Molded article made of rubber material and method for evaluating same

Abstract

This molded article is made of a rubber material that changes color by a reaction with hydrogen gas, wherein the color difference ΔE*ab (CIE1976) before and after exposure to 100% hydrogen gas at a flow rate of 100 mL / min for 1 minute is 10 or more.

Description

Molded article made of rubber material and evaluation method thereof

[0001] This disclosure relates to a technique for detecting hydrogen gas.

[0002] Hydrogen gas is a colorless and odorless gas with explosiveness. Therefore, the technique for detecting hydrogen gas is important. For example, Patent Document 1 discloses a gas detection element that uses a chemochromic pigment that changes color upon reaction with hydrogen gas for detecting hydrogen gas.

[0003] Japanese Patent Application Laid-Open No. 2019-32312

[0004] However, when the degree of color change of the detection material due to the reaction with hydrogen gas is small, it is actually difficult for an operator to visually determine the presence or absence of color change, for example. In view of the above circumstances, one aspect of this disclosure aims to enable an operator to clearly confirm the presence or absence of hydrogen gas visually.

[0005] In order to solve the above problems, a molded article made of a rubber material according to one aspect of this disclosure is a molded article made of a rubber material that changes color upon reaction with hydrogen gas, and the color difference ΔE * ab (CIE1976) is 10 or more before and after the treatment of being exposed to hydrogen gas with a flow rate of 100 mL / min and a concentration of 100% for 1 minute.

[0006] A molded article made of a rubber material according to one aspect of this disclosure contains a rubber material and tungsten oxide supporting platinum, and is a molded article that changes color upon reaction with hydrogen gas. The content of platinum with respect to 100 parts by weight of the rubber material is 0.001 part by weight or more and  0.15 part by weight or less.

[0007] A molded article made of a rubber material according to one aspect of this disclosure contains a rubber material and tungsten oxide supporting platinum, and is a molded article that changes color upon reaction with hydrogen gas. The content of platinum with respect to the mixture of the platinum and the tungsten oxide is 0.1% by weight or more.

[0008] A method for evaluating a molded article made of rubber material according to one aspect of the present disclosure is a method for evaluating a molded article made of rubber material that changes color upon reaction with hydrogen gas, wherein the color difference ΔE of the molded article before and after a treatment in which the article is exposed to hydrogen gas for one minute. * The color change of the rubber molded product is evaluated using ab (CIE 1976).

[0009] This is an explanatory diagram of a molded product made of rubber material in an embodiment. This is a diagram of the test system configuration. This shows the material content and color difference ΔE in each test sample. * This is a chart showing the measured values ​​of ab. Color difference ΔE in the test sample. * This is the result of measuring the time change of ab. Color difference ΔE in the test sample. * This shows the results of measuring the time change of ab. This is a block diagram illustrating the configuration of an evaluation system for evaluating molded products made of rubber material. This is a flowchart of the evaluation process.

[0010] A: Figure 1 of the embodiment is an explanatory diagram of a molded article 10 made of rubber material according to one embodiment of the present disclosure. The molded article 10 made of rubber material of this embodiment is a product (formed article) that changes color upon reaction with hydrogen gas. The operator can detect the presence or absence of hydrogen gas by visually confirming the color change of the molded article 10. In other words, the molded article 10 of this embodiment is used as a product (hydrogen detection agent) for detecting hydrogen gas. The molded article 10 can be used as a sealing device (seal) such as a gasket or packing by being molded into an annular shape, for example. The molded article 10 can also be installed near a joint where multiple pipes are connected, or near a sealing location in a pipe, and used for detecting hydrogen gas. However, the use and form (e.g., shape or size) of the molded article 10 are not limited to the above examples and may be changed as desired.

[0011] In Figure 1, a disc-shaped molded product 10 is shown as an example for convenience, but the shape of the molded product 10 can be arbitrarily selected depending on circumstances such as the application or installation location. For example, a ring-shaped molded product 10 can be used, for example, as a sealing material to seal the gap between a first member and a second member that are facing each other.

