Sand-erosion resistant photocured coating and use thereof

Abstract

This application relates to the field of polymer materials technology and discloses a sand-erosion-resistant photocurable coating and its application. The sand-erosion-resistant photocurable coating is obtained by uniformly mixing raw materials to obtain a photocurable coating; then coating the photocurable coating onto a substrate and curing it with ultraviolet light; the raw materials include: 5-30 parts of a fluorinated polyurethane macromolecular photoinitiator; 1-5 parts of a hydrogen-abstracting small molecule photoinitiator; 30-90 parts of a monofunctional acrylate monomer; 10-60 parts of a polyfunctional acrylate crosslinking agent; 0-20 parts of a diacrylate-terminated oligomer; and 0-30 parts of a solvent. The coating of this application forms a longitudinal modulus and light gradient on the surface through the self-assembly of the fluorinated polyurethane macromolecular photoinitiator, creating a surface wrinkle pattern with a high aspect ratio (approximately 0.7). This effectively prevents continuous micro-cutting, ploughing, and fatigue spalling damage to the substrate surface by hard particles, and its protective ability for the substrate is significantly superior to traditional smooth sand-erosion-resistant coatings.

Description

Technical Field

[0001] This application relates to the field of polymer materials technology, specifically to a photocurable coating resistant to sand erosion and its application. Background Technology

[0002] In modern engineering fields such as aircraft, wind turbines, and high-speed rail, a large amount of equipment and infrastructure are subjected to harsh outdoor environments for extended periods. During service, they inevitably suffer from the continuous erosion caused by high-speed solid particles (such as sand and ice crystals) and droplets (such as raindrops and fog droplets). Sand erosion caused by high-speed particle impact has become one of the key failure modes restricting the reliability, operational efficiency, and service life of equipment. From the perspective of damage mechanism, sand erosion mainly manifests as micro-cutting, plowing, and fatigue spalling of material surfaces by hard particles. This type of damage can accelerate the degradation process of material properties, induce coating peeling, component wear, and even structural integrity failure, seriously threatening the safe operation of equipment, while also bringing high maintenance costs and significant economic losses.

[0003] To address these challenges, developing high-performance sand erosion-resistant protective coatings is considered one of the most cost-effective technological approaches. Based on material systems, existing sand erosion-resistant protective coatings are mainly classified into three categories: ceramic-based, metal-based, and organic polymer-based. Ceramic-based coatings have high hardness and excellent wear resistance, but poor toughness, making them prone to brittle cracking, and their interfacial bonding stability still needs improvement. Metal-based coatings have excellent mechanical properties, but their high density results in relatively insufficient corrosion resistance, increasing structural load and easily inducing corrosion failure. Organic polymer-based coatings, such as epoxy resins and polyurethanes, have the advantages of highly designable molecular structures and simple construction processes, and are currently the most widely used. However, their resistance to environmental aging and resistance to sharp particle cutting are poor, and existing research mainly focuses on optimizing single performance indicators, lacking systematic exploration of synergistic improvements in multiple performance aspects.

[0004] Therefore, it is of great significance to develop new sand-erosion resistant coatings that exhibit good adaptability to various substrate types and can be applied to fields such as aviation, wind power, and rail transportation. Summary of the Invention

[0005] This application provides a photocurable coating resistant to sand erosion and its application, aiming to solve the technical problems of existing sand erosion resistant protective coatings, such as poor resistance to environmental aging, weak resistance to sharp particle cutting, and limited coating functions.

[0006] To achieve the above objectives, the present application adopts the following technical solution.

[0007] In a first aspect, this application provides a sand-erosion-resistant photocurable coating, wherein raw materials are mixed uniformly to obtain a photocurable coating; the photocurable coating is then applied to a substrate and cured by ultraviolet light to obtain a sand-erosion-resistant photocurable coating;

[0008] The raw materials, by weight, include:

[0009] 5-30 parts of fluorinated polyurethane macromolecular photoinitiator;

[0010] 1-5 parts of hydrogen-abstracting small molecule photoinitiator;

[0011] 30-90 parts of monofunctional acrylate monomer;

[0012] 10-60 parts of multifunctional acrylate crosslinking agent;

[0013] 0-20 parts of diacrylate-terminated oligomers;

[0014] Solvent: 0-30 parts.

[0015] Preferably, the chemical structure of the fluorinated polyurethane macromolecular photoinitiator is shown in formula (1):

[0016] ;

[0017] Equation (1)

[0018] Where m is a positive integer;

[0019] R2 is an alkyl chain or alkyl ring; R3 and R4 are independently alkyl chains, alkyl rings or aromatic rings; R5 and R6 are independently hydroxyl or amino groups.

[0020] R1 is selected from any of the following structures:

[0021] ;

[0022] R 20 Choose from any of the following structures:

[0023] ;

[0024] R 21 Choose from any of the following structures:

[0025] ;

[0026] Among them, x, y, and z are each independent positive integers;

[0027] R 22 Choose from any of the following structures:

[0028] ;

[0029] Where a, b, c, and d each independently represent positive integers.

[0030] More preferably, the fluorinated polyurethane macromolecular photoinitiator is prepared by the following method:

[0031] S1, Compound 1, Compound 2 and a weak base are dissolved in an organic solvent and refluxed under an inert atmosphere; after the reaction is complete, the organic phase is collected by washing with deionized water and extraction with dichloromethane, dried and the solvent is removed by rotary evaporation to obtain the polyurethane precursor.

