JP2004325346A - Method of detecting pinhole and method of producing membrane electrode assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of detecting a pinhole, which accurately detects pinhole defects in a transparent / translucent film formed on an opaque membrane. <P>SOLUTION: The method of detecting pinhole has a polymer membrane 2 irradiated with irradiation light 8, receives only a light of specific wavelength among the light emitted from the polymer molecule membrane, and detects the presence or the absence of the pinhole 1 in the polymer molecule membrane 2, based on the amount of light of the received light. By using this pinhole detection method, the film being an object to be inspected is irradiated with a light as the irradiation light which reacts with the components of the film, and only the light having a specific wavelength band is detected among light emitted from the film, after reacting with the irradiation light, and the pinhole 1 can be detected based on the amount of light of the detected light. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pinhole detection method for inspecting whether a pinhole is generated in a film or a film such as a polymer film of a fuel cell, and a method for producing a membrane electrode assembly (hereinafter, MEA).
[0002]
[Prior art]
BACKGROUND ART Polymer electrolyte fuel cells are characterized by low operating temperatures and high power densities, and therefore are being developed as power sources for next-generation vehicles and as batteries for home cogeneration systems. A fuel cell has a structure in which a stacked body (hereinafter referred to as a stack) is housed in a container. The stack is a basic structural unit (hereinafter, module) comprising an MEA having a structure in which an electrolyte membrane is sandwiched between a fuel electrode and an air electrode, and a separator serving as a conductive gas separation / supply plate sandwiched between adjacent MEAs. Are stacked in a number of tens (the number is determined according to a required output voltage). The MEA has a structure in which an anode catalyst layer serving as a fuel electrode, a polymer film serving as an electrolyte membrane, and a cathode catalyst layer serving as an air electrode are sandwiched between conductive gas diffusion layers (hereinafter referred to as GDLs (gas diffusion layers)). Is the heart of the fuel cell. For example, the thickness of each layer is 15 μm for the anode catalyst layer, 30 μm for the polymer film, and 15 μm for the cathode catalyst layer.
[0003]
The most common cause of MEA failure in the manufacturing stage is the generation of minute pinholes of several μm in the polymer film. When a normal MEA without pinholes is used as a fuel cell, hydrogen (fuel gas) is separated from electrons and ionized at the fuel electrode, hydrogen ions move through the electrolyte, and recombine with the electrons at the air electrode. To return to hydrogen, and then combine with oxygen in the air to form water. In this case, the Gibbs free energy of the reaction in which water is generated from hydrogen and oxygen is directly converted to electric energy (the driving force for moving hydrogen ions in the electrolyte) with extremely high efficiency. If there is a pinhole, hydrogen in the fuel electrode moves to the air electrode as a gas without being ionized, and is combined with oxygen by a catalyst at the air electrode to become water. In this case, the Gibbs free energy is released on the spot as thermal energy rather than electrical energy. The MEA is locally heated in the pinhole and degrades. As this proceeds, the battery becomes poor in characteristics.
[0004]
In the manufacture of polymer electrolyte fuel cells, a process is provided to check whether pinholes are generated in the polymer film that is the electrolytic film and to eliminate the polymer film with pinholes as defective. Can be In the conventional pinhole detection method, the characteristics of a completed stack are inspected, and whether or not a defective module is included in the stack is inspected. If the inspection found that the stack contained a module with a defective characteristic, the defective module in the stack was replaced. However, the work of disassembling the completed stack, replacing defective modules, and assembling the stack again requires a great deal of labor. Before being assembled into the stack, preferably before being assembled into the MEA, the polymer film is inspected for pinholes, and the polymer film having pinholes is removed from the production process. If it can be eliminated, the yield of the assembled stack or MEA can be significantly improved, and the effective man-hours can be significantly reduced.
[0005]
As a method for manufacturing the MEA, there is a coating method or the like.
The coating method is a method of manufacturing an MEA in which an anode catalyst layer, a polymer film, and a cathode catalyst layer are sequentially coated on a base material such as PET (Polyethylene Terephthalate). The cause of pinholes is that pinholes are generated due to bubbles or the like entering into the polymer material at the time of coating the polymer film, and there is a fine gap in the anode catalyst layer. The second is that the material is sucked and pinholes are generated. In both cases, it is necessary to inspect for the presence of pinholes after the application of the polymer film. In that case, it is necessary to inspect whether or not the transparent or translucent polymer film has a pinhole in a state where the non-transparent catalyst layer exists under the polymer film.