[0012] The molded product 10 is made of rubber material and tungsten oxide (WO) supported with platinum (Pt). ３ The rubber material is the base material for the molded product 10. The rubber material is, for example, vinyl methyl silicone rubber (VMQ) or ethylene propylene diene rubber (EPDM). However, various rubber materials such as chloroprene rubber (CR), silicone rubber (SR), acrylic rubber (ACM), urethane rubber (U), polyurethane rubber (PUR), or fluororubber (FKM) can be used as the rubber material.

[0013] As illustrated in Figure 1, tungsten oxide (specifically tungsten trioxide) is a gaschromic material that reversibly changes color through oxidation-reduction reactions. Specifically, upon contact with hydrogen gas, tungsten oxide changes its properties to absorb the red light band component (600 nm to 800 nm) of visible light. Platinum functions as a catalyst to accelerate the color change of tungsten oxide.

[0014] The molded product 10 is manufactured by a kneading process and a molding process. The kneading process is a process of kneading rubber material, a crosslinking agent, platinum, and tungsten oxide, for example, using rollers. In the kneading process, for example, a powder mixture of platinum and tungsten oxide (hereinafter referred to as "mixture") is kneaded into the rubber material. The molding process is a process of molding the molded product 10 into a predetermined shape, for example, by compression molding using a mold. During the molding process, the molded product 10 is vulcanized.

[0015] The inventors of the present invention investigated the relationship between the degree of discoloration of a molded product 10 when exposed to hydrogen gas and the platinum content of the molded product 10. Figure 2 is a diagram of the test system 20 used in the investigation. The test system 20 is a system for exposing a test sample of the molded product 10 (hereinafter referred to as "test sample 11") to hydrogen gas and observing the discoloration of the test sample 11 before and after exposure to hydrogen gas. The test sample 11 is, for example, a disc with a diameter of 13 mm and a thickness of 2 mm.

[0016] As illustrated in Figure 2, the test system 20 comprises an air supply mechanism 21, an observation jig 22, and an imaging device 23. The air supply mechanism 21 is a mechanism that supplies the test gas (hereinafter referred to as "test gas") for the test sample 11 to the observation jig 22. The supply mechanism includes a hydrogen cylinder 211, an adjustment unit 212, a nitrogen cylinder 213, an adjustment unit 214, and a concentration sensor 215.

[0017] The hydrogen cylinder 211 is a container for storing hydrogen gas. The adjustment unit 212 is a mass flow controller that adjusts the flow rate of hydrogen gas supplied from the hydrogen cylinder 211. The nitrogen cylinder 213 is a container for storing nitrogen gas. The adjustment unit 214 is a mass flow controller that adjusts the flow rate of nitrogen gas supplied from the nitrogen cylinder 213. A test gas of any desired flow rate and concentration, obtained by mixing the hydrogen gas adjusted by the adjustment unit 212 and the nitrogen gas adjusted by the adjustment unit 214, is supplied to the observation jig 22. The concentrations of hydrogen gas and nitrogen gas in the test gas are controlled by adjusting the flow rate by the adjustment unit 212 or the adjustment unit 214. The concentration sensor 215 is a sensor that detects the concentration of hydrogen gas in the test gas. By stopping the supply of nitrogen gas with the adjustment unit 214, it is possible to supply a test gas of 100% hydrogen gas to the observation jig 22.

[0018] The observation jig 22 comprises a housing section 221 and a lid section 222. The housing section 221 is a structure with an observation space S formed on its upper surface. The test sample 11 is housed in the observation space S. The lid section 222 is a plate-shaped member made of a transparent material such as resin, and closes the opening of the observation space S. An air supply hole 223 and an exhaust hole 224 are formed in the observation space S. The test gas supplied from the air supply mechanism 21 flows into the observation space S through the air supply hole 223 and is discharged to the outside space through the exhaust hole 224.

