Method for evaluating transfer film for forming catalyst layer

Abstract

The problem to be solved by the present invention is to provide a method for evaluating a transfer film for forming a catalyst layer, the method being capable of accurately evaluating the operability during transfer such as the occurrence of transfer defects in the catalyst layer for a transfer film for forming a catalyst layer that is likely to break. In order to solve the problem, the present invention provides a method for evaluating a catalyst layer-forming transfer film which is laminated on a base material and forms a catalyst layer of a fuel cell by transfer printing, the method for evaluating a catalyst layer-forming transfer film comprising measuring a horizontal force while moving a cutting blade by means of the SAICAS method, and measuring the horizontal force while moving the cutting blade by means of the SAICAS method. The maximum value of the horizontal force during the period from when the cutting blade is inserted into the transfer film for forming the catalyst layer to when the transfer film for forming the catalyst layer is broken is obtained, and the operability of the transfer film for forming the catalyst layer during transfer is evaluated on the basis of the maximum value of the horizontal force.

Description

Technical Field

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

[0002] In recent years, in order to ensure that more people can obtain affordable, reliable, sustainable, and advanced energy, research and development related to fuel cells that contribute to energy efficiency improvement have been carried out. A fuel cell generally has a membrane electrode assembly (MEA), and the membrane electrode assembly includes an anode-side catalyst layer and a cathode-side catalyst layer that are disposed opposite to each other with an electrolyte membrane interposed therebetween. As a method for manufacturing the membrane electrode assembly, a transfer film for forming a catalyst layer is transferred onto the electrolyte membrane. In order to avoid poor transfer of the catalyst layer, a method for evaluating the occurrence of poor transfer in the state of the transfer film for forming a catalyst layer has been studied. For example, the following evaluation method has been studied: using the SAICAS method, the vertical force and the horizontal force when a cutting tool reaches the interface between the transfer film and the substrate of the transfer film are measured, and based on the quotient obtained by dividing the value of the vertical force by the value of the horizontal force, it is predicted whether poor transfer occurs (for example, refer to Patent Document 1).

[0003] [Prior Art Documents]

[0004] (Patent Documents)

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2020-173905 Summary of the Invention

[0006] [Problems to be Solved by the Invention]

[0007] However, in the technology related to fuel cells, one of the problems is the improvement of productivity. Therefore, there is a need for an evaluation method that can accurately evaluate the occurrence of poor transfer of the catalyst layer even when using various transfer films for forming a catalyst layer. However, since the conventional evaluation method using the SAICAS method measures the vertical force and the horizontal force when a cutting tool reaches the interface between the transfer film for forming a catalyst layer and the substrate, it cannot be applied to the case where the transfer film for forming a catalyst layer breaks during the cutting tool reaching the interface.

[0008] The present invention has been completed in view of the above circumstances, and an object thereof is to provide an evaluation method for a transfer film for forming a catalyst layer, which can accurately evaluate the operability during transfer such as the occurrence of poor transfer of the catalyst layer for a transfer film for forming a catalyst layer that is likely to break. And further contribute to the improvement of energy efficiency.

[0009] [Means for Solving the Problems]

[0010] The present inventor has found that, from the horizontal force data measured while moving a cutting knife using the SAICAS method, the maximum value of the horizontal force during the period from when the measuring cutting knife is inserted into the transfer film for forming a catalyst layer until the transfer film for forming a catalyst layer breaks is used to evaluate the operability during transfer. Thus, the above problems can be solved, and the present invention is completed.

[0011] (1) A method for evaluating a transfer film for forming a catalyst layer, the transfer film for forming a catalyst layer being laminated on a substrate and forming a catalyst layer of a fuel cell by transfer. The method for evaluating the transfer film for forming a catalyst layer uses the SAICAS method to measure the horizontal force while moving a cutting knife, obtains the maximum value of the horizontal force during the period from when the cutting knife is inserted into the transfer film for forming a catalyst layer until the transfer film for forming a catalyst layer breaks, and evaluates the operability of the transfer film for forming a catalyst layer during transfer based on the maximum value of the horizontal force.

