Polyimide composite membrane and preparation method therefor

Abstract

The present application relates to the technical field of polymer membranes. Disclosed are a polyimide composite membrane and a preparation method therefor. The polyimide composite membrane comprises a polyimide base membrane and a coating; the polyimide base membrane is a polyimide fiber membrane; the polyimide fiber membrane comprises a plurality of stacked polyimide fibers; the surfaces of the polyimide fibers are coated with the coating; the material of the coating comprises a polymer material having low surface tension.

Description

Polyimide composite film and preparation method thereof

[0001] This application claims priority to the Chinese patent application No. 202410463132.1, filed on April 17, 2024, to the Chinese Patent Office, the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of polymer film, in particular to a polyimide composite film and a preparation method thereof. BACKGROUND

[0003] The electrospun polyimide fiber film is an extremely fine fiber film with a size ranging from microns to nanometers, which is prepared by an electrospinning process. The main body of the electrospun polyimide fiber film is composed of a large number of stacked fibers, and there are a large number of pores between the fibers, which can be used as a waterproof and breathable film in the waterproof field. However, the current polyimide fiber film often has a waterproof failure problem during use.

[0004] The above content is only used to assist in understanding the technical solutions of the present application, and does not represent the acknowledgement of the above content as prior art. TECHNICAL PROBLEM

[0005] The main purpose of the present application is to provide a polyimide composite film and a preparation method thereof, in order to solve the waterproof failure problem of the current polyimide fiber film during use. TECHNICAL SOLUTION

[0006] In order to achieve the purpose of the present application, the present application provides a polyimide composite film, which comprises a polyimide base film and a coating layer. The polyimide base film is a polyimide fiber film, which comprises a plurality of stacked polyimide fibers. The coating layer is coated on the surface of the polyimide fiber, and the material of the coating layer comprises a polymer material with low surface tension.

[0007] In an embodiment, the polymer material is an organic silicon-based polymer material, and the material of the coating layer further comprises a crosslinking agent.

[0008] In an embodiment, the molecular weight of the organic silicon-based polymer material is less than 1 million; and / or,

[0009] The organic silicon-based polymer material is at least one of polymethyl vinyl siloxane and polymethyl trifluoropropyl siloxane; and / or,

[0010] The crosslinking agent is at least one of hydrogen-containing silicone oil, tetraethyl orthosilicate and n-butyl titanate.

[0011] In an embodiment, the thickness of the coating layer ranges from 0.01 to 2 microns.

[0012] In an embodiment, the weight ratio of the polymer material to the polyimide-based film is (0.1-30): 100.

[0013] The application also provides a preparation method of the polyimide composite film as described above, comprising the following steps:

[0014] Step S1, providing a polyimide fiber film and a polymer material with low surface tension;

[0015] Step S2, coating the polymer material with low surface tension on the surface of the polyimide fiber film in the form of a coating layer to obtain the polyimide composite film.

[0016] In an embodiment, step S2 comprises:

[0017] Any one of the immersion method, the plasma treatment method, the chemical vapor deposition method and the spraying method is adopted to coat the polymer material with low surface tension on the surface of the polyimide fiber film in the form of a coating layer to obtain the polyimide composite film.

[0018] In an embodiment, the polymer material is an organic silicon-based polymer, and step S2 comprises the following steps:

[0019] Step S21, dispersing the organic silicon-based polymer material and a cross-linking agent in an organic solvent, and obtaining a polymer solution after stirring and mixing;

[0020] Step S22, passing the polyimide fiber film through the polymer solution at a preset speed, and obtaining the polyimide composite film after drying.

[0021] In an embodiment, in step S21, the concentration of the polymer solution ranges from 2wt% to 4wt%; and / or, in step S22, the preset speed ranges from 0.4m / min to 0.6m / min.

[0022] In an embodiment, in step S21, further comprising: adding a catalyst to the organic solvent, the catalyst being at least one of a platinum-based catalyst, a palladium-based catalyst, a nickel-based catalyst and a tin-based catalyst. Advantages

[0023] The polyimide composite film provided by the application comprises a polyimide base film and a coating layer, the polyimide base film is a polyimide fiber film, the polyimide fiber film comprises a plurality of polyimide fibers stacked, and the coating layer is coated on the surface of the polyimide fiber, and the material of the coating layer comprises a polymer material with low surface tension. Since the surface of the polyimide fiber is coated with the polymer material with low surface tension, the surface tension of the polyimide composite film can be effectively reduced, so that the polyimide composite film has good waterproof performance, thereby effectively ensuring that the polyimide composite film is not prone to waterproof failure during use. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only constitute some embodiments of the application, and for those skilled in the art, other related drawings can also be obtained based on these drawings without creative labor.

