Method for preparing PET (Polyethylene Terephthalate) copper foil by ionic liquid additive photo-reduction method

Abstract

The invention relates to the technical field of PET copper foil preparation, in particular to a method for preparing a PET copper foil through an ionic liquid additive photo-reduction method. The method comprises the following steps: performing surface cleaning treatment on a PET film to obtain a pretreated PET film; the pretreated PET film is subjected to micro roughening treatment, and the PET film subjected to micro roughening treatment is obtained; the PET film subjected to micro roughening treatment is placed in a photoreduction solution, the PET copper foil is obtained after illumination, washing and drying, and the photoreduction solution is composed of copper sulfate pentahydrate, an ionic liquid additive, ethyl alcohol and a photoinitiator. According to the preparation method, the PET copper foil can be prepared in an environment-friendly and stable manner by using the ionic liquid additive to carry out the photo-reduction method, and the prepared PET copper foil has relatively high tensile strength and ductility and also has relatively low surface roughness.

Description

Technical Field

[0001] The invention relates to the technical field of PET copper foil preparation, in particular to a method for preparing PET copper foil by an ionic liquid auxiliary agent photoreduction method. Background Art

[0002] The rapid development of the lithium battery industry is inseparable from copper foil. As an important component of lithium batteries, copper foil plays a key role in the performance and stability of batteries. With the rapid development of fields such as electric vehicles and digital products, the demand for high-performance, high-quality lithium batteries continues to increase, which in turn drives the rapid growth of the copper foil market. Copper foil has excellent electrical conductivity, good thermal conductivity and excellent chemical stability, making it an indispensable material in the manufacture of lithium batteries. With the continuous advancement of technology, the production process of copper foil is also being continuously optimized to meet the market demand for high-performance batteries.

[0003] Traditional pure metal copper foil is easy to puncture the battery separator after a tram accident, causing a short circuit between the positive and negative electrodes and causing a fire, and its safety performance has attracted people's attention. Compared with traditional copper foil, composite copper foil is lighter and softer, which can effectively reduce the weight and volume of the battery and increase the energy density of the battery. In addition, the special composite structure of copper foil can effectively prevent the short circuit caused by copper foil breakage in the event of an accident. Therefore, composite copper foil has become one of the most promising materials in the field of lithium-ion batteries.

[0004] Magnetron sputtering and vacuum evaporation are commonly used preparation processes for composite copper foil, but these two methods have problems such as high equipment cost and high technical difficulty, which greatly reduce the quality of composite copper foil and increase the production cost of batteries. Therefore, seeking a suitable preparation process can help composite copper foil gain a larger application market. Compared with traditional composite copper foil preparation methods, the photoreduction method has the advantages of low equipment cost, stable process flow, and environmental friendliness. Therefore, the development of a new photoreduction method for preparing composite copper foil has far-reaching significance for the low-cost application of composite copper foil and promoting the sustainable and healthy development of the lithium battery industry.

[0005] At present, most domestic companies that produce composite copper foil mainly use magnetron sputtering and vacuum evaporation methods, and only a few companies use water electroplating. The equipment and process of magnetron sputtering and vacuum evaporation are complex, requiring high cost investment, resulting in high production costs; at the same time, these methods have a slow production speed and are difficult to meet the needs of large-scale production, thus affecting production capacity and production efficiency. In addition, magnetron sputtering and vacuum evaporation will produce waste gas and waste liquid during the production process, causing environmental pollution. The uniformity of the coating of water electroplating is affected by factors such as electric field distribution and current density during the electroplating process, resulting in the problem of uneven surface coating thickness of the composite copper foil. Therefore, the development of a process method with low equipment cost and stable preparation conditions is of great significance for the large-scale application of composite copper foil. Summary of the invention

[0006] Aiming at the problems that enterprises currently encounter in the actual production of composite copper foil: 1. Complex equipment and process, high cost investment; 2. Low production capacity and efficiency; 3. Environmental pollution problems still exist; 4. Insufficient quality stability of composite copper foil. The present invention proposes a method for preparing PET copper foil by ionic liquid additive photoreduction method, and provides an ionic liquid additive that can improve the photoreduction rate and is environmentally friendly, with the purpose of optimizing the production process of PET copper foil and solving the problems of high equipment cost, large investment, and complex production process in the production process of PET copper foil.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] A method for preparing a photoreduction solution comprises the following steps:

[0009] Step (1): uniformly mixing copper sulfate pentahydrate, an ionic liquid additive and ethanol to obtain a basic solution;

[0010] Step (2): under light-proof conditions, add the photoinitiator into the base solution and stir evenly to obtain a photoreduction solution.

