Aluminum Laminate

Abstract

To provide a metal laminate which has excellent electromagnetic shield characteristics and bending characteristics against repeated bending.SOLUTION: There is provided an aluminum laminate for an electromagnetic shield tape in which at least a resin film and an aluminum foil are stacked, wherein a thickness t1 of the aluminum foil is 40% or more and 60% or less with respect to a thickness t0 of the aluminum laminate, 0.2% bearing force in a roll processing direction of the aluminum laminate is larger than 50.0 N / mm2, breaking elongation in the roll processing direction of the aluminum laminate is 30.0% or more, and a width distortion ratio in a roll processing width direction of the aluminum laminate is 0.60 or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an aluminum laminate having excellent flexibility. [Background technology]

[0002] With the recent development of information and communication technology, devices that emit electromagnetic waves are being used in a variety of fields. For example, with the development of AI technology, various sensors and controls are being used extensively, as exemplified by the operation of devices by robots and autonomous driving in the automobile industry.

[0003] On the other hand, the generation of electromagnetic waves that cause noise is also increasing, for example, when electric vehicles are driven by AC motors as a power source. For this reason, it is important to prevent malfunctions caused by exposure to electromagnetic waves in various control devices, sensors, and the cables that connect them, and there is a need to apply electromagnetic wave shielding to various electric wires and cables.

[0004] For example, as a means for providing electromagnetic wave shielding to electric cables, electromagnetic wave shielding materials described in JP 2019-176022 A (Patent Document 1) and JP 2013-065675 A (Patent Document 2) are known.

[0005] The electromagnetic wave shielding material described in Patent Document 1 is wrapped around an electric wire or cable to provide electromagnetic wave shielding, and contains a layer made of a metal foil such as copper foil or aluminum foil as all or part of the structure to provide high electromagnetic wave shielding properties. However, although the electromagnetic wave shielding material described in Patent Document 1 has excellent electromagnetic wave shielding properties, it has a problem of poor flexibility, particularly with respect to repeated bending, making it difficult to use.

[0006] On the other hand, the electromagnetic wave shielding material described in Patent Document 2 is a sheet-like electromagnetic wave shielding material applied to a flat cable, but since it does not include a layer made of metal foil, there is a problem that although it has excellent flexibility against repeated bending, it does not provide high-level electromagnetic wave shielding properties.

[0007] Furthermore, in recent years, as mentioned above, sensors and control devices are being attached to devices in various fields, and the electric wires and cables connecting them are increasingly being used in moving parts that are subject to severe repeated bending, such as the arm joints of robots, or the door mirrors and door opening / closing parts of in-vehicle devices.

[0008] For this reason, electromagnetic shielding materials applied to electric wires and cables are required to have high bending properties that can withstand repeated bending more than ever before. However, as described above, in order to improve the bending properties of electromagnetic shielding materials against repeated bending, the electromagnetic shielding layer must be made thin or rough by using a metal layer formed by vapor deposition or a resin layer containing conductive particles, which poses an essential problem of not being able to obtain sufficient electromagnetic shielding properties. On the other hand, when an attempt is made to ensure excellent electromagnetic shielding properties by using a metal foil for the electromagnetic shielding layer, there is also an essential problem of not being able to obtain high bending properties against repeated bending. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2019-176022 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-065675 Summary of the Invention [Problem to be solved by the invention]

[0010] Therefore, an object of the present invention is to provide a metal laminate for electromagnetic wave shielding tape that is lightweight, has excellent electromagnetic wave shielding properties, includes a metal foil that can be wrapped around a cable, and yet exhibits excellent bending properties against repeated bending. [Means for solving the problem]

[0011] The present inventors have conducted extensive research into materials that exhibit high electromagnetic wave shielding properties, materials that exhibit high bending properties against repeated bending, and combinations of these materials. As a result, they have found that in a laminate in which a resin film is laminated to an aluminum foil used as the main material of an electromagnetic wave shielding material, the bending properties against repeated bending are significantly improved when the thickness ratio of the aluminum foil in the laminate is within a specific range and the 0.2% proof stress, breaking elongation, and width strain ratio in the rolling direction of the laminate are higher than specific values, thereby completing the present invention.

[0012] That is, according to the present invention, in an aluminum laminate in which at least a resin film and an aluminum foil are laminated, the thickness t1 of the aluminum foil is 40% or more and 60% or less of the thickness t0 of the aluminum laminate, and the 0.2% proof stress in the rolling direction of the aluminum laminate is 50.0 N / mm 2 the breaking elongation in the rolling direction of the aluminum laminate is 30.0% or more, and the width strain ratio in the rolling width direction of the aluminum laminate is 0.60 or more.

[0013] The aluminum laminate of the present invention has a basic structure in which at least one resin film layer is laminated on an aluminum foil. Furthermore, in the present invention, the ratio of the aluminum foil thickness t1 to the aluminum laminate thickness t0 and the 0.2% proof stress in the rolling direction of the aluminum laminate are limited because, if these values ​​fall outside the above ranges, when the aluminum laminate is bent or repeatedly bent, part of the aluminum foil in the laminate will not be able to withstand deformation, resulting in early fracture and failure to obtain good electromagnetic wave shielding properties. Therefore, the aluminum laminate of the present invention achieves two seemingly contradictory properties: high electromagnetic wave shielding properties while achieving high bending properties against repeated bending.

[0014] In the aluminum laminate of the present invention, the aluminum foil has a diffraction intensity I 1 indicating the (200) plane relative to a total diffraction intensity I 0 , which is the sum of the diffraction intensities indicating each of the (111) plane, the (200) plane, the (220) plane, and the (311) plane, in X-ray diffraction. 200 The ratio P 200 is 30% or more and 60% or less, and the diffraction intensity I indicating the (220) plane is 220 The ratio P 220 is preferably 10% or more and 40% or less.

[0015] Diffraction intensity showing the (200) plane of aluminum foil I 200 The ratio P 200 and diffraction intensity showing (220) plane I 220 The ratio P 220 By limiting the value of the thickness of the laminate to within the above range, it is possible to impart excellent bending properties to the aluminum laminate with respect to repeated bending.

