A black electro-controlled light valve film based on nano-sic particles and a preparation method thereof

Abstract

The application discloses a preparation method of a black electrically controlled light valve film based on nano SiC particles, and comprises the following steps: taking silica powder, graphite powder and NaCl-KCl with a mass ratio of 1:(2-5):(4-8) as raw materials to prepare rod-like SiC, wherein the molar ratio of NaCl to KCl is 1:(0.5-2); using a dopamine hydrochloride solution to modify the rod-like SiC to prepare black rod-like SiC@ dopamine powder; using oleic acid to modify the rod-like SiC@ dopamine to prepare modified black nano rod-like SiC powder; dispersing the modified black nano rod-like SiC powder in a dispersing agent, adding a stabilizer to prepare a black dispersion liquid; providing silica gel, uniformly mixing the black dispersion liquid with the silica gel to prepare a coating material; coating the coating material on the ITO surface of one ITO-PET conductive film and performing drying treatment to form a coating layer, oppositely arranging the ITO surface of the other ITO-PET conductive film to the coating layer and performing pressing treatment to prepare a black electrically controlled light valve film. The application can be electrically controlled to switch between colorless transparent and black transparent states, and meets the sunshade requirements of a vehicle regulation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrically controlled light valve materials, and particularly relates to a preparation method of a black electrically controlled light valve film based on nano-SiC particles and a black electrically controlled light valve film based on nano-SiC particles prepared by the preparation method. BACKGROUND

[0002] The electrically controlled light valve film is made of transparent conductive film material and belongs to a novel transparent conductive film material that can be controlled by electro-optics. When the voltage is different, the color of the film body of the electrically controlled light valve film changes, so that the light transmittance changes to achieve the technology of controlling the light transmittance. The existing light valve film mainly includes the following four categories:

[0003] (1) PDLC film (polymer dispersed liquid crystal light control film): for example, the patent CN116253916A discloses that the high and low voltage induces the specific angle deflection of liquid crystal molecules to realize the control of light transmittance, so as to achieve the conversion of "colorless transparent" to "milk white shadow". The material is cheap, and the conversion speed is fast (usually <1s). However, the light shielding state is milk white, and the light transmittance is serious under the sunlight, the white light is dazzling, the angle is poor and unavoidable, and the haze is large. Moreover, the liquid crystal and the encapsulation material (acrylic polyurethane resin) are organic matters, and the weather resistance is poor, so they cannot resist the sunlight and high temperature for a long time, and therefore cannot be used as a sandwich layer on the building outer wall and the automobile outer window glass.

[0004] (2) Dyeing PDLC material: for example, the patent CN112379546A discloses that the dyeing PDLC material is obtained by adding anthraquinone / azo two-phase dye to the PDLC film material, so that the dye and the liquid crystal molecules form "two-phase domain cooperation". When the voltage changes, the film material can be converted between "light color transparent" and "blue shielding" / "blue-black shielding", the conversion speed is fast, the color is deeper than the PDLC film, and the sunshade effect is better. However, the material is expensive, the color of the shielding state is blue, which will make the light more bright and dazzling after light transmittance, and more seriously, the weather resistance of anthraquinone and azo pigment is poorer due to the high activity of the two, so the film layer will start to fade after several months under the sunlight or high temperature environment, and finally lose effectiveness, and the service life is shorter than that of the PDLC.

[0005] (Three) EC: take patent CN108363255A as an example, the patent relates to a kind of electrochromic film material and the electrochromic film device prepared by it, the patent utilizes oxidation-reduction principle, mass production product uses WO3 Or polystyrene class material as anode, nickel oxide or prussian blue base as cathode, with lithium ion doped gel electrolyte as core material, if need color has black phase, then always again doped in electrolyte purple violet class color-changing material after mixing and coated between double-layer ITO-PET And solidified into film. By controlling the direction and size of direct current before double-layer ITO-PET, make anode and cathode change color simultaneously to change light transmittance. EC compared with PDLC film, there is no angle problem and haze problem, the color of the film is uniform after changing color;Sunshade effect can reach the standard of dyed PDLC, working voltage is low (generally lower than 5V) and is direct current, more energy-saving. The disadvantage is that the oxidation-reduction reaction time is too long, and it takes nearly two minutes to change color for a large film material of a car window;Color always contains blue, and the light is dazzling after transmittance. Because of repeated "charging", lithium ions are easily embedded and the cycle life is extremely short, only thousands of cycle times. As the electrolyte is a very active organic matter, it is extremely unstable under sunlight and high temperature, and it is extremely sensitive to water vapor and oxygen. Unless multiple layers of thickening are used to gradually protect the aircraft window, otherwise it will fail within a year.

