Composite copper foil film and preparation method thereof

Abstract

The present invention discloses a composite copper foil film and a method for preparing the same. The composite copper foil film comprises a substrate layer and conductive layers attached to both sides of the substrate layer, wherein the conductive layers comprise, from the inside out, a metallic copper sputtering layer, a metallic copper electroplating layer, and a protective layer. The preparation method comprises the following steps: forming the substrate layer from a polyester film to which a polyester functional masterbatch is added; corona treating both surfaces of the substrate layer to form a corona layer; forming a barrier layer on the outer side of the corona layer; and forming the conductive layer on the outer side of the barrier layer. The composite copper foil film prepared in this application is obtained by combining a vacuum sputtering process with a water electroplating process, achieving excellent electrical performance and adhesion without damaging the surface structure of the substrate layer.

Description

Technical Field

[0001] The present application relates to a current collector for conducting electricity in a lithium-ion battery, and in particular to a composite copper foil film that can be used as a negative electrode current collector for a lithium-ion battery and a preparation method thereof. Background Art

[0002] The current collector in a lithium-ion battery is composed of a conductive metal foil film. Its main function is to carry the electrode materials of the positive and negative electrodes, while collecting current and conducting electrons. Aluminum foil is commonly used as the positive electrode current collector, and copper foil is commonly used as the negative electrode current collector. The aluminum and copper foils used as current collectors are mainly used for conductivity and do not participate in active reactions. Therefore, under the demand for increasing the energy density of the battery, their thickness has been reduced to the strength limit, and there is no room for further thinning. By drawing on the composite metal films in the existing technology, composite metal films have emerged that use non-metallic insulating materials as the substrate and conductive layers formed on both sides.

[0003] CN 114481034 A discloses a method, apparatus, and system for preparing a composite metal foil. The apparatus comprises: primary and secondary double-sided coating modules spaced apart. The primary double-sided coating module comprises: a first evaporation column and a second evaporation column disposed opposite each other, and a roll-off roller, a first evaporation source, a first set of rollers, a second evaporation source, and a second set of rollers disposed sequentially from bottom to top on opposing surfaces of the first and second evaporation columns. The secondary double-sided coating module comprises: a third evaporation column, and a first set of cooling rollers, a third evaporation source, a second set of cooling rollers, a fourth evaporation source, and a roll-off roller disposed sequentially from top to bottom on the third evaporation column. This prior art achieves primary double-sided coating by disposing two evaporation sources and their associated roller systems from bottom to top on opposing surfaces of the first and second evaporation columns, and secondary double-sided coating by disposing two evaporation sources and their associated roller systems from top to bottom on the third evaporation column, thereby improving site utilization and film production efficiency.

[0004] During the preparation process of the composite metal foil of the prior art, the target material needs to be evaporated into a gas at high temperature and then attached to the surface of the non-metallic substrate layer. The higher the evaporation temperature of the target material, the more likely the substrate layer will suffer from defects such as melting or burning. Therefore, the prior art generally produces composite aluminum foil by vapor deposition, and rarely produces composite copper foil by vapor deposition because copper has a higher evaporation temperature. The higher the evaporation temperature of the target material, the faster the substrate layer needs to be operated, and the thinner the metal layer formed by vapor deposition will be. The conductive properties of the composite metal foil will also deteriorate accordingly, making it unsuitable for use as a current collector for lithium-ion batteries. Therefore, the composite aluminum foil prepared by existing vapor deposition can usually only be used as food packaging material. Moreover, because the metal layer formed by vapor deposition has poor adhesion and is very easy to fall off, even if it is used as a food packaging material, a protective film needs to be added to the surface of the metal layer to prevent the detached metal from contaminating the food.

[0005] Another reason why the metal layer of composite aluminum foil easily falls off is that the surface structure of the non-metallic substrate layer used to support the metal layer is uneven, resulting in insufficient adhesion of the metal layer to the substrate layer. To mitigate the impact of long-term high-temperature baking on the surface properties of the substrate layer, the metal layer needs to be gradually stacked at intervals. The various structural and performance defects of the substrate layer are gradually amplified by the stacked metal layers. Therefore, existing composite metal foils and their preparation processes are difficult to apply to the production of composite copper foil films that can be used as current collectors. Summary of the Invention

[0006] The technical problem to be solved by the present application is to provide a composite copper foil film and a preparation method thereof, so as to reduce or avoid the above-mentioned problems.

