JPWO2011078087A1 - Perforated metal foil - Google Patents

Abstract

An object of the present invention is to provide a perforated metal foil that is thin, can suppress a decrease in tensile strength even when the aperture ratio is increased, and can prevent breakage during handling. In order to solve the above problems, a perforated metal foil having a plurality of oval-shaped through-holes penetrating in the thickness direction, and the three adjacent through-holes have respective center points A, B, and C of the openings. The triangle ABC formed by tying is a substantially equilateral triangle, and forms a triangle ABC arranged so that any one side of the equilateral triangle is parallel to the direction in which the tension is applied to the perforated metal foil, A perforated metal foil characterized in that a plurality of through holes were formed while maintaining the shape of the triangle ABC was employed.

Description

  The present invention relates to a perforated metal foil in which a plurality of through holes are formed in the thickness direction.

  A perforated metal foil in which a plurality of through holes are formed in the thickness direction includes a battery current collector, a catalyst carrier that promotes a chemical reaction, a fine powder classification screen device, a solid-liquid separation screen device, and a microorganism. Nets used for oxygen supply ports of storage containers, dustproof filters for clean rooms, liquid antibacterial filters, liquid reforming filters for imparting metal ions to liquids to modify liquids such as drinking water, electromagnetic shielding, magnetism It is used in a wide range of fields such as industrial materials, conductive materials.

  For example, Patent Document 1 proposes a metal foil in which a large number of through holes are provided in a metal foil in order to prevent an active material from dropping from the metal foil, with respect to a perforated current collector for a secondary battery. Yes. In such secondary batteries, in recent years, there has been a demand for higher density and lighter weight, and accordingly, perforated metal foils for secondary battery current collector applications are thinner and have a higher aperture ratio. Tend to be required. In each of the above applications, it is desired that the range of selection of the thinness and the aperture ratio be widened.

  By the way, when using metal foil as a collector of a secondary battery, an active material is applied to the metal foil. For example, in Patent Document 2, when producing a film electrode for a lithium ion secondary battery, an aluminum foil film or a copper foil film is wound in a roll shape around an unwinding shaft, the film is unwound, and a plurality of support rolls are used. Carrying while supporting, applying an electrode active material paint on one side of the film, performing a process such as drying, and then performing the process of winding in a roll shape with a take-up shaft on both sides of the film, An example in which a film-like electrode in which an electrode active material coating film is formed is manufactured.

Japanese Patent Laid-Open No. 11-67217 JP 2001-113215 A JP-A-11-86869

  Thus, when processing metal foil, there existed a subject that metal foil was easy to fracture | rupture by the winding-up of metal foil, and the tension | tensile_strength of the unwinding direction. In particular, when a perforated metal foil is used as a current collector for a secondary battery, the perforated metal foil having a through hole has a reduced tensile strength and is easily broken during the processing step. That is, a thinner, high aperture ratio perforated metal foil is desired, but on the other hand, it is necessary to prevent breakage of the perforated metal foil during processing, so there is a limit to increasing the aperture ratio thin. .

  With respect to such a problem, in Patent Document 3, by reducing the number of through holes in one row to half or less of the number of columns, a portion where stress is applied is widened, and a reduction in breaking load due to the presence of the through holes is prevented. Therefore, when the active material is applied to the metal foil, or when it is wound up as an electrode plate after the active material is applied, a perforated current collector in which a decrease in breaking load in a direction in which tension is applied is reduced is employed.

  In recent years, perforated metal foils having high through-hole ratio with fine through-holes are desired due to reduction in size, weight and density. That is, in a member such as an electricity storage device, in order to increase the aperture ratio in a metal foil having a limited area, it is necessary to provide a large number of fine through holes to increase the aperture ratio. However, like the perforated current collector described in Patent Document 3, the diameter of the through holes is about 0.1 to 3 mm, and the pitch of the holes, which is the distance between the through holes, is 0.5 to 10 mm. If the number of through-holes in one row is reduced to less than half the number of columns with metal foil, the aperture diameter and aperture ratio corresponding to recent needs cannot be accommodated.

  Therefore, an object of the present invention is to provide a perforated metal foil that is thin and has a high opening ratio, enhances the tensile strength, and can prevent breakage during handling.

