Evaluation method for transfer membrane for catalyst layer formation

Abstract

To provide an evaluation method of a transfer membrane for a catalyst layer formation, capable of accurately evaluating handling properties at the time of transfer, such as occurrence of defective transfer of a catalyst layer, with respect to the transfer membrane for the catalyst layer formation that is easily broken.SOLUTION: The present invention provides an evaluation method of a transfer membrane of a catalyst layer formation that is laminated on a substrate and forms a catalyst layer of a fuel battery by transfer, in which a horizontal force is measured while moving a cutting blade by a SAICAS method, a maximum value of the horizontal force between when the cutting blade is inserted into the transfer membrane of the catalyst layer formation and when the transfer membrane of the catalyst layer formation breaks, and a handling property of the transfer membrane of the catalyst layer formation at the time of transfer is evaluated based on the maximum value of the horizontal force.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for evaluating a transfer film for forming a catalyst layer. [Background technology]

[0002] In recent years, research and development into fuel cells, which contribute to energy efficiency, has been conducted to ensure that more people have access to affordable, reliable, sustainable, and advanced energy. Fuel cells generally have an electrode assembly (MEA) including an anode catalyst layer and a cathode catalyst layer that are arranged opposite each other with an electrolyte membrane interposed between them. One method for manufacturing an electrode assembly involves transferring a transfer membrane for forming a catalyst layer onto the electrolyte membrane. To avoid transfer defects of the catalyst layer, evaluation methods have been developed that can evaluate the occurrence of transfer defects while the transfer membrane for forming the catalyst layer is in its state. For example, an evaluation method has been developed that uses the SAICAS method to measure the vertical and horizontal forces when a cutting blade reaches the interface between the transfer membrane and the substrate of the transfer membrane, and predicts the occurrence of transfer defects based on the quotient obtained by dividing the vertical force value by the horizontal force value (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-173905 Summary of the Invention [Problem to be solved by the invention]

[0004] In fuel cell technology, improving productivity is one of the challenges. Therefore, an evaluation method that can accurately evaluate the occurrence of catalyst layer transfer failures even when various catalyst layer transfer films are used is desired. However, conventional evaluation methods using the SAICAS method measure the vertical and horizontal forces when the cutting blade reaches the interface between the catalyst layer transfer film and the substrate, so they are not applicable when the catalyst layer transfer film breaks before the cutting blade reaches the interface.

[0005] The present invention has been made in view of the above circumstances, and aims to provide a method for evaluating a transfer film for forming a catalyst layer, which can accurately evaluate the handling characteristics during transfer, such as the occurrence of transfer failure of a catalyst layer, for a transfer film for forming a catalyst layer that is prone to breakage, and which will ultimately contribute to improving energy efficiency. [Means for solving the problem]

[0006] The inventors discovered that the above problem could be solved by evaluating the handling properties during transfer using the maximum value of horizontal force from the time the measuring cutting blade is inserted into the transfer film for forming a catalyst layer until the transfer film for forming a catalyst layer breaks, from the horizontal force data measured while moving the cutting blade using the SAICAS method, and thus completed the present invention.

[0007] (1) A method for evaluating a transfer film for forming a catalyst layer, which is laminated on a substrate and forms a catalyst layer of a fuel cell by transfer, comprising: measuring horizontal force while moving a cutting blade using the SAICAS method; obtaining the maximum value of horizontal force from when the cutting blade is inserted into the transfer film for forming a catalyst layer until the transfer film for forming a catalyst layer breaks; and evaluating the handleability of the transfer film for forming a catalyst layer during transfer based on the maximum value of horizontal force.

[0008] According to the evaluation method of the transfer membrane for forming a catalyst layer (1), the maximum value of the horizontal force from the time the cutting blade is inserted into the transfer membrane for forming a catalyst layer until the transfer membrane for forming a catalyst layer breaks is used from the horizontal force data measured while the cutting blade is moved. Therefore, even if the transfer membrane for forming a catalyst layer is prone to breakage, the handling properties during transfer can be accurately predicted.

