Preparation method of composite membrane and composite membrane

Abstract

The invention discloses a preparation method of a composite membrane and the composite membrane. The preparation method of the composite membrane comprises a step S1 and a step S2. The method comprises the steps that S1, a substrate layer is obtained, and a first surface and a second surface of the substrate layer are treated, so that the roughness of the first surface and the roughness of the second surface reach a first preset value R, and the dyne value of the first surface and the dyne value of the second surface reach a second preset value D; and S2, the substrate layer is placed in a coating cavity of vacuum coating equipment, and the coating rate of the vacuum coating equipment is controlled, so that coatings with the surface density reaching a third preset value sigma are prepared on the first surface and the second surface. The composite current collector can solve the problem that in the prior art, the binding force between the polymeric membrane layer and the surface plating layer is weak, and the polymeric membrane layer and the surface plating layer are easily separated in the using process of the composite current collector.

Description

Technical Field

[0001] The invention relates to the technical field of film preparation, and in particular to a method for preparing a composite film and the composite film. Background Art

[0002] The current collector is an important component of the battery. It carries the active materials, collects the electrons generated by the electrochemical reaction and conducts them to the external circuit.

[0003] At present, composite current collectors have received extensive attention and application in the new energy industry. Composite current collectors usually include a polymer film layer and a metal coating or non-metal coating deposited on the surface of the polymer film layer. Compared with traditional current collectors, composite current collectors have the characteristics of low cost and light weight. These characteristics enable composite current collectors to reduce the cost of batteries and improve the energy density and safety of batteries when used in batteries.

[0004] However, in the existing composite current collector, the bonding force between the polymer film layer and the surface coating is weak, which can easily lead to separation of the polymer film layer and the surface coating during use of the composite current collector, affecting the normal use of the composite current collector. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for preparing a composite film and a composite film to solve the problem in the prior art that the bonding force between the polymer film layer and the surface coating is weak, which easily leads to separation of the polymer film layer and the surface coating during use of the composite current collector.

[0006] According to one aspect of the present invention, there is provided a method for preparing a composite film, comprising:

[0007] Step S1: obtaining a base layer, and processing a first surface and a second surface of the base layer so that the roughness of the first surface and the second surface reaches a first predetermined value R, and the dyne value of the first surface and the second surface reaches a second predetermined value D;

[0008] Step S2: placing the base layer in a coating chamber of a vacuum coating device, and controlling the coating rate of the vacuum coating device to prepare a coating having a surface density reaching a third predetermined value ∑ on the first surface and the second surface.

[0009] Furthermore, the first predetermined value R satisfies the relationship: 0.07 μm≤R≤0.3 μm.

[0010] Furthermore, the second predetermined value D satisfies the relationship: D>40mN / m.

[0011] Furthermore, the third predetermined value ∑ satisfies the relationship: 1g / cm2 ≤∑≤20g / cm 2 .

[0012] Furthermore, the step S1 specifically includes the following steps:

[0013] S1.1: Processing the first surface and the second surface by chemical etching or laser etching so that the roughness of the first surface and the second surface reaches the first predetermined value R;

[0014] S1.2: treating the first surface and the second surface by corona treatment or plasma treatment, so that the dyne values ​​of the first surface and the second surface reach the second predetermined value D.

[0015] Further, in the step S2, the vacuum coating equipment is turned on, and the coating rate is controlled to be 10 m / min to 100 m / min, and the coating layer is prepared on the first surface and the second surface by magnetron sputtering; or,

[0016] In the step S2, the vacuum coating equipment is turned on, and the coating rate is controlled to be 70 m / min to 100 m / min, and the coating layer is prepared on the first surface and the second surface by a roller coating method; or,

[0017] In the step S2, the vacuum coating equipment is turned on, and the coating rate is controlled to be 100 m / min to 300 m / min, and the coating layer is prepared on the first surface and the second surface by a suspension coating method.

[0018] Furthermore, the base layer is prepared from one or more of polyethylene, polypropylene, ethylene propylene copolymer, polyethylene terephthalate, polyethylene naphthalate, poly(p-phenylene terephthalamide), acrylonitrile-butadiene-styrene copolymer, poly(p-phenylene terephthalamide), polypropylene, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber and polycarbonate.