[0006] (Four) SPD (suspended particle device) light valve film: mainly a kind of nano electric control film material prepared by American cutting-edge research company, take patent CN104885001A as an example, the patent uses nitrocellulose as dispersant by dissolving in ester solvent, then reacts to generate nano NaI / KI / I3 system. Under alternating current field, nano particles will produce rotation phenomenon with the frequency of alternating current due to their own dipole moment, so as to realize the controllable switching of "colorless transparent"-"blue transparent" to control light transmittance. The color-changing speed is fast, comparable to PDLC film;Color is transparent, like blue sunglasses, shading without shading. However, because the nano particles are generated in the three-dimensional nitrocellulose grid that has been dispersed, the rotation resistance is large, so the working voltage is very high, requiring 110V-150V alternating current. Because the nitrocellulose of dispersion grid structure and iodine compounds are very sensitive to light and heat, the film material cannot be exposed to sunlight or high temperature (temperature > 55℃) for a long time. If it is applied to building exterior wall or car outer window, the service life will be less than half a year;Color is single, and the blue color in the color is relatively heavy, so the sunlight is dazzling when transmittance. SUMMARY

[0007] The application aims to provide a preparation method of a black electrically controlled light valve film based on nano-SiC particles and the black electrically controlled light valve film prepared by the preparation method.

[0008] To achieve the above-mentioned purpose, the application adopts the following technical solutions.

[0009] In one aspect, the application provides a preparation method of a black electrically controlled light valve film based on nano-SiC particles, which comprises the following steps.

[0010] S10, using silica powder, graphite powder and NaCl-KCl with a mass ratio of 1: (2-5): (4-8) as raw materials, rod-shaped SiC is prepared, wherein the molar ratio of NaCl to KCl is 1: (0.5-2) ;

[0011] S20, the rod-shaped SiC is pretreated, then modified by using a dopamine hydrochloride solution, and aftertreated to obtain black rod-shaped SiC@ dopamine powder;

[0012] S30, the rod-shaped SiC@ dopamine is modified by using oleic acid to obtain modified black nanorod-shaped SiC powder;

[0013] S40, the modified black nanorod-shaped SiC powder prepared in step S30 is dispersed in a dispersant and a stabilizer is added to obtain a black dispersion liquid;

[0014] S50, silica gel is provided, the black dispersion liquid is mixed with the silica gel and uniformly dispersed to obtain a coating material;

[0015] S60, two ITO-PET conductive films are provided, the coating material is coated on the ITO surface of one of the ITO-PET conductive films and dried to form a coating layer, then the ITO surface of the other ITO-PET conductive film is opposite to the coating layer and pressed to obtain a black electrically controlled light valve film.

[0016] The reaction of the silica powder and the graphite powder in the NaCl-KCl is as follows:

[0017] SiO2+ 3C = SiC + 2CO

[0018] The eutectic temperature of NaCl-KCl is 650 DEG C, which can reduce the reaction conditions of the silica powder and the graphite powder, induce the directional growth of SiC along the 111 plane into a rod-shaped structure, and reduce the possibility of oxidation of SiC caused by air contact as an inert medium.

[0019] The present application uses nano-SiC particles to replace nano-NaI / KI / I3 system, SiC as inorganic matter, which is extremely insensitive to light and heat, and can resist sun and high and low temperature for a long time; the process of "using dopamine hydrochloride to modify the prepared nano-powder" is adopted to replace the old process of "first forming a dispersion system and then generating nano-powder", so that the rotational resistance of nano-particles under the dipole moment is extremely low, thereby reducing the working voltage from above 110V to about 36V; the black color formed after sintering the nano-SiC modified by dopamine hydrochloride has natural color without other colors, and will not be bright and dazzling when light passes through, and the appearance is like black sunglasses, and the sunshade effect felt by the human eye is natural and comfortable, which is the only scheme that can realize natural black in the field of electro-optical control materials; the uniform dispersion formed by the adsorption and dispersion of alkane end in the solvent and the electrostatic repulsion between them is used to replace the three-dimensional grid dispersion of nitrocellulose, and since the stability of oleic acid is much higher than that of nitrocellulose, the sensitivity of the black electro-controlled light valve film prepared by the present application to light and heat will be greatly reduced, thereby being more stable and more weather-resistant.

[0020] As a further scheme of the preparation method of the black electro-controlled light valve film based on nano-SiC particles, step S10 specifically comprises the following steps:

[0021] S10a, grinding silica powder, graphite powder and NaCl-KCl uniformly;

[0022] S10b, heating to 1000-1500℃ under Ar atmosphere and stirring, the heating rate is 5-10℃ / min;

[0023] S10c, centrifugal washing and vacuum drying at 70-85℃, to prepare rod-like SiC;

[0024] Among them, the particle size of the silica powder is <100nm.