  As a result of intensive studies, the present inventors have come to solve the above problems by employing the following perforated metal foil.

  The perforated metal foil according to the present invention is a perforated metal foil having a plurality of oval-shaped through holes penetrating in the thickness direction, and the three adjacent through holes are respectively center points A and B of the openings. , C is a substantially equilateral triangle, and a triangle ABC arranged so that one side of the equilateral triangle is parallel to the direction in which tension is applied to the perforated metal foil. A plurality of through holes are formed while maintaining the shape of the triangle ABC.

  In the perforated metal foil according to the present invention, the breakage resistance in the desired direction of the perforated metal foil is enhanced by devising the arrangement between adjacent through holes and making the shape of the through holes oval. be able to. That is, the perforated metal foil according to the present invention can reinforce the tensile strength in the direction in which tension is applied when the perforated metal foil is used by devising the shape and arrangement of the through holes. As a result, it is possible to provide a perforated metal foil that is thinner and has a higher aperture ratio than the conventional one, can prevent breakage in the processing step for the perforated metal foil, and is excellent in handleability.

It is a schematic diagram which shows the example of arrangement | positioning of the through-hole in the perforated metal foil which concerns on this invention. It is a schematic diagram for demonstrating arrangement | positioning of the through-hole in the perforated metal foil which concerns on this invention. It is a schematic diagram which shows the example of the shape of the through-hole in the perforated metal foil which concerns on this invention. It is a schematic diagram which shows the example of arrangement | positioning of the through-hole in the perforated metal foil which concerns on this invention. It is a schematic diagram which shows the example of arrangement | positioning of the through-hole in the perforated metal foil which concerns on this invention. It is a schematic diagram which shows the example of arrangement | positioning of the through-hole in the perforated metal foil of a comparative example.

  Hereinafter, preferred embodiments of the perforated metal foil according to the present invention will be described. The perforated metal foil according to the present invention is a perforated metal foil having a plurality of through-holes having an oval shape in plan view, and the arrangement and shape of the plurality of through-holes. By devising, the fall of breaking load can be suppressed.

  FIG. 1 is a schematic diagram showing an arrangement example of a plurality of through holes in a perforated metal foil according to the present invention. A plurality of through holes having an oval shape in plan view are formed. The perforated metal foil according to the present invention is characterized by the arrangement of a plurality of through holes, and this will be described using a triangle ABC as shown in FIGS. 1 and 2. As shown in FIGS. 1 and 2, the triangle ABC is a triangle formed by connecting the center points A, B, and C of the openings of the three adjacent through holes 1a, 1b, and 1c. is there. That is, each through-hole 1a, 1b, 1c is formed so as to maintain a constant separation distance and to be centered at a position that is a vertex of a substantially equilateral triangle. Further, the through hole is arranged so that any one side of the triangle ABC is parallel to the direction MD in which the tension is desired to be strengthened in the perforated metal foil.

  Here, when a perforated metal foil is used as a member, tension in a predetermined direction may be required. For example, perforated metal foil is manufactured as a mass-produced product in which a plurality of perforated patterns are repeatedly formed on a long strip-shaped metal foil. The perforated metal foil is further subjected to secondary processing such as surface treatment and cutting in the production line. For example, when a perforated metal foil is used for a current collector of a secondary battery, an active material is applied to the perforated metal foil. And in the manufacturing stage or the secondary processing stage, the perforated metal foil is wound or unwound in a roll shape so that the long band-shaped perforated metal foil is wound or unwound in this roll shape. Tension is easily applied in the direction, and the perforated metal foil is easily broken. In particular, in recent years, perforated metal foils used for applications such as current collectors for secondary batteries tend to require high aperture ratios and thin metal foils, and the tensile strength of metal foils decreases accordingly. Therefore, by arranging the plurality of through holes of the perforated metal foil such that any one side of the above-described triangle ABC is parallel to the direction MD in which the tension is applied to the perforated metal foil, The decrease in the tensile strength of MD was suppressed.

