Anti-atomic oxygen black flexible film and preparation method and application thereof

Abstract

The invention relates to an anti-atomic oxygen black flexible film as well as a preparation method and application thereof. The anti-atomic oxygen black flexible film comprises a black flexible substrate and a non-compact laminated structure coating which is formed on the surface of the black flexible substrate and formed by crosslinking at least one of hydrotalcite nanosheets or hydrotalcite-like nanosheets with a silane coupling agent, the black flexible substrate comprises a black polyimide film, a black polyester film, a black polyethylene film and the like; preferably, the solar absorptivity alpha s of the black flexible substrate is larger than or equal to 0.88, and the hemispherical emissivity epsilon H of the black flexible substrate is larger than or equal to 0.78.

Description

Technical Field

[0001] The invention relates to an anti-ion oxygen black flexible film and a preparation method and application thereof, which is mainly applied to a thermal control system of a spacecraft and belongs to the technical field of aerospace material application. Background Art

[0002] Polymer materials have the advantages of good flexibility, light weight, low cost, and easy processing, and are an important component of aerospace materials. Black flexible films with high solar absorption ratios have good light-shielding properties and can be used as stray light absorbing materials. For example, polyimide polymer materials have outstanding comprehensive performance, and different types of polyimides have their own special performance advantages. They are widely used in spacecraft thermal control, power supply, and structural systems. Among them, the black composite film obtained by carbon doping of polyimide film has good light-shielding properties and can be used as electronic materials, electromagnetic interference elimination materials, and stray light absorbing materials. It is also a space material that has received widespread attention in recent years. Its high solar absorption ratio characteristics can be used in spacecraft thermal control systems and structural systems. However, during space flight, due to the effects of ultraviolet radiation, charged particle radiation, atomic oxygen and other space environments, the thermal radiation performance of black polyimide film will change, causing the thermal control system to deviate from the original set indicators. Especially when used in low-orbit space environments, when atomic oxygen collides with high-speed spacecraft in orbit, the bombardment energy of atomic oxygen can reach 4 to 5 eV. When atomic oxygen with high energy and strong oxidizing properties acts on the surface of polymer materials, it is easy to corrode. Conventional black polyimide films used on the surface of low-orbit spacecraft will be severely corroded and can be completely etched away after serving in low orbit for a few months. In addition, the current solar absorption ratio of black polyimide films is usually around 0.92. With the development of spacecraft, the demand for improving the solar absorption ratio of black flexible films has been further proposed. Summary of the invention

[0003] In order to solve the above problems, the present invention utilizes the fact that the black flexible film substrate itself contains highly absorbing components and has the solar absorption characteristics of a solar absorption ratio of αs≥0.90, and combines it with a material system that is stable in the space environment and has a low refractive index to simultaneously achieve high space environment stability and increase the solar absorption ratio of the black polyimide film through surface modification.

[0004] In one aspect, the present invention provides an anti-proton oxygen black flexible film, comprising: a black flexible substrate, and a non-dense laminated structure coating formed on the surface of the black flexible substrate and formed by cross-linking at least one of hydrotalcite nanosheets or hydrotalcite-like nanosheets and a silane coupling agent; the black flexible substrate comprises a black polyimide film, a black polyester film, a black polyethylene film, etc.; preferably, the solar absorption ratio of the black flexible substrate is α s ≥0.88, hemispherical emissivity ε H≥0.78.

[0005] Specifically, the present invention creatively proposes a low-orbit space environment protection idea of ​​constructing a scale-like laminated bionic structure coating based on hydrotalcite or hydrotalcite-like layered nanomaterials. Specifically, a silane coupling agent is used to modify hydrotalcite or hydrotalcite-like nanosheets combined with a black flexible film surface activation treatment to construct a firm anti-proton oxygen film layer on the surface of the black flexible substrate film.

[0006] In the present invention, the metal oxide generated by the reaction of hydrotalcite or hydrotalcite-like nanosheets with atomic oxygen is inert to atomic oxygen, and the atomic oxygen inert substance will not react with atomic oxygen to generate volatile substances. The arrangement of the nanosheets parallel to the substrate direction is equivalent to infinitely extending the erosion path of atomic oxygen to the substrate, which can effectively isolate atomic oxygen and prevent it from invading the substrate, thereby improving the substrate's anti-proton oxygen erosion performance. The coating not only has relatively excellent anti-proton oxygen performance, but also has the advantages of good flexibility and resistance to peeling and cracking; and the non-dense scale-like laminated bionic micro-nano structure of the surface modification layer is used to reduce the refractive index and reflectivity, thereby further improving the solar absorption ratio.

[0007] Preferably, the black polyimide film comprises: a polyimide film containing an inorganic black filler and / or an organic black filler, or a polyimide film coated with an inorganic black filler and / or an organic black filler; the inorganic black filler comprises at least one of black metal oxide, carbon black and graphite; the organic black filler comprises at least one of perylene black and aniline black; Preferably, the black polyimide film is a polyimide film doped with carbon black, the content of carbon black is 0.2-20wt%, and the total content of carbon element in the black polyimide is 65-85wt%; Preferably, the thickness of the black polyimide matrix is ​​3 to 100 μm. Among them, the black flexible matrix is ​​preferably a black polyimide matrix with excellent performance, which can be prepared by adding various light-shielding fillers to the polyimide precursor (polyamic acid) for blending, such as black metal oxides, carbon black, graphite, perylene black, aniline black and other inorganic or organic black fillers, and then forming a film through cast drying and high-temperature imidization treatment; or these light-shielding substances are made into a slurry and coated on a polyimide film. The black polyimide is preferably a heat-resistant inorganic black filler modified polyimide, such as a carbon-containing polyimide doped with carbon black.

[0008] Preferably, the black polyimide matrix has carboxyl groups, hydroxyl groups or amine groups on its surface; the black polyimide matrix is ​​subjected to surface activation treatment to obtain a black polyimide matrix having carboxyl groups, hydroxyl groups or amine groups on its surface.