[0032] Compound 1 is selected from any of the following chemical structures:

[0033] ;

[0034] Where X is a halogen;

[0035] The chemical structure of compound 2 is shown in formula (2): Equation (2)

[0036] The chemical structure of the polyurethane precursor is shown in formula (3): Equation (3)

[0037] S2, a mixed solution is obtained by dissolving polyurethane precursor, low surface energy fluorinated prepolymer, chain extender and diisocyanate in an organic solvent;

[0038] Under inert gas protection, the mixed solution is heated to carry out a polymerization reaction to obtain a polyurethane solution;

[0039] The solid and liquid components in the polyurethane solution are separated using a poor solvent. The solid is collected and dried to obtain a fluorinated polyurethane macromolecular photoinitiator.

[0040] More preferably, the weak base is any one of anhydrous potassium carbonate, anhydrous sodium carbonate, sodium bicarbonate, potassium bicarbonate, ammonia, or ammonium bicarbonate.

[0041] The organic solvent is any one of tetrahydrofuran, acetone, dichloromethane, chloroform, dioxane, butanone, ethyl acetate, DMF, DMSO, toluene, ethanol, or methanol;

[0042] The low surface energy fluorinated prepolymer is a C1-C30 divalent alkyl group with partially or completely substituted fluorine atoms at the end of a dihydroxyl group.

[0043] Alternatively, the low surface energy fluorinated prepolymer is a C1-C30 divalent silanoxy group with partially or completely substituted fluorine atoms at the end of a dihydroxyl group.

[0044] The chain extender is a dihydroxy-terminated oligomer.

[0045] More preferably, the low surface energy fluorinated prepolymer is selected from any one of the following compounds:

[0046] ;

[0047] The chain extender is a polyester diol or polyether diol with a molecular weight of 500-5000.

[0048] The diisocyanate is selected from any one of the following compounds:

[0049] .

[0050] More preferably, the molar ratio of compound 1, compound 2 and the weak base is 1:2~10:2~10;

[0051] The molar ratio of the polyurethane precursor, the low surface energy fluorinated prepolymer, and the chain extender is 1:1~10:0.1~1;

[0052] In the polyurethane precursor, low surface energy fluorinated prepolymer, chain extender and diisocyanate system, the molar ratio of hydroxyl groups to isocyanate groups is 1:1 to 7:6.

[0053] The low surface energy segments of the fluorinated prepolymer have a molecular weight of 500-3000 g / mol.

[0054] Preferably, the hydrogen-abstracting small molecule photoinitiator comprises any one of the following compounds:

[0055] .

[0056] Preferably, the monofunctional acrylate monomer comprises any one of isooctyl acrylate, isobornyl acrylate, tetrahydrofurfuryl acrylate, lauryl acrylate, benzyl acrylate, methyl methacrylate, isobornyl methacrylate, hydroxyethyl methacrylate, glycidyl methacrylate, 2-phenoxyethyl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, 4-acryloylmorpholine, cyclic trimethylolpropane formal acrylate, n-butyl acrylate, or polyethylene glycol o-phenylphenyl ether acrylate.

[0057] The multifunctional acrylate crosslinking agent includes any one of 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, neopentyl glycol diacrylate, ethoxylated bisphenol A diacrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, bis(trimethylolpropane tetraacrylate) or tri(2-hydroxyethyl)isocyanurate triacrylate;

[0058] The diacrylate-terminated oligomers include at least one of polyester polyurethane acrylate, polyether polyurethane acrylate, polyester acrylate, or polyether acrylate.

[0059] The solvent is any one of ethyl acetate, butyl acetate, tetrahydrofuran, or ethanol.

[0060] Preferably, the coating is applied by dripping, scraping, or spraying;

[0061] The wavelength for UV curing is 254~450 nm; the light intensity is 1~10000 mW / cm². 2 Illumination time > 5 s.

[0062] A second aspect of this application provides the application of the aforementioned sand-resistant photocurable coating in aircraft, wind turbine generators, and high-speed rail transportation.

[0063] Compared with the prior art, the beneficial effects of this application are as follows:

[0064] 1) Unlike the flat structure of traditional sand-resistant coatings, the coating of this application forms a longitudinal modulus and light gradient on the surface through the self-assembly of a fluorinated polyurethane macromolecular photoinitiator, forming a surface wrinkle pattern with a high aspect ratio (about 0.7). This effectively prevents damage to the substrate surface from continuous micro-cutting, plowing, and fatigue spalling by hard particles. Therefore, its protection ability for the substrate is significantly better than that of flat coatings.

[0065] 2) In the coating of this application, the fluorinated segments have ultra-low surface energy, which can drive the fluorinated macromolecular initiator to accumulate from the inside of the resin to the surface and undergo self-assembly on the surface, thereby inhibiting the oxygen inhibition phenomenon during the photocuring process of the coating and making the coating surface fully cured and non-sticky.

[0066] 3) In the coating of this application, the enrichment of fluorine-containing segments on the surface can significantly improve the hardness of the coating, reduce the surface friction coefficient, improve the hydrophobicity of the coating surface, and thus enhance the coating's corrosion resistance, self-cleaning ability, anti-icing and anti-frost ability, breaking through the limitation of the single function of traditional polymer-based sand-erosion resistant coatings.

[0067] 4) The fluorinated polyurethane macromolecular photoinitiator in the coating of this application has strong molecular designability. Different functional groups can be introduced into the macromolecular photoinitiator to make the coating have specific functions to adapt to different application scenarios.

[0068] 5) The coating of this application can bond tightly with a variety of substrates, has strong anti-peeling ability, good coating toughness and is not easy to crack, has a long service life and a wide range of applications. Attached Figure Description

[0069] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0070] Figure 1 The following are the proton NMR spectra of the polyurethane precursors in Examples 1-4;

[0071] Figure 2 The following are the carbon NMR spectra of the polyurethane precursors in Examples 1-4;

[0072] Figure 3 The following are the 1H NMR spectra of the fluorinated polyurethane macromolecular photoinitiators in Examples 1-4;

[0073] Figure 4 The NMR fluorine spectra of the fluorinated polyurethane macromolecular photoinitiators in Examples 1-4 are shown below.