  In the perforated metal foil according to the present invention, the oval-shaped through hole means an oval shape in which the distance between the opening edge end portion and the opening center point is not constant, for example, as shown in FIG. A rounded rectangle such as a rounded rectangle formed by connecting two arcs facing each other in parallel, such as a track of an athletics as shown in FIG. Etc. In addition, it is more preferable that the oval-shaped through-holes have a line-symmetric shape because cracks in the through-holes can be suppressed and a decrease in tensile strength can be prevented.

  Note that the center point of the oval-shaped through-hole is the intersection of the major axis and the minor axis and the middle point between the major axis and the minor axis. Specifically, as shown in FIG. 3A, the center of the through hole in the case of an elliptical shape refers to an intersection P between the major axis r1 and the minor axis r2. In the case of a rounded rectangle, as shown in FIG. 3 (b), it refers to the intersection P between the midpoint of the long diameter r1 with the longest opening distance and the midpoint of the short diameter r2 with the shortest opening distance.

  The central point of the egg-shaped through hole is the intersection of the major axis and the minor axis, and is the midpoint of either the major axis or the minor axis. When the oval through-hole is oval, the long diameter of the through-hole means the longest part of the outer dimensions of the oval through-hole, and the short diameter of the through-hole is perpendicular to the long diameter. The longest part of the outer dimensions in the direction.

  Further, when the perforated metal foil has a long strip shape, the perforated metal foil is arranged so that the direction MD in which the perforated metal foil is wound or unwound in a roll shape and one side of the plurality of triangles ABC are parallel to each other. The

  Further, in the case of a perforated metal foil having an oval-shaped through-hole, as shown in FIGS. 1 and 4, the oval-shaped through-hole has the above-described long diameter and a direction MD in which tension is applied to the perforated metal foil. When the through holes are formed so as to be parallel to each other, it is possible to suppress a decrease in tensile strength in the direction MD of the perforated metal foil even when the aperture ratio is increased.

  In addition, when a through-hole is elliptical shape or a rounded rectangle, it is preferable that the long diameter of the said through-hole is 1.05 times-3 times the short diameter. When the long diameter of the through hole is less than 1.05 times the short diameter, the through hole becomes close to a perfect circle, and the effect of enhancing the tensile strength in a desired direction is hardly obtained. Moreover, when the major axis of the through hole is longer than three times the minor axis, the tensile strength against the tension in the minor axis direction is lowered. The long diameter of the through hole is more preferably 1.1 to 2.5 times the short diameter, and most preferably 1.2 to 2 times the short diameter.

  In the case of a perforated metal foil according to the present invention, in the case of an oval perforated metal foil, in order to ensure sufficient formation accuracy of the through holes and to reduce the opening pitch to ensure a predetermined aperture ratio, More preferably, the diameter is 10 μm to 300 μm. The opening pitch said here means the separation distance between the centers of adjacent through-holes. In order to ensure sufficient formation accuracy of the through hole, 10 μm or more is preferable. On the other hand, in order to ensure a constant aperture ratio with a narrow aperture pitch, the aperture diameter of the through holes is preferably 300 μm or less. The long diameter of the through hole is more preferably 50 μm to 150 μm.

  The opening diameter and pitch of the oval-shaped through holes are set according to the opening ratio, and the size of the triangle ABC is also determined. In addition, if the distance between the opening edge ends of the through holes is too small, the tensile strength is reduced. Therefore, the minimum value of the pitch of the through holes (the length of one side of the triangle ABC) is determined by the opening diameter.

  In the perforated metal foil according to the present invention, the triangle ABC formed by connecting the centers of the three adjacent through holes is a substantially equilateral triangle, and the desired direction MD and one side of the triangle ABC are parallel to each other. By arranging the oval-shaped through hole, the tensile strength in a desired direction can be enhanced. Therefore, it is possible to sufficiently reduce the separation distance between the opening edge ends of the adjacent through holes with respect to the opening pitch. For example, the perforated current collector described in Patent Document 3 has a configuration in which, in one row direction, a portion where no through hole is present is ensured and a portion where stress is applied is widened. As a result, in the perforated current collector described in Patent Document 3, the through-holes in the column between the through-holes adjacent in the row direction cannot be arranged. However, in the perforated metal foil according to the present invention, the through hole 1b and the through hole 1c which are adjacent to each other in the width direction can exist at the position indicated by the line XX in FIG. Therefore, a large number of through holes can be arranged in a limited area, and the aperture ratio can be increased.