[0025] Fig. 1 is a schematic view of a polyimide fiber film in a polyimide composite film provided by the application;

[0026] Fig. 2 is a schematic view of a polyimide composite film provided by the application;

[0027] Fig. 3 is a schematic view of an embodiment of a preparation process of a polyimide composite film provided by the application.

[0028] Explanation of reference numerals:

[0029] 1, polyimide fiber; 2, coating layer;

[0030] 100, polyimide fiber film; 200, polyimide composite film; 300, unwinding device; 400, polymer solution tank; 500, drying furnace; 600, winding device.

[0031] The implementation, functional characteristics and advantages of the application will be further described with reference to the embodiments and the accompanying drawings. Embodiment of the application

[0032] It should be understood that the specific embodiments described herein are only used to explain the application and not to limit the application.

[0033] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. If the specific conditions are not indicated in the embodiments, the conventional conditions or the conditions recommended by the manufacturers are adopted. If the manufacturers of the reagents or instruments are not indicated, the conventional products that can be purchased in the market are adopted. In addition, the meaning of "and / or" appearing in the whole text includes three parallel solutions. For example, "A and / or B" includes the A solution, or the B solution, or the solution in which A and B are satisfied at the same time. In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the fact that the technical solutions can be realized by the ordinary skilled in the art. When the combination of the technical solutions appears to be contradictory or unachievable, it should be considered that the combination of the technical solutions does not exist and is not within the protection scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by the ordinary skilled in the art without creative labor are within the protection scope of the present application.

[0034] In order to solve the waterproof failure problem of the polyimide fiber membrane 100 in the use process, the present application provides a polyimide composite membrane 200 with good waterproof performance.

[0035] As shown in FIG. 1 and FIG. 2, the polyimide composite membrane 200 provided by the present application includes a polyimide base membrane and a coating layer 2. The polyimide base membrane is a polyimide fiber membrane 100, the polyimide fiber membrane 100 includes a plurality of stacked polyimide fibers 1, and the coating layer 2 is coated on the surface of the polyimide fiber 1. The material of the coating layer 2 includes a polymer material with low surface tension.

[0036] In the embodiments of the present application, the polyimide fiber membrane 100 is an electrospun polyimide fiber membrane 100, the main body of the membrane is composed of a large number of stacked polyimide fibers 1, the surface of the polyimide fiber 1 is coated with a coating layer 2, the material of the coating layer 2 includes a polymer material with low surface tension, and the polymer material with low surface tension is one or a mixture of several of paraffin polymer material, pyridine derivative polymer material, stearic acid polymer material, organic silicon polymer material and organic fluorine polymer material.

[0037] Since the surface of the polyimide fiber 1 in the polyimide fiber membrane 100 is coated with a polymer material with low surface tension, the surface tension of the polyimide composite membrane 200 can be effectively reduced, so that the polyimide composite membrane 200 has good waterproof performance, thereby ensuring that the polyimide composite membrane 200 does not easily appear waterproof failure problem in the use process.

[0038] In the specific embodiments of the present application, the polymer material is a silicone-based polymer material, and the material of the coating layer 2 further comprises a cross-linking agent. In this embodiment, the material of the coating layer 2 comprises a silicone-based polymer material and a cross-linking agent, and the silicone-based polymer material is combined with the surface of the polyimide fiber 1 in the polyimide-based film through the cross-linking agent, and the binding force is relatively firm, so that the polyimide composite film 200 has good mechanical properties such as wear resistance and tensile strength, thereby ensuring that the polyimide composite film 200 does not easily appear waterproof failure problem in the long-term use process.

[0039] In the embodiments of the present application, the molecular weight of the silicone-based polymer material is less than 1 million, that is, the organic polymer material is silicone gum, and the silicone gum is cross-linked and coated on the surface of the polyimide fiber through chemical reaction under the action of the cross-linking agent, thereby obtaining the polyimide composite film 200.

[0040] The silicone-based polymer material is at least one of polymethyl vinyl siloxane and polymethyl trifluoropropyl siloxane; and the cross-linking agent is one of hydrogen-containing silicone oil, ethyl orthosilicate, and n-butyl titanate. It should be noted that when the silicone-based polymer material is selected as polymethyl vinyl siloxane, the cross-linking agent is selected as hydrogen-containing silicone oil; and when the silicone-based polymer material is selected as polymethyl trifluoropropyl siloxane, the cross-linking agent is selected as ethyl orthosilicate and / or n-butyl titanate.