[0074] Figure 5 The gel permeation chromatograms are of the fluorinated polyurethane macromolecular photoinitiators in Examples 1-4;

[0075] Figure 6 The graphs show the changes in double bond conversion rate of the photocurable coatings in Examples 1-4 during the photocuring process.

[0076] Figure 7 These are laser confocal microscope images of the sand-resistant photocurable coatings of Examples 1-4;

[0077] Figure 8 The graph shows the test results of the sand erosion resistance of the photocurable coatings in Examples 1-4;

[0078] Figure 9 The figures show the contact angle test results of the photocurable coatings resistant to sand erosion in Examples 1-4. Detailed Implementation

[0079] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0080] In the following description of this embodiment, the terms "including", "comprising", "having", and "containing" are all open-ended terms, meaning that they include but are not limited to.

[0081] In the following description of this embodiment, the term "and / or" is used to describe the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, B existing alone, and A and B existing simultaneously. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0082] In the following description of this embodiment, the term "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0083] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms "a" and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0084] Those skilled in the art should understand that, in the following description of the embodiments of this application, the sequence of numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0085] Those skilled in the art will understand that the numerical ranges in the embodiments of this application should be understood as each intermediate value between the upper and lower limits of the specifically disclosed range. Each smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this application. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0086] Unless otherwise stated, the technical / scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. While this application describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this application. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0087] This application provides a sand-erosion-resistant photocurable coating, which is obtained by uniformly mixing raw materials to obtain a photocurable coating; then the photocurable coating is applied to a substrate and cured by ultraviolet light to obtain a sand-erosion-resistant photocurable coating;

[0088] The raw materials, by weight, include:

[0089] 5-30 parts of fluorinated polyurethane macromolecular photoinitiator;

[0090] 1-5 parts of hydrogen-abstracting small molecule photoinitiator;

[0091] 30-90 parts of monofunctional acrylate monomer;

[0092] 10-60 parts of multifunctional acrylate crosslinking agent;

[0093] 0-20 parts of diacrylate-terminated oligomers;

[0094] Solvent: 0-30 parts.

[0095] In this application, the photocurable coating can be applied to the substrate by dripping, scraping, or spraying.

[0096] The ultraviolet curing process uses ultraviolet light with a wavelength of 254~450 nm and a light intensity of 1~10000 mW / cm². 2 UV curing time > 5 s.

[0097] The coating of this application forms a longitudinal modulus and light gradient on the surface through the self-assembly of a fluorinated polyurethane macromolecular photoinitiator, resulting in a surface wrinkle pattern with a high aspect ratio (about 0.7). This effectively prevents damage to the substrate surface from continuous micro-cutting, plowing, and fatigue spalling by hard particles. Its protection ability for the substrate is significantly better than that of traditional smooth and sand-resistant coatings.

[0098] Furthermore, the coating of this application, due to the ultra-low surface energy of its fluorinated segments, can drive the fluorinated macromolecular initiator to accumulate from the resin interior to the surface, undergoing self-assembly on the surface. This inhibits oxygen inhibition during the photocuring process, ensuring the coating surface is fully cured and non-sticky. The accumulation of fluorinated segments on the surface significantly improves the coating's hardness, reduces the surface friction coefficient, and enhances its hydrophobicity, thereby strengthening its corrosion resistance, self-cleaning ability, and anti-icing and anti-frost capabilities, overcoming the limitations of traditional polymer-based anti-sand coatings with their single function.

[0099] In this application, the chemical structure of the fluorinated polyurethane macromolecular photoinitiator is shown in formula (1):

[0100] ;

[0101] Equation (1)

[0102] Where m is a positive integer;

[0103] R2 is an alkyl chain or alkyl ring; R3 and R4 are independently alkyl chains, alkyl rings or aromatic rings; R5 and R6 are independently hydroxyl or amino groups.

[0104] R1 is selected from any of the following structures:

[0105] ;

[0106] R 20 Choose from any of the following structures:

[0107] ;

[0108] R 21 Choose from any of the following structures:

[0109] ;

[0110] Among them, x, y, and z are each independent positive integers;

[0111] R 22 Choose from any of the following structures:

[0112] ;

[0113] Where a, b, c, and d each independently represent positive integers.

[0114] The fluorinated polyurethane macromolecular photoinitiator described in this application is prepared by the following method:

[0115] S1, Compound 1, Compound 2 and a weak base are dissolved in an organic solvent and refluxed under an inert atmosphere; after the reaction is complete, the organic phase is collected by washing with deionized water and extraction with dichloromethane, dried and the solvent is removed by rotary evaporation to obtain the polyurethane precursor.

[0116] Compound 1 is selected from any of the following chemical structures:

[0117] ;

[0118] Where X is a halogen;

[0119] As a preferred option, compound 1 may be any one of the following compounds:

[0120] ; ; ;

[0121] The chemical structure of compound 2 is shown in formula (2):

[0122] Equation (2)

[0123] As a preferred option, compound 2 can be selected from... or .

[0124] The chemical structure of the polyurethane precursor is shown in formula (3):

[0125] Equation (3)

[0126] As a preferred embodiment, the chemical structure of the polyurethane precursor is shown in any of the following:

[0127] ; ;

[0128] The weak base is any one of anhydrous potassium carbonate, anhydrous sodium carbonate, sodium bicarbonate, potassium bicarbonate, ammonia, or ammonium bicarbonate; the weak base is used to provide an alkaline environment to react with the hydrogen halides generated during the reaction and promote the reaction.