[0006]
Conventionally, a number of pinhole detection methods have been proposed, for example, a set of a halogen light source and an optical sensor disposed across a transparent or translucent film in the form of a tape to be inspected, in the film running direction. Along two places. A halogen light source illuminates the transparent or translucent film with light. An optical sensor receives the transmitted light of the film. When there is a pinhole, the amount of light received by the optical sensor is significantly increased as compared with a case where there is no pinhole. Utilizing this, there is a method of detecting a pinhole on a film (see Patent Document 1). This method cannot be applied to the detection of pinholes in a film or film obtained by closely attaching a non-transparent film or film to a transparent or translucent film or film to be inspected.
[0007]
As another method, a polarizing film, which is a test object in which a red release film and a transparent film are laminated, is placed on a support. The polarizing film is irradiated with green illumination light having a complementary color relationship with the red color of the release film, and the inspector observes the reflected light. Green light incident on the release film is absorbed by the red release film and is invisible. Only the green light reflected from the surface of the transparent film reaches the inspector's eyes. There is a method in which an inspector can detect only irregularities on a surface including a pinhole on the front side of a transparent film of a polarizing film (a side in contact with a release film is a back side), dust attached to the surface, and the like (Patent Document 2). reference). This method is a method for detecting unevenness, dirt, and the like on the surface of the polarizing film, and cannot detect only a pinhole penetrating the transparent film. Also, it cannot be used when the transparency of the transparent film is high. This method does not cause any problem, for example, unevenness on the surface, and cannot be used for detecting pinholes in a polymer film or film of a MEA of a fuel cell in which only a pinhole penetrating a transparent film causes a defect.
[0008]
As still another method, a light source, a polarizing plate, a transparent sheet to be inspected, another polarizing plate, and a light receiving section are arranged in this order. There is a method in which a transparent film is irradiated with light from a light source, and a light receiving unit detects light transmitted through a polarizing plate, a transparent sheet, and another polarizing plate (see Patent Document 3). This method is also not applicable to the detection of pinholes in a film or film in which a non-transparent film or film is closely adhered to a transparent or translucent film or film to be inspected.
[0009]
[Patent Document 1]
JP-A-2000-146861
[Patent Document 2]
JP 2001-108630 A
[Patent Document 3]
JP 06-18445 A
[0010]
[Problems to be solved by the invention]
As described above, in order to detect a pinhole present in a film or a film of a transparent or translucent inspection object existing on a non-transparent film or a film, the detection method has the following four conditions. It is necessary. (1) It has a detection sensitivity for detecting pinholes of several μm in size, (2) it is a non-destructive inspection and a non-contact inspection, and (3) it can be inspected in a non-vacuum state. (4) It is possible to detect a transparent or translucent film or a pinhole of a film present on an intransparent surface (for example, a film). Conventionally, there has been no pinhole detection method satisfying these four conditions.
[0011]
The present invention satisfies these conditions, and detects pinholes of several μm in a film or film of a transparent or translucent test object existing on a non-transparent film or film. It is an object to provide a method and a method for producing a membrane electrode assembly.
[0012]
[Means for Solving the Problems]
In order to solve the above problems, the present invention irradiates the inspection object with irradiation light, receives only light of a specific wavelength among the light generated from the inspection object, based on the amount of the received light, A pinhole detection method characterized by detecting the presence or absence of a pinhole in the inspection object.
[0013]
The present invention detects the reaction light according to the amount of the constituent substance of the test object, so that, for example, in the case of a reflection type configuration, regardless of the state of the surface opposite to the input surface of the irradiation light, Presence can be inspected with high accuracy, non-destructive and non-contact, and it is possible to accurately detect pinholes of several μm in non-transparent films and transparent or translucent inspection objects existing on films. .
Further, the irradiation light is ultraviolet light, and the inspection object receives only light having a wavelength near a wavelength at which the amount of fluorescent light generated in response to the ultraviolet light reaches a peak.
[0014]
Certain kinds of organic substances (for example, a polymer film such as a perfluorosulfonic acid film) generate strong reaction light which is fluorescence when excited by ultraviolet light. On the other hand, a catalyst layer formed below a polymer film in a fuel cell MEA or the like is unlikely to emit fluorescence even when irradiated with light having a short wavelength. INDUSTRIAL APPLICABILITY The present invention can detect, with high sensitivity, pinholes generated in a polymer film formed on a catalyst layer, for example, in a process of manufacturing an MEA for a fuel cell.
