Microwave heating hydrophobic coating as well as preparation method and application thereof

Abstract

The invention discloses a microwave heating hydrophobic coating as well as a preparation method and application thereof. The microwave heating hydrophobic coating comprises the following components in percentage by mass: 55-60% of matrix resin, 10-30% of a microwave absorbent, 8-12% of a hydrophobic modifier, 2-4% of a dispersing agent, 5-7% of a curing agent, 0.1-0.3% of a toughening agent, 0.45-0.6% of an interface modifier and the balance of a solvent, the matrix resin is epoxy modified organic silicon resin; the microwave absorbent is composed of nano SiC particles and nano Fe3O4 (at) SiO2 particles. The microwave heating hydrophobic coating successfully realizes collaborative design of microwave heating and hydrophobic functions, so that electromagnetic waves can be efficiently converted into heat energy to directionally act on an ice layer on the surface of concrete, rapid and low-energy-consumption deicing without damaging a matrix is realized, the hydrophobic capacity, durability and crack resistance of a concrete product can be improved, and the service life of the concrete product is prolonged. The deicing device can be widely applied to the field of surface deicing of concrete products in plateau alpine regions.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of concrete products, in particular to a microwave heating hydrophobic coating and a preparation method and application thereof. BACKGROUND

[0002] In plateau and high-cold regions, concrete products (such as bridge bodies, building components, power transmission tower bases, etc.) are exposed to low temperature, high humidity and strong wind environment for a long time, and the surface thereof is prone to icing. The formation of ice layer not only significantly increases the self weight of the structure, leading to the risk of load overrun, but also may cause the following problems: (1) the difference in expansion coefficient between the ice layer and the concrete easily causes surface erosion, accelerating the material degradation; (2) the accumulation of ice and snow affects the normal use function of the component or causes safety problems (such as the ice layer or ice ridge at the exit of the tunnel falling to cause traffic safety accidents, which must be eliminated in a safe period to eliminate the hidden danger); (3) the traditional mechanical or chemical deicing method is low in efficiency, and may damage the concrete structure or pollute the environment.

[0003] At present, the technologies for deicing the surface of concrete mainly include spreading snow-melting agent, heating by electric heating wire or manual removal. However, these methods have obvious limitations in the application in plateau and high-cold regions: the snow-melting agent is corrosive to concrete, and its efficiency decreases sharply in low temperature environment; the electric heating wire needs to be pre-embedded for construction, and is high in energy consumption and difficult to maintain; manual deicing is low in efficiency, and is difficult to deal with large-area icing. In recent years, microwave heating technology has been explored for deicing roads due to its advantages of non-contact, strong penetration and directional energy transmission, but the existing technologies mainly focus on asphalt pavement or metal substrate, and ordinary concrete has very low microwave absorption efficiency, so it is difficult to directly use microwave energy to achieve rapid ice melting.

[0004] At the same time, the hydrophobic performance, durability and crack resistance of the surface of the concrete product in the prior art are usually not specially designed, and it is difficult to meet the performance requirements for long-term safe service in plateau and high-cold regions.

[0005] Therefore, it is urgent to develop a microwave heating hydrophobic functional coating specially used for concrete products, which can efficiently convert electromagnetic waves into heat energy, and act on the ice layer on the surface of concrete in a directional manner, so as to realize rapid, low-energy and non-damaging deicing of the substrate, and can improve the hydrophobic ability, durability and crack resistance of the concrete product, thereby ensuring the safety and durability of the concrete product in plateau and high-cold regions. SUMMARY

[0006] The purpose of the present application is to provide a microwave heating hydrophobic coating and a preparation method and application thereof, which can efficiently convert electromagnetic waves into heat energy, and act on the ice layer on the surface of concrete in a directional manner, so as to realize rapid, low-energy and non-damaging deicing of the substrate, and can improve the hydrophobic ability, durability and crack resistance of the concrete product.

[0007] Technical solution: The microwave heating hydrophobic coating comprises, based on 100% of the total mass fraction, 55-60% of a base resin, 10-30% of a microwave absorber, 8-12% of a hydrophobic modifier, 2-4% of a dispersing agent, 5-7% of a curing agent, 0.1-0.3% of a toughening agent, 0.45-0.6% of an interface modifier, and the balance of a solvent. The base resin is an epoxy-modified silicone resin. The microwave absorber is composed of nano-SiC particles and Fe3O4@SiO2 particles.

