Method for manufacturing foil material

Abstract

A method for manufacturing a foil material. A release film is adhered to raw foil, such that the stability of the raw foil can be improved, thereby effectively ameliorating the problem of torn edges of the raw foil when the raw foil is peeled off from a roller body.

Description

A method for preparing foil

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202311395742.4, filed on October 25, 2023, entitled “A method for preparing foil,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the technical field of secondary batteries, and in particular to a method for preparing a foil. Background Art

[0004] In secondary batteries, the current collector is the carrier for electron energy transfer. Copper foil is typically used for the negative electrode current collector. As performance requirements for secondary batteries increase, copper foil thickness is becoming increasingly thinner. However, when using electrolytic methods to produce copper foil, excessively thin foil is difficult to peel from the cathode roll and is prone to tearing, making it difficult to produce thinner copper foil.

[0005] Therefore, how to improve the edge tearing problem of copper foil has become an important research topic.

[0006] Summary of the Invention

[0007] In view of the problems existing in the background technology, the present application provides a method for preparing a foil material, which can effectively improve the problem of edge tearing when peeling the foil material from a roller body.

[0008] The method for preparing a foil provided in the first aspect of the present application comprises the following steps:

[0009] The green foil is formed on the roller body by electrolysis;

[0010] Adhere a release film to the raw foil;

[0011] Peeling the raw foil and the release film off the roller;

[0012] Remove the release film.

[0013] By adhering a release film to the raw foil, this application improves the stability of the raw foil, effectively reducing the problem of tearing when peeling the raw foil from the roll. The release film can be removed from the raw foil later without affecting its performance. This method enables the production of thinner raw foil, especially ultra-thin raw foil. Compared with existing production methods, it can increase the width of the raw foil, improving the quality and performance of the raw foil.

[0014] In some embodiments, according to a first example of the first aspect, before removing the release film, the peel strength between the release film and the raw foil is greater than 1 N / 25 mm, preferably 1-5 N / 25 mm. During the removal of the release film, the peel strength between the release film and the raw foil is less than 0.3 N / 25 mm.

[0015] The release film used in this application can be removed after treatment under certain conditions. By optimizing the peel strength between the release film and the raw foil within the above range, this application can not only peel the raw foil and the release film together from the roll, improving the problem of raw foil tearing, but also remove the release film from the raw foil surface after peeling, reducing the amount of release film residue.

[0016] In some embodiments, according to the first aspect, a second example of the first aspect is provided, wherein the release film includes a UV adhesion-reducing film.

[0017] By optimizing the type of release film, it is easier and quicker to remove it after the peeling step, which can reduce damage to the raw foil.

[0018] In some embodiments, according to the first aspect, a third example of the first aspect is proposed, and removing the release film includes: changing at least one of the following conditions: light energy, light wavelength, and illumination time, so that the peeling strength between the release film and the raw foil is reduced to below 0.3N / 25mm, thereby removing the release film.

[0019] The release film of the present application is easy to remove, has a simple process, is convenient to operate, and is suitable for large-scale industrial production.

[0020] In some embodiments, according to the first aspect, providing a fourth example of the first aspect, the release film covers the entire surface of the raw foil.

[0021] Adhering the release film to the entire surface of the raw foil is conducive to the complete peeling of the raw foil, improving the problems of tearing and breaking of the foil, and can produce a roll of raw foil with a length of more than 10,000 meters without the risk of tearing or breaking of the foil in the middle.

[0022] In some embodiments, according to the first aspect, providing a fifth example of the first aspect, the thickness of the raw foil is 1-2 μm.

[0023] The thinner the raw foil, the more likely it is to tear or break. However, the method of the present application can produce ultra-thin raw foil with a thickness of 1-2 μm, which is less prone to tearing or breaking, thus overcoming the difficulty in producing ultra-thin raw foil.

[0024] In some embodiments, according to the first aspect, a sixth example of the first aspect is provided, which further includes: forming a transition metal layer on the surface of the raw foil after peeling and before removing the release film.

[0025] By forming a transition metal layer on the surface of the raw foil, an alloy foil can be obtained. This can not only improve the strength of the raw foil, such as tensile strength, thereby improving the mechanical properties of the raw foil; it can also cover some small defects on the raw foil (such as pinholes and small holes), thereby improving the quality of the raw foil; it can also increase the thickness and corrosion resistance of the raw foil.

[0026] In some embodiments, according to the first aspect, a seventh example of the first aspect is provided, wherein the material of the transition metal layer includes one or more of nickel and molybdenum.

[0027] By optimizing the material of the transition metal layer, the strength of the raw foil can be improved and high-quality raw foil can be obtained.