[0016] In the aluminum laminate of the present invention, the aluminum foil preferably contains 0.4 mass % to 1.7 mass % of iron.

[0017] If the iron content in the aluminum foil is less than 0.4% by mass, it becomes difficult to refine the crystal grains in the aluminum foil, resulting in insufficient strength of the aluminum foil and an increase in the occurrence of pinholes after cold rolling. On the other hand, if the iron content is more than 1.7% by mass, coarse intermetallic compounds are likely to occur, which reduces workability and also makes pinholes more likely to occur.

[0018] In the aluminum laminate of the present invention, the thickness of the aluminum foil of each layer is preferably 5 μm or more and 300 μm or less, more preferably 5 μm or more and 150 μm or less, and even more preferably 6 μm or more and 80 μm or less.

[0019] When the thickness of the aluminum foil is within the above-mentioned range, the aluminum laminate of the present invention can be easily wrapped around even an object with an extremely small radius of curvature, such as a cable, without causing breakage, and also makes it possible to form an electromagnetic wave shielded cable without impairing flexibility against repeated bending.

[0020] In the aluminum laminate of the present invention, the resin film and the aluminum foil are laminated via an adhesive, and the peel strength between the resin film and the aluminum foil is preferably 3.0 N / 15 mm or more.

[0021] If the peel strength between the resin film and the aluminum foil is less than 3.0 N / 15 mm, when the resin film is subjected to bending deformation due to repeated bending, the deformation of the aluminum foil will not be able to adequately follow the deformation of the resin film, and the aluminum foil itself may be excessively deformed locally and break.

[0022] In the present invention, a resin film suitable for effectively improving the flexural properties while maintaining the electromagnetic wave shielding effect of aluminum foil preferably contains at least a polyester resin such as a polyethylene terephthalate resin.

[0023] Furthermore, the aluminum laminate of the present invention may further be laminated with a printed layer or a coated layer from the viewpoint of improving convenience and decorativeness. [Effects of the Invention]

[0024] The aluminum laminate of the present invention is formed by laminating an aluminum foil with a resin film, setting the thickness t1 of the aluminum foil to 40% or more and 60% or less of the thickness t0 of the aluminum laminate, and setting the 0.2% yield strength of the aluminum laminate in the rolling direction to 50.0 N / mm 2 By making the breaking elongation of the aluminum laminate in the rolling direction greater than 30.0% and the width strain ratio of the aluminum laminate in the rolling width direction greater than 0.60, it is possible to achieve extremely excellent bending properties against repeated bending while maintaining high electromagnetic wave shielding properties. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a cross-sectional view schematically illustrating a laminate structure of an aluminum laminate according to a first embodiment of the present invention. [Figure 2] FIG. 4 is a cross-sectional view schematically showing the laminate structure of an aluminum laminate according to a second embodiment of the present invention. [Figure 3] FIG. 10 is a cross-sectional view schematically illustrating a laminate structure of an aluminum laminate according to a third embodiment of the present invention. [Figure 4] FIG. 10 is a cross-sectional view schematically showing the laminate structure of an aluminum laminate according to a fourth embodiment of the present invention. [Figure 5] FIG. 10 is a cross-sectional view schematically showing the laminate structure of an aluminum laminate according to a fifth embodiment of the present invention. [Figure 6] FIG. 10 is a cross-sectional view schematically showing the laminate structure of an aluminum laminate according to a sixth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] An aluminum laminate according to one embodiment of the present invention will be described in detail below with reference to the drawings. Note that the present invention is not limited to the examples shown below, and various modifications are possible within the scope of the technical concept of the present invention.

[0027] <Basic structure of aluminum laminate> FIG. 1 shows a cross-sectional view of an aluminum laminate 1a in which one resin film (layer) 3 is laminated onto one aluminum foil (layer) 2 via an adhesive (layer) 4, as a first embodiment of the present invention.

[0028] 1, the aluminum laminate 1a of this embodiment is formed by laminating at least a resin film (layer) 3 and an aluminum foil (layer) 2. If the aluminum foil (layer) 2 were a single body, the flexural properties would be significantly reduced with respect to repeated bending, so by laminating the aluminum foil (layer) 2 and at least one or more resin film (layer) 3, the reduction in flexural properties is prevented or improved.

[0029] Furthermore, it is preferable that the aluminum laminate 1a further includes an adhesive (layer) 4 between the aluminum foil (layer) 2 and the resin film (layer) 3. In this embodiment, the aluminum foil (layer) 2 and the resin film (layer) 3 are firmly bonded together via the adhesive (layer) 4, making it more suitable for use as an electromagnetic wave shielding material for covering electric wires and cables with an extremely small radius of curvature. Note that the aluminum foil (layer) 2 and the resin film (layer) 3 of this embodiment do not necessarily need to be laminated together via the adhesive (layer) 4; the aluminum foil (layer) 2 and the resin film (layer) 3 may be directly laminated together, for example, by heat fusion or the like.

[0030] Fig. 2 shows a cross-sectional view of an aluminum laminate 1b as a second embodiment, in which a printed layer 5 or a coating layer 5 is laminated on the aluminum foil (layer) 2 of the laminate 1a of the first embodiment, and Fig. 3 shows a cross-sectional view of an aluminum laminate 1c as a third embodiment, in which a printed layer 5 or a coating layer 5 is laminated on the resin film (layer) 3 of the laminate 1a of the first embodiment. Fig. 4 shows a cross-sectional view of an aluminum laminate 1d as a fourth embodiment, in which a second resin film (layer) 3 is further laminated on the aluminum foil (layer) 2 of the laminate 1a of the first embodiment via an adhesive (layer) 4.

[0031] In the present invention, like the aluminum laminates 1b and 1c of the second and third embodiments, the aluminum laminate 1a of the first embodiment may be used as a basic configuration, and a printed layer 5 or a coated layer 5 may be further laminated on the aluminum foil (layer) 2 or the resin film (layer) 3. Furthermore, although not shown, the printed layer 5 or the coated layer 5 may be laminated on both the aluminum foil (layer) 2 and the resin film (layer) 3 of the laminate 1a of the first embodiment.

