Flexible ultrathin thin film with adjustable infrared emissivity and preparation method thereof

Abstract

The invention discloses a flexible ultrathin thin film with adjustable infrared emissivity and a preparation method thereof, and belongs to the field of preparation of intelligent thermal control materials. The invention aims to solve the problems that the existing thermal control device is difficult to prepare and mostly adopts a rigid substrate, and the characteristic structure and the thickness are required for realizing the large-amplitude thermal control regulation performance. The flexible ultrathin film with the adjustable infrared emissivity is prepared from an infrared high-transparency composite film and a high-infrared reflection substrate from top to bottom in sequence. The preparation method comprises the following steps: 1, adding rod-like functional phase particles into a solvent for ultrasonic dispersion, and then adding a surfactant; and 2, spraying, plastic packaging and hot pressing. The invention is used for the flexible ultrathin thin film with adjustable infrared emissivity and the preparation method thereof.

Description

Technical Field

[0001] The invention belongs to the field of preparation of intelligent thermal control materials. Background Art

[0002] Spacecraft in orbit face the harsh space environment, subjected to both high-temperature solar radiation and deep-cold space radiation. These drastic temperature fluctuations pose significant challenges to thermal control systems. With the increasing variability of external spacecraft heat flux, the rapidly increasing power density of internal equipment, and the increasing demands for temperature control precision, thermal control technologies based on radiative heat exchange surfaces face even higher demands. Traditional thermal control coatings, due to their fixed thermal radiation properties, cannot adjust their properties according to internal and external heat flux variations, making adaptive temperature control of equipment difficult. Variable emissivity intelligent thermal control coatings dynamically change their infrared radiation properties according to operating temperature, achieving temperature control effects that maintain heat at low temperatures and dissipate heat at high temperatures. This significantly improves thermal control efficiency and has become a key component of spacecraft thermal control systems. VO2, a typical thermochromic material, exhibits a semiconductor state (high infrared transmittance) at low temperatures and a metallic state (high infrared reflectance) at high temperatures. Coating it on the surface of a protected object effectively dissipates heat at high temperatures, reducing temperatures and reducing cooling energy consumption; while effectively retaining heat at low temperatures, maintaining temperatures and reducing heating energy consumption, thereby achieving energy savings. However, to apply VO2 in practice, its inherent defects need to be overcome: the material is not the most thermodynamically stable phase in air, is easily oxidized in the actual environment, and is affected by factors such as high and low temperature shock, ultraviolet aging, etc., resulting in performance degradation. Therefore, the radiation resistance and antioxidant capabilities of VO2 intelligent thermal control films need to be improved urgently. In addition to the protection of VO2 intrinsic materials, there are also difficulties in the preparation of thermal control devices. Existing thermal control devices are mostly rigid substrates, and in order to achieve a large range of thermal control performance, characteristic structures and thickness issues are required. Summary of the Invention

[0003] The present invention aims to solve the problem that existing thermal control devices are difficult to prepare and most of them have rigid substrates, and that characteristic structures and thicknesses are required to achieve large-scale thermal control performance. It further provides a flexible ultra-thin infrared emissivity adjustable film and its preparation method.

[0004] A flexible ultra-thin infrared emissivity adjustable film, which is prepared from top to bottom in sequence by an infrared functional composite film and a high infrared reflective substrate;

[0005] The infrared functional composite film is prepared from two infrared highly transparent films and a plurality of rod-shaped functional phase particles, wherein the rod-shaped functional phase particles are evenly distributed between the two infrared highly transparent films; the length of the rod-shaped functional phase particles is 1 μm to 2 μm, and the diameter is 80 nm to 240 nm; the rod-shaped functional phase particles are VO2(M) rod-shaped particles, element-doped VO2(M) rod-shaped particles or shell-coated VO2(M) rod-shaped particles; the mass ratio of the rod-shaped functional phase particles to the two infrared highly transparent films is (0.1 to 0.3):1.

[0006] A preparation method of a flexible ultrathin infrared emissivity adjustable film, which is carried out according to the following steps:

[0007] I. Under the condition that the power is 40W~150W, the rod-shaped functional phase particles are added to the solvent and ultrasonic dispersion is carried out for 10min~150min, then the surfactant polyvinylpyrrolidone-K30 is added, and stirring dispersion is carried out under the condition that the rotating speed is 400r / min~1500r / min for 10min~150min, to obtain a spraying solution;

[0008] II. The spraying solution is uniformly sprayed on an infrared high-transparency film, and normal temperature is placed for 5min~60min, then another infrared high-transparency film and a high-infrared reflection base are sequentially covered on the surface, and plastic encapsulation hot pressing is carried out under the condition that the temperature is 100℃~200℃ for 30s~1min, to obtain the flexible ultrathin infrared emissivity adjustable film.