Further, the irradiation light is visible light, and the inspection object receives only light having a wavelength near a wavelength at which a light amount of light generated by causing Raman scattering by the visible light reaches a peak.
[0015]
When a substance (for example, a polymer film such as a perfluorosulfonic acid film) is excited by visible light or near-infrared light, Raman scattering occurs according to the shape of the molecule of the substance. The generated Raman scattered light has a wavelength shifted from the wavelength of the irradiation light, and has a narrow peak having a different wavelength depending on the shape of the molecule of the substance. The wavelength of the Raman scattered light varies depending on the shape of the molecule of the substance. Therefore, for example, the wavelength of Raman scattered light is different between a polymer film such as an MEA of a fuel cell and a catalyst layer formed thereunder. Since the half width of the spectrum of the Raman scattered light is narrow, it is easy to discriminate the Raman scattered light of the polymer film from the Raman scattered light of the catalyst layer.
ADVANTAGE OF THE INVENTION This invention can detect the pinhole which generate | occur | produced in the transparent or translucent film formed on the non-transparent film with high sensitivity based on the light quantity near the peak wavelength of Raman scattering light.
According to the present invention, even when a catalyst layer formed below a polymer film such as a MEA of a fuel cell emits fluorescence when irradiated with ultraviolet light, a pinhole of the polymer film to be inspected is formed. Can be detected.
[0016]
Further, the irradiation light is X-rays, and only X-rays having a wavelength near a wavelength at which the intensity of fluorescent X-rays generated by the reaction of the inspection target with the X-rays reaches a peak are received.
When a certain kind of organic substance (for example, a polymer film such as a perfluorosulfonic acid film) is excited by X-rays, it generates strong reaction light that is fluorescent X-rays. On the other hand, the catalyst layer formed below the polymer film in the MEA or the like of the fuel cell does not emit fluorescent X-rays even when irradiated with X-rays. INDUSTRIAL APPLICABILITY The present invention can detect, with high sensitivity, pinholes generated in a polymer film formed on a catalyst layer, for example, in a process of manufacturing an MEA for a fuel cell.
[0017]
Further, a predetermined material is applied on the base to form an anode catalyst layer, and another predetermined material is applied thereon to form a polymer film, and the presence or absence of pinholes in the polymer film is inspected. A method for producing a membrane electrode assembly, characterized in that a cathode catalyst layer is formed by applying another predetermined material thereon only when judged as non-defective by the inspection.
[0018]
According to the present invention, since the yield of the completed MEA is extremely good, the rate of repairing the stack due to poor characteristics after the completion of the stack is greatly reduced. The present invention realizes an MEA production method that has a good yield and can reduce the number of repair steps in a later process by a coating method. According to the production method of the present invention, an inexpensive fuel cell can be realized.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments that specifically illustrate the best mode for carrying out the present invention will be described below with reference to the drawings.
[0020]
<< Embodiment 1 >>
Hereinafter, a pinhole detection device, a pinhole detection method, and a MEA production method according to Embodiment 1 of the present invention will be described with reference to FIGS.
FIG. 1 is a diagram showing a configuration of a pinhole detection device according to Embodiment 1 of the present invention. In FIG. 1, 2 is a polymer film, 1 is a pinhole formed in the polymer film 2, 3 is a catalyst layer, 4 is a base film, 5 is an illumination light source, 6 is an illumination wavelength filter, 7 is a projection lens, 8 Is illumination light output from the illumination light source 5, 9 is light having a shifted wavelength, 10 is a light receiving lens, 11 is a light receiving wavelength filter, 12 is an optical sensor, 13 is a pinhole detector, 14 is a monitor television, and 15 is a controller. , 16 are an X-axis drive unit, 17 is a Y-axis drive unit, 18 is a work chuck, 19 is an X-axis, and 20 is a Y-axis.