[0129] The organic solvent is any one of tetrahydrofuran, acetone, dichloromethane, chloroform, dioxane, butanone, ethyl acetate, DMF, DMSO, toluene, ethanol, or methanol.

[0130] In this application, the molar ratio of compound 1, compound 2 and the weak base is 1:2~10:2~10.

[0131] S2, a mixed solution is obtained by dissolving polyurethane precursor, low surface energy fluorinated prepolymer, chain extender and diisocyanate in an organic solvent;

[0132] Under inert gas protection, the mixed solution is heated to carry out a polymerization reaction to obtain a polyurethane solution;

[0133] The solid and liquid components in the polyurethane solution are separated using a poor solvent. The solid is collected and dried to obtain a fluorinated polyurethane macromolecular photoinitiator.

[0134] In this application, the low surface energy fluorinated prepolymer comprises one or more of C1-C30 divalent alkyl or divalent silanoxy groups with partially or completely substituted fluorine atoms at the dihydroxyl-terminated end; preferably, its molecular weight is 500-3000 g / mol. As a preferred embodiment, it is selected from any one of the following compounds:

[0135] ;

[0136] The chain extender is a dihydroxy-terminated oligomer, preferably a polyester diol or polyether diol with a molecular weight of 500 to 5000.

[0137] The diisocyanate is selected from any one of the following compounds:

[0138] .

[0139] In this application, the molar ratio of the polyurethane precursor, the low surface energy fluorinated prepolymer, and the chain extender is 1:1 to 10:0.1 to 1. In the polyurethane precursor, the low surface energy fluorinated prepolymer, the chain extender, and the diisocyanate system, the molar ratio of hydroxyl groups to isocyanate groups is 1:1 to 7:6.

[0140] In the raw materials of the photocurable coating resistant to sand erosion of this application, the hydrogen-abstracting small molecule photoinitiator includes any one of the following compounds:

[0141] ;

[0142] Preferably, the hydrogen-abstracting small molecule photoinitiator is selected from any one of 4,4'-bis(dimethylamino)benzophenone, 2-isopropylthioxanthanone, benzophenone or 2,4-diethylthioxanthanone.

[0143] In the raw materials of the photocurable coating resistant to sand erosion of this application, the monofunctional acrylate monomer is selected from any one of isooctyl acrylate, isobornyl acrylate, tetrahydrofurfuryl acrylate, lauryl acrylate, benzyl acrylate, methyl methacrylate, isobornyl methacrylate, hydroxyethyl methacrylate, glycidyl methacrylate, 2-phenoxyethyl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, 4-acryloylmorpholine, cyclic trimethylolpropane formal acrylate, n-butyl acrylate, or polyethylene glycol o-phenylphenyl ether acrylate; preferably any one of 4-acryloylmorpholine, isobornyl acrylate, cyclic trimethylolpropane formal acrylate, or n-butyl acrylate.

[0144] In the raw materials of the photocurable coating resistant to sand erosion of this application, the multifunctional acrylate crosslinking agent is selected from any one of 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, neopentyl glycol diacrylate, ethoxylated bisphenol A diacrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, bis(trimethylolpropane tetraacrylate) or tri(2-hydroxyethyl) isocyanurate triacrylate; preferably any one of tri(2-hydroxyethyl) isocyanurate triacrylate, trimethylolpropane triacrylate, 1,6-hexanediol diacrylate or pentaerythritol tetraacrylate.

[0145] In the raw materials of the photocurable coating resistant to sand erosion of this application, the oligomers with diacrylate end-capping include at least one of polyester polyurethane acrylate, polyether polyurethane acrylate, polyester acrylate, or polyether acrylate, such as S5B polyether acrylate, S3F aliphatic polyether polyurethane acrylate, S5Q2 aliphatic polyether polyurethane acrylate, 66026 aliphatic polyester polyurethane acrylate, or PPGDA polyether acrylate from Jiaxing Sudi Polymer Materials Co., Ltd.

[0146] The solvent is any one of ethyl acetate, butyl acetate, tetrahydrofuran, or ethanol.

[0147] The photocurable coating resistant to sand erosion of this application can bond tightly to a variety of substrates, has strong anti-peeling ability, good coating toughness and is not easy to crack, has a long service life, and is suitable for a wide range of applications. The fluorinated polyurethane macromolecular photoinitiator has strong molecular designability, and different functional groups can be introduced into the macromolecular photoinitiator to give the coating specific functions to adapt to different application scenarios.

[0148] Specifically, the photocurable coating for sand erosion resistance of this application can be used in fields such as aircraft, wind turbine generators, and high-speed rail transportation.

[0149] The present application will be further described below through specific embodiments.

[0150] Example 1

[0151] This embodiment provides a fluorinated polyurethane macromolecular photoinitiator and a sand-erosion-resistant photocurable coating, the preparation method of which includes the following steps:

[0152] Step 1: Preparation of fluorinated polyurethane macromolecular photoinitiator

[0153] S1, precursor for synthesizing polyurethane

[0154] Weigh 100 mmol (1 equiv) of 4-(bromomethyl)benzophenone, 200 mmol (2 equiv) of diethanolamine, and 300 mmol (3 equiv) of anhydrous potassium carbonate into a reaction vessel. Slowly add 100 mL of tetrahydrofuran to the reaction vessel and stir until the reactants are fully dissolved. Protect the reaction vessel with nitrogen, then heat to 60 °C and reflux for 48 h. After the reaction is complete, pour the reaction solution into 1000 mL of deionized water, add 50 mL of dichloromethane to extract three times and collect the organic phase. Wash three times with saturated brine, then remove residual water from the organic phase with anhydrous magnesium sulfate. Finally, remove the solvent using a rotary evaporator to obtain a light yellow liquid, which is the polyurethane precursor. The synthesis process is as follows:

[0155] ;

[0156] Structural analysis was performed on the polyurethane precursor, and its proton NMR spectrum is shown below. Figure 1 The image above shows the carbon NMR spectrum. Figure 2 As shown in the image above.