[0008] The microwave heating hydrophobic coating provided by the application can realize microwave heating and hydrophobic deicing functions, and can also improve the durability of concrete products in high-temperature and low-temperature climate conditions in plateau and alpine regions. On the one hand, the polar groups such as -OH and -COOH in the epoxy resin in the coating component form strong hydrogen bonds or chemical bonds with the surface of the concrete, and the siloxane network of the organic silicon fills the microcracks of the concrete and reduces the porosity, and the alkyl side chain of the organic silicon has a "lotus effect" water blocking effect, combined with the strong hydrophobic effect of nano-F-SiO2, so that the coating forms a dense hydrophobic film, blocks the penetration of water and corrosive media such as chloride ions and sulfate ions, delays the corrosion of steel bars, chemical corrosion and freeze-thaw damage, and can effectively improve the impermeability and freeze-thaw cycle resistance of the concrete product. On the other hand, the nano-SiO2 particles have high solar reflectivity, so the microwave heating hydrophobic functional coating provided by the application has a certain radiation refrigeration effect, which helps to reduce the surface temperature of the concrete product under strong sunlight in the plateau during the day, and reduces the formation and development of microcracks on the surface of the concrete product caused by the large temperature difference between day and night in the plateau.

[0009] Further, the epoxy-modified silicone resin has a dynamic viscosity of 800-1000 cP at 25 DEG C and an epoxy value of 0.45-0.55.

[0010] Further, the mass ratio of the nano-SiC particles to the nano-Fe3O4@SiO2 particles in the microwave absorber is (1-3):(1-3).

[0011] The microwave heating hydrophobic coating provided by the application has excellent dielectric loss characteristics for microwaves, and the Fe3O4@SiO2 particles have excellent magnetic loss characteristics for microwaves, so that the impedance matching characteristics of the coating can be significantly improved, microwaves are more easily incident on the coating and are absorbed and converted into heat energy; meanwhile, the nanometer carbon tube and the graphene have electric conduction loss characteristics for microwaves, so that the microwave absorption can be further enhanced, and therefore, the functional coating provided by the application changes the poor microwave response characteristics of the concrete product, so that the microwave heating function of the specific surface layer is generated, local heat is generated under microwave irradiation, and stress separation is generated at the interface between the ice layer and the coating through the difference in the thermal expansion coefficient, or the ice layer at the interface is melted to greatly reduce the adhesion between the ice layer and the surface of the product.

[0012] Further, the nanometer Fe3O4@SiO2 particles are prepared by the following steps: (1) uniformly mixing FeCl3·6H2O, FeSO4·7H2O and deionized water to prepare an iron salt solution for standby; (2) adding deionized water and then adding ammonia water to adjust the pH to 10-12 in a reactor, heating to 70-80℃, and then passing nitrogen, uniformly dropping the iron salt solution under the conditions of stirring and ultrasonic dispersion, continuously reacting for 30-40 minutes after the dropping is completed for 1-2 hours, stopping stirring after the reaction is completed, separating and washing, and then ultrasonic dispersion in anhydrous ethanol to prepare a nanometer Fe3O4 particle ethanol dispersion liquid for standby; (3) mixing the nanometer Fe3O4 particle ethanol dispersion liquid and polyvinylpyrrolidone, then ultrasonic dispersion, then adding ammonia water and anhydrous ethanol, heating to 40-50℃ under nitrogen protection, then dropping tetraethyl orthosilicate, continuously stirring for 6-8 hours, and then washing and drying to prepare the nanometer Fe3O4@SiO2 particles.

[0013] In the microwave heating hydrophobic coating provided by the application, the wave-absorbing component nanometer SiC has high chemical stability, and after the nanometer Fe3O4 is coated with SiO2 to form a Fe3O4@SiO2 core-shell structure, the corrosion failure of the nanometer Fe3O4 under the influence of the alkaline conditions of the concrete and environmental climate factors can be avoided.

