Anti-atomic oxygen / high solar absorption ratio / high emission flexible film and preparation method and application thereof

Abstract

The invention relates to an anti-atomic oxygen / high solar absorptivity / high emission flexible film and a preparation method and application thereof. The flexible thin film comprises a black flexible substrate, and an organic-inorganic hybrid silicon modified layer or / and a porous micro-nano structure coating which are sequentially formed on the surface of the black flexible substrate, the black flexible substrate comprises a black polyimide film, a black polyester film or a black polyethylene film; 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 present invention relates to an anti-oxygen / high solar absorption ratio / high emission flexible film and a preparation method and application thereof, which is mainly used in a spacecraft thermal control system 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. Polyimide (PI) has outstanding comprehensive properties, and its excellent high and low temperature stability, high strength, good flexibility, light weight, radiation resistance, and low outgassing rate make it an irreplaceable polymer material in the aerospace field. The black composite film obtained by carbon doping of polyimide film can have good light-shielding, thermal conductivity, electrical conductivity, anti-static and other properties. It can be used as electronic materials, electromagnetic interference elimination materials, stray light absorbing materials, and thermal conductive materials. It is used in spacecraft thermal control systems and structural systems. It is a space material that has received widespread attention in recent years. However, during space flight, the thermal radiation performance of conventional black polyimide films will change due to the effects of ultraviolet radiation, charged particle radiation, atomic oxygen and other space environments, causing the thermal control system to deviate from the original set indicators. Under the action of a high cumulative dose of atomic oxygen, the black polyimide film will be completely etched away and lose its functional characteristics, threatening the reliability and service life of the spacecraft. In addition, the current solar absorption ratio of black polyimide films is usually around 0.92, which is still a certain distance away from the demand for high solar absorption ratios of thermal control systems. Summary of the invention

[0003] To this end, the present invention provides a flexible film with anti-oxygen / high solar absorption ratio / high emission, and a preparation method and application thereof.

[0004] In one aspect, the present invention provides a flexible film, comprising: a black flexible substrate, and an organic-inorganic hybrid silicon modified layer or / and a porous micro-nano structure coating sequentially formed on the surface of a black polyimide substrate; the black flexible substrate comprises a black polyimide film, a black polyester film or a black polyethylene film; preferably, the solar absorption ratio of the black flexible substrate is α s ≥0.88, hemispherical emissivity ε H ≥0.78.

[0005] Different from the general carbon nanotube and other carbon materials to increase the high solar absorption ratio, the present invention is based on the fact that the black polyimide film substrate itself contains elements such as high absorption carbon black and has its own absorption characteristics of αs≥0.90. The refractive index of organic silicon and silicon oxide materials is lower than that of polyimide, which can reduce the reflectivity of the surface of the black polyimide film and further increase the absorption of the black polyimide film. At the same time, organic silicon and silicon oxide materials have higher space environment stability than general solar absorption materials. Therefore, the present invention creatively adopts organic silicon and silicon oxide to modify the surface of a black flexible substrate (such as a black polyimide film), construct an organic-inorganic silicon modified layer on the surface of the black flexible substrate to increase the space environment performance such as anti-proto-oxygen, and introduce a micro-nano structure layer on the surface of the surface modification layer to further improve the solar absorption ratio. The coating not only has relatively excellent anti-proto-oxygen performance, but also has good flexibility and anti-peeling and cracking; the composition of the nano oxide balls of the coating is replaceable so that different functions can be achieved; the raw materials and preparation prices are low; and the operation is easy to implement. In this patent, the pore size of the atomic oxygen resistant micro-nano porous coating is adjusted by controlling the size of the powder particles, and the porosity of the coating is adjusted by controlling the size of the powder particles and the amount of cross-linking agent added, thereby achieving a gradual change from low refractive index to high refractive index, reducing the surface reflectivity, and achieving a high solar absorption ratio.

[0006] Preferably, it comprises: a black flexible substrate, and an organic-inorganic hybrid silicon modified layer and a porous micro-nano structure coating sequentially formed on the surface of the black polyimide substrate.

[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. The black flexible matrix is ​​preferably a black polyimide matrix, which can be prepared by adding various light-shielding fillers to the polyimide precursor (polyamic acid), 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. Preferably, the black polyimide is preferably a heat-resistant inorganic black filler-modified polyimide, such as a carbon-containing polyimide doped with carbon black; the content of carbon black in the carbon-containing polyimide is 0.2 to 20 wt%, and the total content of carbon in the black polyimide is 65 to 85 wt%; the solar absorption ratio of the black polyimide matrix is ​​α s ≥0.88, hemispherical emissivity ε H ≥0.78; preferably, the thickness of the black polyimide matrix is ​​3 to 100 μm.

[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 surface activation treatment includes: wet chemical treatment, ultraviolet radiation treatment, plasma treatment, corona treatment; preferably, the wet chemical treatment is acid-base modification, and the alkali-acid modification includes alkali treatment and acid treatment; more preferably, the polyimide matrix 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).

[0010] Preferably, the organic-inorganic hybrid silicon modified layer is a gradient structure layer formed by chemical bonding formed by reaction diffusion of small molecule organic silicon on the surface of the black polyimide matrix; the chemical formula of the small molecule organic silicon is (YR) n SiX 4-n , 1≤n≤3, wherein Y is a carbon functional group capable of reacting with a modified black polyimide matrix, preferably at least one of an unsaturated isocyanate, an amine and a cyano group; X is a silicon functional group capable of reacting and bonding with the porous micro-nanostructure coating, preferably at least one of an alkoxy group, a halide group, an acyloxy group and a silanol group.

[0011] Preferably, the porous micro-nanostructure coating is composed of nano-oxide particles and a silane coupling agent; The nano-oxide particles are spherical nano-particles or quasi-spherical nano-particles, with a single particle size of 7nm to 40nm or a mixture of particles with a particle size of 7nm to 40nm and particles with a particle size of 50nm, and the amount of particles with a particle size of 50nm added does not exceed 50%; The organic silicon coupling agent is selected from at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-aminoethyl-3-aminopropyltriethoxysilane, and 3-aminopropylmethyldiethoxysilane, preferably 3-aminopropyltriethoxysilane. For example, nanoparticles with a particle size range of 7nm to 40nm are freely combined, or small particle sizes (such as 7nm) and larger particle sizes (such as 50nm, the addition amount does not exceed 50%) are combined.

