Preparation method of water vapor-resistant polyurethane coating

Abstract

The invention relates to a preparation method of a water vapor resistant polyurethane coating, and relates to the technical field of polyurethane coating compositions. The preparation method comprises the following steps: (1) uniformly mixing hydroxyl vinyl ether, a filler, four-arm-polyethylene glycol-hydroxyl (4arm-PEG-OH), an auxiliary agent and a solvent to obtain a component A; (2) mixing isocyanate and a catalyst to obtain a component B; and (3) forming the polyurethane coating by the component A and the component B, the filler comprises nano silicon dioxide, nano talcum powder and / or nano montmorillonite. The prepared polyurethane coating can form a four-dimensional network through a curing cross-linking reaction of hydroxyl of 4arm-PEG-OH and isocyanate, the four-dimensional network is filled with a micro-nano-level hydrophobic filler, a low-surface-energy interface is constructed on the surface of the coating, the heat conduction efficiency is remarkably reduced, heat exchange in the condensation process can be synergistically inhibited, and the thermal conductivity of the coating is improved. Therefore, excellent water vapor resistance is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of polyurethane coating compositions, and in particular to a method for preparing a water vapor-resistant polyurethane coating. Background Art

[0002] Polyurethane waterproof coatings have been widely used in various industrial scenarios and have performed well. For example, some polyurethane waterproof coatings used to coat hot wastewater storage tanks and insulated pipes can withstand immersion in 60°C hot water without blistering or peeling. However, when encountering more severe working conditions—for example, when water vapor with a temperature above 100°C comes into contact with a coating with a temperature below the water vapor dew point, the water vapor will quickly liquefy and release a large amount of latent heat of vaporization. The polyurethane waterproof coating that absorbs a large amount of heat is more likely to cause the distance between the polymer chain segments to increase, causing swelling, the coating volume to expand, and the density to decrease, making its actual service life far lower than the design value. Summary of the Invention

[0003] The purpose of the present invention is to disclose a method for preparing a water vapor resistant polyurethane coating to solve one or more technical problems existing in the prior art and provide at least one beneficial option or create conditions.

[0004] The first aspect of the present invention is to provide a method for preparing a water vapor resistant polyurethane coating.

[0005] The preparation method according to the first aspect of the present invention comprises the following steps: (1) Mixing hydroxy vinyl ether, filler, four-arm-polyethylene glycol-hydroxyl (4arm-PEG-OH), additives, and solvent to obtain component A; (2) mixing isocyanate and catalyst to obtain component B; (3) Component A and component B constitute the polyurethane coating; The filler includes nano silicon dioxide, nano talc and / or nano montmorillonite.

[0006] 4arm-PEG-OH is a functional polymer that combines a star-shaped topological structure with multi-reactive hydroxyl groups. Compared with linear PEG, 4arm-PEG-OH has higher steric hindrance and lower solution viscosity. When the hydroxyl groups of 4arm-PEG-OH react with isocyanate to form a four-dimensional network, the cross-linking density is very high, which can greatly improve the tensile strength. At the same time, nano-silica, nano-talc and nano-montmorillonite are all hydrophobic, so the filler evenly dispersed in component A can fill the pores of the four-dimensional network formed by cross-linking, further improving the density and making it difficult for water vapor to penetrate into the coating.

[0007] At the same time, the polyurethane coating provided by the present invention abandons the silane coupling agent, avoiding the reaction of the amino (-NH2) or epoxy group of the silane coupling agent with the isocyanate (-NCO) in the polyurethane prepolymer, resulting in a reduction in the -NCO groups available for the main reaction and affecting the cross-linking density of the coating.

[0008] The obtained polyurethane coating presents a highly dense cross-linked network structure after curing. Under the synergistic modification of high-mesh hydrophobic fillers, a composite protective system with both physical barrier and heat conduction inhibition functions is formed. Specifically: (I) Nano-scale hydrophobic fillers are evenly dispersed, creating a low surface energy interface on the coating surface, significantly improving the ability to repel water vapor and effectively inhibiting its penetration and intrusion; (II) The low thermal conductivity of the filler itself and the micro-nanoscale thermal insulation pore network formed in the coating can significantly reduce the efficiency of heat conduction and block the transfer path of latent heat from condensation of water vapor to the interior of the coating; (III) The above synergistic effect enables the coating to resist the physical penetration of water vapor while inhibiting the heat exchange during the condensation process, ultimately giving the polyurethane coating excellent resistance to water vapor erosion and anti-condensation latent heat transfer properties.