[0009] Preferably, the chemical composition of the hydrotalcite nanosheets or hydrotalcite-like nanosheets is [M 2+ 1-x M3+ x (OH)2] x+ A n- x / n mH2O, where M 2+ is a divalent metal cation, preferably selected from Mg 2+ 、Ni 2+ 、Co 2+ 、Zn 2+ , Cu 2+ At least one of 3+ is a trivalent metal cation, preferably selected from Al 3+ Cr 3+ , Fe 3+ Sc 3+ At least one of n- is an anion, preferably selected from CO3 2- 、NO3 - , Cl - OH - 、SO4 2- PO4 3- 、C6H4(COO)2 2- At least one of the following; x is in the range of 0.1 to 0.5, preferably 0.2 to 0.33; more preferably, the divalent metal cation is Mg 2+ , the trivalent metal cation is Al 3+ , most preferably Mg 2+ :Al 3+ =2:1.

[0010] Preferably, the hydrotalcite nanosheet or hydrotalcite-like nanosheet has a nearly regular hexagon or a circle; the diameter of the circumscribed circle of the circle or nearly hexagon is between 50 and 1000 nm, and the thickness of the hydrotalcite nanosheet is between 1 and 50 nm.

[0011] Preferably, the present invention can achieve band gap narrowing by introducing transition metals to synthesize hydrotalcite with ternary metal components, and further preparing sulfur-doped ternary hydrotalcite coatings by sulfurization. The narrowing of the band gap can effectively achieve conductivity and further have an antistatic function.

[0012] In the present invention, the surface micro-nano structure of the non-dense film layer resisting proton oxygen can be further adjusted by controlling the size of the hydrotalcite or hydrotalcite-like nanosheets, and the arrangement structure and refractive index of the film layer can be adjusted by controlling the size of the hydrotalcite or hydrotalcite-like nanosheets and the amount of silane coupling agent added, thereby realizing a gradual change from the low refractive index of the film layer to the high refractive index of the matrix, reducing the surface reflectivity, and realizing a high solar absorption ratio. The raw materials and preparation are inexpensive and easy to implement.

[0013] Preferably, the silane coupling agent is selected from at least one of aminohydrocarbon silane, 3-mercaptopropyltrimethoxysilane, γ-(2,3-epoxypropyloxy)propyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane; the aminohydrocarbon silane is selected from at least one of N-aminoethyl-3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane and 3-aminopropyltriethoxysilane, preferably 3-aminopropyltriethoxysilane; The silane coupling agent simultaneously undergoes bonding reactions with the flexible substrate and the hydrotalcite or hydrotalcite-like nanosheets.

[0014] Preferably, the antigenic oxygen hydrotalcite coating further comprises a silane coupling agent modified layer distributed between the polymer matrix and the non-dense scale-like laminated bionic micro-nano structure layer; the thickness of the silane coupling agent modified layer is 10 nm to 10 μm.

[0015] Preferably, the ratio of at least one of the hydrotalcite nanosheets or hydrotalcite-like nanosheets to the silane coupling agent in the non-dense scale-like laminated bionic micro-nanostructure layer is (5-40) mg: (5-30) μL.

[0016] Preferably, the interlayer spacing of the hydrotalcite or hydrotalcite-like nanosheets is as large as possible, and the scale-like laminated bionic micro-nanostructure layer should be as loose as possible to minimize reflection while meeting the coating firmness and anti-proton oxygen performance; the total thickness of the scale-like laminated bionic micro-nanostructure layer is 50nm to 10μm.

[0017] On the other hand, the present invention provides a method for preparing an anti-oxygen black flexible film, comprising: adding a silane coupling agent to an aqueous dispersion containing at least one of hydrotalcite nanosheets or hydrotalcite-like nanosheets and mixing, then coating the mixture on the surface of a black flexible substrate, and heat treating the mixture at 80 to 300° C. for 1 to 72 hours to obtain an anti-oxygen black flexible film.

[0018] Preferably, the black flexible film is preferably a black polyimide substrate. Before coating, the black polyimide substrate is subjected to a surface activation treatment; preferably, the surface activation treatment includes: wet chemical treatment, ultraviolet radiation treatment, plasma treatment, and corona treatment; more preferably, the wet chemical treatment is acid-base modification, and the alkali-acid modification includes alkali treatment and acid treatment; most preferably, the polyimide substrate is treated in a NaOH solution with a concentration of 0.1 to 6 mol / L and an acetic acid solution with a concentration of 0.1 to 6 mol / L for 0.2 to 6 h, respectively, and then washed and dried to obtain a polymer matrix with surface active groups (hydroxyl, carboxyl or amine).

[0019] Preferably, the concentration of the aqueous dispersion containing at least one of the hydrotalcite nanosheets or the hydrotalcite-like nanosheets is 5 to 100 mg / mL; and the mixing method is stirring or ultrasonic dispersion.

[0020] Preferably, the coating is performed at least once; the coating includes spin coating, drip coating, spray coating, scraping, coating or static pulling.

[0021] Preferably, after the coated hydrotalcite nanosheets or hydrotalcite-like nanosheets are heat-treated, they are then subjected to a stabilization treatment; the stabilization treatment includes: one of ultraviolet oxidation treatment, plasma treatment or ozone oxidation treatment and a subsequent secondary heat treatment process to reduce stress; The UV light intensity of the ultraviolet light oxidation treatment is 2 to 15 mW / cm 2 , time is 1 to 24 hours; The parameters of the oxygen plasma treatment include: controlling the oxygen flow rate to 100 to 500 sccm and the treatment time to 20 to 480 s; The parameters of the ozone oxidation treatment include: controlling the ozone concentration to 40-80 PPM and the treatment time to 10-120 min; The temperature of the secondary heat treatment is 80-300° C., and the time is 2-48 hours.

