Aluminized polyester film with high spatial environmental stability for spacecraft and continuous production method thereof

Abstract

This invention relates to the field of aerospace functional thin film materials technology, specifically to a high-space-environment-stability aluminized polyester film for spacecraft and its continuous production method. The film comprises a polyester substrate layer, a composite aluminum layer, and a fluorinated aluminum layer. The polyester substrate layer contains an ionic liquid, carbon nanotubes, and a polar polymer. The ionic liquid and carbon nanotubes form a three-dimensional conductive network, while the polar polymer forms a polymer alloy with the polyester and is selectively enriched on the surface. The composite aluminum layer contains cerium and lanthanum rare earth elements, and yttrium may be added optionally. The fluorinated aluminum layer is generated in situ by introducing CF4 gas after vapor deposition. During preparation, a linear evaporation source is used to vapor-deposit the composite aluminum layer, while a DC bias is applied and the substrate temperature is controlled. This film exhibits an adhesion grade of 5B, a surface sheet resistance of less than 2.5 Ω / □, a hardness greater than 2.0 GPa, and a reflectivity attenuation of less than 2.0% after ultraviolet irradiation, demonstrating excellent space-environment stability and antistatic properties.

Description

Technical Field

[0001] This invention relates to the field of aerospace functional thin film materials technology, specifically to a high space environment stability aluminized polyester film for spacecraft and its continuous production method. Background Technology

[0002] Metallized polyester film, due to its lightweight, high reflectivity, and good processability, has become a widely used reflective material in multilayer thermal insulation components for spacecraft. In the low Earth orbit environment, this material is exposed to extreme conditions such as atomic oxygen, ultraviolet radiation, high vacuum, and plasma for extended periods, and the stability of its thermal control performance directly affects the reliability of the spacecraft throughout its entire lifespan. However, as space missions develop towards longer lifespans and higher reliability, the problems exposed by traditional metallized polyester films in terms of space environment adaptability and process consistency are becoming increasingly prominent.

[0003] In his paper "Degradation of Space Polymers: A Case Study" (Utah State University, 2015, Paper 36), Peterson analyzed aluminized PET film samples returned from the International Space Station's MISSE-6 experiment. The analysis revealed that after 18 months of in-orbit exposure, the vacuum-deposited aluminum layer showed significant signs of atomic oxygen erosion. Simultaneously, the polymer matrix yellowed due to ultraviolet irradiation, significantly reducing the thermal control function of the reflector. The PET film used in this study was 7.6 μm thick, and the aluminized layer was 100 nm thick. The root cause of the degradation was the columnar, porous structure of the aluminum layer obtained by traditional vacuum evaporation processes. This abundant grain boundaries and insufficient density provided pathways for atomic oxygen erosion and also resulted in low hardness of the aluminum layer, making it susceptible to scratches from friction or micrometeoroid impacts during spacecraft assembly and in-orbit operation.

[0004] The aforementioned problems were further confirmed in more systematic space exposure experiments. de Groh et al., in their report "MISSE6 Stressed Polymers Experiment Atomic Oxygen Erosion Data" (NASA / TM-2013-217847, March 2013), clearly pointed out that the degree of atomic oxygen erosion of aluminized polymer films is closely related to the defect density on the film surface. A porous or pinhole-containing aluminum layer accelerates atomic oxygen penetration, leading to localized ablation and rapid attenuation of reflectivity. Furthermore, the interface matching problem between the polyester substrate and the aluminum layer is also significant. When aluminized polyester films operate in a space plasma environment, the accumulation of surface charge can trigger electrostatic discharge, causing localized ablation and pinhole formation in the aluminum layer, thus compromising the integrity of the thermal control layer. In terms of manufacturing processes, traditional single-point evaporation sources struggle to maintain uniform aluminum layer thickness under wide-width, high-speed winding conditions. This results in significant differences in thermal control performance across different areas of large-area thermal insulation components, posing challenges to the design and assembly of large spacecraft.

