High-durability hydrophobic coating applied to low-temperature condition and preparation method of high-durability hydrophobic coating

Abstract

The invention relates to the technical field of preparation of hydrophobic coatings, in particular to a high-durability hydrophobic coating applied to a low-temperature condition and a preparation method of the high-durability hydrophobic coating. The preparation method comprises the following steps: S1, synthesizing a fluorosilicone modified polyurethane polymer solution; s2, synthesizing fluorine modified silicon dioxide nano particles; s3, preparation of the hydrophobic coating: adding the fluorine-modified silicon dioxide nanoparticles into an organic solvent for ultrasonic dispersion, then adding the fluorine-silicon modified polyurethane polymer solution, and stirring at a high speed to obtain the high-durability hydrophobic coating. The prepared hydrophobic coating has no influence on the optical performance of a transparent part after being prepared, and the hydrophobic performance is hardly changed after high-temperature, low-temperature, temperature impact, raining and solar radiation tests, which shows that the hydrophobic coating has excellent low-temperature durability.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of hydrophobic coating preparation, and in particular to a high-durability hydrophobic coating applied under low-temperature conditions and a preparation method thereof. BACKGROUND

[0002] In the fields of aviation, rail transportation, optical equipment and infrastructure in cold regions, the surfaces of transparent materials (such as aircraft windshields, high-speed rail front windshield glass, infrared device windows, traffic monitoring lenses and the like) often face problems such as low-temperature icing, fogging, dirt adhesion and the like, which seriously affect the optical performance and operation safety. Traditional hydrophobic coatings perform well in normal temperature environments, but in extremely low-temperature environments below-40 DEG C, they are prone to problems such as embrittlement cracking, adhesion reduction, and sudden reduction of hydrophobic performance, and it is difficult to balance long-term durability and high light transmittance. The existing technology has the following bottlenecks:

[0003] (1) Damage of low-temperature environment to the hydrophobic coating: the glass transition temperature of most polymer materials (such as acrylic resin, silicone) is higher than-40 DEG C, the molecular chain segment movement is frozen at low temperature, resulting in loss of coating toughness, and micro-cracks are easily produced under thermal stress or mechanical impact, which destroys the micro-nano hydrophobic structure on the surface; the difference in the thermal expansion coefficient between the substrate and the coating is amplified at low temperature, and the interface stress accumulates to cause peeling; the crystallization tendency of fluorocarbon chain segments is enhanced at low temperature, the surface energy rises, and the static contact angle significantly decreases;

[0004] (2) The silicone resin system has low surface energy and good flexibility, but has low hardness, poor wear resistance, and the siloxane bond is prone to hydrolysis and rupture in a low-temperature and humid environment, resulting in reduced service life; the fluorocarbon resin system has ultra-low surface energy and chemical inertness, but the fluorocarbon chain has high rigidity and significant low-temperature brittleness, and has weak adhesion with the substrate; in the existing technology, silica nanoparticles are dispersed in the resin matrix to build a micro-nano rough structure, but the particles are prone to agglomeration, the organic / inorganic interface has poor compatibility, and the particles are prone to falling off after low-temperature cycling.

[0005] The urgent demand for high-performance low-temperature hydrophobic coatings in the industry is as follows: in the field of aviation: the helicopter porthole is prone to frosting at high altitudes, the traditional deicing system has high energy consumption, and a high-performance hydrophobic coating is needed; the infrared window surface of optical equipment requires a higher light transmittance; the front windshield glass of rail transportation needs to pass the rain test and have no fragmentation under ball impact; the camera lens requires high ice adhesion resistance and is resistant to ultraviolet aging.

[0006] Based on the above problems, it is urgent to develop a coating material that has low-temperature toughness, high light transmittance, long-term hydrophobicity and full-environment resistance, fills the industry gap of long-term hydrophobic coatings in extremely low-temperature environments, and provides core material support for reliable operation of equipment in cold regions. SUMMARY

[0007] The embodiment of the present application provides a kind of to at least solve one of the problems existing in the related art. To achieve this object, the present application is realized by the following technical solutions.

