JP6978262B2 - Breathable waterproof metal leaf - Google Patents

Description

The present invention relates to a metal foil having both breathability and waterproofness.

Applications of metal foils are expanding as conductive materials and electromagnetic wave shielding materials, and thin and light porous metal foils having light transmission and gas transmission as new functions are required. In particular, a porous copper foil in which fine holes are provided in a copper foil to impart transparency is expected to be used in various fields as a filter material having conductivity. While thinner and lighter porous metal foils are required, it is also required to control the size of fine pores and improve the uniformity of fine pores. Further, there is an increasing demand for metal foils having so-called breathability and waterproofness, in which gas is permeated but liquid is not permeated.

As a method for producing a metal foil having fine pores, various methods have been conventionally provided as disclosed in Patent Documents 1 to 5. Of these, there are those in which holes are made in the metal leaf mainly using a mold or laser, or holes are made by methods such as punching and etching, but fine and uniform holes are formed in the thin metal leaf. It was difficult to do. For example, processing is not possible unless the thickness of the metal foil is about 20 to 100 μm, and the hole diameter is limited to a relatively large size such as 100 μm or more.

Therefore, the porous metal leaf obtained by the conventional method cannot exhibit uniform permeability when the size and weight are reduced. A field in which a thinner metal foil in which smaller size pores are uniformly distributed so that the permeability of gas and liquid components is not biased is desired, for example, lithium ion. In the fields of negative electrode plates for negative electrodes such as batteries, sheet-shaped electrode plates, various filters, and electromagnetic wave shielding materials for flexible circuit boards, there is a strong demand for porous metal foils with sufficiently satisfactory performance and methods for manufacturing them. There is.

In addition, the porous metal leaf formed by the conventional method has a pore diameter of 100 μm or more, which is too large, so that it is not possible to prevent the permeation of the liquid. There is a need for a metal foil that can be used in fields where breathability and waterproofness are required, for example, a positive electrode current collector for an air magnesium battery and a heat dissipation filter for an AC adapter.

Japanese Unexamined Patent Publication No. 2007-169766 Japanese Unexamined Patent Publication No. 2007-277641 Japanese Unexamined Patent Publication No. 2009-249643 Japanese Unexamined Patent Publication No. 2012-026019 Japanese Unexamined Patent Publication No. 2013-227637

An object of the present invention is to provide a metal foil that allows gas to permeate and does not allow liquid to permeate, that is, a breathable waterproof metal foil. That is, a metal foil having both breathability and waterproofness is provided.

As a result of diligent research, the present inventors obtain a metal foil having both breathability and waterproofness by laminating a liquid-repellent film on the surface of a metal foil having a predetermined pore diameter and pore density. We found that we could complete the present invention.

The breathable waterproof metal leaf of the present invention has a metal leaf in which fine holes having a hole diameter of 30 μm or less are formed at a pore density of ^{100 pieces / mm 2} or less, and 1- [ N, N-bis (2-ethylhexyl) aminomethyl) benzotriazole or 1- [N, N-bis (2-ethylhexyl) aminomethyl] methylbenzotriazole as the main component has a water contact angle of 70 ° or more. It is a breathable waterproof metal leaf, characterized in that a water-repellent film is laminated and the air permeability is 38 sec / 100 mL or more and 1200 sec / 100 mL or less.

The water pressure resistance of the breathable waterproof metal leaf ^{is preferably 50 gf / cm 2} or more.

According to the present invention, a breathable waterproof metal leaf having both breathability and waterproofness can be obtained. Since the obtained breathable waterproof metal leaf has a predetermined micropore structure, it also has waterproofness while satisfying desired breathability. Needless to say, since it is a metal foil, it also has conductivity and electromagnetic wave shielding properties.

The breathable waterproof metal leaf according to the present invention is excellent in usability because it can be easily peeled off from the support when necessary. In one example, the breathable waterproof metal leaf can be peeled off from the support and used alone. In another example, a usage method is also adopted in which the support is attached to a desired object with the support attached, and then only the support is peeled off. In this case, it becomes easy to prevent the occurrence of wrinkles when the breathable waterproof metal foil is attached to the object. Examples of the object include articles made of resin, glass, ceramics and the like.

It is a magnified transmitted light image of the breathable waterproof metal leaf of the present invention.