[0028] In some embodiments, according to the first aspect, an eighth example of the first aspect is provided, wherein the thickness of the transition metal layer is 20-100 nm.

[0029] Controlling the thickness of the transition metal layer within the above range is beneficial to enhancing the mechanical properties of the alloy foil.

[0030] In some embodiments, according to the first aspect, a ninth example of the first aspect is provided, wherein the transition metal layer is formed by sputtering. Optionally, the sputtering method includes one or more of magnetron sputtering, direct current sputtering, and radio frequency sputtering.

[0031] Compared with the electroplating method, the sputtering method is used to form the transition metal layer, which is beneficial for better covering some small defects on the raw foil (such as pinholes and small holes) and improving the tensile strength and quality of the raw foil.

[0032] In some embodiments, according to the first aspect, a tenth example of the first aspect is provided, which further includes: after peeling and before removing the release film;

[0033] forming a transition metal layer on the surface of the raw foil to obtain a composite structure, which sequentially includes the transition metal layer, the raw foil and the release film;

[0034] The composite structure is fixed on both sides of the base film to obtain a sandwich structure, wherein the transition metal layer is close to the base film and the release film is far away from the base film.

[0035] A composite foil can be obtained by this technical solution, wherein the raw foil and the transition metal layer constitute an alloy layer, and a base film is provided between the two alloy layers, which can improve the overall tensile strength of the alloy layer.

[0036] In some embodiments, according to the first aspect, an eleventh example of the first aspect is provided, which further includes: after peeling and before removing the release film;

[0037] forming a transition metal layer on the surface of the raw foil;

[0038] adhering a release film to the transition metal layer;

[0039] removing the release film on the green foil to obtain a composite structure comprising the green foil, the transition metal layer, and the release film in sequence;

[0040] The composite structure is fixed on both sides of the base film to obtain a sandwich structure, in which the raw foil is close to the base film and the release film is far away from the base film.

[0041] This technical solution can be used to obtain a composite foil of another structure, wherein the raw foil and the transition metal layer constitute an alloy layer, and a base film is provided between the two alloy layers, which can improve the overall tensile strength of the alloy layer (including the raw foil and the transition metal layer).

[0042] In some embodiments, according to the first aspect, a twelfth example of the first aspect is provided, and fixing includes adhering with an adhesive.

[0043] The composite structure is adhered to both sides of the base film using adhesive, which is simple to operate and saves costs.

[0044] In some embodiments, according to the first aspect, a thirteenth example of the first aspect is provided, wherein after obtaining the sandwich structure and before removing the release film, the method further includes: semi-curing the sandwich structure. After removing the release film, the method further includes: curing.

[0045] Semi-curing and curing are beneficial to combining the base film and the composite structure more firmly, thereby improving the overall stability and tensile strength of the composite foil.

[0046] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0048] 1 to 4 are schematic diagrams of structures obtained in various steps of preparing a composite foil according to an embodiment of the present application.

[0049] 5 to 10 are schematic diagrams of structures obtained by various steps of preparing a composite foil according to another embodiment of the present application.

[0050] Description of reference numerals:

[0051] 100 is copper foil, 200 is release film, 300 is transition metal layer, 400 is base film, and 500 is adhesive layer. DETAILED DESCRIPTION

[0052] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the accompanying drawings are intended to cover non-exclusive inclusions.

[0054] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and similarly, any upper limit can be combined with any other upper limit to form an unspecified range. In addition, although not explicitly stated, each point or individual value between the endpoints of a range is included in the range. Thus, each point or individual value can serve as its own lower limit or upper limit and be combined with any other point or individual value, or with other lower limits or upper limits, to form an unspecified range.

[0055] In the description of this article, it should be noted that, unless otherwise specified, “above” and “below” are inclusive of the number itself, and “multiple” in “one or more” means more than two (including two).

[0056] The above summary of the invention of this application is not intended to describe every disclosed embodiment or every implementation in this application. The following description more specifically illustrates exemplary embodiments. In many places throughout the application, guidance is provided by a series of examples, which can be used in various combinations. In each example, the enumeration is intended only as a representative group and should not be construed as exhaustive.

[0057] In secondary batteries, the current collector is the carrier for electron energy transfer. Copper foil is typically used for the negative electrode current collector. As performance requirements for secondary batteries increase, copper foil thickness is becoming increasingly thinner. However, when using electrolytic methods to produce copper foil, excessively thin foil is difficult to peel from the cathode roll and is prone to tearing, making it difficult to produce thinner copper foil.

