Method for manufacturing a hydrogen gas barrier coating

Abstract

The present invention provides a method for manufacturing a hydrogen gas barrier coating that improves the hydrogen gas barrier function. [Solution] In the method for manufacturing a hydrogen gas barrier coating, a substrate containing an oligomer is prepared. The method for manufacturing a hydrogen gas barrier coating also includes heating the substrate to a temperature above the glass transition temperature Tg of the substrate and below Tg+60°C (the temperature obtained by adding 60°C to the glass transition temperature), and forming a hydrogen gas barrier film on the heat-treated substrate.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a hydrogen gas barrier coating.

Background Art

[0002] Conventionally, as described in Patent Document 1, a gas barrier laminate including a resin substrate, an undercoat layer laminated on at least one side of the resin substrate, and a transparent oxide film layer laminated on the undercoat layer is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A hydrogen gas barrier film may be formed on the resin substrate of the gas barrier laminate as described in Patent Document 1. When the hydrogen gas barrier film is formed on the resin substrate, the temperature of the resin substrate increases. Further, the resin substrate contains oligomers. An oligomer is a polymer having a molecular weight lower than that of the material of the resin substrate. Furthermore, the glass transition temperature of the oligomer is lower than the glass transition temperature of the material of the resin substrate. Therefore, when the hydrogen gas barrier film is formed on the resin substrate as described in Patent Document 1, the oligomers contained in the resin substrate are deformed due to the increase in the temperature of the resin substrate. When the oligomers contained in the resin substrate are deformed, the hydrogen gas barrier film being formed on the resin substrate follows the deformation of the oligomers. For this reason, the stress of the hydrogen gas barrier film being formed on the resin substrate increases. When the stress of the hydrogen gas barrier film increases, cracks are likely to occur in the hydrogen gas barrier film. When cracks occur in the hydrogen gas barrier film, it becomes a hydrogen permeation path, and thus the hydrogen gas barrier function deteriorates.

[0005] The purpose of this disclosure is to provide a method for manufacturing a hydrogen gas barrier coating that improves the hydrogen gas barrier function. [Means for solving the problem]

[0006] The invention described in claim 1 is a method for manufacturing a hydrogen gas barrier coating, comprising: heating a substrate (10) containing an oligomer to a temperature (Tb) of the substrate at or above the glass transition temperature (Tg) and at or below the glass transition temperature plus 60°C (Tg+60°C); and forming a hydrogen gas barrier film (20) on the heat-treated substrate.

[0007] As a result, the oligomers contained in the substrate are deformed before the hydrogen gas barrier film is formed. Because the oligomers contained in the substrate are deformed beforehand, the deformation of the oligomers during the formation of the hydrogen gas barrier film is suppressed. Therefore, the increase in stress in the hydrogen gas barrier film that follows the deformation of the oligomers during film formation is suppressed. Consequently, the occurrence of cracks in the hydrogen gas barrier film is suppressed. Thus, the hydrogen gas barrier function is improved.

[0008] The reference numerals in parentheses attached to each component indicate an example of the correspondence between that component and the specific components described in the embodiments described later. [Brief explanation of the drawing]

[0009] [Figure 1] A cross-sectional view of a hydrogen gas barrier coating manufactured by the hydrogen gas barrier coating manufacturing method of the embodiment. [Figure 2] A flowchart illustrating the manufacturing method of a hydrogen gas barrier coating. [Figure 3] The figure and table show the relationship between the presence or absence of a hydrogen gas barrier film, the hydrogen permeability coefficient, the change in maximum height roughness, and the absolute value of that change in Examples 1-3, Comparative Examples, and Reference Examples 1-2. [Figure 4] A graph summarizing the relationship between maximum height roughness and the change in maximum height roughness in Examples 1-3 and the comparative example. [Modes for carrying out the invention]

[0010] The embodiments will be described below with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be denoted by the same reference numeral, and their descriptions will be omitted.

[0011] By using the manufacturing method for the hydrogen gas barrier coating of this embodiment, the hydrogen gas barrier function of the hydrogen gas barrier coating is improved. First, the hydrogen gas barrier coating will be described.

[0012] As shown in Figure 1, the hydrogen gas barrier coating comprises a substrate 10 and a hydrogen gas barrier film 20.