[0025] As a further scheme of the preparation method of the black electro-controlled light valve film based on nano-SiC particles, step S20 specifically comprises the following steps:

[0026] S20a, adding rod-like SiC into acid solution with a temperature of 50-70℃ for ultrasonic washing, and drying the obtained precipitate to obtain dry SiC powder;

[0027] S20b, adding dopamine hydrochloride into Tris-HCl buffer solution to prepare a dopamine hydrochloride solution with a solid content of 4-6g / L;

[0028] S20c, ultrasonic dispersion of dry SiC powder in dopamine hydrochloride solution to prepare SiC@dopamine hydrochloride dispersion;

[0029] S20d, stirring the SiC@dopamine hydrochloride dispersion liquid at room temperature, and sequentially performing centrifugal filtration, vacuum drying, and screening and grinding to obtain a nanorod-shaped material;

[0030] S20e, placing the rod-shaped material in a vacuumizing device, heating to 950-980℃, and performing vacuumizing treatment to prepare black rod-shaped SiC@dopamine powder;

[0031] Preferably, the acid liquid in step S20a is composed of sulfuric acid and nitric acid with a volume ratio of 3:1;

[0032] Preferably, the pH of the Tris-HCl buffer is 8.5-9.5;

[0033] Preferably, in step S20c, the mass concentration ratio of the dried SiC powder to the dopamine hydrochloride solution is 2 (g) / 1 (g / L);

[0034] Preferably, in step S20d, the stirring speed is 800-900 rpm, and the stirring time is 16-24 h; the particle size of the nanorod-shaped material is (450-550 nm)*(120-180 nm);

[0035] Preferably, in step S20e, the air pressure of the vacuum drying is <10 pa.

[0036] As a further scheme of the preparation method of the black electrically controlled light valve film based on nanometer SiC particles, in step S30, the molar amount of the oleic acid to the mass of the rod-shaped SiC@dopamine powder is 1 mol:(7-10) g.

[0037] As a further scheme of the preparation method of the black electrically controlled light valve film based on nanometer SiC particles, step S30 specifically comprises the following steps:

[0038] S30a, dispersing the rod-shaped SiC@dopamine powder in a solvent to prepare a mixed liquid;

[0039] S30b, adjusting the pH of the mixed liquid to 4-5 to obtain a SiC@dopamine suspension liquid;

[0040] S30c, activating the oleic acid by using an organic solvent;

[0041] S30d, adding the activated oleic acid to the SiC@dopamine suspension liquid, and sequentially performing heating and stirring, centrifugal washing, and vacuum drying to prepare a modified black nanorod-shaped SiC powder;

[0042] Preferably, the solvent in step S30a is composed of ethanol and water with a volume ratio of 1:1;

[0043] Preferably, the step S30c is specifically: dissolving oleic acid in anhydrous dichloromethane, then adding N,N'-dicyclohexyl carbodiimide and N-hydroxy succinimide, stirring uniformly at room temperature to obtain an organic solvent composed of anhydrous dichloromethane, N,N'-dicyclohexyl carbodiimide and N-hydroxy succinimide; wherein the molar ratio of oleic acid to the mass of anhydrous dichloromethane is 1 mol:8-12 g, and the molar ratio of oleic acid, N,N'-dicyclohexyl carbodiimide and N-hydroxy succinimide is 1:(1.1-1.3):(1.4-1.6).

[0044] Preferably, in the step S30d, the temperature of heating and stirring is 55-60℃; the centrifugal washing is performed using a mixture of ethanol and deionized water; the temperature of vacuum drying is 55-65℃, and the drying time is 3-5 h.

[0045] As a further scheme of the preparation method of the black electrically controlled light valve film based on nano-SiC particles, in the step S40, the dispersant is composed of acetyl citric acid tributyl ester and benzotriazole-1-tris (trimethylamino) -hexafluorophosphate.

[0046] Preferably, the volume ratio of acetyl citric acid tributyl ester to benzotriazole-1-tris (trimethylamino) -hexafluorophosphate is 1:(2-3).

[0047] As a further scheme of the preparation method of the black electrically controlled light valve film based on nano-SiC particles, in the step S40, the dispersion concentration of the modified black nanorod-shaped SiC powder in the dispersant is 3.5-4.5 wt.%.

[0048] As a further scheme of the preparation method of the black electrically controlled light valve film based on nano-SiC particles, in the step S40, the stabilizer is selected from vanadyl acetylacetonate.

[0049] Preferably, the mass ratio of vanadyl acetylacetonate to the modified black nanorod-shaped SiC powder is 0.2-0.3.