[0012] According to the method for evaluating a transfer film for forming a catalyst layer in (1), from the data of the horizontal force measured while moving a cutting knife, the maximum value of the horizontal force during the period from when the cutting knife is inserted into the transfer film for forming a catalyst layer until the transfer film for forming a catalyst layer breaks is used. Therefore, even in the case where the transfer film for forming a catalyst layer is easily broken, the operability during transfer can be accurately predicted.

[0013] (2) According to the method for evaluating a transfer film for forming a catalyst layer in (1), wherein the operability during transfer includes: whether there is peeling and cracking of the transfer film for forming a catalyst layer shortly after the transfer film for forming a catalyst layer is transferred to the electrolyte membrane of the fuel cell.

[0014] According to the method for evaluating a transfer film for forming a catalyst layer in (2), based on the above horizontal force, it is possible to predict whether there is peeling and cracking of the transfer film for forming a catalyst layer shortly after the transfer film for forming a catalyst layer is transferred to the electrolyte membrane of the fuel cell.

[0015] (3) According to the method for evaluating a transfer film for forming a catalyst layer in (2), wherein the operability during transfer further includes: whether there is peeling and cracking of the transfer film for forming a catalyst layer when a torsional external force is applied to the transfer film for forming a catalyst layer.

[0016] According to the method for evaluating a transfer film for forming a catalyst layer in (3), based on the above horizontal force, it is possible to predict whether there is peeling and cracking of the transfer film for forming a catalyst layer when a torsional external force is applied to the transfer film for forming a catalyst layer.

[0017] (Advantages of the Invention)

[0018] According to the present invention, an evaluation method for a transfer film for forming a catalyst layer can be provided, which can accurately evaluate the operability 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 DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 FIG. is a cross-sectional view showing an example of a transfer material of a transfer film for forming a catalyst layer that is an object to be evaluated in the evaluation method of the transfer film for forming a catalyst layer according to an embodiment of the present invention.

[0020] Figure 2 FIG. is a cross-sectional view showing a state after the transfer film for forming a catalyst layer is broken in the evaluation method of the transfer film for forming a catalyst layer according to an embodiment of the present invention.

[0021] Figure 3 FIG. is a graph showing data of the horizontal force of the transfer film for forming a catalyst layer measured in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] Hereinafter, an evaluation method for a transfer film for forming a catalyst layer according to an embodiment of the present invention will be described with reference to the drawings. However, the embodiments shown below are illustrative of the present invention, and the present invention is not limited to the following content.

[0023] Figure 1 FIG. is a cross-sectional view showing an example of a transfer material of a transfer film for forming a catalyst layer that is an object to be evaluated in the evaluation method of the transfer film for forming a catalyst layer according to an embodiment of the present invention.

[0024] As Figure 1 shown, the transfer material 10 is a laminate in which a transfer film 11 for forming a catalyst layer and a substrate 12 are laminated. The peel strength of the transfer film 11 for forming a catalyst layer can be in the range of 0.01 N / cm or more and 0.2 N / cm or less.

[0025] The substrate 12 is a member that supports the transfer film 11 for forming a catalyst layer. As the substrate 12, there is no particular limitation, and a substrate used in conventional transfer materials can be used. The transfer film 11 for forming a catalyst layer is transferred onto the surface of the electrolyte membrane of a fuel cell to form a catalyst layer of the fuel cell. The catalyst layer can be a cathode-side catalyst layer or an anode-side catalyst layer. The transfer film 11 for forming a catalyst layer is cut by a cutting knife before the cutting knife reaches the interface between the substrate 12 and the transfer film 11 for forming a catalyst layer in the SAICAS method. As the transfer film 11 for forming a catalyst layer, there is no particular limitation, and a transfer film used in conventional catalyst layers of fuel cells can be used.

[0026] In the evaluation method of the transfer film for forming a catalyst layer according to the present embodiment, the horizontal force is measured while moving the cutting knife by the SAICAS method. Then, from the measured horizontal force data, the maximum value of the horizontal force during the period from when the measurement cutting knife is inserted into the transfer film for forming a catalyst layer until the transfer film for forming a catalyst layer breaks is obtained.

[0027] Figure 2 is a cross-sectional view showing the state after the transfer film for forming a catalyst layer breaks.