[0041] In the embodiments of the present application, the thickness of the coating layer 2 ranges from 0.01 to 2 μm (such as 0.01 μm, 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, and interval values between any two endpoint values). The coating layer 2 with the above thickness range can not only make the polyimide composite film 200 have good waterproof performance, but also reduce the production cost to a certain extent.

[0042] In the embodiments of the present application, the weight ratio of the polymer material to the polyimide-based film is (0.1-30):100, such as 0.1:100, 0.5:100, 1:100, 10:100, 20:100, 30:100, and interval values between any two endpoint values. The above weight ratio can not only achieve good waterproof performance of the polyimide composite film 200, but also ensure good air permeability of the polyimide composite film 200. If the weight ratio of the two is less than 0.1:100, the waterproof performance cannot be significantly improved, and if the weight ratio of the two is greater than 30:100, although the waterproof performance is improved, it will cause some pores of the polyimide composite film 200 to be blocked, and the air permeability of the film will be poor.

[0043] The present application also provides a preparation method of the polyimide composite film 200 as described above, which comprises the following steps:

[0044] Step S1, providing a polyimide fiber membrane 100 and a polymer material with low surface tension.

[0045] In specific embodiments of the present application, the polyimide fiber membrane 100 is an electrospun polyimide fiber membrane 100, and the polymer material is one or a mixture of several of paraffin-based polymer materials, pyridine derivative-based polymer materials, stearic acid polymer materials, silicone-based polymer materials, and organic fluorine-based polymer materials.

[0046] Step S2, coating the surface of the polyimide fiber in the polyimide fiber membrane 100 with the polymer material with low surface tension in the form of coating layer 2 to obtain a polyimide composite membrane 200.

[0047] In specific embodiments of the present application, any of the immersion method, plasma treatment method, chemical vapor deposition method, and spraying method can be used to wrap the surface of the polyimide fiber 1 in the polyimide fiber membrane 100 with the polymer material with low surface tension in the form of coating layer 2 to obtain the polyimide composite membrane 200.

[0048] The immersion method specifically includes: dispersing the polymer material with low surface tension in an organic solvent to obtain a polymer solution, immersing the polyimide fiber membrane 100 in the polymer solution, coating the surface of the polyimide fiber 1 in the polyimide fiber membrane 100 with the polymer material after immersion, and then drying to obtain the polyimide composite membrane 200. The specific operation conditions are not limited, as long as the weight ratio of the polymer material to the polyimide fiber membrane 100 in the polyimide composite membrane 200 satisfies (0.1-30):100, which is within the scope of the present application.

[0049] The plasma treatment method specifically includes: ionizing the polymer material with low surface tension into a plasma state through a plasma device and uniformly distributing it on the surface of the polyimide fiber 1 in the polyimide fiber membrane 100 to obtain the polyimide composite membrane 200. The specific operation conditions are not limited, as long as the thickness of the coating layer 2 in the polyimide composite membrane 200 satisfies 0.01-2 μm, which is within the scope of the present application.

[0050] The chemical vapor deposition method specifically includes: depositing the polymer material with low surface tension in the form of a gas on the surface of the polyimide fiber 1 in the polyimide fiber membrane 100 to completely coat the surface of the polyimide fiber 1 with the polymer, thereby obtaining the polyimide composite membrane 200. The specific operation conditions are not limited, as long as the thickness of the coating layer 2 in the polyimide composite membrane 200 satisfies 0.01-2 μm, which is within the scope of the present application.

[0051] The spraying method is specifically as follows: a polymer material with low surface tension is atomized and then sprayed onto the surface of the polyimide fibers 1 in the polyimide fiber film 100, to obtain the polyimide composite film 200. The specific operation conditions are not limited, as long as the weight ratio of the polymer material to the polyimide fiber film 100 in the polyimide composite film 200 satisfies (0.1-30): 100, which is within the scope of the present application.

[0052] In the embodiments of the present application, the polymer material is a silicone-based polymer, and step S2 includes the following steps:

[0053] In step S21, the silicone-based polymer material and the crosslinking agent are dispersed in an organic solvent, and after stirring and mixing, a polymer solution is obtained.