[0011] Furthermore, the ionic liquid additive has the following characteristics:

[0012] The ionic liquid auxiliary agent is an imidazole type ionic liquid; the functional group of the ionic liquid is a -NH2 group; and the anion of the ionic liquid is any anion.

[0013] Furthermore, the ionic liquid auxiliary agent is at least one of 1-aminopropyl-3-methylimidazolium chloride, 1-aminopropyl-3-methylimidazolium bromide, 1-aminopropyl-3-methylimidazolium tetrafluoroborate, and 1-aminoethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

[0014] Furthermore, in step (1), the Cu2+ The content of ions is 0.10M~0.16M; Cu 2+ The molar ratio of ions to ionic liquid additives is 1:4.

[0015] Furthermore, the photoinitiator is one of I-1173 photoinitiator and I-2959 photoinitiator.

[0016] Furthermore, in step (2), the Cu 2+ The molar ratio of ions to photoinitiators was 1:2.

[0017] A method for preparing PET copper foil by an ionic liquid additive photoreduction method comprises the following steps:

[0018] Step S1: performing surface cleaning treatment on the PET film to obtain a pre-treated PET film;

[0019] Step S2: performing micro-roughening treatment on the pre-treated PET film to obtain a micro-roughened PET film;

[0020] Step S3: placing the roughened PET film in the photoreduction solution of claim 7, irradiating it with light, washing it, and drying it to obtain a PET copper foil.

[0021] Furthermore, in step S1, the specific preparation process of the pre-treated PET film includes the following steps:

[0022] The PET film was placed in acetone, ethanol and deionized water for ultrasonic cleaning for 10-20 minutes respectively, then washed with deionized water, and dried at 20-40° C. to obtain a pretreated PET film.

[0023] Furthermore, in the step S2, the micro-roughening treatment is a plasma micro-roughening treatment performed in an air atmosphere.

[0024] Furthermore, in step S3, the wavelength of the light source for illumination is 365nm-410nm, and the temperature of the solution after illumination is 10-40°C.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The method for preparing PET copper foil by photoreduction method with ionic liquid additives of the present invention uses a functionalized ionic liquid synthesized in a directional manner as an additive for the photoreduction method, so that it can produce a synergistic effect with a photoinitiator and copper sulfate in a solution, so that the PET copper foil can be prepared under light conditions; the photoinitiator will be decomposed into two free radicals under light irradiation, among which the carbonyl free radical with strong reducing ability can continuously convert Cu 2+ Ion reduction to Cu 0The present invention uses a new ionic liquid additive and a photoinitiator to prepare a PET composite copper foil under light conditions, which simplifies the process of preparing the traditional PET copper foil by cumbersome means such as magnetron sputtering and vacuum evaporation, reduces production costs and environmental pollution, and is expected to replace the traditional PET copper foil preparation method to realize green and safe preparation technology.

[0027] 2. The present invention discloses a method for preparing PET copper foil by using an ionic liquid additive photoreduction method. The photoreduction method using an ionic liquid additive can prepare PET copper foil in an environmentally friendly and stable manner, has high process stability, low equipment cost, and can realize continuous production of composite copper foil. The prepared PET copper foil has high tensile strength and elongation, and low surface roughness. The tensile strength and elongation at room temperature can be as high as 335.8 MPa and 29.1%, respectively, and the surface roughness can be as low as 2.986 μm.