[0012] Preferably, the ratio of the nano-oxide particles to the silane coupling agent is (2-100) mg: (0-10) μL; preferably, the ratio of the nano-oxide particles to the silane coupling agent is 50 mg: (0-10) μL and the content of the silane coupling agent is not 0; More preferably, the ratio of the nano-oxide particles to the silane coupling agent is 50 mg: (1-10) μL.

[0013] In another aspect, the present invention provides a method for preparing a flexible film. When the black flexible substrate is a black polyimide film, the preparation method comprises: (1) Surface activation treatment of black polyimide substrate; (2) coating a small molecule silicone solution on the surface of a black polyimide substrate after surface activation treatment, and obtaining a surface-modified black polyimide film through heat treatment; (3) coating the nano-oxide solution on the surface of the surface-modified black polyimide film, and obtaining a micro-nano porous coating by heat treatment; (4) The black polyimide film with a micro-nano porous coating on the surface is stabilized to obtain the flexible film.

[0014] Preferably, in step (1): the surface activation treatment comprises: wet chemical treatment, ultraviolet radiation treatment, plasma treatment, corona treatment; Preferably, the wet chemical treatment is acid-base modification, and the base-acid modification includes base treatment and acid treatment; More preferably, the polyimide matrix is ​​treated in a 0.1-6 mol / L NaOH solution and a 0.1-6 mol / L acetic acid solution for 0.2-6 h, respectively, and then washed and dried to obtain a polymer matrix having surface active groups (hydroxyl, carboxyl or amine).

[0015] Preferably, in step (2): the concentration of the small molecule organic silicon solution is 5-50wt%; the solvent of the small molecule organic silicon solution includes: at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, ethanol, isopropanol, butanol, and tetrahydrofuran; the coating method is spraying. The temperature of the heat treatment is 25-300°C, and the time is 3-72 hours.

[0016] Preferably, in step (3): the nano oxide solution comprises: nano oxide particles, a silane coupling agent and a solvent; the solvent comprises at least one of water, an alcohol solvent and a ketone solvent; The concentration of nano-oxide particles in the nano-oxide solution is 10 to 100 mg / mL; The concentration of the silane coupling agent in the nano-oxide solution is 1 to 50 μL / mL; The heat treatment is carried out at a temperature of 25 to 300° C. and for a time of 3 to 72 hours.

[0017] Preferably, in step (4): the stabilization treatment comprises: one of ultraviolet light oxidation treatment, oxygen plasma treatment or ozone oxidation treatment and a subsequent 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 heat treatment temperature is 100-300°C and the time is 3-72 hours. The SiO-like layer rich in Si and O is formed on the outer surface of the atomic oxygen shielding layer through stabilization treatment. x Further heat treatment of the outermost surface can further reduce stress.

[0018] On the other hand, the present invention provides the application of the flexible film in the field of aerospace. In the present invention, by utilizing the characteristics of its high solar absorption ratio, the flexible film is very suitable for use in 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 eliminating stray light on the back of satellite antennas and camera barrels, and eliminates or avoids the interference of various stray lights on imaging systems and sensors; utilizing the characteristics of high solar absorption ratio and high emissivity of the flexible film, it can be widely used in the thermal control system of spacecraft to achieve 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, meeting the requirements for the long life of low-orbit spacecraft.

[0019] Beneficial effects of the present invention: The present invention provides a kind of proton oxygen-resistant / high solar absorption ratio / high emission flexible film, which has excellent resistance to space environment radiation. Its base material is a black polyimide film material, and the outermost micro-nano porous coating exposed to the space environment has excellent atomic oxygen resistance because its main skeleton is an inorganic oxide nanomaterial; between the micro-nano porous coating and the black polyimide film substrate is an organic-inorganic hybrid silicon gradient modified layer formed by the diffusion reaction on the surface of the black polyimide film substrate, and the dense modified layer has an excellent barrier effect on atomic oxygen, and the composite film layer composed of the micro-nano porous coating plays an excellent proton oxygen resistance together, which can protect the black polyimide substrate from being corroded by atomic oxygen. In addition, the inorganic oxide nanomaterials, organic-inorganic hybrid silicon materials and black polyimide matrix materials from the surface exposed to the space environment to the inside have good tolerance to ultraviolet rays, electrons and protons, so that the proton oxygen-resistant high solar absorption ratio flexible film of the present invention has the beneficial effect of resistance to space environment radiation.

[0020] The present invention provides a flexible film with anti-proton oxygen / high solar absorption ratio / high emission. On the basis of making full use of the black polyimide film, the solar absorption ratio is greatly improved. Different from the current idea of ​​using carbon nanotubes or black paint materials to achieve high solar absorption ratio, the anti-proton oxygen high solar absorption ratio flexible film of the present invention combines the matrix characteristics, surface modification and coating technology. While maintaining the high spatial environmental stability of the surface layer, it also makes full use of the optical interference effect 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, the refractive index of the composite film layer on the surface of the black polyimide matrix is ​​lower than that of the black polyimide, and the high absorption and anti-reflection effect of the carbon material on sunlight are taken into account through the gradual change of the refractive index. In addition, the multiple reflection and scattering effects of the surface micro-nano structure are used to increase the absorption of light. The solar absorption ratio of the black polyimide film is increased from about 0.92 to above 0.97. 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 the 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 overly loose structures, which will lose the firmness of the film layer and affect subsequent use and processing.

[0021] In the present invention, the bonding force between different film layers of the anti-proton oxygen high solar absorption ratio flexible film is strong, and excellent film adhesion is achieved mainly through chemical bonding, diffusion bonding and the like. In addition, the organic-inorganic hybrid silicon modified layer is formed by the in-situ diffusion reaction of small molecule silicone on the surface of the modified black polyimide matrix, and the silicon content gradually decreases from the outermost surface to the inside of the matrix, effectively avoiding the interface stress caused by the interface mutation between the organic matrix and the traditional inorganic oxide protective coating. In addition, for the outermost film layer with a high content of inorganic oxide, a porous micro-nano structure is constructed, and the flexibility of the coating material is significantly improved due to the certain micro-nano pore structure inside, and stress release is achieved, which can prevent cracking during hot and cold alternation and bending, and achieve the coordinated optimization of the film refractive index and the mechanical properties of the coating. The composite film layer composed of the modified layer and the structural layer has high bonding strength, excellent anti-peeling performance, and a firm and durable coating.

