Thermal control film and preparation method and application thereof
By using a combination of thermoplastic fluororesin, inorganic thermally controlled filler and vapor-phase silica in thermally controlled films, the existing thermally controlled coating/film layer molding instability and long-term stability problems are solved, and efficient temperature control and environmentally friendly preparation processes are achieved.
Patent Information
- Application Number
- CN202510075775.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-17
- Publication Date
- 2025-05-23
AI Technical Summary
The existing thermally controlled coatings/film layers have molding instability and long-term stability problems in solar radiation and low temperature environments, which affect the temperature control of the spacecraft.
The preparation method of thermally controlled films is adopted, including thermoplastic fluororesin, inorganic thermally controlled fillers and vapor-phase silica. Through uniform mixing and granulation casting technology, the molding stability and long-term stability of the film are improved.
The high hemispherical emissivity and low solar absorption ratio of the thermally controlled film are achieved, which improves the temperature control capability of the spacecraft. The method is solvent-free, low energy consumption and more environmentally friendly.
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Abstract
Description
Technical Field
[0001] This application relates to the field of aerospace technology, and particularly to a thermal control film, a preparation method thereof, and an application thereof. Background Art
[0002] With the progress of human civilization and technology, the exploration of space by humans has never stopped. Spacecraft are one of the most important tools for humans to explore space, and their in-orbit operation safety and reliability will directly determine the success or failure of space missions. During the operation of satellites in the space environment, they are subjected to the alternating action of heat and cold from the sun, planets, and the low-temperature space environment, and the temperature change range can reach ±200°C. This will inevitably cause drastic high and low temperature changes on the inner and outer surfaces of the spacecraft and its instrument equipment, and it is extremely easy to cause damage or even failure of the spacecraft functions. Thermal control plays a crucial role in the reliability and safety of spacecraft. Controlling the surface temperature of the spacecraft within an appropriate range is a key factor to ensure the normal operation of precision instruments and equipment in the cabin.
[0003] In order to effectively reduce the equilibrium temperature of in-orbit satellites facing solar radiation, low-absorptance and high-emittance thermal control coatings / films are currently the most effective and widely used type of thermal control coatings / films. Low-absorptance and high-emittance thermal control coatings / films have a low solar absorptance (α s ) and a high infrared hemispherical emittance (ε H ). Among them, the solar absorptance is the ratio of the absorbed solar radiant energy flux to the incident solar radiant energy flux, and the hemispherical emittance is the ratio of the heat radiated by a thermal radiator in the hemispherical space to the heat radiated by a black body at the same temperature. The solar absorptance and the hemispherical emittance are the most important thermophysical properties for regulating the surface temperature of spacecraft, and they are of great significance for the thermal design of satellites. Summary of the Invention
[0004] In view of this, an object of this application is to provide a thermal control film and a preparation method thereof, so that the thermal control film has a high hemispherical emittance and a low solar absorptance, while improving the forming stability and long-term stability of the thermal control film, which is beneficial to the temperature control of spacecraft;
[0005] Another object of this application is to provide the application of the above thermal control film in the field of manufacturing spacecraft, and at the same time provide a spacecraft based on the thermal control film.
[0006] To solve the above technical problems / achieve the above object or at least partially solve the above technical problems / achieve the above object, as the first aspect of this application, a thermal control film is provided, which includes a thermoplastic fluororesin, an inorganic thermal control filler, and fumed silica.
[0007] Optionally, the thermal control film comprises, by weight, 100 parts of thermoplastic fluororesin, 50-80 parts of inorganic thermal control filler and 1-8 parts of fumed silica.
[0008] Optionally, the thermoplastic fluororesin includes ethylene-tetrafluoroethylene copolymer or poly(perfluoroethylene-propylene).
[0009] Optionally, the inorganic thermal control filler includes one or more of zinc titanate, calcium fluoride, sodium fluoride, and zirconium fluoride. Further optionally, the inorganic thermal control filler includes zinc titanate, and one or more of calcium fluoride, sodium fluoride, and zirconium fluoride.