[0019] Furthermore, the coating is made of one or more of copper, aluminum, copper alloy, aluminum alloy, nickel alloy, nickel, titanium alloy and titanium; or,

[0020] The coating is made of one or more of aluminum oxide and silicon nitride.

[0021] On the other hand, the present invention further provides a composite film, which is prepared by the composite film preparation method described above, and includes the base layer and the coating layer arranged on the first surface and the second surface.

[0022] Further, the roughness R of the first surface and the second surface satisfies the relationship: 0.07 μm≤R≤0.3 μm; and / or,

[0023] The dyne values ​​D of the first surface and the second surface satisfy the relationship: D>40mN / m; and / or,

[0024] The surface density ∑ of the coating satisfies the relationship: 1g / cm 2 ≤∑≤20g / cm 2 .

[0025] Further, along the thickness direction of the composite film, the thickness of the base layer is 3 μm to 8 μm; and / or,

[0026] Along the thickness direction of the composite film, the thickness of the coating is 50nm to 2000nm.

[0027] In the present invention, the change of the roughness and dyne value of the first surface and the second surface can improve the adsorption and bonding ability of the base layer to the coating layer, and the change of the coating surface density can improve the tightness between the coating layer and the base layer, thereby enhancing the bonding force between the base layer and the coating layer. Compared with directly sputtering or plating the coating layer on the base layer, the preparation method of the composite film of the present invention can improve the bonding force between the coating layer and the base layer, increase the difficulty of peeling the coating layer from the base layer, thereby extending the service life of the composite film. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0029] Figure 1 A schematic diagram of the structure of a composite membrane disclosed in an embodiment of the present invention;

[0030] Figure 2 The present invention is a flow chart of a method for preparing a composite membrane disclosed in an embodiment of the present invention.

[0031] The above drawings include the following reference numerals:

[0032] 10. Base layer; 101. First surface; 102. Second surface; 20. Coating. DETAILED DESCRIPTION

[0033] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0034] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0035] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0036] See also Figure 1 to Figure 2 As shown, the present invention provides a method for preparing a composite film, the preparation method comprising:

[0037] Step S1: obtaining a base layer 10, and processing a first surface 101 and a second surface 102 of the base layer 10 so that the roughness of the first surface 101 and the second surface 102 reaches a first predetermined value R, and the dyne value of the first surface 101 and the second surface 102 reaches a second predetermined value D;

[0038] Step S2: placing the base layer 10 in a coating chamber of a vacuum coating device, and controlling the coating rate of the vacuum coating device to prepare a coating layer 20 having a surface density reaching a third predetermined value ∑ on the first surface 101 and the second surface 102 .

[0039] In the present invention, when actually processing the composite film, it is necessary to first obtain the base layer 10, and the base layer 10 can be prepared or directly purchased, and then the first surface 101 and the second surface 102 of the base layer 10 are processed by chemical etching or laser etching, so that the roughness of the first surface 101 and the second surface 102 reaches 0.07μm (micrometer) to 0.3μm, and the first surface 101 and the second surface 102 are processed by corona treatment or plasma treatment, so that the dyne value of the first surface 101 and the second surface 102 is greater than 40mN / m (millinewton / meter), and then the treated base layer 10 is placed in the coating chamber for coating, and the coating layer 20 is sputtered or coated on the first surface 101 and the second surface 102 by magnetron sputtering or vacuum evaporation. During the coating process, the coating rate of the vacuum coating equipment is controlled so that the surface density of the coating layer 20 is 1g / cm 2 (g / cm2) to 20g / cm 2 In this way, the change in the roughness and dyne value of the first surface 101 and the second surface 102 can improve the adsorption and bonding ability of the base layer 10 to the coating layer 20, and the change in the surface density of the coating layer 20 can improve the tightness between the coating layer 20 and the base layer 10, thereby enhancing the bonding force between the base layer 10 and the coating layer 20. Compared with directly sputtering or plating the coating layer 20 on the base layer 10, the preparation method of the composite film of the present invention can improve the bonding force between the coating layer 20 and the base layer 10, increase the difficulty of peeling the coating layer 20 from the base layer 10, and thus extend the service life of the composite film.