[0021]
The inspection object (the polymer membrane 2, the catalyst layer 3, and the base film 4) is in the middle of the process of manufacturing the MEA of the fuel cell. A method for producing an MEA according to the present embodiment will be described. First, a predetermined material is applied on the base to form the anode catalyst layer 3 having a thickness of 15 μm. The catalyst layer 3 is a black, non-transparent substance obtained by mixing a catalyst such as platinum with a conductor such as carbon. Next, another predetermined material is applied on the catalyst layer 3 to form the transparent or translucent polymer film 2 having a thickness of 30 μm. The polymer film 2 is a transparent substance such as a perfluorosulfonic acid film. In the state thus formed, whether or not the polymer film 2 has a pinhole is inspected by a pinhole detection method described below. The polymer film 2, the catalyst layer 3, and the base film 4 shown in FIG. 1 are those at the time when the formation of the polymer film is completed. Only when it is determined in the inspection that there is no pinhole having a predetermined threshold value or more in the polymer film 2, another predetermined material is applied thereon to form a cathode catalyst layer. In this way, MEA is produced at a high yield by the coating method.
Here, the “predetermined threshold” is an arbitrary value. For example, the threshold is a threshold for the size of one pinhole. The threshold may be a fixed threshold or a floating threshold. For example, a pass / fail judgment may be made by applying a predetermined threshold value to the result of differentiating the image.
[0022]
Returning to the description of FIG. The work chuck 18, the X axis 19, and the Y axis 20 are included in the inspection stage. The control unit 15 controls the X-axis drive unit 16 and the Y-axis drive unit 17 to drive the work chuck 18 of the inspection stage in the X-axis direction and the Y-axis direction. The work chuck 18 of the inspection stage mounts the base film 4 on which the catalyst layer 3 and the polymer film 2 to be inspected are formed.
[0023]
The pinhole detection device and the pinhole detection method according to the present embodiment have an object to detect a pinhole 1 of about 1 μm existing in a polymer film 2 to be inspected.
Of the light emitted from the illumination light source 5 which is a mercury lamp, the illumination wavelength filter 6 passes only ultraviolet light having a wavelength of 300 nm or less. The light that has passed through the illumination wavelength filter 6 is condensed by a light projecting lens 7 and illuminated as illumination light 8 onto an inspection object. The illumination light 8 is an area illumination for irradiating a wider range than the inspection visual field described later.
The illumination light 8 applied to the inspection object excites the inspection object, and changes into fluorescence 9 whose wavelength is shifted to a longer wavelength side. The fluorescent light 9 is collected by the light receiving lens 10. The light-receiving wavelength filter 11 transmits only light having a wavelength of 320 nm to 430 nm among the fluorescent light 9 collected by the light-receiving lens 10. The optical sensor 12 receives light that has passed through the light receiving lens 10.
The optical sensor 12 converts the fluorescence that has passed through the light-receiving wavelength filter 11 into an electrical detection signal and outputs the signal to the pinhole detector 13. The optical sensor 12 according to the embodiment is an area CCD.
[0024]
In the first embodiment, the size of the inspection object is 100 mm × 100 mm. The pinhole detection device needs to inspect the entire surface of the inspection object.
In order to detect the pinhole 1 of 1 μm, the pixel resolution is set to 1 μm. The optical sensor 12 has a size of 2000 pixels × 2000 pixels, and the inspection visual field size is set to 2 mm × 2 mm.
As shown in FIG. 3, the control unit 15 moves the inspection object at a pitch of the inspection visual field size. The optical sensor 12 inputs an image, and the pinhole detection unit 13 performs image processing on 2500 visual fields.
[0025]
The electronic shutter function of the optical sensor 12 is used to speed up the pinhole inspection. Instead of the optical sensor 12 inputting an image after the control unit 15 stops the X-axis driving unit 16 for each field of view, the X-axis driving unit 16 moves the inspection target at a constant speed in the X-axis direction. The optical sensor 12 continuously inputs an image in a state where the electronic shutter function is operated, and the pinhole detection unit 13 processes the input image. When moving the inspection object by one field of view in the Y-axis direction, the optical sensor 12 inputs an image after the control unit 15 stops the Y-axis driving unit 17. That is, the inspection object is scanned relatively to the inspection visual field in the X-axis direction and the Y-axis direction. In the embodiment, when the pinhole detection unit 13 completes the image processing within 0.05 seconds, the pinhole detection device can perform an inspection in 0.05 seconds per 2 mm × 2 mm visual field. As shown in FIG. 3, while the X-axis driving unit 16 moves the inspection target at a speed of 40 mm / sec in the X-axis direction in the main scanning direction, the optical sensor 12 operates every 0.05 seconds for 0.0001 seconds. Input an image with the electronic shutter. The pinhole detection device can complete the inspection of the entire surface of the inspection object in 125 seconds.