[0022] On the other hand, the present invention also provides the application of the anti-proton oxygen black flexible film in the aerospace field. Utilizing its high absorption ratio characteristics, the flexible film is very suitable for the optical systems of various spacecraft, strongly absorbs light in a certain wavelength range, reduces the stray light and astigmatism of the system, such as the back of the satellite antenna and the camera tube, eliminates or avoids the interference of various stray lights on the imaging system and sensor. In addition, the high solar absorption ratio and high emissivity characteristics of the flexible film can be widely used in the thermal control system of spacecraft, achieving high absorption of light in the solar radiation band and high emission of light in the infrared band. Preferably, its anti-proton oxygen function can protect the matrix black polyimide film itself from damage by atomic oxygen in the low-orbit space environment, and meet the life design requirements of low-orbit spacecraft service.

[0023] Beneficial effects of the present invention: (1) The present invention provides an anti-oxygen black flexible film, which uses hydrotalcite or hydrotalcite-like layered nanomaterials to simultaneously achieve excellent anti-oxygen function and the function of reducing reflection and increasing solar absorption ratio in a non-dense structure in a single film layer; (2) The present invention provides an anti-atomic oxygen black flexible film, which has excellent resistance to space environment radiation. Its base material is a black flexible film material, and the outermost main skeleton exposed to the space environment is a layered inorganic nanomaterial of hydrotalcite or hydrotalcite-like coating. The coating itself has excellent resistance to atomic oxygen. The hydrotalcite or hydrotalcite-like coating can form a scaly laminated structure parallel to the direction of the substrate, and form a stable composite metal oxide after reacting with atomic oxygen. The process of converting to metal oxide still tends to maintain a stable structure. The scaly laminated structure with a "maze effect" can fully utilize the spontaneous adsorption of highly active atomic oxygen after entering the protective layer in the direction of atomic oxygen erosion to capture and stably convert atomic oxygen, which is equivalent to infinitely extending the erosion path of atomic oxygen to the substrate, thereby effectively preventing the erosion of the substrate by atomic oxygen. In addition, the inorganic hydrotalcite coating and the black polyimide base material exposed to the space environment have good tolerance to ultraviolet rays, electrons, and protons, so that the anti-atomic oxygen black polyimide film of the present invention has the beneficial effect of resistance to space environment radiation; (3) The present invention provides an anti-proton oxygen black flexible film, which further improves the solar absorption ratio on the basis of making full use of the light absorption characteristics of conventional black polyimide films. Different from the current idea of ​​achieving high solar absorption ratios using carbon nanotubes or black paint materials, the anti-proton oxygen black polyimide film of the present invention combines the matrix characteristics and surface modification technology, and while achieving high space environment stability, it also makes full use of optical interference to further improve the high solar absorption ratio. On the one hand, it fully utilizes the characteristics of the black polyimide matrix that already contains light-absorbing materials such as carbon black to achieve the absorption of sunlight; on the other hand, in addition to the micro-nano structure formed by the stacking, the scale stacking structure on the surface of the black polyimide matrix, the hydrotalcite or hydrotalcite-like nanosheets themselves are layered structures, with a certain distance between layers, and a refractive index (usually about 1.5) lower than that of black polyimide (usually about 1.7). The gradual change of the refractive index from vacuum or atmospheric environment to black polyimide takes into account both the high absorption of sunlight by carbon materials and the anti-reflection effect of surface hydrotalcite. Unlike conventional carbon materials and other solar absorption ratio materials, it is difficult to simultaneously utilize the above-mentioned high solar absorption ratio regulation mechanism, and while achieving high solar absorption ratio characteristics, it is easy to lose the stability of the space environment or excessively pursue high solar absorption ratios and adopt too loose structures to lose the firmness of the film layer, affecting subsequent use and processing. The present invention increases the solar absorption ratio of commercial polyimide film from about 0.92 to above 0.96 while achieving high space environment stability; (4) Anti-oxidative black flexible thin film has strong inter-layer bonding, and excellent film adhesion is mainly achieved through chemical bonding. The hydrotalcite or hydrotalcite-like coating is formed by in-situ construction of a silane coupling agent on the surface of a black polyimide substrate after surface activation. The silane coupling agent that can react with active groups such as hydroxyl groups on the surface of the black flexible substrate after surface activation forms a strong chemical bond with the hydrotalcite coating and the black flexible substrate. In addition, a small amount of small molecular silane coupling agent diffuses into the black flexible substrate after surface activation to form a thinner chemically bonded diffusion reaction film layer to achieve a strong bond. In terms of flexibility, unlike the existing dense inorganic coatings that are easy to peel off and crack, this coating material has a highly oriented nanosheet stacking structure, which releases stress through slip between scales and slip of atomic layers within scales, and is not easy to crack or fall off during the bending process. However, it is dense in the direction of atomic oxygen erosion, and can fully capture and transform atomic oxygen to make it lose its corrosiveness, thus achieving the coordinated optimization of the film refractive index and the mechanical properties of the coating. The film has excellent protective performance and is strong and durable. (5) The hydrotalcite or hydrotalcite-like coating structure used in the present invention is composed of positive charges between the main layers and anions in the interlayer guest. Therefore, the chemical composition of the layers, the internal space composition of the layers, the internal grain size and distribution, and the type and number of anions between the layers are all controllable, which is very suitable for the multifunctional design of micro-nano structure control and composition. For example, its inorganic layers can scatter and absorb a small amount of ultraviolet rays, and the exchangeability of the interlayer guest allows organic anions with ultraviolet absorption properties to enter the interlayer of the hydrotalcite or hydrotalcite-like layers to achieve ultraviolet shielding. In addition, by introducing transition metals to synthesize hydrotalcite with ternary metal components, and further through sulfurization, the microstructure band gap is narrowed in two steps, and the narrowing of the band gap can effectively achieve the improvement of conductivity and ultraviolet protection, which is beneficial for its use in higher orbits; (6) The anti-anti-oxygen black flexible film of the present invention has the advantage of being easy to cut and process like conventional flexible film materials, and can be used in combination with other flexible thermal control materials. Moreover, the film itself is easy to paste and construct, and is convenient for on-site pasting and implementation on the surface of a spacecraft, and can meet the requirements of multi-scenario use of a spacecraft. (7) The raw materials of the anti-oxygen high solar absorption ratio flexible film of the present invention are commonly used commercial materials, which can be purchased in bulk at a relatively low price. At the same time, it has low requirements for equipment, does not have the requirements of conventional coating solutions for vacuum control, has a simple process, is easy to operate, and has no process factors that limit its large-scale implementation, which is conducive to low-cost, batch development and easy to further promote and apply in the civilian field. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1The schematic diagram of the structure of the anti-proton oxygen black flexible film disclosed in the present invention is a coating of a scale-laminated bionic structure constructed by coating a silane coupling agent-modified hydrotalcite or hydrotalcite-like nanosheets on the surface of a black polyimide substrate. The outermost surface coating is composed of a laminated skeleton composed of hydrotalcite or hydrotalcite-like nanosheets, and there is a non-dense micro-nano structure between the laminated skeletons; Figure 2 This is an electron microscope photograph of the surface of the anti-oxygen black flexible film in Example 1. It can be seen from the figure that the microstructure of the coating is formed by hydrotalcite or hydrotalcite-like nanosheets arranged in a scale-like stacking manner, which is a non-dense film layer; Figure 3 This is the EDS image of the surface of the anti-atomic oxygen black flexible film in Example 1. It can be seen from the figure that the coating contains elements such as magnesium, aluminum, silicon, carbon, nitrogen, and oxygen. Since the depth of the EDS test signal is greater than the thickness of the coating, the test signal will contain matrix element information, but magnesium, aluminum, and silicon elements are not matrix components, indicating that a coating containing silane coupling agent-modified hydrotalcite nanosheets has been successfully prepared, in which magnesium, aluminum, and silicon elements can play a role in atomic oxygen protection. DETAILED DESCRIPTION