[0040] Specifically, in the present invention, the roughness of the first surface 101 and the second surface 102 is detected by a surface roughness measuring instrument, the dyne value of the first surface 101 and the second surface 102 is detected by a dyne pen, and the surface density of the coating 20 is detected by X-ray fluorescence spectrometry (XRF) or X-ray reflectometry (XRR).

[0041] Furthermore, the first predetermined value R in this embodiment satisfies the relationship: 0.07μm≤R≤0.3μm, for example, 0.07μm, 0.09μm, 0.1μm, 0.12μm, 0.14μm, 0.16μm, 0.18μm, 0.2μm, 0.22μm, 0.24μm, 0.26μm, 0.28μm, 0.3μm and any value therebetween. Since the roughness is an unevenness with smaller spacing and tiny peaks and valleys, that is, there are tiny peaks and valleys on the first surface 101 and the second surface 102 of the substrate layer 10, at this time, when the roughness of the first surface 101 and the second surface 102 is less than 0.07μm, the height of the tiny peaks and valleys will be reduced, making the first surface 101 and the second surface 102 smooth, thereby reducing the adsorption and binding ability of the substrate layer 10; when the roughness of the first surface 101 and the second surface 102 is greater than 0.3μm, although the unevenness of the tiny peaks and valleys is increased, this will increase the resistance of the composite film. When the composite conductive film is used in a battery, the service life of the battery will be reduced.

[0042] Furthermore, the second predetermined value D in this embodiment satisfies the relationship: D>40mN / m, such as 42mN / m, 43mN / m, 45mN / m, 47mN / m, 50mN / m, etc. The dyne value refers to the value of the surface tension of the substrate layer 10 tested by a dyne pen. When the dyne value of the first surface 101 and the second surface 102 of the substrate layer 10 is greater than 40mN / m, the adsorption and binding ability of the substrate layer 10 will be improved, thereby improving the binding force between the substrate layer 10 and the coating 20; when the dyne value of the first surface 101 and the second surface 102 of the substrate layer 10 is less than 40mN / m, the coating 20 is difficult to sputter or plate on the surface of the substrate layer 10, and the coating 20 is easy to peel off from the substrate layer 10.

[0043] Furthermore, the third predetermined value ∑ in this embodiment satisfies the relationship: 1 g / cm 2 ≤∑≤20g / cm 2 , for example 1g / cm 2 , 2g / cm 2 , 4g / cm 2 , 6g / cm 2 , 8g / cm 2 、10g / cm 2 , 12g / cm 2 , 14g / cm 2 , 16g / cm 2 , 18g / cm 2 , 20g / cm 2Since the first surface 101 and the second surface 102 in the present invention are rough and uneven, when the coating 20 has a high density, it can be in close contact with the first surface 101 and the second surface 102. Therefore, when the surface density of the coating 20 is less than 1g / cm 2 When the surface density of the coating 20 is greater than 20 g / cm, the density of the coating 20 is reduced, thereby reducing the closeness between the coating 20 and the first surface 101 and the second surface 102, and reducing the bonding force between the coating 20 and the base layer 10 to a certain extent; when the surface density of the coating 20 is greater than 20 g / cm 2 When the composite membrane is used in a battery, the migration path of lithium ions in the battery will become longer. At this time, the internal resistance of the battery is also large, and congestion is likely to occur on the migration path of lithium ions, ultimately leading to a loss of battery capacity.

[0044] Furthermore, step S1 of this embodiment specifically includes the following steps:

[0045] S1.1: Processing the first surface 101 and the second surface 102 by chemical etching or laser etching so that the roughness of the first surface 101 and the second surface 102 reaches a first predetermined value R;

[0046] S1.2: The first surface 101 and the second surface 102 are treated by corona treatment or plasma treatment, so that the dyne values ​​of the first surface 101 and the second surface 102 reach a second predetermined value D.