[0054] Specifically, the silicone-based polymer material is at least one of polymethyl vinyl siloxane and polymethyl trifluoropropyl siloxane, the crosslinking agent is at least one of hydrogen-containing silicone oil, tetraethyl orthosilicate, and n-butyl titanate, and the organic solvent is at least one of cyclohexane, ethanol, toluene, and carbon tetrachloride.

[0055] The concentration of the polymer material is controlled within the range of 2-4 wt%, such as 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, and interval values between any two end point values. The silicone-based polymer material with the above concentration range can not only achieve better waterproof performance of the polyimide composite film 200, but also ensure good air permeability of the polyimide composite film 200. If the concentration of the silicone-based polymer material is less than 2 wt%, its waterproof performance cannot be significantly improved. If the concentration of the silicone-based polymer material is greater than 4 wt%, although the waterproof performance is improved, it will cause some pores of the polyimide composite film 200 to be blocked, and the air permeability of the film will be poor.

[0056] In step S22, the polyimide fiber film 100 is passed through the polymer solution at a preset speed, and after drying, the polyimide composite film 200 is obtained.

[0057] Referring to FIG. 3, specifically, the polymer solution tank 400 containing the polymer solution and the drying furnace 500 are sequentially and spacedly arranged between the unwinding device 300 of the electrospun polyimide fiber membrane 100 roll stock and the winding device 600, the advancing speed of the electrospun polyimide fiber membrane 100 is controlled, the polymer solution passes at a preset speed, and then the drying operation is performed by the 5m-long drying furnace 500, and the winding is performed on the winding device 600 side to obtain the polyimide composite membrane 200 roll stock. The unwinding device 300 and the winding device 600 generally include an unwinding roller and a winding roller, and the specific structure can refer to the prior art, which will not be repeated here. It should be noted that the polymer solution tank 400 is provided with a plurality of guide members (such as guide rollers) at intervals, so that the guided electrospun polyimide fiber membrane 100 roll stock is immersed in the polymer solution tank 400 and contacts the polymer solution, thereby facilitating the coating of the polymeric material on the surface of the polyimide fiber.

[0058] The advancing speed of the electrospun polyimide fiber membrane 100 affects the soaking time of the electrospun polyimide fiber membrane 100 in the polymer solution, and further affects the waterproof performance. In an embodiment, the advancing speed (i.e., the preset speed) of the electrospun polyimide fiber membrane 100 is 0.4-0.6 m / min (such as 0.4 m / min, 0.5 m / min, 0.6 m / min, and any interval value between any two endpoint values). If the advancing speed is greater than 0.6 m / min, the soaking time of the electrospun polyimide fiber membrane 100 in the polymer solution is short, and the drying time is short, the amount of silicone-based polymer coated on the surface of the electrospun polyimide fiber membrane 100 is small, and the waterproof performance is not obviously improved. If the advancing speed is less than 0.4 m / min, the soaking time of the electrospun polyimide fiber membrane 100 in the polymer solution is long, and the amount of silicone-based polymer coated on the surface of the electrospun polyimide fiber membrane 100 is large, and the air permeability of the membrane is poor.

[0059] Further, in order to accelerate the chemical reaction rate of the silicone-based polymer under the action of the crosslinking agent, in the embodiment of the present application, step S21 further includes: adding a catalyst to the organic solvent, the catalyst being at least one of a platinum catalyst, a palladium catalyst, a nickel catalyst, and a tin catalyst. It should be noted that the platinum catalyst, the palladium catalyst, the nickel catalyst, and the tin catalyst can be an organic catalyst or an inorganic catalyst. When the silicone-based polymer material is selected as polymethylvinylsiloxane, the catalyst is at least one of a platinum catalyst, a palladium catalyst, and a nickel catalyst. When the silicone-based polymer material is selected as polymethyltrifluoropropylsiloxane, the catalyst is a tin catalyst, specifically, dibutyltin dilaurate.

[0060] In an embodiment, the concentration of the catalyst in the total amount of the organic solvent is 1-100 ppm (such as 1 ppm, 10 ppm, 50 ppm, 100 ppm, and interval values between any two endpoint values), so that both the reaction rate can be accelerated and the cost can be reduced to a certain extent.

[0061] The polyimide composite film and the preparation method thereof will be described in detail below through specific embodiments. It should be noted that the polyimide fiber membranes used in the following examples and comparative examples are the same batch of electrospun polyimide fiber membranes, and their properties are basically the same.