  1 shows an example in which all three adjacent through-holes are formed at equal intervals at positions where the relation of the triangle ABC is established, the perforated metal foil according to the present invention is limited to this. It is not something. For example, as shown in FIG. 5, three through-holes satisfying the relationship of a triangle ABC positioned so that any one side is parallel to the direction MD in which tension is applied to the perforated metal foil are spaced apart. A plurality of them may be arranged.

  The perforated metal foil according to the present invention is obtained by forming a plurality of through holes in a metal foil formed of, for example, copper, copper alloy, nickel, nickel alloy, silver, silver alloy or the like.

  The perforated metal foil according to the present invention preferably has an opening ratio per unit area of 20% to 65%. The aperture ratio per unit area is a value obtained by comparing and converting the weight per unit area of the perforated metal foil with reference to the metal foil having the same thickness. When the aperture ratio per unit area is less than 20%, the feature of the present invention that increases the tensile strength while increasing the aperture ratio by forming a plurality of through holes as in the present invention cannot be utilized. On the other hand, when the aperture ratio per unit area exceeds 65%, it becomes difficult to ensure the tensile strength that can withstand the tension in winding or unwinding with a roll. A more preferable aperture ratio is 30% to 60%.

  The perforated metal foil according to the present invention can be particularly suitably used for a thickness of 1 μm to 40 μm. If the thickness of the perforated metal foil is less than 1 μm, the tensile strength is insufficient, the stability of the hole shape and the handleability are lowered, and in particular, the tensile strength that can withstand the tension in winding or unwinding with a roll is secured. It becomes difficult. Further, when the thickness of the perforated metal foil becomes thinner than 7 μm, it becomes difficult to handle with the metal foil alone, but it is possible to use a base material or a support such as a slightly adhesive PET sheet. On the other hand, if the thickness of the perforated metal foil exceeds 30 μm, the advantage of using the perforated metal foil cannot be obtained in terms of reduction in size and weight and manufacturing cost. A more preferable thickness is 5 μm to 25 μm.

  The perforated metal foil according to the present invention can be manufactured by punching, laser drilling, printing method, etching, liquid resist method, plating, dry thin film forming method, etc., and the material, thickness, fineness of the perforated metal foil to be manufactured What is necessary is just to select suitably according to conditions, such as a magnitude | size and a shape of a through-hole.

  Hereinafter, a method of forming a pattern of a through-hole pattern using a resist method and then plating will be exemplified.

  First, a mold is formed on the substrate surface. The base material is preferably a copper foil, a stainless steel foil or the like in terms of handleability. Moreover, you may use a resin provided with a conductive resin or a conductive layer for a base material. The mold has a thickness and is made of a plurality of convex resists corresponding to the shape of the through-holes of the perforated metal foil to be produced. Forming methods of this form include resist printing using relief printing methods such as flexographic printing, intaglio printing methods such as gravure printing, stencil printing methods such as screen printing methods, lithographic printing methods such as offset printing methods and photolithography methods. A method of forming the film by applying it to a substrate, followed by drying and curing can be considered. Among these mold forming methods, one of the above printing methods is preferable in terms of production cost, and the photolithography method is preferable in terms of forming accuracy of the mold.

  In addition, when forming the convex resist used as a mold by a printing method, according to the shape and size of the through-hole to be formed, the substrate surface is covered, and abnormal precipitation occurs during the metal plating step. It is preferable that the thickness is a minimum necessary thickness that does not occur and the outer peripheral edge is inclined. The reason for this is that the physical peelability between the metal plating layer formed after metal plating and the formwork is good and the productivity is excellent, and the surface shape of the opening edge of the through-hole formed is smooth, This is because cracks in the through holes are less likely to occur. On the other hand, a method for forming a convex resist to be a mold by a photolithography method will be described. First, after laminating a commercially available DFR (dry film resist) on a base material, a pattern corresponding to the shape and size of a through hole to be formed is formed, and unnecessary portions are removed to form a convex resist. Next, after metal plating and removing the remaining convex resist pattern, the metal plating layer and the substrate are physically peeled off. In the case of the photolithography method, after removing the commercially available DFR, the metal plating layer can be physically peeled off.