[0050] As a further scheme of the preparation method of the black electrically controlled light valve film based on nano-SiC particles, in the step S50, the silica gel is prepared from the following raw materials by weight parts:

[0051] vinyl silicone oil 65-75 parts;

[0052] methyl hydrogen silicone oil 8-12 parts;

[0053] catalyst 0.01-0.03 parts;

[0054] 3-methyl-1-butyne-3-ol 0.3-0.8 parts;

[0055] fumed silica 17-18.5 parts;

[0056] Vinyl trimethoxysilane 1-2 parts;

[0057] Hindered phenol 0.05-0.2 parts;

[0058] Preferably, the catalyst is selected from Karstedt catalyst with platinum content of 2KPPM-5KPPM;

[0059] Preferably, the particle size of fumed silica is 5-20nm;

[0060] Preferably, the mass ratio of black dispersion liquid to silica gel is 1: (1-2).

[0061] As a further scheme of the preparation method of the black electrically controlled light valve film based on nano-SiC particles, in step S60, the coating material is coated on the ITO surface of one ITO-PET conductive film, and the wet thickness of the coating layer before drying is 100-120μm.

[0062] On the other hand, a black electrically controlled light valve film based on nano-SiC particles is provided, which is prepared by the preparation method, and the black electrically controlled light valve film comprises two ITO-PET conductive films and a coating layer, the ITO surfaces of the two ITO-PET conductive films are arranged opposite to each other, and the coating layer is located between the ITO surfaces of the two ITO-PET conductive films.

[0063] The present application has the following advantages: the present application uses nano-SiC particles instead of nano-NaI / KI / I3 system, SiC as an inorganic substance is extremely insensitive to light and heat, and can withstand long-term sun exposure, high temperature and low temperature; the process of "using hydrochloric acid dopamine to modify the prepared nano-powder" is used to replace the old process of "first forming a dispersion system and then generating nano-powder", so that the rotational resistance of nano-particles under the dipole moment is extremely low, thereby reducing the working voltage from above 110V to about 36V; the black color formed by sintering the nano-SiC modified by hydrochloric acid dopamine has natural color without other colors, and will not brighten and dazzle when light passes through, and the appearance is like black sunglasses, the sunshade effect of the human eye is natural and comfortable, which is the only scheme that can realize natural black in the current electric-optical control material field; the adsorption and dispersion of alkane end in solvent and the uniform dispersion formed by the electrostatic repulsion between them replace the three-dimensional grid dispersion of nitrocellulose, and since the stability of oleic acid is much higher than that of nitrocellulose, the sensitivity of the black electrically controlled light valve film prepared by the present application to light and heat will be greatly reduced, thereby being more stable and more weather-resistant.

[0064] The black electrically controlled light valve film based on nano-SiC particles of the present application comprises two layers of ITO-PET conductive film and one layer of coating containing nano-SiC particles and silica gel, wherein the core component is inorganic nano-SiC and the encapsulating material is silica gel, which has excellent weather resistance and can withstand-40℃~120℃ and sunlight conditions for a long time and be normally used, and can be electrically controlled to switch between colorless transparent and black transparent sunglasses state, and can meet the requirements of vehicle regulations for sunshade. BRIEF DESCRIPTION OF DRAWINGS

[0065] Figure 1 is a SEM image of the modified nanorod-shaped black SiC powder described in Example 1 of the present application.

[0066] Figure 2 is a photo of the black dispersion liquid described in Example 1 of the present application.

[0067] Figure 3 is a SEM image of the black electrically controlled light valve film described in Example 1 of the present application.

[0068] Figure 4 is a comparison chart of the black electrically controlled light valve film prepared in Example 1 of the present application under on and off electric conditions. DETAILED DESCRIPTION

[0069] The technical solutions of the present application will be further described below through specific embodiments.

[0070] Unless otherwise specified, the various raw materials of the present application can be commercially available or prepared according to conventional methods in the technical field.

[0071] Example 1

[0072] I. Preparation of black SiC

[0073] The silica powder, graphite powder and NaCl-KCl (molar ratio 1:1) were uniformly ground at a mass ratio of 1:3:5 (total weight of 27 grams) with a particle size of less than 100 nm;

[0074] The 27 grams of material was placed in a corundum crucible and heated to 1000-1050℃ under Ar atmosphere at a heating rate of 5-10℃ / min and stirred for 5h;

[0075] After cooling, the material was washed by centrifugation with deionized water for 3 times, and then vacuum dried (80℃, 12h) to obtain 10 grams of black rod-shaped nano-SiC.