[0007] In order to solve the above technical problems, the present application proposes a composite copper foil film, which is composed of a substrate layer and a conductive layer attached to both sides of the substrate layer, wherein the conductive layer includes a metal copper sputtering layer, a metal copper electroplating layer and a protective layer from the inside to the outside; wherein the metal copper sputtering layer is a layer of metal copper with a thickness of 5-15nm formed on the surfaces of both sides of the substrate layer by a vacuum sputtering process, the metal copper electroplating layer is a layer of metal copper with a thickness of 100-500nm grown on the outer surface of the metal copper sputtering layer by a water electroplating process, and the protective layer is a dense protective layer formed after passivation treatment on the outer surface of the metal copper electroplating layer; the protective layer is a 5-15nm metal chromium protective layer formed by an electroplating process.

[0008] Preferably, the thickness of the metal copper sputtering layer is 5-8 nm, the thickness of the metal copper electroplating layer is 300-400 nm, and the thickness of the metal chromium protective layer is 5-8 nm.

[0009] Preferably, a barrier layer composed of silicon dioxide with a thickness of 2-3 nm is formed by sputtering on the outer side of the substrate layer between the conductive layer and the substrate layer.

[0010] Preferably, a corona layer with a thickness of 1-2 nm is formed on the surface of the substrate layer, and the barrier layer is formed on the outer side of the corona layer.

[0011] Preferably, the substrate layer is made of a polyester film to which a polyester functional masterbatch is added, and the polyester film is a single-layer polyester film containing 5 to 20 wt% of the polyester functional masterbatch, or a three-layer polyester film comprising layer A, layer B, and layer C, wherein layer A and layer C contain 5 to 20 wt% of the polyester functional masterbatch, wherein the polyester functional masterbatch is prepared from raw materials including the following parts by weight: 30-50 parts by weight of polyisophthalamide, 1-3 parts by weight of cobalt neodecanoate, 3-5 parts by weight of butylated hydroxytoluene, 5 to 10 parts by weight of 1,4-diiodobenzene, 20 to 30 parts by weight of silica, and 50-100 parts by weight of PET.

[0012] The present application further proposes a method for preparing a composite copper foil film, which is composed of a substrate layer and a conductive layer attached to both sides of the substrate layer. The preparation method includes the following steps: making the substrate layer from a polyester film to which a polyester functional masterbatch is added; performing corona treatment on both sides of the substrate layer to form a corona layer; forming a barrier layer on the outside of the corona layer; and forming the conductive layer on the outside of the barrier layer.

[0013] Preferably, the polyester film constituting the substrate layer is a single-layer polyester film containing 5-20 wt% of a polyester functional masterbatch, and the polyester film is prepared by the following steps: the following components in a weight ratio: 80-95 wt% of a PET resin and 5-20 wt% of a polyester functional masterbatch are measured by an electronic scale, and the mixture is mixed in a mixing bin to form a mixture; the mixture is then fed into a vented twin-screw extruder, and the temperature of the twin-screw extruder is adjusted to 270° C. to 280° C. After the material is melted in the extruder, it is filtered and extruded into a thick sheet; the thickness and profile of the thick sheet can be adjusted by The extruder extrusion rate, casting roller speed, and die opening are adjusted; the thick sheet is preheated at a temperature of 50°C to 90°C, enters an infrared heating zone of 300°C to 500°C, and is longitudinally stretched at a linear speed of 40 to 150 m / min with a longitudinal stretching ratio of 4.0 to obtain a stretched sheet; the stretched sheet is preheated at a temperature of 90°C to 120°C, and transversely stretched at a temperature of 100°C to 160°C with a transverse stretching ratio of 3.8; thereafter, the sheet is shaped at a temperature of 160°C to 240°C, and then cooled at a temperature of 100°C to 50°C to obtain a polyester film for composite copper foil film.