[0019] The imaging device 23 is a camera installed on the opposite side of the lid 222 from the observation space S (i.e., above the observation jig 22). The imaging device 23 generates an observation image of the test sample 11 by receiving light that passes through the lid 222 and arrives from the observation space S. By analyzing the observation image, the color difference ΔE of the test sample 11 before and after exposure to the test gas is determined. *ab is calculated.

[0020] Color difference ΔE * ab (CIE1976) (hereinafter simply referred to as "color difference ΔE * ab") is the distance of the chromaticity coordinates in the L * a * b * color space (CIE1976). Specifically, the chromaticity coordinates (L1 * , a1 * , b1 * ) of the test sample 11 before exposure to hydrogen gas and the chromaticity coordinates (L2 * , a2 * , b2 * ) of the test sample 11 after exposure to hydrogen gas are used in the following calculation to calculate the color difference ΔE * ab. ΔE * ab = { (L2 * - L1 * ) 2 + (a2 * - a1 * ) 2 + (b2 * - b1 * ) 2} 1 / 2 As understood from the above formula, the larger the color difference ΔE * ab, the greater the degree of discoloration of the test sample 11 before and after exposure to hydrogen gas can be evaluated.

[0021] Figure 3 is a chart showing the content of the material in each test sample 11 and the measured value of the color difference ΔE * ab. In Figure 3, the numerical values indicating the content are the parts by weight of each constituent material when the weight of the rubber material is 100. The numerical values (2, 0.5) of each test sample 11 corresponding to the item "Pt Nwt% / WO ３ " (N = 0, 0.02, 0.1, 1, 2, 5) in Figure 3 are the parts by weight of the mixture of platinum and tungsten oxide. Also, "Pt Nwt% / WO ３In the notation, the number N represents the weight percentage of platinum in the platinum-tungsten oxide mixture. Therefore, "parts by weight of the mixture × N × 0.01" corresponds to the parts by weight of platinum when the weight of the rubber material is set to 100. In Figure 3, the parts by weight of platinum are also indicated in parentheses.

[0022] The test samples 11 in Comparative Examples 1 to 3 and Examples 1 to 5 in Figure 3 contain silicone rubber (manufactured by Shin-Etsu Chemical Co., Ltd. / X-30-4609-U) as the rubber material, and 2 parts by weight of peroxide crosslinking agent (manufactured by Momentive Performance Materials Japan LLC / TC-8) as the crosslinking agent.

[0023] In the test shown in Figure 3, the test system 20 illustrated in Figure 2 was used to expose the test sample 11 to 100% hydrogen gas at a flow rate of 100 mL / min for 1 minute. Figure 3 shows the color difference ΔE of the test sample 11 before and after exposure to hydrogen gas. * a and b are shown in the diagram.

[0024] In Comparative Examples 1 to 3, the platinum content is 0.0004 parts by weight or less. The color difference ΔE of test sample 11 in Comparative Examples 1 to 3. * ab is 7 or less. Chromatic difference ΔE * When ab is 7 or less, it is difficult to clearly determine whether or not discoloration has occurred by visual inspection of test sample 11.

[0025] Example 1 is a form in which a mixture containing 0.1% by weight of platinum is incorporated into a rubber material at a ratio of 2 parts by weight. That is, the platinum content in Example 1 is 0.002 parts by weight. Color difference ΔE in Example 1 * The measured value of ab is 100.

[0026] Example 2 is a form in which a mixture containing 1% by weight of platinum is incorporated into a rubber material at a ratio of 2 parts by weight. That is, the platinum content in Example 2 is 0.02 parts by weight. Color difference ΔE in Example 2 * The measured value of ab is 45.

[0027] Example 3 is a form in which a mixture containing 2% by weight of platinum is incorporated into the rubber material at a ratio of 0.5 parts by weight. That is, the platinum content in Example 3 is 0.01 parts by weight. Color difference ΔE in Example 3 * The measured value of ab is 47.

