JP6973241B2 - Continuous manufacturing method of membrane electrode gas diffusion layer bonded body - Google Patents

Description

The present invention relates to a method for continuously producing a membrane electrode gas diffusion layer bonded body.

As a basic form, the fuel cell has a form in which a membrane electrode gas diffusion layer junction (MEGA: Membrane Electrode and Gas diffusion Assembly) is sandwiched under pressure by a separator provided with a gas flow path. As shown in FIG. 6, the membrane electrode gas diffusion layer junction 8 has an electrolyte membrane 1, a cathode catalyst layer 2 in contact with one surface of the electrolyte membrane 1, and an anode catalyst layer in contact with the other surface of the electrolyte membrane 1. A gas diffusion layer 4 on the cathode side is laminated on the surface of the cathode catalyst layer 2 opposite to the electrolyte film 1 side, and an anode is provided on the surface of the anode catalyst layer 3 opposite to the electrolyte film 1 side. A configuration in which the gas diffusion layers 5 on the side are laminated is provided as a basic configuration. The cathode electrode 6 is formed by the cathode catalyst layer 2 and the gas diffusion layer 4 on the cathode side, and the anode electrode 7 is formed by the anode catalyst layer 3 and the gas diffusion layer 5 on the anode side.

The membrane electrode gas diffusion layer junction 8 is sandwiched between a cathode side separator 22 provided with an oxidant (air) gas flow path 21 and an anode side separator 32 provided with a fuel (hydrogen) gas flow path 31 and pressurized. By fastening, it becomes one fuel cell 100.

In manufacturing the membrane electrode gas diffusion layer junction 8, a rectangular catalyst layer and a gas diffusion layer pre-cut to a predetermined size are sequentially laminated on both sides of the electrolyte membrane 1 in a rectangular shape pre-cut to a predetermined size. On the long electrolyte film, for example, as described in Patent Document 1, the catalyst layer wound in a roll shape and the gas diffusion layer wound in a roll shape are unwound while being unwound. A continuous manufacturing method is adopted in which the catalyst layer and the gas diffusion layer are continuously laminated. After the production, the elongated laminated body is cut to a predetermined size to obtain the membrane electrode gas diffusion layer bonded body 8 having the form shown in FIG.

When the membrane electrode gas diffusion layer bonded body is manufactured by the continuous manufacturing method, as a preliminary step, a step of manufacturing a long catalyst layer and a long gas diffusion layer, respectively, and winding them in a roll shape is performed. Will be.

At that time, for the purpose of stabilizing entrainment, a long catalyst layer or a long gas diffusion layer is usually laminated on a long auxiliary material that functions as a release sheet, and the stacking thereof is performed. I try to roll my body around. Then, in the step of unwinding the catalyst layer or the gas diffusion layer from the entrainment roll and laminating it on the continuously moving long electrolyte film, the catalyst layer and the gas diffusion layer are subordinate to each other. It is separated from the material, and only the catalyst layer and the gas diffusion layer are transferred onto the electrolyte membrane and laminated.

As the gas diffusion layer, for example, as described in Patent Document 2, a porous body such as carbon paper or carbon woven fabric is used as a base material, and a solvent is added to the conductive material powder or the water-repellent material. It is generally made by applying a paste (hereinafter referred to as a diffusion layer paste) formed by uniformly kneading and then removing the solvent component in a drying furnace.

Japanese Unexamined Patent Publication No. 2009-38040 Japanese Unexamined Patent Publication No. 2008-71691

As described above, the long gas diffusion layer is formed by applying the diffusion layer paste to carbon paper or carbon woven fabric, which is a porous body as a base material, and then removing the solvent in a drying furnace. NS. Then, as described above, the formed long gas diffusion layer is formed into a laminated body with an appropriate long auxiliary material, is wound into a roll, and is stored as a gas diffusion layer roll.

When the winding tension is increased when the laminate is rolled into a roll, a mesh spreads on the carbon paper or carbon woven fabric, which is a porous body as a base material, and the solvent is released from the enlarged mesh. The removed solvent paste may fall, so-called strike-through. Therefore, there is a limit to the strength of the tension at the time of winding, and it is usually in a loosely wound state.