[0014] Further, the mass ratio of FeCl3·6H2O and FeSO4·7H2O in the step (1) is (6-8):(3-5); The power of the ultrasonic dispersion in the step (2) is 250-350W; The mass ratio of the nanometer Fe3O4 particle ethanol dispersion liquid, polyvinylpyrrolidone and tetraethyl orthosilicate in the step (3) is (12-15):(3-4):(1-2).

[0015] Further, the hydrophobic modifier is a nanometer fluorinated silicon dioxide particle. The dispersant is a polyether-modified polysiloxane; The curing agent is selected from polyamides with an epoxy equivalent of 200-300; The solvent is selected from at least one of xylene or n-butanol; The toughening agent is selected from at least one of carbon nanotubes or graphene; The interface modifier is selected from at least one of the silane coupling agents KH-550, KH-560, or KH-570.

[0016] Further, the dispersant is BYK-163; the curing agent is polyamide 650 with an epoxy equivalent of 240; the solvent is a mixed solvent of xylene and n-butanol in a volume ratio of 4:1; the toughening agent is a mixed material of carbon nanotubes and graphene in a mass ratio of 1:1; and the interface modifier is silane coupling agent KH-550.

[0017] The microwave-heated hydrophobic coating provided by this invention has nano-fluorinated silica particles (F-SiO2) in the coating components, which have good hydrophobic properties, further reducing the adhesion of ice layers and achieving rapid ice removal when combined with microwave heating.

[0018] The microwave-heatable hydrophobic coating provided by this invention features high-bond-energy organosilicon with high UV irradiation stability. Combined with the rigid structure of epoxy, this slows down the aging of the coating under high-altitude, high-UV environments. Furthermore, carbon nanotubes and graphene in the coating components enhance its toughness and crack resistance. Another aspect of the present invention provides a method for preparing any one of the above-mentioned microwave-heated hydrophobic coatings, comprising the following steps: (1) Surface pretreatment: Clean the surface of the substrate and spray an interface modifier ethanol solution; (2) Coating slurry preparation: Mix microwave absorber, toughening agent and dispersant, interface modifier and solvent in proportion and ball mill, add matrix resin, hydrophobic modifier and curing agent, ultrasonically treat and adjust viscosity to prepare coating slurry; (3) Spraying and curing: Spray the coating slurry onto the substrate surface 1-2 times, and after curing, a microwave-heated hydrophobic coating is formed.

[0019] Furthermore, the viscosity of the coating slurry in step (2) is 30-40 cp; In step (3), the thickness of each film layer during spraying is controlled at 80-100μm, and the curing conditions are dry heat curing at 70-80°C for 1-3 hours or curing at 10-30°C for 48-60 hours.

[0020] Finally, the present invention also provides the application of any of the above-mentioned microwave-heated hydrophobic coatings in the de-icing of concrete products in high-altitude and cold regions.

[0021] Further, the application comprises the following steps: directing the microwave emitting device to the surface of the coating, and emitting microwaves with a frequency of 2.4-2.5 GHz and a power of 500 W-1.5 kW for 30-60 s to complete the deicing of the surface layer of the concrete product.

[0022] The microwave heating hydrophobic coating provided by the application provides an efficient method for deicing the surface layer of prefabricated concrete bridges and other products serving in high-altitude and high-cold regions, and can effectively avoid the damage and destruction of concrete products caused by mechanical planing and spraying of deicing agents, and the like.

[0023] Advantages: (1) The microwave heating hydrophobic coating provided by the application successfully realizes the synergistic design of microwave heating and hydrophobic functions by adding microwave absorbers and hydrophobic modifiers in the base resin and auxiliary addition of other functional components, so that it can efficiently convert electromagnetic waves into heat energy and act on the ice layer of the concrete surface layer in a directional manner, realize rapid, low-energy and non-damaging deicing, and can improve the hydrophobic ability, durability and crack resistance of the concrete product, and can be widely applied in the field of surface layer deicing of concrete products in high-altitude and high-cold regions.