[0009] Through material interface design and microstructure regulation, this system has achieved a functional upgrade from "physical barrier" to "synergistic inhibition of heat and mass transfer", providing a new technical path for the design of protective coatings that need to periodically face water vapor working environments.

[0010] In a further application embodiment, the degree of polymerization of the 4arm-PEG-OH is 20~40kDa; preferably, the degree of polymerization of the 4arm-PEG-OH is 25~38kDa; more preferably, the degree of polymerization of the 4arm-PEG-OH is 30~35kDa.

[0011] In a further embodiment, the hydroxy vinyl ether includes 4-hydroxybutyl vinyl ether and / or triethylene glycol divinyl ether.

[0012] In further application embodiments, the isocyanate includes at least one of hydrogenated phenylmethane diisocyanate (hydrogenated MDI), toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), and hexamethylene diisocyanate (HDI). Hydrogenated phenylmethane diisocyanate, toluene diisocyanate (TDI), and diphenylmethane diisocyanate (MDI) are further preferred. Using a benzene ring-containing isocyanate for crosslinking and curing helps improve the density of the coating. Hydrogenated phenylmethane diisocyanate also imparts improved yellowing resistance to the coating.

[0013] In a further embodiment of the present invention, the catalyst comprises an organic tin, such as dibutyltin dilaurate, di(dodecylthio)dibutyltin.

[0014] In a further application embodiment, the auxiliary agent includes at least one of a defoaming agent, sodium lauryl sulfate, and nonylphenol polyethylene glycol.

[0015] In a further application embodiment, the defoaming agent is polydimethylsiloxane.

[0016] In a further embodiment, the solvent includes ethanol and water. For example, the solvent is composed of ethanol and water in a mass ratio of 1:(0.5-3).

[0017] In a further application embodiment, the mass ratio of the hydroxy vinyl ether, filler, and 4arm-PEG-OH is 1:(0.5~1.5):(1~3); preferably, the mass ratio of the three is 1:(0.8~1.4):(1.5~2).

[0018] In a further application embodiment, the mass ratio of the hydroxy vinyl ether to the auxiliary agent and the solvent is 1:(1-5):(8-50); preferably, the mass ratio of the three is 1:(2-5):(10-40).

[0019] In a further application embodiment, in the component B, the mass ratio of isocyanate to catalyst is 1:(0.1-0.5); preferably, the mass ratio of isocyanate to catalyst is 1:(0.1-0.3).

[0020] In a further application embodiment, the mass ratio of component A to component B is 10:(0.1-2); preferably, the further mass ratio is 10:(0.5-1.8).

[0021] In a further application embodiment, the specific steps of the preparation method include: (1) uniformly mixing hydroxy vinyl ether, filler, 4arm-PEG-OH, additives, and solvent to obtain component A, wherein the mass ratio of hydroxy vinyl ether, filler, and 4arm-PEG-OH is 1:(0.5-1.5):(1-3); (2) Mixing isocyanate and catalyst to obtain component B, wherein the mass ratio of isocyanate to catalyst is 1:(0.1~0.5); (3) The component A and the component B constitute the polyurethane coating, and the mass ratio of the component A to the component B is 10:(0.1~2); The filler includes nano silicon dioxide, nano talc and / or nano montmorillonite.

[0022] When the water vapor resistant polyurethane coating prepared by the above preparation method is used, component A and component B are mixed and then cured to obtain a polyurethane coating.

[0023] Preferably, the curing temperature is 40-100° C., and the curing time is 60-150 minutes; more preferably, the curing temperature is 50-90° C., and the curing time is 70-120 minutes.

