CN111727277A

CN111727277A - Aluminum laminate and method for producing same

Info

Publication number: CN111727277A
Application number: CN201980013622.9A
Authority: CN
Inventors: 新宫享; 大八木光成
Original assignee: Toyo Aluminum KK
Current assignee: Toyo Aluminum KK
Priority date: 2018-02-26
Filing date: 2019-01-31
Publication date: 2020-09-29
Also published as: TW201937008A; WO2019163466A1; JP2019147974A; KR20200127156A

Abstract

The aluminum laminate (10) is provided with: an aluminum substrate (1) having a first face (1A); and an anodic oxide film (2) which is formed in contact with the first surface (1A) and has a second surface (2A) located at a position distant from the first surface (1A) in the direction intersecting the first surface (1A). A surface layer of the aluminum substrate (1) including the first surface (1A) contains aluminum having a purity of 99.9 mass% or more and iron having a purity of 0.001 mass% or more and 0.02 mass% or less. The surface roughness Ra of the second surface (2A) of the anodic oxide film (2) is 15nm or less. The thickness of the anodic oxide film (2) in the direction intersecting the direction is 2 [ mu ] m or more and 20 [ mu ] m or less. The value T1 (unit: mum) of the overall thickness of the aluminum laminate (1) in the direction intersecting the aluminum laminate and the value T2 (unit: mum) of the thickness of the anodic oxide film (2) in the direction intersecting the aluminum laminate satisfy the relationship T1+10 XT 2 ≦ 230. The hole sealing degree admittance Y value of the first anodic oxide coating (2) is less than 100 mu S.

Description

Aluminum laminate and method for producing same

Technical Field

The present invention relates to an aluminum laminate and a method for producing the same.

Background

In recent years, with rapid progress in displays such as liquid crystal, organic EL, and electronic paper, thin-film solar cells, touch panels, and the like, electronic devices are required to be thin, light, and flexible. In addition, in the electronic devices for the above-mentioned applications, from the viewpoint of preventing occurrence of abnormality such as pixel failure of a display, high barrier property is required to suppress quality degradation due to gas such as water vapor or oxygen from the outside, as in the case of general electronic devices.

Therefore, studies have been made on the thinning, weight reduction, and flexibility of a substrate constituting an electronic device while achieving high barrier properties. As a method for achieving reduction in thickness, weight, and flexibility of a substrate, studies are being made on using a resin as a material constituting the substrate. However, a substrate made of a resin such as a plastic film is relatively permeable to gas such as water vapor and oxygen from the outside. In this case, in order to achieve high barrier properties, it is necessary to form a thin film having barrier properties on a substrate made of a resin. Therefore, the substrate itself of the electronic device is preferably made of a material having low gas permeability and has barrier properties.

In addition, since the electronic device for the above-mentioned application uses visible light in many cases, a substrate exhibiting high reflectance with respect to visible light is suitable for a substrate constituting the electronic device.

In addition, as a method for manufacturing such an electronic device, a roll-to-roll method is desired from the viewpoint of cost reduction.

As described above, aluminum (a1) is a constituent material of a substrate which has high barrier properties and high reflectance, can be made thin, lightweight, and flexible, and can be manufactured by roll-to-roll processing.

Aluminum has high barrier properties and high reflectance to visible light compared to plastic films. Further, by making aluminum foil, it is possible to make the aluminum thin, light, and flexible. In addition, the aluminum foil can be subjected to roll-to-roll processing.

On the other hand, an insulating layer for ensuring electrical insulation between the substrate and the electrodes stacked on the substrate is generally disposed on the substrate of the electronic device for the above-described application. The insulation breakdown voltage of such an insulating layer is generally 0.2kV or more. An anodic oxide film having insulating properties can be easily formed on the surface of aluminum by anodic oxidation treatment.

Therefore, a laminate of aluminum and an anodic oxide film laminated on the aluminum is suitable for the substrate of the electronic device for the above-mentioned application.

Jp 2015-199985 a (patent document 1) proposes a method for producing an anodized-film aluminum substrate, which is characterized in that the ratio of Fe: 0.05 to 0.40 mass%, Si: 0.02 to 0.20 mass%, the balance being aluminum and unavoidable impurities, and cold rolling the aluminum alloy to produce 1000 intermetallic compounds having a maximum height roughness Rz of 0.50 [ mu ] m or less on the roughness curve of the surface and an equivalent circle diameter of 1 [ mu ] m or more on the surface per mm²Further, the above-mentioned rolled aluminum material is subjected to an anodic oxidation treatment in a sulfuric acid aqueous solution having a liquid temperature of 15 ℃ or lower.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2015-199985

Disclosure of Invention

Problems to be solved by the invention

Patent document 1 discloses a laminate of an aluminum substrate and an anodic oxide film formed on the surface of the aluminum substrate to have a thickness of 0.1 to 20 μm. However, the results of the studies by the present inventors confirmed that: the aluminum laminate described as an example in patent document 1, in which an anodic oxide film is laminated on an aluminum plate having a thickness of 0.3mm, does not have sufficient flexibility. Specifically, cracks were observed in the anodized film layer of the aluminum laminate produced by roll-to-roll processing using a guide roll having a minimum diameter of 50 mm.

Accordingly, an object of the present invention is to provide an aluminum laminate which has an anodic oxide film having an insulation breakdown voltage of 0.2kV or more and in which cracks are not generated in the anodic oxide film layer even in a roll-to-roll process using a guide roll having a minimum diameter of 50 mm.