[0010] As a second aspect of the present application, a method for preparing the thermal control film is provided, comprising:
[0011] The inorganic thermal control filler and the fumed silica are uniformly mixed to obtain a mixed filler;
[0012] The mixed filler is mixed with the thermoplastic fluororesin and then granulated to obtain a primary masterbatch;
[0013] The thermal control film is obtained by tape casting using the primary masterbatch as a raw material.
[0014] Optionally, the temperature of the tape casting is 280-320° C., and the extrusion pressure is 10-15 MPa.
[0015] As a third aspect of the present application, there is provided application of the thermal control film in the preparation of spacecraft.
[0016] Optionally, the spacecraft includes one or more of an artificial satellite, a space station, a space shuttle, an aerospace plane, and a space probe.
[0017] As a fourth aspect of the present application, a spacecraft is provided, the surface and / or interior of which comprises the thermal control film described in the present application.
[0018] The present application uses fumed silica as the anode protection filler of the thermal control film to improve the compatibility of the inorganic thermal control filler with the fluororesin, thereby improving the molding stability and long-term stability of the thermal control film, while having both a higher hemispherical emissivity and a lower solar absorption ratio, which is beneficial to the temperature control of the spacecraft; on the other hand, the present application adopts a solvent-free method to prepare the thermal control film, which has low energy consumption, low VOC, and is more environmentally friendly, thereby better adapting to space environment applications. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 Shown is the appearance of the thermal control film of the present application. DETAILED DESCRIPTION
[0020] The present application discloses a thermal control film and its preparation method and application. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It is particularly important to point out that all similar substitutions and modifications are obvious to those skilled in the art, and they are all deemed to be included in this application. The products, processes and applications described in this application have been described through preferred embodiments. Relevant personnel can obviously modify or appropriately change and combine the processes and applications described in this article without departing from the content, spirit and scope of this application to implement and apply the technology of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.
[0021] It should be noted that, in this article, if relational terms such as "first" and "second", "step 1" and "step 2", and "(1)" and "(2)" appear, they are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the sentence "comprise one..." do not exclude the presence of other identical elements in the process, method, article or equipment including the elements. At the same time, the embodiments in this application and the features in the embodiments may be combined with each other without conflict.
[0022] In the prior art, the current solution cast thermal control film usually mixes fluororesin, inorganic filler (silicon oxide, titanium dioxide, magnesium oxide), coupling agent, and organic solvent into a solution, then obtains a film by casting, and then the thermal control film is vacuum dried. However, on the one hand, the inorganic thermal control filler of this material system is not highly compatible with the fluororesin, which easily affects the molding stability and long-term stability; on the other hand, this material system uses organic solvents, which will produce VOC gas, which is not conducive to environmental protection and is not suitable for space environment.
[0023] In view of the above-mentioned defects of the prior art, in a first aspect of the present application, a thermal control film is provided, comprising a thermoplastic fluororesin, an inorganic thermal control filler and fumed silica.
[0024] The present application adds fumed silica as an anode protection filler, utilizing its high surface energy characteristics and hydrophilicity to react with the corrosive free fluoride ions formed during the high temperature process of the fluororesin during the granulation and film forming process, thereby protecting the thermal control filler from the influence of the free fluoride ions, inhibiting its discoloration, and maintaining high reflectivity.
[0025] In certain embodiments of the present application, the thermal control film comprises 100 parts of thermoplastic fluororesin, 50-80 parts of inorganic thermal control filler and 1-8 parts of fumed silica in parts by weight. In other embodiments of the present application, the thermal control film comprises 500g (100 parts) of thermoplastic fluororesin, 400g (80 parts) of inorganic thermal control filler and 10g (2 parts) of fumed silica. Alternatively, the thermal control film comprises 500g (100 parts) of thermoplastic fluororesin, 400g (80 parts) of inorganic thermal control filler and 20g (4 parts) of fumed silica.