[0022] In the present invention, the nano-oxide particles in the composition of the coating nano-oxide particle mixed solution have certain replaceability to achieve functional designability. For example, conductive indium tin oxide nano-particles are used, and the alkylation treatment of the nano-oxide particles is not performed. At the same time, the amount of silane coupling agent added is controlled, and the force between the indium tin oxide particles during the heat treatment process can be used to construct a conductive network structure to prepare a porous micro-nano structure coating with a certain conductivity, thereby achieving an anti-static function and facilitating its use in higher orbits.

[0023] In the present invention, the anti-ionic oxygen high solar absorption ratio flexible film composed of a black polyimide matrix, an organic-inorganic hybrid silicon modified layer, and a porous micro-nanostructure coating has the advantage of being easy to cut and process like conventional flexible thermal control materials, and can be used in conjunction with other flexible thermal control materials. It is also easy to paste and construct, and is convenient for on-site pasting on the surface of a spacecraft, thus meeting the needs of multi-scenario use of spacecraft.

[0024] The raw materials for preparing the flexible film with anti-oxygen / high solar absorption ratio / high emission are 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 for vacuum control of conventional coating solutions, 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

[0025] Figure 1 The schematic diagram of the structure of the anti-oxygen / high solar absorption ratio / high emission flexible film disclosed in the present invention is formed by coating a small molecule organic silicon modified layer and a micro-nano porous coating on the surface of a black polyimide substrate. The outermost surface coating is composed of a skeleton composed of inorganic oxide nanoparticles, and there is a micro-nano structure with nano-scale pores between the particle skeletons, and a certain antistatic performance can be achieved by regulating the composition of the inorganic oxide nanoparticles; Figure 2 This is an electron microscope photograph of the surface of the anti-oxygen / high solar absorption ratio / high emission flexible film in Example 1. It can be seen from the figure that after the coating is formed, its microscopic micro-nano structure is formed by the arrangement of spherical or nearly spherical nanoparticles, and the agglomerates of multiple particles have certain nano-scale mesoporous pores inside, and there are larger macroporous pores between the agglomerates; Figure 3 This is an EDS image of the surface of the atomic oxygen-resistant / high solar absorption ratio / high emission flexible film in Example 1. It can be seen from the image that the coating contains four elements: silicon, carbon, nitrogen, and oxygen, of which the silicon element that can play a role in atomic oxygen protection accounts for 24.99at%; Figure 4 This is an electron microscope photograph of the surface of the anti-oxygen / high solar absorption ratio / high emission flexible film in Example 2. It can be seen from the figure that the microscopic micro-nano structure of the coating after forming is consistent with that of Example 1, and both form a porous coating with a relatively high porosity; Figure 5 This is an electron microscope photograph of the surface of the antigenic oxygen / high solar absorption ratio / high emission flexible film in Example 3. It can be seen from the figure that the surface of the modified layer is smooth after molding, without obvious micro-nanostructure features, which is quite different from Examples 1 and 2, and its corresponding solar absorption ratio is also smaller than that of Examples 1 and 2. DETAILED DESCRIPTION

[0026] 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.

[0027] In the present disclosure, the anti-proton oxygen-resistant flexible film with high solar absorption ratio comprises: an organic-inorganic hybrid silicon modified layer formed on the surface of a black polyimide substrate, a porous micro-nano structure coating formed by small molecule organic silicon and nano oxide particles, or one of the layers. Wherein, the polyimide substrate is a black polyimide substrate after surface activation treatment with carboxyl, hydroxyl or amine groups. Preferably, the anti-proton oxygen-resistant flexible film with high solar absorption ratio comprises: a black polyimide substrate after surface activation treatment, an organic-inorganic hybrid silicon modified layer formed on the surface of the black polyimide substrate, and a porous micro-nano structure coating formed by bonding nano oxide particles and silane coupling agents.

[0028] In the present invention, the organic-inorganic hybrid silicon modified layer is a dense film layer formed by the in-situ diffusion reaction of small molecule organic silicon on the surface of the modified black polyimide substrate. It has excellent barrier properties and plays a role in protecting the black polyimide substrate. The silicon content gradually decreases from the outermost surface to the inside of the substrate, effectively avoiding the atomic oxygen protection failure caused by the interface mutation between the organic substrate and the traditional inorganic oxide protective coating, and has excellent anti-proton oxygen performance. The atomic oxygen-resistant micro-nano porous coating is composed of a skeleton composed of inorganic oxide nanoparticles and a silane coupling agent. It is a micro-nano structure with nanopores, and its flexibility is significantly improved, and the anti-cracking performance is excellent. It also has excellent resistance to atomic oxygen erosion and good stability in the space environment. At the same time, the micro-nano porous coating has the characteristics of replaceable nano-skeleton composition. In addition to reducing the reflectivity to achieve a high solar absorption ratio, it can further meet the functional requirements of anti-static and the like. Moreover, the raw materials and preparation price of this anti-atomic oxygen high solar absorption ratio flexible film are relatively low, easy to implement and operate, and can be widely used in the aerospace field, especially in low-orbit spacecraft affected by atomic oxygen corrosion, compared with traditional flexible film raw materials.

[0029] In an optional embodiment, the organic-inorganic hybrid silicon modified layer is a chemically bonded gradient layer structure of small molecule organic silicon on the surface of a black polyimide substrate. The porous micro-nano structure coating is composited with a silane coupling agent and nano silicon oxide; and under the condition of meeting the coating firmness requirements, the porosity of the porous micro-nano structure coating is as high as possible, for example, the porosity is 20% to 90%, and the refractive index decreases from the black polyimide substrate, the organic-inorganic hybrid silicon modified layer to the porous micro-nano structure coating, and the purpose of reducing reflection and increasing the solar absorption ratio is achieved by gradually changing the refractive index from low to high.