[0047] Specifically, the chemical etching method can control the etching depth and has a fast etching speed; the laser etching method has high precision and a fast etching speed; the corona treatment method has the advantages of short processing time, fast speed, simple operation, and easy control; the plasma treatment method has the advantages of low production cost and high processing efficiency. When the chemical etching method or the laser etching method is used to process the first surface 101 and the second surface 102, the roughness of the first surface 101 and the second surface 102 can be quickly changed, which saves production time to a certain extent; when the corona treatment method or the plasma treatment method is used to process the first surface 101 and the second surface 102, due to the short processing time and high processing efficiency of the corona treatment method or the plasma treatment method, the change speed of the dyne value of the first surface 101 and the second surface 102 can be accelerated, which improves the production efficiency to a certain extent.

[0048] Further, in step S2, the vacuum coating equipment is turned on, and the coating rate is controlled to be 10 m / min to 100 m / min, for example, 10 m / min, 20 m / min, 40 m / min, 60 m / min, 80 m / min, 100 m / min and any value therebetween, and the coating layer 20 is prepared on the first surface 101 and the second surface 102 by magnetron sputtering; or,

[0049] In step S2, the vacuum coating equipment is turned on, and the coating rate is controlled to be 70 m / min to 100 m / min, for example, 70 m / min, 75 m / min, 80 m / min, 85 m / min, 90 m / min, 95 m / min, 100 m / min and any value therebetween, and the coating layer 20 is prepared on the first surface 101 and the second surface 102 by using a roller coating method; or,

[0050] In step S2, the vacuum coating equipment is turned on, and the coating rate is controlled to be 100 m / min to 300 m / min, for example, 100 m / min, 120 m / min, 140 m / min, 160 m / min, 180 m / min, 200 m / min, 220 m / min, 240 m / min, 260 m / min, 280 m / min, 300 m / min and any value therebetween, and the coating layer 20 is prepared on the first surface 101 and the second surface 102 by a suspended coating method.

[0051] Specifically, the present invention can use magnetron sputtering or vacuum evaporation to sputter or plate the coating 20 on the first surface 101 and the second surface 102 of the base layer 10. Among them, the magnetron sputtering method has the advantages of: having high energy, when the coating 20 is sputtered or plated on the first surface 101 and the second surface 102, it can improve the density of the coating 20 film surface, and can enhance the bonding force between the coating 20 and the base layer 10; the roller coating method and the suspension coating method mentioned in the present invention are both vacuum evaporation methods, and the advantages of the vacuum evaporation method are: simple film forming method, high film purity and density, and high coating efficiency.

[0052] Further, the base layer 10 in the present embodiment is made of one or more of polyethylene, polypropylene, ethylene-propylene copolymer, polyethylene terephthalate, polyethylene naphthalate, and poly(p-phenylene terephthalamide), acrylonitrile-butadiene-styrene copolymer, poly(p-phenylene terephthalamide), poly(propylene), polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber, and polycarbonate. When the base layer 10 is made of polyethylene, polypropylene, ethylene-propylene copolymer, polyethylene terephthalate, polyethylene naphthalate, and poly(p-phenylene terephthalamide), acrylonitrile-butadiene-styrene copolymer, poly(p-phenylene terephthalamide), poly(propylene), polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber, and polycarbonate, it can be mixed in any proportion, and the present invention is not specifically limited.

[0053] Specifically, polyethylene, polypropylene, ethylene propylene copolymer, polyethylene terephthalate, polyethylene naphthalate, poly(p-phenylene terephthalamide), acrylonitrile-butadiene-styrene copolymer, poly(p-phenylene terephthalamide), polypropylene, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber and polycarbonate have the advantages of light weight, good toughness and high impact strength, which are beneficial to the subsequent coating process and can improve the structural stability of the composite film.

[0054] Further, the coating 20 in this embodiment is made of one or more of copper, aluminum, copper alloy, aluminum alloy, nickel alloy, nickel, titanium alloy and titanium; or, the coating 20 in this embodiment is made of one or more of aluminum oxide and silicon nitride. That is to say, the coating 20 in the present invention can be a metal layer or a non-metal layer.