[0008] The present application provides a kind of preparation method of high durability hydrophobic coating applied under low temperature condition, comprising the following steps:

[0009] S1. Synthesis of fluorine-silicon modified polyurethane polymer solution;

[0010] S2. Synthesis of fluorine modified silica nanoparticles;

[0011] S3. Preparation of hydrophobic coating: fluorine modified silica nanoparticles are added to organic solvent and ultrasonically dispersed, then fluorine-silicon modified polyurethane polymer solution is added, and high durability hydrophobic coating is obtained by high-speed stirring.

[0012] In some preferred embodiments, the synthesis of the fluorine-silicon modified polyurethane polymer solution specifically comprises:

[0013] S11. After dehydration, polycarbonate diol, polytetrahydrofuran ether diol and perfluoropolyether diol are added to a reaction kettle with isophorone diisocyanate and 4,4'-diphenyl methane diisocyanate, a catalyst is added, and the reaction is carried out by temperature rising and stirring to generate an isocyanate group terminated prepolymer;

[0014] S12. The reaction system is cooled, and a hindered phenol chain extender and 1,4-butanediol are sequentially added, and the reaction is continued by stirring, and hydroxyl-terminated polydimethylsiloxane and hydroxyl-terminated dimethyl diphenyl siloxane are added, and the reaction is carried out by temperature rising and stirring to obtain a fluorine-silicon modified polyurethane polymer solution.

[0015] In some preferred embodiments, the mass ratio of polycarbonate diol, polytetrahydrofuran ether diol and perfluoropolyether diol is (30-40):(20-30):(5-10).

[0016] Polycarbonate diol as the main soft segment provides excellent hydrolysis resistance, mechanical strength and low temperature toughness. Its rigid carbonate group can form a regular microphase separation structure. However, too high proportion may cause the material to be too hard, and it needs to be compounded with flexible soft segment polytetrahydrofuran ether diol to balance. Polytetrahydrofuran ether diol imparts flexibility and low temperature folding resistance to the material, and the ether bond structure enhances dynamic performance. By controlling the compounding ratio with polycarbonate diol, the rigidity of the material is avoided to be excessively reduced.

[0017] In some preferred embodiments, the mass ratio of isophorone diisocyanate and 4,4'-diphenyl methane diisocyanate is (15-25):(5-15).

[0018] Isophorone diisocyanate as the main isocyanate monomer provides weather resistance and anti-yellowing property, and cooperates with the fluorine / silicon component to reduce surface energy. 4,4'-diphenyl methane diisocyanate enhances the rigidity of the hard segment, and improves the tensile strength and wear resistance. The two are synergistically compounded, and both weather resistance and mechanical properties are considered.

[0019] In some preferred embodiments, the mass ratio of the hydroxyl-terminated polydimethylsiloxane and the hydroxyl-terminated dimethyl diphenyl siloxane is (5-10):(1-5).

[0020] The hydroxyl-terminated polydimethylsiloxane improves hydrophobicity and thermal stability through dynamic crosslinking of siloxane, and reduces water absorption. The phenyl in the hydroxyl-terminated dimethyl diphenyl siloxane enhances the ultraviolet resistance, and cooperates with the hydroxyl-terminated polydimethylsiloxane to optimize the surface roughness.

[0021] In some preferred embodiments, the synthesis of the fluorine-modified silica nanoparticles specifically comprises:

[0022] S21. Ultrasonic dispersion of silica nanoparticles and ethanol to form a silica dispersion liquid;

[0023] S22. Long-chain fluorosilanol hydrolysate is prepared by mixing tridecafluorooctyltriethoxysilane with ethanol and adjusting the pH to 3.