[0009] The beneficial effects of the present application are:

[0010] The present application selects a VO2 rod-shaped structure which can play a role in dynamic thermal management and thermal camouflage as a functional phase, compared with the commonly used spherical and linear, the rod-shaped structure is in an intermediate state, and has the functions of realizing two states; a flexible ultrathin film preparation method which can be applied to intrinsic VO2 and modified VO2 to play effective thermal control characteristics is selected, which has more advantages in infrared thermal regulation, and the lapping of the rod-shaped structure before and after modification provides higher fault tolerance for this preparation method, specifically:

[0011] (1) The film preparation method adopted by the present application is hydrothermal method, spraying method and plastic encapsulation hot pressing, compared with methods such as magnetron sputtering and pulse laser deposition which depend on high-vacuum equipment, the cost is high and it is difficult to produce in large area, and the present application has the advantages of simplicity, low cost and large area production;

[0012] (2) The VO2 with rod-shaped structure adopted by the present application is dispersed on the infrared transparent base, so that the fault tolerance of the film is high, and specific size and specific structure are not needed to realize infrared emissivity regulation;

[0013] (3) The present application is a flexible base with small thickness, and can be bent at will, this characteristic makes it applied in emerging fields such as curved intelligent window and wearable thermal management device, and greatly expands the application scenarios of VO2 material.

[0014] (4) The present application realizes that the infrared emissivity of the film can change automatically with the ambient temperature (low emissivity at low temperature, high emissivity at high temperature) by designing the thermally induced emissivity material and the film system, thereby meeting the needs of intelligent thermal control. Excellent infrared thermal regulation performance can be obtained with extremely low mass ratio and ultra-thinness. The preparation method of plastic packaging and hot pressing makes the film have good environmental stability while maintaining flexibility. The method has short process, low energy consumption, high thermal regulation capacity, loose preparation conditions, improves the anti-aging performance and prolongs the service life. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 Figure 1 is a structural schematic diagram of the flexible ultra-thin infrared emissivity adjustable film of the present application, 1 is an infrared high transparent film, 2 is a rod-shaped functional phase particle, and 3 is a high infrared reflection substrate;

[0016] Figure 2 Figure 4 is a scanning electron microscope image of the flexible ultra-thin infrared emissivity adjustable film prepared in step two of Example 1 after the sprayed solution is uniformly sprayed on the infrared high transparent film and placed at room temperature;

[0017] Figure 3 Figure 5 is an infrared reflection spectrum of the flexible ultra-thin infrared emissivity adjustable film prepared in step two of Example 1;

[0018] Figure 4 Figure 6 is an infrared reflection spectrum of the flexible ultra-thin infrared emissivity adjustable film prepared in step two of Example 3;

[0019] Figure 5 Figure 7 is an optical picture of the flexible ultra-thin infrared emissivity adjustable film prepared in Example 1. DETAILED DESCRIPTION

[0020] Specific implementation one, in combination Figure 1 Specific description: the flexible ultra-thin infrared emissivity adjustable film of the embodiment is prepared from an infrared functional composite film and a high infrared reflection substrate from top to bottom;

[0021] The infrared functional composite film is prepared from two infrared high transparent films and a plurality of rod-shaped functional phase particles, and the rod-shaped functional phase particles are uniformly distributed between the two infrared high transparent films; the length of the rod-shaped functional phase particles is 1-2 μm, and the diameter is 80-240 nm; the rod-shaped functional phase particles are VO2(M) rod-shaped particles, element-doped VO2(M) rod-shaped particles or shell-coated VO2(M) rod-shaped particles; the mass ratio of the rod-shaped functional phase particles to the two infrared high transparent films is (0.1-0.3):1.

[0022] The embodiment has the following beneficial effects:

[0023] The VO2 rod structure selected in the embodiment can play a role in dynamic thermal management and thermal camouflage. Compared with the commonly used spherical and linear structures, the rod structure is in an intermediate state and has the functions of both states. A flexible and ultra-thin film preparation method suitable for both intrinsic VO2 and modified VO2 to play effective thermal control characteristics is selected, which has an advantage in infrared thermal regulation. The lapping of the rod structure before and after modification provides a higher fault tolerance for the preparation method, specifically:

[0024] (1) The film preparation method adopted in the embodiment is hydrothermal method, spraying method and plastic sealing hot pressing, which has the advantages of simplicity, low cost and large-area production compared with methods such as magnetron sputtering and pulse laser deposition which rely on high-vacuum equipment and have high cost and are difficult to produce in large areas.

[0025] (2) The dispersion of the VO2 rod structure on the infrared transparent substrate in the embodiment makes the film have a high fault tolerance, and does not require specific size and specific structure to achieve infrared emissivity regulation.

[0026] (3) The flexible substrate in the embodiment has a small thickness and can be bent at will. This feature enables it to be applied in emerging fields such as curved intelligent windows and wearable thermal management devices, greatly expanding the application scenarios of VO2 materials.

[0027] (4) The embodiment designs a thermally induced variable emissivity material and a film system to achieve a self-changing infrared emissivity of the film with the environment temperature (low emissivity at low temperature and high emissivity at high temperature), thereby meeting the needs of intelligent thermal control. The method can achieve excellent infrared thermal regulation performance with extremely low mass ratio and ultra-thin thickness. The plastic sealing hot pressing preparation method enables the film to maintain good environmental stability while maintaining flexibility. The method has a short process, low energy consumption, high thermal regulation capacity, and loose preparation conditions, which is easy to mass-produce, improves the anti-aging performance, and prolongs the service life.