[0026] In certain embodiments of the present application, the thermoplastic fluorine resin includes ethylene-tetrafluoroethylene copolymer or polyperfluoroethylene propylene. The present application uses ethylene-tetrafluoroethylene copolymer and polyperfluoroethylene propylene as binders, and the molding process is simple, no solvent is involved in film formation, it is more environmentally friendly, and has the advantages of high production efficiency. At the same time, ethylene-tetrafluoroethylene copolymer and polyperfluoroethylene propylene have good weather resistance and can improve the stability of the film.
[0027] In certain embodiments of the present application, the inorganic thermal control filler includes one or more of zinc titanate, calcium fluoride, sodium fluoride, and zirconium fluoride. Zinc titanate, calcium fluoride, sodium fluoride, and zirconium fluoride are white powders with high reflectivity, which can reduce the solar absorption ratio of the thermal control film. In other embodiments of the present application, the inorganic thermal control filler includes zinc titanate and one or more of calcium fluoride, sodium fluoride, and zirconium fluoride.
[0028] In certain embodiments of the present application, the particle size of the zinc titanate is preferably 500nm-2μm, and the particle size of calcium fluoride, sodium fluoride, and zirconium fluoride is preferably 800nm-5μm. Suitable particle size materials can be beneficial to the performance of the thermal control film. Zinc titanate reduces the absorptivity in the film and has a high emissivity to achieve the thermal control function, but zinc titanate is affected by free fluoride ions and will discolor, affecting the thermal control performance. The fumed silica added in this application protects it and improves the long-term stability of the thermal control film. Fumed silica has a high emissivity and can further improve the heat dissipation performance of the thermal control film. At the same time, calcium fluoride, sodium fluoride, and zirconium fluoride have good matching properties with fluororesins and are not easily affected by free fluoride ions generated during the aging process of fluororesins. In some other embodiments of the present application, the mass ratio of zinc titanate: fluoride is 3:1-6:1, and the mass of each fluoride is preferably equal.
[0029] In a second aspect of the present application, a method for preparing the thermal control film is provided, comprising:
[0030] The inorganic thermal control filler and the fumed silica are uniformly mixed to obtain a mixed filler;
[0031] The mixed filler is mixed with the thermoplastic fluororesin and then granulated to obtain a primary masterbatch;
[0032] The thermal control film is obtained by tape casting using the primary masterbatch as a raw material.
[0033] In certain embodiments of the present application, the melt flow rate of the thermoplastic fluororesin is 30-40 g / 10 min;
[0034] In certain embodiments of the present application, the extrusion pressure of the granulation is 6-10 MPa, and the granulation temperature is 280-320° C. In other embodiments of the present application, the particle size of the primary masterbatch is 2-3 mm.
[0035] In some embodiments of the present application, the temperature of the tape casting is 280-320° C., and the extrusion pressure is 10-15 MPa. In some other embodiments of the present application, the thickness of the film is 100-120 μm.
[0036] The above temperature affects the stability and dispersion uniformity of the resin. If the temperature is too high, the resin will decompose and discolor, affecting absorption; if the temperature is too low, the fluidity will decrease and the material cannot be evenly dispersed. Granulation and cast film molding at 280-320℃ can ensure that both aspects are maintained at a better level.
[0037] In certain embodiments of the present application, the preparation method comprises:
[0038] Add the inorganic thermal control filler and fumed silica into a horizontal mixer to obtain a uniformly mixed filler at a stirring rate of 30-40 rpm;
[0039] Add the mixed filler and thermoplastic fluororesin into a twin-screw mixer and perform extrusion granulation to obtain primary masterbatch. The extrusion pressure is 6-10MPa and the granulation temperature is 280-320℃.
[0040] The primary masterbatch is added into a single screw extruder for film extrusion casting, the extrusion temperature is 280-320°C, and the extrusion pressure is 10-15MPa.