Next, in a state where the mold is formed on the surface of the base material, a metal plating layer is electrodeposited on a portion other than the convex resist that becomes the mold by an electrolytic plating method. After that, by removing the base material and the formwork, a perforated metal foil with a smooth shape with rounded opening edges of the through-holes was obtained, and when the tension was applied to the perforated metal foil It is possible to suppress the occurrence of cracks at the edge of the opening edge. When forming a perforated metal foil by an electrolytic plating method, a known electrolytic plating method capable of enhancing the tensile strength, such as adjusting the plating conditions such as current density and plating solution, may be applied. For example, when using a copper sulfate-based plating bath, the current density during electrolytic plating is preferably in the range of 20 A / dm ^{2 to} 100 A / dm ² . When the current density is lower than 20 A / dm ² , the productivity is lowered. On the other hand, if the current density is higher than 100 A / dm ² , the composition of the plating solution tends to fluctuate due to heat generation, and it becomes difficult to form a high-quality metal plating layer.

  When forming through-holes by machining such as punching, burrs are likely to occur in the through-holes, which may lead to breakage of the perforated metal foil, affecting the product's accuracy with respect to design tensile strength. In addition, a perforated metal foil with a small-diameter through-hole is not suitable because adjustment becomes difficult.

  As described above, the perforated metal foil according to the present invention prevents a decrease in tensile strength in a desired direction while adjusting the formation position of the through hole while maintaining a high aperture ratio. That is, in the present invention, in the perforated metal foil, the tensile strength is set to a minimum level necessary for practical use in a direction in which the tension is not so much a problem, while the tensile strength is mainly applied in a direction in which the tension is easily applied. Strength is strengthened. As a result, even if the perforated metal foil according to the present invention is a perforated metal foil having a high aperture ratio, it is possible to prevent damage due to a physical load during processing. Examples of perforated metal foil according to the present invention will be described below.

  Example 1 is an example of a perforated metal foil provided with an elliptical through hole in a copper foil having a thickness of 9.4 μm. That is, when connecting the center points ABC of adjacent through holes, each side has a regular triangle with a length of 245 μm. As schematically shown in FIG. 1, the long diameter of each through hole and the perforated metal foil A perforated metal foil having an aperture ratio of 24% and having an elliptical through hole having a major axis of 170 μm and a minor axis of 95 μm at a position substantially parallel to the length direction MD was obtained. Here, the aperture ratio is a value obtained by comparatively converting the weight per unit area with reference to a copper foil having a thickness of 10 μm.

  The perforated metal foil of Example 1 was produced by the following method. First, by using a lithographic screen printing method, a resist ink (thermosetting ink for screen printing manufactured by Toyo Ink Co., Ltd.) is applied to the surface of a base material (copper foil having a thickness of 35 μm), and a pattern of through holes to be produced A plurality of convex resists corresponding to the above were formed. The convex resist has an elliptical shape in plan view, and is formed so that the thickness gradually decreases toward the outer peripheral edge. And the resist ink after printing was heat-dried and hardened.

  Next, the base material on which the resist pattern is formed is immersed in an aqueous solution containing carboxybenzotriazole at a concentration of 3 g / l. A release layer was formed.

  Copper plating was performed on the surface of the base material on which the resist pattern was formed, and a copper plating layer having a thickness of 10 μm was formed at the location where the organic release layer was formed to form a perforated metal foil with a base material. And the copper plating layer was formed not only on the organic peeling layer but also on the outer peripheral edge of the convex resist.

The copper plating conditions at this time were such that the bath composition was a copper sulfate pentahydrate concentration of 250 g / L, sulfuric acid of 80 g / L, a bath temperature of 45 ° C., and a current density of 20 A / dm ² .

  Next, the perforated metal layer was physically peeled from the substrate, and the substrate was removed together with the resist pattern to obtain a perforated metal foil.