[0030] In the present invention, the interaction force between the organic-inorganic hybrid silicon modified layer and the black polyimide matrix mainly comes from the chemical bonding between the small molecule organic silicon with amine groups and the modified matrix with carboxyl groups or hydroxyl groups, the chemical bonding between the small molecule organic silicon with siloxane and the modified matrix with carboxyl groups or hydroxyl groups, and the gradient bonding of the surface diffusion of the small molecule organic silicon. The porous micro-nano structure coating formed by bonding the nano oxide particles and the silane coupling agent mainly comes from the bonding action between the silane coupling agent and the modified layer, and the bonding action between the small molecule organic silicon in the modified layer and the nano oxide particles. The surface layer can be functionally designed with atomic oxygen resistant micro-nano porous coating materials. The coating can be coated on other surfaces that are anti-proto-oxygen as a functional layer, and can also be directly coated on the surface of a black polyimide substrate to simultaneously play the role of anti-proto-oxygen and other functions, such as antistatic effect. When the atomic oxygen resistant micro-nano porous coating is directly coated on the surface of a black polyimide substrate, the silane coupling agent should contain functional groups that can chemically bond to the black polyimide substrate or the surface of the black polyimide substrate after surface activation treatment.

[0031] In an optional embodiment, the modified black polyimide matrix having carboxyl, hydroxyl or amine groups is prepared by surface activation treatment of black polyimide containing imide rings; the surface activation treatment includes: wet chemical treatment, ultraviolet radiation treatment, plasma treatment, corona treatment, etc.; preferably, the surface of the polymer matrix is ​​subjected to alkali-acid modification; the alkali-acid modification includes alkali treatment and acid treatment. More preferably, the polymer matrix 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 having surface active groups (hydroxyl, carboxyl).

[0032] In an optional embodiment, the organic-inorganic hybrid silicon modified layer formed on the surface of the black polyimide substrate is a chemically bonded gradient layer structure formed by the reaction and diffusion of small molecule organic silicon on the substrate surface.

[0033] In an optional embodiment, the porous micro-nanostructure coating is formed by bonding nano-oxide particles and a silane coupling agent, wherein the nano-oxide particles include at least one of silicon dioxide, indium tin oxide, and zinc oxide; the nano-oxide particles are spherical nano-particles or quasi-spherical nano-particles with a particle size of 7nm to 30nm. Preferably, the organosilicon coupling agent is selected from at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-aminoethyl-3-aminopropyltriethoxysilane, and 3-aminopropylmethyldiethoxysilane, preferably 3-aminopropyltriethoxysilane. Preferably, the ratio of the nano-oxide particles to the silane coupling agent is (25 to 150) mg: (0 to 10) μL. Preferably, the ratio of the nano-oxide particles to the silane coupling agent is 50 mg: (0 to 10) μL, and preferably the content of the silane coupling agent is not 0. More preferably, the ratio of the nano-oxide particles to the silane coupling agent is 50 mg: (1-10) μL.

[0034] In an optional embodiment, the obtained anti-proton oxygen high solar absorption ratio flexible 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.

[0035] The following is an exemplary description of the method for preparing an antigenic oxygen-resistant high solar absorption ratio flexible film.

[0036] 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%.

[0037] Preparation of organic-inorganic hybrid silicon modified layer. The small molecule organic silicon solution is coated on the surface of the black polyimide substrate after surface activation treatment, and then a high temperature heat treatment is performed at 25 to 300°C to prepare a chemically bonded organic-inorganic hybrid silicon gradient layer structure. The chemical formula of the silane is (YR) n SiX 4-n , 1≤n≤3, wherein Y is a carbon functional group that can react with the modified black polyimide matrix, preferably at least one of unsaturated isocyanate, amine and cyano; X is a silicon functional group that can react and bond with the porous micro-nanostructure coating, preferably at least one of alkoxy, halide, acyloxy and silanol. At the same time, the silicon functional group can also polymerize with the carboxyl and hydroxyl groups in the modified black polyimide matrix or the silicon functional groups can further bond with each other to form a dense modified layer by cross-linking, achieving excellent anti-proton oxygen performance. Considering the lightweight design of the spacecraft and the problem that the increase in the thickness of the film layer is prone to cracking, the thickness of the organic-inorganic hybrid silicon modified layer does not exceed 50μm.

[0038] Preparation of micro-nano porous coating. After mixing nano-oxide particles and solvent, a silane coupling agent is added to the nano-oxide particle dispersion to obtain a mixed solution, and the mixed solution is applied to the surface of a modified black polyimide substrate having a carboxyl group to form a wet film, and heat-treated in an air atmosphere to obtain an atomic oxygen-resistant micro-nano porous coating. Preferably, the solvent is selected from at least one of water, alcohol, and ketone; the ketone is a ketone solvent containing a ketone carbonyl group, preferably at least one of acetone, butanone, methyl isobutyl ketone, and cyclohexanone. Preferably, the nano-oxide particles can be added with a surface modifier for ultrasonic treatment and stirring treatment to complete the alkylation treatment to better disperse the nano-oxide particles, avoid their sedimentation, and extend the storage and use cycle of the nano-oxide particle dispersion; preferably, the frequency of the ultrasonic treatment is greater than 30kHz, and the time is greater than 1h; the speed of the stirring treatment is 200-400rpm, and the time is 2-22 hours; the total time of the ultrasonic treatment and stirring treatment = the total time of alkylation, which is 4-24 hours, preferably 12h. Preferably, the coating method includes: one of spin coating, drip coating, spray coating, scraping coating, static pulling, and wire rod coating; preferably, the temperature of the heat treatment is a temperature value within 80 to 250°C or a gradient temperature formed by two or more temperature values, and the total treatment time is 3 to 24 hours. The thickness of the atomic oxygen-resistant micro-nano porous coating does not exceed 50 μm. The particle size of the nano oxide can be spherical or quasi-spherical nanoparticles with one or more diameters within the range of 7 to 50 nm. The above-mentioned nano oxide is replaceable so that different functionalizations can be achieved. The nano powder is an oxide and a doped powder based on these oxides, including but not limited to: silicon dioxide, indium tin oxide, etc. The silane coupling agent mainly refers to an aminohydrocarbon silane with an amino group, which is a mixture of one or more of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-aminoethyl-3-aminopropyltriethoxysilane, and 3-aminopropylmethyldiethoxysilane in any proportion. A preferred aminohydrocarbylsilane is 3-aminopropyltriethoxysilane.

[0039] 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 SiO-like layer rich in Si and O can be further formed on the outer surface of the atomic oxygen protective layer by stabilization treatment. x Outermost surface.