[0028] Example 4 is a form in which a mixture containing 2% by weight of platinum is incorporated into a rubber material at a ratio of 2 parts by weight. That is, the platinum content in Example 4 is 0.04 parts by weight. Color difference ΔE in Example 4 * The measured value of ab is 27.

[0029] Example 5 is a form in which a mixture containing 5% by weight of platinum is incorporated into a rubber material at a ratio of 2 parts by weight. That is, the platinum content in Example 5 is 0.1 parts by weight. Color difference ΔE in Example 5 * The measured value of ab is 18.

[0030] Color difference ΔE * If ab is 10 or greater, the presence or absence of discoloration (and consequently the presence or absence of hydrogen gas) can be clearly determined by visual inspection of the test sample 11. Therefore, in the molded product 10 of the embodiment, the color difference ΔE before and after the treatment in which the product is exposed to hydrogen gas at a flow rate of 100 mL / min and a concentration of 100% for 1 minute is clear. * A configuration in which ab is 10 or more is preferable. With this configuration, the presence or absence of hydrogen gas can be clearly confirmed by a simple method of visually inspecting the molded product 10.

[0031] In a more preferred embodiment, the color difference ΔE before and after treatment involving exposure to 100% hydrogen gas at a flow rate of 100 mL / min for 1 minute. * ab is 40 or greater. For example, in Examples 1 to 3, the color difference ΔE is 40 or greater. * ab is realized. With the above configuration, the presence or absence of discoloration due to reaction with hydrogen gas (and consequently the presence or absence of hydrogen gas) can be determined more clearly by visual inspection by the worker.

[0032] In Comparative Example 1, where the platinum content is 0.0004, the color difference ΔE * In Example 1, where ab is 7 and the platinum content is 0.002, the color difference ΔE* ab is 100. Considering the above results, a form in which the platinum content per 100 parts by weight of rubber material is 0.001 parts by weight or more (more preferably 0.002 parts by weight or more) is preferred.

[0033] Furthermore, comparing Examples 1 to 5, the color difference ΔE increases as the platinum content increases. * A general trend can be observed in which ab decreases. On the other hand, in Example 5, where the platinum content is 0.1 parts by weight, the color difference ΔE * ab is 18. Considering the above results, a form in which the platinum content per 100 parts by weight of rubber material is 0.15 parts by weight or less (more preferably 0.1 parts by weight or less) is preferred.

[0034] On the other hand, the test sample 11 in Comparative Example 4 and Example 6 in Figure 3 contains EPDM (manufactured by Mitsui Chemicals, Inc. / EPT4045H) as a rubber material and 2 parts by weight of peroxide crosslinking agent (manufactured by NOF Corporation / Parkmill D) as a crosslinking agent.

[0035] In Comparative Example 1, which does not contain a mixture of platinum and tungsten oxide, the color difference ΔE * ab is 0. On the other hand, Example 6 is a form in which a mixed material with a platinum content of 2% by weight is incorporated into the rubber material at a ratio of 2 parts by weight. That is, the platinum content in Example 6 is 0.04 parts by weight. Color difference ΔE in Example 6 * The measured value of ab is 22, which is above the value (10) at which discoloration can be clearly recognized.

[0036] Considering the above results, in the molded article 10 of the embodiments, a form in which the platinum content per 100 parts by weight of rubber material is 0.001 parts by weight or more and 0.15 parts by weight or less (Examples 1 to 6) is preferred. With the above forms, compared to forms in which the platinum content is less than 0.001 parts by weight or more than 0.15 parts by weight, the color difference ΔE before and after exposure to hydrogen gas is improved. * Sufficient ab can be secured. Specifically, a color difference ΔE that exceeds the value (10) at which discoloration before and after exposure to hydrogen gas can be clearly recognized. *Ab can be achieved. Furthermore, in this embodiment, since the platinum content is suppressed to 0.15 parts by weight or less, the manufacturing cost of the molded product 10 can be reduced compared to the form in which the platinum content exceeds 0.15 parts by weight.