  The tensile strength and elongation of the perforated metal foil obtained in Example 1 were measured to evaluate physical properties. Tensile strength was measured in the length direction MD and the width direction TD for a perforated metal foil having a width of 10 mm and a length of 100 mm in accordance with a tensile test (JIS C6511-1992). Here, the length direction MD is a direction in which tension is applied in the usage pattern of the perforated metal foil, and the width direction TD is a direction perpendicular (orthogonal) to the length direction MD. In addition, the elongation is measured by fixing the distance of the gripping tool with the perforated metal foil to 50 mm as an initial distance, and measuring the displacement of the gripping tool at the time of breakage. Calculation was performed using Equation 1.

  As a result, the perforated metal foil of Example 1 had a tensile strength per 10 mm of 27.0 N and an elongation rate of 1.7% in the longitudinal direction MD. On the other hand, in the width direction TD, the tensile strength per 10 mm was 14.5 N and the elongation rate was 0.9%. The results of Example 1 are shown in Table 1. From this result, it can be said that the perforated metal foil of Example 1 is strengthened in the MD direction more than the TD direction in both tensile strength and elongation.

  Example 2 is an example of a perforated metal foil provided with a through hole having a rounded rectangular shape on a copper foil having a thickness of 9.4 μm, as schematically shown in FIG. The through hole had a rounded rectangular shape with a major axis r1 = 175 μm, a minor axis, and the diameters of arcs at both ends were r2 = 115 μm. Then, when connecting the center points ABC of the adjacent through holes, each side has a regular triangle with a length of 245 μm. As shown in FIG. 4, the long diameter of each through hole and the length direction of the perforated metal foil A perforated metal foil having a through-hole of 30% provided with a through hole at a position where MD is substantially parallel was produced in the same manner as in Example 1.

  The tensile strength and elongation of the perforated metal foil of Example 2 were measured in the same manner as in Example 1. The results of Example 2 are shown in Table 1. From this result, it can be said that the perforated metal foil of Example 2 is strengthened in the MD direction more than the TD direction in both tensile strength and elongation.

The perforated metal foil of Example 3 has the same shape as the perforated metal foil of Example 1, and is an example in which the current density during production is different. That is, in this example, a perforated metal foil having the same shape was produced under the same conditions as in Example 2 except that the current density during electrolytic plating was 27 A / dm ² .

  The tensile strength and elongation of the perforated metal foil of Example 3 were measured in the same manner as in Example 1. The results of Example 3 are shown in Table 1. From this result, it can be said that the perforated metal foil of Example 3 is strengthened in the MD direction more than the TD direction in both tensile strength and elongation. In addition, the tensile strength was improved as compared with Example 1.

The perforated metal foil of Example 4 has the same shape as the perforated metal foil of Example 2, and is an example in which the current density during production is different. That is, in this example, a perforated metal foil having the same shape was produced under the same conditions as in Example 2 except that the current density during electrolytic plating was 31 A / dm ² .

  The tensile strength and elongation of the perforated metal foil of Example 4 were measured in the same manner as in Example 1. The results of Example 4 are shown in Table 1. From this result, it can be said that the perforated metal foil of Example 4 is strengthened in the MD direction more than the TD direction in both tensile strength and elongation. In addition, the tensile strength was higher than that of the perforated metal foil of Example 2.

  The perforated metal foil of Example 5 was a perforated metal foil having an elliptical through hole in a copper foil having a thickness of 10.1 μm and an aperture ratio of 39%. In the perforated metal foil of Example 5, when connecting between the center points ABC of adjacent through holes, each side has a regular triangle of 151 μm in length. A plurality of elliptical through holes having a major axis of 108 μm and a minor axis of 96 μm were formed at positions where the length direction MD of the perforated metal foil was substantially parallel. That is, as compared with Examples 1 and 3, a perforated metal foil in which a large number of through holes having a small opening area and a long diameter / short diameter ratio were formed to increase the opening ratio was obtained. However, a UV ink for screen printing manufactured by Toyo Ink Co., Ltd. was used as a resist ink for forming a convex resist on the substrate surface. Other manufacturing conditions were the same as those in Example 1.