On the other hand, in the step of unwinding the gas diffusion layer from the laminate of the gas diffusion layer and the auxiliary material wound in the roll and laminating the unwound gas diffusion layer on the catalyst layer, the gas diffusion layer is wound up to the laminated portion. It is required to unwind from the roll with a relatively higher tension so that the resulting gas diffusion layer does not meander and cause inconveniences such as misalignment and breakage.

The present inventors have gained a lot of experience in the continuous production of a membrane electrode gas diffusion layer bonded body, and in the process, from the roll of the laminated body of the gas diffusion layer loosely involved and the auxiliary material, the present inventors have gained a lot of experience. We have experienced that the winding roll is displaced in the axial direction when the gas diffusion layer is unwound with a winding tension larger than the winding tension. If the unwinding is continued in a state where such a misalignment occurs, the misalignment of the gas diffusion layer may occur at the laminated position with the catalyst layer. Therefore, the unwinding tension at the time of unwinding is large. In addition, it is required to pay sufficient attention.

The present invention has been made in view of the above circumstances experienced by the present inventors, and includes a long catalyst layer wound in a roll and a long gas diffusion layer wound in a roll. In a method for continuously manufacturing a membrane electrode gas diffusion layer bonded body, which includes at least a step of laminating on a long electrolyte membrane while unwinding the gas from each roll, the gas diffusion layer unwound from the roll at the time of unwinding is A method for continuously manufacturing a membrane electrode gas diffusion layer bonded body that eliminates the positional deviation of the roll in the axial direction and thereby enables the two to be laminated without any positional deviation when laminated with the catalyst layer. The challenge is to provide.

In order to solve the above-mentioned problems, the present inventors further conducted experiments and research, and found that the above-mentioned axial misalignment has a small tension at the time of entrainment in the entrainment roll of the gas diffusion layer. Therefore, when unwound with a higher tension, a winding phenomenon occurs between the upper layer and the lower layer of the laminated body of the entrained gas diffusion layer and the auxiliary material in the roll, which is caused by this. I learned that there is an axial misalignment. Further, the auxiliary material for the gas diffusion layer currently generally used is a paper sheet having a coefficient of static friction of about 0.5, and a sheet having a coefficient of static friction of about 0.5 is unwound with a large unwinding tension. I also experienced the inability to prevent axial slippage. The present invention is based on the above findings obtained by the present inventors.

That is, in the method for continuously producing a membrane electrode gas diffusion layer bonded body according to the present invention, a long catalyst layer wound in a roll shape and a long gas diffusion layer wound in a roll shape are wound from each roll. It is a continuous manufacturing method of a membrane electrode gas diffusion layer bonded body including at least a step of laminating on a long electrolyte film while taking out, and the long gas diffusion layer is a long auxiliary material. The auxiliary material and the gas diffusion layer are separated from each other at the time of unwinding from the roll, and only the separated gas diffusion layer is sent out to the laminating step. The width of the auxiliary material is wider than the width of the gas diffusion layer, and the static friction coefficient of the auxiliary material is 1.2 or more.

According to the present invention, even if the laminated body is unwound from the winding roll of the laminated body of the gas diffusion layer and the auxiliary material with a winding tension larger than the tension at the time of winding, the static friction coefficient is 1 as the auxiliary material. By using materials of .2 or more, it is possible to suppress slippage between the auxiliary materials, and as a result, it is possible to prevent the laminated body from being displaced in the roll in the axial direction. As a result, the axial misalignment of the unwound gas diffusion layer can be suppressed, and in the continuously manufactured film electrode gas diffusion layer junction, the width misalignment between the catalyst layer and the gas diffusion layer can be suppressed. Can be obtained, and a high-performance film electrode gas diffusion layer junction can be obtained.

The figure for demonstrating the process of manufacturing the laminated body of the long-shaped gas diffusion layer wound in the shape of a roll, and the long-shaped auxiliary material. The figure for explaining the auxiliary material. Top view and sectional view showing an example of a laminated body of an auxiliary material and a gas diffusion layer. Schematic cross-sectional view showing a state in which a laminated body of an auxiliary material and a gas diffusion layer is rolled up in a roll shape. The figure for demonstrating an example of the manufacturing apparatus of a membrane electrode gas diffusion layer bonded body. Schematic cross-sectional view showing a membrane electrode gas diffusion layer junction and a fuel cell.