[0005] Therefore, there is an urgent need for a metallized polyester film for spacecraft with a dense aluminum layer, high adhesion, low surface sheet resistance and excellent stability in the space environment, as well as its production method. Summary of the Invention

[0006] This invention addresses the problems existing in the prior art by providing a high-space-environment-stability aluminized polyester film for spacecraft and its continuous production method. The aim is to obtain an aluminized film with a dense aluminum layer, high hardness, and high adhesion, thereby significantly improving its ability to resist on-orbit atomic oxygen erosion, ultraviolet radiation, and micrometeoroid impacts. At the same time, it enhances antistatic properties by reducing surface sheet resistance and achieves uniform coating under wide-area and high-speed conditions, thus meeting the application requirements of large spacecraft for long-life and high-reliability thermal control materials.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] The first aspect of this invention provides a metallized polyester film for spacecraft with high space environment stability, comprising: A polyester substrate layer comprising polyester and ionic liquid, carbon nanotubes and polar polymer dispersed therein; A composite aluminum layer is disposed on the surface of the polyester substrate layer, and the composite aluminum layer contains aluminum and rare earth elements. And an aluminum fluoride layer, disposed on the surface of the composite aluminum layer away from the polyester substrate layer.

[0009] Furthermore, the ionic liquid is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, the carbon nanotubes are multi-walled carbon nanotubes, the mass ratio of the ionic liquid to the carbon nanotubes is 2:1 to 3:1, and the content of carbon nanotubes accounts for 0.3% to 0.8% of the total mass of the polyester substrate layer.

[0010] Furthermore, the polar polymer is selected from at least one of polyamide, polycarbonate, and polyurethane, and the mass ratio of the polar polymer to the polyester is 5:95 to 30:70.

[0011] Furthermore, the rare earth elements in the composite aluminum layer include at least cerium and lanthanum, wherein the mass ratio of cerium to lanthanum is 1.5:1 to 2.5:1, and the total mass of cerium and lanthanum accounts for 0.5% to 1.0% of the total mass of the composite aluminum layer.

[0012] Furthermore, the composite aluminum layer also contains yttrium, with a mass ratio of yttrium to cerium of 1:4 to 1:3.

[0013] Furthermore, the thickness of the composite aluminum layer is 80–100 nm, and the thickness of the aluminum fluoride layer is 2–4 nm.

[0014] Furthermore, the aluminum fluoride layer is generated in situ by introducing fluorine-containing gas onto the surface of the composite aluminum layer.

[0015] The second aspect of this invention provides a method for preparing the aforementioned aluminized polyester film for spacecraft with high space environment stability, comprising the following steps: (1) Ionic liquid, carbon nanotubes and polar polymers are blended with polyester chips, and polyester film substrate is prepared by melt extrusion and biaxial stretching; (2) The polyester film substrate is placed in a vacuum coating chamber, and aluminum wire containing rare earth elements is used as the evaporation material. A composite aluminum layer is formed on one side of the film substrate by evaporation through a linear evaporation source. During evaporation, a DC bias voltage is applied to the cooling roller carrying the film, and the temperature of the film substrate is controlled. (3) After the vapor deposition is completed, a fluorine-containing gas is introduced into the vacuum coating chamber to generate an aluminum fluoride layer on the surface of the composite aluminum layer. Then the film is wound up under the protection of an inert gas to obtain the aluminized polyester film for spacecraft.

[0016] Furthermore, in step (2), the DC bias voltage is -50V to -200V, and the temperature of the thin film substrate is controlled between -10℃ and 10℃.

[0017] Furthermore, in step (3), the fluorine-containing gas is CF4, the flow rate is 80-150 sccm, and the in-situ reaction time is 1-3 minutes.