[0014] Preferably, the polyester film constituting the substrate layer is a three-layer polyester film comprising A layer, B layer and C layer, wherein the A layer and the C layer contain 5-20wt% of polyester functional masterbatch, and the polyester film is prepared by the following steps: the following components in a weight ratio: 80-95wt% of PET resin and 5-20wt% of polyester functional masterbatch are measured by an electronic scale respectively, and the mixed materials are put into a mixing bin for mixing to form a mixed material; the mixed material then enters a venting twin-screw extruder E; 100% of the PET resin is put into a pre-crystallizer and pre-crystallized at a temperature of 160°C for 15 minutes, and then the PET material enters a drying tower and is dried at a temperature of 160°C for 6 hours, and then enters a single-screw extruder F; the temperature of the twin-screw extruders E and F is adjusted to 270°C to 280°C; after the material is melted in the two extruders, it is passed through a pre-crystallizer. The method comprises the following steps: filtering, using the material extruded by the twin-screw extruder E as the surface A layer and the C layer, and the material extruded by the single-screw extruder F as the middle B layer, and forming a three-layer composite thick sheet through a multi-layer co-extrusion process; the thickness and profile of the thick sheet can be adjusted by the extruder extrusion output, the casting roller speed, and the die head opening; preheating the thick sheet at a temperature of 50°C to 90°C, entering an infrared heating zone at a temperature of 300°C to 500°C, and longitudinally stretching it at a linear speed of 40 to 150 m / min with a longitudinal stretching ratio of 4.0 to obtain a stretched sheet; preheating the stretched sheet at a temperature of 90°C to 120°C, and transversely stretching it at a temperature of 100°C to 160°C with a transverse stretching ratio of 3.8; then shaping it at a temperature of 160°C to 240°C, and then cooling it at a temperature of 100°C to 50°C to obtain the polyester film with the three-layer structure.

[0015] Preferably, the preparation method further includes the steps of preparing the polyester functional masterbatch: at room temperature, adding 50-100 parts by weight of powdered PET, 20-30 parts by weight of nano-silica, 30-50 parts by weight of powdered polyisophthalamide, 1-3 parts by weight of powdered cobalt neodecanoate, 3-5 parts by weight of powdered butylated hydroxytoluene, and 5-10 parts by weight of powdered 1,4-diiodobenzene into a high-speed mixer for pre-dispersion and mixing at a speed of 1500-2000 rpm for 30-60 minutes to form a mixture; then melt-extruding through a twin-screw extruder, followed by water-cooling and granulation or slicing to obtain the polyester functional masterbatch.

[0016] Preferably, the conductive layer includes, from the inside to the outside, a metal copper sputtering layer, a metal copper electroplating layer and a protective layer; wherein the steps of forming the conductive layer include: forming a metal copper sputtering layer on the outside of the barrier layer by a vacuum sputtering process; growing a metal copper electroplating layer on the outer surface of the metal copper sputtering layer by a water electroplating process; and forming a protective layer on the outer surface of the metal copper electroplating layer by an electroplating process.

[0017] The polyester film that constitutes the current collector substrate of this application is added with a polyester functional masterbatch. The resulting polyester film has properties such as low porosity, low water absorption, and low oxygen permeability. The conductive layer formed on the outside does not show obvious crack expansion, and the structural consistency on both sides is better. This application prepares the composite copper foil film by combining a vacuum sputtering process and a water electroplating process, which can achieve excellent electrical performance and adhesion without destroying the surface structure of the substrate layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The following drawings are only intended to illustrate and explain the present application and are not intended to limit the scope of the present application.

[0019] Figure 1 Shown is a schematic structural diagram of a composite copper foil film according to a specific embodiment of the present application.

[0020] Figure 2 Shown is a schematic structural diagram of a composite copper foil film according to another specific embodiment of the present application.

[0021] Figure 3 Shown is a schematic structural diagram of a composite copper foil film according to another specific embodiment of the present application. DETAILED DESCRIPTION

[0022] In order to have a clearer understanding of the technical features, objectives and effects of this application, the specific implementation of this application is now described with reference to the accompanying drawings, wherein the same components are marked with the same reference numerals.

[0023] As shown in the figure, the present invention proposes a composite copper foil film that can be used as a negative electrode current collector for lithium-ion batteries. The composite copper foil film is composed of a substrate layer 1 and a conductive layer 2 attached to both sides of the substrate layer 1. The conductive layer 2 is primarily composed of metallic copper. As previously mentioned, due to the high evaporation temperature of metallic copper, if it is deposited on the surface of the polymer substrate layer 1 by evaporation, the uniformity of the substrate layer 1's surface structure will be destroyed. It is also difficult to achieve the thickness required for sufficient electrical performance. Moreover, the thicker the stack, the more likely it is to shed and powder, making it unsuitable for use as a negative electrode current collector.