[0009] (2) The method for evaluating a transfer film for forming a catalyst layer according to (1), wherein the handling property during transfer includes the presence or absence of peeling and cuts in the transfer film for forming a catalyst layer immediately after transferring the transfer film for forming a catalyst layer to the electrolyte membrane of the fuel cell.

[0010] According to the evaluation method of the transfer membrane for forming a catalyst layer (2), the presence or absence of peeling and cuts in the transfer membrane for forming a catalyst layer immediately after the transfer membrane for forming a catalyst layer is transferred to the electrolyte membrane of the fuel cell can be predicted from the above horizontal force.

[0011] (3) The method for evaluating a transfer film for forming a catalyst layer according to (2), wherein the handleability during transfer further includes the presence or absence of peeling and cuts in the transfer film for forming a catalyst layer when a twisting external force is applied to the transfer film for forming a catalyst layer.

[0012] According to the evaluation method of the transfer membrane for forming a catalyst layer (3), it is possible to predict from the above horizontal force whether or not the transfer membrane for forming a catalyst layer will peel off or have a cut when a torsional external force is applied to the transfer membrane for forming a catalyst layer. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a method for evaluating a transfer film for forming a catalyst layer, which can accurately evaluate the handling characteristics during transfer, such as the occurrence of transfer defects of the catalyst layer, for a transfer film for forming a catalyst layer that is prone to breakage. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view of an example of a transfer material having a transfer film for forming a catalyst layer to be evaluated in a method for evaluating a transfer film for forming a catalyst layer according to one embodiment of the present invention. [Figure 2] 1 is a cross-sectional view showing a state in which a transfer membrane for forming a catalyst layer is broken in a method for evaluating a transfer membrane for forming a catalyst layer according to one embodiment of the present invention. FIG. [Figure 3] 1 is a graph showing data on the horizontal force of the transfer membrane for forming a catalyst layer measured in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, a method for evaluating a transfer membrane for forming a catalyst layer according to one embodiment of the present invention will be described with reference to the accompanying drawings. However, the following embodiment is merely an example of the present invention, and the present invention is not limited to the following.

[0016] FIG. 1 is a cross-sectional view of an example of a transfer material having a transfer film for forming a catalyst layer, which is an evaluation target, in a method for evaluating a transfer film for forming a catalyst layer according to one embodiment of the present invention.

[0017] 1, the transfer material 10 is a laminate formed by laminating a catalyst layer-forming transfer film 11 and a substrate 12. The peel strength of the catalyst layer-forming transfer film 11 may be in the range of 0.01 N / cm or more and 0.2 N / cm or less.

[0018] The substrate 12 is a member that supports the transfer membrane 11 for forming a catalyst layer. There are no particular limitations on the substrate 12, and substrates used in conventional transfer materials can be used. The transfer membrane 11 for forming a catalyst layer is transferred to the surface of the electrolyte membrane of a fuel cell to form the catalyst layer of the fuel cell. The catalyst layer may be a cathode-side catalyst layer or an anode-side catalyst layer. The transfer membrane 11 for forming a catalyst layer is broken by a cutting blade used in the SAICAS method before the cutting blade reaches the interface between the substrate 12 and the transfer membrane 11 for forming a catalyst layer. There are no particular limitations on the transfer membrane 11 for forming a catalyst layer, and those used in catalyst layers of conventional fuel cells can be used.

[0019] In the method for evaluating the transfer membrane for forming a catalyst layer according to this embodiment, horizontal force is measured by the SAICAS method while moving the cutting blade, and the maximum value of the horizontal force from the time when the measuring cutting blade is inserted into the transfer membrane for forming a catalyst layer until the transfer membrane for forming a catalyst layer is broken is obtained from the measured horizontal force data.