[0058] The main cause of copper foil tearing is excessive bonding between the copper foil and the end of the cathode roller when the copper foil is peeled from the cathode roller surface. On the one hand, because the entire cathode roller is energized and immersed in the electrolyte, an electrolytic copper layer inevitably deposits on the end of the cathode roller, making it difficult to peel the copper foil from the end of the cathode roller. On the other hand, poorly polished cathode roller ends, damage to the right angles of the cathode roller ends, and low polished end surface finish can also cause excessive bonding between the cathode roller and the copper foil at the roller end. To address the problem of copper deposition on the cathode roller end, the cathode roller end is generally sealed to prevent the electrolyte from contacting the cathode roller end and reduce copper deposition. However, complete sealing of the cathode roller end is not easy to achieve.

[0059] Therefore, how to improve the edge tearing problem of copper foil has become an important research topic.

[0060] To address the aforementioned issues, this application provides a novel method for preparing foil, wherein a release film is adhered to a raw foil roll, and the raw foil and the release film are peeled off the roll together. The release film improves the stability of the raw foil, effectively reducing the tearing problem of the raw foil when peeling it from the roll.

[0061] Specifically, the first aspect of the present application provides a method for preparing a foil, comprising the following steps:

[0062] The green foil is formed on the roller body by electrolysis;

[0063] Adhere a release film to the raw foil;

[0064] Peeling the raw foil and the release film off the roller;

[0065] Remove the release film.

[0066] In this application, "release film" refers to an adhesive film that can be removed after treatment under certain conditions. The peel strength between the release film and the raw foil can vary depending on the conditions. The peel strength of the release film will change when at least one of the following conditions is changed: light energy, light wavelength, and light exposure time.

[0067] By adhering a release film to the raw foil, this application improves the stability of the raw foil, effectively reducing the problem of tearing when peeling the raw foil from the roll. The release film can be removed from the raw foil later without affecting its performance. This method enables the production of thinner raw foil, especially ultra-thin raw foil. Compared with existing production methods, it can increase the width of the raw foil, improving the quality and performance of the raw foil.

[0068] In some embodiments, before removing the release film, the peel strength between the release film and the raw foil may be greater than 1 N / 25 mm, preferably 1-5 N / 25 mm. During the removal of the release film, the peel strength between the release film and the raw foil may be less than 0.3 N / 25 mm.

[0069] By optimizing the peel strength of the release film within the above range, the present application can not only peel the raw foil and the release film from the roller together, thereby improving the problems of raw foil tearing and tape breakage, but also remove the release film from the surface of the raw foil after peeling, thereby reducing the release film residue.

[0070] If the release film is a UV-resistant film and the peel strength between the release film and the raw foil is too high before removal, high light energy is required to reduce the peel strength. Otherwise, the release film cannot be completely removed from the raw foil. However, ultra-thin copper foil limits the light energy to a low level, which results in the release film not being completely removed from the raw foil even with insufficient light energy. If the peel strength between the release film and the raw foil is too low before removal, the raw foil will still tear when it is peeled from the cathode roller.

[0071] In some specific embodiments, before removing the release film, the peel strength between the release film and the green foil may be 1N / 25mm, 1.5N / 25mm, 2N / 25mm, 2.5N / 25mm, 3N / 25mm, 3.5N / 25mm, 4N / 25mm, 4.5N / 25mm or 5N / 25mm.

[0072] In some specific embodiments, during the process of removing the release film, the peel strength between the release film and the raw foil may be 0.3 N / 25 mm, 0.2 N / 25 mm, 0.1 N / 25 mm, or 0 N / 25 mm.

[0073] In some embodiments, the release film includes a UV anti-viscosity film, which is a special adhesive tape that has strong adhesion under normal conditions and whose adhesion decreases sharply after being irradiated with UV light.

[0074] By optimizing the type of release film, it is easier and quicker to remove it after the peeling step, which can reduce damage to the raw foil.

[0075] In some specific embodiments, the thickness of the release film may be 1-10 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm. Before removing the release film, the peel strength between the release film and the raw foil increases with increasing thickness of the release film.

[0076] In some embodiments, removing the release film includes: changing at least one of the following conditions: light energy, light wavelength, and illumination time, so that the peel strength between the release film and the raw foil is reduced to below 0.3N / 25mm, thereby removing the release film.

[0077] The release film of the present application is easy to remove, has a simple process, is convenient to operate, and is suitable for large-scale industrial production.

[0078] In some specific embodiments, the release film is removed by changing the conditions to reduce the peel strength between the release film and the raw foil to 0.3 N / 25 mm, 0.2 N / 25 mm, 0.1 N / 25 mm, or 0 N / 25 mm.