The breathable waterproof metal foil of the present invention is based on a metal leaf in which fine pores having a pore diameter of 30 μm or less are formed at a pore density of ^{100 pieces / mm 2 or less.} When the pore diameter exceeds 30 μm or the pore density is ^{more than 100 pieces / mm 2} , waterproofness cannot be exhibited even if the air permeability is sufficient. When the hole diameter is 30 μm or less, 0 μm is numerically included, but it is excluded because there is no hole with 0 μm. Similarly, when the pore density is 100 pieces / mm ² or less, 0 pieces / mm ² is also included in the numerical range, but the hole density of 0 pieces / mm ² means that there are no holes, and of course. It is excluded from the breathable waterproof metal leaf of the present invention because it cannot be breathable.

The breathable waterproof metal leaf of the present invention has a water contact angle of 70 ° or more on at least one surface of the metal leaf in which fine holes having a hole diameter of 30 μm or less are ^{formed at a hole density of 100 pieces / mm 2 or less.} A water-repellent film is laminated. The water-repellent film preferably has a rust preventive effect at the same time. The main components of the film having water repellency and rust preventive effect are 1- [N, N-bis (2-ethylhexyl) aminomethyl) benzotriazole or 1- [N, N-bis (2-ethylhexyl) aminomethyl). ] Methylbenzotriazole and the like can be mentioned.

The breathable waterproof metal leaf of the present invention preferably has a breathability of 1200 sec / 100 mL or less. The air permeability in the present invention is a measured value obtained by the following test method. Breathable waterproof metal leaf is set in a Garley type densometer (JIS-L1096 compliant) and the air permeability is measured. As a condition of this time, the inner cylinder weight 567 g, aeration circular area 642 mm ^2, a vent circle diameter 28.6 mm ^2, which measures the time air 100mL passes. The unit of air permeability is sec / 100 mL.

The breathable waterproof metal leaf of the present invention preferably has a water pressure resistance of 50 gf / cm ² or more. The water pressure resistance in the present invention refers to a measured value obtained by the following test method. A transparent PVC pipe with an inner diameter of 20 mm and a length of 2000 mm is erected vertically, and the bottom of the PVC pipe is covered. A circular hole with a diameter of 5 mm is made on the side surface of the PVC pipe near the lower bottom, and the hole is closed with a breathable waterproof metal leaf. Water is gradually filled from the upper end side of the PVC pipe, and when water droplets leak from the micropores of the breathable waterproof metal leaf, the filling of water is stopped. The distance from the center of the hole having a diameter of 5 mm on the side surface of the PVC pipe to the water surface was measured, and the water pressure applied to the breathable waterproof metal leaf was taken as the water pressure resistance. For example, when the distance from the center of the hole to the water surface is 50 cm, the water pressure resistance is 50 gf / cm ² .

An example of the method for producing the breathable waterproof metal leaf of the present invention is shown. First, as a support for the breathable waterproof metal leaf, a base material having aluminum on at least a part of the surface is used. Specific examples thereof include a synthetic resin film having a metal layer made of aluminum formed on the surface thereof, an aluminum foil, an aluminum plate, and the like. From the viewpoint of workability in the plating treatment step described later, it is preferable that a resin film as a reinforcing material is bonded to one surface of the aluminum foil. The resin film as a reinforcing material preferably has resistance to chemicals in the plating treatment step. For example, polyester, polyimide, polypropylene and the like can be mentioned.

The alkaline treatment step of bringing the alkaline aqueous solution into contact with the aluminum surface of the support is first carried out. Examples of the alkaline aqueous solution include a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution. The concentration of the alkaline aqueous solution is preferably 0.4 to 8.0% by mass in the case of a sodium hydroxide aqueous solution, for example. The temperature of the alkaline aqueous solution to be brought into contact with the aluminum surface is preferably 15 to 45 ° C., and the contact time is preferably 30 to 600 seconds.

In the atmosphere, the surface of aluminum is oxidized and passivated. It is considered that the alkali treatment step has the effect of dissolving a part of this passivation and exposing a part of unoxidized aluminum. On the passivated aluminum surface, metal precipitation cannot be expected even if electroplating is performed in the subsequent plating process.

After performing the alkaline treatment, the plating step, which is the next step, is immediately carried out. As described above, a part of the passivation is removed by the alkali treatment step, but if it is left for a long time, air oxidation proceeds and it becomes passivation again. The time interval between the alkali treatment step and the plating step is preferably 180 seconds or less.

In the plating process, an electrolytic copper plating process or an electrolytic nickel plating process is performed. As the composition of the copper plating solution or the nickel plating solution, a conventionally known formulation can be used, or a commercially available electrolytic copper plating solution can be used.