[0028] Specific implementation method two: The difference between the embodiment and the specific implementation method one is that the core of the shell-coated VO2(M) rod-shaped particle is a VO2(M) rod-shaped core or an element-doped VO2(M) rod-shaped core, and the shell is a material with high infrared transparency and anti-aging performance. The element-doped VO2(M) rod-shaped particle and the element-doped VO2(M) rod-shaped core are both W-VO2(M) rod-shaped particles, and W accounts for 0.5% to 2.5% of the total atomic number of W and V. The others are the same as the specific implementation method one.

[0029] Specific implementation method three: The difference between the embodiment and the specific implementation method one or two is that the material with high infrared transparency and anti-aging performance is calcium fluoride, hafnium oxide or zinc sulfide. The others are the same as the specific implementation method one or two.

[0030] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the shell-coated VO2(M) rod-shaped particles are prepared according to the following steps:

[0031] ① Ultrasonic dispersion of the core in deionized water for 10 min to 150 min at a power of 40 W to 150 W, and then adding a surfactant at room temperature and a stirring speed of 400 r / min to 1500 r / min to obtain a precursor solution;

[0032] The core is a VO2(M) rod-shaped core or an element-doped VO2(M) rod-shaped core;

[0033] The mass ratio of the core to the volume of deionized water is 1 g: (10-20) mL; the mass ratio of the core to the surfactant is (32-128):1; the surfactant is polyvinylpyrrolidone-K30, sodium lauryl sulfate or lecithin;

[0034] ② Add the shell reaction material A to deionized water and stir and disperse for 4 h to 6 h at room temperature and a stirring speed of 600 r / min to 800 r / min to obtain a shell precursor A solution / suspension;

[0035] The mass ratio of the shell reaction material A to the volume of deionized water is 1 g: (32-128) mL; the shell reaction material A is calcium chloride, hafnium tetrachloride or zinc sulfate;

[0036] ③ Add the shell reaction material B to deionized water and stir and disperse for 4 h to 6 h at room temperature and a stirring speed of 400 r / min to 1500 r / min to obtain a shell precursor B solution / suspension;

[0037] The mass ratio of the shell reaction material B to deionized water is 1g: (4-12)mL; the shell reaction material B is NaOH, ammonium sulfide or concentrated hydrochloric acid with a mass percentage of 36%-38%;

[0038] ④ Slowly add the shell precursor B solution / suspension to the shell precursor A solution / suspension at a dropping speed of 0.5 g / min to 10 g / min to obtain a mixed solution C;

[0039] The mass ratio of the shell reaction material B in the shell precursor B solution / suspension to the shell reaction material A in step ② is 1:(1-5);

[0040] ⑤Mix and disperse the precursor solution and the mixed solution C at room temperature and a stirring speed of 400 r / min to 1500 r / min for 3 h to 24 h to obtain a mixture;

[0041] The mass ratio of the core in the precursor solution to the shell layer reaction material A in step ② is 1:(0.5 to 4);

[0042] ⑥Hydrothermally react the mixture at a temperature of 100 ℃ to 160 ℃ for 6 h to 64 h, and then perform centrifugal washing, drying, and grinding after the hydrothermal reaction to obtain the shell-coated VO2(M) rod-shaped particles. The other aspects are the same as those in Embodiments One to Three.

[0043] Embodiment Five: The embodiment is different from Embodiments One to Four in that the infrared high-transparency film is a Karton resin, a polyamide resin, a phenolic resin, or a vinyl resin. The other aspects are the same as those in Embodiments One to Five.

[0044] Embodiment Six: The embodiment is different from Embodiments One to Five in that the high-infrared-reflection substrate is a copper sheet, an aluminum sheet, a flexible tin foil, or ITO. The other aspects are the same as those in Embodiments One to Five.

[0045] Embodiment Seven: A preparation method of a flexible ultrathin infrared emissivity adjustable film is performed in the following steps:

[0046] I. Under the condition of a power of 40 W to 150 W, the rod-shaped functional phase particles are ultrasonically dispersed in a solvent for 10 min to 150 min, and then a surfactant polyvinylpyrrolidone-K30 is added and stirred and dispersed at a rotating speed of 400 r / min to 1500 r / min for 10 min to 150 min to obtain a spraying solution.

[0047] II. The spraying solution is uniformly sprayed on the infrared high-transparency film, and then placed at room temperature for 5 min to 60 min, and then another infrared high-transparency film and a high-infrared-reflection substrate are sequentially covered on the surface, and then plastic encapsulation hot pressing is performed at a temperature of 100 ℃ to 200 ℃ for 30 s to 1 min to obtain the flexible ultrathin infrared emissivity adjustable film.

[0048] Embodiment Eight: The embodiment is different from Embodiment Seven in that the mass of the rod-shaped functional phase particles to the volume of the solvent in step I is 1 g:(100 to 200) mL; and the mass ratio of the rod-shaped functional phase particles to the surfactant in step I is 1:(0.005 to 0.01). The other aspects are the same as those in Embodiment Seven.