The tensile strength and elongation of the perforated metal foil of Example 5 were measured in the same manner as in Example 1. The results of Example 5 are shown in Table 1. From this result, it can be said that the perforated metal foil of Example 5 is stronger in the MD direction than in the TD direction in both tensile strength and elongation even when the ratio of the major axis to the minor axis is small. In particular, it can be said that the tensile strength in the MD direction shows a high value as a perforated metal foil having an aperture ratio of 39% with a copper foil having a thickness of 10 μm.
[Comparative example]

  The comparative example is a copper foil having a thickness of 9.8 μm, and an example of a perforated metal foil having a 25% aperture ratio in which circular through holes are uniformly distributed and arranged in a pattern as schematically shown in FIG. Indicates. The through-holes of the perforated metal foil are circular with a diameter of 128 μm, the distance between the center points ABC of the adjacent through-holes is set to a pitch of 245 μm, and the distance between the opening edge ends of each through-hole is 117 μm. did. This perforated metal foil was produced in the same manner as in Example 1.

Comparison between Examples and Comparative Examples: All of the perforated metal foils of Examples 1 to 5 showed sufficient values for the tensile strength in the longitudinal direction MD to which tension was applied. In addition, the elongation rate was a value that could withstand practical use. On the other hand, it can be seen that the perforated metal foil shown in the comparative example has a lower tensile strength in the MD direction than Examples 1 to 5 in view of the aperture ratio. Therefore, when the perforated metal foil of the form shown in Examples 1 to 5 is a band-shaped perforated metal foil that is long in the length direction MD, it depends on the roll at the time of manufacturing and secondary processing. It can be said that it has a physical strength that can sufficiently withstand the tension applied to the perforated metal foil during winding or unwinding. Furthermore, although the perforated metal foils of Examples 1 and 2 have the same or higher aperture ratio than the perforated metal foils of the comparative examples, the tensile strength in the MD direction is equal to or higher than that of the comparative examples. I was able to. From this result, it can be seen that when the oval-shaped through-hole is employed in the perforated metal foil, the fracture resistance in a specific direction (MD) can be enhanced. In addition, it can be said that even if the aperture ratio is increased, a decrease in fracture resistance can be suppressed.

  Since the perforated metal foil according to the present invention can enhance the tensile strength in a desired direction, it is possible to provide a perforated metal foil excellent in physical strength while maintaining the tensile strength while increasing the aperture ratio. Such a perforated metal foil having a high opening ratio with excellent physical strength is excellent in handling properties as a member, so a current collector such as a lithium ion secondary battery, a magnetic material, a conductive material, and a wide range of other It can be suitably used in various fields. In addition, perforated metal foil with high opening ratio with excellent physical strength is excellent in fracture resistance even after being attached to the final product as a member, so for example, liquid modification for modifying liquids such as drinking water It can be used as a member that can be used for a long period of time, such as filter use.

1a, 1b, 1c ... through hole A, B, C, P ... center point of through hole

Claims (5)

A perforated metal foil having a plurality of oval-shaped through holes penetrating in the thickness direction,
Three adjacent through-holes are triangles ABC formed by connecting the center points A, B, and C of the respective openings, and are substantially equilateral triangles. With respect to the direction in which tension is applied to the perforated metal foil, Forming a triangle ABC arranged such that any one side of the equilateral triangle is parallel;
A perforated metal foil, wherein a plurality of through holes are formed in a state where the shape of the triangle ABC is maintained. Perforated metal foil is a long strip,
2. The perforated metal foil according to claim 1, wherein the perforated metal foil is disposed so that a direction in which the perforated metal foil is wound or unwound in a roll shape is parallel to one side of the plurality of triangles ABC. The oval through-hole is elliptical, rounded rectangular or oval, and the through-hole is formed so that the long diameter of the through-hole is parallel to the direction in which tension is applied to the perforated metal foil. The perforated metal foil according to claim 1 or 2. 4. The perforated metal foil according to claim 3, wherein a major axis of the oval-shaped through hole having an elliptical shape or a rounded rectangular shape is 1.05 to 3 times the minor axis. The perforated metal foil according to any one of claims 1 to 4, wherein the aperture ratio per unit area is 20% to 65%.

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