[0037] In Comparative Examples 1 to 4, the platinum content in the platinum-tungsten oxide mixture is less than 0.1% by weight. On the other hand, in Examples 1 to 6, the platinum content in the platinum-tungsten oxide mixture is 0.1% by weight or more. Considering these results, in the molded article 10 of the embodiment, a form in which the platinum content in the platinum-tungsten oxide mixture is 0.1% by weight or more is preferred. With the above form, the color difference ΔE before and after exposure to hydrogen gas is higher compared to Comparative Examples 1 to 4 in which the platinum content is less than 0.1% by weight. * Sufficient ab can be secured. Specifically, a color difference ΔE that exceeds the value (10) at which discoloration before and after exposure to hydrogen gas can be clearly recognized. * ab can be realized.

[0038] Figures 4 and 5 show the color difference ΔE in test sample 11. * These are the results of measuring the time change of ab. In Figures 4 and 5, the horizontal axis represents time, and the vertical axis represents the color difference ΔE. * It represents ab.

[0039] Figure 4 shows the color difference ΔE for multiple cases where the hydrogen gas flow rate is changed, for Example 1 in Figure 3. * This is the result of measuring ab. In the test shown in Figure 4, the supply of hydrogen gas to the observation space S was started 30 seconds after time 0.

[0040] As can be seen from Figure 4, the color difference ΔE of test sample 11 * ab increases over time from the start of exposure to hydrogen gas. Regardless of the hydrogen gas flow rate, after 60 seconds of exposure to hydrogen gas, the color difference ΔE of the test sample 11 increases. * Figure 4 shows that ab increases to a value close to its maximum value.

[0041] Figure 5 shows the color difference ΔE for multiple cases in which the hydrogen gas concentration in the test gas is changed, for Example 1 in Figure 3. * This is the result of measuring ab. The hydrogen gas concentration in the test gas is adjusted by adjusting the flow rate of hydrogen gas by the adjustment unit 212 and the flow rate of nitrogen gas by the adjustment unit 214. In the test shown in Figure 5, as in the test shown in Figure 4, the supply of hydrogen gas to the observation space S was started 30 seconds after time 0.

[0042] As can be seen from Figure 5, when the hydrogen gas concentration is 25% or higher, the color difference ΔE of the test sample 11 increases after 60 seconds of exposure to the hydrogen gas. * Figure 5 shows that ab increases to a value close to its maximum value.

[0043] Based on the results in Figures 4 and 5, the color difference ΔE of the molded product 10 of the embodiment * As an example of the conditions for evaluating ab as 10 or higher, exposure to 100% hydrogen gas at a flow rate of 100 mL / min for 1 minute was given.

[0044] B: Evaluation method for molded product 10 made of rubber material Figure 6 is a block diagram of an evaluation system 100 for evaluating a molded product 10 made of rubber material. As illustrated in Figure 6, the evaluation system 100 comprises a test system 20 and an information processing device 30. The configuration of the test system 20 is as described above with reference to Figure 2.

[0045] The information processing device 30 is a computer system that evaluates the molded product 10 using the test results from the test system 20. For example, a general-purpose or dedicated information device such as a personal computer can be used as the information processing device 30. The information processing device 30 can communicate with the test system 20 by wire or wireless connection. For example, image data of the observation image of the molded product 10 captured by the imaging device 23 of the test system 20 is transmitted from the test system 20 to the information processing device 30.

[0046] The molded product 10 to be evaluated by the evaluation system 100 contains, for example, a rubber material and platinum-supported tungsten oxide, as illustrated above, and the platinum content per 100 parts by weight of the rubber material is 0.001 parts by weight or more and 0.15 parts by weight or less. Furthermore, the molded product 10 to be evaluated by the evaluation system 100 contains, for example, a rubber material and platinum-supported tungsten oxide, as illustrated above, and the platinum content in the mixture of platinum and tungsten oxide is 0.1% by weight or more. However, the conditions for the test are not limited to the above examples.