[0013] The base material 10 is a component that is not intended to be permeable to hydrogen gas, or it is used to suppress the movement of hydrogen gas to a component located on the opposite side of the space containing hydrogen gas from the base material 10. An example of the former is the tank wall in which hydrogen gas is stored in a hydrogen gas tank. An example of the latter is the film material in a hydrogen gas barrier film. The material of the base material 10 can be any material that can form the hydrogen gas barrier film 20 described later, for example, a resin material such as PEN. The shape of the base material 10 is arbitrary and can be a three-dimensional structure or a film. The thickness of the base material 10 is arbitrary and is, for example, 0.1 mm. PEN is an abbreviation for Polyethylene Naphthalate.

[0014] Furthermore, the base material 10 is formed from a resin material such as polyethylene naphthalate and therefore contains an oligomer. An oligomer is a polymer with a molecular weight lower than that of the resin material.

[0015] The hydrogen gas barrier film 20 is formed on one surface 12 of the substrate 10, thereby covering at least a portion of the substrate 10. The hydrogen gas barrier film 20 also contains a metal oxide film such as aluminum oxide. As a result, the hydrogen gas barrier coating has a hydrogen gas barrier function. Furthermore, as will be described later, to suppress a decrease in the hydrogen gas barrier function, the thickness of the hydrogen gas barrier film 20 is preferably between 20 nm and 60 nm.

[0016] As described above, the hydrogen gas barrier coating is constructed as described. Next, a method for manufacturing the hydrogen gas barrier coating having the above configuration will be explained with reference to the flowchart in Figure 2.

[0017] In step S100, the substrate 10 is prepared. In step S102, following step S100, the substrate temperature Tb is heated using a furnace or the like to a temperature that is above the glass transition temperature Tg of the substrate 10 and below the glass transition temperature Tg plus 60°C, i.e., Tg ≤ Tb ≤ Tg + 60°C. In this state, the substrate 10 prepared in step S100 is heat-treated. At this time, the pressure inside the furnace is, for example, atmospheric pressure. The heating time for the substrate 10 is, for example, 1 hour. The substrate temperature Tb is the temperature of the substrate 10. The glass transition temperature Tg is the temperature at the boundary between the glass state and the rubber state of the resin. For example, the glass transition temperature Tg of polyethylene naphthalate is 120°C. The pressure inside the furnace and the heating time for the substrate 10 are set by experimentation or simulation so that the oligomers contained in the substrate 10 are deformed in advance before the formation of the hydrogen gas barrier film 20 described later.

[0018] In step S104 following step S102, a hydrogen gas barrier film 20 is formed on the substrate 10 heat-treated in step S102. For example, the hydrogen gas barrier film 20 is formed using thermal ALD. The substrate temperature Tb when the hydrogen gas barrier film 20 is being formed is, for example, set to 80°C. The source gas is, for example, trimethylaluminum. The reaction gas is, for example, water vapor. Thereby, a hydrogen gas barrier film 20 of aluminum oxide is formed. Thereby, a hydrogen gas barrier coating including the substrate 10 and the hydrogen gas barrier film 20 is completed. Note that ALD is an abbreviation for Atomic Layer Deposition. Thermal ALD refers to ALD other than plasma ALD.

[0019] Here, when the hydrogen gas barrier film 20 is formed on the substrate 10 that has not been heat-treated in step S102, the absolute value of the change amount of the maximum height roughness of the hydrogen gas barrier coating before and after film formation is defined as the first change amount |ΔRz1|. And the first change amount |ΔRz1| is preferably 20 nm or more.

[0020] Furthermore, here, when the hydrogen gas barrier film 20 is formed in step S104 on the substrate 10 heat-treated in step S102, the absolute value of the change amount of the maximum height roughness of the hydrogen gas barrier coating before and after film formation is defined as the second change amount |ΔRz2|. And the second change amount |ΔRz2| is preferably 10 nm or less.

[0021] As described above, a hydrogen gas barrier coating is manufactured using the manufacturing method of the present embodiment. Next, examples of the manufacturing method of the hydrogen gas barrier coating will be described in comparison with comparative examples.

[0022] First, a plate-shaped polyethylene naphthalate with a thickness of about 0.1 mm is prepared as the substrate 10. From the substrate 10 made of this polyethylene naphthalate, a hydrogen gas barrier coating is formed using the above manufacturing method. At this time, the film thickness of the hydrogen gas barrier film 20 is set to 40 nm.