[0018] The aluminized polyester film of this invention imparts antistatic properties, high adhesion, resistance to atomic oxygen attack, and thermal stability to the material through a stepwise transition from the polyester substrate to the surface aluminum fluoride layer. Ionic liquids and carbon nanotubes are simultaneously introduced into the polyester substrate layer, forming a three-dimensional conductive network within the substrate. This significantly reduces the volume resistivity, thereby rapidly dissipating surface charges induced by the space plasma environment and preventing electrostatic discharge-induced ablation of the aluminum layer. Simultaneously, polar polymers such as polyamides, polycarbonates, or polyurethanes are dispersed within the substrate. These polymers form partially compatible alloy structures with the polyester matrix during melt extrusion and biaxial stretching. Due to surface energy differences, the polar polymers selectively accumulate on the film surface. The polar functional groups such as amide, carbonate, or urethane groups on their molecular chains chemically adsorb or Lewis acid-base coordinate with aluminum atoms during aluminum deposition, forming a stronger interfacial bond than traditional physical adsorption. This integrated internal addition method avoids the need for an additional primer coating process, and the enriched layer forms naturally during substrate molding, eliminating storage degradation issues.

[0019] The cerium and lanthanum rare earth elements introduced into the composite aluminum layer are oxidized in situ during vacuum evaporation, agglomerating at the grain boundaries of aluminum as nanoscale oxide particles. When atomic oxygen invades along the grain boundaries, these rare earth oxides preferentially react with atomic oxygen to form dense cerium oxide and lanthanum oxide, blocking grain boundary channels and inhibiting further oxidation of aluminum, thereby slowing down the decrease in aluminum layer reflectivity. The further added yttrium element, through synergistic effect with cerium, forms a more stable composite oxide at the grain boundaries, improving structural integrity under high temperature and irradiation conditions. Aluminum fluoride layer with a thickness of only 2-4 nanometers is generated in situ on the aluminum layer surface by introducing carbon tetrafluoride and utilizing residual plasma to excite the reaction. Aluminum fluoride has extremely high chemical inertness and hardly reacts under low Earth orbit atomic oxygen flux, acting as a physical barrier to prevent atomic oxygen from directly contacting the aluminum layer surface. This fluorinated layer is formed under low-temperature conditions, does not damage the polyester substrate, and its ultra-thin characteristics have negligible impact on solar spectral reflectivity.

[0020] During the fabrication process, a negative bias is applied to the cooling roller supporting the film, subjecting the growing aluminum layer to low-energy ion bombardment. This bombardment disrupts the continuous growth of columnar crystals, forcing the aluminum layer to form a denser microcrystalline structure, reducing grain boundary density and porosity, thereby decreasing the number of atomic oxygen diffusion channels. Simultaneously, the cooling roller controls the substrate temperature between -10°C and 10°C, inhibiting surface diffusion of aluminum atoms and further refining the grains, while preventing thermal shrinkage or deformation of the polyester substrate due to overheating. The synergistic effect of the bias and low temperature increases the hardness and reduces the sheet resistance of the aluminum layer, and provides a more uniform and dense reaction interface during subsequent fluorination. The strong adhesion provided by the polar polymer within the substrate, the grain boundary protection of the rare-earth aluminum layer, the surface passivation of the fluorinated aluminum layer, and the bias-based low-temperature densification process together constitute a multi-layered protection system, with each component working in concert. This systematic design allows the film to maintain low reflectivity decay even after exposure to ultraviolet irradiation and atomic oxygen, while maintaining a sheet resistance of less than two ohms per square meter, meeting the long-life thermal control and antistatic requirements of spacecraft.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. By introducing ionic liquids and carbon nanotubes into the polyester substrate to construct a three-dimensional conductive network, the sheet resistance of the film surface is significantly reduced, which can quickly dissipate the static charge induced by the space plasma environment and effectively avoid electrostatic discharge ablation damage to the aluminum layer.

[0022] 2. The polar polymer dispersed in the substrate is selectively enriched on the surface, and its polar functional groups form chemical bonds with aluminum atoms, achieving an adhesion level of 5B, which is far superior to traditional aluminum-plated films, ensuring the integrity of the multilayer structure during spacecraft launch and on-orbit thermal cycling.