[0032] In the present invention, as in the aluminum laminate 1d of the fourth embodiment, the aluminum laminate 1a of the first embodiment may be used as a basic configuration, and a second resin film (layer) 3 may be further laminated on the aluminum foil (layer) 2 via an adhesive (layer) 4. In other words, the aluminum laminate 1d of the fourth embodiment has resin films (layers) 3 on both one side and the other side of the aluminum foil (layer) 2. Note that, in the second to fourth embodiments, the aluminum foil (layer) 2 and the resin film (layer) 3 do not necessarily have to be laminated via the adhesive (layer) 4, as in the first embodiment.

[0033] Figure 5 shows a cross-sectional view of an aluminum laminate 1e as a fifth embodiment, in which a second aluminum foil (layer) 2 is laminated on top of the resin film (layer) 3 of the laminate 1a of the first embodiment via an adhesive (layer) 4, and Figure 6 shows a cross-sectional view of an aluminum laminate 1f as a sixth embodiment, in which a second resin film (layer) 3 is laminated on top of either side of the two aluminum foil (layers) 2 of the laminate 1e of the fifth embodiment via an adhesive (layer) 4.

[0034] In the present invention, as in the aluminum laminate 1e of the fifth embodiment, the aluminum laminate 1a of the first embodiment may be used as a basic configuration, and a second aluminum foil (layer) 2 may be further laminated on the resin film (layer) 3 via an adhesive (layer) 4. In other words, the aluminum laminate 1e of the fifth embodiment is an embodiment in which not only is the aluminum foil (layer) 2 laminated on one side of the resin film (layer) 3, but also the second aluminum foil (layer) 2 is further laminated on the other side of the resin film (layer) 3 on which the aluminum foil (layer) 2 is not laminated.

[0035] In the present invention, as in the aluminum laminate 1f of the sixth embodiment, the aluminum laminate 1a of the first embodiment may be used as a basic configuration, and other aluminum laminates 1a of the first embodiment may be repeatedly laminated on top of it so that the same material layers do not overlap. Note that in the fifth and sixth embodiments, the aluminum foil (layer) 2 and the resin film (layer) 3 do not necessarily have to be laminated via the adhesive (layer) 4, as in the first to fourth embodiments.

[0036] <0.2% yield strength in the rolling direction of aluminum laminate> The aluminum laminates 1a to 1f of this embodiment have a 0.2% yield strength in the rolling direction of 50.0 N / mm 2 The 0.2% yield strength in the rolling direction is 50.0 N / mm 2 If the thickness is less than this, the aluminum laminates 1a to 1f will break early when subjected to repeated bending accompanied by flexing, and good electromagnetic wave shielding properties will not be obtained.

[0037] Although the detailed mechanism is unclear, it is presumed as follows. For example, the aluminum laminates 1a to 1f of this embodiment, which are formed into a tape shape, are usually coated by deforming them to form a U-shape or an O-shape (rather than being wrapped around a cable in a spiral). Therefore, when the cable is repeatedly bent, the laminate is subjected to alternating compressive stress on the side with the smaller radius of curvature and tensile stress on the side with the larger radius of curvature. On the other hand, since the aluminum laminates 1a to 1f of this embodiment are made of a composite material made of a metal material and a resin material, when the above-mentioned bending is repeated, the resin film (layer) 3 basically undergoes repeated elastic deformation within the laminate, but the aluminum foil (layer) 2 is thought to repeatedly undergo plastic deformation exceeding its elastic limit from an early stage.

[0038] Therefore, if the 0.2% yield strength in the roll processing direction of the aluminum laminates 1a to 1f is small, the aluminum foil (layer) 2 in the aluminum laminates 1a to 1f will easily change from elastic deformation to plastic deformation, resulting in a high rate of bending in the plastic deformation region, which is thought to cause so-called metal fatigue and easy fracture.

[0039] In the present invention, the "rolling direction" refers to the processing direction when laminating a resin film onto an aluminum foil by a roll-to-roll method. In this embodiment, unless otherwise specified, the aluminum laminates 1a to 1f are laminated such that the rolling direction of the aluminum foil 2 during rolling and the flow direction of the resin material during molding of the resin film 3 are aligned with the rolling direction in order to improve the mechanical strength in the longitudinal direction.

[0040] <Thickness ratio of aluminum foil (layer) in aluminum laminate> The aluminum laminates 1a to 1f of this embodiment are characterized in that the thickness t1 of the aluminum foil (layer) 2 is 40% or more and 60% or less of the thickness t0 of the aluminum laminate. If the ratio of the thickness t1 of the aluminum foil (layer) 2 to the thickness t0 of the aluminum laminate is less than 40%, not only will the cross-sectional area (section modulus) of the aluminum foil (layer) 2 in the aluminum laminate be insufficient, but also the aluminum foil (layer) 2 that deviates from the neutral plane of the aluminum laminates 1a to 1f will be subject to large deformation when subjected to bending deformation. Therefore, among the large deformations allowed by the resin film (layer) 3, the aluminum foil (layer) 2 will reach its breaking strength first and break, resulting in poor electromagnetic wave shielding properties.

[0041] On the other hand, if the ratio of the thickness t1 of the aluminum foil (layer) 2 exceeds 60%, the thickness of the aluminum foil (layer) 2 in the aluminum laminate becomes excessive, and when the aluminum laminates 1a to 1f are bent, the aluminum foil (layer) 2 will have a surface on the side with a smaller radius of curvature that is subjected to compressive stress and a surface on the side with a larger radius of curvature that is subjected to tensile stress. Therefore, particularly with repeated bending, the aluminum foil (layer) 2 will suffer from early metal fatigue and will easily break even with small stresses and small deformations (strains), making it impossible to obtain good electromagnetic wave shielding properties.

