Laminated film

Abstract

Provided is a laminated film which includes a porous layer and in which the total content ratio of eluted elements in the porous layer is sufficiently reduced; in other words, deterioration or alteration of the porous layer is suppressed. Provided is a method for producing a laminated film including a porous layer, whereby the total content ratio of eluted elements in the porous layer can be sufficiently reduced; in other words, deterioration or alteration of the porous layer can be suppressed.　A laminated film according to an embodiment of the present invention includes a porous layer, wherein the total content ratio of eluted elements in the porous layer is 20 at.% or less. A method for producing a laminated film according to an embodiment of the present invention is a method for producing a laminated film including a porous layer, and comprises a porous layer formation step, wherein the porous layer formation step includes a precursor layer formation step for forming a specific precursor layer, and a dealloying step for treating the precursor layer under specific conditions.

Description

Laminated Film

[0001] The present invention relates to a laminated film and a method for producing the same, and more particularly to a laminated film including a porous layer and a method for producing the same.

[0002] Laminates including porous layers can be used in a variety of applications. For example, an electrode using a laminated catalyst and a substrate having a porous structure has been reported as an electrode for use in a water electrolysis device (for example, Patent Document 1).

[0003] A known method for forming a porous layer is alloy dealloying. The alloy dealloying method is a method in which an alloy of a leachable element that dissolves in the dealloying solution and a metal other than the leachable element is treated with the dealloying solution. Specifically, the porous layer can be formed by treating a precursor layer containing an alloy of a leachable element that dissolves in the dealloying solution and a metal other than the leachable element with the dealloying solution. By the dealloying method, the leachable element contained in the precursor layer is dissolved into the dealloying solution, and a porous layer is formed.

[0004] Japanese Patent Application Laid-Open No. 2021-45709

[0005] However, conventional porous layers tend to be easily deteriorated or altered.

[0006] The present inventors have investigated the reasons why conventional porous layers are prone to deterioration and alteration. As a result, they have found that the presence of eluted elements in the porous layer affects the deterioration and alteration of the porous layer. They have also found that the deterioration and alteration of the porous layer can be suppressed by reducing the proportion of eluted elements in the porous layer to a predetermined range.

[0007] An object of the present invention is to provide a laminate film including a porous layer in which the total content of eluted elements in the porous layer is sufficiently reduced, in other words, deterioration or alteration of the porous layer is suppressed. Another object of the present invention is to provide a method for producing a laminate film including a porous layer in which the total content of eluted elements in the porous layer can be sufficiently reduced, in other words, deterioration or alteration of the porous layer can be suppressed.

[0008] [1] A laminate film according to an embodiment of the present invention includes a porous layer, and the total content of leachable elements in the porous layer is 20 atomic percent or less. [2] In the laminate film described in [1] above, the leachable elements may include at least one selected from the group consisting of Al, Zn, Ag, and Sn. [3] In the laminate film described in [1] or [2] above, the porous layer may include at least one selected from the group consisting of a metal element other than the leachable elements, a metalloid element, and carbon. [4] In the laminate film described in [3] above, the metal element other than the leachable elements may include at least one selected from the group consisting of Mg, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ce, Pr, Ta, W, Os, Ir, Pt, Au, and Bi. [5] In the laminate film according to [3] or [4] above, the metalloid element may include at least one selected from the group consisting of B, Si, Ge, and Sb. [6] In the laminate film according to any one of [1] to [5] above, the laminate film may include a substrate. [7] In the laminate film according to [6] above, the substrate and the porous layer may be laminated via an adhesive layer. [8] In the laminate film according to [7] above, the adhesive layer may have a thickness of 1 nm to 100 nm. [9] In the laminate film according to [7] or [8] above, the adhesive layer may include at least one selected from the group consisting of base metal elements, metalloid elements, and carbon.

[10] In the laminate film according to [9] above, the base metal element may include at least one selected from the group consisting of Mg, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ce, Pr, Ta, W, and Bi.

[11] In the laminate film according to any one of [6] to

[10] above, the porous layer may be provided on both sides of the substrate.

[12] In the laminate film according to any one of [6] to

[11] above, the surface of the substrate facing the porous layer may include a resin.

[13] A method for producing a laminate film according to an embodiment of the present invention is a method for producing a laminate film including a porous layer, comprising: a porous layer-forming step of forming the porous layer, the porous layer-forming step comprising: a precursor layer-forming step of forming a precursor layer containing an alloy of a leachable element and at least one element selected from the group consisting of a metal element other than the leachable element, a metalloid element, and carbon; and a dealloying step of treating the precursor layer with a dealloying solution at a temperature of 40° C. or higher.

[14] In the method for producing a laminate film according to

[13] above, the leachable element may include at least one element selected from the group consisting of Al, Zn, Ag, and Sn.

[15] In the method for producing a laminate film according to

[13] or

[14] above, the precursor layer may be formed by co-sputtering a first metal target with at least one selected from the group consisting of a second target and a second alloy target, where the first metal target is the eluted element, the second target is at least one selected from the group consisting of a metal element other than the eluted element, a metalloid element, and carbon, and the second alloy target is an alloy composed of at least two selected from the group consisting of a metal element other than the eluted element, a metalloid element, and carbon.

[16] In the method for producing a laminate film according to

[13] or

[14] above, the precursor layer may be formed by sputtering an alloy target, where the alloy target is an alloy composed of the eluted element and at least one selected from the group consisting of a metal element other than the eluted element, a metalloid element, and carbon.

[17] In the method for producing a laminate film according to any one of

[13] to

[16] above, the porous layer may be formed on at least one side of the substrate in the porous layer-forming step.

[18] In the method for producing a laminated film according to the above

[17] , an adhesion layer forming step of forming an adhesion layer on at least one surface of the substrate may be included, and the porous layer forming step may be carried out after the adhesion layer forming step.

[0009] According to the present invention, it is possible to provide a laminate film including a porous layer in which the total content ratio of eluted elements in the porous layer is sufficiently reduced, in other words, deterioration or alteration of the porous layer is suppressed. According to the present invention, it is also possible to provide a method for producing a laminate film including a porous layer in which the total content ratio of eluted elements in the porous layer can be sufficiently reduced, in other words, deterioration or alteration of the porous layer can be suppressed.

[0010] [Terminology] In this specification, when the expression "weight" appears, it may be read as "mass," which is commonly used as an SI unit indicating weight, and vice versa.

[0011] 1. Laminated Film The laminated film according to the embodiment of the present invention includes a porous layer. The laminated film according to the embodiment of the present invention may include any appropriate other layer as long as the effects of the present invention are not impaired.

[0012] The laminate film according to an embodiment of the present invention may include a substrate.

[0013] In an embodiment in which the laminate film according to the present invention includes a substrate, the laminate film according to the present invention may have a porous layer on only one side of the substrate, or may have a porous layer on both sides of the substrate.

[0014] In an embodiment in which the laminate film according to the present invention includes a substrate, the laminate film according to the present invention may have a substrate and a porous layer directly laminated thereon. That is, the laminate film according to the present invention may have a laminate structure in which the substrate and the porous layer are laminated in this order. A representative example of the laminate film according to the present invention according to such an embodiment is a laminate film in which the substrate and the porous layer are laminated in this order.