[0024] Compared with the prior art, the present invention has the following beneficial effects: The polyurethane coating described herein is a two-component coating comprising component A, a hydroxy vinyl ether, a filler, 4arm-PEG-OH, an additive, and a solvent, and component B, an isocyanate, and a catalyst. During use, components A and B are mixed and cured to form a polyurethane coating. The curing and cross-linking reaction between the hydroxyl groups of the 4arm-PEG-OH and the isocyanate forms a four-dimensional network. This network is then filled with micro-nanoscale hydrophobic fillers, creating a low-surface-energy interface on the coating surface. This significantly reduces heat conduction efficiency and synergistically inhibits heat exchange during condensation, resulting in excellent water vapor resistance. DETAILED DESCRIPTION

[0025] In the description of the present invention, if there is a description of first, second, etc., it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0026] The terms "preferably," "more preferably," and the like, used herein refer to embodiments of the present invention that may provide certain benefits under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the present invention.

[0027] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein are understood to include any and all subranges subsumed therein.

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of the present invention.

[0029] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0030] Example 1: Preparation of polyurethane coating No. 1 The preparation method comprises the following steps: (1) By weight, 10 parts of 4-hydroxybutyl vinyl ether, 6 parts of nano-talc, 6 parts of nano-silica, 18 parts of 4-arm-PEG-OH with a degree of polymerization of about 30 kDa, 10 parts of polydimethylsiloxane and 10 parts of sodium lauryl sulfate were added to 200 parts of 55% ethanol solution, and the stirring speed during mixing was 1000 rpm. The stirring was continued for 20 minutes to obtain component A; (2) Mix 22.3 parts of MDI and 4.45 parts of dibutyltin dilaurate at a stirring speed of 200 rpm for 10 minutes to obtain component B; (3) Component A and component B constitute polyurethane coating with a mass ratio of 10:1.03.

[0031] Example 2: Preparation of polyurethane coating No. 2 The preparation method comprises the following steps: (1) By weight, 10 parts of triethylene glycol divinyl ether, 7 parts of nano-montmorillonite, 15 parts of 4-arm-PEG-OH with a degree of polymerization of about 20 kDa, 9 parts of polydimethylsiloxane, and 9 parts of sodium lauryl sulfate were added to 250 parts of a 60% ethanol solution, and the stirring speed during mixing was 800 rpm. The stirring was continued for 30 minutes to obtain component A; (2) Mix 22.3 parts of MDI and 4.45 parts of dibutyltin dilaurate at a stirring speed of 200 rpm for 10 minutes to obtain component B; (3) Component A and component B constitute polyurethane coating with a mass ratio of 10:0.89.

[0032] Example 3: Preparation of polyurethane coating No. 3 The preparation method comprises the following steps: (1) By weight, 10 parts of 4-hydroxybutyl vinyl ether, 14 parts of nanosilica, 20 parts of 4arm-PEG-OH with a degree of polymerization of about 40 kDa, 6 parts of polydimethylsiloxane, and 14 parts of sodium lauryl sulfate were added to 300 parts of a 50% ethanol solution, and the stirring speed during mixing was 1000 rpm. The stirring was continued for 30 minutes to obtain component A; (2) 38.5 parts of TDI and 3.85 parts of dibutyltin dilaurate were mixed at a stirring speed of 200 rpm for 10 minutes to obtain component B; (3) Component A and component B constitute polyurethane coating with a mass ratio of 10:1.16.

[0033] Example 4: Preparation of Polyurethane Coating No. 4 The preparation method comprises the following steps: (1) By weight, 5 parts of 4-hydroxybutyl vinyl ether, 5 parts of triethylene glycol divinyl ether, 12 parts of nano-montmorillonite, 13 parts of 4arm-PEG-OH with a degree of polymerization of about 35 kDa, 10 parts of polydimethylsiloxane and 8 parts of sodium lauryl sulfate were added to 220 parts of 55% ethanol solution, and the stirring speed during mixing was 700 rpm. The stirring was continued for 30 minutes to obtain component A; (2) Mix 23.5 parts of hydrogenated MDI and 3.53 parts of dibutyltin dilaurate at a stirring speed of 200 rpm for 10 minutes to obtain component B; (3) Component A and component B constitute polyurethane coating with a mass ratio of 10:0.99.