[0042] <Fracture elongation in the rolling direction of aluminum laminate> The aluminum laminates 1a to 1f of this embodiment have the property that the breaking elongation in a tensile test in the rolling direction is 30.0% or more. If the breaking elongation in the rolling direction is less than 30.0%, the aluminum laminates 1a to 1f will break early when subjected to repeated bending accompanied by flexing, and good electromagnetic wave shielding properties will not be obtained. Therefore, the breaking elongation of the aluminum laminates 1a to 1f is preferably 30.0% or more, more preferably 35.0% or more, and even more preferably 40.0% or more. If the breaking elongation of the aluminum laminates 1a to 1f is within the above range, they will be more resistant to breaking.

[0043] <Width strain ratio in the width direction during roll processing of aluminum laminate> The aluminum laminates 1a to 1f of this embodiment have the characteristic that the width strain ratio r in the rolling width direction is 0.60 or more. The width strain ratio r in the rolling width direction is calculated by the following formula (1), where W0 is the width of the aluminum laminate before tensile deformation, W is the width of the aluminum laminate after tensile deformation, L0 is the length of the aluminum laminate before tensile deformation, and L is the length of the aluminum laminate after tensile deformation, and is an index that represents the anisotropy when tensile deformation is applied to a material. r=log(W0 / W) / log[(W×L) / (W0×L0)]···(1) r: width strain ratio W0 (mm): Width before tensile deformation, W (mm): Width after tensile deformation L0 (mm): Length before tensile deformation, L (mm): Length after tensile deformation

[0044] If the width strain ratio in the roll processing width direction of the aluminum laminates 1a to 1f is less than 0.60, repeated bending will cause many pinholes to appear in the aluminum foil (layer) 2 of the aluminum laminates 1a to 1f early on, making it impossible to obtain good electromagnetic wave shielding properties.

[0045] Although the detailed mechanism behind this is unclear, it is presumed to be as follows: When the aluminum laminates 1a to 1f are repeatedly bent, as described above, they are subjected to alternating tensile and compressive deformation in the rolling direction. That is, the deformation of the aluminum laminates 1a to 1f due to this force is separated into deformation in the thickness direction and deformation in the width direction. However, when the width strain ratio is high, that is, when the aluminum laminates are easily deformed in the width direction, it becomes easier to deform while suppressing the occurrence of pinholes in the aluminum foil (layer) 2, and it is thought that good electromagnetic wave shielding properties can be obtained.

[0046] <Aluminum foil characteristics (diffraction intensity ratio)> In the aluminum laminates 1a to 1f of this embodiment, the aluminum foil 2 has a diffraction intensity I 1 indicating the (200) plane relative to a total diffraction intensity I 0 , which is the sum of the diffraction intensities indicating the (111) plane, the (200) plane, the (220) plane, and the (311) plane, in X-ray diffraction.200 The ratio P 200 is 30% or more and 60% or less, and the diffraction intensity I indicating the (220) plane is 220 The ratio P 220 is preferably 10% or more and 40% or less.

[0047] Diffraction intensity I showing the (200) plane of aluminum foil 2 200 The ratio P 200 and diffraction intensity showing (220) plane I 220 The ratio P 220 By setting the value of the thickness of the laminated body 1a to 1f within the above range, it is possible to impart excellent bending properties to the aluminum laminated bodies 1a to 1f against repeated bending.

[0048] Diffraction intensity indicating the (200) plane in X-ray diffraction I 200 The ratio P 200 is the ratio P of the diffraction intensity of each of the (111), (200), (220), and (311) planes on the diffraction chart measured as an integrated intensity after background (BG) removal, to the total diffraction intensity I0, which is the sum of each of the above diffraction intensities. 200 and is calculated by the following (Equation 2): The actual measurement of the integrated intensity is carried out by reading it using an integrated intensity calculation program, which is the analysis software of the X-ray diffraction device used. P 200 =[{(200) plane diffraction intensity I 200} / {total diffraction intensity of (111), (200), (220), and (311) planes I0} × 100 [%] (Equation 2)

[0049] Diffraction intensity showing the (220) plane in X-ray diffraction I 220 The ratio P 220 can be calculated in the same way. That is, the numerator of (Equation 2) is expressed as the diffraction intensity I 220 The surface on which the X-ray diffraction intensity is measured is the rolled surface of the aluminum foil 2, i.e., the surface that comes into contact with the rolling roll during cold rolling when producing the aluminum foil 2, and is also the surface of the aluminum foil (layer) 2 of each of the aluminum laminates 1a to 1f.

[0050] The present inventors have determined that, in the diffraction intensity detected by X-ray diffraction, the diffraction intensity I representing the (200) plane is smaller than the total diffraction intensity I0. 200 The ratio P 200 is 30% or more and 60% or less, and the diffraction intensity I 220 The ratio P 220 It has been found that by setting the ratio of the diffraction intensity I 200 , I 220 Each ratio P 200 , P 220 If the diffraction intensity is out of the above range, the balance of each crystal orientation is lost, resulting in a deterioration in the bending characteristics against repeated bending. From the viewpoint of the bending characteristics against repeated bending, the ratio of the diffraction intensity I0, which indicates the (200) plane, to the total diffraction intensity I0, which is the sum of each diffraction intensity, is 200 The ratio P 200 It is more preferable that the ratio is 30% or more and 50% or less.

[0051] Diffraction intensity showing (200) and (220) planes I 200 , I 220 Each ratio P 200 , P 220 In order to keep the value within the predetermined range, there are no particular limitations. To homogenize an ingot having the composition of the aluminum foil 2 described below, the homogenization heat treatment temperature can be set to a temperature commonly used in the past (approximately 500 to 540°C) or a higher temperature (e.g., 570 to 630°C). The working conditions for the subsequent plate-making process (hot rolling, cold rolling, intermediate annealing) and the foil-making process (cold rolling) can be set to common conditions. Furthermore, the resulting aluminum foil may or may not be subjected to final annealing. By laminating the aluminum foil 2 thus produced, having a thickness of 5 to 300 μm, with at least one resin film 3, aluminum laminates 1a to 1f exhibiting excellent flexibility against repeated bending can be obtained.

[0052] <Aluminum foil characteristics (thickness)> The thickness of the aluminum foil 2 used in this embodiment is preferably 5 μm or more and 300 μm or less, more preferably 5 μm or more and 150 μm or less, and even more preferably 6 μm or more and 80 μm or less.