[0026]
The pinhole detector 13 includes an A / D converter 131, an image processor 132, an image determiner 133, and an image generator 134. The pinhole detector 13 detects whether or not there is a pinhole in the polymer film by a method described below, and outputs a detection result. In the first embodiment, pinhole detector 13 is a personal computer.
The A / D converter 131 converts an output signal of the optical sensor 12 into a digital signal. The image processing unit 132 and the image determination unit 133 are functions executed by the CPU by software. The image processing unit 132 creates a bright and dark image corresponding to the intensity (light amount) of the fluorescence received by the optical sensor 12 for each visual field, and outputs the bright and dark image to the image determining unit 133.
The image determining unit 133 determines the location and size of the pinhole 1 based on the bright and dark images for each visual field corresponding to the intensity of the fluorescence created by the image processing unit 132.
[0027]
The image generation unit 134 generates an image indicating the location and size of the pinhole 1 for each inspection visual field. The monitor television 14 displays this image. FIG. 2 shows an example of an image generated by the image generation unit 134.
The portion where the pinhole 1 exists is dark because no fluorescence is generated. The image determining unit 133 detects the darkened portion by image processing. For example, the location and size of the pinhole 1 can be calculated by extracting a region where the amount of light received by the optical sensor 12 is less than a predetermined threshold and calculating the area and the center of gravity by labeling. The operator can check each image on the monitor TV 14 or display another screen on the monitor TV 14 during maintenance for convenience. The image determination unit 133 may automatically determine the quality of the inspection target based on the size of the pinhole 1.
[0028]
The light receiving wavelength filter 11 will be described. The light receiving wavelength filter 11 is a filter that passes only light having a wavelength of 320 nm to 430 nm. The reason will be described with reference to FIG.
The graph in FIG. 4 is data obtained by irradiating the polymer film 2 and the catalyst layer 3 with ultraviolet light having a wavelength of 280 nm as excitation light and measuring the respective spectral characteristics using a spectrophotometer. The polymer film 2 or the catalyst layer 3 emits light shifted to a longer wavelength side than the excitation light in response to the excitation light. FIG. 4 shows the spectral intensity of light emitted from the polymer film 2 and the catalyst layer 3. The polymer film 2 has a light intensity peak at 367.6 nm. On the other hand, the catalyst layer 3 has a small amount of light in the entire wavelength range. Therefore, when the wavelength is around 367.6 nm, the difference in the amount of light between the portion where the polymer film 2 exists and the portion where the pinhole 1 is formed is clear.
[0029]
As shown in FIG. 4, if only the light having a wavelength of 367.6 nm, which is the peak of fluorescence, is extracted by the light receiving wavelength filter 11, the portion where the polymer film 2 exists at a high S / N ratio and the pinhole 1 It is possible to discriminate a certain portion where the polymer film 2 does not exist. Based on this, the light-receiving wavelength filter 11 is a filter that passes only light having a wavelength of 320 nm to 430 nm as shown by hatching in FIG. Since the pass band of the light-receiving wavelength filter 11 does not include the wavelength of the excitation light (280 nm), a portion where the polymer film 2 exists at a higher S / N ratio and a portion where the polymer film 2 which is the pinhole 1 does not exist. And can be distinguished.
If the light-receiving wavelength filter 11 is not used, the S / N ratio decreases, and the detection performance decreases. When the pinhole is inspected by simply irradiating the inspection object with the white light without using the fluorescent light and inspecting the pinhole based on the intensity of the reflected light, the brightness depends on the unevenness of the surface of the polymer film 2 and the presence or absence of the pinhole 1. Light / dark cannot be separated, and pinhole 1 cannot be detected.
[0030]
Next, the reason why ultraviolet light (wavelength = 280 nm) is selected as the excitation light and the illumination wavelength filter 6 will be described. The fluorescence intensity from the polymer film 2 was measured by the above-described spectrophotometer while changing the wavelength of the excitation light. As a result, it was found that the shorter the wavelength, the higher the fluorescence intensity. A mercury lamp is a short-wavelength light source that can be obtained at relatively low cost, and the shortest wavelength peak of the mercury lamp is 280.4 nm. Therefore, the illumination wavelength filter 6 is a filter that passes only light having a wavelength of 300 nm or less, and illuminates the inspection object with ultraviolet light having a peak at 280.4 nm.
[0031]
In the present embodiment, the inspection object is a state in which the polymer film 2 is formed on the catalyst layer 3, but the inspection can be performed with a single polymer film.