As a condition in the electrolytic copper plating treatment, the current density is preferably in the range of ^{2 to 3 A / dm 2.} When the current density of the electrolytic copper plating treatment is within this range, precipitation of metallic copper, which is the core of the peelable porous copper foil, is achieved on the aluminum surface of the support from which the passivation has been removed. If the current density of the electrolytic copper plating process ^{is less than 2 A / dm 2} , the adhesion between the aluminum support and the porous copper foil becomes too strong, and the peelability may be lost. On the other hand, if the current density of the electrolytic copper plating process ^{exceeds 3 A / dm 2} , there is a possibility that a sufficient number of micropores may not be formed.

The treatment temperature of the electrolytic copper plating treatment is preferably 30 to 60 ° C., and the treatment time is preferably 60 to 2400 seconds. After the plating treatment, washing with water and drying may be carried out if necessary.

As a condition for the nickel plating treatment, the current density is preferably in the range of ^{1.5 to 2 A / dm 2.} When the current density is within this range, precipitation of metallic nickel, which is the core of the peelable porous nickel foil, is achieved on the aluminum surface of the support from which the passivation has been removed. If the current density is ^{less than 1.5 A / dm 2} , the adhesion between the aluminum surface of the support and the porous metal leaf becomes too strong, and the peelability may be lost. On the other hand, if the current density ^{exceeds 2 A / dm 2} , the limit current density may be exceeded and burns and burns may occur.

The treatment temperature of the electrolytic nickel plating treatment is preferably 30 to 60 ° C., and the treatment time is preferably 60 to 2400 seconds. After the plating treatment, washing with water and drying may be carried out if necessary.

The electrolytic copper plating treatment and the nickel nickel plating treatment can be carried out in two or more stages. In this case, the first-stage treatment may be carried out under the above-mentioned treatment conditions, and the current density may be carried out in the range of ^{0.5 to 3.5 A / dm 2 as the second-stage plating treatment conditions.} In this way, the diameter and density of the holes in the metal leaf can be controlled by controlling the processing conditions in the electrolytic copper plating process and the electrolytic nickel plating process, particularly the current density.

In the metal foil obtained by the plating step, the diameter of the pores is 30 μm or less. Further, the density of the holes is 100 pieces / mm ² or less. If the diameter and density of the holes are within this range, both breathability and waterproofness can be achieved. The thickness of the breathable waterproof metal leaf is preferably 1 to 12 μm. If the thickness is in this range, the flexibility peculiar to metal leaf can be obtained. After the plating step, it can be washed with water and dried as needed.

Next, a water-repellent film is laminated on at least one surface of the metal foil obtained by the above step. As a method for laminating the water-repellent film, 1- [N, N-bis (2-ethylhexyl) aminomethyl] benzotriazole, 1- [N, N-bis (2-ethylhexyl) aminomethyl] methylbenzotriazole, etc. are used. It is preferably a dipping treatment in the contained aqueous solution. The treatment temperature is preferably 20 to 60 ° C., and the treatment time is preferably 30 to 300 seconds. In the case of the dipping treatment, a water-repellent film is also formed on the surface of the metal foil on the support side. This is probably because the treatment liquid passes through the micropores of the metal foil and penetrates to the boundary between the metal foil and the aluminum surface of the support. Other methods for laminating the water-repellent film include a spray method and a coating method.

The present invention will be described below by way of examples, but the present invention is not limited by these examples. The methods for measuring various physical properties are as follows.

(1) Measurement of hole density Light was irradiated from the back side of the breathable waterproof metal leaf, and the transmitted light image was photographed with a microscope (KEYENCE DIGITAL MICROSCOPE VHX-5000, manufactured by KEYENCE CORPORATION). The number of dots of the transmitted light image existing in the square region of 1.26 mm per piece was counted, and the density of the holes was calculated.

(2) Measurement of hole diameter The diameter of all dots of the transmitted light image existing in a square of 1.26 mm was measured with a microscope (KEYENCE DIGITAL MICROSCOPE VHX-5000), and the average value was taken as the hole diameter. ..

[Example 1]
As the support, an aluminum foil (8021, thickness 20 μm, manufactured by UACJ Corporation) and a polyester resin film (thickness 75 μm, manufactured by Futamura Chemical Co., Ltd.) bonded by dry laminating was used. A 4% by mass sodium hydroxide aqueous solution was used as the alkaline aqueous solution, and the aluminum support was contacted by a dipping method at 42 ° C. for 25 seconds and at 30 ° C. for 25 seconds.