[0055] Specifically, when the coating 20 is made of a plurality of copper, aluminum, copper alloy, aluminum alloy, nickel alloy, nickel, titanium alloy and titanium, the proportions of copper, aluminum, copper alloy, aluminum alloy, nickel alloy, nickel, titanium alloy and titanium can be arbitrarily selected, and the present invention does not specifically limit them. Since copper, aluminum, copper alloy, aluminum alloy, nickel alloy, nickel, titanium alloy and titanium have good electrical conductivity and thermal conductivity, high chemical stability and good corrosion resistance, using them as the preparation material of the coating 20 can give full play to the excellent performance of the composite film and enhance the electrical conductivity of the composite film to a certain extent.

[0056] Specifically, when the coating 20 is made of multiple materials of aluminum oxide and silicon nitride, the ratio of aluminum oxide to silicon nitride can be arbitrarily selected, and the present invention does not specifically limit it. Since aluminum oxide and silicon nitride are wear-resistant, corrosion-resistant, high-temperature-resistant and have good adhesion, they are easy to combine with other functional layers and have extremely high thermal stability, thereby improving the bonding force between the base layer 10 and the coating 20.

[0057] On the other hand, an embodiment of the present invention further provides a composite membrane, which is prepared by the above-mentioned composite membrane preparation method, and therefore, the composite membrane includes all the technical effects of the above-mentioned composite membrane preparation method. Since the technical effects of the composite membrane preparation method have been described in detail above, they will not be repeated here.

[0058] Further, see Figure 1 As shown, the composite film in this embodiment includes a base layer 10 and a coating layer 20 disposed on a first surface 101 and a second surface 102 .

[0059] Further, in the present embodiment, the roughness R of the first surface 101 and the second surface 102 satisfies the relationship: 0.07 μm ≤ R ≤ 0.3 μm, for example, 0.07 μm, 0.09 μm, 0.1 μm, 0.12 μm, 0.14 μm, 0.16 μm, 0.18 μm, 0.2 μm, 0.22 μm, 0.24 μm, 0.26 μm, 0.28 μm, 0.3 μm and any value therebetween. In this way, the adsorption and bonding ability of the base layer 10 can be improved, thereby improving the bonding force between the base layer 10 and the coating 20, and effectively preventing the coating 20 from detaching from the surface of the base layer 10.

[0060] Furthermore, in this embodiment, the dyne values ​​D of the first surface 101 and the second surface 102 satisfy the relationship: D>40mN / m, such as 42mN / m, 43mN / m, 45mN / m, 47mN / m, 50mN / m, etc. In this way, the adsorption and bonding ability of the base layer 10 can be improved, thereby improving the bonding force between the base layer 10 and the coating layer 20, and effectively preventing the coating layer 20 from detaching from the surface of the base layer 10.

[0061] Furthermore, the surface density ∑ of the coating 20 in this embodiment satisfies the relationship: 1 g / cm 2 ≤∑≤20g / cm 2 , for example 1g / cm 2 , 2g / cm 2 , 4g / cm 2 , 6g / cm 2 , 8g / cm 2 , 10g / cm 2 , 12g / cm 2 , 14g / cm 2 , 16g / cm 2 , 18g / cm 2 , 20g / cm 2 In this way, the coating 20 can be ensured to have a good density, thereby improving the closeness of the contact between the coating 20 and the base layer 10, and improving the bonding force between the coating 20 and the base layer 10 to a certain extent.

[0062] It should be noted that the thickness direction of the composite film in the present invention is Figure 1 The direction indicated by the letter X.

[0063] Further, along the thickness direction of the composite film, the thickness of the base layer 10 is 3 μm to 8 μm, for example, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm and any value therebetween. When the thickness of the base layer 10 is less than 3 μm, the base layer 10 is easily damaged during the stretching process, which is not conducive to the sputtering or plating of the subsequent coating layer 20; when the thickness of the base layer 10 is greater than 8 μm, the overall weight of the current collector is increased, thereby increasing the production cost of the current collector.