[0024] S23. The silica dispersion liquid is added to the long-chain fluorosilanol hydrolysate, and trifluoropropyltriethoxysilane is added. After stirring, the reaction solution is centrifuged, the precipitate is collected and washed with ethanol, and vacuum drying box is used to obtain fluorine-modified silica nanoparticles.

[0025] In some preferred embodiments, the mass ratio of the silica nanoparticles and tridecafluorooctyltriethoxysilane, trifluoropropyltriethoxysilane is (15-25):(1-5):(0.5-3).

[0026] The fluorine-modified silica nanoparticles mainly function by grafting to the surface of silica through hydrolysis and condensation reaction, introducing fluorocarbon chains to reduce surface energy. The long-chain fluorosilane constructs a low surface energy layer; the short-chain fluorosilane added later fills the pores to form a dense grafted structure.

[0027] In some preferred embodiments, the mass ratio of the fluorine-modified silica nanoparticles and the fluorosilicon-modified polyurethane high molecular solution is 1:(3-10).

[0028] In some preferred embodiments, the solid content of the hydrophobic coating is 8-15%.

[0029] The application also provides a high-durability hydrophobic coating prepared by the above preparation method.

[0030] The embodiments of the present application have the following beneficial effects:

[0031] The hydrophobic coating prepared by the present application has no influence on the optical performance of the transparent piece after preparation, and the hydrophobic performance almost does not change after high temperature, low temperature, temperature shock, rain test, and solar radiation test. In addition, the film layer of the hydrophobic sample has no cracks, bubbles, wrinkles and peeling after the hydrophobic coating is placed in an environment of minus 56℃ for 2 months, and the average value of the static contact angle of the surface of the test piece is reduced by 1.36°, indicating that the low-temperature durability of the hydrophobic coating is excellent. DETAILED DESCRIPTION

[0032] To make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the embodiments of the present application are described in detail below. However, those skilled in the art can understand that in the embodiments of the present application, many technical details are proposed in order to make the readers better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed by the present application can be realized. The division of the following embodiments is for the convenience of description, and should not constitute any limitation on the specific implementation of the present application, and the embodiments can be combined and quoted with each other without contradiction.

[0033] Polycarbonate diol, Mn = 2000, purchased from Shanghai Macklin Biochemical Science and Technology Co., Ltd.

[0034] Polytetrahydrofuran ether diol, Mn = 1000, purchased from Shandong Changhui Chemical Co., Ltd.

[0035] Perfluoropolyether diol, Mn = 1000, purchased from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd.

[0036] Isophorone diisocyanate, purchased from Shanghai Macklin Biochemical Science and Technology Co., Ltd.

[0037] 4,4'-diphenyl methane diisocyanate, purchased from Shanghai Macklin Biochemical Science and Technology Co., Ltd.

[0038] Hydroxyl-terminated polydimethylsiloxane, purchased from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd.

[0039] Hydroxyl-terminated dimethyl diphenyl siloxane, purchased from Guangdong Shengke Biochemical Technology Co., Ltd.

[0040] Hindered phenol chain extender 3,5-di-tert-butyl-4-hydroxyphenyl propionic acid, purchased from Beijing Bailingwei Technology Co., Ltd.

[0041] Dibutyltin dilaurate, purchased from Shanghai Araldin Biochemical Technology Co., Ltd.

[0042] Trifluoropropyltriethoxysilane was purchased from Hangzhou Jieheng Chemical Co., Ltd.

[0043] Tridecafluorooctyltriethoxysilane was purchased from Hubei Xindesheng Materials Technology Co., Ltd.

[0044] Silica nanoparticles were purchased from Guangzhou Jinsheng Chemical Co., Ltd.

