like urethane rubber with a hardness of about 20° to 30° was found to be most suitable for the mask opening 2.
4, and the filling inside the electrode base material 10 was also sufficient.

FIG. 5 is an enlarged cross-sectional view of the roller portion viewed from the side, showing how the mask opening 24 is filled with paste by the second squeegee 20,
The figure shows how the electrode base material 10 is filled with paste by the roller 22.

Further, in this device, the stage 12 is configured to be movable. That is, initially, the stage 12 is in a position parallel to the mask 11, and the electrode base material 10 is fixed on the stage 12. Next stage 12
slides to the bottom of the mask 11, rises, and holds the electrode base material 10 between the mask 11 and the stage 12 as shown in FIG. The electrode base material 10 can be fixed on the stage 12 by, for example, pasting a magnetic plate for drafting on the entire surface of the stage 12, and placing a strip-shaped thin iron plate on the part of the electrode base material 10 that is not to be sealed to absorb the magnetic force. Thus, the electrode base material 10 was fixed.

Further, the positioning of the electrode base material 10 is performed using the stage 12.
Various lines indicating the position of the sealing process were drawn on the magnetic plate attached to the surface of the magnet, and these lines were used as a guideline, and the positional deviation due to the sealing process was within 1 mm.

In addition, in this device, all operations, such as the movement of the stage 12, the vertical movement of the first and second stages 14 and 20, and the vertical movement of the roller 22, are controlled by a computer, and the speed and number of filling operations are controlled by a computer. You can arbitrarily decide whether to repeat or not, and perform a series of actions with a single button. In practice, using this device, it took less than 1 minute for each electrode base material to be set and removed after sealing.

The amount of sealing paste to be filled is determined by the thickness and porosity of the electrode base material, and the actual amount to be filled is determined by the thickness of the mask, the solid content of the paste, the number of times of filling, etc. In the case of a 0.4 mm electrode base material, filling by moving back and forth twice was sufficient to fully fill the back surface with the paste.

In addition, the weight of the filled area was measured after drying, and the filling rate of the paste was compared with that of the conventional spray method.As a result, the method according to the present invention produced approximately twice the paste weight compared to the spray method. It becomes the filling amount. Further, according to observation using a microscope, the surface of the sealed portion became extremely smooth.
Furthermore, the sample sealed using the filling method according to the present invention and the sample processed using the spray method,
In order to investigate the functionality as a wet seal, we infiltrated the sample with phosphoric acid and examined the bubble pressure and the amount of gas leakage.The results showed that the sample according to the present invention was superior in both cases, especially in terms of the amount of gas leakage. This seems to be because the sealing paste was sufficiently filled in the filling method of the present invention, and the surface of the sealing area was smoothed.

In addition, to change the pattern of the seal processing area, just change the pattern of the opening of the print mask.
You can freely choose any pattern. Further, even when the electrode base material 10 is thick like a ribbed electrode base material, according to the sealing method of the present invention, it is only necessary to increase the number of reciprocating movements for filling, and the sealing paste can be sufficiently filled. I can do it.

For reference, another application of the seal processing method according to the present invention is the formation of an internal reservoir in a ribbed electrode base material. The internal reservoir is filled with hydrophilic fine particles such as silicon carbide locally in the electrode base material in the same way as filling with sealing paste, but in this case, the pattern of the internal reservoir is changed as shown in Figure 6. Using the provided mask, the internal reservoir can be formed in the same manner as in the sealing process.

〔Effect of the invention〕

As explained above, this invention holds an electrode base material between a stage and a printer mask, supplies a sealing paste from a replenishing fluid holder to an opening provided in the printer mask, and uses the stage to connect the electrode base material and the opening. The filling rate of the sealing paste can be increased by performing a process of filling the space surrounded by the opening and a process of filling the electrode base material with the sealing paste filled in the opening using a roller. The sealing treatment surface can be smoothed. Furthermore, there is an effect that a method for sealing a fuel cell electrode base material with less waste of paste can be obtained.

[Brief explanation of drawings]

1 and 2 are a sectional view and a plan view, respectively, showing a seal processing apparatus according to an embodiment of the present invention, and FIGS. 3 a to 3 d are explanatory diagrams showing a method according to an embodiment of the present invention in order of steps, 4 and 5 are a front sectional view and a side sectional view respectively showing an enlarged roller portion of a seal processing device according to an embodiment of the present invention, and FIG. FIG. 7 is a plan view showing a reference example when such a seal processing device is used for other purposes, and FIG. 7 is a cross-sectional view showing the electrode configuration of a fuel cell. 10... Electrode base material, 11... Printer mask, 1
2...Stage, 14, 20...Squeegee, 15...Replacement fluid holder, 22...Roller, 24...Printer mask opening. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. An electrode base material is held between a stage and a printer mask, a sealing paste is supplied from a fluid replacement holder to an opening provided in the printer mask, and a squeegee is used to separate the electrode base material and the A fuel cell electrode base material comprising a step of filling a space surrounded by an opening, and a step of filling the electrode base material with the sealing paste filled in the opening using a roller. Seal processing method. 2. The electrode base material for a fuel cell according to claim 1, wherein a pair of squeegees is provided, a fluid replacement holder is provided between both squeegees, and a roller is provided on the opposite side of the fluid replacement holder to one of the squeegees. Seal treatment method. 3. One squeegee is in contact with the printer mask on the outward trip and fills the opening of the printer mask with the sealing paste, and the other squeegee is in contact with the printer mask on the return trip and fills the opening with the sealing paste, The roller contacts the printer mask on the return trip,
3. The method of sealing an electrode base material for a fuel cell according to claim 2, wherein the sealing paste is filled into the electrode base material.