[0024] (2) In the microwave heating hydrophobic coating provided by the application, the nano-SiC in the coating components has excellent dielectric loss characteristics for microwaves, and the Fe3O4@SiO2 particles have excellent magnetic loss characteristics for microwaves, and the combination of the two can significantly improve the impedance matching characteristics of the coating, so that microwaves are more easily incident on the coating and absorbed and converted into heat energy; at the same time, the nano-carbon tube and graphene have electric conduction loss characteristics for microwaves, which can further enhance the absorption of microwaves, therefore, the functional coating provided by the application changes the poor microwave response characteristics of the concrete product, so that it has a specific surface layer microwave heating function, generates local heat under microwave irradiation, and causes stress peeling at the interface between the ice layer and the coating through the difference in the thermal expansion coefficient, or causes the thin layer of ice at the interface to melt, thereby greatly reducing the adhesion between the ice layer and the surface of the product.

[0025] (3) The microwave heating hydrophobic coating provided by the application can realize microwave heating and hydrophobic deicing functions, and can also improve the durability of concrete products under the service of large temperature difference climate conditions in plateau alpine regions. On the one hand, the polar groups such as -OH and -COOH in the epoxy resin in the coating component form strong hydrogen bonds or chemical bonds with the surface of the concrete, and the siloxane network of the organic silicon fills the microcracks of the concrete and reduces the porosity, and the alkyl side chain of the organic silicon has a "lotus leaf effect" water blocking effect, combined with the strong hydrophobic effect of nano F-SiO2, so that the coating forms a dense hydrophobic film, blocks the penetration of water and corrosive media such as chloride ions and sulfate, delays the corrosion of steel bars, chemical corrosion and freeze-thaw damage, and can effectively improve the impermeability and freeze-thaw cycle resistance of the concrete product; on the other hand, the nano SiO2 particles have high solar reflectivity, so the microwave heating and hydrophobic functional coating provided by the application has a certain radiation refrigeration effect, which helps to reduce the surface temperature of the concrete product under strong sunlight in the plateau during the day, and reduces the formation and development of surface microcracks of the concrete product caused by the large temperature difference between day and night in the plateau.

[0026] (4) The microwave heating and hydrophobic coating provided by the application has good durability in the harsh service environment of the plateau alpine region, and can continuously and stably play the functions of microwave heating, hydrophobicity and protection of the concrete product. The high-energy organic silicon in the coating has high ultraviolet radiation stability, and after being combined with the rigid structure of the epoxy, the aging of the coating in the strong ultraviolet environment of the plateau can be slowed down; the carbon nanotubes and graphene in the coating component enhance the toughness and crack resistance of the coating itself; the wave-absorbing component nano SiC has high chemical stability, and after the nano Fe3O4 is coated with SiO2 to form a Fe3O4@SiO2 core-shell structure, the corrosion failure of the nano Fe3O4 under the influence of the alkaline conditions of the concrete and environmental factors can be avoided.

[0027] (5) The microwave heating and hydrophobic coating provided by the application provides an efficient method for deicing the surface of precast concrete bridges and other products serving in the plateau alpine region, which can effectively avoid the damage and destruction of the concrete product caused by mechanical removal, spraying of deicing agents and the like, and the application technology can be applied to deicing of wind power tower drums and other application scenarios. DETAILED DESCRIPTION

[0028] The application will be described below in conjunction with specific embodiments. It should be noted that the following examples are examples of the application and are only used to illustrate the application, but not to limit the application. Other combinations and various modifications within the concept of the application can be made without departing from the spirit or scope of the application.

[0029] The epoxy-modified silicone resin is an organic silicone resin HY-3074 purchased from Shanghai Huilian New Material Co., Ltd.; the remaining reagents and equipment are conventional reagents and equipment in the technical field.