[0076] II. Modification by dopamine hydrochloride

[0077] 10g black rod-like SiC nanometer was added into a system of sulfuric acid / nitric acid (the concentration of sulfuric acid and nitric acid was 0.1 mol / L) with a volume ratio of 3:1, and was ultrasonically washed for 30 min and stirred at 60℃ for 2h;

[0078] Deionized water was washed for 3 times, and the precipitate was collected by centrifugation (10000 RPM, 10 min) and dried at 60℃ for 24h;

[0079] Dopamine hydrochloride was added in Tris-HCl buffer (pH was 8.5-9.5) to prepare a dopamine hydrochloride solution with a concentration of 1g / L;

[0080] The dried SiC powder was added into the dopamine hydrochloride solution (the solid content of SiC powder was 5g / L), and was ultrasonically dispersed for 30 min;

[0081] The stirring speed was 800-900 rpm at room temperature for 20h, and then the mixture was centrifuged and filtered;

[0082] The mixture was vacuum dried at 60℃ for 24h, and was sieved and ground until the size was about 500nm*150nm;

[0083] The sieved and ground powder was put into a crucible and was vacuumized (<10pa) and heated to 950-980℃ in a vacuumizing device, and 8g black rod-like SiC@ dopamine powder was obtained.

[0084] III. Modification by oleic acid

[0085] 8g black rod-like SiC@ dopamine powder was dispersed in a mixture of ethanol and water with a volume ratio of 1:1, and was ultrasonically treated for 30 min (power 600-800W);

[0086] HCl was added dropwise until the pH was 4-5, and a SiC@ dopamine suspension was obtained;

[0087] 1 mol of oleic acid was dissolved in 10g anhydrous dichloromethane, and then 1.2 mmol of N,N'-dicyclohexyl carbodiimide and 1.5 mmol of N-hydroxysuccinimide were added, and the mixture was stirred at room temperature for 2h to activate the oleic acid;

[0088] The activated oleic acid solution was slowly added into the SiC@ dopamine suspension, and the mixture was stirred in an oil bath at 55-60℃ for 6h;

[0089] The mixture was repeatedly centrifuged and washed with a mixture of ethanol / deionized water with a volume ratio of 1:1 for 5 times (8000-10000 rpm, 10 min);

[0090] The mixture was vacuum dried at 60℃ for 4h, and 6g of fully modified black rod-like SiC powder was obtained, and the yield of the black rod-like SiC powder was 6 / 27=22.22%.

[0091] The modified nanorod-like black SiC powder of the present embodiment is shown in Figure 1 .

[0092] Four, dispersion

[0093] The dispersant is configured as acetyl citric acid tributyl ester: benzotriazole-1-tris (trimethylamino) -hexafluorophosphate = 1:2.5 (volume ratio)

[0094] The modified nanorod-like black SiC powder is added to the dispersant (dispersion concentration 4% wt / wt), and 25% of vanadyl acetylacetonate based on the mass of the nanorod-like black SiC powder is added as a stabilizer, and stirred uniformly.

[0095] Ultrasonic dispersion for 10 min (power 600-800 W) to form a uniform and stable black dispersion liquid, as shown in Figure 2 .

[0096] Five, silica gel preparation

[0097] The formulation is as follows by weight parts:

[0098] Vinyl silicone oil with a viscosity of 1000 cps 70 parts;

[0099] Methyl hydrogen-containing silicone oil 10 parts;

[0100] Karstedt catalyst (platinum content 4KPPM) 0.02 parts;

[0101] 3-methyl-1-butyne-3-alcohol 0.5 parts;

[0102] Fumed silica 5-20 nm 17.88 parts;

[0103] Vinyl trimethoxysilane 1.5 parts;

[0104] Hindered phenol 0.1 parts;

[0105] After mixing the above materials, stir at room temperature for 6 h (800 rpm), filter (<0.5 μm) and store at low temperature to prepare the silica gel.

[0106] Six, film material preparation

[0107] Mix the black dispersion liquid and the silica gel according to a mass ratio of 1:1.25, then disperse with a dispersion disc at a speed of 1500 rpm for 10 min to prepare the coating material;

[0108] Use a comma coater to coat the coating material on the ITO side of an ITO-PET conductive film, with a wet thickness of 120 μm;

[0109] The coated ITO-PET conductive film is dried at 85°C for 15 minutes.

[0110] The ITO side of another ITO-PET conductive film is pressed against the coating layer of the coated ITO-PET conductive film using a press roller with a force of >5 kg to form a whole film.

[0111] The film is wound, cut and powered to obtain a black electrically controlled light valve film. The SEM image of the black electrically controlled light valve film is shown in Figure 3 .

[0112] The state of the black electrically controlled light valve film when powered on and off is shown in Figure 4 .

[0113] Example 2

[0114] This example is basically the same as Example 1, except that the mass ratio of the silica powder, graphite powder and NaCl-KCl is 1:4.5:7, and the total weight is 27 g; the yield of the nanorod-shaped black SiC powder is 8.8%.