[0023] 3. The cerium and lanthanum rare earth elements in the composite aluminum layer form nano-oxide particles at the grain boundaries. On the one hand, they pin the grain boundaries to increase the hardness of the aluminum layer, and on the other hand, they preferentially oxidize and block the atomic oxygen erosion channels, so that the reflectivity attenuation after ultraviolet irradiation is controlled within 2.0%.

[0024] 4. The aluminum fluoride passivation layer generated in situ on the surface of the aluminum layer has extremely high chemical inertness. As a physical barrier, it directly blocks the attack of atomic oxygen and ultraviolet radiation on the aluminum layer, forming an internal and external synergy with the grain boundary protection.

[0025] 5. The preparation process combines DC bias-assisted deposition with low-temperature control to form a dense microcrystalline structure in the aluminum layer, achieving a hardness of over 2.0 GPa, while avoiding thermal deformation of the polyester substrate.

[0026] 6. The preparation process of this invention can be implemented using existing roll-to-roll coating equipment without the need for additional equipment, and is highly compatible with existing production lines, making it easy to industrialize and promote. The comprehensive performance of this film meets the requirements of long-life thermal control and antistatic properties for spacecraft, and has broad application prospects in multilayer thermal insulation components for spacecraft such as low Earth orbit satellites and space stations. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the aluminized polyester film of the present invention. Wherein, 1-aluminum fluoride, 2-composite aluminum layer, 3-polyester substrate layer. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the raw materials used in the embodiments are all commercially available products.

[0029] The roll-to-roll vacuum coating equipment used in this embodiment of the invention is a commercially available conventional model. This equipment is equipped with an unwinding unit, a winding unit, a corona treatment device, a low-temperature plasma cleaning station, a linear evaporation source array, a coating cooling roller through which coolant can be introduced, and a DC bias power supply electrically connected to the cooling roller. This equipment is a standard configuration in existing industrial production and requires no additional modification or components.

[0030] Example 1 This embodiment provides a metallized polyester film for spacecraft with high stability in space environment, and its preparation method includes the following steps: (1) Preparation of polyester film substrate Polyester chips (PET, intrinsic viscosity 0.65 dL / g), ionic liquid, multi-walled carbon nanotubes, and a polar polymer were mixed in a specific ratio. The ionic liquid was 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, the multi-walled carbon nanotubes had an average diameter of 10 nm, and the polar polymer was polyamide 6 (PA6, relative viscosity 2.4). The mass ratios of the components were as follows: ionic liquid to multi-walled carbon nanotubes was 2.5:1, with multi-walled carbon nanotubes accounting for 0.5% of the total mass of the polyester substrate layer; the mass ratio of polar polymer to polyester chips was 10:90. The mixture was melt-blended in a twin-screw extruder, then melt-extruded, cast, and biaxially stretched (longitudinal stretch ratio 3.2 times, transverse stretch ratio 3.5 times) to obtain a polyester film substrate with a thickness of approximately 12 μm.

[0031] (2) Vacuum evaporation of composite aluminum layer The polyester film substrate obtained in step (1) is placed in a roll-to-roll vacuum coating machine, and the vacuum chamber is evacuated to a base vacuum level of 3×10⁻⁶. -3 Pa. Aluminum wire containing rare earth elements was used as the evaporation raw material. The mass ratio of cerium to lanthanum in the aluminum wire was 2:1, and the total mass of cerium and lanthanum accounted for 0.8% of the total mass of the aluminum wire. A composite aluminum layer was deposited on one side of the thin film substrate using a linear evaporation source. During the deposition process, a DC bias of -100 V was applied to the cooling roller supporting the thin film, and a coolant was simultaneously circulated inside the cooling roller to control the temperature of the thin film substrate at -5℃. The winding speed was 8 m / min, and the thickness of the composite aluminum layer after deposition was approximately 90 nm.

[0032] (3) In-situ formation of aluminum fluoride layer After the vapor deposition is completed, the vacuum chamber pressure is maintained at 1 Pa, and CF4 gas is introduced into the vacuum chamber at a flow rate of 100 sccm. The residual plasma in the vacuum chamber is used to excite the decomposition of CF4, so that the surface of the composite aluminum layer reacts with active fluorine. The reaction time is 2 minutes, and an aluminum fluoride layer with a thickness of about 3 nm is generated in situ.