[0053] If the thickness of the aluminum foil 2 is less than 5 μm, it may break or pinholes may occur or expand during forming. If the thickness of the aluminum foil 2 exceeds 300 μm, it is difficult to obtain an X-ray diffraction intensity within the range specified in this embodiment, and the weight increases when formed into the aluminum laminates 1a to 1f, resulting in a decrease in the covering ability for cables and the like.

[0054] Therefore, in this embodiment, by controlling the thickness of the aluminum foil 2 within the above-mentioned range, the aluminum laminates 1a to 1f can be easily wrapped around objects with extremely small radii of curvature, such as cables, without causing breakage, and can be formed into electromagnetically shielded cables without impairing flexibility against repeated bending.

[0055] <Aluminum foil characteristics (composition)> The aluminum foil 2 used in this embodiment contains 0.4% by mass or more and 1.7% by mass or less of iron (Fe). The Fe content of the aluminum foil 2 is more preferably 0.7% by mass or more and 1.7% by mass or less, and even more preferably 1.1% by mass or more and 1.7% by mass or less.

[0056] If the Fe content is less than 0.4% by mass, the effect of refining the crystal grains of the aluminum foil 2 becomes insufficient, the strength of the foil decreases, and a relatively large number of pinholes tend to occur after cold rolling. On the other hand, if the Fe content exceeds 1.7% by mass, coarse intermetallic compounds are likely to occur, which reduces workability (rollability, formability) and also makes pinholes more likely to occur.

[0057] Therefore, in this embodiment, the Fe content is controlled to 0.4 mass % or more and 1.7 mass % or less, thereby making the crystal grains of the aluminum foil 2 finer, suppressing the generation of coarse intermetallic compounds, and ensuring appropriate strength and elongation of the aluminum foil 2.

[0058] In the aluminum foil 2 used in this embodiment, the silicon (Si) content is preferably 0.30% by mass or less, more preferably 0.15% by mass or less. If the Si content exceeds 0.30% by mass, coarse crystallized particles are likely to be generated, reducing the effect of refining the crystal grains of the aluminum foil 2 and tending to reduce strength and workability. Note that, since Si is inevitably present in industrial aluminum, the lower limit of the Si content may be set to 0.01% by mass.

[0059] In the aluminum foil 2 used in this embodiment, the copper (Cu) content is preferably 0.05% by mass or less, more preferably 0.02% by mass or less. If the Cu content exceeds 0.05% by mass, the workability and corrosion resistance may be reduced. Note that, since Cu is inevitably present in industrial aluminum, the lower limit of the Cu content may be set to 0.001% by mass.

[0060] In the aluminum foil 2 used in this embodiment, the remainder other than the above-mentioned composition (elements) is aluminum (Al). Here, the aluminum foil 2 may contain trace elements other than the above-mentioned Fe, Si, and Cu in an amount of 0.05 mass% or less. Examples of trace elements include manganese (Mn), magnesium (Mg), zinc (Zn), titanium (Ti), zirconium (Zr), gallium (Ga), chromium (Cr), and vanadium (V). These elements may be present in trace amounts in the aluminum foil 2 as unavoidable impurity elements.

[0061] As described above, the composition of the aluminum foil 2 used in this embodiment has been described, but the composition of the aluminum foil 2 is preferably, for example, a commercially available industrial composition corresponding to alloy number 8021 or 8079 specified in JISH4160-1994. Therefore, the aluminum foil 2 is a versatile aluminum foil having an 8000 series or a composition similar to the 8000 series that does not require expensive additive elements, and has excellent formability and imparts excellent flexibility to the aluminum laminates 1a to 1f against repeated bending when laminated with the resin film 3.

[0062] <Peel strength of aluminum laminate> In the aluminum laminates 1a to 1f of this embodiment, the peel strength between the aluminum foil (layer) 2 and the resin film (layer) 3 is preferably 3.0 N / 15 mm or more when the aluminum laminates 1a to 1f are bent 180° and the aluminum foil (layer) 2 is peeled from the resin film (layer) 3. If the peel strength is less than 3.0 N / 15 mm, the aluminum foil (layer) 2 will not be able to sufficiently follow the deformation of the resin film (layer) 3 when repeatedly bent and deformed, and the aluminum foil (layer) 2 itself may be locally excessively deformed and break.

[0063] <Adhesive (layer)> In the aluminum laminates 1a to 1f of this embodiment, the aluminum foil (layer) 2 and the resin film (layer) 3 may be directly bonded together by, for example, heat fusion, but from the viewpoint of improving peel strength (adhesion strength), the aluminum foil (layer) 2 and the resin film (layer) 3 may be bonded together via a reactive adhesive (layer) 4.

[0064] When laminating the aluminum foil (layer) 2 and the resin film (layer) 3 using the adhesive (layer) 4, it is preferable to use a polyester-based adhesive, a polyester urethane-based adhesive, or the like as the main agent of the adhesive constituting the adhesive (layer) 4, and the coating amount thereof is 0.5 to 10.0 g / m 2 The coating amount is about 0.5g / m 2If it is less than 10.0 g / m, the adhesive strength may be insufficient. 2 Even if the curing agent exceeds this range, no further improvement in adhesive strength is observed, and it is not desirable from the viewpoint of moisture resistance and economy. Furthermore, an aliphatic or aromatic isocyanate can be used as the curing agent.

[0065] In particular, for the aluminum laminates 1a to 1f of this embodiment, it is preferable to use a heat-reactive polyester polyol adhesive consisting of two or more liquids, which has a weight-average molecular weight of 30,000 or more and a softening point after curing of the coating film of 180° C. or more. The bonding method is not particularly limited, but a dry lamination method is preferable.

[0066] <Resin film (layer)> The resin film 3 used in this embodiment is not particularly limited, but preferably contains at least a polyester resin. As the polyester-based resin film, polyethylene terephthalate can be suitably used, but films made of polyethylene naphthalate or polybutylene terephthalate may also be used.

