Composite coating and method for its production and use

Abstract

The application discloses a composite coating and a preparation method and application thereof, and relates to the technical field of composite coatings.The application provides a composite coating, which comprises a porous base film layer, an aramid nanofiber layer and a rigid coating layer arranged in sequence.The application provides the composite coating, the aramid nanofiber layer is used as a mechanical transition layer of the rigid coating layer and the flexible porous base film layer, interface regulation is carried out to realize a stable interface structure of the flexible porous base film layer and the rigid coating layer, and problems, such as separation of the rigid coating layer and the flexible porous base film layer, are effectively solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite coating, and particularly to a composite coating, a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of electronic technology, the significant advantages of lightweight, bendability and durability have gradually become an important development direction of the electronic industry. In the fields of wearable technology, electronic displays and intelligent sensors, such devices have shown great application potential and broad development prospects. However, the current flexible electronic devices mainly rely on expensive and complex material systems such as polyimide and conductive polymers, which seriously restricts their large-scale commercialization process. Polyolefin materials are ideal materials for flexible electronic device substrates due to their excellent mechanical properties, good chemical stability and significant cost-effectiveness. However, traditional polyolefin materials still face many technical challenges in flexible electronic applications, mainly including poor thermal stability and insufficient interfacial adhesion with other functional coatings, which seriously hinder their widespread application in the field of flexible electronics.

[0003] Poly(p-phenylene terephthalamide) (PPTA), also known as para-aramid fiber (Kevlar), was first developed and produced by Dupont in the 1960s-1970s. PPTA is a rigid liquid crystal polymer with excellent thermal stability and mechanical properties. As reported in Chinese patents such as CN104993089A and CN107452921A, PPTA has been widely used to improve the heat resistance of polyolefin-based separators for lithium batteries. However, there is no report on using PPTA as a transition layer to form a firm interface structure between rigid coatings and flexible base films. In addition, the para-aramid coating technology proposed in Chinese patent application No. 201510453815.X and Japanese patent No. 2010-254731 requires additional adhesives to achieve the effect of bonding the aramid and polyolefin composite film interface. In Chinese patent CN 111883777A, plasma cleaning is required to ensure that the metal plating layer has sufficient adhesion to the substrate.

[0004] Therefore, how to improve the performance of polyolefin materials to better meet the needs of flexible electronic devices has become a key problem to be solved in the current technical field. In view of this, the present application is proposed. SUMMARY

[0005] Based on this, the purpose of the present application is to overcome the shortcomings of the prior art and provide a composite coating, a preparation method and application thereof.

[0006] To achieve the above object, the technical scheme adopted by the present application is as follows: The present application provides a composite coating, which comprises a porous base film layer, an aramid nanofiber layer and a rigid coating layer arranged in sequence; the porous base film layer is a porous base film layer with a porous structure formed by polyolefin fibers; the aramid nanofiber layer is an aramid nanofiber layer with a porous structure formed by aramid nanofibers; and the rigid coating layer is composed of at least one of copper, aluminum, platinum, gold, silver, titanium, molybdenum, silicon, aluminum oxide, indium tin oxide, silicon oxide and titanium oxide.

[0007] Preferably, the thickness of the porous base film layer is 0.1-10 μm, the pore size of the porous base film layer is 20-80 nm, and the porosity is 30-60%; and the diameter of the polyolefin fibers is 30-60 nm.

[0008] Preferably, the thickness of the aramid nanofiber layer is ≥0.05 μm, the pore size of the aramid nanofiber layer is 20-80 nm, and the porosity is 10-50%; and the diameter of the aramid nanofibers is 10-50 nm.

[0009] Preferably, the thickness of the rigid coating layer is 0.01-1 μm.

[0010] Preferably, the pore size of the porous base film layer is 30-40 nm, and the porosity is 35-50%; and the diameter of the polyolefin fibers is 45-55 nm.

[0011] Preferably, the pore size of the aramid nanofiber layer is 30-50 nm, and the porosity is 30-40%; and the diameter of the aramid nanofibers is 20-30 nm.