[0033] (4) Collecting the roll The coated film is wound up under constant tension under nitrogen protection to obtain the aluminized polyester film for spacecraft.

[0034] A schematic diagram of the structure of the aluminized polyester film is shown below. Figure 1 As shown.

[0035] Example 2 This embodiment provides a metallized polyester film for spacecraft with high stability in space environment, and its preparation method includes the following steps: (1) Preparation of polyester film substrate Polyester chips (PET, intrinsic viscosity 0.65 dL / g), ionic liquid, multi-walled carbon nanotubes, and a polar polymer were mixed in a specific ratio. The ionic liquid was 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, the multi-walled carbon nanotubes had an average diameter of 10 nm, and the polar polymer was polycarbonate (PC, molecular weight 26000). The mass ratios of the components were as follows: ionic liquid to multi-walled carbon nanotubes was 2.2:1, with multi-walled carbon nanotubes accounting for 0.6% of the total mass of the polyester substrate layer; the mass ratio of polar polymer to polyester chips was 15:85. The mixture was melt-blended in a twin-screw extruder, then melt-extruded, cast, and biaxially stretched (longitudinal stretch ratio 3.3 times, transverse stretch ratio 3.6 times) to obtain a polyester film substrate with a thickness of approximately 12 μm.

[0036] (2) Vacuum evaporation of composite aluminum layer The polyester film substrate obtained in step (1) is placed in a roll-to-roll vacuum coating machine, and the vacuum chamber is evacuated to a base vacuum level of 3×10⁻⁶. -3Pa. Aluminum wire containing rare earth elements was used as the evaporation raw material. The mass ratio of cerium to lanthanum in the aluminum wire was 1.8:1, and the total mass of cerium and lanthanum accounted for 0.7% of the total mass of the aluminum wire. A composite aluminum layer was deposited on one side of the thin film substrate using a linear evaporation source. During the deposition process, a DC bias of -80 V was applied to the cooling roller supporting the thin film, and a coolant was simultaneously circulated inside the cooling roller to control the temperature of the thin film substrate at -2℃. The winding speed was 8.5 m / min, and the thickness of the composite aluminum layer after deposition was approximately 85 nm.

[0037] (3) In-situ formation of aluminum fluoride layer After the vapor deposition is completed, the vacuum chamber pressure is maintained at 1.2 Pa, and CF4 gas is introduced into the vacuum chamber at a flow rate of 90 sccm. The residual plasma in the vacuum chamber is used to excite the decomposition of CF4, so that the surface of the composite aluminum layer reacts with active fluorine. The reaction time is 2.5 minutes, and an aluminum fluoride layer with a thickness of about 3.5 nm is generated in situ.

[0038] (4) Collecting the roll The coated film is wound up under constant tension under nitrogen protection to obtain the aluminized polyester film for spacecraft.

[0039] Example 3 This embodiment provides an aluminized polyester film for spacecraft with high stability in the space environment, and its preparation method includes the following steps.

[0040] (1) Preparation of polyester film substrate Polyester chips (PET, intrinsic viscosity 0.65 dL / g), ionic liquid, multi-walled carbon nanotubes, and a polar polymer were mixed in a specific ratio. The ionic liquid was 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, the multi-walled carbon nanotubes had an average diameter of 10 nm, and the polar polymer was thermoplastic polyurethane (TPU, hardness 82A). The mass ratios of the components were as follows: ionic liquid to multi-walled carbon nanotubes was 2.8:1, with multi-walled carbon nanotubes accounting for 0.4% of the total mass of the polyester substrate layer; the mass ratio of polar polymer to polyester chips was 25:75. The mixture was melt-blended in a twin-screw extruder, then melt-extruded, cast, and biaxially stretched (longitudinal stretch ratio 3.1 times, transverse stretch ratio 3.4 times) to obtain a polyester film substrate with a thickness of approximately 12 μm.