[0049] Specific embodiment nine: the difference between this embodiment and one of specific embodiments seven or eight is that the solvent in step one is ethanol, deionized water or acetone; the surfactant in step one is polyvinylpyrrolidone-K30, polyvinylpyrrolidone-K60, sodium dodecyl sulfate or lecithin. The rest is the same as specific embodiments seven or eight.

[0050] Specific embodiment ten: the difference between this embodiment and one of specific embodiments seven to nine is that the thickness of the infrared high-transparency film in step two is 10 μm~100 μm; the thickness of the high-infrared-reflection substrate in step two is 50 nm~5 μm; the thickness of the flexible ultrathin infrared emissivity-adjustable film in step two is 5 μm~30 μm. The rest is the same as specific embodiments seven to nine.

[0051] The beneficial effects of the present application are verified by the following examples:

[0052] Example one:

[0053] A flexible ultrathin infrared emissivity-adjustable film, which is prepared from an infrared functional composite film and a high-infrared-reflection substrate in order from top to bottom;

[0054] The infrared functional composite film is prepared from two infrared high-transparency films and a plurality of rod-shaped functional phase particles, which are uniformly distributed between the two infrared high-transparency films; the length of the rod-shaped functional phase particles is 1 μm~2 μm, and the diameter is 80 nm~100 nm; the rod-shaped functional phase particles are VO2(M) rod-shaped particles; the mass ratio of the rod-shaped functional phase particles to the two infrared high-transparency films is 0.1:1.

[0055] The VO2(M) rod-shaped particles are prepared by the following steps: under the conditions of room temperature and a stirring speed of 600 r / min, V2O5 and oxalic acid dihydrate are stirred for 8 h to obtain a blue vanadium precursor solution; under the condition of a temperature of 240 ℃, the blue vanadium precursor solution is hydrothermally treated for 1 h to obtain black precipitate; after being washed by centrifugation with deionized water and ethanol for 5 times, the black precipitate is placed under the condition of a temperature of 60 ℃ and dried for 8 h, and then ground to obtain VO2(B) powder; under the conditions of an argon flow rate of 200 sccm and a temperature of 500 ℃, the VO2(B) powder is annealed for 30 min and cooled to room temperature to obtain VO2(M) rod-shaped particles; the mass ratio of V2O5 to oxalic acid dihydrate is 1:3.

[0056] The infrared high-transparency film is polyethylene.

[0057] The high-infrared-reflection substrate is a flexible tin foil.

[0058] A preparation method of a flexible ultrathin infrared emissivity adjustable film, which is prepared according to the following steps:

[0059] I. Under the condition of 80W power, the rod-shaped functional phase particles are added into ethanol and ultrasonically dispersed for 30min, then polyvinylpyrrolidone-K30 is added, and stirring and dispersion are carried out at a rotating speed of 600r / min for 120min to obtain a spraying solution;

[0060] II. The spraying solution is uniformly sprayed on an infrared high-transparency film, and placed at room temperature for 30min, then another infrared high-transparency film and a high-infrared reflection substrate are sequentially covered on the surface, and plastic encapsulation hot pressing is carried out at a temperature of 180℃ for 30s to obtain the flexible ultrathin infrared emissivity adjustable film.

[0061] The mass and volume ratio of the rod-shaped functional phase particles to ethanol in step I is 1g:100mL; and the mass ratio of the rod-shaped functional phase particles to polyvinylpyrrolidone-K30 in step I is 1:0.005.

[0062] The size of the infrared high-transparency film in step II is 8cm×8cm×25μm.

[0063] The size of the high-infrared reflection substrate in step II is 8cm×8cm×1μm.

[0064] After the plastic encapsulation hot pressing in step II of the embodiment, the thickness of the film is further reduced, and the thickness of the obtained flexible ultrathin infrared emissivity adjustable film is 6μm.

[0065] Example 2:

[0066] A flexible ultrathin infrared emissivity adjustable film, which is prepared from top to bottom by an infrared functional composite film and a high-infrared reflection substrate;

[0067] The infrared functional composite film is prepared from two infrared high-transparency films and a plurality of rod-shaped functional phase particles, and the rod-shaped functional phase particles are uniformly distributed between the two infrared high-transparency films; the length of the rod-shaped functional phase particles is 1μm~2μm, and the diameter is 90nm~120nm; the rod-shaped functional phase particles are VO2(M) rod-shaped particles coated with a shell layer; and the mass ratio of the rod-shaped particles to the two infrared high-transparency films is 0.1:1.

[0068] In the VO2(M) particles coated with a shell layer, the core is a VO2(M) rod-shaped core, and the shell layer is hafnium oxide.