[0024] In view of this, the present application proposes a composite copper foil film, wherein the conductive layer 2 adopts a multi-layer conductive structure. In the specific embodiment shown in the figure, the conductive layer 2 includes, from the inside to the outside, a metal copper sputtering layer 21, a metal copper electroplating layer 22, and a protective layer. The metal copper sputtering layer 21 is a layer of metal copper with a thickness of 5-15 nm formed on both sides of the substrate layer 1 using a vacuum sputtering process. The metal copper electroplating layer 22 is a layer of metal copper with a thickness of 100-500 nm grown on the outer surface of the metal copper sputtering layer 21 using a water electroplating process. The protective layer is a dense protective layer formed by passivating the outer surface of the metal copper electroplating layer 22 through electroplating or chemical etching. Preferably, the protective layer is a 5-15 nm metal chromium protective layer 23 formed through electroplating. More preferably, the thickness of the metal copper sputtering layer 21 is 5-8 nm, the thickness of the metal copper electroplating layer 22 is 300-400 nm, and the thickness of the metal chromium protective layer 23 is 5-8 nm.

[0025] In the composite copper foil film of the present application, the density and adhesion of the metal copper sputtering layer formed by vacuum sputtering are far superior to those of the evaporation process, and because the required thickness is very thin, the operation speed of the substrate layer can be very fast, which basically eliminates the possibility of defects such as melting or scalding in the substrate layer. Although the thickness of the metal copper sputtering layer is very thin, it can provide basic conductive properties, and thus a thicker metal copper layer can be further grown on its surface by water electroplating. Through the combination of the vacuum sputtering process and the water electroplating process, the present application can obtain excellent electrical properties and adhesion without destroying the surface structure of the substrate layer, which will be further explained later.

[0026] In addition, in order to avoid the problem of insufficient adhesion of the metal copper layer due to the uneven surface structure of the substrate layer, the present application also proposes an improved substrate layer 1. In a specific embodiment of the present application, the substrate layer 1 of the present application is made of a polyester film with a polyester functional masterbatch added thereto. The substrate layer 1 can be a single-layer polyester film with a polyester functional masterbatch added thereto ( Figure 1 ), or a polyester film having a three-layer structure including layer A, layer B, and layer C with the polyester functional masterbatch added to the surface ( Figure 2 ).

[0027] The polyester referred to in the present invention refers to a polyester formed from one or more polycarboxylic acids selected from dibasic acids and their ester-forming derivatives, and one or more polyols selected from diols; or a polyester formed from hydroxycarboxylic acids and their ester-forming derivatives; or a polyester formed from cyclic esters. The production of polyester can be carried out according to conventional methods. For example, taking the preparation of PET as an example, it can be obtained by the following methods: esterification of terephthalic acid and ethylene glycol followed by polycondensation; or by transesterification of an alkyl ester of terephthalic acid, such as dimethyl terephthalate, with ethylene glycol followed by polycondensation. The polyester of the present invention is preferably PET.

[0028] In a specific embodiment, the polyester film constituting the substrate layer 1 is a single-layer polyester film containing 5 to 20 wt% of a polyester functional masterbatch, or a three-layer polyester film comprising layer A, layer B, and layer C, wherein layer A and layer C contain 5 to 20 wt% of a polyester functional masterbatch, and the polyester functional masterbatch is prepared from raw materials including the following parts by weight: 30-50 parts by weight of polyisophthalamide, 1-3 parts by weight of cobalt neodecanoate, 3-5 parts by weight of dibutylhydroxytoluene, 5 to 10 parts by weight of 1,4-diiodobenzene, 20 to 30 parts by weight of silica, and 50-100 parts by weight of PET.

[0029] The polyester functional masterbatch of the present invention can be prepared in the form of pellets or slices and added to ordinary polyester during the production of polyester film to produce the substrate layer 1 of the present invention. For example, 80-95 wt% of polyester without other ingredients can be melt-blended with 5-20 wt% of the polyester functional masterbatch of the present invention, and then a single-layer substrate layer 1 can be produced through a stretching process, or the surface structure of the substrate layer 1 of the present invention can be obtained through a multi-layer co-extrusion process.

[0030] The various raw material components of the polyester functional masterbatch of the present invention can be uniformly mixed in the form of granules, and then extruded and granulated using equipment such as an extruder to obtain the polyester functional masterbatch of the present invention.