[0030] Preparation of nano Fe3O4@SiO2 particles: The nano Fe3O4@SiO2 particles are prepared by the following steps: (1) Dissolve 14 parts of FeCl3·6H2O and 8 parts of FeSO4·7H2O in 100 parts of deionized water to prepare an iron salt solution; (2) Add 50 parts of deionized water to a reactor, and adjust the pH value to 11 by adding an appropriate amount of ammonia water, and then heat to 80°C and continuously pass nitrogen; (3) Use a peristaltic pump to add the iron salt solution to the reactor within 2h, continuously stir and perform ultrasonic dispersion at a power of 300W during the process; continue to react for 30min after the iron salt solution is completely added; (4) After stopping stirring, perform solid-liquid separation in a magnetic field, and then wash the separated nano Fe3O4 particles with deionized water and anhydrous ethanol alternately for 4 times, and then ultrasonic dispersion in 50 parts of anhydrous ethanol; (5) Mix the above nano Fe3O4 particle ethanol dispersion with 6 parts of polyvinylpyrrolidone, ultrasonic dispersion for 30min, then add 5 parts of ammonia water and 50 parts of anhydrous ethanol, heat to 40°C under N2 atmosphere, then slowly drop 2 parts of tetraethyl orthosilicate within 4min, react for 6h under continuous stirring, finally wash with anhydrous ethanol for 3 times, and vacuum dry at 60°C to prepare the nano Fe3O4@SiO2 particles.

[0031] Example 1 A microwave heating hydrophobic coating, according to the mass ratio, includes the following components: epoxy modified silicone resin 58%, nano SiC particles 10%, nano Fe3O4@SiO2 particles 10%, nano F-SiO2 particles 10%, BYK-163 3%, polyamide 650 5.3%, xylene / n-butanol (4:1 mixture) 3%, carbon nanotubes 0.1%, graphene 0.1%, KH-550 silane coupling agent 0.5%.

[0032] The preparation method of the above microwave heating hydrophobic coating includes the following steps: (1) Concrete product surface pretreatment: clean and dry the surface of the concrete product with compressed air, then spray 1% KH-550 ethanol solution at 150g / m 2 Dose twice, with an interval of 5h; (2) Coating slurry preparation: mix nano SiC, Fe3O4@SiO2 particles, carbon nanotubes, graphene, BYK-163, and xylene according to the formula ratio, ball mill for 2h at a speed of 300rpm, then add KH-550 and continue to ball mill for 30min to obtain a suspension dispersion; (3) Mix the epoxy-modified silicone resin with the suspension dispersion under N2 atmosphere, treat with 300W ultrasonic for 30min, then slowly add the F-SiO2 ethanol dispersion (F-SiO2 is dispersed in anhydrous ethanol at 10wt% in advance), and continue stirring for 1h; (4) Add polyamide 650 and stir for 10min to remove bubbles, and adjust the final viscosity of the slurry to 35cP to ensure the construction performance; (5) Spraying and curing: use compressed air spray gun to spray the slurry evenly on the surface of the pretreated concrete product in two passes, the average thickness of the first pass is about 80μm, and the second pass is carried out after the surface of the coating layer of the first pass is dry, the average thickness is 90μm, and then cured at room temperature for 60h to obtain a microwave heating hydrophobic coating.

[0033] Example 2 A microwave heating hydrophobic coating, according to the mass ratio, comprises the following components: epoxy-modified silicone resin 55%, nano-SiC particles 5%, nano-Fe3O4@SiO2 particles 15%, nano-F-SiO2 particles 12%, BYK-163 3.5%, polyamide 650 5%, xylene / n-butanol (4:1 mixture) 3.85%, carbon nanotubes 0.08%, graphene 0.12%, KH-550 silane coupling agent 0.45%.

[0034] The preparation method of the above microwave heating hydrophobic coating, comprising the following steps: (1) Surface pretreatment of concrete product: clean and dry the surface of the concrete product with compressed air, then use 1% KH-550 ethanol solution at 100g / m 2 Spray twice at a dose, with an interval of 3.5h; (2) Preparation of coating slurry: mix nano-SiC, Fe3O4@SiO2 particles, carbon nanotubes, graphene with BYK-163 and xylene according to the formula ratio, ball mill at 350rpm for 1.5h, then add KH-550 and continue ball milling for 25min to obtain a suspension dispersion; (3) Mix the epoxy-modified silicone resin with the suspension dispersion under N2 atmosphere, treat with 450W ultrasonic for 20min, then slowly add the F-SiO2 ethanol dispersion (F-SiO2 is dispersed in anhydrous ethanol at 10wt% in advance), and continue stirring for 1h; (4) Add polyamide 650 and stir for 12min to remove bubbles, and adjust the final viscosity of the slurry to 40cP to ensure the construction performance; (5) Spraying and curing: the slurry is evenly sprayed twice on the surface of the pretreated concrete product using a compressed air spray gun, the average thickness of the first spraying is about 50 μm, the second spraying is performed after the coating layer of the first spraying is surface dried, the average thickness is 100 μm, and then the microwave heating hydrophobic coating is obtained after curing at room temperature for 48 h.