[0015] In an embodiment in which the laminate film according to the present invention includes a substrate, the laminate film according to the present invention may have the substrate and the porous layer laminated via an adhesive layer. That is, the laminate film according to the present invention may have a laminate structure in which the substrate, the adhesive layer, and the porous layer are laminated in this order. A representative example of the laminate film according to the present invention according to such an embodiment is a laminate film in which the substrate, the adhesive layer, and the porous layer are laminated in this order.

[0016] The total thickness of the laminate film of the present invention may be any appropriate thickness depending on the purpose, as long as the effects of the present invention are not impaired. The total thickness of the laminate film of the present invention may be, for example, 1 μm to 2000 μm, 50 μm to 1400 μm, 100 μm to 1000 μm, 130 μm to 600 μm, 150 μm to 500 μm, 150 μm to 300 μm, or 150 μm to 250 μm. For example, in an embodiment in which a porous layer is provided on only one side of the substrate, the total thickness of the laminate film of the present invention may be 1 μm to 1000 μm, 50 μm to 700 μm, 100 μm to 500 μm, 130 μm to 300 μm, or 150 μm to 250 μm.

[0017] <1-1. Substrate> Any appropriate substrate can be used as the substrate as long as it does not impair the effects of the present invention. The substrate may be composed of a single layer or may be a laminate of two or more layers.

[0018] The thickness of the substrate may be any appropriate thickness depending on the purpose as long as the effects of the present invention are not impaired. The thickness of the substrate is, for example, 1 μm to 1000 μm, or may be 50 μm to 700 μm, 100 μm to 500 μm, 130 μm to 300 μm, or 150 μm to 250 μm.

[0019] The substrate may be any appropriate material depending on the purpose, as long as the effect of the present invention is not impaired.

[0020] Examples of the substrate include resin substrates (e.g., polyethylene terephthalate (PET) substrates and polyimide (PI) substrates), composite substrates containing resin (e.g., Zirfon (registered trademark) manufactured by AGFA), metal substrates (e.g., Cu foil, Ti foil, Ti fibrous body (e.g., Pt-plated Ti fibrous body), Ni porous body), carbon composite materials (e.g., carbon paper, carbon paper on which MPL (Micro Porous Layer) is formed), cation exchange membranes (e.g., Nafion (registered trademark) and hydrocarbon-based electrolyte membranes), anion exchange membranes (e.g., polybenzimidazole (PBI) membranes), semiconductor substrates (e.g., silicon substrates), and glass substrates.

[0021] One embodiment of the substrate is an electrolyte membrane. Examples of electrolyte membranes include composite substrates containing resin (e.g., Zirfon (registered trademark) manufactured by AGFA), cation exchange membranes (e.g., Nafion (registered trademark) and hydrocarbon-based electrolyte membranes), and anion exchange membranes (e.g., polybenzimidazole (PBI) membranes). When the substrate is an electrolyte membrane, the laminate film according to an embodiment of the present invention may be a catalyst composite for water electrolysis (a laminate composite including a porous layer as a catalyst layer and an electrolyte membrane) or a catalyst composite for fuel cells (a laminate composite including a porous layer as a catalyst layer and an electrolyte membrane), and may be a catalyst composite for water electrolysis or a catalyst composite for fuel cells that has excellent durability. When the substrate is an electrolyte membrane, the laminate film according to an embodiment of the present invention may be a catalyst composite for CO electrolysis (e.g., for electrolytic synthesis of formic acid or synthetic fuels) (a laminate composite including a porous layer as a catalyst layer and an electrolyte membrane), and may be a catalyst composite for CO electrolysis that has excellent durability.

[0022] As one embodiment of the substrate, the surface on the porous layer side of the substrate may contain a resin. As the substrate of such an embodiment, any suitable substrate can be adopted as long as it contains a resin component on at least one surface, as long as the effects of the present invention are not impaired. In addition to the above-mentioned resin substrate, the substrate of such an embodiment includes, for example, the above-mentioned composite substrate containing a resin component on at least one surface, a MPL (Micro Porous Layer) composed of a resin formed on carbon paper, a cation exchange membrane containing a resin component on at least one surface, an anion exchange membrane containing a resin component on at least one surface, and a laminated substrate having a resin layer on at least one surface of a non-resin layer (such as a metal layer).

[0023] <1-2. Porous Layer> The thickness of the porous layer may be any appropriate thickness depending on the purpose, as long as the effects of the present invention are not impaired. The thickness of the porous layer is, for example, 1 nm to 3000 nm, or may be 10 nm to 2000 nm, 50 nm to 1500 nm, 100 nm to 1000 nm, or 200 nm to 800 nm.

[0024] The porous layer may be composed of one layer or may be a laminate of two or more layers.

[0025] The porous layer has a porous structure, which increases the surface area of ​​the porous layer and can provide various effects, such as increased gas diffusivity and high catalytic activity.

[0026] In the laminate film according to an embodiment of the present invention, the total content of eluted elements in the porous layer is typically 20 atomic weight percent or less, and may be 18 atomic weight percent or less, 15 atomic weight percent or less, 12 atomic weight percent or less, 10 atomic weight percent or less, 8 atomic weight percent or less, 6 atomic weight percent or less, 4 atomic weight percent or less, 2 atomic weight percent or less, 1 atomic weight percent or less, 0.1 atomic weight percent or less, or even substantially 0 atomic weight percent. In the laminate film according to an embodiment of the present invention, as long as the total content of eluted elements in the porous layer is within the above range, the effects of the present invention can be exhibited and deterioration or alteration of the porous layer can be suppressed.

[0027] The eluted element may be, for example, an element that dissolves in a dealloying solution in a dealloying method of an alloy. In terms of being able to further exhibit the effects of the present invention, the eluted element is preferably at least one element selected from the group consisting of Al, Zn, Ag, and Sn.

[0028] The porous layer may contain at least one element selected from the group consisting of metal elements other than the eluted elements, metalloid elements, and carbon.

[0029] As the metal element other than the elution element, any appropriate metal element can be adopted as long as it does not impair the effects of the present invention. The metal element other than the elution element may be only one type, or two or more types. When the porous layer contains two or more types of metal elements, the two or more types of metals may be an alloy.

[0030] The metal elements other than the eluted elements typically include at least one selected from the group consisting of noble metal elements and base metal elements. The noble metal elements may be one type only, or two or more types. The base metal elements may be one type only, or two or more types.

[0031] Any appropriate noble metal element may be used as long as it does not impair the effects of the present invention, such as at least one selected from the group consisting of Ru, Rh, Pd, Os, Ir, Pt, and Au.

[0032] Any appropriate base metal element may be used as the base metal element as long as it does not impair the effects of the present invention. Examples of the base metal element include metal elements other than noble metal elements, and preferably at least one selected from the group consisting of Mg, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ce, Pr, Ta, W, and Bi.

[0033] As the metalloid element, any appropriate metalloid element can be used as long as it does not impair the effects of the present invention. Examples of the metalloid element include B, Si, Ge, As, Sb, and Te, and preferably at least one element selected from the group consisting of B, Si, Ge, and Sb.

[0034] In order to further exert the effects of the present invention, the total content of metal elements, metalloid elements, and carbon other than the eluted elements in the porous layer is preferably 80 atomic weight % or more, or may be 82 atomic weight % or more, or 85 atomic weight % or more, or 88 atomic weight % or more, or 90 atomic weight % or more, or 92 atomic weight % or more, or 94 atomic weight % or more, or 96 atomic weight % or more, or 98 atomic weight % or more, or 99 atomic weight % or more, or 99.9 atomic weight % or more, or may be substantially 100 atomic weight %.