Hereinafter, an embodiment of a method for continuously manufacturing a membrane electrode gas diffusion layer bonded body according to the present invention will be described with reference to the drawings.

First, with reference to FIG. 1, a process of manufacturing a laminate of a long gas diffusion layer wound in a roll shape and a long auxiliary material will be described. In FIG. 1, reference numeral 41 denotes a base material of a long gas diffusion layer such as carbon paper or carbon woven cloth, for example, having a width of about 100 to 500 mm and a length of about 100 to 500 mm. The base material 41 is unwound from a roll (not shown). The hopper 42 contains a conventionally known diffusion layer paste 43, which is formed by uniformly kneading a conductive material powder or a water-repellent material with a solvent. The diffusion layer paste 43 is applied from the hopper 42 onto the base material 41. The base material 41 coated with the diffusion layer paste 43 passes through the drying oven 45. The solvent component is removed in the drying furnace 45 to form a long gas diffusion layer 40. Then, the gas diffusion layer 40 is wound by the reel 57 in a state of being laminated with the long auxiliary material 50 as a release sheet separately supplied, and the laminated body of the gas diffusion layer 40 and the auxiliary material 50. The roll 56 of 55 is used.

As described above, if the take-up tension on the reel 57 is too large, the mesh of the base material 41 will be wide open, and the conductive material powder or the water-repellent material may fall off from the base material 41. Therefore, the take-up tension on the reel 57 is small, for example, 20 to 40 N. Here, let the take-up tension be A.

The auxiliary material 50 is selected from high friction materials having a static friction coefficient of 1.2 or more. Examples of such materials include natural rubber, butyl rubber, styrene butadiene rubber, and the like. It is desirable that the width of the auxiliary material 50 is about 10% wider than the width of the base material 41. It is desirable that the length is about the same as that of the base material 41.

FIG. 2 is a cross-sectional view of the auxiliary material 50 in the lateral direction. Here, the auxiliary material 50 includes a flat base portion 51, left and right wall portions 52, 52 rising from both side edges of the base portion 51, and an upper surface of the base portion 51 and an inner wall of the left and right wall portions 52, 52. A recess 53 is formed. The distance d between the left and right wall portions 52, 52 is equal to or slightly wider than the width of the gas diffusion layer 40 described above. Further, the heights of the left and right wall portions 52, 52 are substantially equal to or slightly larger than the thickness of the gas diffusion layer 40 (usually about several μm).

FIG. 3 is a plan view (FIG. 3A) of the laminated body 55 of the gas diffusion layer 40 and the auxiliary material 50 in a state of being wound around the reel 57, and a sectional view in the lateral direction (FIG. 3B). ). As shown in FIG. 3, in the laminated body 55, the gas diffusion layer 40 is inserted into the recess 53 partitioned by the base 51 of the auxiliary material 50 and the left and right wall portions 52, 52.

FIG. 4 shows a part of a cross section of the reel 57 in the axial direction of the winding roll 56 in a state where the laminated body 55 is wound by the reel 57. In FIG. 4, 55a is a lower laminated body 55 that is involved, and 55b is a laminated body 55 located above the lower laminated body 55. As shown in FIG. 4, in the lower laminated body 55a and the upper laminated body 55b, the top surfaces of the left and right wall portions 52 and 52 formed on the auxiliary material 50 constituting the lower laminated body 55a are the upper laminated body. Since the auxiliary material 50 is in contact with the back surface of the base 51 of the auxiliary material 50 constituting the body 55b and the coefficient of static friction of the auxiliary material 50 is 1.2 or more, a large frictional force acts between the two. There is.