[0035] Example 3 A microwave heating hydrophobic coating, including the following components in terms of mass ratio: epoxy modified silicone resin 60%, nano-SiC particles 15%, nano-Fe3O4@SiO2 particles 5%, nano-F-SiO2 particles 8%, BYK-163 2%, polyamide 650 6%, xylene / n-butanol (4:1 mixture) 3.2%, carbon nanotubes 0.15%, graphene 0.05%, and KH-550 silane coupling agent 0.6%.

[0036] The preparation method of the microwave heating hydrophobic coating described above, including the following steps: (1) Surface pretreatment of the concrete product: the surface of the concrete product is cleaned and dried using compressed air, and then the surface is treated with 1% KH-550 ethanol solution at 200 g / m 2 The dosage is sprayed twice, and the second spraying is performed after 6 h; (2) Preparation of the coating slurry: the nano-SiC, Fe3O4@SiO2 particles, carbon nanotubes, graphene, BYK-163, and xylene are mixed in the formula ratio, ball milled at 250 rpm for 3 h, and then the KH-550 is added and ball milled for 15 min to obtain a suspension dispersion; (3) Under the protection of N2 atmosphere, the epoxy modified silicone resin is mixed with the suspension dispersion, ultrasonically treated at 500 W for 10 min, and then the F-SiO2 ethanol dispersion (F-SiO2 is previously dispersed in anhydrous ethanol at 10 wt%) is slowly added, and continuous stirring is performed for 45 min; (4) The polyamide 650 is added and stirred for 8 min to remove air bubbles, and the final viscosity of the slurry is adjusted to 30 cP to ensure the construction performance; (5) Spraying and curing: the slurry is evenly sprayed twice on the surface of the pretreated concrete product using a compressed air spray gun, the average thickness of the first spraying is about 50 μm, the second spraying is performed after the coating layer of the first spraying is surface dried, the average thickness is 50 μm, and then the microwave heating hydrophobic coating is obtained after curing at 80°C under dry heat conditions for 2 h.

[0037] Comparative Example 1 The basic process is the same as that of Example 1, except that the nano-SiC particles and the nano-Fe3O4@SiO2 particles are replaced by other components in equal amounts, and the mass ratio relationship between the other components remains unchanged.

[0038] Comparative Example 2 The same as Example 1, except that the nano Fe3O4 particles were not coated with SiO2.

[0039] Comparative Example 3 The same as Example 1, except that the nano Fe3O4 particles were not coated with SiO2.

[0040] Comparative Example 4 The same as Example 1, except that the carbon nanotube and graphene components were not added.

[0041] Performance Test Deicing ability test: The microwave heating deicing ability of the products of Examples 1-3 and Comparative Example 1 was tested by the following steps: (1) Application scenario: The outer side wall of a prefabricated concrete box girder of a highland railway bridge was used as the substrate, and the products of Examples 1-3 and Comparative Example 1 were sprayed and cured; the environmental temperature in winter was -15°C, and the outer side wall of the box girder was attached with an ice layer with an average thickness of 13.2 mm; (2) The microwave emission device was installed on the mechanical long arm of the microwave deicing trolley, with the microwave emission port facing the outer side wall of the prefabricated concrete box girder, moving at a speed of 0.5 m / s, and emitting microwaves with a fixed frequency of 2.45 GHz at a power of 1.5 kW; the process was repeated multiple times, so that each part of the outer side wall of the prefabricated concrete box girder sprayed with the microwave heating hydrophobic coating was irradiated with microwaves for a total of 60 s; (3) The coating heated under the action of microwave irradiation, and the average temperature at the interface between the coating and the attached ice layer and the area of the ice layer on the outer side wall of the box girder that spontaneously fell off were detected using embedded temperature sensors.