[0069] The VO2(M) rod-shaped particles coated with a shell layer are prepared according to the following steps:

[0070] ①Under the condition of 80W, the core was ultrasonically dispersed in deionized water for 30min, then polyvinylpyrrolidone-K30 was added under the condition of room temperature and stirring speed of 600r / min to obtain a precursor solution;

[0071] The core is VO2(M) rod-shaped core; the mass and volume ratio of the core to deionized water is 1g:10mL; the mass ratio of the core to polyvinylpyrrolidone-K30 is 32:1;

[0072] The VO2(M) rod-shaped core is prepared by the following steps: V2O5 and oxalic acid dihydrate are stirred for 8h under the condition of room temperature and stirring speed of 600r / min to obtain a blue vanadium precursor solution; the blue vanadium precursor solution is hydrothermally treated for 3h under the condition of temperature of 240℃ to obtain black precipitate; the black precipitate is washed by centrifugation with deionized water and ethanol for 5 times, and then is placed under the condition of temperature of 60℃ for drying for 12h, and then is ground to obtain VO2(B) powder; the VO2(B) powder is annealed for 120min under the condition of argon flow rate of 200sccm and temperature of 500℃, and then is cooled to room temperature to obtain VO2(M) rod-shaped core; the mass ratio of V2O5 to oxalic acid dihydrate is 1:2;

[0073] ②Hafnium oxychloride suspension is obtained by adding hafnium tetrachloride into deionized water under the condition of room temperature and stirring speed of 600r / min for 4h;

[0074] The mass and volume ratio of hafnium tetrachloride to deionized water is 1g:32mL;

[0075] ③NaOH solution is obtained by adding NaOH solid into deionized water under the condition of room temperature and stirring speed of 400r / min for 4h;

[0076] The mass and volume ratio of NaOH solid to deionized water is 1g:10mL;

[0077] ④The NaOH solution is slowly added into the hafnium oxychloride suspension at a dropping speed of 3g / min to obtain a mixed solution;

[0078] The mass ratio of NaOH in the NaOH solution to hafnium tetrachloride in step ② is 1:2;

[0079] ⑤The precursor solution and the mixed solution are mixed and dispersed for 10h under the condition of room temperature and stirring speed of 700r / min to obtain a mixture;

[0080] The mass ratio of the core in the precursor solution to hafnium tetrachloride in step ② is 1:1;

[0081] ⑥Under the condition that the temperature is 140℃, the mixture is hydrothermally reacted for 12h, after hydrothermal reaction, the mixture is washed by centrifugation with deionized water and ethanol for 5 times, then under the condition that the temperature is 60℃, the mixture is dried for 8h, and finally the mixture is ground, thereby the VO2(M) rod-shaped particles coated with shell are obtained.

[0082] The infrared high-transparency film is polyethylene.

[0083] The high-infrared-reflection substrate is flexible tin foil.

[0084] A preparation method of a flexible ultrathin infrared emissivity adjustable film, which is carried out according to the following steps:

[0085] I. Under the condition that the power is 100W, the rod-shaped functional phase particles are added into ethanol for ultrasonic dispersion for 30min, then polyvinylpyrrolidone-K30 is added, and under the condition that the rotating speed is 600r / min, the mixture is stirred and dispersed for 120min, thereby a spraying solution is obtained;

[0086] II. The spraying solution is uniformly sprayed on the infrared high-transparency film, and then the film is placed at room temperature for 30min, then another infrared high-transparency film and a high-infrared-reflection substrate are sequentially covered on the surface of the film, and under the condition that the temperature is 200℃, the film is plastic-sealed and hot-pressed for 1min, thereby the flexible ultrathin infrared emissivity adjustable film is obtained.

[0087] In step I, the mass of the rod-shaped functional phase particles to the volume of ethanol is 1g:100mL; in step I, the mass ratio of the rod-shaped functional phase particles to polyvinylpyrrolidone-K30 is 1:0.05.

[0088] In step II, the size of the infrared high-transparency film is 8cm×8cm×25μm.

[0089] In step II, the size of the high-infrared-reflection substrate is 8cm×8cm×1μm.

[0090] After the plastic-sealing and hot-pressing in step II of the embodiment, the thickness of the film is further reduced, and the thickness of the obtained flexible ultrathin infrared emissivity adjustable film is 8μm.

[0091] Example III:

[0092] A flexible ultrathin infrared emissivity adjustable film, which is prepared from an infrared functional composite film and a high-infrared-reflection substrate from top to bottom;

[0093] The infrared functional composite film is prepared from two infrared high-transparency films and a plurality of rod-shaped functional phase particles, and the rod-shaped functional phase particles are uniformly distributed between the two infrared high-transparency films; the length of the rod-shaped functional phase particles is 1-2 μm, and the diameter is 80-100 nm; the rod-shaped functional phase particles are element-doped VO2(M) rod-shaped particles; and the mass ratio of the rod-shaped functional phase particles to the two infrared high-transparency films is 0.1:1.

[0094] The element-doped VO2(M) rod-shaped particles are W-VO2(M) rod-shaped particles, and W accounts for 0.5% of the total atomic number of W and V.

[0095] The element-doped VO2(M) rod-shaped particles are prepared by the following steps: under the conditions of room temperature and a stirring speed of 800 r / min, V2O5 and oxalic acid dihydrate are stirred for 8 h to obtain a blue vanadium precursor solution; under the conditions of room temperature, tungstic acid is added to the blue vanadium precursor solution; under the conditions of room temperature and a stirring speed of 600 r / min, the solution is stirred for 3 h, and then the solution is hydrothermally treated at a temperature of 240℃ for 6 h to obtain black precipitate; after the black precipitate is washed by centrifugation with deionized water and ethanol for 5 times, the black precipitate is dried at a temperature of 60℃ for 8 h, and then ground to obtain W-VO2(B) powder; under the conditions of an argon flow rate of 200 sccm and a temperature of 600℃, the W-VO2(B) powder is annealed for 60 min, and then cooled to room temperature to obtain the element-doped VO2(M) rod-shaped particles; and the mass ratio of V2O5 to oxalic acid dihydrate is 1:2.