[0040] In one embodiment of the present invention, nano oxide powder is dispersed in a suitable solvent to obtain a well-dispersed dispersion. After adding a certain amount of aminosilane as a cross-linking agent to the above dispersion, it is coated on a black polyimide substrate or other coating surface modified by alkali / acid to form a wet film, and finally heat-treated in an air atmosphere to obtain a functionally designed atomic oxygen-resistant micro-nano porous coating.

[0041] Spherical silica with a particle size of 15 nm, hexamethyldisilazane, acetone, 3-aminopropyltriethoxysilane, and alkali-acid modified black polyimide film are used as oxide nanopowder, surface modifier, solvent, cross-linking agent, and black polyimide matrix, respectively, to illustrate a method for preparing a functionally designed atomic oxygen-resistant micro-nano porous coating.

[0042] The oxide nanopowder is dispersed in a suitable dispersing solvent, and after adding a surface modifier, the powder surface is modified by ultrasonication and stirring to obtain a well-dispersed nanopowder dispersion. Among them, the ratio of the oxide nanopowder to the dispersing solvent is 5-30 mg / mL, and the preferred mass concentration is 10 mg / mL. The ratio of the surface modifier to the solvent is 2-20 μL / mL, preferably 10 μL / mL. The ultrasonic process should be processed at a frequency greater than 30kHz, and the time is greater than 1h. 1h each time at 60kHz, a total of 2 times is appropriate. Specifically, the preparation of a well-dispersed silica solution includes: stirring 25-150mg (for example, 50mg) of 15nm silica powder into 5mL acetone. Then, 10-100μL (for example, 50μL) of hexamethyldisilazane is added. After ultrasonic dispersion at room temperature and 60kHz for 1h, stirring at 300rpm for 12h, and then ultrasonicating for 1h, a well-dispersed silica solution can be obtained.

[0043] After adding a certain amount of aminosilane as a crosslinking agent to the above oxide nanopowder dispersion, it is coated on the surface of the alkali / acid modified black polyimide substrate or other anti-proton oxygen coating to form a wet film, and finally heat-treated in an air atmosphere to obtain a functionally designed atomic oxygen-resistant micro-nano porous coating. The ratio of the amount of crosslinker aminosilane added to the solvent can be 0 to 2 μL / mL, preferably 1 μL / mL. According to the above scheme, the method of alkali / acid two-step modification of the black polyimide substrate is to place the substrate in a 1 mol / L sodium hydroxide solution for modification for 1 hour, and repeatedly wash it with deionized water and anhydrous ethanol to remove the residual alkali solution; then place it in a 1 mol / L acetic acid solution for modification for 1 hour, and after the modification is completed, use deionized water and anhydrous ethanol to repeatedly wash it to remove the residual acid solution. Finally, dry it in the air for use.

[0044] Specifically, 0 to 10 μL (for example, 5 μL) of 3-aminopropyltriethoxysilane is added to the above-mentioned well-dispersed silica solution. After stirring for 10 minutes, 4 drops of solution are added each time and spin-coated on a 20×20mm alkali-acid modified black polyimide film substrate at a speed of 1000 rpm for 12 seconds, for a total of 6 spin-coatings, and then placed in an air atmosphere at 80, 110, and 150°C for heat treatment for 1h, 1h, and 3h, respectively. Finally, the above-mentioned functionally designed atomic oxygen-resistant micro-nano porous coating can be obtained. Among them, the coating method, in addition to the spin coating method, can be any one of the drop coating method, spray coating method, scraping method, or static pulling method.

[0045] The advantages of the method of the present invention are: using commercially available nano oxide powder (such as silicon dioxide) as raw material, the raw material has a wide range of types and particle sizes to choose from, and the price is low; by modifying the surface of the nano oxide (such as silicon dioxide), its dispersibility is greatly improved, so that the film is uniform and no obvious agglomeration occurs. The use of amino hydrocarbon silane coupling agent not only increases the bonding between nano particles, so that the flexibility of the coating is significantly improved, but also produces a strong bond between the coating and the surface of the black polyimide after surface modification, which significantly improves the adhesion of the coating. The present invention is based on a novel strategy for regulating the micro-nano structure of the anti-atomic oxygen coating. The coating involved is composed of a skeleton composed of inorganic oxide nanoparticles, and is a micro-nano structure with nanopores. Its flexibility is significantly improved, and it has excellent anti-cracking performance and excellent anti-atomic oxygen corrosion performance. At the same time, the coating has the characteristics of replaceable nano-skeleton composition, which can meet the functional requirements of the anti-atomic oxygen coating such as anti-transmission and anti-static. Moreover, its raw materials and preparation are inexpensive, easy to implement and operate, and can be widely used in low-orbit spacecraft affected by atomic oxygen corrosion in the aerospace field.

[0046] Performance Test: Scanning electron microscope was used to observe the surface morphology of the sample. 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 tensile force 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°) with a cylindrical bending tester with a bending diameter of 2mm; refer to GJB 2502.8 Test Methods for Thermal Control Coatings of Spacecraft Part 8: Thermal Cycle Test Carry out hot and cold alternating test to check the appearance and thermal radiation performance after 100 high and low temperature alternations at -110℃~+150℃; refer to GJB2704 General Specifications for Thermal Control Coatings of Spacecraft to carry out wet heat test to check the appearance and thermal radiation performance after 50℃, 95%RH, 24h; refer to GJB 2502.5 Test Methods for Thermal Control Coatings of Spacecraft Part 5: Vacuum-Ultraviolet Irradiation Test to carry out ultraviolet irradiation test to check the thermal radiation performance after vacuum-Ultraviolet irradiation test with a cumulative dose of 2000ESH; refer to GJB 2502.7 Test Methods for Thermal Control Coatings of Spacecraft Part 7: Vacuum-Electron Irradiation Test to check the 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 Accumulated Dose 2.5×10 15 p / cm 2 The thermal radiation performance after proton irradiation test; refer to GJB 2502.9 Test Method for Thermal Control Coatings of Spacecraft Part 9: Atomic Oxygen Test to carry out atomic oxygen irradiation test, and check the cumulative dose of 2.61×10 21 atoms / cm 2 The mass loss and thermal radiation performance after atomic oxygen irradiation test; refer to GJB 2704A General Specification for Thermal Control Coatings of Spacecraft and QJ1558B Test Method for Volatility Performance of Materials under Vacuum Conditions. Test pressure ≤7.0×10 -3 Pa, vacuum volatility after maintaining for 24 hours under the conditions of temperature of 125°C; refer 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, and observe the appearance with the naked eye after wiping 3 times to test its cleaning resistance.