[0157] from Figure 1 It can be seen that the signals of each hydrogen atom in the polyurethane precursor molecule can be found at the corresponding positions in the proton NMR spectrum, and the integrated area of ​​each peak corresponds to the number of hydrogen atoms, proving that the polyurethane precursor was successfully synthesized with high purity and no impurities.

[0158] from Figure 2 It can be seen that the signals of each carbon atom in the polyurethane precursor molecule can be found at the corresponding positions in the carbon NMR spectrum, proving that the polyurethane precursor was successfully synthesized.

[0159] S2, Synthesis of photoinitiators for fluorinated polyurethane macromolecules

[0160] The polyurethane precursor (16 mmol, 4 equiv), dihydroxy-terminated polytetrahydrofuran (weight average molecular weight 1000) (8 mmol, 2 equiv), and perfluoropolyether surfactant (Fluorolink D10 H, weight average molecular weight 1000) (4 mmol, 1 equiv) were sequentially added to a three-necked reaction flask. Then, 0.1% of the total mass of the reactants was added as a catalyst. After mixing the reactants, the mixture was vacuum-dried at 80°C for 1 h to remove water.

[0161] The reaction apparatus, after being evacuated, was protected under a nitrogen atmosphere. 100 mL of anhydrous N,N-dimethylformamide was added, and the mixture was mechanically stirred for 10 min. After the reactants dissolved, isophorone diisocyanate (24 mmol, 6 equiv) was slowly added using a syringe, followed by mechanical stirring at 80 °C for 8 h. After the reaction was complete, the solution was cooled to room temperature, and then the reaction solution was precipitated in 1000 mL of anhydrous diethyl ether and dried in a forced-air oven to obtain a yellow solid, which is the fluorinated polyurethane macromolecular photoinitiator. The synthesis process is as follows:

[0162] ;

[0163] Where f is a positive integer.

[0164] Step 2: Prepare a photocurable coating resistant to sand erosion.

[0165] Weigh the following parts by weight of raw materials:

[0166] 10 parts of fluorinated polyurethane macromolecular photoinitiator

[0167] 2 parts of 2-isopropylthioxanthone

[0168] 65 parts of cyclic trimethylolpropane acetal acrylate

[0169] 25 parts of tri(2-hydroxyethyl)isocyanurate triacrylate

[0170] 10 parts of diacrylate-terminated polytetrahydrofuran (weight average molecular weight 7000) oligomer

[0171] 10 parts of ethyl acetate

[0172] Mix the above raw materials evenly to obtain a light-curable coating;

[0173] The above-mentioned photocurable coating was applied to a polyethylene terephthalate film using a 200-micron wire rod, and dried in an oven at 60°C for 30 min. Subsequently, it was treated with light at a wavelength of 365 nm and an intensity of 600 mW / cm². 2 After irradiating with ultraviolet light for 2 minutes, a photocurable coating resistant to sand erosion is obtained.

[0174] Among them, the double bond conversion rate change curve of the photocurable coating during the photocuring process (real-time infrared monitoring) is as follows: Figure 8 As shown. From Figure 8 It can be seen that the photocuring rate of the photocurable coating is relatively fast, and it can be completely cured within 1 minute, resulting in a high double bond conversion rate.

[0175] Example 2

[0176] This embodiment provides a fluorinated polyurethane macromolecular photoinitiator and a sand-erosion-resistant photocurable coating, the preparation method of which includes the following steps:

[0177] Step 1: Preparation of fluorinated polyurethane macromolecular photoinitiator

[0178] S1, precursor for synthesizing polyurethane

[0179] Weigh 100 mmol (1 equiv) of 4-(chloromethyl)benzophenone, 300 mmol (2 equiv) of diethanolamine, and 500 mmol (3 equiv) of anhydrous potassium carbonate into a reaction vessel. Slowly add 150 mL of tetrahydrofuran to the reaction vessel and stir until the reactants are fully dissolved. Protect the reaction vessel with nitrogen, then heat to 60 °C and reflux for 48 h. After the reaction is complete, pour the reaction solution into 1500 mL of deionized water, add 80 mL of dichloromethane to extract three times, collect the organic phase, wash three times with saturated brine, remove residual water from the organic phase with anhydrous magnesium sulfate, and then remove the solvent using a rotary evaporator to obtain a light yellow liquid, which is the polyurethane precursor. The synthesis process is as follows:

[0180] ;

[0181] Structural analysis was performed on the polyurethane precursor, and its proton NMR spectrum is shown below. Figure 1 The image above shows the carbon NMR spectrum. Figure 2 As shown in the image above.

[0182] S2, Synthesis of photoinitiators for fluorinated polyurethane macromolecules

[0183] Polyurethane precursor (16 mmol, 4 equiv), dihydroxyl-terminated polyethylene glycol (weight average molecular weight 2000) (4 mmol, 1 equiv), and poly(perfluoroethoxymethoxydifluoroethyl) PEG ether (Fluorolink E10 H, weight average molecular weight 2000) (2 mmol, 1 equiv) were sequentially added to a three-necked reaction flask. Then, 0.1% of the total mass of the reactants was added as a catalyst. After mixing the reactants, the mixture was vacuum-dried at 80°C for 1 h to remove water.