[0031] In a specific embodiment, 50-100 parts by weight of powdered PET, 20-30 parts by weight of nano-silicon dioxide, 30-50 parts by weight of powdered polyisophthalamide, 1-3 parts by weight of powdered cobalt neodecanoate, 3-5 parts by weight of powdered butylated hydroxytoluene, and 5-10 parts by weight of powdered 1,4-diiodobenzene are added to a high-speed mixer at room temperature for pre-dispersion and mixing at a speed of 1500-2000 rpm for 30-60 minutes to form a mixture. The mixture is then melt-extruded through a twin-screw extruder, and then water-cooled for granulation or slicing to obtain the polyester functional masterbatch.

[0032] In another specific embodiment, for example, after preparing the polyester functional masterbatch slices, 5 to 20 wt% of the polyester functional masterbatch is taken and added to 80 to 95 wt% of PET particles and evenly mixed. The two are melt-blended and finally a single-layer substrate layer 1 is obtained through a stretching process, or a surface structure of a three-layer substrate layer 1 is obtained through a multi-layer co-extrusion process.

[0033] The following is an example of a single-layer polyester film to further illustrate the preparation method of the polyester film for composite copper foil film of the present invention. The preparation method of the polyester film for composite copper foil film of the present invention comprises the following steps:

[0034] The following components in weight ratio: 80-95 wt% of PET resin and 5-20 wt% of polyester functional masterbatch are measured by electronic scale respectively and put into a mixing bin for mixing to prepare a mixture.

[0035] The mixed material then enters a venting twin-screw extruder, and the temperature of the twin-screw extruder is adjusted to 270°C to 280°C.

[0036] After the material is melted in the extruder, it is filtered and extruded into thick sheets. The thickness and profile of the thick sheets can be adjusted by adjusting the extruder output, the speed of the casting roller, and the opening of the die.

[0037] The thick sheet is preheated at 50°C to 90°C, placed in an infrared heating zone at 300°C to 500°C, and longitudinally stretched at a line speed of 40 to 150 m / min with a longitudinal stretching ratio of 4.0 to obtain a stretched sheet.

[0038] The stretched sheet is preheated at 90°C to 120°C, stretched transversely at 100°C to 160°C, and stretched at a transverse stretching ratio of 3.8. It is then shaped at 160°C to 240°C, and then cooled at 100°C to 50°C to obtain a polyester film for composite copper foil.

[0039] The thickness of the prepared polyester film is 6-10 μm.

[0040] The following is an example of a three-layer polyester film to further illustrate the preparation method of the polyester film for composite copper foil film of the present invention. The preparation method of the polyester film for composite copper foil film of the present invention comprises the following steps:

[0041] The following components in weight ratio: 80-95 wt% of PET resin and 5-20 wt% of polyester functional masterbatch are measured by electronic scale respectively and put into a mixing bin for mixing to prepare a mixture.

[0042] The mixed material then enters the vented twin-screw extruder E.

[0043] 100% PET resin was put into the pre-crystallizer and pre-crystallized at 160°C for 15 minutes. The PET material then entered the drying tower and was dried at 160°C for 6 hours before entering the single-screw extruder F.

[0044] Adjust the temperature of twin-screw extruders E and F to 270°C to 280°C.

[0045] After the materials are melted in two extruders and filtered, the material extruded from twin-screw extruder E is used as the surface layers A and C, and the material extruded from single-screw extruder F is used as the middle layer B. Through a multi-layer co-extrusion process, a three-layer composite slab is produced. The thickness and profile of the slab can be adjusted by adjusting the extruder output, casting roller speed, and die opening.

[0046] The thick sheet is preheated at 50°C to 90°C, placed in an infrared heating zone at 300°C to 500°C, and longitudinally stretched at a line speed of 40 to 150 m / min with a longitudinal stretching ratio of 4.0 to obtain a stretched sheet.

[0047] The stretched sheet is preheated at 90°C to 120°C, stretched transversely at 100°C to 160°C with a transverse stretch ratio of 3.8, then shaped at 160°C to 240°C, and cooled at 100°C to 50°C to obtain the three-layer polyester film.

[0048] The thickness of the prepared polyester film is 6-10 μm, wherein the thickness of layer A is 1-2 μm, the thickness of layer B is 2-8 μm, and the thickness of layer C is 1-2 μm.

[0049] Examples 1-5

[0050] According to the weight ratio of the raw materials in the table below, polyester functional masterbatch chips were prepared respectively, and then ordinary PET resin was added to prepare a single-layer polyester film for composite copper foil film.