[0042] The test results are shown in the following table: Average temperature (°C) Peeling area (%) Example 1 5.5 82 Example 2 8.5 73 Example 3 3.7 100 Comparative Example 1 -9.3 0 According to the comparison of the test results, the nano SiC particles and the nano Fe3O4@SiO2 particles play an important role in the process of converting microwave energy into heat energy as wave absorbers in the present application. Without these two components, the prepared coating will not have a significant microwave heating deicing effect.

[0043] Stability test: The products of Example 1 and Comparative Example 2 were tested for microwave heating deicing under the same conditions, with an environmental temperature of -13.5°C, an average thickness of the attached ice layer of 10.8 mm, and a microwave heating regime identical to that of the deicing ability test.

[0044] The results show that the product of Example 1 still has a significant deicing effect after 1 year of natural environmental exposure, the average temperature at the interface between the coating and the attached ice layer is 7.2℃, a thin layer of ice at the interface is melted by heat, 79% of the ice layer falls off under the action of gravity, and a small part of the ice layer that does not fall off can be removed by the mechanical arm shovel of the microwave deicing platform car.

[0045] Therefore, the SiO2coating treatment plays an important role in protecting the nano Fe3O4particles in the coating and maintaining the excellent microwave absorption and energy conversion characteristics of the coating.

[0046] Deterioration performance detection: The chloride ion diffusion coefficient of the product of Example 1 and the blank control group is detected by the RCM method, and the specific method is as follows: (1) Core samples are drilled from the side wall of the prefabricated concrete box girder and cut into concrete test pieces of a specified size, part of the test pieces are kept as they are and marked as the blank group, and part of the test pieces are prepared according to the method of Example 1 and the outer surface of the test pieces is sprayed with a microwave heating hydrophobic coating; (2) The RCM method is used to detect the chloride ion diffusion coefficient of the blank group and the product of Example 1, and the results show that the chloride ion diffusion coefficient of the product of Example 1 with a coating is 1.1X10 -12 m 2 / s, and the chloride ion diffusion coefficient of the blank group without spraying is 2.6X10 -12 m 2 / s, which is significantly higher than the former.

[0047] Hydrophobicity detection: The water contact angle of the product of Example 1 and the product of Comparative Example 3 and the blank control group is detected according to the ASTM D7334 standard, and the specific method is as follows: Core samples are drilled from the side wall of the box girder without spraying and marked as the blank group, and core samples are drilled from the part sprayed with the coating of Example 1, the original outer surface of the two test pieces is cleaned with a compressed air gun, and the hydrophobicity test is carried out according to the ASTM D7334 standard, and the results show that the water contact angle of the blank group is 42°, and the water contact angle of the coating of Example 1 is 121°, indicating that the coating provided by the present application has a significant hydrophobic property.

[0048] According to the above water contact angle detection method, the product of Example 1 is replaced by the product of Comparative Example 3 for detection, and the water contact angle of the coating surface is 93°, and the hydrophobic property is still better than that of the blank group without coating treatment in Example 1, but is weaker than that of the product of Example 1 containing nano F-SiO2particles.

[0049] Therefore, the nano SiO2particles treated by fluorination play an important role in improving the hydrophobic property of the coating.

[0050] Anti-cracking ability test: after the products of Example 1 and Comparative Example 4 were exposed to the natural environment for one year and experienced 10 microwave heating deicing cycles (microwave heating regime same as Example 1), a small amount of visible fine cracks appeared in the coating of the product of Comparative Example 4, which was rated as level 2 according to ISO 4628-4:2016, while the coating of the product of Example 1 only had a very small amount of fine cracks that needed to be observed under magnification, which was rated as level 0.

[0051] Therefore, it can be seen that the carbon nanotube and graphene components play an important role in improving the anti-cracking performance of the microwave heating hydrophobic coating.

[0052] The above embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application should be covered within the protection scope of the present application.

Claims

1. A microwave-heatable hydrophobic coating, characterized in that, The microwave heating hydrophobic coating comprises, based on 100% total mass fraction, 55-60% base resin, 10-30% microwave absorber, 8-12% hydrophobic modifier, 2-4% dispersant, 5-7% curing agent, 0.1-0.3% toughening agent, 0.45-0.6% interface modifier, and the balance solvent; The base resin is an epoxy-modified silicone resin; The microwave absorber is composed of nano-SiC particles and nano-Fe3O4@SiO2 particles.