[0041] (2) Vacuum evaporation of composite aluminum layer The polyester film substrate obtained in step (1) is placed in a roll-to-roll vacuum coating machine, and the vacuum chamber is evacuated to a base vacuum level of 3×10⁻⁶. -3Pa. Aluminum wire containing rare earth elements was used as the evaporation raw material. The mass ratio of cerium to lanthanum in the aluminum wire was 2.5:1. Yttrium was also added to the aluminum wire, with a mass ratio of yttrium to cerium of 1:3.5. The total mass of cerium, lanthanum, and yttrium accounted for 1.0% of the total mass of the aluminum wire. A composite aluminum layer was deposited on one side of the thin film substrate using a linear evaporation source. During the evaporation process, a DC bias of -150 V was applied to the cooling roller supporting the thin film, and coolant was simultaneously circulated inside the cooling roller to control the temperature of the thin film substrate at 5°C. The winding speed was 7.5 m / min, and the thickness of the composite aluminum layer after evaporation was approximately 95 nm.

[0042] (3) In-situ formation of aluminum fluoride layer After the vapor deposition is completed, the vacuum chamber pressure is maintained at 1.8 Pa, and CF4 gas is introduced into the vacuum chamber at a flow rate of 130 sccm. The residual plasma in the vacuum chamber is used to excite the decomposition of CF4, so that the surface of the composite aluminum layer reacts with active fluorine. The reaction time is 1.5 minutes, and an aluminum fluoride layer with a thickness of about 3 nm is generated in situ.

[0043] (4) Collecting the roll The coated film is wound up under constant tension under nitrogen protection to obtain the aluminized polyester film for spacecraft.

[0044] Comparative Example 1 The only difference between this comparative example and Example 1 is that step (3) is omitted, that is, no CF4 gas is introduced after the composite aluminum layer is deposited, and no aluminum fluoride layer is generated. After the deposition is completed, the film is directly wound up under nitrogen protection.

[0045] Comparative Example 2 The only difference between this comparative example and Example 1 is that no polar polymer is added in step (1). The polyester film substrate consists only of polyester chips, ionic liquid, and multi-walled carbon nanotubes, with the following mass ratio: ionic liquid to multi-walled carbon nanotubes in a mass ratio of 2.5:1, and multi-walled carbon nanotubes accounting for 0.5% of the total mass of the substrate. The remaining steps are the same as in Example 1.

[0046] Comparative Example 3 This comparative example provides an aluminized polyester film for spacecraft, the preparation method of which includes the following steps.

[0047] (1) Preparation of polyester film substrate Polyester chips (PET, intrinsic viscosity 0.65 dL / g), ionic liquid, and multi-walled carbon nanotubes were mixed in a specific ratio. The ionic liquid was 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, and the multi-walled carbon nanotubes had an average diameter of 10 nm. The mass ratio of the components was 2.5:1, with the multi-walled carbon nanotubes accounting for 0.5% of the total mass of the polyester substrate layer. No polar polymers were added. The mixture was melt-blended in a twin-screw extruder, then melt-extruded, cast, and biaxially stretched to obtain a polyester film substrate with a thickness of approximately 12 μm.

[0048] (2) Coating with a polar polymer layer Polyamide 6 (PA6, relative viscosity 2.4) was dissolved in formic acid to prepare a 5% (w / w) solution. The solution was coated onto the surface of the polyester film substrate obtained in step (1) using a gravure roller coating method. The solvent was removed by hot air drying at 60°C, forming a polar polymer layer with a thickness of about 1 μm on the substrate surface.

[0049] (3) Vacuum evaporation of composite aluminum layer The film obtained in step (2) is placed in a roll-to-roll vacuum coating machine, and the vacuum chamber is evacuated to a base vacuum of 3×10⁻⁶. -3 Pa. Aluminum wire containing rare earth elements was used as the evaporation raw material. The mass ratio of cerium to lanthanum in the aluminum wire was 2:1, and the total mass of cerium and lanthanum accounted for 0.8% of the total mass of the aluminum wire. A composite aluminum layer was deposited on the side of the thin film coated with a polar polymer layer using a linear evaporation source. During the evaporation process, a DC bias of -100 V was applied to the cooling roller supporting the thin film, and a coolant was simultaneously circulated inside the cooling roller to control the temperature of the thin film substrate at -5℃. The winding speed was 8 m / min, and the thickness of the composite aluminum layer after evaporation was approximately 90 nm.