[0020] FIG. 2 is a cross-sectional view showing a state in which the transfer film for forming a catalyst layer is broken. As shown in FIG. 2, in the SAICAS (Surface and Interfacial Cutting Analysis System) method, a cutting blade 20 with a sharp tip 21 is inserted into the surface of a catalyst layer formation transfer film 11 and moved diagonally downward (in the direction of the arrow in FIG. 2) at a constant speed. The horizontal force is a force applied to the cutting blade 20 in the horizontal direction of the catalyst layer formation transfer film 11. In this embodiment, a fracture 15 is formed in the catalyst layer formation transfer film 11 before the catalyst layer formation transfer film 11 and the cutting blade 20 reach the interface with the substrate 12. The formation of the fracture 15 in the catalyst layer formation transfer film 11 can be confirmed, for example, by observing the cross section of the catalyst layer formation transfer film 11 after measuring the horizontal force.

[0021] FIG. 3 is a graph showing data on the horizontal force of the transfer membrane for forming a catalyst layer measured in Example 1 described below. In the graph of FIG. 3, the horizontal axis represents the time since the cutting blade 20 was inserted, and the vertical axis represents the horizontal force. From the graph of FIG. 3, it can be seen that the horizontal force increases with the passage of time, i.e., as the insertion depth of the cutting blade 20 increases, and then drops sharply. The point at which the horizontal force drops sharply is when the transfer membrane for forming a catalyst layer 11 breaks. The maximum value of the horizontal force is usually the horizontal force just before the transfer membrane for forming a catalyst layer 11 breaks.

[0022] In the method for evaluating a catalyst layer-forming transfer membrane of this embodiment, the handleability during transfer of the catalyst layer-forming transfer membrane 11 is evaluated based on the maximum value of horizontal force. Evaluation criteria cannot be uniformly determined because they vary depending on factors such as the affinity between the catalyst layer-forming transfer membrane 11 and the electrolyte membrane to which it is transferred, but a maximum horizontal force of 0.2 N or more can usually be considered acceptable.

[0023] According to the catalyst layer formation transfer membrane evaluation method of this embodiment configured as described above, the maximum horizontal force measured while moving the cutting blade 20 is used from the horizontal force data from when the cutting blade 20 is inserted into the catalyst layer formation transfer membrane 11 until the catalyst layer formation transfer membrane 11 breaks. Therefore, even if the catalyst layer formation transfer membrane 11 is prone to breakage, it is possible to accurately predict handleability, such as the occurrence of transfer failure to the electrolyte membrane. For example, the horizontal force can be used to predict whether the catalyst layer formation transfer membrane will peel or break immediately after being transferred to the electrolyte membrane of a fuel cell. Furthermore, the horizontal force can be used to predict whether the catalyst layer formation transfer membrane will peel or break when a torsional external force is applied to the catalyst layer formation transfer membrane. [Example]

[0024] [Example 1] Transfer materials were prepared for Samples 1 to 4. The transfer materials were laminates in which a transfer film for forming a catalyst layer and a substrate were laminated together.

[0025] The horizontal force of the catalyst layer transfer membrane for each sample was measured using the SAICAS method. The results are shown in Figure 3, and the maximum horizontal force is shown in Table 1 below. The horizontal force was measured using a SAICAS (DN-GS type, manufactured by Daipla Wintes Co., Ltd.). The cutting blade used was a ceramic blade with a cutting width of 1 mm, a rake angle of 20 degrees, a clearance angle of 10 degrees, and a Borazon material. The measurement conditions were: measurement mode: constant speed mode, vertical speed: 0.5 μm / sec, horizontal speed: 5 μm / sec. After measuring the horizontal force, the cross sections of the catalyst layer transfer membranes were observed using a scanning electron microscope (SEM). It was found that all of the catalyst layer transfer membranes for samples 1 to 4 were fractured.