[0025] The present invention is further described below by the following embodiments. It should be understood that the following embodiments are only used to illustrate the present invention, but not to limit the present invention.

[0026] In the present disclosure, the anti-proton black flexible film comprises: a black flexible substrate, and a scale-like laminated structure coating formed on the surface of the black flexible substrate and composed of a laminated structure formed by hydrotalcite nanosheets or hydrotalcite-like nanosheets with a certain sheet size and a small amount of silane coupling agent. In an optional embodiment, the chemical composition of the hydrotalcite nanosheets or hydrotalcite-like nanosheets of a certain size can be expressed as [M 2+ 1-x M 3+ x (OH)2] x+ A n- x / n ·mH2O. 2+ For divalent metal cations, such as Mg 2+ 、Ni 2+ 、Co 2+ 、Zn 2+ , Cu 2+ etc.; M 3+ For trivalent metal cations, such as Al 3+ Cr 3+ , Fe 3+ Sc 3+ etc. n- Anions, such as CO3 2- 、NO3 - , Cl- OH - 、SO4 2- PO4 3- 、C6H4(COO)2 2- Inorganic and organic ions and complex ions; x ranges from 0.1 to 0.5, preferably from 0.2 to 0.33. The preferred composition is a hydrotalcite-like nanosheet with a magnesium-aluminum ratio of 2:1, wherein the divalent metal cation, trivalent metal cation, and anion are Mg 2+ 、Al 3+ , Cl - , and Mg 2+ :Al 3+ =2:1.

[0027] In an optional embodiment, the hydrotalcite or hydrotalcite-like nanosheets of a certain size can be prepared in large quantities by a two-step method of co-precipitation and hydrothermal treatment, and the sheet layers are nearly regular hexagons or circles, the circle diameter or the hexagonal circumscribed circle diameter is in the range of 50nm to 1000nm, and the thickness of the hydrotalcite or hydrotalcite-like nanosheets is 1 to 50nm.

[0028] In an optional embodiment, the obtained anti-proton black flexible thin film can be stabilized to further form a stable silicon oxide film layer on the outermost surface, reduce the organic components in the silane coupling agent used in the porous micro-nano structure coating, reduce the volatilization of organic components during on-orbit service, and reduce possible pollution to the optical system. For conventional applications, the organic component content is already very low, meeting the requirements of the thermal control coating for vacuum volatilization performance, and no stabilization treatment is required.

[0029] The following is an exemplary description of the method for preparing the anti-ion oxygen black flexible film in the present invention.

[0030] Preparation of black polyimide substrate surface activation layer. After the black polyimide substrate is cleaned, it is subjected to surface activation treatment by wet chemical treatment, ultraviolet irradiation treatment or plasma treatment to prepare an activation layer having carboxyl, hydroxyl or amine groups on the surface. Preferably, the surface activation treatment is a wet chemical treatment; more preferably, the surface of the polymer substrate is subjected to alkali-acid modification; the alkali-acid modification includes alkali treatment and acid treatment, and then washed and dried to obtain a black polyimide substrate with surface active groups (hydroxyl, carboxyl, amine). Among them, the thickness of the black polyimide substrate is not less than 3μm, and it is a type of modified black polyimide substrate in which carboxyl, hydroxyl and amine groups are generated on the surface of the black polyimide after surface activation treatment, including but not limited to: black polyimide modified by inorganic or organic black fillers such as black metal oxides, carbon black, graphite, perylene black, aniline black, such as carbon black modified black polyimide and black polyimide substrate film using polyacrylonitrile as a light shielding agent. The content of carbon black is generally 0.2-20wt%.