[0047] 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.

[0048] Example 1 According to the technical solution of the present invention, a kind of anti-oxygen / high solar absorption ratio / high emissivity flexible film material is prepared: (1) Preparation of the active layer on the surface of the black polyimide substrate. 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 black polyimide 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 an alkaline solution of 1 mol / L sodium hydroxide for 1 hour, and then the residual alkaline solution was rinsed with deionized water and ethanol. The rinsed PI film was then placed in an acid solution of 1 mol / L acetic acid 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 organic-inorganic hybrid silicon modified layer. Prepare an ethanol solution containing 20 wt% of 3-aminopropyltriethoxysilane and 20 wt% of 3-aminopropylmethyldiethoxysilane as a small molecule organic silicon solution for spraying as a surface modification solution. Spray it on the surface of the black polyimide substrate after surface activation treatment; (3) Preparation of micro-nano porous coating. When the nano oxide is silicon dioxide, the coating system uses acetone as solvent, wherein the concentrations of silicon dioxide, surface modifier hexamethyldisilazane, and 3-aminopropyltriethoxysilane are 30 mg / mL, 30 μL / mL, and 10 μL / mL, respectively (by mixing two silane coupling agents, the concentration is increased and the firmness is increased). 3 g of 15 nm silicon dioxide powder is stirred and added to 100 mL of acetone. Then 30 μL of hexamethyldisilazane is stirred and added for surface modification. The above-mentioned mixed solution is ultrasonically dispersed and stirred to obtain an acetone solution of silicon dioxide. 5 μL of 3-aminopropyltriethoxysilane is added to the solution. After stirring, it is coated on the surface of the surface-modified black polyimide film, and then it is placed in an air atmosphere at 60°C, 90°C, 120°C, and 150°C for heat treatment for 1h, 1h, 3h, and 3h, respectively, to obtain an atomic oxygen-resistant micro-nano porous coating; (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 0.5 hours; 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.

[0049] A systematic material performance and environmental adaptability test was conducted on the anti-oxygen / high absorption / high emission flexible thin film material prepared according to the above steps. The results show that the treated surface has a dark matte 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 micro-nano porous structure, and the Si content of the EDS test is about 24.99at%, which is slightly higher than the Si content of the sample obtained in step (3) (23.84at%), 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 about 0.98, and the hemispherical emissivity ε H The thermal radiation performance of the sample obtained in step (3) is about 0.91, which is not much different from that of the sample obtained in step (3). The thermal radiation performance of the sample has a high solar absorption ratio and a high hemispherical emissivity, and the thermal radiation performance of the sample with a high solar absorption ratio and a high hemispherical emissivity is less affected by the stabilization treatment. After the 3M610 pull-off test, the film layer has no blistering or obvious shedding on the surface, and the film layer has good adhesion. After the bending test (180° 1000 times) with a cylindrical bending tester having a bending diameter of 2 mm, the film layer has no obvious shedding, and the peeling and cracking resistance is excellent. The thermal radiation performance of the sample obtained in step (3) has a high solar absorption ratio and a high hemispherical emissivity, and the thermal radiation performance of the sample with a high solar absorption ratio and a high hemispherical emissivity is less affected by the stabilization treatment. The test was repeated for 100 times, with a stay time of 5 minutes at the high and low temperature ends, and a transfer time of less than 10s. After the test, the appearance was intact, without blistering, peeling, or shedding. There was no significant change in the solar absorption ratio and hemispherical emissivity before and after the test, and the performance of hot and cold alternation resistance was excellent. After the ground wet heat test (50℃±2℃, 95%±5%RH, 24h), the appearance was intact, without blistering, peeling, shedding, or corrosion. There was no significant change in the solar absorption ratio and hemispherical emissivity before and after the test, and the sample had good storability. The vacuum degree was 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 (15keV: 1.9×10 15 e / cm 2 ; 40keV: 0.6×10 15e / 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 15 p / cm 2 After the (50keV) energy irradiation test, the solar absorption ratio of the in-situ test decreased by about 0.01 compared with that before the test, and the hemispherical emissivity did not change significantly, which showed good resistance to proton irradiation. 21 atoms / cm 2 After atomic oxygen irradiation, the mass loss per unit area is 0.03 mg / cm 2 , the solar absorption ratio and hemispherical emissivity have no obvious changes, and the substrate is intact without any signs of corrosion, indicating that the composite film layer constructed on the surface of the black polyimide substrate has excellent anti-oxygen performance; after the vacuum volatilization test, the total mass loss (TML) of the sample is 0.78%, the condensable volatile matter (CVCM) is 0.01%, and the water vapor reabsorption (WVR) is 0.40%, which meets the general use requirements of thermal control coatings, and is 1 order of magnitude lower than the condensable volatile matter (CVCM) ≤ 1% in the GJB 2704A general specification for spacecraft thermal control coatings. In addition, the sample also has a certain degree of cleaning resistance. After being lightly wiped 3 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 is dark black in 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.

[0050] Example 2 The preparation process of the antiproto-oxygen / high solar absorption ratio / high emissivity flexible film in Example 2 is similar to that in Example 1, except that step (2) is removed, i.e., no additional preparation of an antiproto-oxygen organic-inorganic hybrid silicon modified layer is performed. The results show that the treated surface of the prepared sample has a dark black matte 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 micro-nano porous structure, and the Si content is about 21.02at%; the solar absorption ratio α s is about 0.97, and the hemispherical emissivity ε HThe invention discloses a method for preparing a black polyimide substrate having a surface area of ​​200 nm and a surface area of ​​100 nm, wherein the surface area of ​​the black polyimide substrate has a surface area of ​​200 nm and a surface area of ​​100 nm. The invention discloses a method for preparing a black polyimide substrate having ... There is no significant change in the solar absorption ratio and hemispherical emissivity of the sample before and after thermal cycle test, ground humidity test, ultraviolet irradiation, electron irradiation, and proton irradiation. 21 atoms / cm 2 After the atomic oxygen test, the mass loss per unit area is 0.22 mg / cm 2 , the solar absorption ratio and hemispherical emissivity have no obvious changes. Compared with Example 1, there is a certain mass loss of atomic oxygen, but the substrate is still intact, and compared with the original black polyimide substrate, the erosion rate is reduced by more than 40 times, and the erosion situation is greatly improved, indicating that the micro-nano porous coating also plays a certain protective role on the black polyimide substrate. This method of directly constructing a micro-nano porous coating on the surface of the black polyimide substrate is simpler than constructing a two-layer composite film layer. It is recommended that it can be promoted and applied in orbits or service life situations where the atomic oxygen protection performance is not too high, and it has the advantages of simpler process and lower cost than a two-layer composite film layer.