[0050] (4) In-situ formation of aluminum fluoride layer After the vapor deposition is completed, the vacuum chamber pressure is maintained at 1 Pa, and CF4 gas is introduced into the vacuum chamber at a flow rate of 100 sccm. The residual plasma in the vacuum chamber is used to excite the decomposition of CF4, so that the surface of the composite aluminum layer reacts with active fluorine. The reaction time is 2 minutes, and an aluminum fluoride layer with a thickness of about 3 nm is generated in situ.

[0051] (5) Collect the roll The coated film is wound up under constant tension under nitrogen protection to obtain the aluminized polyester film for spacecraft.

[0052] Comparative Example 4 The only difference between this comparative example and Example 1 is that pure aluminum wire is used as the evaporation raw material in step (2). The remaining steps are the same as in Example 1.

[0053] Performance testing The following performance tests were performed on the aluminized polyester films of Examples 1-3 and Comparative Examples 1-4.

[0054] (1) Adhesion The coating adhesion was tested according to GB / T 9286-2021 "Cross-cut test for paints and varnishes". 100 1 mm × 1 mm squares were cut into the surface of the aluminum fluoride layer of the film using a cross-cutting tool. The tool cut through the aluminum fluoride layer and the aluminum layer to the substrate surface. 3M 610 tape was applied and then quickly peeled off. The extent of aluminum layer detachment from the substrate surface was observed. According to the standard rating: 5B indicates smooth cut edges with no detachment, and 0B indicates the most severe detachment.

[0055] (2) Surface sheet resistance After the composite aluminum layer is deposited by vapor deposition and before the aluminum fluoride layer is formed, the surface sheet resistance of the aluminum layer is tested by DC four-probe method. Five different positions are measured for each sample and the average value is taken.

[0056] (3) Hardness Nanoindentation was used to perform indentation tests on the surface of the aluminum fluoride layer of the thin film. The micro Vickers hardness value was calculated according to GB / T 4340.1-2024 "Metallic materials - Vickers hardness test - Part 1: Test method". The test load was 10 mN and the holding time was 10 s. Five points were tested for each sample and the average value was taken.

[0057] (4) Reflectance attenuation after ultraviolet irradiation Referring to GB / T 16422.3-2022 "Laboratory Light Source Exposure Test Methods for Plastics - Part 3: Fluorescent Ultraviolet Lamps", a UVA-340 lamp tube was used to conduct ultraviolet irradiation equivalent to 1000 ESH (solar hours) at 60℃. The solar spectral reflectance of the film in the 250-2500 nm band before and after irradiation was measured using a spectrophotometer, and the reflectance attenuation rate was calculated.

[0058] The test results are shown in Table 1.

[0059] Table 1 Performance Test Results

[0060] The above test results show that the adhesion of all embodiments of the present invention reaches the highest level of 5B, the surface sheet resistance is controlled between 1.8-2.3 Ω / □, the hardness is between 2.1-2.4 GPa, and the reflectance decay after 1000 hours of UV irradiation does not exceed 2.0%, indicating that the present invention exhibits excellent performance in terms of adhesion, conductivity, mechanical properties, and spatial environment stability. Comparative Example 1, without the formation of an aluminum fluoride layer, showed a significant increase in reflectance decay after UV irradiation, indicating that the aluminum fluoride layer, as a surface chemical inert barrier, can effectively block UV-induced oxidation corrosion. Comparative Example 2, without the addition of polar polymers, showed a significant decrease in adhesion, indicating that the chemical bonding between functional groups formed by the polar polymer on the surface and aluminum atoms is key to obtaining high adhesion. Comparative Example 3, where the polar polymer was coated separately on the substrate surface rather than blended within the substrate, showed a decrease in adhesion and added an extra step, indicating that the uniform enrichment of the polar polymer on the substrate surface after overall blending forms a more durable and uniform interfacial bond than separate coating. Comparative Example 4, which uses pure aluminum wire vapor deposition without adding rare earth elements, showed a significant deterioration in both hardness and reflectivity after ultraviolet irradiation. This demonstrates that the oxide particles formed by rare earth elements at the grain boundaries of the aluminum layer not only strengthen the aluminum layer but also delay the overall corrosion of the aluminum layer through a preferential oxidation mechanism.