[0047] Figure 7 is a flowchart illustrating the specific steps of the evaluation process (hereinafter referred to as the "evaluation process") in which the evaluation system 100 evaluates the molded product 10. The evaluation process involves examining the color difference ΔE of the molded product 10 before and after exposure to hydrogen gas for one minute. * This process evaluates the color change of the molded product 10 using ab (CIE 1976). Note that this evaluation process is an example of a "method for evaluating rubber molded products."

[0048] When the evaluation process is started, the information processing device 30 acquires from the test system 20 the observation image taken by the imaging device 23 before the exposure of the molded product 10 to hydrogen gas, and the observation image taken by the imaging device 23 after the exposure to hydrogen gas (S1). The post-exposure observation image is, for example, an image of the molded product 10 after performing a process in which it is exposed to hydrogen gas at a flow rate of 100 mL / min and a concentration of 100% for 1 minute, as illustrated above. The information processing device 30 uses the pre-exposure observation image and the post-exposure observation image to determine the color difference ΔE before and after exposure to hydrogen gas. * Calculate ab (S2).

[0049] The information processing device 30 controls the color difference ΔE * The color change of the molded product 10 is evaluated according to ab (S3). Specifically, the information processing device 30 evaluates the color difference ΔE * The system determines whether ab is above a threshold. The threshold is set to, for example, "10," which is a value that allows for a clear visual determination of whether or not discoloration has occurred in the molded product 10. That is, the information processing device 30 determines the color difference ΔE of the molded product 10 before and after a treatment in which it is exposed to hydrogen gas at a flow rate of 100 mL / min and a concentration of 100% for 1 minute.* Evaluate whether ab (CIE 1976) is 10 or greater. Note that the color difference ΔE * The threshold value compared to ab may be set to, for example, the aforementioned "40". That is, the information processing device 30 determines the color difference ΔE of the molded product 10 before and after a process in which it is exposed to hydrogen gas at a flow rate of 100 mL / min and a concentration of 100% for 1 minute. * Evaluate whether ab (CIE 1976) is 40 or higher.

[0050] The information processing device 30 controls the color difference ΔE * The results of the evaluation of ab are displayed on a display device (not shown) (S4). That is, the color difference ΔE * The result of determining whether ab is above the threshold value is displayed.

[0051] In the evaluation method illustrated above, the color difference ΔE of the molded product 10 before and after exposure to hydrogen gas is * The color change of the molded product 10 is evaluated using ab (CIE 1976). Therefore, it is possible to easily and appropriately evaluate whether the presence or absence of hydrogen gas can be clearly confirmed by a simple method of visual inspection of the molded product 10 by an operator.

[0052] In the above explanation, the color difference ΔE * An example was given in which the information processing device 30 performs the evaluation of color change using ab (S3), but the color difference ΔE * The evaluation of color change using ab (S3) may be performed by the user of the evaluation system 100 (i.e., the evaluator). For example, the information processing device 30 can determine the color difference ΔE of the molded product 10 before and after exposure to hydrogen gas. * Display ab on the display device. The evaluator will determine the color difference ΔE displayed on the display device. * The color change of the molded product 10 is evaluated using ab. For example, the evaluator evaluates the color difference ΔE * Determine whether ab is above the threshold.

[0053] C: The following are examples of specific modifications that may be added to the embodiments exemplified above. Two or more embodiments may be arbitrarily selected from the following examples and merged as appropriate, provided they do not contradict each other.

[0054] (1) In each of the above-mentioned embodiments, the following conditions were exemplified: [Condition 1] Color difference ΔE before and after treatment in which the sample is exposed to hydrogen gas at a flow rate of 100 mL / min and a concentration of 100% for 1 minute. * [Condition 2] The ab (CIE 1976) is 10 or more. [Condition 3] The platinum content per 100 parts by weight of the rubber material is 0.001 parts by weight or more and 0.15 parts by weight or less.