[0045] Example 1

[0046] This embodiment provides a high-durability hydrophobic coating applicable to low-temperature conditions, the preparation method of which includes:

[0047] S1. Synthesis of Fluorosilicone Modified Polyurethane Polymer Solution

[0048] 35g of polycarbonate diol, 25g of polytetrahydrofuran ether diol, and 8g of perfluoropolyether diol were vacuum dehydrated at 90°C for 2 hours. The dehydrated product was then added to a reactor along with 20g of isophorone diisocyanate and 10g of 4,4'-diphenylmethane diisocyanate. The isocyanate index R value (NCO / OH) was controlled to be 1.5. 0.05g of dibutyltin dilaurate catalyst was added. The mixture was stirred at 400rpm for 3 hours under nitrogen protection at 80°C to generate an isocyanate-terminated prepolymer.

[0049] The reaction system was cooled to 55°C, and 1.5g of hindered phenol chain extender and 1.5g of 1,4-butanediol were added sequentially. The reaction was stirred for 1 hour. Then, 6g of hydroxyl-terminated polydimethylsiloxane and 2g of hydroxyl-terminated dimethyldiphenylsiloxane were added. The temperature was raised to 70°C and the reaction was stirred for 2 hours to obtain a fluorosilicone modified polyurethane polymer solution for later use.

[0050] S2. Synthesis of Fluorine-Modified Silica Nanoparticles

[0051] 20g of 50nm silica nanoparticles were mixed with ethanol at a mass ratio of 1:5 and ultrasonically dispersed at 300W for 25 minutes to form a silica dispersion.

[0052] 3g of tridecafluorooctyltriethoxysilane was mixed with ethanol at a mass ratio of 1:15, and acetic acid was added to adjust the pH to 3. The mixture was stirred at 300 rpm for 0.5 hours at room temperature to prepare a long-chain fluorosilane hydrolysate.

[0053] The silica dispersion was slowly added to the hydrolysate of long-chain fluorosilane and mechanically stirred at 600 rpm for 3 hours at 70°C. Then, 1 g of trifluoropropyltriethoxysilane was added and the reaction was continued for 3.5 hours to allow the fluorosilane molecules to be completely grafted onto the silica surface. The reaction solution was centrifuged at 10,000 rpm for 15 minutes, the precipitate was collected and washed three times with ethanol to remove unreacted substances, and then dried to constant weight in a vacuum drying oven at 80°C to obtain fluorine-modified silica nanoparticles.

[0054] S3. Preparation of hydrophobic coatings

[0055] Weigh 10g of fluorine-modified silica nanoparticles and add them to butyl acetate for ultrasonic dispersion for 30 minutes; then add 50g of fluorine-silicone-modified polyurethane polymer solution and stir at 800rpm for 1 hour to prepare a hydrophobic coating with a solid content of about 10%.

[0056] Example 2

[0057] This embodiment provides a high-durability hydrophobic coating applicable to low-temperature conditions, the preparation method of which includes:

[0058] S1. Synthesis of Fluorosilicone Modified Polyurethane Polymer Solution

[0059] 30g of polycarbonate diol (Mn=2000), 20g of polytetrahydrofuran ether diol (Mn=1000), and 5g of perfluoropolyether diol (Mn=1000) were vacuum dehydrated at 90℃ for 2 hours. After dehydration, 15g of isophorone diisocyanate and 5g of 4,4'-diphenylmethane diisocyanate were added to a reaction vessel. The isocyanate index R value (NCO / OH) was controlled to be 1.5. 0.03g of dibutyltin dilaurate catalyst was added. The reaction was carried out at 80℃ under nitrogen protection and stirred at 300rpm for 3 hours to generate terminal isocyanate prepolymer.

[0060] The reaction system was cooled to 55°C, and hindered phenol chain extender AO-80 (1.0 g) and 1,4-butanediol (1.0 g) were added sequentially. The reaction was stirred for 1 hour. Then, 5 g of hydroxyl-terminated polydimethylsiloxane and 1 g of hydroxyl-terminated dimethyldiphenylsiloxane were added, and the temperature was raised to 70°C. The reaction was stirred for 2 hours to obtain a fluorosilicone modified polyurethane polymer solution for later use.