[0035] The porous layer may contain any other appropriate component within the range that does not impair the effects of the present invention.

[0036] The porous layer can be formed by any appropriate method as long as it does not impair the effects of the present invention. To further enhance the effects of the present invention, the porous layer can be formed, for example, by a dealloying method. Specifically, the porous layer can be formed by treating a precursor layer containing an alloy of a leachable element that dissolves in a dealloying solution and at least one element selected from the group consisting of a metal element, a metalloid element, and carbon other than the leachable element, with a dealloying solution. By the dealloying method, the leachable element contained in the precursor layer is dissolved into the dealloying solution, forming the porous layer.

[0037] [1-2-a. Precursor Layer] The precursor layer typically contains an alloy of a leachable element and at least one selected from the group consisting of a metal element other than the leachable element, a metalloid element, and carbon. Note that the term "alloy" as used herein also includes alloy steel (an alloy of a leachable element and a metalloid element, an alloy of a leachable element and carbon, or an alloy of a leachable element, a metalloid element, and carbon). The leachable element may be of only one type, or two or more types. The metal element other than the leachable element may be of only one type, or two or more types. The metalloid element may be of only one type, or two or more types.

[0038] When the precursor layer contains an alloy of a leachable element and at least one selected from the group consisting of a metal element other than the leachable element, a metalloid element, and carbon, the content ratio of the leachable element to the at least one selected from the group consisting of a metal element other than the leachable element, a metalloid element, and carbon in the precursor layer, expressed as atomic weight percent (at %) of [leachable element]:[total of metal elements other than the leachable element, metalloid element, and carbon], may be, for example, 30:70 to 99.9:0.1, alternatively, 50:50 to 99:1, 60:40 to 98:2, 70:30 to 97:3, 75:25 to 96:4, or 80:20 to 95:5, in terms of atomic weight percent (at %).

[0039] Examples of the eluting element include elements that dissolve in a dealloying solution during alloy dealloying. In order to further enhance the effects of the present invention, the eluting element is preferably at least one element selected from the group consisting of Al, Zn, Ag, and Sn. Therefore, the precursor layer preferably contains an alloy of at least one eluting element selected from the group consisting of Al, Zn, Ag, and Sn and at least one element selected from the group consisting of a metal element, a metalloid element, and carbon other than the eluting element.

[0040] Examples of metal elements other than the eluted elements include at least one selected from the group consisting of Mg, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ce, Pr, Ta, W, Os, Ir, Pt, Au, and Bi.

[0041] The precursor layer can be formed by any appropriate method as long as the effects of the present invention are not impaired. For example, the precursor layer is formed by a vacuum film formation method, specifically, by vapor deposition or sputtering.

[0042] The precursor layer is preferably formed by sputtering, for example, by co-sputtering using multiple targets (sometimes referred to as simultaneous sputtering) or sputtering using an alloy target.

[0043] Any appropriate sputtering conditions may be adopted as long as they do not impair the effects of the present invention. The atmosphere during sputtering may be, for example, a rare gas atmosphere such as argon. The pressure during sputtering may be, for example, 0.1 Pa to 10 Pa. Examples of the discharge method for sputtering include DC discharge, RF discharge, and MF-AC discharge. The sputtering temperature may be set to any appropriate temperature depending on the type of substrate, etc. The sputtering temperature may be, for example, -10°C to 150°C (e.g., sputtering onto a PET substrate), -10°C to 500°C (e.g., sputtering onto a PI substrate), or -10°C to 1000°C (e.g., sputtering onto a metal substrate).

[0044] In an embodiment in which the precursor layer is formed by co-sputtering, the precursor layer is formed, for example, by co-sputtering a first metal target with at least one selected from the group consisting of a second target and a second alloy target.

[0045] The first metal target may be, for example, an eluted element. The first metal target may be one type or two or more types.

[0046] The second target may be, for example, at least one selected from the group consisting of metal elements other than the eluted elements, metalloid elements, and carbon. The second target may be of only one type, or of two or more types.

[0047] The second alloy target may be, for example, an alloy composed of at least two elements selected from the group consisting of metal elements other than the eluted elements, metalloid elements, and carbon. The second alloy target may be of only one type, or of two or more types.

[0048] In an embodiment in which the precursor layer is formed by co-sputtering, the first metal target, the second target, and the second alloy target may be selected and the sputtering conditions may be set as appropriate, for example, as described above, so that the content ratio of the eluted element in the resulting precursor layer to at least one element selected from the group consisting of metal elements other than the eluted element, metalloid elements, and carbon falls within the aforementioned range in atomic weight percentage (at %) of [eluted element]:[total of metal elements other than the eluted element, metalloid elements, and carbon].

[0049] In an embodiment in which the precursor layer is formed by sputtering an alloy target, the alloy target may be an alloy composed of a leaching element and at least one element selected from the group consisting of a metal element other than the leaching element, a metalloid element, and carbon. The alloy target may be one type only, or two or more types.

[0050] In an embodiment in which the precursor layer is formed by sputtering an alloy target, the alloy target may be selected and the sputtering conditions may be set as appropriate, for example, as described above, so that the content ratio of the eluted element in the resulting precursor layer to at least one element selected from the group consisting of metal elements other than the eluted element, metalloid elements, and carbon falls within the aforementioned range in terms of the atomic ratio (at %) of [eluted element]:[total of metal elements other than the eluted element, metalloid elements, and carbon].

[0051] When forming the precursor layer, film formation by sputtering may be performed multiple times for the purpose of adjusting the thickness (especially, adjusting to increase the thickness), etc. Furthermore, the number of targets may be increased for the purpose of adjusting the thickness (especially, adjusting to increase the thickness), etc.

[0052] [1-2-b. Dealloying Method] The porous layer can be formed, for example, by a dealloying method. For example, the porous layer can be formed by treating the precursor layer with a dealloying solution. This dealloying method allows eluted elements contained in the precursor layer to be dissolved into the dealloying solution, thereby forming the porous layer. Any appropriate conditions for the dealloying method can be adopted as long as the treatment with the dealloying solution can be performed at an appropriate temperature, as long as the effects of the present invention are not impaired.

[0053] The dealloying solution for treating the precursor layer may be, for example, any suitable acidic, alkaline, or neutral solution that can be used in a dealloying method. The concentration of the dealloying solution may be any suitable concentration depending on the purpose.

[0054] Examples of the acidic solution include an aqueous solution of hydrochloric acid, an aqueous solution of nitric acid, an aqueous solution of sulfuric acid, an aqueous solution of phosphoric acid, an aqueous solution of acetic acid, and a mixture thereof. Examples of the alkaline solution include an aqueous solution of sodium hydroxide and an aqueous solution of potassium hydroxide.

[0055] The treatment temperature in the dealloying method is, for example, 5° C. or higher, and may be 10° C. or higher, 20° C. or higher, 30° C. or higher, 40° C. or higher, 50° C. or higher, 60° C. or higher, 70° C. or higher, 80° C. or higher, 90° C. or higher, or 100° C. The upper limit of the treatment temperature in the dealloying method is, for example, less than 300° C.

[0056] In the dealloying method, the treatment with the dealloying solution may be carried out under normal pressure or under pressure. As a method for carrying out the treatment under pressure, any appropriate pressurizing method may be adopted as long as it does not impair the effects of the present invention. Such a pressurizing method may, for example, be pressurizing in a pressure-resistant vessel such as an autoclave.