[0051] Example 1 Example 2 Example 3 Example 4 Example 5 Poly(m-xylylene diamide) 30 35 40 45 50 Cobalt neodecanoate 1 1.5 2 2.5 3 Butylated hydroxytoluene 3 3.5 4 4.5 5 1,4-Diiodobenzene 5 7 7.5 8 10 Silicon dioxide 20 22 25 27 30 PET 50 65 75 85 100 Amount of slices for preparing a single substrate layer 5wt% 10wt% 13wt% 15wt% 20wt% Substrate layer thickness μm 6 7 8 9 10

[0052] Comparative Examples 6-10

[0053] In the same manner as in the above example, a polyester film for comparison was prepared according to the weight ratio of the raw materials shown in the following table.

[0054] Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Poly(m-xylylene diamide) 0 35 40 45 50 Cobalt neodecanoate 1 0 2 2.5 3 Butylated hydroxytoluene 3 3.5 0 4.5 5 1,4-Diiodobenzene 5 7 7.5 0 10 Silicon dioxide 20 22 25 27 0 PET 80 66.5 79 93 130 Amount of slices for preparing a single substrate layer 5wt% 10wt% 13wt% 15wt% 20wt% Substrate layer thickness μm 6 7 8 9 10

[0055] The performance parameters of each polyester film were tested and prepared respectively, and an 8μm thick film prepared from pure PET without adding any functional masterbatch was compared. The performance parameters are shown in the following table.

[0056]

[0057] Metal copper sputtering layers were formed on both sides of the polyester film described in the above table by a vacuum sputtering process. The thickness of the metal copper layers on both sides by vacuum sputtering was controlled to be 5 nm. The surface crack parameters of the prepared films were tested.

[0058]

[0059]

[0060] It can be seen from the performance parameters of the above-mentioned film layer and the cracks in the metal plating layer that the polyester film prepared by adding the polyester functional masterbatch of the present application has greatly improved properties such as porosity, water absorption, and oxygen permeability, and no obvious crack expansion is observed after the metal copper conductive layer is formed.

[0061] Furthermore, the resistivity difference of the metal copper sputtered layers on both sides of the polyester film shown in the above table was tested, as shown in the following table.

[0062]

[0063] The resistivity difference of the metal copper sputtering layer formed on the polyester film prepared by adding the polyester functional masterbatch of the present application is significantly smaller than that of the film without adding the functional masterbatch, indicating that the structure on both sides has better consistency.

[0064] Furthermore, since this application requires first forming a metallic copper sputtering layer 21 on the surface of the substrate layer 1, the substrate layer 1 must be operated at a relatively low temperature during sputtering. Although the improved polyester film of the substrate layer 1 has excellent properties such as porosity, water absorption, and oxygen permeability, it is still necessary to prevent the problem of water absorption on the polyester film surface at low temperatures and subsequent release of water during sputtering, which may interfere with the vacuum level.

[0065] Therefore, in a specific embodiment, in order to avoid the problem of moisture absorption and release of the substrate layer 1 during sputtering, a barrier layer 11 is sputtered on the outer side of the substrate layer 1 between the conductive layer 2 and the substrate layer 1 to improve the performance of the conductive layer 2. Figure 3 Specifically, a barrier layer 11 composed of 2-3 nm silicon dioxide can be deposited on both sides of the substrate layer 1 by using a dual-rotating cathode and medium-frequency reactive magnetron sputtering method to form a coating and isolation on the surface of the substrate layer 1 and form a hydrophobic structure on the surface of the substrate layer 1.

[0066] Furthermore, since the barrier layer 11 is very thin, in order to improve the adhesion of the barrier layer 11 to the surface of the substrate layer 1, the surface of the substrate layer 1 is preferably subjected to a corona treatment before the barrier layer 11 is sputtered to form a corona layer 10 with a thickness of 1-2 nm. The barrier layer 11 is formed on the outside of the corona layer 10. Corona treatment is an existing technology. Its basic principle is to use high-frequency and high-voltage corona discharge on the surface of the treated plastic to roughen the surface of the substrate layer 1, thereby increasing the adhesion of the substrate layer 1 to the barrier layer 11.

[0067] The preparation method of the composite copper foil film of the present application is further described below.

[0068] As previously described, the composite copper foil film of the present application is composed of a substrate layer and conductive layers attached to both sides of the substrate layer. Therefore, the method for preparing the composite copper foil film of the present application includes the following steps: First, a substrate layer is formed from a polyester film to which a polyester functional masterbatch has been added. The steps for preparing the substrate layer have been described in detail previously and will not be repeated here.