[0055] Conditions 1 through 3 may be a combination of two or more arbitrarily selected conditions, or each condition may be satisfied individually.

[0056] (2) Condition 2 above includes the following conditions: [Condition 2a] The platinum content is 0.001 parts by weight or more. [Condition 2b] The platinum content is 0.15 parts by weight or less. Only one of the above examples of conditions 2a and 2b may be satisfied.

[0057] (3) A typical example of the molded product 10 is, for example, a molded product manufactured using a mold, but the method of manufacturing the molded product 10 may be arbitrarily changed in this disclosure. For example, the molded product 10 can be manufactured by any processing technique such as extrusion, cutting, rolling or compression.

[0058] D: From the forms exemplified above, the following configurations can be understood, for example.

[0059] A molded article made of a rubber material according to one aspect (Aspect 1) of the present disclosure is a molded article made of a rubber material that changes color upon reaction with hydrogen gas, wherein the color difference ΔE before and after a treatment in which the article is exposed to hydrogen gas at a flow rate of 100 mL / min and a concentration of 100% for 1 minute. * ab (CIE 1976) is 10 or more. In the above embodiment, the color difference ΔE before and after exposure to hydrogen gas is * Since ab (CIE 1976) is 10 or higher, the presence or absence of hydrogen gas can be clearly confirmed by a simple method of visual inspection of the molded product by the worker.

[0060] In a specific example of Embodiment 1 (Embodiment 2), the material contains a rubber material and tungsten oxide supported with platinum, and the amount of platinum per 100 parts by weight of the rubber material is 0.001 parts by weight or more and 0.15 parts by weight or less. In the above embodiment, since the platinum content is 0.001 parts by weight or more and 0.15 parts by weight or less, the color difference ΔE before and after exposure to hydrogen gas is greater compared to the embodiment in which the platinum content is less than 0.001 parts by weight or the embodiment in which the platinum content is greater than 0.15 parts by weight. * Sufficient ab can be secured. Furthermore, since the platinum content is suppressed to 0.15 parts by weight or less, the manufacturing cost of molded products made of rubber can be reduced compared to forms in which the platinum content exceeds 0.15 parts by weight.

[0061] In a specific example of Embodiment 1 or Embodiment 2 (Embodiment 3), the material contains a rubber material and tungsten oxide supported with platinum, and the platinum content in the mixture of platinum and tungsten oxide is 0.1% by weight or more. In the above embodiments, since the platinum content in the mixture of platinum and tungsten oxide is 0.1% by weight or more, the color difference ΔE before and after exposure to hydrogen gas is greater compared to embodiments where the platinum content is less than 0.1% by weight. * ab can be sufficiently secured.

[0062] In any specific example of Embodiments 1 to 3 (Embodiment 4), the color difference ΔE * ab (CIE 1976) is 40 or higher. According to the above embodiment, the presence or absence of discoloration of the molded product due to reaction with hydrogen gas (and consequently the presence or absence of hydrogen gas) can be determined more clearly by visual inspection by the worker.

[0063] A molded article made of rubber material according to one aspect of the present disclosure (Aspect 5) is a molded article containing a rubber material and tungsten oxide supported with platinum, which changes color upon reaction with hydrogen gas, wherein the platinum content per 100 parts by weight of the rubber material is 0.001 parts by weight or more and 0.15 parts by weight or less.

[0064] A molded article made of rubber material according to one aspect of the present disclosure (Aspect 6) is a molded article containing rubber material and platinum-supported tungsten oxide, which changes color upon reaction with hydrogen gas, wherein the platinum content in the mixture of platinum and tungsten oxide is 0.1% by weight or more.