[0028] 3. The method for preparing PET copper foil by photoreduction method using an ionic liquid additive of the present invention provides an environmentally friendly ionic liquid additive that can improve the photoreduction rate. The method for preparing PET composite copper foil by photoreduction method using an ionic liquid additive has the advantages of low cost, easy continuous and industrial production, and environmental friendliness, which is conducive to large-scale application and production in the preparation of composite copper foil. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0030] Figure 1 It is the reaction mechanism diagram of Examples 1-5 in the present invention;

[0031] Figure 2 is a cross-sectional microscopic morphology of the PET composite copper foil prepared in Example 1 of the present invention;

[0032] Figure 3 This is a superimposed distribution diagram of Cu and C elements in a cross section of the PET composite copper foil prepared in Example 1 of the present invention;

[0033] Figure 4 is a cross-sectional C element distribution diagram of the PET composite copper foil prepared in Example 1 of the present invention;

[0034] Figure 5 This is a cross-sectional Cu element distribution diagram of the PET composite copper foil prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The PET film in this embodiment has a thickness of 4.5 μm and can be purchased from Dongguan Yisite Packaging Products Co., Ltd.

[0037] Example 1: A method for preparing PET copper foil by ionic liquid additive photoreduction method, comprising the following steps:

[0038] Step S1: placing the PET film in acetone, ethanol, and deionized water for ultrasonic cleaning for 10 minutes respectively, then washing with deionized water, and drying at 20° C. to obtain a pretreated PET film;

[0039] Step S2: performing plasma micro-roughening treatment on the pre-treated PET film in an air atmosphere to obtain a micro-roughened PET film;

[0040] Step S3: placing the micro-roughened PET film in a photoreduction solution, irradiating it with light (light source wavelength 365 nm, solution temperature after irradiation is 25° C.), washing it, and drying it to obtain a PET copper foil;

[0041] The preparation method of the photoreduction solution is as follows:

[0042] Step (1): using 1-aminopropyl-3-methylimidazolium chloride as an ionic liquid auxiliary agent, and uniformly mixing copper sulfate pentahydrate, 1-aminopropyl-3-methylimidazolium chloride and ethanol to obtain a basic solution;

[0043] Step (2): using I-1173 photoinitiator as an initiator, adding I-1173 photoinitiator to the base solution under light-proof conditions, stirring evenly, and obtaining a photoreduction solution;

[0044] Among them, the concentration of 1-aminopropyl-3-methylimidazolium chloride is 0.4M, Cu 2+ The ion concentration was 0.1M and the concentration of I-1173 photoinitiator was 0.2M.

[0045] Example 2: A method for preparing PET copper foil by ionic liquid additive photoreduction method, comprising the following steps:

[0046] Step S1: placing the PET film in acetone, ethanol, and deionized water for ultrasonic cleaning for 12 minutes respectively, then washing with deionized water, and drying at 25° C. to obtain a pretreated PET film;

[0047] Step S2: performing plasma micro-roughening treatment on the pre-treated PET film in an air atmosphere to obtain a micro-roughened PET film;

[0048] Step S3: placing the micro-roughened PET film in a photoreduction solution, irradiating it with light (light source wavelength 380nm, solution temperature after irradiation is 25°C), washing it, and drying it to obtain a PET copper foil;

[0049] The preparation method of the photoreduction solution is as follows:

[0050] Step (1): using 1-aminopropyl-3-methylimidazolium bromide as an ionic liquid auxiliary agent, and uniformly mixing copper sulfate pentahydrate, 1-aminopropyl-3-methylimidazolium bromide and ethanol to obtain a basic solution;

[0051] Step (2): using I-1173 photoinitiator as an initiator, adding I-1173 photoinitiator to the base solution under light-proof conditions, stirring evenly, and obtaining a photoreduction solution;

[0052] Among them, the concentration of 1-aminopropyl-3-methylimidazolium bromide is 0.48M, Cu 2+ The ion concentration was 0.12M and the concentration of I-1173 photoinitiator was 0.24M.

[0053] Example 3: A method for preparing PET copper foil by ionic liquid additive photoreduction method, comprising the following steps:

[0054] Step S1: placing the PET film in acetone, ethanol, and deionized water for ultrasonic cleaning for 15 minutes respectively, then washing with deionized water, and drying at 30° C. to obtain a pretreated PET film;

[0055] Step S2: performing plasma micro-roughening treatment on the pre-treated PET film in an air atmosphere to obtain a micro-roughened PET film;

[0056] Step S3: placing the micro-roughened PET film in a photoreduction solution, irradiating it with light (light source wavelength 365 nm, solution temperature after irradiation is 25° C.), washing it, and drying it to obtain a PET copper foil;

[0057] The preparation method of the photoreduction solution is as follows:

[0058] Step (1): using 1-aminopropyl-3-methylimidazolium tetrafluoroborate as an ionic liquid auxiliary agent, copper sulfate pentahydrate, 1-aminopropyl-3-methylimidazolium tetrafluoroborate and ethanol are uniformly mixed to obtain a basic solution;

[0059] Step (2): using I-1173 photoinitiator as an initiator, adding I-1173 photoinitiator to the base solution under light-proof conditions, stirring evenly, and obtaining a photoreduction solution;

[0060] The concentration of 1-aminopropyl-3-methylimidazolium tetrafluoroborate is 0.64 M, Cu 2+ The ion concentration was 0.16M and the concentration of I-1173 photoinitiator was 0.32M.

[0061] Example 4: A method for preparing PET copper foil by ionic liquid additive photoreduction method, comprising the following steps:

[0062] Step S1: placing the PET film in acetone, ethanol, and deionized water for ultrasonic cleaning for 15 minutes respectively, then cleaning with deionized water, and drying at 35° C. to obtain a pretreated PET film;

[0063] Step S2: performing plasma micro-roughening treatment on the pre-treated PET film in an air atmosphere to obtain a micro-roughened PET film;

[0064] Step S3: placing the micro-roughened PET film in a photoreduction solution, irradiating it with light (light source wavelength 410 nm, solution temperature after irradiation is 25° C.), washing it, and drying it to obtain a PET copper foil;

[0065] The preparation method of the photoreduction solution is as follows:

[0066] Step (1): using 1-aminoethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt as an ionic liquid auxiliary agent, and uniformly mixing copper sulfate pentahydrate, 1-aminoethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and ethanol to obtain a basic solution;

[0067] Step (2): using I-1173 photoinitiator as an initiator, adding I-1173 photoinitiator to the base solution under light-proof conditions, stirring evenly, and obtaining a photoreduction solution;

[0068] The concentration of 1-aminoethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt is 0.4 M, Cu 2+ The ion concentration was 0.1M and the concentration of I-1173 photoinitiator was 0.2M.

[0069] Example 5: A method for preparing PET copper foil by ionic liquid additive photoreduction method, comprising the following steps:

[0070] Step S1: placing the PET film in acetone, ethanol, and deionized water for ultrasonic cleaning for 20 minutes respectively, then cleaning with deionized water, and drying at 40° C. to obtain a pretreated PET film;

[0071] Step S2: performing plasma micro-roughening treatment on the pre-treated PET film in an air atmosphere to obtain a micro-roughened PET film;

[0072] Step S3: placing the micro-roughened PET film in a photoreduction solution, irradiating it with light (light source wavelength 365 nm, solution temperature after irradiation is 25° C.), washing it, and drying it to obtain a PET copper foil;

[0073] The preparation method of the photoreduction solution is as follows:

[0074] Step (1): using 1-aminopropyl-3-methylimidazolium chloride as an ionic liquid auxiliary agent, and uniformly mixing copper sulfate pentahydrate, 1-aminopropyl-3-methylimidazolium chloride and ethanol to obtain a basic solution;

[0075] Step (2): using I-2959 photoinitiator as an initiator, adding I-2959 photoinitiator to the base solution under light-proof conditions, stirring evenly, and obtaining a photoreduction solution;

[0076] Among them, the concentration of 1-aminopropyl-3-methylimidazolium chloride is 0.4M, Cu 2+ The ion concentration was 0.1M and the concentration of I-2959 photoinitiator was 0.2M.

[0077] Comparative Example 1: A method for preparing PET copper foil by an ionic liquid additive photoreduction method, comprising the following steps:

[0078] Compared with Example 5, the wavelength of the light source in Comparative Example 1 is 420 nm, and the other steps are the same as those in Example 5.

[0079] Comparative Example 2: A method for preparing PET copper foil by an ionic liquid additive photoreduction method, comprising the following steps:

[0080] Compared with Example 5, the concentration of 1-aminopropyl-3-methylimidazolium chloride in Comparative Example 2 is 0.1 M, and the other steps are the same as those in Example 5.

[0081] Comparative Example 3: A method for preparing PET copper foil by an ionic liquid additive photoreduction method, comprising the following steps:

[0082] Compared with Example 5, the concentration of I-2959 photoinitiator in Comparative Example 3 is 0.1 M, and the other steps are the same as those in Example 5.