[0069] Then, corona treatment is performed on both sides of the substrate layer to form a corona layer; then, a barrier layer is formed on the outer side of the corona layer; and finally, the conductive layer is formed on the outer side of the barrier layer.

[0070] Furthermore, as previously mentioned, the conductive layer comprises, from the inside out, a metal copper sputtering layer, a metal copper electroplating layer, and a protective layer. Therefore, the steps of forming the conductive layer include: forming the metal copper sputtering layer on the outside of the barrier layer using a vacuum sputtering process; growing a metal copper electroplating layer on the outer surface of the metal copper sputtering layer using a water electroplating process; and forming a protective layer on the outer surface of the metal copper electroplating layer using an electroplating process.

[0071] The polyester film prepared in Examples 1-5 was used as the substrate layer, and was subjected to corona treatment, sputtering of a barrier layer, sputtering of a metal copper sputtering layer, electroplating of a metal copper electroplating layer, and electroplating of a protective layer to prepare a composite copper foil film with the following parameters.

[0072]

[0073]

[0074] It can be seen from the measured parameters that the composite copper foil film of the present application has excellent electrical properties, and the conductive layer has extremely strong adhesion, and the conductive layer will hardly peel off during normal use.

[0075] Those skilled in the art should understand that although this application is described in terms of multiple embodiments, not each embodiment contains only one independent technical solution. This description is only for the sake of clarity. Those skilled in the art should understand the description as a whole and understand the scope of protection of this application by considering the technical solutions involved in each embodiment as being combinable into different embodiments.

[0076] The above description is only an illustrative embodiment of the present application and is not intended to limit the scope of the present application. Any equivalent changes, modifications and combinations made by any person skilled in the art without departing from the concept and principle of the present application shall fall within the scope of protection of the present application.

Claims

1. A composite copper foil film, comprising a substrate layer and conductive layers attached to both sides of the substrate layer, characterized in that: The conductive layer includes, from the inside to the outside, a metal copper sputtering layer, a metal copper electroplating layer, and a protective layer; wherein the metal copper sputtering layer is a layer of metal copper with a thickness of 5-15 nm formed on both sides of the substrate layer by a vacuum sputtering process, the metal copper electroplating layer is a layer of metal copper with a thickness of 100-500 nm grown on the outer surface of the metal copper sputtering layer by a water electroplating process, and the protective layer is a dense protective layer formed after passivation treatment of the outer surface of the metal copper electroplating layer; the protective layer is a 5-15 nm metal chromium protective layer formed by an electroplating process; the substrate layer is made of a polyester film to which a polyester functional masterbatch is added, and the polyester functional masterbatch is prepared from the following raw materials in parts by weight: 30-50 parts by weight of polyisophthalamide, 1-3 parts by weight of cobalt neodecanoate, 3-5 parts by weight of butylated hydroxytoluene, 5-10 parts by weight of 1,4-diiodobenzene, 20-30 parts by weight of silicon dioxide, and 50-100 parts by weight of PET.

2. The composite copper foil film according to claim 1, wherein The thickness of the metal copper sputtering layer is 5-8 nm, the thickness of the metal copper electroplating layer is 300-400 nm, and the thickness of the metal chromium protective layer is 5-8 nm.

3. The composite copper foil film according to claim 1, wherein A barrier layer of 2-3 nm silicon dioxide is formed by sputtering on the outer side of the substrate layer between the conductive layer and the substrate layer.

4. The composite copper foil film according to claim 3, wherein A corona layer with a thickness of 1-2 nm is formed on the surface of the substrate layer, and the barrier layer is formed on the outer side of the corona layer.

5. The composite copper foil film according to claim 1, wherein The polyester film constituting the substrate layer is a single-layer polyester film containing 5-20 wt% of polyester functional masterbatch, or a three-layer polyester film comprising A layer, B layer and C layer containing 5-20 wt% of polyester functional masterbatch.

6. A method for preparing a composite copper foil film according to claim 1, wherein the composite copper foil film comprises a substrate layer and conductive layers attached to both sides of the substrate layer, the method comprising the following steps: forming the substrate layer from a polyester film to which a polyester functional masterbatch is added; corona treating both sides of the substrate layer to form a corona layer; forming a barrier layer on the outer side of the corona layer; and forming the conductive layer on the outer side of the barrier layer; the polyester functional masterbatch being prepared from the following raw materials in parts by weight: 30-50 parts by weight of poly(m-xylylene diamide), 1-3 parts by weight of cobalt neodecanoate, 3-5 parts by weight of butylated hydroxytoluene, 5-10 parts by weight of 1,4-diiodobenzene, 20-30 parts by weight of silica, and 50-100 parts by weight of PET.