[0026] The peel strength of the transfer film for catalyst layer formation of each sample was measured. The results are shown in Table 1 below. Peel strength was measured using a 90-degree peel strength test. The transfer material was cut to a length of 100 mm and a width of 20 mm to prepare a sample for peel strength measurement. The sample for peel strength measurement was attached to the table of a testing device using double-sided tape (5000NS-25, manufactured by Nitto Denko Corporation) so that the transfer film for catalyst layer formation was on the bottom and the substrate was on the top. The substrate from which the transfer film for catalyst layer formation was attached was peeled off at a speed of 300 mm / min to measure the 90-degree peel strength. When the surface of the peeled substrate was observed, the transfer film for catalyst layer formation was not attached to the substrate for any of Samples 1 to 4. Therefore, the peel mode of the transfer film for catalyst layer formation in the 90-degree peel strength test was confirmed to be interfacial peeling.

[0027] The handling properties of each sample during transfer were evaluated by the following method, and the results are shown in Table 1 below.

[0028] (Evaluation of handling during transfer) The sample transfer membrane for forming a catalyst layer was superimposed on the surface of the electrolyte membrane, and the resulting laminate was placed in a press machine via a cushioning material, and the temperature was 136°C and the pressure was 30 kgf / cm. 2 The transfer membrane for forming a catalyst layer was pressed onto the electrolyte membrane by flat pressing under the conditions of 1000 kJ / cm2, 1000 kJ / cm2, and 1000 kJ / cm2 for a pressing time of 5 seconds. After that, the substrate of the sample was peeled off to obtain an electrolyte membrane-transfer membrane for forming a catalyst layer laminate in which the transfer membrane for forming a catalyst layer was transferred onto the surface of the electrolyte membrane.

[0029] The surface of the transfer film for forming the catalyst layer was visually observed immediately after transfer to check for peeling and cuts of 1 mm or more. 2 A score of 5 was given for one or less peeling or cut, a score of 3 for two to five peeling or cuts, and a score of 0 for six or more peeling or cuts. The scores are shown in Table 1.

[0030] The electrolyte membrane-transfer membrane for forming a catalyst layer laminate was transported around a roll with a radius of 80 mm at a wrap angle of 90 degrees, and a twisting force was applied to the transfer membrane for forming a catalyst layer. The transfer membrane for forming a catalyst layer to which a twisting force was applied was checked for peeling and the presence or absence of cuts of 1 mm or more. 2 A score of 5 was given for one or less peeling or cut, a score of 3 for two to five peeling or cuts, and a score of 0 for six or more peeling or cuts. The scores are shown in Table 1.

[0031] The score of the catalyst layer-forming transfer membrane immediately after transfer and the score of the catalyst layer laminate to which an external torsional force had been applied were summed up. A total score of 8 points or more was assigned an A, 5 to 6 points was assigned a B, and 3 points or less was assigned a C. The results are shown in Table 1.

[0032] [Table 1]

[0033] The results in Table 1 show that there is a high correlation between the maximum value of horizontal force measured by the SAICAS method and handling properties during transfer. [Explanation of symbols]

[0034] 10 Transfer material 11 Transfer film for forming catalyst layer 12 Base material 15 Breaking part 20 cutting blade 21 Tip

Claims

1. A method for evaluating a transfer film for forming a catalyst layer, which is laminated on a substrate and forms a catalyst layer of a fuel cell by transfer, comprising: Using the SAICAS method, horizontal force is measured while moving the cutting blade. A method for evaluating a transfer film for forming a catalyst layer, comprising obtaining a maximum value of horizontal force from when the cutting blade is inserted into the transfer film for forming a catalyst layer until the transfer film for forming a catalyst layer breaks, and evaluating the handleability of the transfer film for forming a catalyst layer during transfer based on the maximum value of horizontal force.

2. 2. The method for evaluating a transfer film for forming a catalyst layer according to claim 1, wherein the handling properties during transfer include the presence or absence of peeling and cuts in the transfer film for forming a catalyst layer immediately after the transfer film for forming a catalyst layer is transferred to the electrolyte membrane of the fuel cell.

3. The method for evaluating a transfer film for forming a catalyst layer according to claim 2, further comprising the step of determining whether or not the transfer film for forming a catalyst layer peels off or has a cut when a torsional external force is applied to the transfer film for forming a catalyst layer.

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