[0057] <1-3. Adhesion Layer> In the laminate film according to an embodiment of the present invention, the substrate and the porous layer may be laminated via an adhesion layer. That is, the laminate film according to an embodiment of the present invention may include a laminate structure in which the substrate, the adhesion layer, and the porous layer are laminated in this order. A representative example of the laminate film of the present invention according to such an embodiment is a laminate film in which the substrate, the adhesion layer, and the porous layer are laminated in this order.

[0058] The thickness of the adhesive layer may be any appropriate total thickness as long as it does not impair the effects of the present invention. In terms of further exhibiting the effects of the present invention, the thickness of the adhesive layer is, for example, 1 nm to 1000 nm, or may be 1 nm to 500 nm, 2 nm to 500 nm, 3 nm to 500 nm, 4 nm to 500 nm, 5 nm to 500 nm, 5 nm to 300 nm, or 5 nm to 200 nm.

[0059] The adhesive layer may be made of one layer or may be a laminate of two or more layers.

[0060] The adhesive layer contains at least one selected from the group consisting of a metal element, a metalloid element, and carbon. The adhesive layer may contain any other appropriate component as long as the effects of the present invention are not impaired.

[0061] As the metal element that can be contained in the adhesive layer, any appropriate metal element can be adopted as long as the effects of the present invention are not impaired. The metal element may be only one type, or may be two or more types. When the adhesive layer contains two or more types of metal elements, the two or more types of metals may be an alloy.

[0062] The metal element typically includes at least one selected from the group consisting of a noble metal element and a base metal element. The noble metal element may be only one type, or two or more types. The base metal element may be only one type, or two or more types.

[0063] Any appropriate noble metal element may be used as long as it does not impair the effects of the present invention, such as at least one selected from the group consisting of Ru, Rh, Pd, Os, Ir, Pt, and Au.

[0064] Any appropriate base metal element may be used as the base metal element as long as it does not impair the effects of the present invention. Examples of the base metal element include metal elements other than noble metal elements, and preferably at least one selected from the group consisting of Mg, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ce, Pr, Ta, W, and Bi.

[0065] As the metalloid element, any appropriate metalloid element can be used as long as it does not impair the effects of the present invention. Examples of the metalloid element include B, Si, Ge, As, Sb, and Te, and preferably at least one element selected from the group consisting of B, Si, Ge, and Sb.

[0066] In one preferred embodiment, the adhesion layer contains at least one selected from the group consisting of a base metal element, a metalloid element, and carbon. In this embodiment, the adhesion layer does not necessarily contain a noble metal element.

[0067] In the laminate film according to an embodiment of the present invention, when a resin substrate (such as a polyethylene terephthalate (PET) substrate) is used as the substrate, it is a preferred embodiment that the adhesion layer contains at least one selected from the group consisting of base metal elements, semi-metal elements, and carbon, in order to further demonstrate the effects of the present invention. On the other hand, in the laminate film according to an embodiment of the present invention, when carbon paper or carbon paper with an MPL (Micro Porous Layer) formed thereon is used as the substrate, the adhesion layer may contain a precious metal element, and therefore it is a preferred embodiment that the adhesion layer contains at least one selected from the group consisting of metal elements (noble metal elements and base metal elements), semi-metal elements, and carbon, in order to further demonstrate the effects of the present invention.

[0068] The adhesion layer can be formed by any appropriate method as long as the effects of the present invention are not impaired. The adhesion layer is typically formed by a vacuum film formation method, for example, by vapor deposition or sputtering.

[0069] Formation by sputtering includes, for example, single target sputtering, co-sputtering (sometimes referred to as simultaneous sputtering), and alloy target sputtering.

[0070] Any appropriate sputtering conditions may be adopted as long as they do not impair the effects of the present invention. The atmosphere during sputtering may be, for example, a rare gas atmosphere such as argon. The pressure during sputtering may be, for example, 0.1 Pa to 10 Pa. Examples of the discharge method for sputtering include DC discharge, RF discharge, and MF-AC discharge. The sputtering temperature may be set to any appropriate temperature depending on the type of substrate, etc. The sputtering temperature may be, for example, -10°C to 150°C (e.g., sputtering onto a PET substrate), -10°C to 500°C (e.g., sputtering onto a PI substrate), or -10°C to 1000°C (e.g., sputtering onto a metal substrate).

[0071] Before sputtering, the sputtering target (typically a substrate) may be cleaned by subjecting it to a plasma treatment, such as ion bombardment. Any appropriate conditions for the plasma treatment may be adopted as long as the effects of the present invention are not impaired.

[0072] The laminate film according to the embodiment of the present invention can be produced by any appropriate method as long as the effects of the present invention are not impaired. In terms of being able to further exhibit the effects of the present invention, the laminate film according to the embodiment of the present invention can be preferably produced by the method described below.

[0073] 2. Method for Producing Laminated Film A method for producing a laminated film according to an embodiment of the present invention is a method for producing a laminated film including a porous layer, and includes a porous layer forming step of forming the porous layer.

[0074] <2-1. Porous Layer Forming Step> The porous layer forming step is a step of forming a porous layer, and in one preferred embodiment, the porous layer is formed on at least one side of the substrate.

[0075] The porous layer forming step includes a precursor layer forming step and a dealloying step.

[0076] [2-1-a. Precursor layer forming step] In the precursor layer forming step, a precursor layer is formed. In one preferred embodiment of the precursor layer forming step, the precursor layer is formed on at least one side of the substrate. The precursor layer may be formed on the substrate, or may be formed on an adhesion layer formed in the adhesion layer forming step, as described below.

[0077] In the precursor layer forming step, a precursor layer is formed containing an alloy of a leaching element and at least one element selected from the group consisting of a metal element other than the leaching element, a metalloid element, and carbon. The leaching element may be only one type, or two or more types. The metal element other than the leaching element may be only one type, or two or more types. The metalloid element may be only one type, or two or more types.

[0078] The eluted element may be, for example, an element that dissolves in a dealloying solution in a dealloying method of an alloy. In terms of being able to further exhibit the effects of the present invention, the eluted element is preferably at least one element selected from the group consisting of Al, Zn, Ag, and Sn.

[0079] The metal elements other than the eluted elements typically include at least one selected from the group consisting of noble metal elements and base metal elements. The noble metal elements may be one type only, or two or more types. The base metal elements may be one type only, or two or more types.

[0080] Any appropriate noble metal element may be used as long as it does not impair the effects of the present invention, such as at least one selected from the group consisting of Ru, Rh, Pd, Os, Ir, Pt, and Au.

[0081] Any appropriate base metal element may be used as the base metal element as long as it does not impair the effects of the present invention. Examples of the base metal element include metal elements other than noble metal elements, and preferably at least one selected from the group consisting of Mg, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ce, Pr, Ta, W, and Bi.

[0082] As the metalloid element, any appropriate metalloid element can be used as long as it does not impair the effects of the present invention. Examples of the metalloid element include B, Si, Ge, As, Sb, and Te, and preferably at least one element selected from the group consisting of B, Si, Ge, and Sb.

[0083] The precursor layer is preferably formed by sputtering, for example, by co-sputtering using multiple targets (sometimes referred to as simultaneous sputtering) or sputtering using an alloy target.