[0079] In some specific embodiments, when the release film is a UV-reducing film, it can be removed by ultraviolet (UV) irradiation. The energy and time of UV irradiation are not particularly limited in this application, as long as the UV-reducing film can be removed.

[0080] In some embodiments, the release film covers the entire surface of the green foil.

[0081] Adhering the release film to the entire surface of the raw foil (the surface facing away from the roll) facilitates complete peeling of the raw foil, reducing edge tearing and tape breakage issues. This allows for rolls of copper foil exceeding 10,000 meters in length, minimizing the risk of tearing or tape breakage. If the release film covers a portion of the raw foil surface, the uncovered portion may tear during peeling, leading to edge tearing and tape breakage. Therefore, it is preferred that the release film cover the entire surface of the raw foil.

[0082] In some embodiments, the raw foil is copper foil. Forming the raw foil on the roller includes forming the copper foil raw foil on the roller using an electrolyte. The electrolyte may include: 70-90 g / L copper ions, 90-120 g / L sulfuric acid, 20-50 mg / L chloride ions, 3-20 mg / L brightener, 30-200 mg / L inhibitor, and 30-200 mg / L leveler. The brightener includes one or more of sodium polydisulfide propane sulfonate (SPS), sodium 3-mercaptopropane sulfonate (MPS), and sodium N,N-dimethyldithiocarbonylpropane sulfonate (DPS). The inhibitor includes one or more of polyethylene glycol (PEG) and hydroxyethyl cellulose (HEC). The leveler includes one or more of low molecular weight collagen (e.g., collagen 3000), gelatin, and a nitrogen-containing heterocyclic quaternary ammonium salt.

[0083] The electrolyte formula is related to the properties of the resulting copper foil. This application optimizes the electrolyte formula to reduce holes in the copper foil, enhance its mechanical properties, improve its tensile strength, and improve edge tearing and breakage problems, thereby improving the quality of the copper foil.

[0084] In some embodiments, the green foil may have a thickness of 1-2 μm.

[0085] The thinner the raw foil, the more likely it is to tear or break. However, the method of the present application can produce ultra-thin raw foil with a thickness of 1-2 μm, which is less prone to tearing or breaking, thus overcoming the difficulty in producing ultra-thin raw foil.

[0086] In some specific embodiments, the green foil may have a thickness of 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, or 2 μm.

[0087] In some embodiments, after the peeling and before the release film is removed, the method further includes: forming a transition metal layer on the surface of the raw foil.

[0088] By forming a transition metal layer on the surface of the raw foil, an alloy foil can be obtained. This can not only improve the strength of the raw foil, such as tensile strength, thereby improving the mechanical properties of the copper raw foil; it can also cover some small defects on the raw foil (such as pinholes and small holes), thereby improving the quality of the raw foil; it can also increase the thickness and corrosion resistance of the raw foil.

[0089] In some embodiments, the material of the transition metal layer may include one or more of nickel and molybdenum.

[0090] By optimizing the material of the transition metal layer, the strength of the raw foil (such as tensile strength) can be improved, thereby obtaining high-quality raw foil.

[0091] In some specific embodiments, the raw foil may be copper foil, and the transition metal layer may include nickel. The resulting copper-nickel alloy foil has high tensile strength and strong corrosion resistance.

[0092] In some embodiments, the transition metal layer may have a thickness of 20-100 nm.

[0093] Controlling the thickness of the transition metal layer within the above range is beneficial to enhancing the mechanical properties of the alloy.

[0094] In some specific embodiments, the thickness of the transition metal layer may be 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm. As the thickness of the transition metal layer increases, the tensile strength of the alloy foil increases accordingly. However, if the thickness of the transition metal layer is too great, the improvement in the tensile strength of the raw foil is no longer significant, and production costs may increase. Therefore, the thickness of the transition metal layer is controlled within the range of 20-100 nm in this application.

[0095] In some embodiments, the transition metal layer is formed by sputtering, which may include one or more of magnetron sputtering, direct current sputtering, and radio frequency sputtering.

[0096] Compared with the electroplating method, the sputtering method is used to form the transition metal layer, which is conducive to better covering some small defects on the raw foil (such as pinholes and small holes), obtaining a uniform transition metal layer, and improving the tensile strength and quality of the raw foil.

[0097] In some embodiments, after peeling and before removing the release film, the method further comprises:

[0098] forming a transition metal layer on the surface of the raw foil to obtain a composite structure, which sequentially includes the transition metal layer, the raw foil and the release film;

[0099] The composite structure is fixed on both sides of the base film to obtain a sandwich structure, wherein the transition metal layer is close to the base film and the release film is far away from the base film.