FIG. 5 shows an example of a method for continuously manufacturing a long film electrode gas diffusion layer bonded body 80 by using a winding roll 56 in which a laminated body 55 of a gas diffusion layer 40 and an auxiliary material 50 is wound. Is shown. In this example, the separately manufactured long catalyst layer 20 and the long gas diffusion layer 40 described above are integrally laminated by passing between the pressure welding rolls 61 and 61, and have a long shape. The cathode electrode 60 (or the anode electrode 70) is laminated on the long electrolyte film 10 transported at a predetermined speed, whereby the long film electrode gas diffusion layer junction body is formed. It is said to be 80.

In addition, in FIG. 5, the cathode electrode 60 (or the anode electrode 70) is laminated only on one surface of the elongated electrolyte film 10, but in reality, the cathode electrode 60 (or the anode electrode 70) is also laminated on the other surface at the same time or in a later step. In the same manner, the anode electrodes 70 (or cathode electrodes 60) are laminated to form a long film electrode gas diffusion layer bonded body 80. Then, the long-shaped membrane electrode gas diffusion layer junction 80 is cut into a required shape, and the like, the membrane electrode gas diffusion layer junction 8 described with reference to FIG. 6 is obtained.

In the production, the entrainment roll 56 is set in the equipment, and the gas diffusion layer 40 and the auxiliary material 50 are separated from the laminated body 55 of the gas diffusion layer 40 and the auxiliary material 50. The separated auxiliary material 50 is wound on a reel (not shown) and reused as needed. Only the separated gas diffusion layer 40 is guided between the pressure welding rolls 61 and 61 through the guide roll, and is integrally laminated with the elongated catalyst layer 20 as described above.

The tension related to the gas diffusion layer 40 at that time, that is, the unwinding tension B, depends on the rotation speed and joining pressure of the pressure welding rolls 61 and 61, but from the separation from the auxiliary material 50 to the space between the pressure welding rolls 61 and 61. In order to avoid blurring and meandering in the gas diffusion layer 40, the unwinding tension B is usually set to the take-up tension A (for example, 20) related to the gas diffusion layer 40 when the winding roll 56 is manufactured. It is larger than ~ 40N), for example, 45-80N.

As described with reference to FIG. 4, in the roll 56, the lower laminated body 55a and the upper laminated body 55b are left and right wall portions 52, 52 formed on the auxiliary material 50 constituting the lower laminated body 55a. The top surface of the auxiliary material 50 and the back surface of the base 51 of the auxiliary material 50 constituting the upper laminated body 55b are in direct contact with each other, and the coefficient of static friction of the auxiliary material 50 is 1.2 or more. Has a large frictional force.

Therefore, even if a large unwinding tension B (> A) acts on the gas diffusion layer 40 by pulling out (unwinding) the gas diffusion layer 40 by the pressure welding rolls 61, 61, the stack is wound as the entrainment roll 56. It is possible to prevent the winding tightening phenomenon from occurring on the body 55, and it is possible to suppress the occurrence of slippage between the upper and lower auxiliary materials 50 and 50. As a result, it is possible to effectively eliminate the axial displacement of the unwound gas diffusion layer 40 by the time it reaches the pressure contact rolls 61 and 61.

In the embodiment shown in FIG. 5, the long catalyst layer 20 and the long gas diffusion layer 40 are integrally laminated when passing between the pressure contact rolls 61 and 61. However, a long catalyst layer 20 is laminated on the long electrolyte film 10, and the long member has a long catalyst layer 20 on the long member. It is also possible to stack the scale-shaped gas diffusion layer 40. In that case, only the long gas diffusion layer 40 passes between the pressure welding rolls 61 and the drive rolls corresponding to the 61.

Further, as the auxiliary material 50 that functions as a release sheet, a material in which a recess 53 is formed is exemplified as shown in FIG. 2, but the thickness of the gas diffusion layer 40 is usually several μm, and the auxiliary material 50 is used. If the width of the material 50 is set wider, the required frictional force described above can be obtained without positively providing the recess 53. In either case, if the area ratio of the gas diffusion layer 40 to the auxiliary material 50 is 90% or less, the intended purpose can be achieved. Further, when a material such as natural rubber, butyl rubber, or styrene-butadiene rubber is used as the auxiliary material 50 which is a high friction material, it can be reused because wrinkles and the like do not remain after peeling, unlike the paper material. ..