[0084] Any appropriate sputtering conditions may be adopted as long as they do not impair the effects of the present invention. The atmosphere during sputtering may be, for example, a rare gas atmosphere such as argon. The pressure during sputtering may be, for example, 0.1 Pa to 10 Pa. Examples of the discharge method for sputtering include DC discharge, RF discharge, and MF-AC discharge. The sputtering temperature may be set to any appropriate temperature depending on the type of substrate, etc. The sputtering temperature may be, for example, -10°C to 150°C (e.g., sputtering onto a PET substrate), -10°C to 500°C (e.g., sputtering onto a PI substrate), or -10°C to 1000°C (e.g., sputtering onto a metal substrate).

[0085] In an embodiment in which the precursor layer is formed by co-sputtering, the precursor layer is formed, for example, by co-sputtering a first metal target with at least one selected from the group consisting of a second target and a second alloy target.

[0086] The first metal target may be, for example, an eluted element. The first metal target may be one type or two or more types.

[0087] The second target may be, for example, at least one selected from the group consisting of metal elements other than the eluted elements, metalloid elements, and carbon. The second target may be of only one type, or of two or more types.

[0088] The second alloy target may be, for example, an alloy composed of at least two elements selected from the group consisting of metal elements other than the eluted elements, metalloid elements, and carbon. The second alloy target may be of only one type, or of two or more types.

[0089] In an embodiment in which the precursor layer is formed by co-sputtering, the first metal target, the second target, and the second alloy target may be selected and the sputtering conditions may be appropriately set so that the content ratio of the eluted elements to at least one selected from the group consisting of metal elements other than the eluted elements, metalloid elements, and carbon in the resulting precursor layer, expressed as atomic weight percent (at %) of [eluted elements]:[total of metal elements other than the eluted elements, metalloid elements, and carbon], is preferably in the range of 50:50 to 99:1, more preferably 60:40 to 98:2, even more preferably 70:30 to 97:3, particularly preferably 75:25 to 96:4, and most preferably 80:20 to 95:5.

[0090] In an embodiment in which the precursor layer is formed by sputtering an alloy target, the alloy target is, for example, an alloy composed of a leaching element and at least one element selected from the group consisting of a metal element other than the leaching element, a metalloid element, and carbon. The alloy target may be of only one type, or of two or more types.

[0091] In an embodiment in which the precursor layer is formed by sputtering an alloy target, the alloy target may be appropriately selected and the sputtering conditions may be appropriately set so that the content ratio of the eluted element to at least one selected from the group consisting of metal elements other than the eluted element, metalloid elements, and carbon in the resulting precursor layer, expressed as atomic weight percent (at %) of [eluted element]:[at least one selected from the group consisting of metal elements other than the eluted element, metalloid elements, and carbon], is preferably in the range of 30:70 to 99.9 to 0.1, more preferably 50:50 to 99:1, even more preferably 60:40 to 98:2, even more preferably 70:30 to 97:3, particularly preferably 75:25 to 96:4, and most preferably 80:20 to 95:5.

[0092] When forming the precursor layer, film formation by sputtering may be performed multiple times for the purpose of adjusting the thickness (especially, adjusting to increase the thickness), etc. Furthermore, the number of targets may be increased for the purpose of adjusting the thickness (especially, adjusting to increase the thickness), etc.

[0093] [2-1-b. Dealloying Step] In the dealloying step, the precursor layer obtained in the precursor layer forming step is treated with a dealloying solution at a temperature of 40°C or higher. This dealloying step allows eluted elements contained in the precursor layer to be eluted into the dealloying solution, thereby forming a porous layer. Any appropriate conditions may be adopted as the conditions for the dealloying method as long as they do not impair the effects of the present invention.

[0094] The dealloying solution for treating the precursor layer may be, for example, any suitable acidic, alkaline, or neutral solution that can be used in a dealloying method. The concentration of the dealloying solution may be any suitable concentration depending on the purpose.

[0095] Examples of the acidic solution include an aqueous solution of hydrochloric acid, an aqueous solution of nitric acid, an aqueous solution of sulfuric acid, an aqueous solution of phosphoric acid, an aqueous solution of acetic acid, and a mixture thereof. Examples of the alkaline solution include an aqueous solution of sodium hydroxide and an aqueous solution of potassium hydroxide.

[0096] In the method for producing a laminated film according to an embodiment of the present invention, the treatment temperature in the dealloying method is 40°C or higher, and may be 50°C or higher, 60°C or higher, 70°C or higher, 80°C or higher, 90°C or higher, or 100°C or higher. The upper limit of the treatment temperature in the dealloying method is, for example, less than 300°C. By setting the treatment temperature in the dealloying method within the above range, the effects of the present invention can be more effectively exhibited.

[0097] In the method for producing a laminated film according to an embodiment of the present invention, the treatment with the dealloying solution in the dealloying method may be carried out under normal pressure or under pressure. As a method for carrying out the treatment under pressure, any appropriate pressurizing method may be adopted as long as it does not impair the effects of the present invention. Such a pressurizing method may, for example, be pressurizing in a pressure-resistant container such as an autoclave.

[0098] <2-2. Adhesion Layer Forming Step> The method for producing a laminated film according to an embodiment of the present invention may include an adhesion layer forming step before the porous layer forming step, and preferably includes an adhesion layer forming step of forming an adhesion layer on at least one surface of the substrate before the porous layer forming step. In this case, the method for producing a laminated film according to an embodiment of the present invention includes an adhesion layer forming step of forming an adhesion layer on at least one surface of the substrate, and the porous layer forming step is performed after the adhesion layer forming step. In this case, as one preferred embodiment of the present invention, a precursor layer is formed on the adhesion layer formed in the adhesion layer forming step by the precursor layer forming step described above.

[0099] The adhesion layer can be formed by any appropriate method as long as the effects of the present invention are not impaired. The adhesion layer is typically formed by a vacuum film formation method, for example, by vapor deposition or sputtering.

[0100] Examples of the formation by sputtering include single target sputtering, co-sputtering (sometimes referred to as simultaneous sputtering), and alloy target sputtering, with single target sputtering being typical.

[0101] Any appropriate sputtering conditions may be adopted as long as they do not impair the effects of the present invention. The atmosphere during sputtering may be, for example, a rare gas atmosphere such as argon. The pressure during sputtering may be, for example, 0.1 Pa to 10 Pa. Examples of the discharge method for sputtering include DC discharge, RF discharge, and MF-AC discharge. The sputtering temperature may be set to any appropriate temperature depending on the type of substrate, etc. The sputtering temperature may be, for example, -10°C to 150°C (e.g., sputtering onto a PET substrate), -10°C to 500°C (e.g., sputtering onto a PI substrate), or -10°C to 1000°C (e.g., sputtering onto a metal substrate).

[0102] In an embodiment in which the adhesion layer is formed by sputtering a single target, the single target is, for example, at least one selected from the group consisting of a metal element, a metalloid element, and carbon.

[0103] The metal element typically includes at least one selected from the group consisting of a noble metal element and a base metal element. The noble metal element may be only one type, or two or more types. The base metal element may be only one type, or two or more types.

[0104] Any appropriate noble metal element may be used as long as it does not impair the effects of the present invention, such as at least one selected from the group consisting of Ru, Rh, Pd, Os, Ir, Pt, and Au.

[0105] Any appropriate base metal element may be used as the base metal element as long as it does not impair the effects of the present invention. Examples of the base metal element include metal elements other than noble metal elements, and preferably at least one selected from the group consisting of Mg, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ce, Pr, Ta, W, and Bi.