[0061] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A space environment stable aluminized polyester film for spacecraft, characterized by, include: A polyester substrate layer comprising polyester and ionic liquid, carbon nanotubes and polar polymer dispersed therein; A composite aluminum layer is disposed on the surface of the polyester substrate layer, and the composite aluminum layer contains aluminum and rare earth elements. And an aluminum fluoride layer, disposed on the surface of the composite aluminum layer away from the polyester substrate layer.

2. The aluminized polyester film for spacecraft use having high spatial environmental stability according to claim 1, characterized by: The ionic liquid is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, the carbon nanotubes are multi-walled carbon nanotubes, the mass ratio of the ionic liquid to the carbon nanotubes is 2:1 to 3:1, and the content of carbon nanotubes accounts for 0.3% to 0.8% of the total mass of the polyester substrate layer.

3. The aluminized Mylar® film of claim 1 having high spatial environmental stability for spacecraft applications, wherein: The polar polymer is selected from at least one of polyamide, polycarbonate, and polyurethane, and the mass ratio of the polar polymer to the polyester is 5:95 to 30:

70.

4. The aluminized Mylar® film of claim 1 having high spatial environmental stability for spacecraft applications, wherein: The rare earth elements in the composite aluminum layer include at least cerium and lanthanum, wherein the mass ratio of cerium to lanthanum is 1.5:1 to 2.5:1, and the total mass of cerium and lanthanum accounts for 0.5% to 1.0% of the total mass of the composite aluminum layer.

5. The aluminized Mylar® film of claim 1 having high spatial environmental stability for spacecraft applications, wherein: The composite aluminum layer also contains yttrium, with a mass ratio of yttrium to cerium of 1:4 to 1:

3.

6. The aluminized Mylar® film of claim 1 having high spatial environmental stability for spacecraft applications, wherein: The thickness of the composite aluminum layer is 80–100 nm, and the thickness of the aluminum fluoride layer is 2–4 nm.

7. The aluminized Mylar® film of claim 1 having high spatial environmental stability for spacecraft applications, wherein: The aluminum fluoride layer is generated in situ by introducing fluorine-containing gas into the surface of the composite aluminum layer.

8. A method for preparing a metallized polyester film for spacecraft with high space environment stability as described in any one of claims 1-7, comprising the following steps: (1) Ionic liquid, carbon nanotubes and polar polymers are blended with polyester chips, and polyester film substrate is prepared by melt extrusion and biaxial stretching; (2) The polyester film substrate is placed in a vacuum coating chamber, and aluminum wire containing rare earth elements is used as the evaporation material. A composite aluminum layer is formed on one side of the film substrate by evaporation through a linear evaporation source. During evaporation, a DC bias voltage is applied to the cooling roller carrying the film, and the temperature of the film substrate is controlled. (3) After the vapor deposition is completed, a fluorine-containing gas is introduced into the vacuum coating chamber to generate an aluminum fluoride layer on the surface of the composite aluminum layer. Then the film is wound up under the protection of an inert gas to obtain the aluminized polyester film for spacecraft.

9. The method of claim 8, wherein: In step (2), the DC bias voltage is -50V to -200V, and the temperature of the thin film substrate is controlled between -10℃ and 10℃.

10. The method of claim 8, wherein: In step (3), the fluorine-containing gas is CF4, the flow rate is 80-150 sccm, and the in-situ reaction time is 1-3 minutes.

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