Means for solving the problems

As a result of intensive studies to solve the above problems, the present inventors have found that when the composition of the aluminum base material, the surface smoothness and thickness of the anodic oxide film, and the aluminum laminate satisfy specific conditions, an aluminum laminate in which the insulation breakdown voltage of the anodic oxide film is 0.2kV or more and cracks in the anodic oxide film layer are not generated even when the aluminum laminate passes through a guide roll having a minimum diameter of 50mm can be obtained. The bending process with a minimum diameter of 50mm or less is performed in a bending process test (hereinafter simply referred to as a bending process test) in which the surface of the anodic oxide film is visually observed after the aluminum laminate is subjected to a process of holding for 10 seconds at least along the outer peripheral surface of a cylinder with a diameter of 50mm, and no crack is observed in the surface of the anodic oxide film.

That is, the aluminum laminate according to one embodiment of the present invention has the following features. An aluminum laminate according to one embodiment includes: an aluminum substrate having a first face; and a first anodic oxide film that is formed in contact with the first surface and has a second surface located away from the first surface in a direction intersecting the first surface. A surface layer of the aluminum base material including the first surface contains aluminum having a purity of 99.9 mass% or more and iron having a purity of 0.001 mass% or more and 0.02 mass% or less. The surface roughness Ra of the second surface of the first anodic oxide coating is 15nm or less. The first anodic oxide film has a thickness of 3 μm or more and 20 μm or less in the direction intersecting the first anodic oxide film. The value T1 (unit: mum) of the overall thickness of the aluminum laminate in the direction intersecting the aluminum laminate and the value T2 (unit: mum) of the thickness of the first anodic oxide film in the direction intersecting the aluminum laminate satisfy the relationship X +10 XY ≦ 230.

In the aluminum laminate according to the above-described embodiment, the pore sealing admittance Y value of the anodic oxide film is preferably less than 100 μ S.

The aluminum laminate according to another embodiment of the present invention has the following features. An aluminum laminate according to another embodiment includes: an aluminum substrate having a first face; and a first anodic oxide film that is formed in contact with the first surface and has a second surface located away from the first surface in a direction intersecting the first surface. A surface layer of the aluminum base material including the first surface contains aluminum having a purity of 99.9 mass% or more and iron having a purity of 0.001 mass% or more and 0.02 mass% or less. The surface roughness Ra of the second surface of the first anodic oxide coating is 15nm or less. The first anodic oxide film has a thickness of 2 μm or more and 20 μm or less in the direction intersecting the first anodic oxide film. The value T1 (unit: mum) of the overall thickness of the aluminum laminate in the direction intersecting the aluminum laminate and the value T2 (unit: mum) of the thickness of the first anodic oxide film in the direction intersecting the aluminum laminate satisfy the relationship X +10 XY ≦ 230. The porosity admittance Y value of the anodic oxide film is less than 100 [ mu ] S.

The present inventors have confirmed that the insulation breakdown voltage of the anodic oxide film of the aluminum laminate according to the above two embodiments is 0.2kV or more. The present inventors have confirmed that the aluminum laminate according to the above two embodiments has high reflection properties against visible light.

In the aluminum laminate, the anodic oxide film is preferably a sulfuric acid anodic oxide film.

The method for producing the aluminum laminate includes the steps of: preparing an aluminum base material having a surface roughness Ra of 15nm or less on a first surface; and forming a first anodic oxide film having a thickness of 2 to 20 [ mu ] m in the cross direction on the first surface of the aluminum substrate using an electrolytic solution containing sulfuric acid.

Effects of the invention

According to the present invention, it is possible to provide an aluminum laminate which has an anodic oxide film having an insulation breakdown voltage of 0.2kV or more and in which cracks are not generated in the anodic oxide film layer even in a roll-to-roll process using a guide roll having a minimum diameter of 50 mm.

Drawings

Fig. 1 is a schematic cross-sectional view showing an aluminum laminate according to the present embodiment.

Fig. 2 is a flowchart illustrating the method for manufacturing an aluminum laminate according to the present embodiment.

Fig. 3 is a schematic cross-sectional view showing a modification of the aluminum laminate according to the present embodiment.

Fig. 4 is a flowchart showing a modification of the method for producing an aluminum laminate according to the present embodiment.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding portions are denoted by the same reference numerals, and description thereof will not be repeated.

[ constitution of aluminum laminate ]

As shown in fig. 1, the aluminum laminate 10 according to the present embodiment includes an aluminum substrate 1 and a first anodic oxide film 2.

The aluminum substrate 1 has a first surface 1A and a third surface 1B located on the opposite side of the first surface 1A. The material constituting the aluminum substrate 1 contains aluminum (Al). The aluminum substrate 1 is, for example, an aluminum foil.

The aluminum purity of the surface layer including the first surface 1A of the aluminum substrate 1 is 99.9 mass% or more.

The surface layer of the aluminum substrate 1 including the first surface 1A contains 0.001 mass% to 0.02 mass% of iron (Fe). If the iron content is less than 0.001 mass%, the strength of the aluminum substrate 1 is reduced. On the other hand, since iron has a low solid solubility in aluminum, FeAl is easily crystallized during casting of aluminum₃And the like. These crystals have a lower reflectance in the visible light region than that of the aluminum substrate, and cause a reduction in the glossiness and visible light reflectance of the aluminum substrate. Further, if an intermetallic compound such as FeAl3 is present, the anodic oxide film becomes uneven, the transparency of the anodic oxide film is significantly deteriorated, and the reflectance is lowered, and not only is the hardness of the anodic oxide film lowered, but also the dielectric breakdown voltage of the anodic oxide film is lowered. Therefore, the iron content must be in0.02 mass% or less.