[0034] Comparative Example 1: Preparation of Control Polyurethane Coating No. 1 The prior art has produced a polyurethane waterproof coating that can withstand immersion in hot water at 60°C without blistering or peeling. A water-resistant polyurethane coating was prepared according to the disclosed technical solution for comparison experiments with the water vapor-resistant polyurethane coating of the present invention.

[0035] The preparation method comprises the following steps: (1) 4-Hydroxybutyl vinyl ether, complex alcohol, silane coupling agent KH570, polyether triol and hydroxymethyl cellulose were mixed at a stirring speed of 800 rpm for 30 minutes, and then filler (filler composed of nano-silicon dioxide and nano-calcium silicate in a mass ratio of 1:2), terminal hydroxyl polybutadiene, auxiliary agent (auxiliary agent composed of polydimethylsiloxane and sodium lauryl sulfate in a mass ratio of 1:1), and solvent (ethanol and water in a mass ratio of 1:0.8) were added and mixed at a stirring speed of 1000 rpm for 20 minutes to obtain component A; The mass ratio of 4-hydroxybutyl vinyl ether, complex alcohol, silane coupling agent, filler, and hydroxy-terminated polybutadiene is 1:0.8:2:1.5:1; the mass ratio of 4-hydroxybutyl vinyl ether to additives and solvent is 1:2:20; The complex alcohol is composed of the following components, calculated by weight: 1 part of glycerol, 3 parts of xylitol, 2 parts of sorbitol, and 3 parts of pentaerythritol; The mass ratio of 4-hydroxybutyl vinyl ether to polyether triol and hydroxymethyl cellulose is 1:0.3:0.4; (2) Mix isocyanate (TDI) and catalyst (dibutyltin dilaurate) at a stirring speed of 200 rpm for 10 minutes to obtain component B. The mass ratio of isocyanate to catalyst is 1:0.1; (3) Component A and component B constitute a polyurethane coating, and the mass ratio of component A to component B is 10:0.8.

[0036] The difference between Comparative Example 1 and Example 1 is that: Ⅰ. Example 1 does not use specific polyols and terminal hydroxyl polybutadiene, but instead undergoes a nucleophilic addition reaction between the hydroxyl group provided by 4arm-PEG-OH and the isocyanate group; Ⅱ. The total proportion of the filler used in Example 1 in component A is approximately 4.62%, and is limited to nano-talc and nano-silica, and the total proportion of the filler used in Comparative Example 1 in component A is approximately 5.30%, and is limited to nano-silica and nano-calcium silicate; Ⅲ. Example 1 does not use silane coupling agent KH570 and hydroxymethyl cellulose.

[0037] Comparative Example 2: Preparation of Control Polyurethane Coating No. 2 Compared with Example 1, the only difference in Comparative Example 2 is that an equal amount of pentaerythritol is used to replace 4arm-PEG-OH in Example 1, and the rest of the process is the same as Example 1.

[0038] The preparation method comprises the following steps: (1) By weight, 10 parts of 4-hydroxybutyl vinyl ether, 6 parts of nano-talc, 6 parts of nano-silica, 18 parts of pentaerythritol, 10 parts of polydimethylsiloxane and 10 parts of sodium lauryl sulfate were added to 200 parts of 55% ethanol solution, and the stirring speed during mixing was 1000 rpm. The stirring was continued for 20 minutes to obtain component A; (2) Mix 22.3 parts of MDI and 4.45 parts of dibutyltin dilaurate at a stirring speed of 200 rpm for 10 minutes to obtain component B; (3) Component A and component B constitute polyurethane coating.

[0039] Comparative Example 3: Preparation of Control Polyurethane Coating No. 3 Compared with Example 1, the only difference in Comparative Example 3 is that the polymerization degree of the 4arm-PEG-OH used is about 15 kDa, and the rest of the process is the same as that of Example 1.