[0184] The reaction apparatus, after being evacuated, was protected under a nitrogen atmosphere. 100 mL of anhydrous N,N-dimethylformamide was added, and the mixture was mechanically stirred for 10 min. After the reactants dissolved, diphenylmethane diisocyanate (20 mmol, 5 equiv) was slowly added using a syringe, followed by mechanical stirring at 80 °C for 8 h. After the reaction was complete, the solution was cooled to room temperature, and then the reaction solution was precipitated in 1000 mL of anhydrous diethyl ether. The precipitate was dried in a forced-air oven to obtain a yellow solid, which is the fluorinated polyurethane macromolecular photoinitiator. The synthesis process is as follows:

[0185] ;

[0186] Step 2: Prepare a photocurable coating resistant to sand erosion.

[0187] Weigh the following parts by weight of raw materials:

[0188] 15 parts of fluorinated polyurethane macromolecular photoinitiator

[0189] 3 parts of 2-isopropylthioxanthone

[0190] 50 parts of 4-acryloylmorpholine

[0191] 40 parts of glycerol trihydroxypropyl ether triacrylate

[0192] 5 parts of diacrylate-terminated polyethylene glycol (weight average molecular weight 4000) oligomer

[0193] 20 parts of butyl acetate

[0194] Mix the above raw materials evenly to obtain a light-curable coating;

[0195] The photocurable coating was applied to the polyethylene terephthalate film using a 150-micron wire rod, and dried in an oven at 60°C for 30 min. Subsequently, it was treated with light at a wavelength of 365 nm and an intensity of 800 mW / cm². 2 After irradiating with ultraviolet light for 2 minutes, a photocurable coating resistant to sand erosion is obtained.

[0196] Example 3

[0197] This embodiment provides a fluorinated polyurethane macromolecular photoinitiator and a sand-erosion-resistant photocurable coating, the preparation method of which includes the following steps:

[0198] Step 1: Preparation of fluorinated polyurethane macromolecular photoinitiator

[0199] S1, precursor for synthesizing polyurethane

[0200] Weigh 100 mmol (1 equiv) of 4-(fluoromethyl)benzophenone, 500 mmol (5 equiv) of diethanolamine, and 500 mmol (5 equiv) of anhydrous sodium carbonate into a reaction vessel. Slowly add 150 mL of tetrahydrofuran to the reaction vessel and stir until the reactants are fully dissolved. Protect the reaction vessel with nitrogen, then heat to 60 °C and reflux for 48 hours. After the reaction is complete, pour the reaction solution into 1500 mL of deionized water, add 100 mL of dichloromethane to extract three times, collect the organic phase, wash three times with saturated brine, remove residual water from the organic phase with anhydrous magnesium sulfate, and then remove the solvent using a rotary evaporator to obtain a light yellow liquid, which is the polyurethane precursor. The synthesis process is as follows:

[0201] ;

[0202] Structural analysis was performed on the polyurethane precursor, and its proton NMR spectrum is shown below. Figure 1 The image above shows the carbon NMR spectrum. Figure 2 As shown in the image above.

[0203] S2, Synthesis of photoinitiators for fluorinated polyurethane macromolecules

[0204] The polyurethane precursor (16 mmol, 4 equiv), dihydroxyl-terminated polycaprolactone (weight average molecular weight 1000) (8 mmol, 2 equiv), and perfluoropolyether surfactant (Fluorolink D10 H, weight average molecular weight 1000) (4 mmol, 1 equiv) were sequentially added to a three-necked reaction flask. Then, 0.1% of the total mass of the reactants was added as a catalyst. After mixing the reactants, the mixture was vacuum-dried at 80°C for 1 h to remove water.

[0205] The reaction apparatus, after being evacuated, was protected under a nitrogen atmosphere. 100 mL of anhydrous N,N-dimethylformamide was added, and the mixture was mechanically stirred for 10 min. After the reactants dissolved, hexamethylene diisocyanate (24 mmol, 6 equiv) was slowly added using a syringe, followed by mechanical stirring at 80 °C for 8 h. After the reaction was complete, the solution was cooled to room temperature, and then the reaction solution was precipitated in 1000 mL of anhydrous diethyl ether. The precipitate was dried in a forced-air oven to obtain a yellow solid, which is the fluorinated polyurethane macromolecular photoinitiator. The synthesis process is as follows:

[0206] ;

[0207] Step 2: Prepare a photocurable coating resistant to sand erosion.

[0208] Weigh the following parts by weight of raw materials:

[0209] 10 parts of fluorinated polyurethane macromolecular photoinitiator

[0210] 3 parts of 4,4'-bis(dimethylamino)benzophenone

[0211] 70 parts of acrylic isoborneol

[0212] 30 parts of trimethylolpropane triacrylate

[0213] 10 parts of diacrylate-terminated polycaprolactone (weight average molecular weight 10,000) oligomer

[0214] 20 parts of tetrahydrofuran

[0215] Mix the above raw materials evenly to obtain a light-curable coating;

[0216] The photocurable coating was applied to the polyethylene terephthalate film using a 200-micron wire rod, and dried in an oven at 60°C for 30 min. Subsequently, it was treated with light at a wavelength of 365 nm and an intensity of 600 mW / cm². 2 After irradiating with ultraviolet light for 2 minutes, a photocurable coating resistant to sand erosion is obtained.