[0096] The infrared high-transparency film is polyethylene.

[0097] The high-infrared-reflection substrate is ITO.

[0098] A flexible ultrathin infrared emissivity-adjustable film and a preparation method thereof, which are prepared by the following steps:

[0099] I. Under the condition of a power of 80 W, the rod-shaped functional phase particles are added into ethanol and ultrasonically dispersed for 60 min, and then polyvinylpyrrolidone-K30 is added, and the mixture is stirred and dispersed at a rotating speed of 800 r / min for 60 min to obtain a spraying solution;

[0100] II. The spraying solution is uniformly sprayed on the infrared high-transparency film, and then placed at room temperature for 30 min, and then the surface is sequentially covered with another infrared high-transparency film and a high-infrared-reflection substrate, and then plastic encapsulation hot-pressed at a temperature of 200℃ for 1 min to obtain the flexible ultrathin infrared emissivity-adjustable film.

[0101] The mass ratio of the rod-shaped functional phase particles described in step 1 to the volume of ethanol is 1 g:150 mL; the mass ratio of the rod-shaped functional phase particles described in step 1 to polyvinylpyrrolidone-K30 is 1:0.01.

[0102] The size of the infrared highly transparent film described in step 2 is 8 cm×8 cm×25 μm.

[0103] The size of the high infrared reflective substrate in step 2 is 8 cm×8 cm×1 μm.

[0104] In step 2 of this embodiment, the thickness of the film is further reduced after the plastic sealing and hot pressing, and the thickness of the obtained flexible ultra-thin infrared emissivity adjustable film is 10 μm.

[0105] Example 4:

[0106] A flexible ultra-thin infrared emissivity adjustable film, which is prepared from top to bottom in sequence by an infrared functional composite film and a high infrared reflective substrate;

[0107] The infrared functional composite film is prepared from two infrared highly transparent films and a plurality of rod-shaped functional phase particles, and the rod-shaped functional phase particles are evenly distributed between the two infrared highly transparent films; the length of the rod-shaped functional phase particles is 1 μm~2 μm, and the diameter is 90 nm~120 nm; the rod-shaped functional phase particles are shell-coated VO2(M) rod-shaped particles; the mass ratio of the rod-shaped functional phase particles to the two infrared highly transparent films is 0.1:1.

[0108] The core of the shell-coated VO2(M) rod-shaped particles is an element-doped VO2(M) rod-shaped core, and the shell is hafnium oxide; the element-doped VO2(M) rod-shaped core is a W-VO2(M) rod-shaped particle, and W accounts for 0.5% of the total number of W and V atoms.

[0109] The shell-coated VO2(M) rod-shaped particles are prepared according to the following steps:

[0110] ① Ultrasonic dispersion of the core in deionized water at a power of 80 W for 30 min, followed by addition of polyvinylpyrrolidone-K30 at room temperature and a stirring speed of 600 r / min to obtain a precursor solution;

[0111] The core is an element-doped VO2(M) rod-shaped core; the mass ratio of the core to deionized water is 1g:20mL; the mass ratio of the core to polyvinylpyrrolidone-K30 is 1:0.1;

[0112] The element-doped VO2(M) rod-shaped core is specifically prepared according to the following steps: V2O5 and oxalic acid dihydrate are stirred for 8 hours at room temperature and a stirring speed of 800 r / min to obtain a blue vanadium precursor solution; tungstic acid is added to the blue vanadium precursor solution at room temperature, and stirred for 3 hours at room temperature and a stirring speed of 800 r / min; then, the solution is hydrothermaled at a temperature of 240°C for 6 hours to obtain a black precipitate; the black precipitate is centrifugally washed 5 times with deionized water and ethanol, and then dried at a temperature of 60°C for 8 hours. After grinding, W-VO2(B) powder is obtained; the W-VO2(B) powder is annealed for 60 minutes at an argon gas flow rate of 200 sccm and a temperature of 600°C, and then cooled to room temperature to obtain the element-doped VO2(M) rod-shaped core; the mass ratio of V2O5 to oxalic acid dihydrate is 1:2.

[0113] ② Add hafnium tetrachloride to deionized water at room temperature and a stirring speed of 600 r / min, and stir and disperse for 4 hours to obtain a hafnium oxychloride suspension;

[0114] The mass ratio of hafnium tetrachloride to deionized water is 1 g:32 mL;

[0115] ③ Under the conditions of room temperature and stirring speed of 600 r / min, add NaOH solid into deionized water and stir and disperse for 4 hours to obtain NaOH solution;

[0116] The mass ratio of the NaOH solid to the volume of deionized water is 1 g:4 mL;

[0117] ④ Slowly add the NaOH solution to the hafnium oxychloride suspension at a dropping rate of 3 g / min to obtain a mixed solution;

[0118] The mass ratio of NaOH in the NaOH solution to hafnium tetrachloride in step ② is 1:3;

[0119] ⑤ Mixing and dispersing the precursor solution and the mixed solution at room temperature and a stirring speed of 700 r / min for 8 hours to obtain a mixture;

[0120] The mass ratio of the core in the precursor solution to the hafnium tetrachloride in step ② is 2:1;

[0121] ⑥ The mixture was hydrothermally reacted at 140°C for 24 hours, washed five times by centrifugation with deionized water and ethanol, and then dried at 60°C for 8 hours. Finally, the mixture was ground to obtain shell-coated VO2(M) rod-shaped particles.