[0040] The preparation method comprises the following steps: (1) By weight, 10 parts of 4-hydroxybutyl vinyl ether, 6 parts of nano-talc, 6 parts of nano-silica, 18 parts of 4-arm-PEG-OH with a degree of polymerization of about 15 kDa, 10 parts of polydimethylsiloxane and 10 parts of sodium lauryl sulfate were added to 200 parts of 55% ethanol solution, and the stirring speed during mixing was 1000 rpm. The stirring was continued for 20 minutes to obtain component A; (2) Mix 22.3 parts of MDI and 4.45 parts of dibutyltin dilaurate at a stirring speed of 200 rpm for 10 minutes to obtain component B; (3) Component A and component B constitute polyurethane coating.

[0041] Comparative Example 4: Preparation of No. 4 Control Polyurethane Coating Compared with Example 1, the only difference in Comparative Example 4 is that the polymerization degree of the 4arm-PEG-OH used is about 60 kDa, and the rest of the process is the same as Example 1.

[0042] The preparation method comprises the following steps: (1) By weight, 10 parts of 4-hydroxybutyl vinyl ether, 6 parts of nano-talc, 6 parts of nano-silica, 18 parts of 4arm-PEG-OH with a degree of polymerization of about 60 kDa, 10 parts of polydimethylsiloxane and 10 parts of sodium lauryl sulfate were added to 200 parts of 55% ethanol solution, and the stirring speed during mixing was 1000 rpm. The stirring was continued for 20 minutes to obtain component A; (2) Mix 22.3 parts of MDI and 4.45 parts of dibutyltin dilaurate at a stirring speed of 200 rpm for 10 minutes to obtain component B; (3) Component A and component B constitute polyurethane coating.

[0043] Comparative Example 5: Preparation of Control Polyurethane Coating No. 5 Compared with Example 1, the difference of Comparative Example 5 is that silane coupling agent KH570 is added on the basis of Example 1, and the rest of the process is the same as Example 1.

[0044] The preparation method comprises the following steps: (1) By weight, 10 parts of 4-hydroxybutyl vinyl ether, 6 parts of nano-talc, 6 parts of nano-silica, 18 parts of 4arm-PEG-OH, 20 parts of silane coupling agent KH570, 10 parts of polydimethylsiloxane and 10 parts of sodium lauryl sulfate were added to 200 parts of 55% ethanol solution, and the stirring speed during mixing was 1000 rpm. The stirring was continued for 20 minutes to obtain component A; (2) Mix 22.3 parts of MDI and 4.45 parts of dibutyltin dilaurate at a stirring speed of 200 rpm for 10 minutes to obtain component B; (3) Component A and component B constitute polyurethane coating.

[0045] Example 5. Polyurethane coating control test Take the polyurethane resin coating prepared in Examples 1 to 4 and Comparative Examples 1 to 5 above, apply (the coating amount is 0.5 mg / cm 2 ) were solidified on a glass substrate to obtain samples. Three replicate samples were prepared for each group and fixed in a pipe for water vapor circulation. Each cycle consisted of continuous water vapor flow through the pipe for 5 minutes, followed by ventilation and cooling for 10 minutes. The average number of times each group of samples endured water vapor circulation without bubbling over 72 hours was recorded (decimal values ​​were discarded).

[0046] In actual use, the equipment requiring polyurethane waterproof coating is located near a steam exhaust vent and is inevitably exposed to the effects of this exhaust three times daily. The remainder of the time, the equipment is in a free cooling state to ambient temperature. The above-described water vapor circulation treatment is an accelerated simulation of actual use. The 5-minute water vapor injection period aligns with actual use, while the ventilation cooling accelerates the natural cooling of the simulated equipment. A 72-hour experiment is equivalent to 96 days of actual use. The results are shown in Table 1.

[0047] Table 1. Results of water vapor circulation treatment tolerance test

[0048] As shown in Table 1, the water vapor-resistant polyurethane coatings provided by the present invention can maintain resistance for over 90 days under the aforementioned operating conditions, meeting the equipment maintenance interval. Polyurethane coating No. 2 had a slightly shorter service life, presumably due to the low filler content in component A, which resulted in water vapor intrusion into some micropores, ultimately causing blistering in the corners of the sample.