[0061] S2. Synthesis of Fluorine-Modified Silica Nanoparticles

[0062] 15g of 50nm silica nanoparticles were mixed with ethanol at a mass ratio of 1:5 and ultrasonically dispersed at 300W for 30 minutes to form a silica dispersion.

[0063] 1 g of tridecafluorooctyltriethoxysilane was mixed with ethanol at a mass ratio of 1:15, and acetic acid was added to adjust the pH to 3. The mixture was stirred at 300 rpm for 0.5 hours at room temperature to prepare a long-chain fluorosilanol hydrolysate.

[0064] The silica dispersion was slowly added to the hydrolysate of long-chain fluorosilanol, and the mixture was mechanically stirred at 500 rpm for 3 hours at 70°C. Then, 0.5 g of trifluoropropyltriethoxysilane was added, and the mixture was stirred for another 3 hours. The reaction solution was centrifuged at 10,000 rpm for 15 minutes, the precipitate was collected, washed three times with ethanol, and dried to constant weight in a vacuum drying oven at 80°C to obtain fluorine-modified silica nanoparticles.

[0065] S3. Preparation of hydrophobic coatings

[0066] Weigh 5g of fluorine-modified silica nanoparticles and add them to 40g of butyl acetate for ultrasonic dispersion for 30 minutes; then add 15g of fluorine-silicone-modified polyurethane polymer solution and stir at 800rpm for 1 hour to prepare a hydrophobic coating with a solid content of 8%.

[0067] Example 3

[0068] This embodiment provides a high-durability hydrophobic coating applicable to low-temperature conditions, the preparation method of which includes:

[0069] S1. Synthesis of Fluorosilicone Modified Polyurethane Polymer Solution

[0070] 40g of polycarbonate diol (Mn=2000), 30g of polytetrahydrofuran ether diol (Mn=1000), and 10g of perfluoropolyether diol (Mn=1000) were vacuum dehydrated at 90℃ for 2 hours. After dehydration, 25g of isophorone diisocyanate and 15g of 4,4'-diphenylmethane diisocyanate were added to a reaction vessel. The isocyanate index R value (NCO / OH) was controlled to be 1.5. 0.08g of dibutyltin dilaurate catalyst was added. The reaction was carried out at 80℃ under nitrogen protection and stirred at 400rpm for 3 hours to generate terminal isocyanate prepolymer.

[0071] The reaction system was cooled to 55°C, and hindered phenol chain extender AO-80 (2.0 g) and 1,4-butanediol (2.0 g) were added sequentially. The reaction was stirred for 1 hour. Then, 10 g of hydroxyl-terminated polydimethylsiloxane and 5 g of hydroxyl-terminated dimethyldiphenylsiloxane were added, and the temperature was raised to 75°C. The reaction was stirred for 2 hours to obtain a fluorosilicone modified polyurethane polymer solution for later use.

[0072] S2. Synthesis of Fluorine-Modified Silica Nanoparticles

[0073] 25g of 50nm silica nanoparticles were mixed with ethanol at a mass ratio of 1:5 and ultrasonically dispersed at 300W for 30 minutes to form a silica dispersion.

[0074] 5g of tridecafluorooctyltriethoxysilane was mixed with ethanol at a mass ratio of 1:15, and hydrochloric acid was added to adjust the pH to 2.5. The mixture was stirred at 300 rpm for 0.5 hours at room temperature to prepare a long-chain fluorosilanol hydrolysate.

[0075] The silica dispersion was slowly added to the hydrolysate of long-chain fluorosilane and mechanically stirred at 600 rpm for 4 hours at 70°C. Then, 3 g of trifluoropropyltriethoxysilane was added and the reaction was continued for another 4 hours. The reaction solution was centrifuged at 15,000 rpm for 15 minutes, the precipitate was collected, washed three times with ethanol, and dried to constant weight in a vacuum drying oven at 80°C to obtain fluorine-modified silica nanoparticles.