[0012] The present application utilizes the deprotonation + re-protonation process of aramid fibers to enable the entanglement and nanometer confinement effect of the aramid nanofiber layer and the flexible porous base film layer, thereby solving the problem that the existing aramid nanofiber and porous base film need to be added with an adhesive or surface treated to realize the interface combination. The present application provides a composite coating, which uses the aramid nanofiber layer as a mechanical transition layer of the rigid coating layer and the flexible porous base film layer, performs interface regulation to realize the stable interface structure of the flexible base film layer and the rigid coating layer, and effectively solves the problem of separation of the rigid coating layer and the flexible base film layer.

[0013] Preferably, the thickness of the porous base film layer is 2-5 μm; the thickness of the aramid nanofiber layer is 0.2-1 μm; and / or the thickness of the rigid coating layer is 0.05-0.5 μm.

[0014] Further preferably, the thickness of the porous base film layer is 2.5-4 μm.

[0015] Preferably, the porous base film layer is formed by a porous structure film layer of polyolefin fibers; the polyolefin is at least one of polypropylene and polyethylene; further preferably, the polyolefin is polyethylene.

[0016] Preferably, the porous structure film layer of polyolefin fibers can be a commercially available product or self-made. Specifically, it can be prepared by a wet or dry drawing method.

[0017] Preferably, the porous structure film layer of polyolefin fibers is prepared by the following method: polyolefin-based polymer and lubricant are added to a twin-screw extruder, blended and extruded into a gel sheet, then stretched into a polyolefin fiber ultra-thin film by a biaxial stretching process, and finally treated by extraction and annealing to prepare a polyolefin-based film material, i.e. the porous structure film layer of polyolefin fibers. The stretching ratio is (5-20) times (5-20).

[0018] Preferably, the prepared porous structure film layer of polyolefin fibers has a thickness of (0.1-5) ± 0.5 μm.

[0019] Preferably, the application further provides a preparation method of the composite coating, comprising the following steps:

[0020] S1, uniformly mixing aramid fibers, an alkaline solution and an organic solvent to obtain an aramid nanofiber dispersion;

[0021] S2, coating the aramid nanofiber dispersion on the surface of the porous base film layer, immersing in a mixed solution after annealing, and placing in a magnetron sputtering device after washing and drying to obtain the composite coating.

[0022] The inventors found in actual experiments that the porous base film layer and the aramid nanofiber layer, and the aramid nanofiber layer and the rigid coating layer in the composite coating are mutually entangled. During annealing, the solvent volatilization of aramid nanofiber (ANF) and the partial melting of polyolefin chains of the porous base film work together to promote the rapid diffusion of polyolefin molecular chains to the surface of adjacent ANF and mutual entanglement, thereby forming a firm interfacial interlocking between ANF and the polyolefin-based substrate. In addition, the particles after magnetron sputtering are bonded with the high specific surface area ANF through nano-limiting effect (physical adsorption) and the formation of coordination structures with nitrogen (N) and oxygen (O) elements on the ANF, further improving the stability of the coating. At the same time, the aramid nanofiber layer (elastic modulus 40-60 GPa) is used as a mechanical transition layer between the rigid coating layer (elastic modulus > 50 GPa) and the flexible base film layer (elastic modulus < 30 GPa), forming a gradient modulus interface to reduce the interface stress concentration, effectively solving the problem of separation of the rigid coating layer and the flexible base film layer under dynamic mechanical action, and significantly improving the interface stability of the material.

[0023] The inventors found that the pore size distribution and porosity of the porous base film layer of the final prepared composite coating are synergistically regulated by the annealing temperature and the magnetron sputtering power during the actual research process. Studies have shown that within a suitable temperature range, the thermal activation effect can promote the migration and rearrangement of polyolefin chains, significantly enhancing the interfacial bonding strength by forming a topological entanglement structure with aramid nanofibers. In addition, increasing the magnetron sputtering power can improve the bonding of rigid nanoparticles and aramid nanofibers. However, when the process parameters exceed the critical threshold, the melting of the substrate caused by overheating will destroy the integrity of the porous structure.