The surface layer of the aluminum substrate 1 including the first surface 1A may contain, for example, 0.001 mass% to 0.09 mass% of silicon (Si). Since silicon has a high solid solubility in aluminum and is difficult to form crystals, the reflectance in the visible light region is not reduced if the silicon is contained in such an amount that no crystals are formed. In addition, the mechanical strength of the aluminum substrate 1 in which 0.001 mass% or more of silicon is dissolved is improved by solid solution strengthening as compared with the mechanical strength of the aluminum substrate 1 in which silicon is not dissolved. Therefore, for example, the aluminum substrate 1 with 0.001 mass% or more of silicon dissolved therein can be easily rolled into a foil with a smaller thickness while maintaining the same mechanical strength as the aluminum substrate 1 with silicon not dissolved therein. On the other hand, when the aluminum substrate 1 contains more than 0.09 mass% of silicon, if the thickness of the first anodic oxide film 2 is increased, the transparency of the first anodic oxide film 2 is decreased, and the reflectance is decreased. Further, the hardness of the second surface 2A of the first anodic oxide film 2 also decreases. Therefore, the content of silicon must be 0.09 mass% or less.

The surface layer of the aluminum substrate 1 including the first surface 1A includes impurities, the balance being Al, Fe, and Si. The impurities are, for example, inevitable impurities, and may include a trace amount of impurities which do not largely affect the glossiness and the total reflectance of visible light, in addition to the inevitable impurities. The impurities include, for example, at least 1 element selected from copper (Cu), manganese (Mn), magnesium (Mg), zinc (Zn), titanium (Ti), vanadium (V), nickel (Ni), chromium (Cr), zirconium (Zr), boron (B), gallium (Ga), bismuth (Bi), and the like. The content of each impurity element is 0.01 mass% or less.

The surface layer including the first surface 1A of the aluminum substrate 1 is a region extending from the first surface 1A to a distance of 5 μm from the first surface 1A in a direction (depth direction) intersecting the first surface 1A. The surface roughness Ra of the first surface 1A is preferably 15nm or less. As a method for forming the first surface 1A of the aluminum substrate 1 with such a small surface roughness Ra, there are polishing processes such as physical polishing, electrolytic polishing, and chemical polishing, and cold rolling using a roll having a mirror surface.

The composition of the other part of the aluminum substrate 1 than the surface layer is not particularly limited, and the aluminum substrate 1 may be formed as a clad material, for example.

The first anodic oxide film 2 is formed in contact with the first surface 1A. The first anodic oxide film 2 has a surface in contact with the first surface 1A, and a second surface 2A located away from the first surface 1A in a direction intersecting with the first surface 1A. The first anodic oxide film 2 is formed by anodizing the first surface 1A of the aluminum substrate 1. The anodizing treatment may be a known anodizing treatment method, and for example, may be an anodizing treatment using an electrolytic solution containing at least one of sulfuric acid, boric acid, oxalic acid, and phosphoric acid. Preferably, the first anodic oxide film 2 is formed by an anodic oxidation treatment using an electrolytic solution containing sulfuric acid. That is, the first anodic oxide film 2 is preferably a sulfuric acid anodic oxide film. The first anodic oxide film 2 is subjected to sealing treatment. The first anodic oxide film 2 is preferably transparent.

The thickness of the first anodic oxide film 2 in the direction intersecting the aforementioned direction is 2 μm or more and 20 μm or less. The thickness of the first anodic oxide film 2 in the direction intersecting the above direction is the distance between the surface of the first anodic oxide film 2 in contact with the first surface 1A and the second surface 2A.

When the thickness of the first anodic oxide film 2 in the direction intersecting the above direction is less than 2 μm, it is difficult to set the insulation breakdown voltage of the anodic oxide film to 0.2kV or more. On the other hand, when the thickness of the first anodic oxide film 2 in the intersecting direction is larger than 20 μm, cracks are likely to occur on the surface of the first anodic oxide film 2 in the bending test.

The present inventors confirmed that, as shown in examples described later, the first anodic oxide film 2 having a thickness in the intersecting direction of 3 μm to 20 μm has high insulation properties regardless of the sealing degree, and that the occurrence of cracks is suppressed in the bending test.

The present inventors have confirmed that the dielectric breakdown voltage of the first anodic oxide film 2 varies depending on the value of the pore opening tolerance Y of the first anodic oxide film 2, and particularly, when the thickness of the first anodic oxide film 2 in the intersecting direction is 2 μm or more and 3 μm or less, the value of the pore opening tolerance Y should be set to be less than a certain value so that the dielectric breakdown voltage is 0.2kV or more.

Specifically, the first anodic oxide film 2 having a thickness in the intersecting direction of 2 μm to 3 μm and a pore sealing tolerance Y value of less than 100 μ S has an insulation breakdown voltage of 0.2kV or more. On the other hand, the first anodic oxide film 2 having a thickness in the intersecting direction of 2 μm to 3 μm and a pore sealing tolerance Y value of 100 μ S or more has an insulation breakdown voltage of less than 0.2 kV.

The surface roughness Ra of the second surface 2A of the first anodic oxide film 2 is 20nm or less. A part of the light incident on the aluminum laminate 10 is reflected by the second surface 2A of the first anodic oxide film 2, and the rest is refracted by the second surface 2A and reaches the first surface 1A of the aluminum substrate 1. When the surface roughness Ra of the second surface 2A of the first anodic oxide film 2 exceeds 15nm, the light reflected by the second surface 2A or the light refracted by the second surface 2A diffuses, and thus the glossiness and total reflectance of the second surface 2A decrease. When the surface roughness Ra of the second surface 2A of the first anodic oxide film 2 is 15nm or less, the diffusion of light reflected on the second surface 2A or light refracted on the second surface 2A can be suppressed, and the second surface 2A has high glossiness and high total reflectance. The surface roughness Ra of the second surface 2A of the first anodic oxide film 2 is calculated by extending the arithmetic average roughness Ra defined by JIS B0601(2001 edition) and ISO4287(1997 edition) into three dimensions so as to be applicable to the surface.