[0023] Figure 3 shows the measurement results of the hydrogen permeability coefficient when the hydrogen gas barrier film 20 is deposited by changing the presence or absence of the hydrogen gas barrier film 20, the presence or absence of heat treatment of the substrate 10, and the substrate temperature Tb. The hydrogen permeability coefficient is evaluated using a measurement method based on the JIS standard (JIS_K_7126-1). Specifically, using a device that can control the pressure in the spaces on both the upper and lower sides of the sample to be evaluated, hydrogen gas is introduced into the upper space and the space pressure is controlled, and the lower space is reduced to a near-vacuum state, and the amount of hydrogen permeated from the upper space to the lower space is measured. Under these conditions, the hydrogen permeability coefficient is obtained by multiplying the amount of hydrogen permeated by the thickness of the substrate 10 and the hydrogen gas barrier film 20. Since the thickness of the hydrogen gas barrier film 20 is sufficiently small compared to the thickness of the substrate 10, the hydrogen permeability coefficient is generally expressed as the amount of hydrogen permeated multiplied by the thickness of the substrate 10.

[0024] As shown in Figure 3, in Reference Example 1, the hydrogen permeability coefficient was measured in the case where the substrate 10 was heat-treated at a substrate temperature Tb of 150°C, and no hydrogen gas barrier film 20 was formed on the heat-treated substrate 10. As a result, the hydrogen permeability coefficient for Reference Example 1 was 2.9 × 10⁻⁶. -16 It was mol / msPa.

[0025] As a reference example 2, the hydrogen permeability coefficient was measured in the case where neither the heat treatment of the substrate 10 nor the deposition of the hydrogen gas barrier film 20 was performed, i.e., when the substrate 10 was not treated in any way. As a result, the hydrogen permeability coefficient in reference example 2 was 3.4 × 10⁻⁶. -16 It was mol / msPa.

[0026] As a comparative example, the hydrogen permeability coefficient was measured when the substrate 10 was heat-treated at a substrate temperature Tb of 80°C, and a hydrogen gas barrier film 20 was formed on the heat-treated substrate 10. As a result, the hydrogen permeability coefficient of the comparative example was 1.4 × 10⁻⁶. -16The pressure was mol / msPa. Furthermore, for the comparative example, the maximum height roughness of the surface of the substrate 10 on which the hydrogen gas barrier film 20 was deposited was measured using an AFM before the hydrogen gas barrier film 20 was deposited. Additionally, for the comparative example, the maximum height roughness of the deposited hydrogen gas barrier film 20 was measured using an AFM after the film was deposited. For the comparative example, the maximum height roughness of the hydrogen gas barrier coating before and after the deposition of the hydrogen gas barrier film 20 was measured, and the change in maximum height roughness was -54 nm. Therefore, the second change |ΔRz2| for the comparative example was 54 nm. In Figure 3, the change in maximum height roughness of the hydrogen gas barrier coating before and after the deposition of the hydrogen gas barrier film 20 is shown as ΔRz2. AFM stands for Atomic Force Microscope.

[0027] In Example 1, the hydrogen permeability coefficient was measured when the substrate 10 was heat-treated at a substrate temperature Tb of 120°C, and a hydrogen gas barrier film 20 was formed on the heat-treated substrate 10. As a result, the hydrogen permeability coefficient of Example 1 was 6.5 × 10⁻⁶. -17 The concentration was mol / msPa. Furthermore, for Example 1, the maximum height roughness of the hydrogen gas barrier coating before and after the deposition of the hydrogen gas barrier film 20 was measured using an AFM, and the change in the maximum height roughness was -9 nm. Therefore, the second change |ΔRz2| for Example 1 was 9 nm.

[0028] In Example 2, the hydrogen permeability coefficient was measured when the substrate 10 was heat-treated at a substrate temperature Tb of 150°C, and a hydrogen gas barrier film 20 was formed on the heat-treated substrate 10. As a result, the hydrogen permeability coefficient in Example 2 was 1.9 × 10⁻⁶. -17 The concentration was mol / msPa. Furthermore, in Example 2, the maximum height roughness of the hydrogen gas barrier coating before and after the deposition of the hydrogen gas barrier film 20 was measured using an AFM, and the change in the maximum height roughness was -7 nm. Therefore, the second change |ΔRz2| for Example 2 was 7 nm.

[0029] In Example 3, the hydrogen permeability coefficient was measured when the substrate 10 was heat-treated at a substrate temperature Tb of 180°C, and a hydrogen gas barrier film 20 was formed on the heat-treated substrate 10. As a result, the hydrogen permeability coefficient in Example 3 was 2.4 × 10⁻⁶. -17 The concentration was mol / msPa. Furthermore, for Example 3, the maximum height roughness of the hydrogen gas barrier coating before and after the deposition of the hydrogen gas barrier film 20 was measured using an AFM, and the change in the maximum height roughness was 7 nm. Therefore, the second change |ΔRz2| for Example 3 was 7 nm.