[0067] The resin film 3 may be produced by any known production method, such as inflation, casting, or extrusion. One example is a multilayer film obtained by co-extrusion of a nylon base with a polyester resin or an ethylene vinyl alcohol (EVOH) resin. For the resin film 3 made of polyethylene terephthalate resin, a film produced by general biaxial stretching may be used, or a non-stretched film may also be used. Considering the flexibility and ease of handling of the aluminum laminates 1a to 1f against repeated bending, the thickness of the resin film 3 is preferably, for example, 10 μm to 30 μm, and more preferably 12 μm to 20 μm. Considering the width strain due to compressive stress and tensile stress during bending, the tensile strength ratio (RD / TD) of the resin film 3 is preferably, for example, 1.15 or more, and more preferably 1.2 or more. The resin film 3 may also contain additives or impurities. Examples of additives include curing agents, crosslinking agents, antioxidants, UV absorbers, and lubricants.

[0068] <Printing layer, coating layer> The aluminum laminates 1a to 1f of this embodiment may be further coated or printed from the viewpoint of convenience, decorativeness, etc. Examples of coating layers include an insulating layer, an adhesive layer, a waterproof layer, and a corrosion prevention layer. Known printing inks can be used for the printed layer, and examples of the resin components contained therein include at least one of cellulose, polyvinyl butyral, polyamide, polyolefin, polyurethane, acrylic, polyester, polyvinyl chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, and ethylene-ethyl acrylate copolymer. Examples of coloring components contained in the printing ink include at least one of organic pigments, inorganic pigments, and dyes.

[0069] <Form of use> The aluminum laminates 1a to 1f of this embodiment can be suitably used as an electromagnetic shielding material, particularly as an electromagnetic shielding tape for an electromagnetic shielded cable. They are particularly suitable for use in wiring harnesses that pass through automobile door mirrors, robot arm joints, and other areas that require high flexibility against repeated bending. For example, the aluminum laminates 1a to 1f of this embodiment can be wrapped around a cable to form a cylinder (UO pipe) and then joined to cover the cable. [Example]

[0070] The features of the present invention will be further clarified below by giving examples and comparative examples.

[0071] <Preparation of aluminum foil> First, aluminum foil samples for use in the examples and comparative examples of the present invention were prepared as described below. Aluminum foils A to D shown in Table 1 were prepared and used as aluminum foil samples for the examples and comparative examples. In Table 1, "total of other elements" indicates the total content of inevitable impurity elements (B, Bi, Pb, Na, etc.) other than elements specified by JIS (e.g., JIS H4160).

[0072] [Table 1]

[0073] In the manufacturing process of aluminum foil, an aluminum alloy ingot obtained by DC casting was subjected to homogenization heat treatment in a heating furnace at a predetermined temperature and time. After that, hot rolling was performed, followed by multiple cold rollings, and intermediate annealing was performed at a predetermined temperature and time during the cold rolling. Cold rolling was performed until the thickness of aluminum foil A was 7 μm, aluminum foil B was 7, 12, 15, and 20 μm, aluminum foil C was 7 μm, and aluminum foil D was 7 μm. Furthermore, aluminum foils A, B, and D were subjected to final annealing at a predetermined temperature and time.

[0074] Since the homogenization heat treatment temperature is high, once the temperature of the ingot reaches the homogenization heat treatment temperature, the ingot may be cooled to a temperature at which hot rolling can be started. Furthermore, the homogenization heat treatment time may be within a typical treatment time and is not necessarily limited to the time shown in Table 1. Furthermore, since the intermediate annealing conditions do not significantly affect the properties of the examples and comparative examples of the present invention, the heat treatment temperature and heat treatment time may be within the range of typical operating conditions.

[0075] <Measurement of X-ray diffraction intensity of aluminum foil> For each of the obtained aluminum foil samples A to D, the diffraction intensity I 200 The ratio P 200 and diffraction intensity showing (220) plane I 220 The ratio P 220 X-ray diffraction intensity was measured to calculate the X-ray diffraction intensity. X-ray diffraction intensity was measured using a fully automated multipurpose horizontal X-ray diffractometer (Rigaku Corporation, Smart Lab) and analysis software RINT2000PC (Ver. 3.0.0.0) under the conditions of CuKα radiation, 40 kV, and 30 mA. X-ray diffraction intensities (integrated intensity after background removal) of the (111), (200), (220), and (311) planes were measured by X-ray diffraction. The relative diffraction intensity ratios of the obtained X-ray diffraction intensities of each plane were calculated using the above-mentioned (Equation 1). It was found that the X-ray diffraction intensity of the aluminum foils obtained by measuring aluminum foils A to D alone as described above and aluminum foils A to D in an aluminum laminate gave approximately the same results (measured values).

[0076] <Measurement of aluminum foil composition> The composition of the aluminum foil was measured by measuring 1.00 g of a measurement sample from each of the obtained aluminum foils A to D and analyzing it by inductively coupled plasma optical emission spectrometry (apparatus name: ICPS-8100 manufactured by Shimadzu Corporation).

[0077] <Measurement of the mechanical strength of aluminum foil> The tensile strength, 0.2% yield strength, and breaking elongation of the aluminum foil were measured at room temperature (20°C) using a tensile tester (Toyo Seiki Co., Ltd. Strograph VES5D, strain rate 20 mm / min, sample width 7 mm, chuck distance 100 mm). The 0.2% yield strength was calculated by dividing the cross-sectional area of ​​the sample by the load at which a line with the same slope as the elastic modulus line in the elastic deformation region intersects with the load-displacement curve. The line passes through a point 0.2% of the initial sample length from the elastic modulus intersecting point.

[0078] <Resin film> As the resin films O, P, Q, R, and S to be laminated on the aluminum foil described above, a 12 μm thick nylon resin film O ("ONBC84W#" manufactured by Unitika Ltd.), a 12 μm thick PET (polyethylene terephthalate) resin film P ("PTM" manufactured by Unitika Ltd.), a 12 μm thick PET resin film Q ("ET510" manufactured by Toyobo Co., Ltd.), a 16 μm thick PET resin film R ("T4100" manufactured by Toyobo Co., Ltd.), and a 15 μm thick PBT (polybutylene terephthalate) resin film S ("DE048" manufactured by Toyobo Co., Ltd.) were prepared.