[0062] Example 1

[0063] The polyimide composite film of the present embodiment is prepared by the following steps:

[0064] (1) At room temperature, polymethylvinylsiloxane and hydrogen-containing silicone oil are dispersed in cyclohexane at a mass ratio of 100:2, the concentration of polymethylvinylsiloxane is controlled to be 2wt%, and a chloroplatinic acid catalyst with a concentration of 5 ppm is added, stirred for 0.5 h to make it uniformly dispersed, to obtain a polymer solution, and the polymer solution is poured into a polymer solution tank. The molecular weight of the polymethylvinylsiloxane is 600,000 to 700,000.

[0065] (2) Place the roll stock of the electrospun polyimide fiber membrane on the unwinding device as shown in Figure 3, control the electrospun polyimide fiber membrane to pass through the polymer solution at a forward rate of 0.5 m / min, and perform drying operation at 180℃ in the drying oven to make the solvent volatilize and the silicone crosslink and solidify to form a coating, and then roll up through the winding device to obtain the roll stock of the polyimide composite film.

[0066] Example 2

[0067] The difference between the present embodiment and Example 1 is only that the concentration of polymethylvinylsiloxane is 3wt%, and the other operations are the same as those in Example 1.

[0068] Example 3

[0069] The difference between the present embodiment and Example 1 is only that the concentration of polymethylvinylsiloxane is 4wt%, and the other operations are the same as those in Example 1.

[0070] Example 4

[0071] The difference between the present embodiment and Example 1 is only that the electrospun polyimide fiber membrane passes through the polymer solution at a forward rate of 0.4 m / min, and the other operations are the same as those in Example 1.

[0072] Example 5

[0073] The present example differs from Example 1 only in that the electrospun polyimide fiber membrane is passed through the polymer solution at a forward rate of 0.6 m / min, and the other operations are the same as in Example 1.

[0074] Comparative Example 1

[0075] The present comparative example differs from Example 1 only in that the concentration of polymethylvinylsiloxane is 0.1 wt%, and the other operations are the same as in Example 1.

[0076] Comparative Example 2

[0077] The present comparative example differs from Example 1 only in that the concentration of polymethylvinylsiloxane is 5 wt%, and the other operations are the same as in Example 1.

[0078] Comparative Example 3

[0079] The present comparative example differs from Example 1 only in that the concentration of polymethylvinylsiloxane is 10 wt%, and the other operations are the same as in Example 1.

[0080] Comparative Example 4

[0081] The present comparative example differs from Example 1 only in that the electrospun polyimide fiber membrane is passed through the polymer solution at a forward rate of 1 m / min, and the other operations are the same as in Example 1. The other operations are the same as in Example 1.

[0082] Comparative Example 5

[0083] The present comparative example differs from Example 1 only in that the electrospun polyimide fiber membrane is passed through the polymer solution at a forward rate of 0.1 m / min, and the other operations are the same as in Example 1. The other operations are the same as in Example 1.

[0084] The polyimide composite membranes obtained in Examples 1 to 5 and Comparative Examples 1 to 5 are subjected to performance tests, and the base membrane electrospun polyimide fiber membrane is also subjected to corresponding performance tests, and the performance test results are shown in Table 1.

[0085] Table 1 Performance data of electrospun polyimide fiber membranes, polyimide composite membranes obtained in Examples 1 to 5 and Comparative Examples 1 to 5.

[0086] Silicone content, wt% Surface mass, g / m2 Tensile strength, MPa Air permeability (7KPa, 2x2cm), ml / min Contact angle with water, ° Contact angle with white oil, ° Electrospun polyimide fiber membrane 0 5.3 30 300 128 0 Example 1 5.3 6.1 33 240 145 105 Example 2 6.2 6.3 34 230 148 107 Example 3 6.9 6.7 35 220 151 108 Example 4 5.5 6.2 34 238 146 106 Example 5 5.1 5.8 31 242 143 102 Comparative Example 1 0.8 5.4 30 300 129 0 Comparative Example 2 23 6.9 35 60 146 106 Comparative Example 3 28.8 39 0 15 211 10 Comparative Example 4 7.6 5.7 32 280 140 101 Comparative Example 5 26 7.1 36 101 50 109

[0087] As can be seen from the performance data in Table 1, compared with the original electrospun polyimide fiber membrane, the polyimide composite membranes of Examples 1 to 3 and Examples 1, 4 to 5 can have good tensile strength, air permeability, hydrophobicity and oleophobicity by adjusting the concentration of the organosilicon polymer (polymethylvinylsiloxane) and the forward rate of the electrospun polyimide fiber membrane, respectively.