[0064] Further, in the present embodiment, along the thickness direction of the composite film, the thickness of the coating 20 is 50nm to 2000nm, for example, 50nm, 100nm, 200nm, 400nm, 600nm, 800nm, 1000nm, 1200nm, 1400nm, 1600nm, 1800nm, 2000nm and any value therebetween. When the thickness of the coating 20 is less than 50nm, it is not conducive to sputtering or plating the coating 20 on the base layer 10. If the thickness of the coating 20 is greater than 2000nm, the weight of the coating 20 will be increased, thereby increasing the weight of the composite conductive film as a whole, thereby increasing the production cost of the composite conductive film.

[0065] The composite membrane of the present invention will be described in detail below in conjunction with specific embodiments.

[0066] Example 1

[0067] See also Figure 1 As shown, the composite film in this embodiment includes a base layer 10 and a coating layer 20 disposed on a first surface 101 and a second surface 102 .

[0068] When the composite mold is actually prepared, a base layer 10 is obtained, and a first surface 101 and a second surface 102 of the base layer 10 are treated by chemical etching or laser etching to make the roughness of the first surface 101 and the second surface 102 0.07 μm, and then a corona treatment method or a plasma treatment method is used to treat the first surface 101 and the second surface 102 to make the dyne value of the first surface 101 and the second surface 102 45 mN / m, and then the base layer 10 is placed in a coating chamber of a vacuum coating device, and a magnetron sputtering method is used to prepare a surface density of 1 g / cm on the first surface 101 and the second surface 102. 2 The coating layer 20 is obtained. Figure 1 Composite membrane with the structure shown.

[0069] Example 2

[0070] Different from Example 1, the roughness of the first surface 101 and the second surface 102 in this embodiment is 0.3 μm, the dyne value of the first surface 101 and the second surface 102 is 47 mN / m, and the surface density of the coating 20 is 20 g / cm 2 .

[0071] Example 3

[0072] Different from Example 1, the roughness of the first surface 101 and the second surface 102 in this embodiment is 0.2 μm, the dyne value of the first surface 101 and the second surface 102 is 70 mN / m, and the surface density of the coating 20 is 10 g / cm 2 .

[0073] Comparative Example 1

[0074] The comparative example provides a composite film, which is different from the embodiment 1 in that the roughness of the first surface 101 and the second surface 102 is 0.05 μm.

[0075] Comparative Example 2

[0076] The composite film is different from Example 1 in that the roughness of the first surface 101 and the second surface 102 is 0.32 μm.

[0077] Comparative Example 3

[0078] The composite film is different from Example 1 in that the dyne values ​​of the first surface 101 and the second surface 102 are 34 mN / m.

[0079] Comparative Example 4

[0080] The difference between the composite film and Example 1 is that the surface density of the coating layer 20 is 0.9 g / cm 2 .

[0081] Comparative Example 5

[0082] The difference between the composite film and Example 1 is that the surface density of the coating layer 20 is 21 g / cm 2 .

[0083] Table 1 Test of bonding strength between substrate and coating

[0084]

[0085]

[0086] After the composite film of the present invention is prepared, the bonding force between the base layer 10 and the coating 20 is tested by means of adhesive tape. Specifically, after the coating 20 is sputtered or plated on the surface of the base layer 10, the adhesive tape is first pasted on the coating 20, and then the adhesive tape is pulled with the same force using a tensile testing machine until the adhesive tape is separated from the coating 20. If there is no metal material or non-metal material adhering to the coating 20 on the adhesive tape, it can be considered that the coating 20 is not separated from the base layer 10, and at this time, the bonding force between the base layer 10 and the coating 20 is improved; if there is a metal material or non-metal material adhering to the coating 20 on the adhesive tape, it can be considered that the bonding force between the coating 20 and the base layer 10 is weak, and the coating 20 is easy to fall off from the base layer 10.

[0087] As shown in Table 1, when the roughness of the first surface 101 and the second surface 102 of the composite film of the present invention is 0.07 μm to 0.3 μm, the dyne value of the first surface 101 and the second surface 102 is greater than 40 mN / m, and the surface density of the coating 20 is 1 g / cm 2 Up to 20g / cm 2 When the adhesive tape is used, there is no metal material or non-metal material for bonding the coating 20 , so that the tightness between the coating 20 and the base layer 10 can be improved, thereby enhancing the bonding force between the base layer 10 and the coating 20 .