[0031] Preparation of an aqueous dispersion containing hydrotalcite nanosheets or / and hydrotalcite-like nanosheets. Preferably, the dispersion is prepared by a two-step method of coprecipitation and hydrothermal method. Taking the preferred magnesium-aluminum hydrotalcite-like nanosheets as an example, the steps of preparing the hydrotalcite-like nanosheets by the two-step method of coprecipitation and hydrothermal method include: preparing a solution of magnesium chloride hexahydrate, aluminum chloride hexahydrate, and water in a molar ratio of (3-x): 3x: 350 (where x ranges from 0.1 to 0.5, preferably 0.2 to 0.33), adding ammonia water and stirring to adjust the pH to 9 to 10, and standing after stirring. The resulting suspension is centrifuged and washed with deionized water to a pH of 8 to 9. It is then placed in an oven at 80 to 200°C for hydrothermal treatment for 24 hours.

[0032] A certain amount of aminoalkylsilane is added as a crosslinking agent to the aqueous dispersion containing hydrotalcite nanosheets or / and hydrotalcite-like nanosheets, and then after stirring for a certain period of time, it is coated on the polymer substrate modified by alkali / acid two steps to form a wet film. The coating method is any one of spin coating, drop coating, spray coating, blade coating, static pull-up or coating.

[0033] In an optional embodiment, the heat treatment temperature may be a temperature value within 80 to 300° C. or a gradient change formed by several temperature values. The total time of the heat treatment may be 1 to 48 hours. Preferably, the heat treatment process is 80° C., 110° C., 150° C. for 1 hour, 1 hour, and 3 hours, respectively.

[0034] Stabilization treatment. The stabilization treatment is ultraviolet oxidation treatment, plasma treatment, or ozone oxidation treatment. Preferably, the ultraviolet oxidation treatment is first performed, and then heat treatment is performed to reduce stress. The UV light intensity of the ultraviolet oxidation treatment is 2 to 15 mW / cm 2 The heat treatment temperature is 100-150°C and the time is 2-48 hours. The outermost SiOx-like surface rich in Si and O can be further formed on the outer surface of the atomic oxygen protective layer by stabilization treatment.

[0035] Performance Test: The surface morphology and composition of the samples were tested using a scanning electron microscope combined with an energy dispersive X-ray spectrometer. Refer to GJB 2502.2 Test Method for Thermal Control Coatings of Spacecraft Part 2: Solar Absorption Ratio Test to test the solar absorption ratio of the coating surface; refer to GJB 2502.3 Test Method for Thermal Control Coatings of Spacecraft Part 3: Emissivity Test to test the hemispherical emissivity of the coating surface; refer to GJB 2704 General Specification for Thermal Control Coatings of Spacecraft to use 3M610 tape (nominal tension 4.7N / cm) to test the adhesion; refer to GB / T 6742 Paint and Varnish Bend Test (Cylindrical Mandrel) to test the surface cracking of the surface modified surface after the bending test (180°) of a cylindrical bending tester with a bending diameter of 2mm; refer to GJB 2502.8 Test Method for Thermal Control Coatings of Spacecraft Part 8: Thermal Cycle Test to carry out hot and cold alternating tests, and test the appearance and thermal radiation performance after 100 high and low temperature alternations at -110℃~+150℃; refer to GJB 2502.5 Test method for thermal control coatings of spacecraft Part 5: Vacuum-ultraviolet irradiation test Carry out ultraviolet irradiation test to check the thermal radiation performance after vacuum-ultraviolet irradiation test with cumulative dose of 2000ESH; refer to GJB 2502.7 Test method for thermal control coatings of spacecraft Part 7: Vacuum-electron irradiation test with cumulative dose of 2.5×10 15 e / cm 2 Thermal radiation performance after electron irradiation test; refer to GJB 2502.6 Spacecraft Thermal Control Coating Test Method Part 6: Vacuum-Proton Irradiation Test Inspection Cumulative Dose 2.5×10 15 p / cm 2 Thermal radiation performance after proton irradiation test; Atomic oxygen irradiation test was carried out according to GJB 2502.9 Test Method for Thermal Control Coatings of Spacecraft Part 9: Atomic Oxygen Test, and the cumulative dose was 2.61×10 21 atoms / cm 2 The mass loss and thermal radiation performance after the atomic oxygen irradiation test; referring to GJB 2704 General Specification for Spacecraft Thermal Control Coatings, use an ultra-fine dust-free cloth dipped in acetone to gently wipe the surface along the surface direction of the modified layer, wipe it 3 times and observe the appearance with the naked eye to test its cleaning resistance.

[0036] The following further examples are given to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific values ​​​​exemplified below.

[0037] Example 1 According to the technical solution of the present invention, an anti-oxidation black polyimide flexible film material is prepared. (1) Preparation of the black polyimide substrate surface activation layer. The HB-N-25 black polyimide film product produced by Shenzhen Ruihuatai Film Technology Co., Ltd. was used, which had a solar absorption ratio of 0.92 and a hemispherical emissivity of 0.88. The polyimide flexible substrate was scrubbed with a dust-free cloth dipped in a mixture of ethanol and acetone to remove dust, oil stains and other contamination during the preparation and transportation process; the PI film was placed in a 1 mol / L sodium hydroxide alkaline solution for 1 hour, and then the residual alkaline solution was rinsed with deionized water and ethanol. The rinsed PI film was then placed in a 1 mol / L acetic acid acid solution for 1 hour, and then rinsed clean. Finally, the wet film was dried at room temperature to obtain an alkali-acid modified PI substrate; (2) Preparation of aqueous dispersion of magnesium-aluminum hydrotalcite nanosheets. Dissolve 0.6449 g of magnesium chloride hexahydrate and 1.9314 g of aluminum chloride hexahydrate in 50 mL of deionized water to prepare a precursor solution. Quickly add ammonia water and stir to adjust the pH to 9-10. After stirring, let it stand for aging. The resulting white suspension was centrifuged and washed with deionized water several times to a precipitate with a pH of 8-9. After washing, add a certain amount of deionized water to the precipitate and stir evenly to obtain a dispersion with a mass concentration of 18 mg / mL. The dispersion was then hydroheated in an oven at 150°C for 24 hours. Finally, a magnesium-aluminum hydrotalcite nanosheet dispersion with a nearly regular hexagonal shape and a circumscribed circle diameter of approximately 320 nm and a thickness of approximately 7.3 nm was obtained; (3) Preparation of hydrotalcite-like flaky laminated structure on the surface of black polyimide matrix. Add 3-aminopropyltriethoxysilane (50 μL) (wherein the ratio of hydrotalcite nanosheets to silane coupling agent is 9 mg:5 μL) to the above-mentioned magnesium-aluminum hydrotalcite nanosheet dispersion (5 mL). After stirring, coat it on the surface of the surface-modified black polyimide film, and then place it in an air atmosphere at 60, 90, 120°C, and 150°C for heat treatment for 1h, 1h, 3h, and 3h, respectively, to obtain the above-mentioned fish-scale-like, non-dense structured anti-proton oxygen hydrotalcite coating with a thickness of about 1 μm; (4) Stabilization treatment. The material prepared in step (3) is subjected to ultraviolet light oxidation treatment and heat treatment; the UV light intensity of the ultraviolet light oxidation treatment is 5mW / cm 2 , time is 1 hour; heat treatment temperature is 60, 90, 120, 150 ℃ in air atmosphere for 1h, 1h, 3h, 3h, respectively, to form Si and O-rich SiO x Outermost surface.