On the detection principle, there is a correlation between the amount of the polymer film 2 and the amount of fluorescent light. Using the density data of the bright and dark images output by the image determination unit 133, not only the pinhole 1 but also the bubbles inside the polymer film 2 in which the amount of the polymer film 2 fluctuates, and the thickness of the polymer film 2 Unevenness and the like can also be detected.
In the present embodiment, the incident light source is an area illumination, and the optical sensor 12 is an area CCD. However, the object to be inspected is determined by using a combination of a line illumination and a line CCD or a combination of a point illumination and a point light receiving element such as a photomultiplier. May be scanned.
The method of detecting the pinhole 1 by image processing may be a floating threshold instead of a fixed threshold. Further, a differentiation process may be used.
[0032]
The MEA is manufactured by using the polymer membrane 2 in which the pinhole inspection of the polymer membrane for the fuel cell is performed by the method described in this embodiment and the pinhole 1 having a diameter of 1 μm or more is not present. I do. Thereby, the non-defective rate of the MEA can be greatly improved. As compared with a case where a defect of a polymer film is found in a later step, a man-hour loss in production can be greatly reduced.
[0033]
<< Embodiment 2 >>
Hereinafter, a pinhole detection device, a pinhole detection method, and a MEA production method according to Embodiment 2 of the present invention will be described with reference to FIGS. 1, 5, and 6. FIG. The overall configuration of the pinhole detection device of the present embodiment is the same as the overall configuration of the pinhole detection device of the first embodiment shown in FIG. Hereinafter, only different parts will be described.
The pinhole detection device according to the second embodiment is different from the first embodiment only in the illumination light source 5, the illumination wavelength filter 6, and the light reception wavelength filter 11. The illumination light source 5 according to the second embodiment is a halogen lamp, and the illumination wavelength filter 6 is a filter that passes only light having a wavelength of 745 nm to 755 nm. The inspection object is irradiated with visible light having a wavelength band of 745 to 755 nm as the illumination light 8. The light receiving wavelength filter 11 is a filter that passes only light having a wavelength of 780 nm to 840 nm.
[0034]
The reason for such a configuration and the advantages compared to the first embodiment will be described with reference to FIGS.
In the first embodiment, the catalyst layer 3 is a black non-transparent substance in which a catalyst such as platinum is mixed in a conductor such as carbon, and when excited by ultraviolet light, the light emission is as shown in FIG. Was small enough. However, the catalyst layer 3 is an important factor influencing the performance of the fuel cell, and has been improved. The main point of improvement is to change the raw materials of the catalyst and the conductor. When the raw material of the catalyst layer 3 is changed, the raw material may generate strong fluorescence.
As shown in the catalyst 2 in FIG. 5, the catalyst layer 3 may generate an amount of fluorescent light close to the amount of light emitted from the polymer film 2. In the characteristics of FIG. 5, it is difficult to discriminate the polymer film 2 from the pinhole 1 where the polymer film 2 does not exist. In this case, it is difficult to detect a pinhole with the method of the first embodiment.
[0035]
As a phenomenon in which a substance reacts with excitation light and the wavelength of light shifts to a longer wavelength side, there is a phenomenon called Raman scattering, apart from fluorescence. A characteristic of Raman scattering is that a peak of light emission appears in a narrow wavelength range inherent to a substance, not in a wide wavelength range like fluorescence. Generally, Raman scattering is likely to occur when the wavelength of the excitation light is equal to or longer than visible light.
[0036]
The graph in FIG. 6 is data obtained by irradiating the polymer film 2 and the catalyst layer 3 with visible light having a wavelength of 750 nm as excitation light and measuring the respective spectral characteristics using a spectrophotometer.
In the graph of FIG. 6, the data of the polymer film 2 is an actually measured value, and the data of the catalyst layer 3 is a predicted value. In the case of Raman scattering, since it is impossible in principle that another substance has a peak at the same place, as shown in the figure, it has a peak at a place where the wavelength is different.
Therefore, as shown in FIG. 6, by using the light receiving wavelength filter 11 that passes only light having a wavelength of 780 nm to 840 nm, the polymer film 2 and the pinhole 1 where the polymer film 2 does not exist can be provided. Can be discriminated at a high S / N ratio.