[0217] Example 4

[0218] This embodiment provides a fluorinated polyurethane macromolecular photoinitiator and a sand-erosion-resistant photocurable coating, the preparation method of which includes the following steps:

[0219] Step 1: Preparation of fluorinated polyurethane macromolecular photoinitiator

[0220] S1, precursor for synthesizing polyurethane

[0221] Weigh 100 mmol (1 equiv) of 4-(bromomethyl)benzophenone, 300 mmol (5 equiv) of diisopropanolamine, and 500 mmol (5 equiv) of anhydrous potassium carbonate into a reaction vessel. Slowly add 150 mL of tetrahydrofuran to the reaction vessel and stir until the reactants are fully dissolved. Protect the reaction vessel with nitrogen, then heat to 60 °C and reflux for 48 hours. After the reaction is complete, pour the reaction solution into 1500 mL of deionized water, add 100 mL of dichloromethane to extract three times, collect the organic phase, wash three times with saturated brine, remove residual water from the organic phase with anhydrous magnesium sulfate, and then remove the solvent using a rotary evaporator to obtain a light yellow liquid, which is the polyurethane precursor. The synthesis process is as follows:

[0222] Structural analysis was performed on the polyurethane precursor, and its proton NMR spectrum is shown below. Figure 1 The following figure shows the carbon NMR spectrum: Figure 2 The image below is shown.

[0223] from Figure 1 It can be seen that the signals of each hydrogen atom in the polyurethane precursor molecule can be found at the corresponding positions in the proton NMR spectrum, and the integrated area of ​​each peak corresponds to the number of hydrogen atoms, proving that the polyurethane precursor was successfully synthesized with high purity and no impurities.

[0224] from Figure 2 It can be seen that the signals of each carbon atom in the polyurethane precursor molecule can be found at the corresponding positions in the carbon NMR spectrum, proving that the polyurethane precursor was successfully synthesized.

[0225] S2, Synthesis of photoinitiators for fluorinated polyurethane macromolecules

[0226] The polyurethane precursor (16 mmol, 4 equiv), dihydroxy-terminated polytetrahydrofuran (weight average molecular weight 4000) (2 mmol, 0.5 equiv), and perfluoropolyether surfactant (Fluorolink D10 H, weight average molecular weight 2000) (2 mmol, 0.5 equiv) were sequentially added to a three-necked reaction flask. Then, 0.1% of the total mass of the reactants was added as a catalyst. After mixing the reactants, the mixture was vacuum dehydrated at 80 °C for 1 h.

[0227] The reaction apparatus, after being evacuated, was protected under a nitrogen atmosphere. 100 mL of anhydrous N,N-dimethylformamide was added, and the mixture was mechanically stirred for 10 min. After the reactants dissolved, isophorone diisocyanate (24 mmol, 6 equiv) was slowly added using a syringe, followed by mechanical stirring at 80 °C for 8 h. After the reaction was complete, the solution was cooled to room temperature, and then the reaction solution was precipitated in 1000 mL of anhydrous diethyl ether. The precipitate was dried in a forced-air oven to obtain a yellow solid, which is the fluorinated polyurethane macromolecular photoinitiator. The synthesis process is as follows:

[0228] ;

[0229] Step 2: Prepare a photocurable coating resistant to sand erosion.

[0230] Weigh the following parts by weight of raw materials:

[0231] 15 parts of fluorinated polyurethane macromolecular photoinitiator

[0232] 3 parts of 4,4'-bis(dimethylamino)benzophenone

[0233] 60 parts of n-butyl acrylate

[0234] 30 parts of polyethylene glycol diacrylate (weight average molecular weight 200)

[0235] 10 parts of diacrylate-terminated polyurethane (weight average molecular weight 3000) oligomer

[0236] 20 parts of ethanol

[0237] Mix the above raw materials evenly to obtain a light-curable coating;

[0238] The previously mixed photocurable resin was coated onto the polyethylene terephthalate film using a 200-micron wire rod. The film was then dried in an oven at 60°C for 30 minutes, followed by exposure to light at a wavelength of 365 nm and an intensity of 600 mW / cm². 2 After irradiating with ultraviolet light for 3 minutes, a photocurable coating resistant to sand erosion is obtained.

[0239] Structural analysis was performed on the fluorinated polyurethane macromolecular photoinitiators prepared in Examples 1-4, and their proton NMR spectra are shown below. Figure 3 As shown, the nuclear magnetic resonance fluorine spectrum is as follows: Figure 4 As shown.

[0240] from Figure 3 It can be seen that the signals of each hydrogen atom in the fluorinated polyurethane macromolecular photoinitiator can be found at the corresponding positions in the proton NMR spectrum, and the integrated area of ​​each peak corresponds to the number of hydrogen atoms, proving that the fluorinated polyurethane macromolecular photoinitiator has been successfully synthesized, and the proportion of each structural unit corresponds to the feed ratio.

[0241] from Figure 4 It can be seen that the signals of each fluorine atom in the fluorinated polyurethane macromolecular photoinitiator can be found at the corresponding positions in the nuclear magnetic resonance fluorine spectrum, proving that the fluorinated polyurethane macromolecular photoinitiator has been successfully synthesized.

[0242] Gel permeation chromatography of fluorinated polyurethane macromolecular photoinitiators, such as Figure 5 As shown. From Figure 5 It can be seen that the number-average molecular weight of the fluorinated polyurethane macromolecular photoinitiator in Example 1 is about 13k, and the molecular weight distribution is about 1.5; the number-average molecular weight of the fluorinated polyurethane macromolecular photoinitiator in Example 2 is about 17k, and the molecular weight distribution is about 1.4; the number-average molecular weight of the fluorinated polyurethane macromolecular photoinitiator in Example 3 is about 24k, and the molecular weight distribution is about 1.9; and the number-average molecular weight of the fluorinated polyurethane macromolecular photoinitiator in Example 4 is about 9k, and the molecular weight distribution is about 1.5.