2. The microwave-heatable hydrophobic coating according to claim 1, characterized in that The epoxy-modified silicone resin has a dynamic viscosity of 800-1000 cP at 25℃ and an epoxy value of 0.45-0.

55.

3. The microwave-heatable hydrophobic coating according to claim 1, characterized in that The mass ratio of the nano-SiC particles to the nano-Fe3O4@SiO2 particles in the microwave absorber is (1-3):(1-3).

4. The microwave-heatable hydrophobic coating according to claim 1, characterized in that The nano-Fe3O4@SiO2 particles are prepared by the following steps: (1) uniformly mixing FeCl3·6H2O, FeSO4·7H2O and deionized water to prepare an iron salt solution for standby; (2) in a reactor, adding deionized water, then adding ammonia water to adjust the pH to 10-12, heating to 70-80℃, then bubbling nitrogen, uniformly dropping the iron salt solution under the conditions of stirring and ultrasonic dispersion, dropping for 1-2 hours, then continuing to react for 30-40 minutes, stopping stirring after the reaction is completed, separating and washing, then ultrasonic dispersion in anhydrous ethanol to prepare a nano-Fe3O4 particle ethanol dispersion solution for standby; (3) mixing the nano-Fe3O4 particle ethanol dispersion solution with polyvinylpyrrolidone, then ultrasonic dispersion, then adding ammonia water and anhydrous ethanol, heating to 40-50℃ under nitrogen protection, then dropping tetraethyl orthosilicate, continuously stirring for 6-8 hours, then washing and drying to obtain the nano-Fe3O4@SiO2 particles.

5. The microwave-heatable hydrophobic coating according to claim 4, characterized in that The mass ratio of FeCl3·6H2O to FeSO4·7H2O in step (1) is (6-8):(3-5); The ultrasonic dispersion power in step (2) is 250-350 W; The mass ratio of the nano-Fe3O4 particle ethanol dispersion solution, polyvinylpyrrolidone and tetraethyl orthosilicate in step (3) is (12-15):(3-4):(1-2).

6. The microwave-heatable hydrophobic coating according to claim 1, characterized in that The hydrophobic modifier is nano-fluorinated silicon dioxide particles; The dispersant is polyether-modified polysiloxane; The curing agent is selected from polyamide with an epoxy equivalent of 200-300; The solvent is selected from at least one of xylene or n-butanol; The toughening agent is selected from at least one of carbon nanotubes or graphene; The interface modifier is selected from at least one of silane coupling agents KH-550, KH-560 or KH-570.

7. The method for preparing a hydrophobic coating which is microwave-heatable according to any one of claims 1 to 6, characterized in that The method comprises the following steps: (1) surface pretreatment: cleaning the surface of the substrate and spraying an interface modifier ethanol solution; (2) coating slurry preparation: mixing the microwave absorber, toughening agent, dispersant, interface modifier and solvent in proportion, ball milling, adding the base resin, hydrophobic modifier and curing agent, ultrasonic treatment and adjusting the viscosity to prepare a coating slurry; (3) spraying and curing: spraying the coating slurry on the surface of the substrate 1-2 times, then curing to form a microwave heating hydrophobic coating.

8. The method of claim 7, wherein the microwave heating is performed at a temperature of 50 to 150°C. The viscosity of the coating slurry in step (2) is 30-40 cp; In step (3), the thickness of each layer is controlled at 80-100 μm, and the curing conditions are 70-80 ℃ dry heat curing for 1-3 h or 10-30 ℃ curing for 48-60 h.

9. The use of the microwave heating hydrophobic coating according to any one of claims 1-6 in the deicing of the surface layer of concrete products in high-altitude cold regions.

10. Use according to claim 9, characterized in that, The method comprises the following steps: The microwave emission device is directed to the surface of the coating, and the deicing of the surface layer of the concrete product is completed after 30-60 s of microwave emission at a frequency of 2.4-2.5 GHz and a power of 500 W-1.5 kW.