[0024] Preferably, in the step S1, at least one of the following (1)-(4) is satisfied:

[0025] (1) the aramid fiber is a para-aramid fiber or a meta-aramid fiber;

[0026] (2) the mass-volume ratio of the aramid fiber, the alkaline solution, and the organic solvent is (0.1-2) g:(3-20) mL:100 mL;

[0027] (3) the alkaline solution is a mixture of a base and a proton donor, and the mass-volume ratio of the base and the proton donor is (0.1-10) g:(2-20) mL;

[0028] (4) the organic solvent is at least one of dimethyl sulfoxide and dimethyl fumarate.

[0029] Preferably, the base is at least one of sodium hydroxide and potassium hydroxide; and the proton donor is at least one of water, ethanol, isopropanol, ethylene glycol, propylene glycol, and butanediol.

[0030] Preferably, the meta-aramid fiber is, for example, (Kevlar®, DuPont), (Conex®, Teijin), (Twaron®, China Taishan New Material), and the para-aramid fiber is, for example, (Kevlar®, DuPont), (Conex®, Teijin), (Twaron®, China Taishan New Material).

[0031] Preferably, the aramid fiber is a Kevlar fiber purchased from DuPont.

[0032] Further preferably, the base is potassium hydroxide.

[0033] Preferably, in the step S2, at least one of the following (5)-(9) is satisfied:

[0034] (5) the annealing temperature is 100-130°C, and the annealing time is 10-20 min;

[0035] (6) the mixed solution is a mixture of dimethyl sulfoxide and isopropanol, the volume ratio of dimethyl sulfoxide to isopropanol is (0.1-0.5):1;

[0036] (7) the soaking time is 5-30 min;

[0037] (8) the vacuum degree of the magnetron sputtering is 10 -4 Pa, the film coating power of the magnetron sputtering is 5-200 W, and the time of the magnetron sputtering is 20-1500 s;

[0038] (9) the target material of the magnetron sputtering is at least one of copper, aluminum, platinum, gold, silver, titanium, molybdenum, silicon, aluminum oxide, indium tin oxide, silicon oxide, and titanium oxide.

[0039] Further preferably, the annealing temperature is 120-130℃.

[0040] Further preferably, the soaking time is 10-20 min.

[0041] Further preferably, the film coating power of the magnetron sputtering is 25-100 W, and the time of the magnetron sputtering is 50-300 s.

[0042] In addition, the application provides the use of the composite coating in the preparation of a flexible electronic device; specifically, the application discloses the use of the composite coating in the preparation of a wearable sensor, an electronic skin, and a flexible display screen.

[0043] Compared with the prior art, the application has the following beneficial effects: the operation steps of the application are simple, and the process equipment has the possibility of realizing large-scale and continuous production. The application utilizes the deprotonation + re-protonation process of aramid fibers to enable the entanglement and nano-limitation effect of the aramid nanofiber layer and the flexible porous base film layer, thereby solving the problem that the existing aramid fibers and porous base films need to be added with an adhesive or surface treated to realize interface bonding. The application provides a composite coating, which uses the aramid nanofiber layer as a rigid coating and a mechanical transition layer of the flexible porous base film layer, performs interface regulation to realize a stable interface structure of the flexible porous base film layer and the rigid coating, and effectively solves the problem of separation of the rigid coating and the flexible base film layer. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 A scanning electron microscope image of the composite coating prepared in Example 1. DETAILED DESCRIPTION

[0045] For better illustrating the purpose, technical scheme and advantages of the present application, the present application will be further described below in conjunction with the drawings and specific examples. The purpose is to understand the content of the present application in detail, rather than to limit the present application. All other examples obtained by the ordinary skilled in the art without making creative efforts fall within the protection scope of the present application. The experimental reagents and instruments designed for the implementation and comparative examples of the present application are all common reagents and instruments unless specifically stated, and can be obtained from commercial channels. In the implementation and comparative examples, the experimental methods used are all conventional methods unless specifically stated, and the raw materials used in parallel experiments are the same batch of raw materials unless specifically stated.