[0076] S3. Preparation of hydrophobic coatings

[0077] Weigh 5g of fluorine-modified silica nanoparticles and add them to 28g of butyl acetate for ultrasonic dispersion for 30 minutes; then add 50g of fluorine-silicone-modified polyurethane polymer solution and stir at 1200rpm for 1 hour to prepare a hydrophobic coating with a solid content of 15%.

[0078] Example 4

[0079] This embodiment provides a high-durability hydrophobic coating applicable to low-temperature conditions, the preparation method of which includes:

[0080] S1. Synthesis of Fluorosilicone Modified Polyurethane Polymer Solution

[0081] 38g of polycarbonate diol (Mn=2000), 22g of polytetrahydrofuran ether diol (Mn=1000), and 6g of perfluoropolyether diol (Mn=1000) were vacuum dehydrated at 90℃ for 2 hours. After dehydration, 18g of isophorone diisocyanate and 8g of 4,4'-diphenylmethane diisocyanate were added to a reaction vessel. The isocyanate index R value (NCO / OH) was controlled to be 1.5. 0.06g of dibutyltin dilaurate catalyst was added. The reaction was carried out using a step-by-step heating process: 70℃ (1 hour) → 85℃ (2 hours) under nitrogen protection with stirring at 400 rpm to generate terminal isocyanate prepolymer.

[0082] The reaction system was cooled to 55°C, and hindered phenol chain extender AO-80 (1.8g) and 1,4-butanediol (1.5g) were added sequentially. The reaction was stirred for 1 hour. Then, 7g of hydroxyl-terminated polydimethylsiloxane and 3g of hydroxyl-terminated dimethyldiphenylsiloxane were added, and the temperature was raised to 70°C. The reaction was stirred for 2 hours to obtain a fluorosilicone modified polyurethane polymer solution for later use.

[0083] S2. Synthesis of Fluorine-Modified Silica Nanoparticles

[0084] 18g of 50nm silica nanoparticles were mixed with ethanol at a mass ratio of 1:5 and ultrasonically dispersed at 300W for 25 minutes to form a silica dispersion.

[0085] 2g of tridecafluorooctyltriethoxysilane was mixed with ethanol at a mass ratio of 1:15, acetic acid was added to adjust the pH to 3, and 0.1g of triethylamine was added as a coupling promoter. The mixture was stirred at 300 rpm for 0.5 hours at room temperature to prepare a long-chain fluorosilanol hydrolysate.

[0086] The silica dispersion was slowly added to the hydrolysate of long-chain fluorosilane and mechanically stirred at 600 rpm at 70°C for 3.5 hours. Then, 1 g of trifluoropropyltriethoxysilane was added and the reaction was stirred for another 3 hours. The reaction solution was centrifuged at 12000 rpm for 15 minutes, the precipitate was collected, washed three times with ethanol, and dried to constant weight in a vacuum drying oven at 80°C to obtain fluorine-modified silica nanoparticles.

[0087] S3. Preparation of hydrophobic coatings

[0088] Weigh 8g of fluorine-modified silica nanoparticles and add them to 45g of butyl acetate for ultrasonic dispersion for 30 minutes; then add 48g of fluorine-silicone-modified polyurethane polymer solution and use a two-stage stirring process: first, premix at 600rpm for 10 minutes, and then stir at 1200rpm for 50 minutes to prepare a hydrophobic coating with a solid content of 12%.

[0089] Comparative Example 1

[0090] Refer to Example 1, but with the following changes: (fluorine component missing)

[0091] The perfluoropolyether diol was replaced with an equal mass of polytetrahydrofuran ether diol (i.e., 35g of polycarbonate diol and 33g of polytetrahydrofuran ether diol), and after dehydration, it was reacted with 20g of isophorone diisocyanate and 10g of 4,4'-diphenylmethane diisocyanate. The subsequent steps were the same as in Example 1.