[0028] As Figure 2 shown, in the Surface And Interfacial Cutting Analysis System (SAICAS) method, the cutting knife 20 with a relatively sharp tip 21 is inserted from the surface of the transfer film 11 for forming a catalyst layer and moved obliquely downward at a constant speed ( Figure 2 in the direction of the arrow). The horizontal force is the force applied to the cutting knife 20 in the horizontal direction of the transfer film 11 for forming a catalyst layer. In the present embodiment, before the transfer film 11 for forming a catalyst layer and the cutting knife 20 reach the interface with the substrate 12, a fracture part 15 is formed on the transfer film 11 for forming a catalyst layer. For example, after measuring the horizontal force, the generation of the fracture part 15 in the transfer film 11 for forming a catalyst layer can be confirmed by observing the cross-section of the transfer film 11 for forming a catalyst layer.

[0029] Figure 3 is a graph showing the data of the horizontal force of the transfer film for forming a catalyst layer measured in Example 1 below. In Figure 3 the graph, the horizontal axis is the time after the cutting knife 20 is inserted, and the vertical axis is the horizontal force. From Figure 3 the graph, it can be seen that the horizontal force increases as time passes, that is, as the insertion depth of the cutting knife 20 becomes deeper, and then decreases sharply. The time point when the horizontal force decreases sharply is the moment when the transfer film 11 for forming a catalyst layer breaks. The maximum value of the horizontal force is usually the horizontal force just before the transfer film 11 for forming a catalyst layer breaks.

[0030] In the evaluation method of the transfer film for forming a catalyst layer according to the present embodiment, the operability of the transfer film 11 for forming a catalyst layer during transfer is evaluated based on the maximum value of the horizontal force. The evaluation criteria vary depending on main factors such as the affinity between the transfer film 11 for forming a catalyst layer and the electrolyte membrane for transferring the transfer film 11 for forming a catalyst layer, and thus cannot be uniformly specified. Usually, a case where the maximum value of the horizontal force is 0.2 N or more is considered qualified.

[0031] According to the evaluation method of the transfer film for forming a catalyst layer of the present embodiment configured as above, from the data of the horizontal force measured while moving the cutting knife 20, the maximum value of the horizontal force during the period from when the cutting knife 20 is inserted into the transfer film 11 for forming a catalyst layer until the transfer film 11 for forming a catalyst layer breaks is used. Therefore, even if the transfer film 11 for forming a catalyst layer is easily broken, the operability such as the occurrence of poor transfer to the electrolyte membrane can be accurately predicted. For example, based on the above horizontal force, it is possible to predict whether there is peeling or cracking of the transfer film for forming a catalyst layer shortly after transferring the transfer film for forming a catalyst layer to the electrolyte membrane of a fuel cell. Furthermore, based on the above horizontal force, it is possible to predict whether there is peeling or cracking of the transfer film for forming a catalyst layer when a torsional external force is applied to the transfer film for forming a catalyst layer.

[0032] [Example]

[0033] [Example 1]

[0034] Prepare the transfer materials for Samples 1 to 4. The transfer material is a laminate in which a transfer film for forming a catalyst layer and a base material are laminated.

[0035] The horizontal force of the transfer film for forming a catalyst layer of each sample was measured by the SAICAS method. The results are shown in Figure 3 , and the maximum horizontal force is shown in Table 1 below. The measurement of the horizontal force was performed using SAICAS (DN-GS type, manufactured by DAIPLA WINTES CO., LTD.). The cutting knife used was a ceramic blade with a blade width of 1 mm, a rake angle of 20 degrees, a clearance angle of 10 degrees, and a material of cubic boron nitride. The measurement conditions were: measurement mode: constant speed mode, vertical speed: 0.5 μm / sec, horizontal speed: 5 μm / sec. In addition, the cross-section of the transfer film for forming a catalyst layer after measuring the horizontal force was observed using a scanning electron microscope (SEM). As a result, all the transfer films for forming a catalyst layer of Samples 1 to 4 were broken.