[0115] Example 3

[0116] This example is basically the same as Example 1, except that the mass ratio of the silica powder, graphite powder and NaCl-KCl is 1:2:4, and the total weight is 27 g; the yield of the nanorod-shaped black SiC powder is 7.25%.

[0117] Example 4

[0118] This example is basically the same as Example 1, except that the molar ratio of NaCl to KCl is 1:2; the yield of the nanorod-shaped black SiC powder is 6.4%.

[0119] Example 5

[0120] This example is basically the same as Example 1, except that the wet thickness of the coating layer is 100 μm.

[0121] Example 6

[0122] This example is basically the same as Example 1, except that the solid content of the SiC powder in the dopamine hydrochloride solution is 4 g / L.

[0123] Comparative Example 1

[0124] This example is basically the same as Example 1, except that 18% of the mass of the nanometer black SiC powder is used as a stabilizer, and the settling of the dispersion liquid is increased, and the amount of particles settling after 48 h is increased from 2.5% to about 5%.

[0125] Comparative Example 2

[0126] The comparative example is basically the same as example 1, the difference is that NaI / KI / I3 system is selected, that is, no nano powder (steps one and two are omitted), and the system is directly used to replace the black rod-shaped SiC@ dopamine powder in step three.

[0127] Comparative example 3

[0128] The comparative example is basically the same as example 1, the difference is that the process of forming a dispersion system first and then generating nano powder is used instead of the dopamine hydrochloride modification process, the specific steps are as follows:

[0129] Dissolve the nitrocellulose in the solvent, the mass fraction of the nitrocellulose is 2.5wt.%, and the nano material is not modified and directly dispersed in the solvent.

[0130] Comparative example 4

[0131] The comparative example is basically the same as example 1, the difference is that the mass ratio of silica powder, graphite powder and NaCl-KCl is 1:6:5, and the total weight is 25g; the yield of nano rod-shaped black SiC powder is 4.35%, which is lower than that of example 1.

[0132] Comparative example 5

[0133] The comparative example is basically the same as example 1, the difference is that the mass ratio of silica powder, graphite powder and NaCl-KCl is 1:1:5, and the total weight is 28g; the yield of nano rod-shaped black SiC powder is 2.6%.

[0134] The proportion of graphite powder in the comparative example is lower than that in example 1, which is not enough to reduce the silica, resulting in more impurities of silica.

[0135] Comparative example 6

[0136] The comparative example is basically the same as example 1, the difference is that the mass ratio of silica powder, graphite powder and NaCl-KCl is 1:3:3, and the total weight is 31g; the yield of nano rod-shaped black SiC powder is 6.2%.

[0137] The proportion of NaCl-KCl in the comparative example is less than that in example 1, that is, the molten medium is insufficient, and the reaction between silica and graphite is not complete, resulting in a decrease in the yield of nano rod-shaped black SiC powder.

[0138] Comparative example 7

[0139] The comparative example is basically the same as example 1, the difference is that the solid content of SiC powder in the dopamine hydrochloride solution is 3g / L.

[0140] The solid content of the hydrochloric acid dopamine solution in this comparative example is too low compared to Example 1, which results in the modified nanorod-shaped black SiC powder not being dark enough and the white phase being heavily mixed with other colors.

[0141] The resulting conductive film is light in color and provides insufficient shielding when the power is off. The film parameters under power-on and power-off conditions are shown in Table 2.

[0142] Comparative Example 8

[0143] This comparative example is basically the same as Example 1, except that the amount of oleic acid used is 0.8 mol.

[0144] Insufficient oleic acid will result in poor outer layer modification of the nanorod-shaped black SiC powder, a decrease in dispersion ratio, a light-colored film, and insufficient shielding when the power is off (Table 2).

[0145] Comparative Example 9

[0146] This comparative example is basically the same as Example 1, except that the concentration of the modified nanorod-shaped black SiC powder in the dispersant is 3%.

[0147] Compared to Example 1, the conductive film material in this comparative example changes from black to gray, resulting in reduced opacity and insufficient change in transparency (contrast) when the power is switched on and off.

[0148] Comparative Example 10

[0149] This comparative example is basically the same as Example 1, except that the concentration of the modified nanorod-shaped black SiC powder in the dispersant is 5%.

[0150] The dispersant in this comparative example was too little compared to that in Example 1, resulting in incomplete dispersion of the nano black SiC powder, severe particle sedimentation, and decreased transparency (contrast) under power-on and power-off conditions.

[0151] Comparative Example 11

[0152] This comparative example is basically the same as Example 1, except that the vinyl silicone oil in the silicone is 63 parts by weight.