In order to set the surface roughness Ra of the second surface 2A of the first anodic oxide film 2 to the above numerical range, the surface roughness Ra of the first surface 1A of the aluminum substrate 1 is preferably reduced. Preferably, the surface roughness Ra of the first surface 1A of the aluminum substrate 1 is 15nm or less, as described above.

The value T1 (unit: μm, see fig. 1) of the total thickness of the aluminum laminate 10 in the intersecting direction and the value T2 (unit: μm, see fig. 1) of the thickness of the first anodic oxide film 2 in the intersecting direction satisfy the relational expression X +10 × Y ≦ 230. The present inventors have confirmed that when the aluminum laminate satisfying the above relational expression and having X +10 × Y exceeding 230 is subjected to the bending test described above with the minimum diameter being 50mm or less, cracks are generated in the anodic oxide film. On the other hand, the present inventors have found that the aluminum laminate having the above characteristics and satisfying the above relational expression suppresses the occurrence of cracks when the bending test is performed.

Specifically, the present inventors have conducted intensive studies on an aluminum laminate having high electrical insulation properties, high total reflectance, and high bending workability. As a result, it was confirmed that the aluminum laminate of the aluminum substrate 1 including the surface layer of the first surface 1A containing aluminum having a purity of 99.9 mass% or more and iron having a purity of 0.001 mass% or more and 0.02 mass% or less, the surface roughness Ra of the second surface 2A of the first anodic oxide film 2 being 15nm or less, and the thickness of the first anodic oxide film 2 in the intersecting direction being 2 μm or more and 20 μm or less has high electrical insulation properties and high total reflectance. The present inventors have also found that such bendability of the aluminum laminate, that is, the degree of difficulty in cracking during bending, is related to the value T1 of the total thickness of the aluminum laminate and the value T2 of the thickness of the first anodic oxide film 2 (details will be described later in examples).

The T1 and the T2 of the aluminum laminate 10 can be set arbitrarily as long as the thickness of the first anodic oxide film 2 is 2 μm or more and 20 μm or less and the relational expression T1+10 × T2 ≦ 230 is satisfied. From the viewpoint of improving the bending workability, the aluminum laminate 10 preferably satisfies T1+10 XT 2. ltoreq.200, more preferably T1+10 XT 2. ltoreq.150, and still more preferably T1+10 XT 2. ltoreq.100.

The lower limit of the above-mentioned T1+10 × T2 of the aluminum laminate 10 may be set so that the thickness T2 of at least the first anodic oxide film 2 in the intersecting direction can be 2 μm or more. The lower limit of the above-mentioned T1+10 × T2 may be, for example, 50.

In the aluminum laminate 10 shown in fig. 1, when the value of the thickness of the aluminum substrate 1 in the intersecting direction is T3 (unit: μm), the value T1 is expressed as the sum of the value T3 of the thickness of the aluminum substrate 1 and the value T2 of the thickness of the first anodic oxide film 2. The aluminum laminate 10 shown in FIG. 1 satisfies the relationship T3+11 XT 2 ≦ 230.

< method for producing aluminum laminate >

Next, an example of the method for producing an aluminum laminate according to the present embodiment will be described. As shown in fig. 2, the method for producing an aluminum laminate according to the present embodiment includes: the method for producing the aluminum base material includes a step (S50) of preparing an ingot (S10), a step (S20) of homogenizing the ingot, a step (S30) of hot-rolling the ingot, a step (S40) of cold-rolling a hot-rolled material obtained by the hot-rolling, a step (S50) of cold-rolling a cold-rolled material obtained by the cold-rolling in a final finishing form (hereinafter referred to as final finish cold-rolling), and a step (S60) of forming an anodic oxide film.

First, an ingot is prepared (step S10). Specifically, a melt of aluminum having a predetermined composition is prepared, and the melt of aluminum is solidified to cast an ingot (for example, semi-continuous casting). The content of the metal elements such as Fe, Mn, and Si in the melt is controlled so that the aluminum purity in the surface layer of the aluminum substrate 1 becomes 99.9 mass% or more. The content of Fe in the melt is controlled so that the content of Fe in the surface layer of the aluminum substrate 1 is 0.001 mass% or more and 0.02 mass% or less. The Fe content in the melt is preferably controlled so that the Fe content in the surface layer of the aluminum substrate 1 is 0.001 mass% or more and 0.02 mass% or less.

Subsequently, the obtained ingot is subjected to a homogenizing heat treatment (step (S20)). The homogenization heat treatment may be performed under a range of general operating conditions, for example, under conditions in which the heating temperature is 400 ℃ to 630 ℃ inclusive and the heating time is 1 hour to 20 hours inclusive.

Subsequently, the ingot is hot-rolled (step (S30)). Through this step, a hot-rolled material having a predetermined thickness W1 was obtained. The hot rolling may be performed 1 or more times. In the case of producing an aluminum ingot of a thin plate by continuous casting, the thin plate-like ingot may be cold-rolled without passing through this step.

Next, the hot rolled material obtained by the hot rolling is subjected to cold rolling (step (S40)). By this step, a cold rolled material having a predetermined thickness W2 (rolled material in the final finish cold rolling step (S50)) was obtained. In this step, cold rolling, for example, an intermediate annealing step is performed a plurality of times. For example, first, a first cold rolling step (S40A) is performed on a hot rolled material to form a rolled material that is thinner than the thickness W1 of the hot rolled material and thicker than the thickness W2 of the cold rolled material. Subsequently, the intermediate annealing step is performed on the obtained rolled material (S40B). The intermediate annealing may be performed under a range of general operating conditions, for example, under conditions in which the annealing temperature is 50 ℃ to 500 ℃ inclusive and the annealing time is 1 second to 20 hours inclusive. Next, the annealed rolled material is subjected to a second cold rolling step (S40C) to form a cold rolled material having a thickness W2.