[0046] Examples and comparative examples

[0047] Examples 1-16

[0048] Example 1

[0049] A composite coating, comprising a porous base film layer, an aramid nanofiber layer and a rigid coating layer arranged in sequence; the porous base film layer is a porous structure film layer formed by polyolefin fibers, i.e. a polyethylene porous film, with a pore size of 40 nm, a porosity of 55±5%, and a thickness of 2.5±0.5 μm (purchased from Guangzhou Guna Technology Co., Ltd.);

[0050] A preparation method of the composite coating, comprising the following steps:

[0051] (1) uniformly mixing Kevlar fibers, an alkaline solution and an organic solvent to obtain an aramid nanofiber dispersion;

[0052] Preparation of the alkaline solution: the alkaline solution is a mixture of KOH and a proton donor, and the KOH and the proton donor are mixed at a temperature of 60°C for 5 min to obtain the alkaline solution; the mass-volume ratio of the KOH and the proton donor is 0.3 g:3 mL; the proton donor is ethylene glycol;

[0053] The mass-volume ratio of the Kevlar fibers, the alkaline solution and dimethyl sulfoxide is 0.5 g:3 mL:100 mL; the Kevlar fibers, the alkaline solution and dimethyl sulfoxide are uniformly mixed in a stirring device (a magnetic stirrer) at a stirring temperature of 60°C for a reaction time of 10 min;

[0054] (2) coating the aramid nanofiber dispersion on the surface of the porous base film layer under nitrogen protection, annealing at 130°C for 10 min, then immersing in a mixed solution for 10 min, washing with water and drying, and then placing in a magnetron sputtering device to obtain the composite coating; the mixed solution is a mixture of dimethyl sulfoxide and isopropyl alcohol, and the volume ratio of dimethyl sulfoxide to isopropyl alcohol is 0.2:1; in the magnetron sputtering device, the vacuum degree is adjusted to 10-4 Pa, the target material is copper, the plating power is 25W, and the time is 300s.

[0055] Example 2

[0056] Compared with Example 1, only the volume ratio of the mixed solution is different, specifically, the mixed solution is a mixture of dimethyl sulfoxide and isopropanol, and the volume ratio of dimethyl sulfoxide to isopropanol is 0.5:1.

[0057] Example 3

[0058] Compared with Example 1, only the power and time of the magnetron sputtering are different, specifically, the plating power is 100W, and the time is 75s.

[0059] Example 4

[0060] Compared with Example 1, only the power and time of the magnetron sputtering are different, specifically, the plating power is 10W, and the time is 750s.

[0061] Example 5

[0062] Compared with Example 1, only the power and time of the magnetron sputtering are different, specifically, the plating power is 200W, and the time is 37.5s.

[0063] Example 6

[0064] Compared with Example 1, only the soaking time is different, and the soaking time is 20min.

[0065] Example 7

[0066] Compared with Example 1, only the soaking time is different, and the soaking time is 5min.

[0067] Example 8

[0068] Compared with Example 1, only the annealing temperature is different, and the annealing temperature is 100℃ for 20min.

[0069] Example 9

[0070] Compared with Example 1, only the thickness of the base film layer is different, and the porous base film layer raw material is a polyethylene porous film with a pore size of 35nm, a porosity of 45±5%, and a thickness of 5±0.5μm (Gu Na Technology Co., Ltd. in Guangzhou).

[0071] Example 10

[0072] Compared with Example 1, only the composition of the alkaline solution is different, and it is a mixture of KOH and water.

[0073] Example 11

[0074] Compared with Example 1, only the target material is different, which is silver.

[0075] Example 12

[0076] Compared with Example 1, only the selection of aramid fiber is different, which is Nomex fiber, purchased from DuPont.

[0077] Example 13

[0078] Compared with Example 1, only the mass-volume ratio of aramid fiber, alkaline solution and organic solvent is different, which is 2g: 15mL: 100mL.

[0079] Example 14

[0080] Compared with Example 1, only the alkaline solution is a mixture of base and proton donor, and the mass-volume ratio of the base and the proton donor is different, which is 5g: 15mL;

[0081] Example 15

[0082] Compared with Example 1, only the thickness of the aramid nanofiber layer is different; by changing the amount of aramid nanofiber dispersion solution added during the coating process.

[0083] Example 16

[0084] Compared with Example 1, only the thickness of the rigid coating layer is different; by changing the magnetron sputtering time.