[0153] The conductive film material prepared in this comparative example has too high hardness. After the film material is cured, it cannot be rolled up and bent. It is easy to crack and break when bent, forming ice flower patterns.

[0154] Comparative Example 12

[0155] This comparative example is basically the same as Example 1, except that the weight of the methyl hydrogen silicone oil in the silicone is 7 parts.

[0156] The conductive film material of the present comparative example collapses under stress, especially pressure, resulting in failure under power-on condition. The reason is that the methyl-containing silicone oil is too little, the film layer structure is loose, and the hardness of the conductive film material is insufficient.

[0157] Comparative Example 13

[0158] The present comparative example is basically the same as Example 1, except that the wet thickness of the coating layer is 140 μm.

[0159] In the present comparative example, the coating layer is too thick after curing, resulting in a substantial increase in working voltage. The results are shown in Table 2.

[0160] Comparative Example 14

[0161] The present comparative example is basically the same as Example 1, except that the wet thickness of the coating layer is 90 μm.

[0162] In the present comparative example, the coating layer is too thin after curing, resulting in too light color of the film layer, insufficient shielding under power-off condition. The results are shown in Table 2.

[0163] Comparative Example 15

[0164] The present comparative example is basically the same as Example 1, except that nitrocellulose is used instead of oleic acid.

[0165] The parameters of the electro-controlled light valve film samples prepared in Examples 1-6 and Comparative Examples 1-15 above were tested according to the standard GB9656-2021 (wherein the hardness was tested by using a hardness pen), and the results are shown in Tables 1-2.

[0166] Table 1. Film material parameters of Examples 1-6 and Comparative Examples 1-15

[0167]

[0168] Table 2. Film material parameters of Comparative Examples 6-15

[0169]

[0170] According to the above data comparison, the black electro-controlled light valve film prepared by the preparation method of the present application has excellent weather resistance and can realize electrically controlled switching between colorless transparent and black transparent sunglasses states.

[0171] The above examples are only used to illustrate the detailed method of the present application, and the present application is not limited to the above detailed method, i.e. it does not mean that the present application must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvement of the present application, equivalent replacement of each raw material of the product of the present application, addition of auxiliary ingredients, selection of specific methods, etc. all fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for producing a black electrochromic light valve film based on nano-SiC particles, characterized in that, The method comprises the following steps: S10, taking silica powder, graphite powder and NaCl-KCl with a mass ratio of 1:(2-5):(4-8) as raw materials to prepare rod-shaped SiC, wherein the molar ratio of NaCl to KCl is 1:(0.5-2); S20, pretreating the rod-shaped SiC, then modifying the rod-shaped SiC by using a dopamine hydrochloride solution, and post-treating to obtain black rod-shaped SiC@ dopamine powder, wherein the step S20 comprises the following steps: S20a, adding the rod-shaped SiC into an acid solution with a temperature of 50-70 DEG C to perform ultrasonic washing, and drying the obtained precipitate to obtain dry SiC powder; S20b, adding the dopamine hydrochloride into a Tris-HCl buffer solution to obtain a dopamine hydrochloride solution with a solid content of 4-6 g / L; S20c, ultrasonic dispersing the dry SiC powder in the dopamine hydrochloride solution to obtain a SiC@ dopamine hydrochloride dispersion; S20d, stirring the SiC@ dopamine hydrochloride dispersion at room temperature, and sequentially performing centrifugal filtration, vacuum drying and screening and grinding to obtain a nanorod-shaped material; S20e, placing the rod-shaped material in a vacuumizing device, heating to 950-980 DEG C to perform vacuumizing treatment, and obtaining black rod-shaped SiC@ dopamine powder; S30, modifying the rod-shaped SiC@ dopamine by using oleic acid to obtain modified black nanorod-shaped SiC powder; S40, dispersing the modified black nanorod-shaped SiC powder obtained in the step S30 in a dispersant, and adding a stabilizer to obtain a black dispersion; S50, providing silica gel, mixing and uniformly dispersing the black dispersion with the silica gel to obtain a coating material; S60, providing two ITO-PET conductive films, coating the coating material on the ITO surface of one of the ITO-PET conductive films and performing drying treatment to form a coating layer, then oppositely arranging the ITO surface of the other ITO-PET conductive film to the coating layer and performing pressing treatment to obtain a black electrically controlled light valve film.

2. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 1, characterized in that, The step S10 comprises the following steps: S10a, uniformly grinding the silica powder, graphite powder and NaCl-KCl; S10b, heating to 1000-1500 DEG C under Ar atmosphere and stirring, and the heating rate is 5-10 DEG C / min; S10c, centrifugal washing and vacuum drying at 70-85 DEG C to obtain the rod-shaped SiC; The particle size of the silica powder is less than 100 nm.

3. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 1, characterized in that, The acid solution in the step S20a is composed of sulfuric acid and nitric acid with a volume ratio of 3:

1.

4. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 1, characterized in that, The pH of the Tris-HCl buffer solution is 8.5-9.

5.

5. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 1, characterized in that, In the step S20c, the mass ratio of the dry SiC powder to the mass concentration of the dopamine hydrochloride solution is 2(g) / 1(g / L).

6. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 1, characterized in that, In step S20d, the stirring speed is 800-900 rpm, the stirring time is 16-24 h; the particle size of the nanorod-like material is (450-550 nm) (120-180 nm).

7. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 1, characterized in that, In the step S20e, the air pressure of the vacuum drying is less than 10 pa.

8. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 1, characterized in that, In the step S30, the molar ratio of the oleic acid to the mass of the rod-shaped SiC@ dopamine powder is 1 mol:(7-10 g).

9. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 8, characterized in that, The step S30 comprises the following steps: S30a, dispersing the rod-shaped SiC@ dopamine powder in a solvent to obtain a mixed solution; S30b, adjust the pH of the mixed solution to 4-5 to obtain a SiC@ dopamine suspension liquid; S30c, activate the oleic acid with an organic solvent; S30d, add the activated oleic acid to the SiC@ dopamine suspension liquid, and sequentially perform heating stirring, centrifugal washing, and vacuum drying to obtain the modified black nanorod SiC powder.

10. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 9, characterized in that, The solvent in step S30a is composed of ethanol and water in a volume ratio of 1:

1.

11. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 9, characterized in that, Step S30c specifically comprises: dissolving the oleic acid in anhydrous dichloromethane, then adding N,N'-dicyclohexyl carbodiimide and N-hydroxy succinimide, stirring uniformly at room temperature to obtain an organic solvent composed of anhydrous dichloromethane, N,N'-dicyclohexyl carbodiimide and N-hydroxy succinimide; wherein the molar ratio of the oleic acid to the mass of the anhydrous dichloromethane is 1 mol:8-12 g, and the molar ratio of the oleic acid, N,N'-dicyclohexyl carbodiimide and N-hydroxy succinimide is 1: (1.1-1.3): (1.4-1.6).

12. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 9, characterized in that, In step S30d, the temperature of the heating stirring is 55-60℃; the centrifugal washing is performed with a mixed solution of ethanol and deionized water; the temperature of the vacuum drying is 55-65℃, and the drying time is 3-5h.

13. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 1, characterized in that, In step S40, the dispersant is composed of acetyl citric acid tributyl ester and benzotriazole-1-tris (trimethylamino) -hexafluorophosphate.

14. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 13, characterized in that, The volume ratio of the acetyl citric acid tributyl ester and the benzotriazole-1-tris (trimethylamino) -hexafluorophosphate is 1: (2-3).

15. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 1, characterized in that, In step S40, the dispersion concentration of the modified black nanorod SiC powder in the dispersant is 3.5-4.5wt.%.

16. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 1, characterized in that, In step S40, the stabilizer is selected from vanadyl acetylacetonate.

17. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 16, characterized in that, The mass ratio of the vanadyl acetylacetonate to the modified black nanorod SiC powder is 0.2-0.

3.

18. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 1, characterized in that, In step S50, the silica gel is prepared from the following raw materials in parts by weight: vinyl silicone oil 65-75 parts; methyl hydrogen silicone oil 8-12 parts; catalyst 0.01-0.03 parts; 3-methyl-1-butyne-3-ol 0.3-0.8 parts; fumed silica 17-18.5 parts; vinyl trimethoxysilane 1-2 parts; hindered phenol 0.05-0.2 parts.

19. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 18, characterized in that, The catalyst is selected from Karstedt catalyst with a platinum content of 2Kppm-5Kppm.

20. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 18, characterized in that, The particle size of the fumed silica is 5-20nm.

21. The method for preparing a black electro-optical light valve film based on nano-SiC particles according to claim 18, characterized in that, The mass ratio of the black dispersion liquid to the silica gel is 1: (1-2).

22. A method of producing a nano-SiC particle-based black electrochromic light valve film according to any one of claims 1 to 21, characterized by, In step S60, the coating material is coated on the ITO surface of one ITO-PET conductive film, and the wet thickness of the coating layer before drying is 100-120μm.

23. A black electrochromic light valve film based on nano-SiC particles, characterized in that, The black electrically controlled light valve film is prepared by the preparation method of any one of claims 1 to 21, and comprises two ITO-PET conductive films and a coating layer, the ITO surfaces of the two ITO-PET conductive films are arranged opposite to each other, and the coating layer is located between the ITO surfaces of the two ITO-PET conductive films.

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