[0122] The infrared highly transparent film is made of polyethylene.

[0123] The high infrared reflective substrate is a flexible tin foil.

[0124] A flexible ultrathin infrared emissivity adjustable film and a preparation method thereof, which is prepared by the following steps:

[0125] I. Under the condition of 80W power, the rod-shaped functional phase particles are added into ethanol and ultrasonically dispersed for 60min, then polyvinylpyrrolidone-K30 is added, and stirring and dispersion are carried out at a rotating speed of 800r / min for 60min to obtain a spraying solution;

[0126] II. The spraying solution is uniformly sprayed on an infrared high-transparency film, and placed at room temperature for 30min, then another infrared high-transparency film and a high infrared reflective substrate are sequentially covered on the surface, and plastic encapsulation hot pressing is carried out at a temperature of 200℃ for 1min to obtain a flexible ultrathin infrared emissivity adjustable film.

[0127] The mass and volume ratio of the rod-shaped functional phase particles to ethanol in step I is 1g:100mL; and the mass ratio of the rod-shaped functional phase particles to polyvinylpyrrolidone-K30 in step I is 1:0.01.

[0128] The size of the infrared high-transparency film in step II is 8cm×8cm×25μm.

[0129] The size of the high infrared reflective substrate in step II is 8cm×8cm×1μm.

[0130] After the plastic encapsulation hot pressing in step II of the embodiment, the thickness of the film is further reduced, and the thickness of the obtained flexible ultrathin infrared emissivity adjustable film is 8μm.

[0131] Figure 2 The scanning electron microscope image of the infrared high-transparency film after the spraying solution is uniformly sprayed thereon and placed at room temperature in step II of the embodiment; as shown in the figure, the rod-shaped functional phase particles are distributed on the polyethylene film in step I of the embodiment, and the rod-shaped functional phase particles are dispersed on the polyethylene in a lap joint state.

[0132] Figure 3 The infrared reflectance spectrum of the flexible ultrathin infrared emissivity adjustable film prepared in step II of the embodiment; as shown in the figure, the flexible ultrathin infrared emissivity adjustable film prepared in step I of the embodiment has a low-temperature emissivity of 0.26 at 8μm~14μm waveband at 0℃, a high-temperature emissivity of 0.77 at 70℃, and an emissivity change value of 0.51 from 0℃ to 70℃.

[0133] Figure 4The infrared reflection spectrum of the flexible ultrathin infrared emissivity adjustable film prepared in Example Three Step Two; from the figure, the flexible ultrathin infrared emissivity adjustable film prepared in Example Three has a low temperature emissivity of 0.27 at 0℃ and a high temperature emissivity of 0.65 at 70℃ in the 8μm~14μm wave band. The emissivity change value is 0.38 from 0℃ to 70℃.

[0134] The flexible ultrathin infrared emissivity adjustable film prepared in Example Two has a low temperature emissivity of 0.29 at 0℃ and a high temperature emissivity of 0.78 at 70℃ in the 8μm~14μm wave band. The emissivity change value is 0.49 from 0℃ to 70℃.

[0135] The flexible ultrathin infrared emissivity adjustable film prepared in Example Four has a low temperature emissivity of 0.30 at 0℃ and a high temperature emissivity of 0.69 at 70℃ in the 8μm~14μm wave band. The emissivity change value is 0.39 from 0℃ to 70℃.

[0136] Figure 5 The optical picture of the flexible ultrathin infrared emissivity adjustable film prepared in Example One. From the figure, the prepared thermally induced variable emissivity film maintains the flexibility of the polyethylene film.

Claims

1. A flexible ultra-thin infrared emissivity adjustable film, characterized in that It is made up of infrared functional composite film and high infrared reflective substrate from top to bottom; The infrared functional composite film is prepared from two infrared highly transparent films and a plurality of rod-shaped functional phase particles, wherein the rod-shaped functional phase particles are evenly distributed between the two infrared highly transparent films; the length of the rod-shaped functional phase particles is 1 μm to 2 μm, and the diameter is 80 nm to 240 nm; the rod-shaped functional phase particles are VO2(M) rod-shaped particles, element-doped VO2(M) rod-shaped particles or shell-coated VO2(M) rod-shaped particles; the mass ratio of the rod-shaped functional phase particles to the two infrared highly transparent films is (0.1 to 0.3):

1.