[0106] As the metalloid element, any appropriate metalloid element can be used as long as it does not impair the effects of the present invention. Examples of the metalloid element include B, Si, Ge, As, Sb, and Te, and preferably at least one element selected from the group consisting of B, Si, Ge, and Sb.

[0107] One preferred embodiment of the adhesion layer contains at least one selected from the group consisting of base metal elements, semi-metal elements, and carbon.

[0108] In an embodiment in which the adhesion layer is formed by single-target sputtering, when a resin substrate (such as a polyethylene terephthalate (PET) substrate) is used as the substrate, it is a preferred embodiment in that the effects of the present invention can be more effectively exhibited by using at least one selected from the group consisting of base metal elements, metalloid elements, and carbon as the single target. On the other hand, in an embodiment in which the adhesion layer is formed by single-target sputtering, when carbon paper or carbon paper on which an MPL (Micro Porous Layer) is formed is used as the substrate, a noble metal element may be used as the single target. Therefore, it is a preferred embodiment in that the effects of the present invention can be more effectively exhibited by using at least one selected from the group consisting of metal elements (noble metal elements and base metal elements), metalloid elements, and carbon as the single target.

[0109] In an embodiment in which the adhesion layer is formed by co-sputtering, for example, it is formed by co-sputtering two of the above-mentioned single targets. When a resin substrate (such as a polyethylene terephthalate (PET) substrate) is used as the substrate, it is preferable to select at least one selected from the group consisting of base metal elements, metalloid elements, and carbon as at least one of the two single targets. When carbon paper or carbon paper with a microporous layer (MPL) formed thereon is used as the substrate, it is preferable to select at least one selected from the group consisting of metal elements (noble metal elements and base metal elements), metalloid elements, and carbon as at least one of the two single targets.

[0110] In an embodiment in which the adhesion layer is formed by sputtering an alloy target, the alloy target is an alloy composed of at least two elements selected from the group consisting of a metal element, a metalloid element, and carbon.

[0111] When a resin substrate (such as a polyethylene terephthalate (PET) substrate) is used as the substrate, it is preferable to select an alloy containing at least one selected from the group consisting of base metal elements, metalloid elements, and carbon as the alloy target. Furthermore, when carbon paper or carbon paper with a microporous layer (MPL) formed thereon is used as the substrate, an alloy containing at least one selected from the group consisting of metal elements (noble metal elements and base metal elements), metalloid elements, and carbon may be selected as the alloy target.

[0112] Before sputtering, the sputtering target (typically a substrate) may be cleaned by subjecting it to a plasma treatment, such as ion bombardment. Any appropriate conditions for the plasma treatment may be adopted as long as the effects of the present invention are not impaired.

[0113] 3. Uses of Laminate Films Because laminate films according to embodiments of the present invention can suppress deterioration or alteration of the porous layer, they can be used in a variety of applications, including optical applications (e.g., refractive index control members), catalyst applications (e.g., catalyst composites for water electrolysis (laminate composites including a porous layer as a catalyst layer and an electrolyte membrane), catalyst composites for fuel cells (laminate composites including a porous layer as a catalyst layer and an electrolyte membrane), catalyst composites for CO electrolysis (e.g., for the electrolytic synthesis of formic acid or synthetic fuels) (laminate composites including a porous layer as a catalyst layer and an electrolyte membrane)), thermocompression bonding (thermal lamination), and membrane applications (e.g., water evaporation promotion membranes). In particular, because the porous layer can function as a catalyst layer, laminate films according to embodiments of the present invention are suitable for use in catalyst composites for water electrolysis and catalyst composites for fuel cells.

[0114] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The test and evaluation methods used in the examples are as follows.

[0115] <Thickness of Layer Formed by Sputtering> The thickness of the layer formed by sputtering each element onto the glass substrate was calculated using a stylus film thickness step meter (Dektak, manufactured by Bruker). Based on the obtained layer thickness of each element and the elemental composition of the layer actually formed by sputtering, the thickness of the layer formed by sputtering was calculated, and this calculated thickness was defined as the thickness of the layer formed by sputtering.

[0116] <Evaluation of the Presence or Absence of Peeling of Porous Layer from Substrate (Durability Evaluation)> The obtained laminated film was visually inspected to see whether or not the porous layer had peeled from the substrate, and evaluated according to the following criteria: ◯: No peeling was observed. Δ: Spot-like peeling was observed in some areas. ×: Peeling was observed throughout the film.

[0117] <Surface Observation of Porous Layer (Evaluation of Presence or Absence of Porous Structure)> The surface of the porous layer was observed using an FE-SEM (manufactured by Hitachi High-Tech Corporation, product name "SU8220"). During surface observation, the presence or absence of a porous structure was confirmed at an acceleration voltage of 2 kV, a WD of 4 mm, and a magnification of 100,000x, while the observation surface was in contact with the substrate holder using conductive tape to prevent surface charge-up. Furthermore, when the pore diameter was small and it was difficult to determine the presence or absence of a porous structure by surface observation, a FE-TEM (manufactured by JEOL Ltd., JEM-2800) was used to observe the cross section of the porous layer. The cross section was prepared using an FIB microsampling method (manufactured by Hitachi High-Tech Corporation, FB2200), and FE-TEM analysis was performed. The presence or absence of a porous structure was confirmed using the FE-TEM at an acceleration voltage of 200 kV and a magnification of 1,000,000x. Evaluation was based on the following criteria: ∘: Pores were recognizable based on the difference in brightness. ×: No difference in brightness was observed and the holes were not recognizable.

[0118] <Observation and evaluation of deterioration and alteration of porous layer> The sample after dealloying treatment was placed in an oven at 80°C for 24 hours to cause accelerated deterioration. Thereafter, the optical color before and after placing in the oven was evaluated using a spectrophotometer CM-2600d manufactured by KONICA MINOLTA, and the deterioration and alteration of the porous layer was evaluated using the b* value in reflection. The evaluation criteria were as follows: ◯: No change in b* in reflection was observed △: A slight change in b* in reflection was observed ×: A large change in b* in reflection was observed

[0119] <Measurement of remaining amount of eluted elements in porous layer> The obtained porous layer was subjected to qualitative analysis using a scanning X-ray fluorescence analyzer (manufactured by Rigaku Corporation, product name "ZSX Primus III+"), and the amount of eluted elements remaining in the porous layer was measured by a 1 cm 2 The mass (mg) per 1000 sq. m of the eluted element and at least one element selected from the group consisting of metal elements, metalloid elements, and carbon other than the eluted element was analyzed to calculate the atomic weight percentage (at %), and the amount of the eluted element remaining in the porous layer was measured. 2 ) was considered ND.