[0038] Systematic material performance and environmental adaptability tests were carried out on the anti-oxygen black polyimide flexible film material prepared according to the above steps. The results show that the treated surface has a dark black appearance, no obvious foreign matter or stains on the surface, the film layer has a uniform color, no peeling or shedding, and the appearance is intact; under a scanning electron microscope, the surface presents a scale-like laminated structure, and the Mg, Al, and Si contents are 11.81at%, 5.70at%, and 4.50at%, respectively. Compared with the sample obtained in step (3), the Mg (10.61at%), Al (5.16at%), and Si (3.98at%) contents are slightly increased, which is beneficial to reduce the volatilization of organic components during the action of atomic oxygen on orbit, but the stabilization influence depth is shallow, the EDS test depth is deep, and the test results do not change much; the solar absorption ratio α s is 0.96~0.97, about 0.96, hemispherical emissivity ε H The thermal radiation performance of the high solar absorption ratio and high hemispherical emissivity is less affected by the stabilization treatment. After the 3M610 tape pull-off test, the film layer has no blistering and no obvious shedding, and the film layer has good adhesion. After the bending test (180°, 1000 times) of a cylindrical bending tester with a bending diameter of 2 mm, the film layer has no obvious shedding, and the peeling and cracking resistance is excellent. -110℃~+150℃, 100 cycles, the residence time at the high temperature and low temperature end is 5 minutes, and the transfer time is less than 10s. After the test, the appearance is intact, without blistering, peeling, or shedding. There is no obvious change in the solar absorption ratio and hemispherical emissivity before and after the test, and the cold and hot alternating performance is excellent. In a vacuum degree better than 1.3×10 -3 Pa vacuum condition, after the vacuum-ultraviolet irradiation test with a cumulative dose of 2000ESH (equivalent solar hours), the solar absorption ratio and hemispherical emissivity have no obvious changes, and have excellent ultraviolet radiation resistance; after the total electron irradiation agent of 2.5×10 15 e / cm 2 After the energy irradiation test, the solar absorption ratio and hemispherical emissivity have no obvious changes, and have excellent resistance to electron irradiation; in a vacuum degree better than 1.3×10 -3 Pa vacuum condition, the total proton irradiation dose was 2.5×10 14 p / cm 2 After the energy irradiation test, the solar absorption ratio and hemispherical emissivity did not change significantly, and the sample had good proton irradiation resistance. 21 atoms / cm 2 After atomic oxygen irradiation, the mass loss per unit area is -0.01 mg / cm 2The substrate is intact without any signs of corrosion, the mass change is within the error range of weighing, and the solar absorption ratio and hemispherical emissivity have no obvious changes, indicating that the black polyimide flexible film with a hydrotalcite-like flaky laminated structure coating on the surface has excellent anti-oxygen properties. In addition, the sample also has a certain degree of cleaning resistance. After being lightly wiped three times with an ultra-fine dust-free cloth dipped in acetone (chemically pure), there is no obvious foreign matter or pollution on the surface, and the surface modification layer has a dark black appearance. The surface modification layer is uniform, without peeling or falling off. Combined with the adhesion and bending tests, it can be seen that the film layer has excellent firmness and durability.

[0039] Example 2 The preparation process of the hydrotalcite-like flaky laminated structure coating in Example 2 refers to Example 1, with the only difference being that the hydrothermal temperature of the dispersion is 80°C. When the dispersion in Example 2 is hydrothermaled in an oven at 80°C for 24 hours, the prepared magnesium-aluminum hydrotalcite nanosheets are still nearly regular hexagons, and the diameter of the circumscribed circle is about 120nm. The results show that the treated surface has a dark black appearance, no obvious foreign matter or stains on the surface, the film layer has uniform color, no peeling or shedding, and the appearance is intact; the solar absorption ratio α s is 0.96~0.97, about 0.96, hemispherical emissivity ε H The black polyimide flexible film has a thermal radiation performance of high solar absorption ratio and high hemispherical emissivity. 21 atoms / cm 2 After atomic oxygen irradiation, the mass loss per unit area is 0.01 mg / cm 2 The substrate is intact without any signs of corrosion, the mass change is within the error range of weighing, and the solar absorption ratio and hemispherical emissivity have no obvious changes, indicating that the scale-like laminated structure coating constructed by hydrotalcite nanosheets of a certain size on the surface of the black flexible polyimide substrate has excellent anti-proton oxygen performance.