[0085] Comparative Examples 1-11

[0086] Comparative Example 1

[0087] Compared with Example 1, only the preparation process does not perform annealing treatment directly immersed in solution, as follows:

[0088] A composite coating layer, comprising a porous base film layer, an aramid nanofiber layer and a rigid coating layer arranged in sequence;

[0089] A preparation method of the composite coating layer, comprising the following steps:

[0090] (1) uniformly mix Kevlar fiber, alkaline solution and organic solvent to obtain aramid nanofiber dispersion solution;

[0091] Preparation of the alkaline solution: the alkaline solution is a mixture of KOH and proton donor, KOH and proton donor are mixed at a temperature of 60℃ for 5min, and uniformly mixed to obtain the alkaline solution; the mass-volume ratio of KOH and proton donor is 0.3g: 3mL; the proton donor is ethylene glycol;

[0092] The mass-volume ratio of the Kevlar fiber, alkaline solution, and dimethyl sulfoxide is 0.5 g:3 mL:100 mL; the Kevlar fiber, alkaline solution, and dimethyl sulfoxide are stirred and uniformly mixed in a stirring device (a magnetic stirrer), the stirring temperature is 60℃, and the reaction time is 10 min;

[0093] (2) The aramid nanofiber dispersion liquid is coated on the surface of the porous base film layer under nitrogen protection, then soaked in a mixed solution for 10 min, washed with water and dried, and then placed in a magnetron sputtering device to obtain the composite coating; the mixed solution is a mixture of dimethyl sulfoxide and isopropanol, and the volume ratio of dimethyl sulfoxide to isopropanol is 0.2:1; the raw material of the porous base film layer is a polyethylene porous film, the pore size is 40 nm, the porosity is 55±5%, and the thickness is 2.5±0.5 μm (Gu Na Technology Co., Ltd. in Guangzhou); in the magnetron sputtering device, the vacuum degree is adjusted to 10 -4 Pa, and the treatment is carried out in an argon atmosphere, the target material is copper, the plating power is 25 W, and the time is 300 s.

[0094] Comparative Example 2

[0095] Compared with Example 1, only the volume ratio of the mixed solution is different, specifically, the mixed solution is a mixture of dimethyl sulfoxide and isopropanol, and the volume ratio of dimethyl sulfoxide to isopropanol is 0.05:1.

[0096] Comparative Example 3

[0097] Compared with Example 1, only the mixed solution is a mixture of water and ethanol, and the volume ratio of water to ethanol is 0.2:1.

[0098] Comparative Example 4

[0099] Compared with Example 1, only the power and time of the magnetron sputtering are different, specifically, the plating power is 250 W, and the time is 30 s.

[0100] Comparative Example 5

[0101] Compared with Example 1, the annealing temperature and time are different, specifically, annealing at 80℃ for 20 min.

[0102] Comparative Example 6

[0103] Compared with Example 1, only the preparation process does not perform soaking treatment, specifically as follows:

[0104] A composite coating, comprising a porous base film layer, an aramid nanofiber layer, and a rigid coating layer arranged in sequence;

[0105] A preparation method of the composite coating, comprising the following steps:

[0106] (1) Kevlar fiber, alkaline solution, organic solvent were mixed uniformly to obtain aramid nanofiber dispersion liquid;

[0107] The preparation of the alkaline solution: the alkaline solution was a mixture of KOH and a proton donor, KOH and the proton donor were mixed at a temperature of 60°C for 5 min, and were mixed uniformly to obtain the alkaline solution; the mass-volume ratio of KOH and the proton donor was 0.3 g:3 mL; the proton donor was ethylene glycol;

[0108] The mass-volume ratio of the Kevlar fiber, the alkaline solution, and dimethyl sulfoxide was 0.5 g:3 mL:100 mL; the Kevlar fiber, the alkaline solution, and dimethyl sulfoxide were mixed uniformly in a stirring device (a magnetic stirrer), the stirring temperature was 60°C, and the reaction time was 10 min;

[0109] (2) Under the protection of nitrogen, the aramid nanofiber dispersion liquid was coated on the surface of the porous base film layer, annealed at 130°C for 10 min, and then placed in a magnetron sputtering device after water washing and drying to obtain the composite coating; the raw material of the porous base film layer was a polyethylene porous film, the pore size was 40 nm, the porosity was 55±5%, and the thickness was 2.5±0.5 μm (Gu Na Technology Co., Ltd. in Guangzhou); in the magnetron sputtering device, the vacuum degree was adjusted to 10 -4 Pa, processing was carried out in an argon atmosphere, the target material was copper, the film plating power was 25 W, and the time was 300 s.