[0049] Comparative Example 1 is the best example disclosed in the prior art. Its water absorption rate after immersion in distilled water at 60°C for 48 hours is only 0.2%. However, in this tolerance test, bubbling began to appear after only 135 cycles. It is inferred that the reason may be related to the hydroxymethyl cellulose in it. In hot water at 60°C, water molecules still maintain agglomerated state and are not easy to penetrate into the coating; water molecules in water vapor are in a discrete state and are more likely to enter the micropores of the coating. Even though the proportion of hydrophobic fillers in Comparative Example 1 is higher, its water-soluble hydroxymethyl cellulose will still be affected by water molecules, causing the coating structure to gradually develop holes, and therefore cannot pass the experimental test.

[0050] Comparative Example 2 used pentaerythritol, a precursor for synthesizing 4arm-PEG-OH, to provide hydroxyl groups, but the resulting polyurethane coating was poor. Analysis of Comparative Examples 3 and 4 suggests that the lack of PEG chains with an appropriate degree of polymerization prevented the filler from embedding into the four-dimensional network, hindering the coating's compactness and hydrophobicity. Comparative Example 4 may have been due to the overly long PEG chains, resulting in poor filler filling. Alternatively, the overly long PEG chains may have crystallized during polymerization, increasing the material's rigidity.

[0051] Comparative Example 5, which incorporates the silane coupling agent KH570, actually exhibits poor performance in water vapor resistance conditions. This may be because the amino or epoxy groups in the silane coupling agent may partially react with the isocyanate in the polyurethane prepolymer, reducing the number of -NCO groups available for the main reaction and thus affecting the coating's crosslinking density. This makes it difficult to further improve the coating's resistance to water vapor corrosion.

[0052] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A method for preparing a water vapor resistant polyurethane coating, characterized in that: The following steps are involved: (1) uniformly mixing hydroxy vinyl ether, filler, four-arm-polyethylene glycol-hydroxyl group, additives, and solvent to obtain component A; (2) mixing isocyanate and catalyst to obtain component B; (3) Component A and component B constitute the polyurethane coating; The filler includes nano silicon dioxide, nano talc and / or nano montmorillonite.

2. The preparation method according to claim 1, characterized in that The degree of polymerization of the four-arm-polyethylene glycol-hydroxyl group is 20-40 kDa.

3. The preparation method according to claim 1, characterized in that: The hydroxy vinyl ether includes 4-hydroxybutyl vinyl ether and / or triethylene glycol divinyl ether.

4. The preparation method according to claim 1, characterized in that The isocyanate includes at least one of hydrogenated phenylmethane diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate.

5. The preparation method according to claim 1, characterized in that: The auxiliary agent includes at least one of a defoaming agent, sodium lauryl sulfate, and nonylphenol polyethylene glycol.

6. The preparation method according to claim 1, characterized in that: The mass ratio of the hydroxy vinyl ether, filler, and four-arm-polyethylene glycol-hydroxyl group is 1: (0.5-1.5): (0.15-1.5).

7. The preparation method according to claim 1, characterized in that: The mass ratio of the hydroxy vinyl ether to the auxiliary agent and the solvent is 1:(1-5):(8-50).

8. The preparation method according to claim 1, characterized in that: In the component B, the mass ratio of isocyanate to catalyst is 1:(0.1-0.5).

9. The preparation method according to claim 1, characterized in that: The mass ratio of component A to component B is 10:(0.1~2).

10. The preparation method according to claim 1, characterized in that: The following steps are involved: (1) uniformly mixing hydroxy vinyl ether, filler, four-arm-polyethylene glycol-hydroxyl group, auxiliary agent, and solvent to obtain component A, wherein the mass ratio of the hydroxy vinyl ether, filler, and four-arm-polyethylene glycol-hydroxyl group is 1:(0.5-1.5):(1-3); (2) Mixing isocyanate and catalyst to obtain component B, wherein the mass ratio of isocyanate to catalyst is 1:(0.1~0.5); (3) The component A and the component B constitute the polyurethane coating, and the mass ratio of the component A to the component B is 10:(0.1~2); The filler includes nano silicon dioxide, nano talc and / or nano montmorillonite.

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