[0040] Example 3 The preparation process of the hydrotalcite-type flaky laminated structure coating in this Example 3 refers to that in Example 1, the only difference is the amount of silane coupling agent added. In this Example 3, 3-aminopropyltriethoxysilane (25 μL) was added to the above-mentioned magnesium-aluminum hydrotalcite nanosheet dispersion (5 mL) (wherein the ratio of hydrotalcite nanosheets to silane coupling agent is 18 mg: 5 μL). The results show that the treated surface has a dark black appearance, with no obvious foreign matter or stains on the surface, the film layer has uniform color, no peeling or shedding, and the appearance is intact; the solar absorption ratio α s is 0.96~0.97, about 0.96, hemispherical emissivity ε H The black polyimide flexible film has a thermal radiation performance of high solar absorption ratio and high hemispherical emissivity.21 atoms / cm 2 After atomic oxygen irradiation, there is no obvious mass loss, the substrate is intact without any signs of corrosion, and the solar absorption ratio and hemispherical emissivity have no obvious changes, indicating that the scale-like laminated structure coating constructed by hydrotalcite nanosheets of a certain size on the surface of the black flexible polyimide matrix has excellent anti-atomic oxygen performance.

[0041] Example 4 The preparation process of the hydrotalcite-like flaky laminated structure coating in this Example 3 refers to that in Example 1, the only difference is the amount of silane coupling agent added. In this Example 3, N-aminoethyl-3-aminopropyltriethoxysilane (50 μL) was added to the above-mentioned magnesium-aluminum hydrotalcite nanosheet dispersion (5 mL) (wherein the ratio of hydrotalcite nanosheets to silane coupling agent is 9 mg: 5 μL). The results show that the treated surface has a dark black appearance, with no obvious foreign matter or stains on the surface, the film layer has uniform color, no peeling or shedding, and the appearance is intact; the solar absorption ratio α s is 0.96~0.97, about 0.96, hemispherical emissivity ε H The black polyimide flexible film has a thermal radiation performance of high solar absorption ratio and high hemispherical emissivity. 21 atoms / cm 2 After atomic oxygen irradiation, there is no obvious mass loss, the substrate is intact without any signs of corrosion, and the solar absorption ratio and hemispherical emissivity have no obvious changes, indicating that the scale-like laminated structure coating constructed by hydrotalcite nanosheets of a certain size on the surface of the black flexible polyimide matrix has excellent anti-atomic oxygen performance.

[0042] Comparative Example 1 If the conventional commercial black polyimide film (HB-N-25 product of Shenzhen Ruihuatai Film Technology Co., Ltd.) used in the present invention is not surface treated, its solar absorption ratio is α s is 0.92, and the hemispherical emissivity ε H is 0.88, after 2.61×10 21 atoms / cm 2 After atomic oxygen irradiation, the etched polyimide material has been completely etched away. The erosion rate of polyimide materials does not change much with the increase of atomic oxygen dose. The mass loss increases linearly with the increase of atomic oxygen dose. 20 atoms / cm 2 ) Mass loss under atomic oxygen test is 0.40 mg / cm 2 Calculation, 2.61×10 21 atoms / cm 2 The theoretical mass loss after atomic oxygen irradiation is about 9.49 mg / cm 2The etched thickness is 66.84μm, far exceeding the actual film thickness of 25μm. This comparison also shows that if conventional commercial black polyimide film is used in the low-orbit atomic oxygen environment, the influence of atomic oxygen must be considered, and due to the high erosion rate of atomic oxygen, it is difficult to achieve long-term service in the lower orbit by using multiple layers of conventional commercial black polyimide film.

[0043] Comparative Example 2 Widely used conventional polyimide films (such as the commonly used PMDA-ODA polyimide films without carbon black) are yellow transparent flexible films. Most visible light will pass through the polyimide film, and its solar absorption is relatively low. The solar absorption ratio of a 25μm thick film is less than 0.40 (tested by subtracting transmission and reflection). For example, the solar absorption ratio of Kapton 100HN type (about 25μm thick) yellow polyimide film tested is about 0.24, and the hemispherical emissivity is about 0.48; after increasing the film thickness to 50μm, the solar absorption ratio of Kapton 200HN type film is only 0.30, and the hemispherical emissivity is about 0.60; Ruihuatai's 50μm thick KHN type film has a solar absorption ratio of 0.24 and a hemispherical emissivity of about 0.61; although the emissivity of the polymer film can be improved by increasing its thickness, the widely used conventional yellow polyimide film has a relatively low solar absorption, which is far from meeting the requirements of high solar absorption ratio, and the emissivity is also lower than that of black polyimide film.

[0044] Comparative Example 3 See Example 1, the difference is: a conventional 25μm thick Kapton 100HN polyimide film is selected. Its absorptivity and emissivity are tested. The solar absorptivity of the sample using Kapton 100HN polyimide film is about 0.25, and the hemispherical emissivity is about 0.52; the results show that the solar absorptivity of the conventional yellow polyimide film is extremely limited by the method of the present invention. At the same time, although the emissivity of the conventional yellow polyimide film can be increased by the method of the present invention, it is still lower than that of the black polyimide film. The realization of high solar absorptivity and high emissivity must be achieved in combination with the selection of the substrate.

[0045] The raw materials listed in the present invention, as well as the upper and lower limits and interval values ​​of the raw materials of the present invention, and the upper and lower limits and interval values ​​of the process parameters can all realize the present invention, and the embodiments are not listed one by one here.

[0046] Finally, it is necessary to explain here that the above embodiments are only used to further illustrate the technical solution of the present invention in detail and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above content of the present invention all fall within the scope of protection of the present invention.

Claims

1. An anti-oxygen black flexible film, characterized in that: include: A black flexible substrate, and a non-dense laminated structure coating formed on the surface of the black flexible substrate and formed by cross-linking at least one of hydrotalcite nanosheets or hydrotalcite-like nanosheets and a silane coupling agent; The black flexible substrate includes a black polyimide film, a black polyester film, a black polyethylene film, etc. Preferably, the solar absorption ratio of the black flexible substrate is α s ≥0.88, hemispherical emissivity ε H ≥0.

78.