[0051] Example 3 The preparation process of the atomic oxygen-resistant high solar absorption ratio flexible film in Example 3 is similar to that in Example 1, except that step (3) is removed, i.e., there is no surface atomic oxygen-resistant micro-nano porous coating. The results show that the treated surface of the prepared sample has a good appearance of dark black, has excellent firmness, but is in a bright state; under a scanning electron microscope, the surface is smooth and flat ( Figure 5 ), Si content is about 16.16at%; solar absorption ratio α s About 0.94~0.95, hemispherical emissivity ε HThe sample has excellent space environment stability. The solar absorption ratio and hemispherical emissivity have no significant changes before and after thermal cycle test, ground humidity test, ultraviolet irradiation, electron irradiation, and proton irradiation. 22 atoms / cm 2 After the atomic oxygen test, the mass loss per unit area is -0.01 mg / cm 2 The solar absorption ratio decreased by about 0.01 compared with that before the test, and the hemispherical emissivity had no obvious change. The extremely slight weight gain and change in the solar absorption ratio may be caused by test errors or extremely small amounts of excess deposition during the long-term test process. At the same time, the surface of the sample under the optical microscope or electron microscope was smooth and had no traces of atomic oxygen corrosion, and the substrate was intact without any signs of corrosion, indicating that the dense organic-inorganic hybrid silicon modified layer formed by the in-situ diffusion reaction on the surface of the black polyimide matrix has excellent barrier properties and plays a role in protecting the black polyimide matrix.

[0052] Example 4 The preparation process of the atomic oxygen resistant micro-nano porous coating in Example 4 is similar to that in Example 1, except that the SiO2 particle size is 40 nm. The coating prepared by 40 nm silicon dioxide also has a high solar absorption ratio (α s About 0.96 to 0.97), high hemispherical emissivity (ε H The thermal radiation performance of the sample is about 0.91), but the uniformity of the sample appearance is slightly poor. At the same time, if the acetone solution of the silica is not surface-modified by hexamethyldisilazane, it is easy to settle, which is not conducive to industrial production.

[0053] Example 5 The preparation process of the atomic oxygen resistant micro-nano porous coating in this Example 5 refers to that in Example 1, the only difference is that the SiO2 particle size is 50 nm. When 50 nm silicon dioxide is used, the uniformity of the prepared coating is poor, and there is a whitening phenomenon caused by particle agglomeration in some areas, which affects the solar absorption ratio. At the same time, the acetone solution of the prepared silicon dioxide is easy to settle, which is not conducive to industrial production.

[0054] Example 6 The preparation process of the atomic oxygen-resistant high solar absorption ratio flexible thin film material in Example 6 refers to Example 1, with the only difference being that the preparation process of the atomic oxygen-resistant micro-nano porous coating is different, specifically, 3-aminopropyltriethoxysilane is not added. In this embodiment, the bonding strength between the coating without 3-aminopropyltriethoxysilane and the substrate is reduced, and some areas are easily peeled off by the 3M610 tape, but it is still suitable for scenes with relatively low requirements for the firmness of the film layer.

[0055] Example 7 The preparation process of the atomic oxygen-resistant high solar absorption ratio flexible film material in Example 7 is similar to that in Example 1, except that the preparation process of the atomic oxygen-resistant micro-nano porous coating is different, and the surface modifier hexamethyldisilazane is not added during the preparation. In this example, a high solar absorption ratio film layer with excellent film firmness can also be obtained. Solar absorption ratio α s In addition, it was found during the implementation that the atomic oxygen resistant micro-nano porous coating mixed solution in this embodiment has poor dispersibility, is easy to settle, and is not suitable for long-term storage. The storage period of the prepared solution needs to be considered during industrial continuous implementation.

[0056] Example 8 The preparation process of the atomic oxygen resistant micro-nano porous coating in Example 8 is similar to that in Example 1, except that the SiO2 particle size is 7 nm. The coating prepared by 7 nm silicon dioxide also has a high solar absorption ratio (α s About 0.97 to 0.98), high hemispherical emissivity (ε H The thermal radiation performance is about 0.91).

[0057] Example 9 The preparation process of the atomic oxygen resistant micro-nano porous coating in Example 9 is similar to that in Example 1, except that the SiO2 particle size is 12 nm. The coating prepared by 12 nm silicon dioxide also has a high solar absorption ratio (α s About 0.97 to 0.98), high hemispherical emissivity (ε H The thermal radiation performance is about 0.91).

[0058] Example 10 The preparation process of the atomic oxygen resistant micro-nano porous coating in Example 10 is similar to that in Example 1, except that the SiO2 particle size is 20 nm. The coating prepared by 20 nm silicon dioxide also has a high solar absorption ratio (α s About 0.96 ~ 0.98), high hemispherical emissivity (ε H The thermal radiation performance is about 0.91).

[0059] Example 12 The preparation process of the atomic oxygen resistant micro-nano porous coating in Example 12 is similar to that in Example 1, except that the preparation process of the micro-nano porous coating is different. Specifically, the silicon dioxide nanopowder is replaced with hollow silicon dioxide. The prepared film layer also has a relatively loose micro-nano porous structure, has better adhesion and flexibility, and at the same time, the solar absorption ratio of the sample is α s Compared with Example 1, it is slightly improved to about 0.98, mainly because the hollow silica can further reduce the refractive index of the micro-nano porous coating, reduce reflection, and increase the solar absorption ratio.

[0060] Embodiment 13 The preparation process of the high solar absorption ratio flexible film resistant to proton oxygen in this embodiment 13 refers to that in embodiment 1, and the only difference is that the preparation process of the micro-nano porous coating is different. Specifically, the nano powder is replaced with indium tin oxide (ITO), APTES and hexamethyldisilazane are not added, the solvent is water, and the matrix is ​​a black polyimide matrix of an organic-inorganic hybrid silicon modified layer resistant to proton oxygen. The prepared ITO functional layer also has a relatively loose micro-nano porous structure, with excellent adhesion and flexibility. At the same time, the conductive network constructed by the ITO nanoparticles gives the film layer a certain antistatic function, and its square resistance is about 300kΩ / □, which varies in different regions, but can meet the application requirements of antistatic aerospace thermal control coatings.