[0083] Comparative Example 4: A method for preparing PET copper foil by an ionic liquid additive photoreduction method, comprising the following steps:

[0084] Compared with Example 5, the Cu 2+ The ion concentration is 0.5 M, and the other steps are the same as in Example 5.

[0085] Experiment: Take the PET copper foil obtained in Examples 1-5 and Comparative Examples 1-4 to prepare samples, test their tensile strength, elongation at break and roughness respectively and record the test results:

[0086] Tensile strength and elongation at break: the test refers to the national standard GB / T 1040.3-2006. The test results of the present invention are all test data in the MD direction.

[0087] Roughness test: Use a roughness tester to scan or contact the copper foil surface using a mechanical probe, and then calculate the surface roughness parameters using a built-in algorithm.

[0088] Test results:

[0089]

[0090]

[0091] According to the data in the above table, we can clearly draw the following conclusions:

[0092] 1. Compared with Comparative Example 1, the tensile properties of the product obtained in Example 5 are better. It can be seen that compared with the light source with a wavelength of 420nm, the light source with a wavelength of 365nm can more effectively promote the synergistic effect between the photoreduction aid, the photoinitiator, and the copper ions, and prepare a denser copper foil. The reason may be that the wavelength of 365nm is shorter and the excitation energy is higher, which can excite a large number of copper ions to nucleate in a shorter time, increase the nucleation density of copper ions, and thus improve the mechanical properties of the PET copper foil.

[0093] 2. Compared with Examples 1-5, the tensile properties of the products obtained in Comparative Examples 2, 3 and 4 decreased and the roughness increased, indicating that the performance of the photoreduction solution prepared by the present invention is affected by the composition ratio thereof. By selecting the composition ratio within the range, a PET copper foil with better mechanical properties and lower surface roughness can be prepared.

[0094] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process method article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process method article or device.

[0095] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. 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 photoreduction solution, characterized in that: The following steps are involved: Step (1): uniformly mixing copper sulfate pentahydrate, an ionic liquid additive and ethanol to obtain a basic solution; Step (2): under light-proof conditions, add the photoinitiator into the base solution and stir evenly to obtain a photoreduction solution.

2. The method for preparing a photoreduction solution according to claim 1, characterized in that: The ionic liquid additive has the following characteristics: The ionic liquid auxiliary agent is an imidazole type ionic liquid; the functional group of the ionic liquid is a -NH2 group; and the anion of the ionic liquid is any anion.

3. The method for preparing a photoreduction solution according to claim 2, characterized in that: The ionic liquid auxiliary agent is at least one of 1-aminopropyl-3-methylimidazolium chloride, 1-aminopropyl-3-methylimidazolium bromide, 1-aminopropyl-3-methylimidazolium tetrafluoroborate, and 1-aminoethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

4. The method for preparing a photoreduction solution according to claim 1, characterized in that: In the step (1), the Cu 2+ The content of ions is 0.10M~0.16M; Cu 2+ The molar ratio of ions to ionic liquid additives is 1:

4.

5. The method for preparing a photoreduction solution according to claim 1, characterized in that: The photoinitiator is one of I-1173 photoinitiator and I-2959 photoinitiator.

6. The method for preparing a photoreduction solution according to claim 1, characterized in that: In the step (2), the Cu in the photoreduction solution 2+ The molar ratio of ions to photoinitiators was 1:

2.

7. A photoreduction solution prepared according to the preparation method according to any one of claims 1 to 6.

8. A method for preparing PET copper foil by ionic liquid additive photoreduction method, characterized in that: The following steps are involved: Step S1: performing surface cleaning treatment on the PET film to obtain a pre-treated PET film; Step S2: performing micro-roughening treatment on the pre-treated PET film to obtain a micro-roughened PET film; Step S3: placing the roughened PET film in the photoreduction solution of claim 7, irradiating it with light, washing it, and drying it to obtain a PET copper foil.

9. PET copper foil prepared by the method for preparing PET copper foil by ionic liquid auxiliary photoreduction method according to claim 8.

10. The use of the PET copper foil according to claim 9, characterized in that: It is used in the preparation of conductive composite materials and lithium-ion batteries.

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