As described above, when the winding roll 56 of the laminated body 55 composed of the gas diffusion layer 40 and the auxiliary material 50 is tightened, the laminated body 55 is displaced in the axial direction due to the winding tightness, and the laminated body 55 is unwound. The gas diffusion layer 40 is displaced. When such a misalignment occurs, it is necessary to stop the equipment for continuously manufacturing the membrane electrode gas diffusion layer junction and readjust it. Therefore, the rate of equipment outages due to winding tightening during production was verified using Examples and Comparative Examples.

The materials of the catalyst layer 20 and the gas diffusion layer 40 used for the verification are the same in both the examples and the comparative examples, and the material of the catalyst layer is a generally used platinum-supported carbon + fluorine-based electrolyte membrane. The material of the gas diffusion layer used was a generally used carbon paper + diffusion layer paste.

As the auxiliary material 50, the one having the shape shown in FIG. 2 was used. In the examples, three types of high friction materials, natural rubber, butyl rubber, and styrene-butadiene rubber, were used as the auxiliary material 50. In the comparative example, a paper film, which is a low friction material, was used as the auxiliary material 50.

Using the equipment of the form shown in FIG. 5, a laminated body (electrode) 60 of the catalyst layer 20 and the gas diffusion layer 40 was produced. In the experiment, the transport speed between the catalyst layer and the gas diffusion layer was 1 to 10 m / min, the take-up tension of the diffusion layer was 20 to 40 N, the unwinding tension was 45 to 80 N, and the bonding temperature between the catalyst layer and the gas diffusion layer was 100. A plurality of laminates (electrodes) 60 were manufactured while changing the bonding pressure between 2 and 6 kN at ~ 150 ° C. Then, we examined the rate at which the equipment had to be shut down due to the tightening that occurred during production. The results are shown in Table 1 together with the coefficient of static friction of the auxiliary materials.

[Discussion]
As shown in Table 1, when a low friction material (paper film) with a static friction coefficient of 0.5 was used as an auxiliary material, the ratio of having to stop the equipment during production was 50%. Met. On the other hand, when a high friction material having a coefficient of static friction of 1.2 or more was used as the auxiliary material, there was no inconvenience that the equipment had to be stopped during production. From this, the superiority of the continuous manufacturing method of the membrane electrode gas diffusion layer bonded body according to the present invention was shown.

10 ... Long electrolyte membrane,
20 ... Long catalyst layer,
40 ... A long gas diffusion layer,
41 ... A base material of a long gas diffusion layer,
42 ... Hopper,
43 ... Diffusion layer paste,
45 ... Drying furnace,
50 ... Long auxiliary material as a release sheet,
51 ... The base of auxiliary materials,
52 ... Wall,
53 ... dent,
55 ... Laminated body of gas diffusion layer and auxiliary materials,
55a ... Lower laminated body in entanglement roll,
55b ... Upper laminated body in entanglement roll,
56 ... Roll of laminated body,
57 ... reel,
60, 70 ... Electrodes that are a laminate of a long catalyst layer and a long gas diffusion layer,
61 ... Pressure welding roll,
80 ... Elongated membrane electrode gas diffusion layer junction,
100 ... Fuel cell.

Claims (1)

At least the step of laminating a long catalyst layer wound in a roll and a long gas diffusion layer wound in a roll on a long electrolyte membrane while unwinding from each roll. A method for continuously manufacturing a membrane electrode gas diffusion layer bonded body containing a film electrode.
The long gas diffusion layer is rolled up as a laminated body with a long auxiliary material, and the area ratio of the gas diffusion layer to the auxiliary material in the laminated body is 90% or less. In the roll, the back surface of the auxiliary material constituting the upper laminated body and the top surface of the auxiliary material constituting the lower laminated body are in contact with each other at a part thereof, and from the roll. At the time of unwinding, the auxiliary material and the gas diffusion layer are separated, and only the separated gas diffusion layer is sent out to the laminating step, and the width of the auxiliary material is the width of the gas diffusion layer. A method for continuously producing a membrane electrode gas diffusion layer bonded body, which is broader than the above and has a static friction coefficient of 1.2 or more of the auxiliary material.

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