[0100] This technical solution yields a composite foil in which the raw foil and transition metal layer form an alloy layer, with a base film positioned between the two alloy layers to enhance the overall tensile strength of the alloy layer. Specifically, the composite copper foil comprises, from top to bottom, a stacked arrangement of raw foil, a transition metal layer, a base film, a transition metal layer, and the raw foil.

[0101] In some embodiments, after peeling and before removing the release film, the method further comprises:

[0102] forming a transition metal layer on the surface of the raw foil;

[0103] adhering a release film to the transition metal layer;

[0104] removing the release film on the green foil to obtain a composite structure comprising the green foil, the transition metal layer, and the release film in sequence;

[0105] The composite structure is fixed on both sides of the base film to obtain a sandwich structure, in which the raw foil is close to the base film and the release film is far away from the base film.

[0106] This technical solution yields a composite foil structure in which the raw foil and transition metal layer form an alloy layer, with a base film disposed between the two alloy layers. This enhances the overall tensile strength of the alloy layer (including the raw foil and transition metal layer). Specifically, the composite copper foil comprises, from top to bottom, a stacked transition metal layer, raw foil, base film, raw foil, and transition metal layer.

[0107] In some embodiments, the fixing includes adhesive adhesion. By applying adhesive on both surfaces of the base film, the composite structure can be firmly fixed to both sides of the base film, so that the base film and the composite structure are better combined, the overall tensile strength is improved, the operation is simple, and the cost is saved.

[0108] In some specific embodiments, the adhesive may include one or more of epoxy resin and maleic anhydride-modified polyolefin (eg, maleic anhydride-modified polypropylene).

[0109] In some embodiments, after obtaining the sandwich structure and before removing the release film, the process further includes semi-curing the sandwich structure. After removing the release film, the process further includes curing the sandwich structure. Semi-curing includes maintaining the temperature at 70-90°C in a nitrogen or inert gas atmosphere. Curing includes maintaining the temperature at 70-90°C in a nitrogen or inert gas atmosphere.

[0110] Semi-curing and curing are beneficial to combining the base film and the composite structure more firmly, thereby improving the overall stability and tensile strength of the composite foil.

[0111] In some embodiments, the material of the base film may include one or more of polyethylene terephthalate, polypropylene, etc.

[0112] In some embodiments, the base film may have a thickness of 2-6 μm, for example, 2 μm, 2.5 μm, 2.9 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, or 6 μm. A thin base film can reduce the overall thickness of the composite foil.

[0113] The present application will be further described below with reference to the examples. The following examples describe the present disclosure in more detail. These examples are intended for illustrative purposes only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise stated, all reagents used in the examples are commercially available or synthesized according to conventional methods, and all instruments used in the examples are commercially available.

[0114] Preparation of copper foil

[0115] Example 1

[0116] (1) Preparation of electrolyte

[0117] The electrolyte composition is: copper ion 70-90g / L, sulfuric acid 90-120g / L, chloride ion 20-50mg / L, brightener 3-20mg / L, inhibitor 30-200mg / L, and leveler 30-200mg / L. The brightener is sodium polydisulfide (SPS), the inhibitor is polyethylene glycol (PEG), and the leveler is gelatin.

[0118] (2) Preparation of electrolytic copper foil

[0119] Electrolytic copper foil with a thickness of 1.5 μm was prepared by adjusting the current and cathode roller speed: the cathode roller diameter was 2.7 m, the speed was 8 m / min, and the current was 5700 A.

[0120] (3) Adhesion of UV anti-viscosity film

[0121] Prepare a UV coating solution with a 20wt% solids content: Weigh the UV coating solution (powdered material, purchased from China Lucky Group Co., Ltd.) using a weighing instrument, add ethyl acetate solvent, and stir for 20 minutes to obtain a 20wt% solids content UV coating solution. After standing for 10 minutes to degas, apply it to a PET substrate using a coater. Dry in an 80°C arch oven to completely evaporate the solvent, leaving a smooth coating with a width equal to the width of the cathode roller and a thickness of 2μm. The UV coating is then adhered to the matte surface of the raw foil using a laminating roller.

[0122] Before peeling, test the peel strength between the UV anti-viscosity film and the electrolytic copper foil. The test method includes the following steps:

[0123] ① After adhering the UV anti-viscosity film to the rough surface of the raw foil, cut a sample from the cathode roller (the sample includes the raw foil and the UV anti-viscosity film adhered to the raw foil) and use a sampling slicer to cut it into strips with a length and width of 25mm×100mm respectively.