[0088] As can be seen from the comparison of Comparative Example 1, Example 1 and the original electrospun polyimide fiber membrane, the hydrophobicity of the organosilicon polymer (polymethylvinylsiloxane) is not improved substantially when the concentration of the organosilicon polymer (polymethylvinylsiloxane) is too small, and the organosilicon polymer (polymethylvinylsiloxane) is relatively oleophilic.

[0089] As can be seen from the comparison of Comparative Examples 2 to 3, Example 1 and the original electrospun polyimide fiber membrane, the hydrophobicity of the organosilicon polymer (polymethylvinylsiloxane) is greatly improved when the concentration of the organosilicon polymer (polymethylvinylsiloxane) is too large, but the air permeability is poor, especially when the concentration of the organosilicon polymer (polymethylvinylsiloxane) is 10 wt%, the air permeability is reduced to zero.

[0090] As can be seen from the comparison of Comparative Example 4, Example 1 and the original electrospun polyimide fiber membrane, when the forward rate of the electrospun polyimide fiber membrane is too large, the immersion time of the electrospun polyimide fiber membrane in the polymer solution is relatively short, and the drying time is also relatively short, so the hydrophobicity is slightly lower than that of Example 1.

[0091] As can be seen from the comparison of Comparative Example 5, Example 1 and the original electrospun polyimide fiber membrane, when the forward rate of the electrospun polyimide fiber membrane is too small, the immersion time of the electrospun polyimide fiber membrane in the polymer solution is relatively long, so the amount of the polymer coated on the surface of the polyimide fiber is relatively large, the hydrophobicity is improved, but the air permeability is poor.

[0092] It is to be noted that, as used in this specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component" can include a combination of two or more components, and the term "the item" can include multiple items unless the context clearly indicates otherwise.

[0093] The above merely illustrates the embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent items or equivalent process transformations, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A polyimide composite film, wherein, The polyimide composite film comprises a polyimide base film and a coating layer, the polyimide base film is a polyimide fiber film, the polyimide fiber film comprises a plurality of polyimide fibers stacked, and the coating layer is coated on the surface of the polyimide fiber, and the material of the coating layer comprises a polymer material with low surface tension.

2. The polyimide composite film of claim 1, wherein, The polymer material is an organic silicon-based polymer material, and the material of the coating layer further comprises a cross-linking agent.

3. The polyimide composite film of claim 2, wherein, The molecular weight of the organic silicon-based polymer material is less than 1 million; and / or, The organic silicon-based polymer material is at least one of polymethyl vinyl siloxane and polymethyl trifluoropropyl siloxane; and / or, The cross-linking agent is at least one of hydrogen-containing silicone oil, ethyl orthosilicate, and n-butyl titanate.

4. The polyimide composite film of claim 1, wherein, The thickness of the coating layer ranges from 0.01 to 2 microns.

5. The polyimide composite film according to any one of claims 1 to 4, wherein, The weight ratio of the polymer material to the polyimide base film is (0.1-30):

100.

6. A method for producing the polyimide composite film according to any one of claims 1 to 5, wherein, The preparation method comprises the following steps: Step S1, providing a polyimide fiber film and a polymer material with low surface tension; Step S2, coating the polymer material with low surface tension on the surface of the polyimide fiber film in the form of a coating layer to obtain the polyimide composite film.

7. The method for preparing a polyimide composite film according to claim 6, wherein, Step S2 comprises: Any one of the immersion method, the plasma treatment method, the chemical vapor deposition method and the spraying method is used to coat the polymer material with low surface tension on the surface of the polyimide fiber film in the form of a coating layer to obtain the polyimide composite film.

8. The method for preparing a polyimide composite film according to claim 7, wherein, The polymer material is an organic silicon-based polymer, and step S2 comprises the following steps: Step S21, dispersing the organic silicon-based polymer material and the cross-linking agent in an organic solvent, and stirring and mixing to obtain a polymer solution; Step S22, passing the polyimide fiber film through the polymer solution at a preset speed, and after drying, obtaining the polyimide composite film.

9. The method for preparing a polyimide composite film according to claim 8, wherein, In step S21, the concentration of the polymer solution ranges from 2 to 4 wt%; and / or, In step S22, the preset speed is 0.4-0.6 m / min.

10. The method of producing a polyimide composite film according to claim 8, wherein, In step S21, further comprising: adding a catalyst to the organic solvent, and the catalyst is at least one of a platinum-based catalyst, a palladium-based catalyst, a nickel-based catalyst, and a tin-based catalyst.

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