[0036] The peel strength of the transfer film for forming a catalyst layer of each sample was measured. The results are shown in Table 1 below. The peel strength was measured using a 90-degree peel strength test. The transfer material was cut in a length of 100 mm and a width of 20 mm to prepare a sample for peel strength measurement. The transfer film for forming a catalyst layer of the sample for peel strength measurement was on the lower side and the substrate was on the upper side, and a double-sided tape (5000NS-25, manufactured by NITTO DENKO CORPORATION) was used to stick it on the test device table. The substrate of the transfer film for forming a catalyst layer was peeled off at a speed of 300 mm / min, and the 90-degree peel strength was measured. The surface of the peeled substrate was observed, and no transfer film for forming a catalyst layer was attached to any substrate of samples 1 to 4. Thus, it was confirmed that the peeling mode of the transfer film for forming a catalyst layer in the 90-degree peel strength test was interface peeling.

[0037] The workability of each sample during transfer was evaluated by the following method. The results are shown in Table 1 below.

[0038] (Evaluation of operability during transfer)

[0039] The transfer film for forming a catalyst layer of the sample is overlapped with the surface of the electrolyte membrane, and the obtained stack is arranged on a pressurizing device through a buffer material, and is pressed flat under the conditions of temperature: 136°C, pressure: 30kgf / cm2, and pressing time: 5sec. After the transfer film for forming a catalyst layer is pressed onto the electrolyte membrane, the substrate of the sample is peeled off to obtain an electrolyte membrane-catalyst layer-forming transfer film stack after the transfer film for forming a catalyst layer is transferred onto the surface of the electrolyte membrane.

[0040] The surface of the transfer film for forming the catalyst layer was visually observed shortly after the transfer to confirm whether there was peeling and cracks of 1 mm or more. The results were as follows: 5 points were given for the number of peeling and cracks per 100 cm2 if 1 or less was given, 3 points were given for 2 or more and 5 or less, and 0 points were given for 6 or more. The scores are shown in Table 1.

[0041] The electrolyte membrane-catalyst layer forming transfer film laminate was transported to a roller with a radius of 80 mm under a wrap angle of 90 degrees, and a torsional external force was applied to the catalyst layer forming transfer film. After applying the torsional external force, it was confirmed whether there was peeling of the catalyst layer forming transfer film and cracks of 1 mm or more. As a result, the number of peeling and cracks per 100 cm2 was 1 or less and 5 points were set to 3 points, and 6 or more were set to 0 points. The scores are shown in Table 1.

[0042] Find the total score of the transfer film for forming the catalyst layer shortly after transfer and the catalyst layer laminate after applying torsional external force. Set the total score of 8 or more as A, 5 or more and 6 or less as B, and 3 or less as C. The results are shown in Table 1.

[0043] [Table 1]

[0044]

[0045] From the results in Table 1, it can be seen that there is a high correlation between the maximum value of the horizontal force measured by the SAICAS method and the operability during transfer.

[0046] Reference numeral

[0047] 10 Transfer material

[0048] 11 Transfer film for forming catalyst layer

[0049] 12 Substrate

[0050] 15 Fracture part

[0051] 20 Cutting knife

[0052] 21 Tip

Claims

1. A method for evaluating a transfer film for forming a catalyst layer, wherein the transfer film for forming a catalyst layer is laminated on a substrate, and a catalyst layer of a fuel cell is formed by transfer. The method for evaluating the transfer film for forming a catalyst layer uses the SAICAS method to measure the horizontal force while moving a cutting knife. The maximum value of the horizontal force during the period from when the cutting knife is inserted into the transfer film for forming a catalyst layer to when the transfer film for forming a catalyst layer breaks is obtained, and based on the maximum value of the horizontal force, the operability of the transfer film for forming a catalyst layer during transfer is evaluated.

2. The evaluation method of the transfer film for forming a catalyst layer according to claim 1, wherein, The operability during the transfer includes: whether there is peeling and cracking of the transfer film for forming a catalyst layer shortly after the transfer film for forming a catalyst layer is transferred to the electrolyte membrane of the fuel cell.

3. The evaluation method of the transfer film for forming a catalyst layer according to claim 2, wherein, The operability during the transfer further includes: whether there is peeling and cracking of the transfer film for forming a catalyst layer when a torsional external force is applied to the transfer film for forming a catalyst layer.

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