2. The flexible ultra-thin infrared emissivity adjustable film according to claim 1, characterized in that The core of the shell-coated VO2(M) rod-shaped particles is a VO2(M) rod-shaped core or an element-doped VO2(M) rod-shaped core, and the shell is a material with high infrared transmittance and anti-aging properties; the element-doped VO2(M) rod-shaped particles and the element-doped VO2(M) rod-shaped core are both W-VO2(M) rod-shaped particles, and W accounts for 0.5% to 2.5% of the total number of W and V atoms.

3. The flexible ultra-thin infrared emissivity adjustable film according to claim 2, characterized in that The material with high infrared transmittance and anti-aging performance is calcium fluoride, hafnium oxide or zinc sulfide.

4. The flexible ultra-thin infrared emissivity adjustable film according to claim 3, characterized in that The shell-coated VO2(M) rod-shaped particles are prepared according to the following steps: ① Ultrasonic dispersion of the core in deionized water for 10 min to 150 min at a power of 40 W to 150 W, and then adding a surfactant at room temperature and a stirring speed of 400 r / min to 1500 r / min to obtain a precursor solution; The core is a VO2(M) rod-shaped core or an element-doped VO2(M) rod-shaped core; The mass ratio of the core to the volume of deionized water is 1 g: (10-20) mL; the mass ratio of the core to the surfactant is (32-128):1; the surfactant is polyvinylpyrrolidone-K30, sodium lauryl sulfate or lecithin; ② Add the shell reaction material A to deionized water and stir and disperse for 4 h to 6 h at room temperature and a stirring speed of 600 r / min to 800 r / min to obtain a shell precursor A solution / suspension; The mass ratio of the shell reaction material A to the volume of deionized water is 1 g: (32-128) mL; the shell reaction material A is calcium chloride, hafnium tetrachloride or zinc sulfate; ③ Add the shell reaction material B to deionized water and stir and disperse for 4 h to 6 h at room temperature and a stirring speed of 400 r / min to 1500 r / min to obtain a shell precursor B solution / suspension; The mass ratio of the shell reaction material B to deionized water is 1g: (4-12)mL; the shell reaction material B is NaOH, ammonium sulfide or concentrated hydrochloric acid with a mass percentage of 36%-38%; ④ Slowly add the shell precursor B solution / suspension to the shell precursor A solution / suspension at a dropping speed of 0.5 g / min to 10 g / min to obtain a mixed solution C; The mass ratio of the shell reaction material B in the shell precursor B solution / suspension to the shell reaction material A in step ② is 1:(1-5); ⑤ Mix and disperse the precursor solution and mixed solution C at room temperature and a stirring speed of 400 r / min to 1500 r / min for 3 h to 24 h to obtain a mixture; The mass ratio of the core in the precursor solution to the shell reaction material A in step ② is 1:(0.5-4); ⑥ The mixture is hydrothermally reacted at a temperature of 100°C to 160°C for 6h to 64h. After hydrothermal reaction, the mixture is centrifugally washed, dried and ground to obtain shell-coated VO2(M) rod-shaped particles.

5. The flexible ultra-thin infrared emissivity adjustable film according to claim 1, characterized in that The infrared high-transparency film is made of Karton resin, polyamide resin, phenolic resin or vinyl resin.

6. The flexible ultra-thin infrared emissivity adjustable film according to claim 1, characterized in that The high infrared reflective substrate is a copper sheet, an aluminum sheet, a flexible tin foil or ITO.

7. The method for preparing a flexible ultra-thin infrared emissivity adjustable film according to claim 1, characterized in that It is carried out in the following steps:

1. Add the rod-shaped functional phase particles to the solvent and ultrasonically disperse them for 10 to 150 minutes at a power of 40W to 150W. Then add the surfactant polyvinylpyrrolidone-K30 and stir and disperse them for 10 to 150 minutes at a speed of 400 to 1500 r / min to obtain a spray solution.

2. Spray the spray solution evenly on the infrared high-transparency film, leave it at room temperature for 5 minutes to 60 minutes, then cover the surface with another infrared high-transparency film and a high infrared reflective substrate in turn, and plastic seal and hot press for 30 seconds to 1 minute at a temperature of 100℃ to 200℃ to obtain a flexible ultra-thin infrared emissivity adjustable film.

8. The method for preparing a flexible ultra-thin infrared emissivity adjustable film according to claim 7, characterized in that The mass ratio of the rod-shaped functional phase particles described in step 1 to the volume of the solvent is 1 g: (100-200) mL; the mass ratio of the rod-shaped functional phase particles described in step 1 to the surfactant is 1: (0.005-0.01).

9. The method for preparing a flexible ultra-thin infrared emissivity adjustable film according to claim 7, characterized in that The solvent described in step 1 is ethanol, deionized water or acetone; the surfactant described in step 1 is polyvinylpyrrolidone-K30, polyvinylpyrrolidone-K60, sodium lauryl sulfate or lecithin.

10. The method for preparing a flexible ultra-thin infrared emissivity adjustable film according to claim 7, characterized in that The thickness of the infrared highly transparent film described in step 2 is 10 μm~100 μm; the thickness of the high infrared reflective substrate described in step 2 is 50 nm~5 μm; the thickness of the flexible ultra-thin infrared emissivity adjustable film described in step 2 is 5 μm~30 μm.

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