[0110] Comparative Example 7

[0111] Compared with Example 1, no aramid nanofiber layer was contained, and the specific process was as follows: a polyethylene porous film was placed in a magnetron sputtering device, the vacuum degree was adjusted to 10 -4 Pa, processing was carried out in an argon atmosphere to obtain the composite coating; the target material was copper, the film plating power was 25 W, the time was 300 s; the raw material of the porous base film layer was a polyethylene porous film, the pore size was 40 nm, the porosity was 55±5%, and the thickness was 2.5±0.5 μm (Gu Na Technology Co., Ltd. in Guangzhou).

[0112] Comparative Example 8

[0113] Compared with Example 1, no aramid nanofiber layer was contained, and the specific process was as follows: a polyethylene porous film was placed in a magnetron sputtering device, the vacuum degree was adjusted to 10 -4 Pa, processing was carried out in an argon atmosphere to obtain the composite coating; the target material was copper, the film plating power was 100 W, the time was 75 s; the raw material of the porous base film layer was a polyethylene porous film, the pore size was 40 nm, the porosity was 55±5%, and the thickness was 2.5±0.5 μm (Gu Na Technology Co., Ltd. in Guangzhou).

[0114] Comparative Example 9

[0115] Compared with Example 1, the thickness of aramid nanofiber layer is different; by changing the addition amount of aramid nanofiber dispersion liquid in the coating process.

[0116] Comparative Example 10

[0117] Compared with Example 1, the thickness of rigid coating is different; by changing the magnetron sputtering time.

[0118] Comparative Example 11

[0119] Compared with Example 1, the thickness of rigid coating is different; by changing the magnetron sputtering time.

[0120] The structure parameters of aramid nanofiber layer and rigid coating in the composite coating prepared by the examples and comparative examples are shown in Table 1, wherein the fiber diameter and pore size are tested by SEM; the porosity is determined by simple weight method, and is calculated according to the thickness and density of the corresponding material layer, wherein the fiber diameter and pore size are average values.

[0121] The thickness is tested by a Malvern thickness tester.

[0122] Table 1

[0123]

[0124]

[0125]

[0126] Performance test

[0127] (1) The peeling force test of the composite coating material prepared by the examples and comparative examples was carried out: a tensile testing machine was used for testing, a test sample with a size of 15x100mm was taken, the adhesive tape was pasted on the stainless steel plate, then the test sample was evenly pasted on the double-sided adhesive tape, a 1kg standard small pressure roller was used to press back and forth for 3 times, then the adhesive tape was pasted on the surface of the sample, a 1kg standard small pressure roller was used to press back and forth for 3 times, then the pressed sample was taken to the tensile testing machine for 180° stretching, the speed was 100mm / min, and the maximum value was taken as the result. 。

[0128] (2) Resistance test of the composite coating material prepared in the examples and comparative examples: using a flexible electronic tester, a test sample with a size of 10*30mm is taken, and the two ends of the test sample are fixed on the two sides of the flexible electronic tester folding test fixture with adhesive tape. The flexible electronic tester folding parameters are set as initial angle 0°, folding angle 180°, folding rate 40° / s, folding times 10,000 times, 1,000,000 times, and folding radius 0.3mm. After folding, the resistance of the sample is tested by using a milliohm meter, and the maximum value is taken as the result.

[0129] The test results are shown in Table 2.

[0130] Table 2

[0131]

[0132]

[0133] As shown in the above table, the composite coating provided by the application can effectively improve the interfacial bonding force between the rigid coating and the flexible base film layer, thereby solving the problems of interfacial separation in the dynamic deformation process and meeting the application requirements of flexible electronic devices. Figure 1 The scanning electron microscope image of the composite coating prepared in Example 1 shows that the metal particles are coated on the aramid nanofiber to form stable deposition, realizing a fibrous conductive network structure, so that the material has a stable gradient mechanical interface, thereby maintaining excellent conductive performance under extreme dynamic mechanical behavior.