[0092] Comparative Example 2

[0093] Refer to Example 1, but with the following changes: (Silica nanoparticles remain unchanged)

[0094] In step S2, 20g of silica nanoparticles were mixed with ethanol at a mass ratio of 1:5. After ultrasonic dispersion at 300W for 25 minutes, the dispersion was centrifuged at 10000rpm for 15 minutes. The precipitate was collected, washed three times with ethanol, and dried under vacuum at 80℃ to constant weight to obtain unmodified silica nanoparticles. The remaining steps were the same as in Example 1.

[0095] Comparative Example 3

[0096] Referring to Example 1, but with the following changes: (imbalance in the proportion of siloxanes)

[0097] In step S1, the amount of hydroxyl-terminated polydimethylsiloxane is changed to 20g, and the amount of hydroxyl-terminated dimethyldiphenylsiloxane is changed to 1g (i.e., the mass ratio is 20:1). The remaining raw material ratios and reaction steps are the same as in Example 1.

[0098] Comparative Example 4 (without hindered phenol chain extender)

[0099] Refer to Example 1, but with the following changes:

[0100] In step S1, the hindered phenol chain extender (3,5-di-tert-butyl-4-hydroxyphenylpropionic acid) is replaced with an equimolar amount of 1,4-butanediol (approximately 3.0 g). The remaining raw material ratios and reaction steps are the same as in Example 1.

[0101] Comparative Example 5 (dimethyldiphenylsiloxane deletion)

[0102] Refer to Example 1, but with the following changes:

[0103] In step S1, hydroxyl-terminated dimethyldiphenylsiloxane is removed (i.e., its amount is 0), and the amount of hydroxyl-terminated polydimethylsiloxane is increased to 8g (keeping the total siloxane mass approximately the same as in Example 1). The remaining raw material ratios and reaction steps are the same as in Example 1.

[0104] Performance testing

[0105] After cleaning the glass with a neutral detergent, the above-mentioned hydrophobic coating was applied to the outer surface of the glass substrate by spraying. After curing at room temperature for 2-3 hours, a highly durable hydrophobic transparent material was obtained. The following tests were performed sequentially, and the test results are shown in Table 1.

[0106] Light transmittance: Tested according to GB / T2410-2008 "Determination of light transmittance and haze of transparent plastics".

[0107] Haze test: Tested according to GB / T2410-2008 "Determination of light transmittance and haze of transparent plastics".

[0108] Static contact angle: The test shall be conducted in accordance with the relevant provisions of GB / T 30693-2014 "Measurement of contact angle between plastic film and water".

[0109] High temperature test: Conduct high temperature storage test according to GJB150.3A-2009 "Laboratory Environmental Test Methods for Military Equipment Part 3: High Temperature Test" and test the hydrophobicity after the test.

[0110] Low temperature test: The test shall be carried out in accordance with the relevant provisions of GJB150.4A-2009 "Laboratory Environmental Test Methods for Military Equipment Part 4: Low Temperature Test" and the hydrophobic performance shall be tested after the test.

[0111] Temperature shock test: The test shall be carried out in accordance with the relevant provisions of GJB150.5A-2009 "Laboratory Environmental Test Methods for Military Equipment Part 5: Temperature Shock Test" and the hydrophobic performance shall be tested after the test.

[0112] Rain test: The test shall be conducted in accordance with the relevant provisions of GJB150.8A-2009 "Laboratory Environmental Test Methods for Military Equipment - Rain Test" Procedure I, and the hydrophobic performance shall be tested after the test.

[0113] Solar irradiation test: The test shall be conducted in accordance with the relevant provisions of GJB150.7A-2009 "Laboratory Environmental Test Methods for Military Equipment - Solar Irradiation Test" and the hydrophobic performance shall be tested after the test.