[0061] Comparative Example 1 The commercial black polyimide film (HB-N-25 product of Shenzhen Ruihuatai Film Technology Co., Ltd.) used in the present invention has a solar absorption ratio of 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 2 The 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.

[0062] 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.

[0063] Comparative Example 3 See Example 2, the difference is: a conventional 25 μm 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.

[0064] Comparative Example 4 See Example 3, 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 0.24-0.25, and the hemispherical emissivity is about 0.53; 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.

[0065] The raw materials listed in the present invention, as well as the upper and lower limits and interval values ​​of the raw materials in 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.

[0066] 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. A flexible film, characterized in that: include: A black flexible substrate, and an organic-inorganic hybrid silicon modified layer and / or a porous micro-nano structure coating sequentially formed on the surface of the black flexible substrate; The black flexible substrate comprises a black polyimide film, a black polyester film or a black polyethylene film; Preferably, the solar absorption ratio α of the black flexible substrate is s ≥0.88, hemispherical emissivity ε H ≥0.

78.

2. The flexible film according to claim 1, characterized in that: include: A black flexible substrate, and an organic-inorganic hybrid silicon modified layer and a porous micro-nano structure coating which are sequentially formed on the surface of the black polyimide substrate.

3. The 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.

4. The 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.

5. The flexible film according to claim 4, characterized in that: The surface activation treatment includes: wet chemical treatment, ultraviolet radiation treatment, plasma treatment, corona treatment; preferably, the wet chemical treatment is acid-base modification, and the alkali-acid modification includes alkali treatment and acid treatment; more preferably, the polyimide matrix 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 hours, respectively, and then washed and dried to obtain a polymer matrix with surface active groups (hydroxyl, carboxyl or amine).

6. The flexible film according to claim 1, characterized in that: The organic-inorganic hybrid silicon modified layer is a chemically bonded gradient structure layer formed by the reaction and diffusion of small molecule organic silicon on the surface of the black polyimide matrix; the chemical formula of the small molecule organic silicon is (YR) n SiX 4-n , 1≤n≤3, wherein Y is a carbon functional group capable of reacting with a modified black polyimide matrix, preferably at least one of an unsaturated isocyanate, an amine and a cyano group; X is a silicon functional group capable of reacting and bonding with the porous micro-nanostructure coating, preferably at least one of an alkoxy group, a halide group, an acyloxy group and a silanol group.

7. The flexible film according to any one of claims 1 to 6, characterized in that: The porous micro-nano structure coating is composed of nano oxide particles and a silane coupling agent; The nano-oxide particles are spherical nano-particles or quasi-spherical nano-particles with a particle size of 7nm to 40nm; The nano-oxide particles are spherical nano-particles or quasi-spherical nano-particles, and the particle size of 7nm to 40nm is mixed with the particle size of 50nm, and the amount of the particle size of 50nm added does not exceed 50%; The organosilicon coupling agent is selected from at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-aminoethyl-3-aminopropyltriethoxysilane, and 3-aminopropylmethyldiethoxysilane, preferably 3-aminopropyltriethoxysilane.

8. The flexible film according to claim 7, characterized in that: The ratio of the nano-oxide particles to the silane coupling agent is (2-100) mg: (0-10) μL; Preferably, the ratio of the nano-oxide particles to the silane coupling agent is 50 mg: (0-10) μL and the content of the silane coupling agent is not 0; More preferably, the ratio of the nano-oxide particles to the silane coupling agent is 50 mg: (1-10) μL.

9. A method for preparing a flexible film according to any one of claims 1 to 8, characterized in that: When the black flexible substrate is a black polyimide film, the preparation method comprises: (1) Surface activation treatment of black polyimide substrate; (2) coating a small molecule silicone solution on the surface of a black polyimide substrate after surface activation treatment, and obtaining a surface-modified black polyimide film through heat treatment; (3) coating the nano-oxide solution on the surface of the surface-modified black polyimide film, and obtaining a micro-nano porous coating by heat treatment; (4) The black polyimide film with a micro-nano porous coating on the surface is stabilized to obtain the flexible film.

10. The preparation method according to claim 9, characterized in that: In step (1): the surface activation treatment includes: wet chemical treatment, ultraviolet radiation treatment, plasma treatment, corona treatment; Preferably, the wet chemical treatment is acid-base modification, and the base-acid modification includes base treatment and acid treatment; More preferably, the polyimide matrix is ​​treated in a 0.1-6 mol / L NaOH solution and a 0.1-6 mol / L acetic acid solution for 0.2-6 h, respectively, and then washed and dried to obtain a polymer matrix having surface active groups (hydroxyl, carboxyl or amine).

11. The preparation method according to claim 9, characterized in that: In step (2): the concentration of the small molecule organosilicon solution is 5 to 50 wt %; The solvent of the small molecule organic silicon solution includes: at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, ethanol, isopropanol, butanol, and tetrahydrofuran; The coating method is spraying; The heat treatment is carried out at a temperature of 25 to 300° C. and for a time of 3 to 72 hours.

12. The preparation method according to claim 9, characterized in that: In step (3), the nano-oxide solution comprises nano-oxide particles, a silane coupling agent and a solvent; the solvent comprises at least one of water, an alcohol solvent and a ketone solvent; The concentration of nano-oxide particles in the nano-oxide solution is 10 to 100 mg / mL; The concentration of the silane coupling agent in the nano-oxide solution is 1 to 50 μL / mL; The heat treatment is carried out at a temperature of 25 to 300° C. and for a time of 3 to 72 hours.

13. The preparation method according to any one of claims 9 to 12, characterized in that: In step (4), the stabilization treatment includes: one of ultraviolet light oxidation treatment, oxygen plasma treatment or ozone oxidation treatment and a subsequent heat treatment process to reduce stress; 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 UV light intensity of the ultraviolet light oxidation treatment is 2 to 15 mW / cm 2 , time is 1 to 24 hours; The heat treatment temperature is 100 to 300° C. and the time is 3 to 72 hours.

14. Use of the flexible film according to any one of claims 1 to 8 in the aerospace field.

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