[0079] <Measurement of mechanical strength of resin film> The tensile strength, 0.2% yield strength, and elongation of the above resin films O to S were measured at room temperature (20°C) using a tensile tester (Strograph VES5D, Toyo Seiki Co., Ltd., strain rate 20 mm / min, sample width 7 mm, chuck distance 100 mm). The 0.2% yield strength was calculated by dividing the load at the yield point by the cross-sectional area of ​​the sample. The results are shown in Table 2.

[0080] [Table 2]

[0081] <Production of aluminum laminate> <Production of aluminum laminate> The aluminum foils A to D and resin films O to S were used to prepare aluminum laminates shown in Examples 1 to 4 and Comparative Examples 1 to 10. Specifically, the aluminum foils A to D and resin films O to S were used in the combinations and adhesive application amounts (g / m) shown in Table 3. 2 ), resin films O to S were laminated on one side of aluminum foils A to D using a polyurethane-based dry laminating adhesive to produce aluminum laminates in Examples 2 and 3 and Comparative Examples 2 and 4. In addition, in Examples 1 and 4 and Comparative Examples 1, 3, and 5 to 10, a polyurethane-based dry laminating adhesive (weight after drying: 2.5 g / m 2 ) was used to laminate aluminum foils A to D to prepare aluminum laminates of the examples and comparative examples.

[0082] <0.2% yield strength in the rolling direction of aluminum laminate> The yield strength of the aluminum laminates of Examples 1 to 4 and Comparative Examples 1 to 10 was measured by a tensile test using a Toyo Seiki Strograph VES5D. The aluminum laminates were cut out to a length of 200 mm in the rolling direction (RD) of the aluminum foil in the aluminum laminate and 7 mm in the transverse direction (TD) perpendicular to the rolling direction (RD). The chuck distance was 100 mm, and the tensile speed was 20 mm / min. From the load-displacement curve obtained, the point where a line with the same slope as the elastic modulus line in the elastic deformation region and passing through a point 0.2% of the initial sample length from the elastic modulus intersection point intersected the load-displacement curve was determined as the load at the yield point. The value obtained by dividing this load by the cross-sectional area of ​​the sample was determined as the 0.2% yield strength in the rolling direction.

[0083] <Evaluation of the flexibility of aluminum laminates against repeated bending> The flexibility of the aluminum laminates of Examples 1 to 4 and Comparative Examples 1 to 10 against repeated bending was measured by attaching a bending test jig using a φ150 mm faceplate to a multi-function small tabletop durability testing machine manufactured by Yuasa System Equipment Co., Ltd., and conducting a 90° bending test to the left and right.

[0084] First, an aluminum laminate was cut out to a length of 100 mm in the rolling direction (RD) of the aluminum foil in the aluminum laminate and 7 mm in the width direction (TD) perpendicular to the rolling direction (RD). A cable wire with an outer diameter of 1.6 mm, which had a annealed copper wire conductor and an insulating coating of foamed polyethylene on the outside, was wrapped around the cut-out aluminum laminate lengthwise so that the longitudinal direction of the cable wire coincided with the rolling direction (RD) of the aluminum foil in the aluminum laminate. A copper braided wire with an outer diameter of 2.0 mm was further wound around the outside of the aluminum laminate, which was then placed in a polyolefin resin tube with an outer diameter of 3.6 mm and held at 120°C for 2 minutes to shrink the polyolefin resin tube, thereby producing cables covered with the aluminum laminates of the Examples and Comparative Examples.

[0085] The resulting cable was bent 90° to the left using a mandrel with a bending radius of 5 mm, returned to its original state, and then bent 90° to the right and returned to its original state. This cycle was defined as one cycle (number of times). While the cable was being bent, the electrical resistance at both ends of the aluminum laminate was continuously measured using a digital multimeter GDM-9061 manufactured by Texio Technology Co., Ltd. The number of times (n) the aluminum laminate was bent until the electrical resistance reached 1.0 Ω or greater was determined and used as an index of the aluminum laminate's flexibility against repeated bending. In other words, an increase in the electrical resistance of the aluminum laminate to 1.0 Ω or greater is believed to be due to damage, such as breakage, of all or part of the aluminum foil (layers) in the aluminum laminate. Therefore, the higher the number (n) of bends until breakage or other damage occurred, the better the flexibility against repeated bending. The above bending test was performed three times for each sample, and the average values ​​are shown in Table 3.

[0086] <Measurement of peel strength of aluminum laminate> The peel strength of the aluminum laminate was measured at room temperature (20°C) using a tensile tester (Strograph VES5D, Toyo Seiki Co., Ltd.) with the aluminum foil of the laminate bent 180° and the rest of the laminate not bent, at a peel rate of 200 mm / min, a sample width of 7 mm, and a chuck distance of 100 mm, so that the laminate interface peeled at 180°. Note that the peel strength (N / 15 mm) referred to in this specification is obtained by measuring the peel strength of the above-mentioned strip-shaped sample with a sample width of 7 mm, and converting this value to the peel strength when the sample width is 15 mm (multiplied by 15 / 7).

[0087] <Measurement of mechanical strength of aluminum laminate> The tensile strength, 0.2% yield strength, and elongation at break of the aluminum laminate were measured at room temperature (20°C) using a tensile testing machine (Strograph VES5D, Toyo Seiki Co., Ltd., strain rate 20 mm / min, sample width 7 mm, chuck distance 100 mm). The 0.2% yield strength was calculated by dividing the load at the yield point by the cross-sectional area of ​​the sample. The line, which has the same slope as the elastic modulus line in the elastic deformation region and passes through a point 0.2% of the initial sample length from the elastic modulus intersecting point, intersects with the load-displacement curve.