[0114] Hydrophobic performance durability test: The prepared hydrophobic sample was placed at -56℃ for two months to test its hydrophobic performance.

[0115] Table 1

[0116]

[0117] As shown in Table 1, the hydrophobic coating does not affect the optical properties of the transparent part after preparation. After high temperature, low temperature, temperature shock, rain and solar radiation tests, the hydrophobic properties are almost unchanged. In addition, after the hydrophobic coating was placed at -56℃ for 2 months, the film layer of the hydrophobic sample did not crack, bubble, wrinkle or peel off. The average static contact angle of the test piece surface decreased by 1.36°, indicating that the hydrophobic coating has excellent low temperature durability.

[0118] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a highly durable hydrophobic coating for use under low-temperature conditions, characterized in that, Includes the following steps: S1. Synthesis of fluorosilicone modified polyurethane polymer solution; S2. Synthesis of fluorine-modified silica nanoparticles; S3. Preparation of hydrophobic coating: Fluorine-modified silica nanoparticles are added to an organic solvent and ultrasonically dispersed, then fluorosilicone-modified polyurethane polymer solution is added and stirred at high speed to obtain a high-durability hydrophobic coating.

2. The preparation method according to claim 1, characterized in that, The synthesis of the fluorosilicone-modified polyurethane polymer solution specifically includes: S11. Polycarbonate diol, polytetrahydrofuran ether diol, and perfluoropolyether diol are dehydrated and then added to a reaction vessel along with isophorone diisocyanate and 4,4'-diphenylmethane diisocyanate. A catalyst is added, the temperature is raised, and the mixture is stirred to generate a terminal isocyanate group prepolymer. S12. Cool the reaction system, add hindered phenol chain extender and 1,4-butanediol in sequence, continue stirring the reaction, add hydroxyl-terminated polydimethylsiloxane and hydroxyl-terminated dimethyldiphenylsiloxane, heat and stir the reaction to obtain fluorosilicone modified polyurethane polymer solution.

3. The preparation method according to claim 2, characterized in that, The mass ratio of the polycarbonate diol, polytetrahydrofuran ether diol, and perfluoropolyether diol is (30-40):(20-30):(5-10).

4. The preparation method according to claim 3, characterized in that, The mass ratio of isophorone diisocyanate to 4,4'-diphenylmethane diisocyanate is (15-25):(5-15).

5. The preparation method according to claim 4, characterized in that, The mass ratio of the hydroxyl-terminated polydimethylsiloxane to the hydroxyl-terminated dimethyldiphenylsiloxane is (5-10):(1-5).

6. The preparation method according to claim 5, characterized in that, The synthesis of the fluorine-modified silica nanoparticles specifically includes: S21. Mix silica nanoparticles with ethanol and disperse them by ultrasonication to form a silica dispersion; S22. Tridecylfluorooctyltriethoxysilane was mixed with ethanol, the pH was adjusted to 3, and the mixture was stirred to prepare a long-chain fluorosilanol hydrolysate. S23. Add silica dispersion to long-chain fluorosilanol hydrolysate, add trifluoropropyltriethoxysilane, stir, centrifuge the reaction solution, collect the precipitate, wash with ethanol, and dry in a vacuum oven to obtain fluorine-modified silica nanoparticles.

7. The preparation method according to claim 6, characterized in that, The mass ratio of the silica nanoparticles to tridecafluorooctyltriethoxysilane and trifluoropropyltriethoxysilane is (15-25):(1-5):(0.5-3).

8. The preparation method according to claim 7, characterized in that, The mass ratio of the fluorine-modified silica nanoparticles to the fluorine-silicone-modified polyurethane polymer solution is 1:(3-10).

9. The preparation method according to claim 8, characterized in that, The hydrophobic coating has a solid content of 8-15%.

10. A highly durable hydrophobic coating obtained by the preparation method according to any one of claims 1-9.

Images