[0030] Here, the hydrogen permeability coefficient is a coefficient that indicates how much hydrogen permeates, so a lower value means that the hydrogen gas barrier function is higher. The glass transition temperature Tg of polyethylene naphthalate used in the resin material of substrate 10 is 120°C.

[0031] Furthermore, we compare here a comparative example in which the substrate 10 was heat-treated at 80°C, where the substrate temperature Tb is below the glass transition temperature Tg, with Examples 1, 2, and 3 in which the substrate 10 was heat-treated at 120°C or higher (glass transition temperature Tg) and 180°C or lower (Tg + 60°C).

[0032] Furthermore, the hydrogen permeability coefficients of Examples 1, 2, and 3 were all smaller than those of the comparative example. Therefore, the hydrogen gas barrier coatings of Examples 1, 2, and 3 exhibited high hydrogen gas barrier functionality.

[0033] Furthermore, the glass transition temperature Tg of the oligomer contained in the substrate 10 is lower than the glass transition temperature Tg of the resin material of the substrate 10. Therefore, in Examples 1, 2, and 3, where the substrate 10 is heat-treated at a substrate temperature Tb of 120°C or higher (glass transition temperature Tg) and 180°C or lower (Tg + 60°C), the oligomer contained in the substrate 10 is deformed before the hydrogen gas barrier film 20 is formed. Because the oligomer contained in the substrate 10 is deformed beforehand, the deformation of the oligomer during the formation of the hydrogen gas barrier film 20 is suppressed. Therefore, the increase in stress in the hydrogen gas barrier film 20 that follows the deformation of the oligomer during film formation is suppressed. Consequently, the occurrence of cracks in the hydrogen gas barrier film 20 is suppressed. Thus, in Examples 1, 2, and 3, where the substrate 10 is heat-treated at a substrate temperature Tb of 120°C or higher (glass transition temperature Tg) and 180°C or lower (Tg + 60°C), the hydrogen gas barrier function is improved.

[0034] As described above, by using the manufacturing method for the hydrogen gas barrier coating of this embodiment, the hydrogen gas barrier function of the hydrogen gas barrier coating is improved. Furthermore, the manufacturing method for the hydrogen gas barrier coating of this embodiment also provides the following effects.

[0035] [1] Here, the larger the first change |ΔRz1|, the greater the degree of deformation of the oligomer of the substrate 10 during the deposition of the hydrogen gas barrier film 20 on the substrate 10 which has not been heat-treated.

[0036] Furthermore, in the method for manufacturing the hydrogen gas barrier coating of this embodiment, the oligomers contained in the substrate 10 are pre-deformed by heat treatment of the substrate 10 before the hydrogen gas barrier film 20 is formed. For this reason, the method for manufacturing the hydrogen gas barrier coating of this embodiment is advantageous for substrates 10 in which the first change amount |ΔRz1| is 20 nm or more, that is, for substrates 10 in which the degree of deformation of the oligomers contained in the substrate 10 is relatively large. Therefore, it is preferable that the first change amount |ΔRz1| is 20 nm or more.

[0037] [2] Here, as the second change |ΔRz2| is small, the degree of deformation of the oligomers contained in the substrate 10 during the deposition of the hydrogen gas barrier film 20 on the heat-treated substrate 10 is small.

[0038] Therefore, as shown in Figure 4, it is preferable that -10 nm ≤ ΔRz2 ≤ 10 nm, that is, that the second change amount |ΔRz2| is 10 nm or less. In Figure 4, Rz is the maximum height roughness. ΔRz2 corresponds to ΔRz2 in Figure 3 and is the change in the maximum height roughness of the hydrogen gas barrier coating before and after film formation.

[0039] As a result, the degree of deformation of the oligomers contained in the substrate 10 is relatively small during the deposition of the hydrogen gas barrier film 20. Therefore, the increase in stress in the hydrogen gas barrier film 20 that follows the deformation of the oligomers during deposition is suppressed. Consequently, the occurrence of cracks in the hydrogen gas barrier film 20 is suppressed. Thus, the deterioration of the hydrogen gas barrier function of the hydrogen gas barrier coating is suppressed.

[0040] [3] The hydrogen gas barrier film 20 contains aluminum oxide. This allows the hydrogen gas barrier film 20 to be formed relatively easily and inexpensively.

[0041] [4] Here, when the thickness of the hydrogen gas barrier film 20 is less than 20 nm, the hydrogen gas barrier function is low because the hydrogen gas barrier film 20 is relatively thin, and therefore may not be acceptable. Furthermore, when the thickness of the hydrogen gas barrier film 20 is greater than 60 nm, the stress on the hydrogen gas barrier film 20 increases. When the stress on the hydrogen gas barrier film 20 increases, cracks are more likely to occur in the hydrogen gas barrier film 20. These cracks become hydrogen permeation pathways, so the hydrogen gas barrier function deteriorates.