[0120] <Abbreviations for substrates in Examples and Comparative Examples> PET: polyethylene terephthalate substrate, manufactured by Toyobo Co., Ltd., trade name "A4160", thickness = 188 μm PI: polyimide substrate, manufactured by Xenomax Japan Co., Ltd., trade name "XENOMAX", thickness = 38 μm Ni porous body: thickness = 0.3 mm (300 μm) Zirfon: manufactured by AGFA, trade name "Zirfon (registered trademark)", thickness = 500 μm Cu foil: manufactured by Fukuda Metal Foil & Powder Co., Ltd., thickness = 18 μm Ti foil: manufactured by Nilaco Corporation, thickness = 50 μm

[0121] <Abbreviations of sputtering targets for adhesion layers in Examples and Comparative Examples> Cr: Cr target Ni: Ni target Cu: Cu target Au: Au target Ti: Ti target

[0122] <Abbreviations for sputtering targets of precursor layer in Examples and Comparative Examples> Ni6-Al94 (at %): Ni-Al alloy target, Ni:Al=6:94 (atomic weight % ratio) Ni10-Al90 (at %): Ni-Al alloy target, Ni:Al=10:90 (atomic weight % ratio) Ni12-Al88 (at %): Ni-Al alloy target, Ni:Al=12:88 (atomic weight % ratio) Ni18-Al82 (at %): Ni-Al alloy target, Ni:Al=18:82 (atomic weight % ratio) Ni24-Al76 (at %): Ni-Al alloy target, Ni:Al=24:76 (atomic weight % ratio) Cu10 (at %) + Al90 (at %): Co-sputtering of Cu target and Al target (Cu:Al=10:90 (atomic weight % ratio)) Au15 (at%) + Al85 (at%): Co-sputtering of Au target and Al target (Au:Al = 15:85 (atomic weight %)) Ni-Fe10 (at%) + Al90 (at%): Co-sputtering of Ni-Fe alloy target (Ni:Fe = 50:50, atomic weight %) and Al target (Ni-Fe:Al = 10:90 (atomic weight %)) Pt10 (at%) + Al90 (at%): Co-sputtering of Pt target and Al target (Pt:Al = 10:90 (atomic weight %)) Ir20 (at%) + Al80 (at%): Co-sputtering of Ir target and Al target (Ir:Al = 20:80 (atomic weight %)) Pt 20 (at%) + Zn 80 (at%): Co-sputtering of a Pt target and a Zn target (Pt:Zn = 20:80 (atomic weight %))

[0123] <Abbreviations for dealloying solutions in Examples and Comparative Examples> NaOHaq: 0.5M NaOH aqueous solution HNO3aq: 1 wt% HNO3 aqueous solution

[0124] [Example 1] A polyimide substrate was prepared as a substrate. A multi-target simultaneous sputtering apparatus (2-inch specification) was used. First, the substrate was introduced into the apparatus, and the pressure was increased to 5.0 × 10 -4After confirming that the pressure was below 1 Pa, the substrate was cleaned by reverse sputtering. Reverse sputtering was performed at room temperature (23 ° C.) in an Ar gas atmosphere at 0.4 Pa, 30 W, and 60 seconds. Next, a Cr target was used as the sputtering target, and a film was formed at room temperature (23 ° C.) under an Ar gas atmosphere at a pressure of 0.3 Pa to a thickness of 50 nm, forming an adhesion layer. Next, a Ni-Al alloy target (Ni:Al = 6:94 (atomic weight %)) was used as the sputtering target, and a film was formed at room temperature (23 ° C.) under an Ar gas atmosphere at a pressure of 0.3 Pa to a thickness of 749 nm, forming a precursor layer. The obtained laminate was immersed in a 0.5 M NaOH aqueous solution as a dealloying solution and left to stand at 80 ° C. for 10 minutes to perform a dealloying treatment, and the eluted element Al was dissolved into the dealloying solution. After the dealloying treatment, the sample was immersed in ion-exchanged water and left to stand for 3 minutes, which was repeated twice for cleaning, and then thoroughly dried naturally in the air. The results are shown in Table 1.

[0125] Example 2 The procedure was the same as in Example 1, except that the precursor layer was formed using a Ni-Al alloy target (Ni:Al=10:90 (atomic weight ratio)) as the sputtering target, in an Ar gas atmosphere at a pressure of 0.3 Pa and at room temperature (23° C.) so that the film thickness would be 500 nm, as shown in Table 1. The results are shown in Table 1.

[0126] Example 3 The same procedure as in Example 2 was carried out, except that the temperature of the dealloying treatment was changed to 50° C. as shown in Table 1. The results are shown in Table 1.

[0127] Example 4 The same procedure as in Example 2 was carried out, except that Zirfon was used as the substrate, and the adhesion layer was formed using a Ni target as the sputtering target under an Ar gas atmosphere at a pressure of 0.3 Pa at room temperature (23° C.) so that the film thickness would be 50 nm, as shown in Table 1. The results are shown in Table 1.

[0128] Example 5 The same procedures as in Example 1 were carried out, except that a Ni porous body was used as the substrate, no adhesion layer was provided, and the precursor layer was formed using a Ni-Al alloy target (Ni:Al=12:88 (atomic weight %)) as the sputtering target, under an Ar gas atmosphere at a pressure of 0.3 Pa and at room temperature (23° C.) so that the film thickness would be 390 nm, as shown in Table 1. The results are shown in Table 1.

[0129] Example 6 The same procedure as in Example 2 was carried out, except that Zirfon was used as the substrate, and the adhesion layer was formed using a Cr target as the sputtering target in an Ar gas atmosphere at a pressure of 0.3 Pa at room temperature (23° C.) so that the film thickness would be 100 nm, as shown in Table 1. The results are shown in Table 1.

[0130] Example 7 The same procedure as in Example 2 was carried out, except that the adhesion layer was formed to a thickness of 5 nm as shown in Table 1. The results are shown in Table 1.

[0131] Example 8 The same procedure as in Example 2 was carried out, except that the adhesion layer was formed to a thickness of 3 nm as shown in Table 1. The results are shown in Table 1.

[0132] Example 9 As shown in Table 1, a precursor layer was formed by co-sputtering at room temperature (23°C) using an Au target and an Al target as sputtering targets under an Ar gas atmosphere at a pressure of 0.3 Pa, with an Au:Al ratio of 15:85 (atomic weight percentage) and a film thickness of 200 nm, except that the dealloying solution was changed to a 1 wt% HNO3 aqueous solution, as in Example 1. The results are shown in Table 1.

[0133] Example 10 The same procedure as in Example 9 was carried out, except that the temperature of the dealloying treatment was changed to 50° C. as shown in Table 1. The results are shown in Table 1.

[0134] Example 11 The same procedure as in Example 9 was carried out, except that a polyethylene terephthalate substrate was used as the substrate, as shown in Table 1. The results are shown in Table 1.

[0135] Example 12 The procedure was the same as in Example 1, except that, as shown in Table 1, a Cu foil was used as the substrate, the adhesion layer was formed by sputtering a Cu target under an Ar gas atmosphere at a pressure of 0.3 Pa to a thickness of 5 nm at room temperature (23°C), and the precursor layer was formed by co-sputtering a Cu target and an Al target under an Ar gas atmosphere at a pressure of 0.3 Pa with a Cu:Al ratio of 10:90 (atomic weight ratio) to a thickness of 450 nm at room temperature (23°C). The results are shown in Table 1.

[0136] Example 13 As shown in Table 1, the adhesion layer was formed by sputtering a Cr target under an Ar gas atmosphere at a pressure of 0.3 Pa to a thickness of 5 nm at room temperature (23°C), and the precursor layer was formed by co-sputtering a Ni:Fe alloy target (Ni:Fe = 50:50) (atomic weight ratio) and an Al target under an Ar gas atmosphere at a pressure of 0.3 Pa to a thickness of 100 nm at room temperature (23°C). The same procedures as in Example 1 were carried out, except that the adhesion layer was formed by sputtering a Ni:Fe alloy target (Ni:Fe = 50:50) (atomic weight ratio) and an Al target under an Ar gas atmosphere at a pressure of 0.3 Pa to a thickness of 100 nm at room temperature (23°C). The results are shown in Table 1.