Subsequently, the cold rolled material is subjected to final finish cold rolling (step (S50)). In this step, the material to be rolled is subjected to final finish cold rolling using a roll. The roll has a roll surface for rolling in contact with a material to be rolled. The surface roughness Ra of the roll surface of at least one of the pair of rolls arranged to sandwich the material to be rolled is preferably 50nm or less. When the material to be rolled is rolled by using a roll having a surface roughness of more than 50nm, the surface roughness Ra of the first surface of the obtained aluminum substrate becomes 20nm or more. The surface roughness Ra of the roll used in this step is preferably as small as possible, and more preferably 40nm or less. The aluminum substrate 1 is prepared in this manner.

Next, the first anodic oxide film 2 is formed on the first surface 1A of the obtained aluminum substrate 1 (step S60). The step (S60) may be performed by a generally known anodizing method. The anodic oxidation treatment is performed, for example, by: at least 1 selected from a sulfuric acid bath, a boric acid bath, an oxalic acid bath and a phosphoric acid bath is used as an electrolytic solution, the aluminum substrate 1 is immersed as an anode, and the other electrode immersed in the electrolytic solution is used as a cathode, and electricity is conducted between them. The conditions of the anodizing treatment are appropriately selected so that the thickness of the first anodic oxide film 2 is 2 μm to 20 μm and the surface roughness Ra of the second surface 2A is 15nm or less. A sulfuric acid bath is preferred for the electrolyte. In this way, the aluminum laminate 10 according to the present embodiment shown in fig. 1 can be obtained.

< modification example >

The surface layer of the aluminum substrate 1 including the first face 1A may not contain Si. As described above, Si contributes to the improvement of the mechanical strength of the aluminum substrate 1, but in the case where the required mechanical strength can be ensured by other parameters such as the thickness, the aluminum substrate 1 may not contain Si. In this case, the total content of the impurities other than Al and Fe constituting the balance in the surface layer including the first surface 1A of the aluminum substrate 1 may be 0.10 mass% or less.

As shown in fig. 3, the aluminum laminate 11 may further include a second anodic oxide film 3 provided so as to be in contact with the third surface 1B of the aluminum substrate 1. Second anodic oxide film 3 has fourth surface 3B located away from third surface 1B in the intersecting direction. That is, the aluminum laminate 11 includes the aluminum substrate 1, and the first anodic oxide film 2 and the second anodic oxide film 3 provided so as to sandwich the aluminum substrate 1.

In the aluminum laminate 11 shown in fig. 3, the value T1 of the total thickness is represented by the sum of the value T3 (unit: μm) of the thickness of the aluminum substrate 1, the value T2 (unit: μm) of the thickness of the first anodic oxide film 2, and the value T4 (unit: μm) of the thickness of the second anodic oxide film 3 in the intersecting direction. The thickness of the second anodic oxide film 3 is equal to or less than the thickness of the first anodic oxide film 2. The thickness of the second anodic oxide film 3 is 2 μm or more and 20 μm or less.

The aluminum laminate 11 satisfies the relationship T1+10 XT 2 ≦ 230. That is, the aluminum laminate 11 satisfies the relationship T1+10 XT 4. ltoreq.T 1+10 XT 2. ltoreq.230. The aluminum laminate 11 satisfying the above relational expression can exhibit the same effects as those of the aluminum laminate 10 according to embodiment 1, and has high bending workability. Preferably, the aluminum laminate 11 satisfies the relation T1+10 (T2+ T4). ltoreq.230.

In the aluminum laminate 11, the surface layer including the third surface 1B of the aluminum substrate 1 has an aluminum purity of 99.9 mass% or more, and includes 0.001 mass% or more and 0.02 mass% or less of iron, as in the surface layer including the first surface 1A. Such an aluminum substrate 1 can be prepared by the same method as the above-described steps (S10) to (S50) of the above-described method for producing an aluminum laminate 10.

In the aluminum laminate 11, the second anodic oxide film 3 has a surface roughness Ra of 15nm or less in the fourth surface 3B, as in the first anodic oxide film 2. Such a second anodic oxide film 3 can be formed by the same method as the above-described step (S60) of the above-described method for producing an aluminum laminate 10. In such an aluminum laminate 11, the second surface 2A of the first anodic oxide film 2 and the fourth surface 3B of the second anodic oxide film 3 have high glossiness and high total reflectance.

In the aluminum laminate 11, the composition of the surface layer including the third surface 1B of the aluminum substrate 1 may be different from the composition of the surface layer including the first surface 1A, but is preferably the same. The aluminum substrate 1 may have a different composition for each of the surface layer including the first surface 1A and the surface layer including the third surface 1B and for the intermediate layer interposed therebetween, such as a clad material, for example.

As shown in fig. 4, the aluminum laminate manufacturing method may further include a step (S70) of polishing the aluminum substrate obtained by final finish cold rolling after the step (S50) and before the step (S60). In this step (S70), the surface of the aluminum substrate to be the first surface 1A is polished to form the aluminum substrate 1 having the first surface 1A. In the above-described method for producing the aluminum laminate 11, the surface to be the first surface 1A and the surface to be the third surface 1B are polished to form the aluminum substrate 1 having the first surface 1A and the third surface 1B. The polishing method may be selected from physical polishing, electrolytic polishing, chemical polishing, and the like, but is not limited thereto.

In the method for producing an aluminum laminate, after the step (S50) and before the step (S60), a step of forming an aluminum substrate obtained by final finish cold rolling into a predetermined shape may be performed. Alternatively, after the step (S60), the step of molding the

aluminum laminate

10 or 11 obtained in the step (S60) may be performed. After the step (S60), a step of forming a film on at least 1 surface of the aluminum laminate 10, for example, on the third surface 1B of the aluminum substrate 1, may be performed. The material constituting the coating film is at least 1 selected from the group consisting of resins, metals, ceramics, and the like. The coating is, for example, an adhesive layer, and after the step of forming the coating, a step of adhering the aluminum laminates 10 and 11 to another member or a wall or the like via the coating may be performed. After the step (S60), the pores of at least one of the first anodic oxide film 2 and the second anodic oxide film 3 of the aluminum laminates 10 and 11 obtained in the step (S60) may be subjected to coloring treatment and sealing treatment, or only sealing treatment may be performed. The coloring treatment may be any method, and may be, for example, a method of adsorbing a dye or a pigment, or a secondary electrolytic coloring method.