[0134] Because the magnetron sputtering power is too large, the kinetic energy of high-energy particles is converted into heat energy, resulting in the rupture of the composite coating prepared in Comparative Example 4, and no subsequent test is performed.

[0135] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the application and not to limit the protection scope of the application. Although the application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the application.

Claims

1. A composite coating, characterized in that, The device comprises a porous base film layer, an aramid nanofiber layer, and a rigid coating arranged sequentially; the porous base film layer is a porous base film layer with a porous structure formed of polyolefin fibers; the aramid nanofiber layer is an aramid nanofiber layer with a porous structure formed of aramid nanofibers; the rigid coating is composed of at least one of copper, aluminum, platinum, gold, silver, titanium, molybdenum, silicon, alumina, indium tin oxide, silicon oxide, and titanium oxide. The method for preparing the composite coating includes the following steps: S1. Mix aramid fibers, alkaline solution, and organic solvent evenly to obtain an aramid nanofiber dispersion; S2. Aramid nanofiber dispersion is coated on the surface of a porous base film. After annealing, it is immersed in a mixed solution for 5-30 minutes. After washing and drying, it is placed in a magnetron sputtering device to obtain the composite coating. The annealing temperature is 100-130℃, and the annealing time is 10-20 min; The mixed solution is a mixture of dimethyl sulfoxide and isopropanol, with a volume ratio of dimethyl sulfoxide to isopropanol of (0.1-0.5):1; The target material for magnetron sputtering is at least one of copper, aluminum, platinum, gold, silver, titanium, molybdenum, silicon, aluminum oxide, indium tin oxide, silicon oxide, and titanium oxide.

2. The composite coating as described in claim 1, characterized in that, The thickness of the porous base film is 0.1-10 μm, the pore size of the porous base film is 20-80 nm, and the porosity is 30-60%; the diameter of the polyolefin fiber is 30-60 nm. And / or, the thickness of the aramid nanofiber layer is ≥0.05μm, the pore size of the aramid nanofiber layer is 20-80nm, the porosity is 10-50%; the diameter of the aramid nanofiber is 10-50nm; And / or, the thickness of the rigid coating is 0.01-1 μm.

3. The composite coating as described in claim 2, characterized in that, The porous base membrane has a pore size of 30-40 nm and a porosity of 35-50%; the polyolefin fiber has a diameter of 45-55 nm.

4. The composite coating as described in claim 2, characterized in that, The aramid nanofiber layer has a pore size of 30-50 nm and a porosity of 30-40%; the aramid nanofiber has a diameter of 20-30 nm.

5. The composite coating as described in claim 1, characterized in that, In step S1, at least one of the following (1)-(4) is satisfied: (1) The aramid fiber is para-aramid fiber or meta-aramid fiber; (2) The mass-to-volume ratio of the aramid fiber, alkaline solution, and organic solvent is (0.1-2) g: (3-20) mL: 100 mL; (3) The alkaline solution is a mixture of base and proton donor, and the mass-to-volume ratio of base to proton donor is (0.1-10) g: (2-20) mL; (4) The organic solvent is at least one of dimethyl sulfoxide and dimethyl fumarate.

6. The composite coating as described in claim 5, characterized in that, The base is at least one of sodium hydroxide and potassium hydroxide; the proton donor is at least one of water, ethanol, isopropanol, ethylene glycol, propylene glycol, and butanediol.

7. The composite coating as described in claim 1, characterized in that, The soaking time is 10-20 minutes.

8. The composite coating as described in claim 1, characterized in that, The vacuum level of the magnetron sputtering is 10. -4 Pa, the coating power of magnetron sputtering is 5-200W, and the magnetron sputtering time is 20-1500s.

9. The composite coating as described in claim 8, characterized in that, The magnetron sputtering deposition power is 25-100W, and the magnetron sputtering time is 50-300s.

10. The application of the composite coating as described in any one of claims 1-9 in the fabrication of flexible electronic devices.

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