Next, the first-stage electrolytic copper was prepared with an electrolytic copper plating solution prepared to 200 g / L of copper sulfate pentahydrate, 55 mL of sulfuric acid, 85 mg / L of sodium chloride, and 5 g / L of polyethylene glycol # 4000 (manufactured by Kanto Chemical Co., Inc.). A plating process was carried out. The current density was 2.5 A / dm ² , and the processing time was 444 seconds. The treatment temperature was 40 ° C.

Next, the second stage electrolytic copper was prepared with an electrolytic copper plating solution prepared to 200 g / L of copper sulfate pentahydrate, 55 mL of sulfuric acid, 85 mg / L of sodium chloride, and 5 g / L of polyethylene glycol # 4000 (manufactured by Kanto Chemical Co., Inc.). A plating process was carried out. The current density was 0.5 A / dm ² , and the processing time was 1440 seconds. The treatment temperature was 40 ° C.

After that, it was immersed in a 100 mL / L aqueous solution of VERZONE SF-310 (manufactured by Yamato Kasei Co., Ltd., modified benzotriazole type) at 40 ° C. for 180 seconds to perform rust prevention treatment, and a breathable waterproof metal leaf with a support was obtained. rice field. The obtained breathable waterproof metal leaf has a thickness of 10.2 μm, an aperture ratio of 0.32%, a hole diameter of 9 μm, a hole density of 36 pieces / mm ² , a breathability of 38 seconds / 100 mL, and a water pressure resistance. It was 65 gf / cm ^2. The results are shown in Table 1.

[Example 2]
A breathable waterproof metal leaf with a support was obtained in the same manner as in Example 1 except that the current density in the second-stage electrolytic copper plating treatment was 1.0 A / dm ^{2 and the treatment time was 720 seconds.} Table 1 shows the thickness, aperture ratio, hole diameter, hole density, air permeability, and water pressure resistance of the obtained breathable waterproof metal leaf.

[Example 3]
A breathable waterproof metal leaf with a support was obtained in the same manner as in Example 1 except that the current density in the second-stage electrolytic copper plating treatment was 2.0 A / dm ^{2 and the treatment time was 360 seconds.} Table 1 shows the thickness, aperture ratio, hole diameter, hole density, air permeability, and water pressure resistance of the obtained breathable waterproof metal leaf.

[Example 4]
The conditions for contacting the aluminum support with the aqueous sodium hydroxide solution by the dipping method were set at 22 ° C. for 200 seconds, and the same as in Example 1 except that the metal type of the porous metal foil formed in the plating step was nickel. , Obtained breathable waterproof metal foil with support. The composition of the plating treatment liquid used was 340 g / L of nickel sulfate hexahydrate and 40 g / L of boric acid, which were adjusted to pH 4.5. The current density in the nickel electroplating treatment was 1.5 A / dm ² , and the treatment time was 888 seconds. The treatment temperature was 40 ° C. Table 1 shows the thickness, aperture ratio, hole diameter, hole density, air permeability, and water pressure resistance of the obtained breathable waterproof metal leaf.

[Comparative Example 1]
A breathable waterproof metal leaf with a support was obtained in the same manner as in Example 1 except that the current density in the first-stage electrolytic copper plating step was 2.0 A / dm ^2. Table 1 shows the thickness, aperture ratio, hole diameter, hole density, air permeability, and water pressure resistance of the obtained breathable waterproof metal leaf.

[Comparative Example 2]
VERZONE SF-310 (manufactured by Yamato Kasei Co., Ltd.) was replaced with a 100 mL / L aqueous solution, and was immersed in a 20 mL / L aqueous solution of PAL C (Tatsuta Densen Co., Ltd.) at 22 ° C for 30 seconds to prevent rust. , A breathable waterproof metal leaf with a support was obtained in the same manner as in Example 2. Table 1 shows the thickness, aperture ratio, hole diameter, hole density, air permeability, and water pressure resistance of the obtained breathable waterproof metal leaf.

Claims (2)

1- [N, N-bis (2-ethylhexyl)) on at least one surface of a metal leaf having fine pores having a diameter of 30 μm or less and a pore density of 100 pieces / mm ^{2 or less and the metal foil.} A water-repellent film containing aminomethyl) benzotriazole or 1- [N, N-bis (2-ethylhexyl) aminomethyl] methylbenzotriazole as the main component and having a water contact angle of 70 ° or more is laminated and ventilated. A breathable waterproof metal leaf having a degree of 38 sec / 100 mL or more and 1200 sec / 100 mL or less. The breathable waterproof metal leaf according to claim 1 or 2, wherein the water pressure resistance is 50 gf / cm ^{2 or more.}

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