[0124] ② Use 3M double-sided tape to stick the sample on the glass plate and use a 2Kg push roller to roll it back and forth three times.

[0125] ③ Use 3M transparent tape to peel off the sample 10mm long. Then use the high-speed rail tensile testing machine to test the peel strength. The test uses the 90-degree peel method. The basic parameters of the high-speed rail tensile testing machine are: 100mm clamp spacing, 50mm / min speed.

[0126] (4) Peeling

[0127] The copper foil and the release film are peeled off from the cathode roller.

[0128] (5) Remove UV anti-viscosity film

[0129] After UV irradiation of the UV anti-viscosity film, the UV anti-viscosity film is removed to obtain copper foil. After UV irradiation, the peel strength between the UV anti-viscosity film and the electrolytic copper foil is measured. This peel strength is the peel strength between the UV anti-viscosity film and the raw foil during the removal of the UV anti-viscosity film. The peel strength test method is as follows:

[0130] ① After UV irradiation, a sample is cut from the cathode roller (the sample includes the raw foil and the UV anti-sticking film adhered to the raw foil) and sliced ​​into samples with a length and width of 25 mm × 100 mm using a sampling slicer.

[0131] ② Use 3M double-sided tape to stick the sample on the glass plate and use a 2Kg push roller to roll it back and forth three times.

[0132] ③ Use 3M transparent tape to peel off the sample 10mm long. Then use the high-speed rail tensile testing machine to test the peel strength. The test uses the 90-degree peel method. The basic parameters of the high-speed rail tensile testing machine are: 100mm clamp spacing, 50mm / min speed.

[0133] Examples 2-5

[0134] The method described in Example 1 was followed, except that, before peeling, the peel strength between the UV anti-viscosity film and the electrolytic copper foil was different from that in Example 1, and the peel strength between the release film and the raw foil increased with increasing thickness of the release film, as shown in Table 1 below.

[0135] Table 1

[0136] Examples 6-8

[0137] The method described in Example 1 was followed, except that during the ultraviolet light irradiation, the peel strength between the UV anti-viscosity film and the electrolytic copper foil was different from that in Example 1, as shown in Table 2 below.

[0138] Table 2

[0139] Examples 9-11

[0140] The method described in Example 1 was followed, except that an electrolytic copper foil having a thickness different from that of Example 1 was prepared by adjusting the current and the linear speed of the cathode roller, as shown in Table 3 below.

[0141] The thickness of the copper foil is positively correlated with the current and negatively correlated with the cathode roller speed. Thickness calculation formula:

[0142] Copper foil thickness (μm) = copper electrochemical equivalent × current × electroplating efficiency ÷ cathode roller speed ÷ copper density ÷ cathode roller width ÷ 60. The copper electrochemical equivalent is 1.186g / AH, the electroplating efficiency is 98%, and the copper density is 8.95g / cm 3 The cathode roller width is 1.02m. The copper foil thickness is controlled by adjusting the current and the cathode roller speed. For example, the parameters for producing 1μm thick copper foil are: current 4500A, cathode roller speed 9.5m / min. The parameters for producing 1.5μm thick copper foil are: current 4500A, cathode roller speed 6.3m / min.

[0143] Table 3

[0144] Comparative Example 1

[0145] The method described in Example 1 was followed, except that no UV adhesive reduction film was adhered and the copper foil was directly peeled off from the cathode roller.

[0146] Tear area test of raw foil

[0147] Tear area test:

[0148] The tearing was primarily concentrated along the cathode roller edge, exposing the roller in this area. Tear area percentage = tear width / cathode roller width × 100%. Tear width = cathode roller width - copper foil width, where the copper foil width is the smallest width of the cathode roller, i.e., the narrowest part of the copper foil. The results are shown in Table 4 below.

[0149] Table 4

[0150] It can be seen from the above embodiments and comparative examples that the present application can improve the stability of the electrolytic copper foil by adhering a release film to the electrolytic copper foil, so that when the electrolytic copper foil is peeled off from the cathode roller, the tearing problem of the electrolytic copper foil can be effectively improved and the tearing area can be reduced.

[0151] Preparation of alloy foil

[0152] Example 12

[0153] (1) Preparation of electrolyte

[0154] Same as Example 1.

[0155] (2) Preparation of electrolytic copper foil

[0156] Same as Example 1.

[0157] (3) Adhesion of UV anti-viscosity film

[0158] Same as Example 1.

[0159] (4) Peeling

[0160] Same as Example 1.

[0161] (5) Formation of nickel layer

[0162] A nickel layer is formed on the surface of the electrolytic copper foil by magnetron sputtering, and the thickness of the nickel layer is 20 nm.