[0041] In the third aspect of the present application, the thermal control film of the present application uses a highly stable fluoride inorganic thermal control filler of suitable particle size to replace the commonly used inorganic oxide thermal control fillers such as zinc oxide and titanium dioxide, which not only meets the high reflectivity characteristics, but also meets the matching requirements of the high-temperature molding process of fluororesins. At the same time, the zinc titanate thermal control filler is protected by high-specific surface area fumed silica to inhibit the reaction of free fluoride ions and thermal control fillers during the high-temperature molding process of fluororesins and inhibit discoloration; at the same time, the fluoride thermal control filler is not easily affected by the free fluoride ions generated during the aging process of fluororesins, and the long-term stability of the thermal control film is further improved in combination with fumed silica. Based on this, the present application provides the application of the thermal control film in the preparation of spacecraft.
[0042] In certain embodiments of the present application, the spacecraft includes one or more of an artificial satellite, a space station, a space shuttle, an aerospace plane, and a space probe.
[0043] In a fourth aspect of the present application, a spacecraft is provided, the surface and / or interior of which comprises the thermal control film described in the present application. The thermal control film can be applied locally or entirely, including but not limited to various optical instruments, laser instruments, communication equipment, substrate surfaces, etc. on the spacecraft.
[0044] In each group of comparative experiments provided in this application, unless otherwise specified, other experimental conditions, materials, etc. are kept consistent except for the differences indicated in each group, so as to provide comparability. The experimental materials and reagents used in the examples can be obtained from commercial channels unless otherwise specified.
[0045] The following is a further description of a thermal control film provided in the present application and its preparation method and application.
[0046] Embodiment 1:
[0047] 300 g of zinc titanate, 50 g of calcium fluoride, 50 g of zirconium fluoride and 10 g of fumed silica were stirred at 35 rpm for 30 min to obtain a mixed filler;
[0048] Granulate 410 g of mixed filler and 500 g of ethylene-tetrafluoroethylene copolymer at 300° C. and 8 MPa to obtain primary masterbatch with a particle size of 2-3 mm;
[0049] The primary masterbatch was cast and extruded at 300°C and 10MPa to form a film to obtain a thermal control film with a thickness of 100-120μm. Figure 1 .
[0050] Furthermore, according to GJB2502.2 "Test Methods for Spacecraft Thermal Control Coatings Part 2: Solar Absorption Ratio Test", the solar absorption ratio of the film was 0.15; according to GJB2502.3 "Test Methods for Spacecraft Thermal Control Coatings Part 3: Emissivity Test", the hemispherical emissivity of the film was 0.88. After 500 hours of xenon lamp aging, the solar absorption ratio of the film was 0.15, with no significant change.
[0051] Embodiment 2:
[0052] 300 g of zinc titanate, 50 g of calcium fluoride, 50 g of zirconium fluoride and 10 g of fumed silica were stirred at 35 rpm for 30 min to obtain a mixed filler;
[0053] Granulate 410g of mixed filler and 500g of polyperfluoroethylene propylene at 300°C and 8MPa to obtain primary masterbatch with a particle size of 2-3mm;
[0054] The primary masterbatch was cast and extruded into a film at 300° C. and 10 MPa to obtain a thermal control film with a thickness of 100-120 μm. The appearance of the film was consistent with that of Example 1.
[0055] According to GJB2502.2 "Test Methods for Thermal Control Coatings of Spacecraft Part 2: Solar Absorption Ratio Test", the solar absorption ratio of the film is 0.17; according to GJB2502.3 "Test Methods for Thermal Control Coatings of Spacecraft Part 3: Emissivity Test", the hemispherical emissivity of the film is 0.89. After 500 hours of xenon lamp aging, the solar absorption ratio of the film is 0.17, with no significant change.
[0056] Embodiment 3:
[0057] 300 g of zinc titanate, 50 g of calcium fluoride, 50 g of zirconium fluoride and 20 g of fumed silica were stirred at 35 rpm for 30 min to obtain a mixed filler;
[0058] Granulate 410 g of mixed filler and 500 g of ethylene-tetrafluoroethylene copolymer at 300° C. and 8 MPa to obtain primary masterbatch with a particle size of 2-3 mm;
[0059] The primary masterbatch was cast and extruded into a film at 300° C. and 10 MPa to obtain a thermal control film with a thickness of 100-120 μm. The appearance of the film was consistent with that of Example 1.