[0137] Example 14 The same procedures as in Example 1 were carried out except that, as shown in Table 1, the adhesion layer was formed by sputtering a Cr target under an Ar gas atmosphere at a pressure of 0.3 Pa to a thickness of 5 nm at room temperature (23° C.), and the precursor layer was formed by co-sputtering a Pt target and an Al target under an Ar gas atmosphere at a pressure of 0.3 Pa with a Pt:Al ratio of 10:90 (atomic weight ratio) to a thickness of 100 nm at room temperature (23° C.). The results are shown in Table 1.

[0138] Example 15 The procedure was the same as in Example 1, except that the precursor layer was formed using a Ni-Al alloy target (Ni:Al=24:76 (atomic weight ratio)) as the sputtering target, in an Ar gas atmosphere at a pressure of 0.3 Pa and at room temperature (23° C.) so that the film thickness would be 200 nm, as shown in Table 1. The results are shown in Table 1.

[0139] Example 16 As shown in Table 1, the substrate was a Ti foil, and the adhesion layer was formed by sputtering a Ti target under an Ar gas atmosphere at a pressure of 0.3 Pa to a thickness of 50 nm at room temperature (23°C). The precursor layer was formed by co-sputtering an Ir target and an Al target under an Ar gas atmosphere at a pressure of 0.3 Pa with an Ir:Al ratio of 20:80 (atomic weight ratio) to a thickness of 200 nm at room temperature (23°C). The procedure was the same as in Example 1, except that the dealloying temperature was changed to 100°C and the dealloying was performed under pressure (1 MPa to 3 MPa). The results are shown in Table 1.

[0140] Example 17 As shown in Table 1, the adhesion layer was formed by sputtering a Cr target under an Ar gas atmosphere at a pressure of 0.3 Pa at room temperature (23°C) to a thickness of 5 nm, and the precursor layer was formed by co-sputtering a Pt target and a Zn target under an Ar gas atmosphere at a pressure of 0.3 Pa with a Pt:Zn ratio of 20:80 (atomic weight ratio) to a thickness of 250 nm at room temperature (23°C). The procedure was the same as in Example 1, except that the dealloying temperature was changed to 100°C and the dealloying was performed under pressure (1 MPa to 3 MPa). The results are shown in Table 1.

[0141] [Comparative Example 1] As shown in Table 1, the adhesion layer was formed by sputtering a Cr target under an Ar gas atmosphere at a pressure of 0.3 Pa at room temperature (23°C) to a thickness of 5 nm, and the precursor layer was formed by co-sputtering a Pt target and an Al target under an Ar gas atmosphere at a pressure of 0.3 Pa with a Pt:Al ratio of 10:90 (atomic weight ratio) to a thickness of 100 nm at room temperature (23°C). The same procedures were carried out as in Example 1, except that the temperature for the dealloying treatment was changed to room temperature (23°C). The results are shown in Table 1.

[0142] Comparative Example 2 As shown in Table 1, the adhesion layer was formed by sputtering an Au target under an Ar gas atmosphere at a pressure of 0.3 Pa at room temperature (23° C.) to a thickness of 50 nm, and the precursor layer was formed by co-sputtering an Au target and an Al target under an Ar gas atmosphere at a pressure of 0.3 Pa with an Au:Al ratio of 15:85 (atomic weight percentage) to a thickness of 200 nm at room temperature (23° C.). The procedures were the same as in Example 1, except that the dealloying solution was changed to a 1 wt % HNO aqueous solution and the dealloying treatment temperature was changed to room temperature (23° C.). The results are shown in Table 1.

[0143] Comparative Example 3 The same procedure as in Example 16 was carried out, except that the dealloying treatment temperature was changed to 23° C. and was not carried out under pressure. The results are shown in Table 1.

[0144]

[0145] The laminated film according to the embodiment of the present invention can be used in a variety of applications, including optical applications (e.g., refractive index control members), catalyst applications (e.g., catalyst composites for water electrolysis (laminated composites including a porous layer as a catalyst layer and an electrolyte membrane), catalyst composites for fuel cells (laminated composites including a porous layer as a catalyst layer and an electrolyte membrane), catalyst composites for CO electrolysis (e.g., for electrolytic synthesis of formic acid or synthetic fuels) (laminated composites including a porous layer as a catalyst layer and an electrolyte membrane)), thermocompression bonding (thermal lamination) applications, and membrane applications (e.g., water evaporation promotion membranes).

Claims

1. A laminated film including a porous layer, wherein the total content of eluted elements in the porous layer is 20 atomic weight % or less.

2. The laminated film according to claim 1, wherein the eluted element comprises at least one element selected from the group consisting of Al, Zn, Ag, and Sn.

3. The laminated film according to claim 1, wherein the porous layer contains at least one element selected from the group consisting of metal elements other than elutable elements, metalloid elements, and carbon.

4. The laminate film according to claim 3, wherein the metal elements other than the eluted elements include at least one selected from the group consisting of Mg, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ce, Pr, Ta, W, Os, Ir, Pt, Au, and Bi.

5. The laminated film according to claim 3, wherein the metalloid element comprises at least one element selected from the group consisting of B, Si, Ge, and Sb.

6. The laminated film of claim 1, comprising a substrate.

7. The laminated film according to claim 6, wherein the substrate and the porous layer are laminated via an adhesive layer.

8. The laminated film according to claim 7, wherein the adhesive layer has a thickness of 1 nm to 100 nm.

9. The laminated film according to claim 7, wherein the adhesive layer contains at least one element selected from the group consisting of base metal elements, semi-metal elements, and carbon.

10. The laminate film according to claim 9, wherein the base metal element comprises at least one selected from the group consisting of Mg, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ce, Pr, Ta, W, and Bi.

11. The laminated film according to claim 6, wherein the porous layer is provided on both sides of the substrate.

12. The laminated film according to claim 6, wherein the surface of the substrate on the porous layer side contains a resin.

13. A method for producing a laminated film including a porous layer, comprising: a porous layer-forming step of forming the porous layer, the porous layer-forming step comprising: a precursor layer-forming step of forming a precursor layer containing an alloy of a leachable element and at least one element selected from the group consisting of a metal element other than the leachable element, a metalloid element, and carbon; and a dealloying step of treating the precursor layer with a dealloying solution at a temperature of 40°C or higher.

14. The method for producing a laminated film according to claim 13, wherein the eluted element includes at least one element selected from the group consisting of Al, Zn, Ag, and Sn.

15. The method for producing a laminated film according to claim 13, wherein the precursor layer is formed by co-sputtering a first metal target with at least one selected from the group consisting of a second target and a second alloy target, the first metal target being the eluted element, the second target being at least one selected from the group consisting of a metal element other than the eluted element, a metalloid element, and carbon, and the second alloy target being an alloy composed of at least two selected from the group consisting of a metal element other than the eluted element, a metalloid element, and carbon.

16. The method for producing a laminated film according to claim 13, wherein the precursor layer is formed by sputtering an alloy target, and the alloy target is an alloy composed of the eluted element and at least one element selected from the group consisting of a metal element other than the eluted element, a metalloid element, and carbon.

17. The method for producing a laminated film according to claim 13, wherein in the porous layer forming step, the porous layer is formed on at least one side of the substrate.

18. The method for producing a laminated film according to claim 17, further comprising a step of forming an adhesive layer on at least one surface of the substrate, the step of forming the porous layer being carried out after the step of forming the adhesive layer.

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