7. The preparation method according to claim 6, wherein The polyester film constituting the substrate layer is a single-layer polyester film containing 5 to 20 wt% of a polyester functional masterbatch, and the polyester film is prepared by the following steps: The following components in weight ratio: 80-95 wt% of PET resin and 5-20 wt% of polyester functional masterbatch are measured by electronic scales and put into a mixing bin for mixing to form a mixture; The mixed material then enters the vented twin-screw extruder, and the temperature of the twin-screw extruder is adjusted to 270℃~280℃; After the material is melted in the extruder, it is filtered and extruded into thick sheets. The thickness and profile of the thick sheets can be adjusted by the extruder extrusion volume, the casting roller speed, and the die opening. The thick sheet is preheated at a temperature of 50°C to 90°C, placed in an infrared heating zone at 300°C to 500°C, and longitudinally stretched at a line speed of 40 to 150 m / min with a longitudinal stretching ratio of 4.0 to obtain a stretched sheet; The stretched sheet is preheated at a temperature of 90°C to 120°C, and transversely stretched at a temperature of 100°C to 160°C with a transverse stretching ratio of 3.8; then, it is shaped at a temperature of 160°C to 240°C, and then cooled at a temperature of 100°C to 50°C to obtain a polyester film for composite copper foil film.

8. The preparation method according to claim 6, wherein The polyester film constituting the substrate layer is a three-layer polyester film comprising layers A and C containing 5 to 20 wt% of a polyester functional masterbatch. The polyester film is prepared by the following steps: The following components in weight ratio: 80-95 wt% of PET resin and 5-20 wt% of polyester functional masterbatch are measured by electronic scales and put into a mixing bin for mixing to form a mixture; The mixed material then enters the vented twin-screw extruder E; 100% PET resin was put into the pre-crystallizer and pre-crystallized at 160°C for 15 minutes. The PET material then entered the drying tower and was dried at 160°C for 6 hours before entering the single-screw extruder F. Adjust the temperature of twin-screw extruders E and F to 270℃~280℃; After the materials are melted in the two extruders and filtered, the material extruded from the twin-screw extruder E is used as the surface A and C layers, and the material extruded from the single-screw extruder F is used as the middle B layer. Through a multi-layer co-extrusion process, a three-layer composite thick sheet is produced. The thickness and profile of the thick sheet can be adjusted by the extruder extrusion volume, the casting roller speed, and the die opening. The thick sheet is preheated at a temperature of 50°C to 90°C, placed in an infrared heating zone at 300°C to 500°C, and longitudinally stretched at a line speed of 40 to 150 m / min with a longitudinal stretching ratio of 4.0 to obtain a stretched sheet; The stretched sheet is preheated at 90°C to 120°C, and transversely stretched at 100°C to 160°C with a transverse stretching ratio of 3.8; then, it is shaped at 160°C to 240°C, and then cooled at 100°C to 50°C to obtain the three-layer polyester film.

9. The preparation method according to claim 7 or 8, further comprising the step of preparing the polyester functional masterbatch: adding 50-100 parts by weight of powdered PET, 20-30 parts by weight of nano-silica, 30-50 parts by weight of powdered polyisophthalamide, 1-3 parts by weight of powdered cobalt neodecanoate, 3-5 parts by weight of powdered butylated hydroxytoluene, and 5-10 parts by weight of powdered 1,4-diiodobenzene to a high-speed mixer at room temperature, pre-dispersing and mixing the mixture at a speed of 1500-2000 rpm for 30-60 minutes to form a mixture; then melt-extruding the mixture through a twin-screw extruder, followed by water cooling and pelletizing or slicing to obtain the polyester functional masterbatch.

10. The preparation method according to claim 6, wherein The conductive layer includes, from the inside to the outside, a metal copper sputtering layer, a metal copper electroplating layer and a protective layer; wherein, the steps of forming the conductive layer include: forming a metal copper sputtering layer on the outside of the barrier layer by a vacuum sputtering process; growing a metal copper electroplating layer on the outer surface of the metal copper sputtering layer by a water electroplating process; and forming a protective layer on the outer surface of the metal copper electroplating layer by an electroplating process.

Images