[0088] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0089] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0090] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a composite film, characterized in that: include: Step S1: obtaining a base layer (10), and processing a first surface (101) and a second surface (102) of the base layer (10) so that the roughness of the first surface (101) and the second surface (102) reaches a first predetermined value R, and the dyne value of the first surface (101) and the second surface (102) reaches a second predetermined value D; Step S2: placing the base layer (10) in a coating chamber of a vacuum coating device, and controlling the coating rate of the vacuum coating device to prepare a coating (20) having a surface density reaching a third predetermined value ∑ on the first surface (101) and the second surface (102).

2. The method for preparing a composite film according to claim 1, characterized in that: The first predetermined value R satisfies the relationship: 0.07 μm≤R≤0.3 μm.

3. The method for preparing a composite film according to claim 1, characterized in that: The second predetermined value D satisfies the relationship: D>40mN / m.

4. The method for preparing a composite membrane according to any one of claims 1 to 3, characterized in that: The third predetermined value ∑ satisfies the relationship: 1g / cm 2 ≤∑≤20g / cm 2 .

5. The method for preparing a composite film according to claim 4, characterized in that: The step S1 specifically includes the following steps: S1.1: Processing the first surface (101) and the second surface (102) by chemical etching or laser etching, so that the roughness of the first surface (101) and the second surface (102) reaches the first predetermined value R; S1.2: The first surface (101) and the second surface (102) are treated by corona treatment or plasma treatment so that the dyne values ​​of the first surface (101) and the second surface (102) reach the second predetermined value D.

6. The method for preparing a composite membrane according to claim 1, 2, 3 or 5, characterized in that: In the step S2, the vacuum coating equipment is turned on, and the coating rate is controlled to be 10 m / min to 100 m / min, and the coating layer (20) is prepared on the first surface (101) and the second surface (102) by magnetron sputtering; or, In the step S2, the vacuum coating equipment is turned on, and the coating rate is controlled to be 70 m / min to 100 m / min, and the coating layer (20) is prepared on the first surface (101) and the second surface (102) by a roller coating method; or, In the step S2, the vacuum coating equipment is turned on, and the coating rate is controlled to be 100 m / min to 300 m / min, and the coating layer (20) is prepared on the first surface (101) and the second surface (102) by a suspension coating method.

7. The method for preparing a composite membrane according to claim 1, 2, 3 or 5, characterized in that: The base layer (10) is made of one or more of polyethylene, polypropylene, ethylene-propylene copolymer, polyethylene terephthalate, polyethylene naphthalate, poly(p-phenylene terephthalamide), acrylonitrile-butadiene-styrene copolymer, poly(p-phenylene terephthalamide), polypropylene, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber and polycarbonate.

8. The method for preparing a composite membrane according to claim 1, characterized in that: The coating (20) is made of one or more of copper, aluminum, copper alloy, aluminum alloy, nickel alloy, nickel, titanium alloy and titanium; or, The coating (20) is made of one or more of aluminum oxide and silicon nitride.

9. A composite membrane, characterized in that The composite film is prepared by the composite film preparation method according to any one of claims 1 to 8, and the composite film comprises the base layer (10) and the coating layer (20) arranged on the first surface (101) and the second surface (102).

10. The composite membrane according to claim 9, characterized in that The roughness R of the first surface (101) and the second surface (102) satisfies the relationship: 0.07 μm ≤ R ≤ 0.3 μm; and / or, The dyne values ​​D of the first surface (101) and the second surface (102) satisfy the relationship: D>40mN / m; and / or, The surface density ∑ of the coating (20) satisfies the relationship: 1 g / cm 2 ≤∑≤20g / cm 2 .

11. The composite membrane according to claim 9, characterized in that Along the thickness direction of the composite film, the thickness of the base layer (10) is 3 μm to 8 μm; and / or, Along the thickness direction of the composite film, the thickness of the coating layer (20) is 50 nm to 2000 nm.

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