Examples

Samples of the aluminum laminates of examples and comparative examples of the present embodiment were produced in the manner described below, and their glossiness, total reflectance, bending workability, and dielectric breakdown voltage were evaluated.

[ Table 1]

[ Table 2]

First, aluminum substrates of examples and comparative examples were produced by the following production steps using aluminum having different aluminum purities and Fe contents shown in tables 1 and 2.

An ingot of aluminum obtained by DC casting was subjected to a homogenization heat treatment in a heating furnace. Then, hot rolling was performed until the thickness became about 6.5 mm. The obtained hot rolled material was subjected to cold rolling a plurality of times until the thickness became a predetermined value. The aluminum substrate was subjected to multiple cold rolling with intermediate annealing to prepare aluminum substrates having thicknesses shown in tables 1 and 2.

In this case, in examples 1 to 10 and comparative examples 1 to 9 and 12 to 18, the final finish cold rolling was performed using a roll having a surface roughness Ra of 40 nm. In comparative examples 10 and 11, the final finish cold rolling was performed using a roll having a surface roughness Ra of 50 nm. In comparative examples 19 to 21, the final finish cold rolling was performed using a roll having a surface roughness Ra of 150 nm.

The homogenization heat treatment was performed on each sample under conditions of a heating temperature of 400 ℃ to 630 ℃ and a heating time of 1 hour to 20 hours. For each sample, the intermediate annealing is performed under conditions such that the annealing temperature is 50 ℃ to 500 ℃ inclusive, and the annealing time is 1 second to 20 hours inclusive. The surface roughness Ra of the first surface of the aluminum substrate of each example is 15nm or less.

The obtained aluminum substrate was subjected to anodic oxidation treatment in the above manner. The electrolyte was an aqueous solution containing 15 vol% of sulfuric acid and having a bath temperature of 21 ℃. Each sample was immersed in the electrolyte as an anode, and a current density of 130mA/m was passed between the anode and a cathode for a predetermined time²The anodic oxidation treatment is performed. The time for the anodization of each sample was set to a time at which an anodized coating layer having a predetermined thickness could be obtained. That is, the conditions for the anodization treatment were the same for each sample except for the anodization treatment time.

Further, the entire sample was subjected to a sealing treatment. The sealing treatment of examples 2 to 10 and comparative examples 2 and 4 to 21 was performed by immersing each sample on which an anodic oxide film was formed in an aqueous solution containing nickel acetate at a concentration of 5g/L and boric acid at a concentration of 5g/L and having a bath temperature of 90 ℃ for 20 minutes, and then in pure water at a temperature of 98 ℃ for 20 minutes. The sealing treatment of example 1 and comparative examples 1 and 3 was performed by immersing in pure water at a temperature of 66 ℃ for 5 minutes.

Each sample prepared in this manner was evaluated by the following evaluation method. The evaluation results are shown in tables 1 to 4.

< evaluation method >

The thickness of the obtained anodic oxide film was measured by the following measurement method using Filmetrics F20 manufactured by VITEC co. The reflectance spectrum in the wavelength region from 400nm to 1100nm is obtained from the reflected light obtained when the visible light is irradiated onto the third surface of the aluminum laminate. The obtained reflectance spectrum is fitted so as to have the same wavelength as the theoretical spectrum of the valley or peak of the interference portion, and the film thickness is derived.

The dielectric breakdown voltage was measured using YST-243-30RO, a dielectric breakdown testing device manufactured by YAMAYO TESTER CORPORATION. The voltage at the time when the current was applied to the 2A surface of the test piece cut into 50mm X50 mm and the current of 5mA or more was applied to the 1B surface was defined as the insulation breakdown voltage. The voltage was increased at a rate of 50V/sec.

The cell size admittance Y value was measured according to JIS H8683 (2013 edition). The value of pore sealing degree admittance Y was measured by using ANOTESTYMP30-S manufactured by Fischer Instruments, and the measurement area was set to 28.26mm²Admittance of the time.

Surface unevenness was observed by an atomic force microscope using a scanning probe microscope AFM5000II manufactured by Hitachi High-Tech Science, Inc., and a surface shape was observed in a dynamic force mode (non-contact) in a rectangular field of view of 80 μm × 80 μm. The obtained observation results were subjected to least square approximation to obtain a curved surface, and the inclination of the sample was corrected by automatic inclination correction using a 3-order curved surface subjected to fitting, thereby measuring the surface roughness Ra. The surface roughness Ra is a value calculated by extending the arithmetic average roughness Ra defined by JIS B0601(2001 edition) and ISO4287(1997 edition) into three dimensions so as to be applicable to the entire observed surface.

The Gloss was measured at a light incidence angle of 60 ℃ using a Gloss meter VG7000 manufactured by Nippon Denshoku industries Co., Ltd. The measurement of the gloss was performed in two directions, namely, a Rolling Direction (RD) and a direction (TD) perpendicular to the rolling direction, and the value in each direction was evaluated. The higher the glossiness, the more metallic luster feeling is obtained.

The total reflectance was measured in an integrating sphere in a wavelength range of 250nm to 2000nm using an ultraviolet-visible spectrophotometer V570 manufactured by Nippon corporation, using a standard white plate Spectralon for an integrating sphere manufactured by Labsphere corporation as a reference. The average value of visible light in the wavelength region of 400nm to 800nm is determined from the obtained total reflectance measurement value. The total reflectance was measured in two directions, namely, the Rolling Direction (RD) and The Direction (TD) perpendicular to the rolling direction, and the total reflectance was evaluated as the average value of these.