[0042] In contrast, in the method for manufacturing the hydrogen gas barrier coating of this embodiment, it is preferable that the thickness of the hydrogen gas barrier film 20 is 20 nm or more and 60 nm or less.

[0043] This prevents the hydrogen gas barrier film 20 from becoming too thin. Furthermore, because the hydrogen gas barrier film 20 does not become excessively thick, the stress on the film is relatively low, thus suppressing crack formation. Therefore, the deterioration of the hydrogen gas barrier function is suppressed.

[0044] [5] The base material 10 of the hydrogen gas barrier coating contains polyethylene naphthalate. This makes it possible to manufacture the hydrogen gas barrier coating relatively easily and inexpensively.

[0045] [6] A hydrogen gas barrier film 20 is formed using thermal ALD. This makes the hydrogen gas barrier film 20 less prone to pinholes compared to when it is formed by a different method, such as PVD or CVD. As a result, the formation of pinholes that serve as hydrogen permeation pathways is suppressed, and the deterioration of the hydrogen gas barrier function is suppressed. PVD stands for Physical Vapor Deposition. CVD stands for Chemical Vapor Deposition.

[0046] (Other embodiments) This disclosure is not limited to the embodiments described above, and modifications can be made to these embodiments as appropriate. Furthermore, it goes without saying that, in each of the embodiments described above, the elements constituting the embodiment are not necessarily essential, except in cases where they are explicitly stated to be particularly essential or where they are clearly considered essential in principle.

[0047] In the above embodiment, the material of the substrate 10 containing the oligomer is a resin material such as polyethylene naphthalate. However, the material of the substrate 10 containing the oligomer is not limited to polyethylene naphthalate. The material of the substrate 10 containing the oligomer may be a resin material such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and glycol-modified polyethylene terephthalate. Furthermore, the material of the substrate 10 containing the oligomer may be a resin material such as polyamide and polyamide-based resin. In addition, the material of the substrate 10 containing the oligomer may be a resin material such as polycarbonate, polyphenylene sulfide, polyether ether ketone, and polyether ketone.

[0048] In the above embodiment, the hydrogen gas barrier film 20 is a metal oxide film such as aluminum oxide. However, the hydrogen gas barrier film 20 is not limited to being an aluminum oxide film. The hydrogen gas barrier film 20 may be a metal oxide film such as titanium oxide and zirconium oxide. Furthermore, the hydrogen gas barrier film 20 is not limited to being a metal oxide film. The hydrogen gas barrier film 20 may be a metal nitride film or the like.

[0049] In the above embodiment, the method for depositing the hydrogen gas barrier film 20 is thermal ALD. However, the method for depositing the hydrogen gas barrier film 20 is not limited to thermal ALD, and may also be PVD, CVD, etc. [Explanation of Symbols]

[0050] 10 Base material 12 one side 20 Hydrogen gas barrier membrane

Claims

1. A method for manufacturing a hydrogen gas barrier coating, The substrate (10) containing the oligomer is heat-treated by setting its temperature (Tb) to be above the glass transition temperature (Tg) of the substrate and below the glass transition temperature plus 60°C (Tg + 60°C). A hydrogen gas barrier film (20) is formed on the substrate that has undergone the aforementioned heat treatment, A method for producing a hydrogen gas barrier coating containing [the specified material].

2. The method for manufacturing a hydrogen gas barrier coating according to claim 1, wherein the absolute value of the change in the maximum height roughness of the hydrogen gas barrier coating before and after film formation when the hydrogen gas barrier film is formed on the substrate that has not undergone the heat treatment is 20 nm or more.

3. The method for manufacturing a hydrogen gas barrier coating according to claim 1, wherein the absolute value of the change in the maximum height roughness of the hydrogen gas barrier coating before and after film formation when the hydrogen gas barrier film is formed on the heat-treated substrate is 10 nm or less.

4. The method for producing a hydrogen gas barrier coating according to claim 1, wherein the hydrogen gas barrier film comprises aluminum oxide.

5. The method for producing a hydrogen gas barrier coating according to claim 1, wherein the thickness of the hydrogen gas barrier film is 20 nm or more and 60 nm or less.

6. The method for producing a hydrogen gas barrier coating according to claim 1, wherein the substrate comprises polyethylene naphthalate.

7. A method for producing a hydrogen gas barrier coating according to any one of claims 1 to 6, wherein the hydrogen gas barrier film is formed using thermal ALD.

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