According to the method of the second embodiment, the raw material of the catalyst layer 3 is changed for the purpose of improvement, and even when the catalyst layer 3 generates a slightly stronger fluorescence due to ultraviolet light, the pinhole 1 existing in the polymer film 2 is reliably detected. It is possible to do.
[0037]
In the present embodiment, a halogen lamp is used as the illumination light source 5 for the purpose of cost reduction, but a laser may be used. When a laser is used, the wavelength range of the light source itself is narrow, so that the illumination wavelength filter 6 may not be necessary.
In the present embodiment, 750 nm is used as the wavelength of light emitted from the illumination light source 5 through the illumination wavelength filter 6. Since Raman scattering occurs from visible light to near infrared light, the illumination wavelength may be visible light (about 400 nm to about 750 nm) or near infrared light (wavelength is about 750 nm to about 2500 nm). When the illumination wavelength is changed, the pass band of the light receiving wavelength filter 11 needs to be changed accordingly.
[0038]
The MEA is manufactured by using the polymer membrane 2 in which the pinhole inspection of the polymer membrane for the fuel cell is performed by the method described in this embodiment and the pinhole 1 having a diameter of 1 μm or more is not present. I do. Thereby, the non-defective rate of the MEA can be greatly improved. As compared with a case where a defect of a polymer film is found in a later step, a man-hour loss in production can be greatly reduced.
[0039]
<< Embodiment 3 >>
Third Embodiment A pinhole detection device, a pinhole detection method, and a MEA production method according to a third embodiment of the present invention will be described with reference to FIGS.
FIG. 7 is a diagram illustrating a configuration of a pinhole detection device according to the third embodiment. In FIG. 7, the same blocks as those of the pinhole detection device of the first embodiment are denoted by the same reference numerals. Description of the same blocks as in the first embodiment will be omitted, and only different blocks will be described. The difference from the first embodiment is that an X-ray source 71 is provided in place of the illumination light source 5, the illumination wavelength filter 6, and the light projecting lens 7 in the first embodiment. The point is that a line filter 72, an X-ray scintillator 73, and a CCD camera 74 are provided.
[0040]
When a substance is irradiated with X-rays, part of the X-rays absorbed by the substance is emitted as fluorescent X-rays having specific energy (wavelength) depending on the type of each element. This fluorescent X-ray is visualized by the X-ray scintillator 73 and detected by the CCD camera 74. The wavelength of the fluorescent X-ray is a value unique to the substance. In the pinhole detection device according to the third embodiment, the presence or absence of a pinhole is detected by installing an X-ray filter 72 that allows only the wavelength range unique to this substance to pass therethrough, in front of the X-ray scintillator 73, and Output as an image.
[0041]
The advantage of inspecting a pinhole using X-rays will be described with reference to FIG. FIG. 8 is a diagram illustrating spectral characteristics when continuous X-rays are irradiated on the polymer film 2 and the catalyst layer 3. Due to the polymer film 2, fluorescent X-rays having a sharp peak near the wavelength of about 0.3 ° are generated. An X-ray filter 72 that allows fluorescent X-rays of this wavelength to pass therethrough is manufactured and installed from a metal such as nickel. The pinhole detector 13 receives image data detected by the CCD camera 74 and detects a pinhole. With this configuration, it is possible to discriminate the polymer film 2 from the pinhole 1 where the polymer film 2 does not exist at a high S / N ratio.
[0042]
The MEA is manufactured by using the polymer membrane 2 in which the pinhole inspection of the polymer membrane for the fuel cell is performed by the method described in this embodiment and the pinhole 1 having a diameter of 1 μm or more is not present. I do. Thereby, the non-defective rate of the MEA can be greatly improved. As compared with a case where a defect of a polymer film is found in a later step, a man-hour loss in production can be greatly reduced.
[0043]
In the above embodiment, pinhole detection of the polymer membrane of the MEA of the fuel cell manufactured by the coating method was performed. The application object of the present invention is not limited to this. For example, a transparent or translucent polymer film may be inspected in a single state, and a pinhole existing there may be detected. In this case, the light source and the light receiving unit may be arranged on the same side with respect to the transparent or translucent polymer film to be inspected, or the light source and the light receiving unit may be transparent or semi-transparent to be inspected. A configuration in which a transparent polymer film is interposed may be used. The inspection object may be non-transparent as long as the loss of the substance can be detected by any of the above methods.
The present invention is also applicable to detecting a pinhole in a thin film formed on the surface of a thick object.
In the embodiment of the present invention, the test object is a polymer film. However, the present invention is not limited to this. A single thin film or a multilayer film may be used.