The bending workability was evaluated by observing each sample subjected to the bending workability described above for the presence or absence of cracks in each anodic oxide film.

Specifically, the test pieces of the examples and comparative examples were cut out by 100mm in the Rolling Direction (RD) and by 15mm in The Direction (TD) perpendicular to the rolling direction. Further, a plurality of cylinders having diameters different in steps are prepared. Next, each of the cut small pieces was held along the outer peripheral surface of the cylinder having the longest diameter for 10 seconds. Next, the surface of the anodized film after the bending was visually observed. No cracks were observed in the anodic oxide film by visual observation, and the surface of the anodic oxide film was visually observed after holding the film for 10 seconds along the outer peripheral surface of a cylinder having a diameter shorter than that of a cylinder used in the past. In this manner, the bending and the evaluation were performed using a cylinder having a shorter diameter in stages without any crack being observed in the anodic oxide film. The minimum diameter in tables 3, 4 indicates: in each test piece, the minimum value (unit: mm) of the diameter of the cylinder used for the bending processing in which cracks were not observed in the anodic oxide film was determined.

< evaluation results >

[ Table 3]

[ Table 4]

Examples 1 to 10 each had an aluminum base material having an aluminum purity of 99.9 mass% or more and containing 0.001 mass% or more and 0.02 mass% or less of iron; and an anodic oxide film having a surface roughness Ra of 15nm or less and a thickness of 2 μm or more and 20 μm or less, and satisfying the above relational expression. The insulation breakdown voltage of the anodic oxide film of examples 1 to 10 was 0.2kV or more. The insulation breakdown voltage was 0.2kV or more in examples 1 to 6 and 8 in which the thickness of the anodic oxide film was 2 μm or more and less than 9 μm.

In contrast, comparative examples 2, 6, and 7 differ from examples 1 to 10 only in that the above-described 5 parameters, that is, the aluminum purity and the iron content of the aluminum substrate, the surface roughness and the thickness of the anodic oxide film, and the above-described relational expression are less than 2 μm in the thickness of the anodic oxide film. The insulation breakdown voltage of the anodic oxide films of comparative examples 2, 6, and 7 was less than 0.2 kV.

In comparative examples 14 and 15, the above 5 parameters are different from those in examples 1 to 10 only in that the iron content in the aluminum base material exceeds 0.02 mass%. Is an aluminum laminate. The insulation breakdown voltage of the anodic oxide films of comparative examples 14 and 15 was less than 0.2 kV.

In comparative example 19, the 5 parameters are different from those in examples 1 to 10 only in that the surface roughness Ra of the second surface exceeds 15 nm. The insulation breakdown voltage of the anodic oxide film of comparative example 19 was less than 0.2 kV.

The thickness of the anodic oxide film of example 1 was 4.7 μm, and the pore sealing admittance Y value exceeded 100. mu.S. The thickness of the anodic oxide films of examples 2, 4, 5 and 10 was 2 μm or more and 3 μm or less, and the pore sealing tolerance Y value was less than 100 μ S. In contrast, in comparative examples 1 and 3, the 5 parameters were the same as in examples 1 to 10, but were different from examples 2 to 10 only in that the value of the pore sealing tolerance Y exceeded 100 μ S. In particular, in example 4, the sealing degree of only the anodic oxide film is different from that in comparative example 3, and in example 4, the value of the pore admittance Y is lower than that in comparative example 3, that is, the sealing degree is higher. The insulation breakdown voltage of the anodic oxide films of examples 1 to 10 was 0.2kV or more as described above, while the insulation breakdown voltage of the anodic oxide films of comparative examples 1, 3, and 18 was less than 0.2 kV.

From the above results, it was confirmed that the insulation breakdown voltage of the anodic oxide film on the aluminum substrate depends on the thickness of the anodic oxide film and the iron content of the aluminum substrate rather than the degree of sealing of the anodic oxide film, and the lower limit of the thickness of the anodic oxide film and the lower limit of the iron content of the aluminum substrate should be set to 2 μm and 0.02 mass% so that the insulation breakdown voltage is 0.2kV or more.

It was also confirmed that when the thickness of the anodic oxide film is small, 2 μm or more and 3 μm or less, the insulation breakdown voltage of the anodic oxide film on the aluminum substrate depends on the sealing degree, and the upper limit of the sealing degree admittance Y value should be set to 100 μ S in order to set the insulation breakdown voltage to 0.2kV or more.

The inventors of the present invention have found that the shortest value (unit: mm) of the diameter of the cylinder used for the bending in which no crack was observed in the anodic oxide film in the bending test is related to the value T1+10 × T2 when the value of the total thickness of the aluminum base material and the anodic oxide film in the intersecting direction is T1 and the value of the thickness of the anodic oxide film in the intersecting direction is T2 for each of the samples of examples 1 to 10 and comparative examples 1 to 21. The correlation coefficient R2 exceeds 0.92. In examples 1 to 10 satisfying the above relational expressions, cracks were not observed in the first anodic oxide film 2 even when bending was performed at least along the outer peripheral surface of a cylinder having a diameter of 50 mm. In examples 1 to 6 and 8 in which the value T1 was less than 9 μm and the value T1+10 × T2 was 150 or less, no cracks were observed in the first anodic oxide film 2 even when the bending was performed along the outer peripheral surface of a cylinder having a diameter of 32 mm. Further, in examples 6 and 8 in which the value T1+10 × T2 was 100 or less, no cracks were observed in the first anodic oxide film 2 even when bending was performed along the outer peripheral surface of a cylinder having a diameter of 16 mm.