[0163] (6) Remove UV anti-viscosity film

[0164] The UV anti-viscosity film is irradiated with 30% power ultraviolet light, with an energy of 600mJ / cm 2 , remove the UV anti-viscosity film and obtain the copper-nickel alloy foil.

[0165] Example 13

[0166] The method described in Example 12 was followed, except that the type of transition metal layer was different from that in Example 12, as shown in Table 5 below.

[0167] Table 5

[0168] Examples 14-17

[0169] The method described in Example 12 was followed, except that the thickness of the transition metal layer was different from that in Example 12, as shown in Table 6 below.

[0170] Table 6

[0171] Example 18

[0172] The method described in Example 12 was followed, except that the method for forming the nickel layer was different from that in Example 12, as shown in Table 7 below.

[0173] Table 7

[0174] Alloy foil strength test

[0175] Tensile strength test:

[0176] The sample was punched into a 15 mm wide and 150 mm long sample. Tensile testing was performed using a high-speed rail tensile tester at room temperature and pressure (25°C, 0.1 MPa). The initial length was set to 50 mm, and the tensile test was performed at a rate of 5 mm / min until the sample broke. The maximum tensile force F at break was recorded, and the tensile strength of the organic support layer was calculated using T = F / S. S is the initial cross-sectional area of ​​the sample, which is equal to the product of the sample width and the sample thickness. The test results are shown in Table 8 below.

[0177] Table 8

[0178] It can be seen from the above examples that high-strength alloy foil can be obtained by adopting the method of the present application.

[0179] Preparation of composite copper foil

[0180] Example 19

[0181] (1) Preparation of electrolyte

[0182] Same as Example 12.

[0183] (2) Preparation of electrolytic copper foil

[0184] Same as Example 12.

[0185] (3) Adhesion of UV anti-viscosity film

[0186] Same as Example 12.

[0187] (4) Peeling

[0188] Same as Example 12. The obtained structure is shown in FIG1 , including an electrolytic copper foil 100 and a release film 200 (ie, a UV anti-viscosity film).

[0189] (5) Formation of nickel layer

[0190] Same as Example 12. A composite structure as shown in FIG2 is obtained, comprising an electrolytic copper foil 100, a release film 200 (ie, a UV adhesion-reducing film), and a transition metal layer 300 (ie, a nickel layer).

[0191] (6) Preparation of sandwich structure

[0192] Epoxy resin adhesive was evenly coated on both surfaces of a 2.9 μm thick polypropylene (PP) base film 400 to form an adhesive layer 500. The composite structure obtained in step (5) was adhered to both surfaces of the PP base film to obtain a sandwich structure as shown in FIG3 , in which the nickel layer was close to the base film.

[0193] (7) Semi-cooking

[0194] Set the temperature of the oven filled with nitrogen or inert gas to 80°C and bake for 24 hours.

[0195] (8) Remove UV anti-viscosity film

[0196] The UV anti-viscosity film is irradiated with 30% power ultraviolet light, with an energy of 600mJ / cm 2 , remove the UV anti-viscosity film to obtain the composite copper foil shown in Figure 4.

[0197] (9) Ripening

[0198] Set the temperature of an oven filled with nitrogen or inert gas to 80°C and bake and keep warm for 72 hours to allow the adhesive to solidify and the molecular chains to solidify completely.

[0199] Example 20

[0200] (1) Preparation of electrolyte

[0201] Same as Example 12.

[0202] (2) Preparation of electrolytic copper foil

[0203] Same as Example 12.

[0204] (3) Adhesion of UV anti-viscosity film

[0205] Same as Example 12.

[0206] (4) Peeling

[0207] Same as Example 12. The obtained structure is shown in FIG5 , including an electrolytic copper foil 100 and a release film 200 (ie, a UV anti-viscosity film).

[0208] (5) Formation of nickel layer

[0209] Same as Example 12. A structure as shown in FIG6 is obtained, including an electrolytic copper foil 100, a release film 200 (ie, a UV anti-viscosity film), and a transition metal layer 300 (ie, a nickel layer).

[0210] (6) Preparation of sandwich structure

[0211] A UV anti-viscosity film is attached to the nickel layer to obtain the structure shown in Figure 7. The UV anti-viscosity film on the electrolytic copper foil is then irradiated with 30% UV light with an energy of 600 mJ / cm 2 , thereby removing the UV adhesive reduction film on the electrolytic copper foil, resulting in a composite structure as shown in Figure 8. Epoxy resin adhesive was evenly coated on both surfaces of a 2.9 nm thick polypropylene (PP) base film 400 to form adhesive layer 500. The composite structure was adhered to both surfaces of a PET base film, resulting in a sandwich structure as shown in Figure 9.