[0060] According to GJB2502.2 "Test Methods for Thermal Control Coatings of Spacecraft Part 2: Solar Absorption Ratio Test", the solar absorption ratio of the film is 0.15; according to GJB2502.3 "Test Methods for Thermal Control Coatings of Spacecraft Part 3: Emissivity Test", the hemispherical emissivity of the film is 0.90. After 500 hours of xenon lamp aging, the solar absorption ratio of the film is 0.15, with no significant change.
[0061] Comparative Example 1:
[0062] Compared with Example 1, Comparative Example 1 does not add fumed silica.
[0063] According to GJB2502.2 "Test Methods for Thermal Control Coatings of Spacecraft Part 2: Solar Absorption Ratio Test", the solar absorption ratio of the film is 0.25; according to GJB2502.3 "Test Methods for Thermal Control Coatings of Spacecraft Part 3: Emissivity Test", the hemispherical emissivity of the film is 0.84. After 500 hours of xenon lamp aging, the solar absorption ratio of the film is 0.28, which shows a significant increase.
[0064] Comparative Example 2:
[0065] 200 g of zinc oxide and 200 g of titanium oxide were stirred at 35 rpm for 30 min to obtain a mixed filler;
[0066] Granulate 400g of mixed filler and 500g of ethylene-tetrafluoroethylene copolymer at 300°C and 8MPa to obtain primary masterbatch with a particle size of 2-3mm;
[0067] The primary masterbatch is cast and extruded into a film at 300°C and 10MPa to obtain a thermal control film with a thickness of 100-120μm.
[0068] According to GJB2502.2 "Test Methods for Thermal Control Coatings on Spacecraft Part 2: Solar Absorption Ratio Test", the solar absorption ratio of the film was 0.29; according to GJB2502.3 "Test Methods for Thermal Control Coatings on Spacecraft Part 3: Emissivity Test", the hemispherical emissivity of the film was 0.86. After 500 hours of xenon lamp aging, the solar absorption ratio of the film was 0.31, showing a significant increase.
[0069] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.
Claims
1. A thermal control film, characterized in that: It includes thermoplastic fluororesin, inorganic thermal control filler and fumed silica.
2. The thermal control film according to claim 1, characterized in that: The invention comprises, by weight, 100 parts of thermoplastic fluororesin, 50-80 parts of inorganic thermal control filler and 1-8 parts of fumed silica.
3. The thermal control film according to claim 1 or 2, characterized in that: The thermoplastic fluorine resin includes ethylene-tetrafluoroethylene copolymer or poly(perfluoroethylene-propylene).
4. The thermal control film according to claim 1 or 2, characterized in that: The inorganic thermal control filler includes one or more of zinc titanate, calcium fluoride, sodium fluoride and zirconium fluoride.
5. The thermal control film according to claim 4, characterized in that: The inorganic thermal control filler includes zinc titanate, and one or more of calcium fluoride, sodium fluoride and zirconium fluoride.
6. The method for preparing the thermal control film according to claim 1, characterized in that: include: The inorganic thermal control filler and the fumed silica are uniformly mixed to obtain a mixed filler; The mixed filler is mixed with the thermoplastic fluororesin and then granulated to obtain a primary masterbatch; The thermal control film is obtained by tape casting using the primary masterbatch as a raw material.
7. The preparation method according to claim 6, characterized in that: The temperature of the tape casting is 280-320° C., and the extrusion pressure is 10-15 MPa.
8. Use of the thermal control film according to any one of claims 1 to 5 in the manufacture of spacecraft.
9. The use according to claim 7, characterized in that: The spacecraft includes one or more of an artificial satellite, a space station, a space shuttle, an aerospace plane, and a space probe.
10. A spacecraft, characterized in that: Its surface and / or interior comprises the thermal control film according to any one of claims 1 to 5.