On the other hand, in comparative examples 4, 5, 8, 9, 11 to 13, 15, and 21 which did not satisfy the above relational expression, cracks were observed in the anodic oxide film when bending was performed along the outer peripheral surface of a cylinder having a diameter of 50mm or more.

The present inventors have confirmed that even a thick aluminum laminate having an anodic oxide film thickness T2 of 2 μm or more can achieve high bending workability if the above relational expression is satisfied.

For example, the thickness of the anodic oxide film in example 6 is the same as in comparative examples 8 and 9, but the thickness of the aluminum substrate is 100 μm or more thinner than in comparative examples 8 and 9. In example 6 satisfying the above relational expression, no crack was observed even when the outer periphery of the cylinder having the minimum diameter of 25mm was wound in the bending test. On the other hand, in comparative examples 8 and 9 which did not satisfy the above relational expression, cracks were observed when the outer circumference of a cylinder having a diameter of 50mm was wound in a bending test.

The present inventors considered that the

coefficients

1 and 10 of the left T1+10 × T2 in the above relational expression relate to the difference in the degree of influence of the aluminum substrate and the anodic oxide film on the bending workability. The anodic oxide film has lower ductility than an aluminum substrate. Therefore, the anodic oxide film is considered to have a higher influence on bending workability than the aluminum substrate. For example, when the thickness of the aluminum laminate is increased or decreased by several tens μm and the increase or decrease is caused by the increase or decrease in the thickness of the aluminum base material, the bending workability is not greatly changed by the increase or decrease. In contrast, when the thickness of the aluminum laminate is increased or decreased by several tens μm and the increase is caused by the increase or decrease in the thickness of the anodic oxide film, the bending workability is greatly changed by the increase or decrease. This is shown in the present evaluation results.

In addition, the gloss in the RD direction and the TD direction in examples 1 to 10 was 63% or more, and the total reflectance of visible light was 83% or more, and the gloss and the total reflectance were high. In contrast, in comparative examples 10, 11, 16, 17, and 19 to 21, at least either one of the glossiness and the total reflectance of visible light does not satisfy the above numerical range.

The anodized films of comparative examples 16 and 17, in which the aluminum purity of the aluminum base material was less than 99.9 mass% and the Fe content of the aluminum base material was more than 0.052 mass%, had a surface roughness Ra of more than 15nm, a glossiness of less than 63%, and a total visible reflectance of less than 83%, and did not have high glossiness and high total reflectance. In comparative example 6 in which the thickness of the anodic oxide film was less than 1 μm, the total reflectance for visible light was less than 83%, and the total reflectance was not high. In addition, the surface roughness Ra of the anodic oxide coating exceeds 15nm, and the glossiness of the comparative examples 10, 11, 19 to 21 is less than 63%, the total reflectance of visible light is less than 83%, and the high glossiness and the high total reflectance are not provided.

From the above results, it was confirmed that according to the present embodiment, an aluminum laminate having high electrical insulation properties and high bending workability, and having high glossiness and high total reflectance can be provided. The aluminum laminate according to the present embodiment is particularly suitable for a substrate of an electronic device constituting a display such as a liquid crystal display, an organic EL display, an electronic paper, a thin-film solar cell, and a touch panel.

The presently disclosed embodiments and examples are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is not intended to be limited to the above embodiments and examples, but is to be defined by the claims, and all modifications and variations that fall within the meaning and scope equivalent to the claims are intended to be embraced therein.

Description of the reference numerals

1 aluminum substrate, 1A first surface, 1B third surface, 2 first anodic oxide film, 2A second surface, 3 second anodic oxide film, 3B fourth surface, 4 substrate, 10, 11 aluminum laminate.

Claims

1. An aluminum laminate comprising:

an aluminum substrate having a first face; and

a first anodic oxide film formed in contact with the first surface and having a second surface located away from the first surface in a direction intersecting the first surface,

a surface layer of the aluminum base material including the first surface contains aluminum having a purity of 99.9 mass% or more and iron having a purity of 0.001 mass% or more and 0.02 mass% or less,

the surface roughness Ra of the second surface of the first anodic oxide coating is 15nm or less,

the first anodic oxide film has a thickness of 2 to 20 [ mu ] m in the direction intersecting the first anodic oxide film,

the relation between the total value T1 of the thicknesses of the aluminum substrate and the first anodic oxide film in the intersecting direction and the value T2 of the thickness of the first anodic oxide film in the intersecting direction is T1+10 XT 2 ≦ 230, wherein the units of T1 and T2 are μm,

the hole sealing degree admittance Y value of the first anodic oxide coating is less than 100 mu S.

2. An aluminum laminate comprising:

an aluminum substrate having a first face; and

the first anodic oxide film has a thickness of 3 to 20 [ mu ] m in the direction intersecting the first anodic oxide film,

the relationship between the total value T1 of the thicknesses of the aluminum substrate and the first anodic oxide film in the intersecting direction and the value T2 of the thickness of the first anodic oxide film in the intersecting direction is T1+10 XT 2 ≦ 230, wherein the unit of T1 and T2 is μm.

3. The aluminum laminate as recited in claim 2,

4. The aluminum laminate according to any one of claims 1 to 3,

the first anodic oxide film has an insulation breakdown voltage of 0.2kV or more.

5. The aluminum laminate according to any one of claims 1 to 4,

the first anodic oxide coating is a sulfuric acid anodic oxide coating.

6. A method for producing an aluminum laminate,

a method for producing the aluminum laminate according to any one of claims 1 to 5, comprising the steps of:

preparing the aluminum substrate having a surface roughness Ra of 15nm or less on the first surface; and

and forming a first anodic oxide film having a thickness of 2 to 20 μm in the cross direction on the first surface of the aluminum substrate using an electrolytic solution containing sulfuric acid.