[0065] A method for evaluating a molded article made of rubber material according to one aspect (Aspect 7) of the present disclosure is a method for evaluating a molded article made of rubber material that changes color upon reaction with hydrogen gas, wherein the color difference ΔE of the molded article before and after a treatment in which the article is exposed to hydrogen gas for one minute. * The color change of the molded product is evaluated using ab (CIE 1976). According to the above embodiment, it is possible to easily and appropriately evaluate whether or not the presence or absence of hydrogen gas can be clearly confirmed by a simple method of visually inspecting a molded product made of rubber material by an operator.

[0066] In a specific example of Embodiment 7 (Embodiment 8), the color difference ΔE of the molded product before and after a treatment in which the product is exposed to hydrogen gas at a flow rate of 100 mL / min and a concentration of 100% for 1 minute. * It is determined whether ab (CIE 1976) is 10 or greater. According to the above embodiment, it is possible to appropriately evaluate whether the presence or absence of discoloration of a molded product made of rubber material can be clearly determined by visual inspection. Furthermore, in the specific example of Embodiment 7 (Embodiment 9), the color difference ΔE of the molded product before and after treatment in which it is exposed to hydrogen gas at a flow rate of 100 mL / min and a concentration of 100% for 1 minute. * It is determined whether ab (CIE 1976) is 40 or higher. According to the above embodiment, it is possible to appropriately evaluate whether the presence or absence of discoloration of a molded product made of rubber material can be more clearly determined by visual inspection.

[0067] In any specific example of Embodiments 7 to 9 (Embodiment 10), the molded article made of the rubber material contains the rubber material and tungsten oxide supported with platinum, and the platinum content per 100 parts by weight of the rubber material is 0.001 parts by weight or more and 0.15 parts by weight or less. Also, in any specific example of Embodiments 7 to 10 (Embodiment 11), the molded article made of the rubber material contains the rubber material and tungsten oxide supported with platinum, and the platinum content in the mixture of platinum and tungsten oxide is 0.1% by weight or more.

[0068] 10...Molded product made of rubber material, 11...Test sample, 20...Test system, 21...Air supply mechanism, 211...Hydrogen cylinder, 212...Adjustment unit, 213...Nitrogen cylinder, 214...Adjustment unit, 215...Concentration sensor, 22...Observation jig, 221...Storage unit, 222...Lid unit, 23...Imaging device.

Claims

1. A molded product made of rubber material that changes color upon reaction with hydrogen gas, wherein the color difference ΔE is observed before and after exposure to hydrogen gas at a flow rate of 100 mL / min and a concentration of 100% for 1 minute. * A molded product made of rubber material in which ab (CIE 1976) is 10 or more.

2. A molded article made of the rubber material according to claim 1, comprising a rubber material and tungsten oxide supported with platinum, wherein the amount of platinum per 100 parts by weight of the rubber material is 0.001 parts by weight or more and 0.15 parts by weight or less.

3. A molded article made of the rubber material according to claim 1, comprising a rubber material and tungsten oxide supported with platinum, wherein the platinum content in the mixture of platinum and tungsten oxide is 0.1% by weight or more.

4. The aforementioned color difference ΔE * ab (CIE 1976) is a molded article made of the rubber material of claim 1, wherein ab is 40 or more.

5. A method for evaluating a molded product made of rubber material that changes color upon reaction with hydrogen gas, wherein the color difference ΔE of the molded product before and after a treatment in which the product is exposed to hydrogen gas for 1 minute. * A method for evaluating a molded product made of rubber material, which uses ab (CIE 1976) to evaluate the color change of the molded product.

6. In the evaluation of the color change, the color difference ΔE of the molded product before and after exposure to hydrogen gas at a flow rate of 100 mL / min and a concentration of 100% for 1 minute. * The evaluation method of claim 5 for determining whether ab (CIE 1976) is 10 or more.

7. In the evaluation of the color change, the color difference ΔE of the molded product before and after exposure to hydrogen gas at a flow rate of 100 mL / min and a concentration of 100% for 1 minute. * The evaluation method of claim 5 for determining whether ab (CIE 1976) is 40 or more.

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