[0212] (7) Semi-cooking

[0213] Set the temperature of the oven filled with nitrogen or inert gas to 80°C and bake for 24 hours.

[0214] (8) Remove UV anti-viscosity film

[0215] The UV anti-viscosity film is irradiated with 30% power ultraviolet light, with an energy of 600mJ / cm 2 , remove the UV anti-viscosity film to obtain the composite copper foil shown in Figure 10.

[0216] (9) Ripening

[0217] Set the temperature of an oven filled with nitrogen or inert gas to 80°C and bake and keep warm for 72 hours to allow the adhesive to cross-link and cure, and the molecular chains to cure completely.

[0218] Example 21

[0219] The method described in Example 19 was followed, except that no par-cooking and aging were performed.

[0220] Strength test of composite copper foil

[0221] Tensile strength test:

[0222] The sample was punched into a 15 mm wide and 150 mm long sample. Tensile testing was performed using a high-speed rail tensile tester at room temperature and pressure (25°C, 0.1 MPa). The initial length was set to 50 mm, and the tensile test was performed at a rate of 5 mm / min until the sample broke. The maximum tensile force F applied to the sample at break was recorded, and the tensile strength of the organic support layer was calculated using T = F / S. S is the initial cross-sectional area of ​​the sample, which is equal to the product of the sample width and thickness. The test results are shown in Table 9 below.

[0223] Table 9

[0224] It can be seen from the above embodiments and comparative examples that a high-strength composite copper foil can be obtained by adopting the method of the present application.

[0225] The foregoing description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be readily conceived by a person skilled in the art within the technical scope disclosed herein are intended to be encompassed within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A method for preparing a foil, characterized in that: The following steps are involved: The green foil is formed on the roll body by electrolysis; adhering a release film to the raw foil; peeling the raw foil and the release film off the roller body; The release film is removed.

2. The method according to claim 1, characterized in that: Before removing the release film, the peel strength between the release film and the raw foil is 1N / 25mm or more, preferably 1-5N / 25mm; During the process of removing the release film, the peeling strength between the release film and the raw foil is less than 0.3 N / 25 mm.

3. The method according to any one of claims 1 to 2, characterized in that: The release film includes a UV anti-adhesion film.

4. The method according to any one of claims 1 to 3, characterized in that: Removing the release film includes: changing at least one of the following conditions: light energy, light wavelength, and light exposure time, so that the peeling strength between the release film and the raw foil is reduced to less than 0.3N / 25mm, thereby removing the release film.

5. The method according to any one of claims 1 to 4, characterized in that: The release film covers the entire surface of the green foil.

6. The method according to any one of claims 1 to 5, characterized in that: The green foil has a thickness of 1-2 μm.

7. The method according to any one of claims 1 to 6, characterized in that: After the peeling and before the release film is removed, the method further includes: forming a transition metal layer on the surface of the raw foil.

8. The method according to claim 7, characterized in that The material of the transition metal layer includes one or more of nickel and molybdenum.

9. The method according to claim 7 or 8, characterized in that: The thickness of the transition metal layer is 20-100 nm.

10. The method according to any one of claims 7 to 9, characterized in that: The transition metal layer is formed by sputtering; optionally, the sputtering method includes one or more of magnetron sputtering, direct current sputtering, and radio frequency sputtering.

11. The method according to any one of claims 1 to 10, characterized in that: After peeling and before removing the release film, the method further comprises: forming a transition metal layer on the surface of the raw foil to obtain a composite structure, which sequentially comprises the transition metal layer, the raw foil and the release film; The composite structure is fixed on both sides of the base film to obtain a sandwich structure, wherein the transition metal layer is close to the base film and the release film is far away from the base film.

12. The method according to any one of claims 1 to 10, characterized in that: After peeling and before removing the release film, the method further comprises: forming a transition metal layer on the surface of the raw foil; Adhering the release film on the transition metal layer; removing the release film on the raw foil to obtain a composite structure, which sequentially comprises the raw foil, the transition metal layer and the release film; The composite structure is fixed on both sides of the base film to obtain a sandwich structure, wherein the raw foil is close to the base film and the release film is far away from the base film.

13. The method according to claim 11 or 12, characterized in that: The fixing includes adhering with an adhesive.

14. The method according to claim 11 or 12, characterized in that: After obtaining the sandwich structure and before removing the release film, the method further includes: semi-cooking the sandwich structure; After removing the release film, the method further includes: performing aging.

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