2. The anti-ion oxygen black flexible film according to claim 1, characterized in that: The black polyimide film includes: a polyimide film containing an inorganic black filler and / or an organic black filler, or a polyimide film coated with an inorganic black filler and / or an organic black filler; the inorganic black filler includes at least one of black metal oxide, carbon black, and graphite; the organic black filler includes at least one of perylene black and aniline black; Preferably, the black polyimide film is a polyimide film doped with carbon black, the content of carbon black is 0.2-20wt%, and the total content of carbon element in the black polyimide is 65-85wt%; Preferably, the thickness of the black polyimide matrix is ​​3-100 μm.

3. The anti-ion oxygen black flexible film according to claim 1, characterized in that: The surface of the black polyimide matrix has carboxyl groups, hydroxyl groups or amine groups; the black polyimide matrix is ​​subjected to surface activation treatment to obtain a black polyimide matrix having carboxyl groups, hydroxyl groups or amine groups on the surface.

4. The anti-ion oxygen black flexible film according to claim 1, characterized in that: The chemical composition of the hydrotalcite nanosheet or hydrotalcite-like nanosheet is [M 2+ 1-x M 3+ x (OH)2] x+ A n- x / n mH2O, where M 2+ is a divalent metal cation, preferably selected from Mg 2+ 、Ni 2+ 、Co 2+ 、Zn 2+ , Cu 2+ At least one of 3+ is a trivalent metal cation, preferably selected from Al 3+ Cr 3+ , Fe 3+ Sc 3+ At least one of n- is an anion, preferably selected from CO3 2- 、NO3 - , Cl - OH - 、SO4 2- PO4 3- 、C6H4(COO)2 2- At least one of the following; x is in the range of 0.1 to 0.5, preferably 0.2 to 0.33; more preferably, the divalent metal cation is Mg 2+ , the trivalent metal cation is Al 3+ , most preferably Mg 2+ :Al 3+ =2:

1.

5. The anti-ion oxygen black flexible film according to claim 1, characterized in that: The sheet layer of the hydrotalcite nanosheet or hydrotalcite-like nanosheet is nearly regular hexagonal or circular; the diameter of the circumscribed circle of the circular or nearly hexagonal shape is between 50 and 1000 nm, and the thickness of the hydrotalcite nanosheet is 1 to 50 nm.

6. The anti-ion oxygen black flexible film according to claim 1, characterized in that: The silane coupling agent is selected from at least one of aminohydrocarbon silane, 3-mercaptopropyltrimethoxysilane, γ-(2,3-epoxypropyloxy)propyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane; the aminohydrocarbon silane is selected from at least one of N-aminoethyl-3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane and 3-aminopropyltriethoxysilane, preferably 3-aminopropyltriethoxysilane; The silane coupling agent simultaneously undergoes bonding reactions with the flexible substrate and the hydrotalcite or hydrotalcite-like nanosheets.

7. The anti-ion oxygen black flexible film according to claim 1, characterized in that: The anti-oxygen hydrotalcite coating further comprises a silane coupling agent modified layer distributed between the polymer matrix and the non-dense scale-like laminated bionic micro-nano structure layer; the thickness of the silane coupling agent modified layer is 10 nm to 10 μm.

8. The anti-ionic oxygen black flexible film according to any one of claims 1 to 7, characterized in that: The ratio of at least one of the hydrotalcite nanosheets or hydrotalcite-like nanosheets to the silane coupling agent in the non-dense scale-like laminated bionic micro-nano structure layer is (5-40) mg: (5-30) μL. The total thickness of the non-dense scale-like laminated bionic micro-nano structure layer is 50 nm to 10 μm.

9. A method for preparing an anti-oxygen black flexible film according to any one of claims 1 to 8, characterized in that: include: A silane coupling agent is added to a water dispersion containing at least one of hydrotalcite nanosheets or hydrotalcite-like nanosheets and mixed, then coated on the surface of a black flexible substrate and heat treated at 80-300° C. for 1-72 hours to obtain an antiprotonypic black flexible film.

10. The preparation method according to claim 9, characterized in that: When the black flexible substrate is a black polyimide film, the black polyimide substrate is subjected to a surface activation treatment before coating; preferably, the surface activation treatment includes: wet chemical treatment, ultraviolet radiation treatment, plasma treatment, and corona treatment; more preferably, the wet chemical treatment is acid-base modification, and the alkali-acid modification includes alkali treatment and acid treatment; most preferably, the polyimide substrate is treated in a NaOH solution with a concentration of 0.1 to 6 mol / L and an acetic acid solution with a concentration of 0.1 to 6 mol / L for 0.2 to 6 h, respectively, and then washed and dried to obtain a polymer matrix with surface active groups (hydroxyl, carboxyl or amine groups).

11. The preparation method according to claim 9, characterized in that: The concentration of the aqueous dispersion containing at least one of the hydrotalcite nanosheets or the hydrotalcite-like nanosheets is 5-100 mg / mL; the mixing method is stirring or ultrasonic dispersion.

12. The preparation method according to any one of claims 9 to 11, characterized in that: The coating is performed at least once; the coating includes spin coating, drip coating, spray coating, scraping coating, spreading or static pulling.

13. The preparation method according to any one of claims 9 to 11, characterized in that: After the coated hydrotalcite nanosheets or hydrotalcite-like nanosheets are heat-treated, they are then subjected to a stabilization treatment; the stabilization treatment includes: one of ultraviolet light oxidation treatment, plasma treatment or ozone oxidation treatment and a subsequent secondary heat treatment process to reduce stress; The UV light intensity of the ultraviolet light oxidation treatment is 2 to 15 mW / cm 2 , time is 1 to 24 hours; The parameters of the oxygen plasma treatment include: controlling the oxygen flow rate to 100 to 500 sccm and the treatment time to 20 to 480 s; The parameters of the ozone oxidation treatment include: controlling the ozone concentration to 40-80 PPM and the treatment time to 10-120 min; The temperature of the secondary heat treatment is 80 to 300° C., and the time is 2 to 48 hours.

14. Use of the anti-ionic oxygen black flexible film according to any one of claims 1 to 8 in the aerospace field.

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