[0088] <Evaluation of change in resistance value per unit cross-sectional area> Simultaneously with the tensile test, the resistance of the aluminum laminate during the tensile test was measured using a digital multimeter GDM-9061 manufactured by Texio Technology Co., Ltd. using the following method. This is used as an alternative evaluation method for electromagnetic wave shielding properties. When cutting the aluminum laminate to the dimensions described above and conducting the tensile test, both ends of the test piece were bent 10 mm and connected to lead wires to measure the resistance of the aluminum foil on one side of an aluminum laminate measuring 200 mm in length and 7 mm in width. The measured resistance value was calculated as the change in resistance per unit cross-sectional area by dividing the difference up to 30 mm of elongation by the cross-sectional area of ​​the aluminum foil. For aluminum laminates with a breaking elongation of less than 30.0 mm, the resistance was set to infinity (∞) because the laminate had already broken at 30.0 mm of elongation.

[0089] <Evaluation of width strain ratio of aluminum laminate> The width strain ratio of the aluminum laminate was measured by subjecting the aluminum laminate to a tensile test using the tensile tester described above according to the following method. The aluminum laminate was cut into a length of 150 mm in the machine direction (RD) and 7 mm in the transverse direction (TD). The chuck distance was set to 50 mm, and the tensile speed was set to 20 mm / min. The width of the aluminum laminate at an elongation of 20.0% was measured, and the width strain ratio was calculated.

[0090] Table 3 below shows the measurement results of the 0.2% yield strength in the rolling direction, breaking elongation, width strain ratio in the rolling width direction, change in resistance value per unit cross-sectional area, and peel strength of the aluminum laminate. [Table 3]

[0091] <Consideration> Comparing the aluminum laminates of the Examples and Comparative Examples from Table 3, it was found that the aluminum laminates of Examples 1 to 4 achieved an extremely high number of flexing times n of preferably 20,000 times or more, more preferably 25,000 times or more, which cannot be achieved by the aluminum laminates of Comparative Examples 1 to 10, and that they have extremely excellent flexibility against repeated bending. Furthermore, the aluminum laminates of Examples 1 to 4 have a change in electrical resistance per unit cross-sectional area of ​​600 mΩ / mm 2 Since the results are as follows, it is presumed that the aluminum foil (layer) in the aluminum laminate is hardly damaged and retains the high electromagnetic wave shielding properties that are unique to aluminum foil.

[0092] Furthermore, in order to obtain extremely high flexibility against repeated bending while maintaining high electromagnetic wave shielding properties like the aluminum laminates of Examples 1 to 4, at least one resin film (layer) is laminated on the aluminum foil (layer), and the thickness t1 of the aluminum foil (layer) is set to 40% to 60% of the thickness t0 of the aluminum laminate, and the 0.2% yield strength in the rolling direction of the aluminum laminate is set to 50.0 N / mm 2It was found that it is extremely important to make the elongation at break in the rolling direction of the aluminum laminate 30.0% or more and the width strain ratio in the rolling width direction of the aluminum laminate 0.60 or more.

[0093] Furthermore, in order to obtain the above-mentioned properties, as shown in Tables 1 and 3, the aluminum foil used in the aluminum laminate should have a diffraction intensity I0 indicating the (200) plane relative to the total diffraction intensity I0, which is the sum of the diffraction intensities indicating the (111) plane, the (200) plane, the (220) plane, and the (311) plane in X-ray diffraction. 200 The ratio P 200 is 30% or more and 60% or less, and the diffraction intensity I showing the (220) plane relative to the total diffraction intensity I0 220 The ratio P 220 It was found that it is effective to set the content of iron in the aluminum foil to 10% or more and 40% or less, to set the iron content in the aluminum foil to 0.4% by mass or more and 1.7% by mass or less, or to set the thickness of one layer of aluminum foil to 5 μm or more and 300 μm or less.

[0094] Furthermore, as shown in Tables 2 and 3, it is effective for the resin film to contain polyethylene terephthalate resin, and furthermore, it is found that for the aluminum laminate, it is preferable that the peel strength between the resin film (layer) and the aluminum foil (layer) is 3.0 N / 15 mm or more. [Explanation of symbols]

[0095] 1a, 1b, 1c, 1d, 1e, 1f... Aluminum laminate 2. Aluminum foil (layer) 3. Resin film (layer) 4. Adhesive (layer) 5 Printed layer, coating layer

Claims

1. In an aluminum laminate in which at least a resin film and an aluminum foil are laminated, The thickness t of the aluminum foil １ is the thickness of the aluminum laminate, t ０ is 40% or more and 60% or less, The 0.2% yield strength of the aluminum laminate in the rolling direction is 50.0 N / mm ２ is larger than The aluminum laminate has a breaking elongation in the rolling direction of 30.0% or more, and The aluminum laminate has a width distortion ratio in the width direction of roll processing of 0.60 or more. Aluminum laminate for electromagnetic wave shielding tape.

2. The aluminum foil has a total diffraction intensity I, which is the sum of the diffraction intensities of the (111) plane, the (200) plane, the (220) plane, and the (311) plane in X-ray diffraction. ０ Diffraction intensity I showing the (200) plane ２００ The ratio P ２００ is 30% or more and 60% or less, and the total diffraction intensity I ０ Diffraction intensity I showing the (220) plane ２２０ The ratio P ２２０ 2. The aluminum laminate according to claim 1, wherein the ratio of the surface roughness to the surface roughness is 10% or more and 40% or less.

3. The aluminum laminate according to claim 2, wherein the resin film and the aluminum foil are laminated via an adhesive, and the peel strength between the resin film and the aluminum foil is 3.0 N / 15 mm or more.

4. The aluminum laminate according to claim 3, wherein the aluminum foil contains 0.4 mass % or more and 1.7 mass % or less of iron.

5. 5. The aluminum laminate according to claim 4, wherein the thickness of one layer of the aluminum foil is 5 μm or more and 300 μm or less.

6. The aluminum laminate according to claim 5 , wherein the resin film contains at least a polyester-based resin.

7. The aluminum laminate according to claim 6, wherein the resin film contains at least a polyethylene terephthalate-based resin.

8. The aluminum laminate according to any one of claims 1 to 7, further comprising a printed layer or a coating layer laminated thereon.

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