[0044]
【The invention's effect】
As described above, according to the pinhole detection method of the present invention, the film is irradiated with light that reacts with the constituent material of the film to be inspected as irradiation light, and the film is generated in response to the light. Of the light, only light in a specific wavelength range is detected, and a pinhole is inspected based on the detected light amount.
According to the present invention, there is obtained an advantageous effect that a pinhole detecting device and a pinhole detecting method capable of accurately detecting a pinhole of several μm generated in a polymer film can be realized.
ADVANTAGE OF THE INVENTION According to this invention, the advantageous effect that several micrometers pinhole which exists in the film | membrane of the transparent or translucent test object existing on a non-transparent film | membrane can be detected accurately.
[0045]
According to the present invention, there is obtained an advantageous effect that a MEA production method by a coating method can be realized in which the number of repair steps in a subsequent step is significantly reduced. According to the present invention, an inexpensive fuel cell can be realized.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a pinhole detection device according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of an image including a pinhole output by the pinhole detection device according to the first embodiment of the present invention.
FIG. 3 is a diagram showing an operation of inspecting the entire surface of the inspection object by the pinhole detection device according to the first embodiment of the present invention
FIG. 4 is a graph showing a wavelength distribution of fluorescence emitted when a polymer film and a catalyst are irradiated with ultraviolet light.
FIG. 5 is a graph showing a wavelength distribution of fluorescence emitted when a polymer film and two kinds of catalysts are irradiated with ultraviolet light.
FIG. 6 is a graph showing a wavelength distribution of Raman scattering generated when a polymer film and a catalyst are irradiated with visible light.
FIG. 7 is a diagram showing a configuration of a pinhole detection device according to a third embodiment of the present invention.
FIG. 8 is a graph showing a fluorescent X-ray wavelength distribution generated when the polymer film and the catalyst are irradiated with X-rays.
[Explanation of symbols]
1 Pinhole
2 Polymer film
3 catalyst layer
4 Film base
5 Illumination light source
6. Illumination wavelength filter
7 Floodlight lens
8 Illumination light
9 Light generated by substances
10 Receiving lens
11 Reception wavelength filter
12 Optical sensor
13 Pinhole detector
14 Monitor TV
15 Control unit
16 X axis drive unit
17 Y axis drive unit
18 Work chuck
19 X axis
20 Y axis
71 X-ray source
72 X-ray filter
73 X-ray scintillator
74 CCD camera
132 Image processing unit
133 Image judgment unit

Claims (8)

Irradiating the polymer membrane with irradiation light,
Receives only light of a specific wavelength out of the light generated from the polymer film,
A pinhole detection method, wherein the presence or absence of a pinhole in the polymer film is detected based on the amount of the received light. Irradiate the inspection object with ultraviolet light,
The inspection object receives only light having a wavelength near the wavelength at which the amount of fluorescence generated in response to the ultraviolet light reaches a peak,
A pinhole detection method, wherein the presence or absence of a pinhole in the inspection object is detected based on the amount of the received light. Irradiate the inspection object with visible light,
The inspection object receives only light having a wavelength near a wavelength at which the amount of light generated by causing Raman scattering by the visible light becomes a peak,
A pinhole detection method, wherein the presence or absence of a pinhole in the inspection object is detected based on the amount of the received light. Irradiating the inspection object with X-rays,
The inspection object receives only X-rays having a wavelength near a wavelength at which the intensity of the fluorescent X-ray generated by the reaction with the X-ray becomes a peak,
A pinhole detection method, wherein the presence or absence of a pinhole in the inspection object is detected based on the received X-rays. 5. The pinhole detecting method according to claim 2, wherein the inspection object is a polymer film for a fuel cell. The pinhole detection method according to claim 1, wherein the polymer film is a perfluorosulfonic acid film. 7. The method according to claim 1, wherein the irradiation light, the ultraviolet light, the visible light, or the X-ray is scanned relative to the inspection object or the polymer film. Pinhole detection method. A predetermined material is applied on the base to form an anode catalyst layer,
A polymer film is formed by applying another predetermined material thereon,
The presence or absence of a pinhole in the polymer film is inspected by the pinhole detection method according to any one of claims 1 to 7,
A method for producing a membrane electrode assembly, characterized in that a cathode catalyst layer is formed by applying another predetermined material thereon only when judged as non-defective by the inspection.

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