[0243] The morphology and performance of the photocurable coating resistant to sand erosion prepared in Example 1 were characterized and tested to verify its performance.

[0244] In Examples 1-4, the double bond conversion rate change curves of the photocurable coatings during the photocuring process (real-time infrared monitoring) are as follows: Figure 6 As shown. From Figure 6It can be seen that the photocuring rate of the photocurable coating is relatively fast, and it can be completely cured within 1 minute, resulting in a high double bond conversion rate.

[0245] The surface morphology of the coating was observed using a laser confocal microscope, and the results are as follows: Figure 7 As shown. From Figure 7 It can be seen that disordered wrinkle patterns were generated on the coating surface, proving the effectiveness of the pattern construction method proposed in this application.

[0246] The sand erosion resistance of the coating was tested using a falling sand impact tester according to the national standard GB / T 23988-2009. The test results are as follows: Figure 8 As shown. Figure 8 The curves in the figure represent the mass of the sample worn away as the total weight of the falling sand increases. The experimental results show that after 400 kg of falling sand, the sand-resistant coatings provided in this application all have a significant protective effect on the substrate compared to the uncoated substrate. Specifically, the weight loss of the sample protected by the coating in Example 1 is only 42% of that of the uncoated sample, while the weight loss of the sample protected by the coating in Example 2 is the smallest, demonstrating the best sand-resistant performance.

[0247] The contact angle test results of the sand-erosion-resistant photocurable coating prepared in Example 1 are as follows: Figure 9 As shown. From Figure 9 It can be seen that the water contact angles of the photocurable coating surfaces of the sand-resistant coatings in Examples 1-4 are 113°, 105°, 112° and 102°, respectively, which proves that the coating surfaces have low surface energy.

[0248] Although this application has been described in detail in this specification with general descriptions and specific embodiments, some modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, such modifications or improvements made without departing from the spirit of this application are all within the scope of protection claimed in this application.

Claims

1. A photocurable coating resistant to sand erosion, characterized in that, The raw materials are mixed evenly to obtain a UV-curable coating. The photocurable coating is then applied to the substrate and cured with ultraviolet light to obtain a sand-resistant photocurable coating. The raw materials, by weight, include: 5-30 parts of fluorinated polyurethane macromolecular photoinitiator; 1-5 parts of hydrogen-abstracting small molecule photoinitiator; 30-90 parts of monofunctional acrylate monomer; 10-60 parts of multifunctional acrylate crosslinking agent; 0-20 parts of diacrylate-terminated oligomers; Solvent 0~30 parts; The fluorinated polyurethane macromolecular photoinitiator is selected from any one of the following polymers: ； ； ； ； Among them, a, b, c, d, m, f, x, y, and z are each independent positive integers.

2. The photocurable coating according to claim 1, characterized in that, The fluorinated polyurethane macromolecular photoinitiator is prepared by the following method: S1, Compound 1, Compound 2 and a weak base are dissolved in an organic solvent and refluxed under an inert atmosphere; after the reaction is complete, the organic phase is collected by washing with deionized water and extraction with dichloromethane, dried and the solvent is removed by rotary evaporation to obtain the polyurethane precursor. Compound 1 is selected from any of the following chemical structures: ； Where X is a halogen; The chemical structure of compound 2 is shown in formula (2): Equation (2) The chemical structure of the polyurethane precursor is shown in formula (3): Equation (3) S2, a mixed solution is obtained by dissolving polyurethane precursor, low surface energy fluorinated prepolymer, chain extender and diisocyanate in an organic solvent; Under inert gas protection, the mixed solution is heated to carry out a polymerization reaction to obtain a polyurethane solution; The solid and liquid components in the polyurethane solution are separated using a poor solvent. The solid is collected and dried to obtain a fluorinated polyurethane macromolecular photoinitiator.

3. The photocurable coating according to claim 2, characterized in that, The weak base is any one of anhydrous potassium carbonate, anhydrous sodium carbonate, sodium bicarbonate, potassium bicarbonate, ammonia, or ammonium bicarbonate. The organic solvent is any one of tetrahydrofuran, acetone, dichloromethane, chloroform, dioxane, butanone, ethyl acetate, DMF, DMSO, toluene, ethanol, or methanol; The low surface energy fluorinated prepolymer is a C1-C30 divalent alkyl group with partially or completely substituted fluorine atoms at the end of a dihydroxyl group. Alternatively, the low surface energy fluorinated prepolymer is a C1-C30 divalent silanoxy group with partially or completely substituted fluorine atoms at the end of a dihydroxyl group. The chain extender is a dihydroxy-terminated oligomer.

4. The photocurable coating according to claim 3, characterized in that, The low surface energy fluorinated prepolymer is selected from any one of the following compounds: ； The chain extender is a polyester diol or polyether diol with a molecular weight of 500-5000. The diisocyanate is selected from any one of the following compounds: 。 5. The photocurable coating according to claim 2, characterized in that, The molar ratio of compound 1, compound 2 and the weak base is 1:2~10:2~10; The molar ratio of the polyurethane precursor, the low surface energy fluorinated prepolymer, and the chain extender is 1:1~10:0.1~1; In the polyurethane precursor, low surface energy fluorinated prepolymer, chain extender and diisocyanate system, the molar ratio of hydroxyl groups to isocyanate groups is 1:1 to 7:

6. The low surface energy segments of the fluorinated prepolymer have a molecular weight of 500-3000 g / mol.

6. The photocurable coating according to claim 1, characterized in that, The hydrogen-abstracting small molecule photoinitiator includes any one of the following compounds: 。 7. The photocurable coating according to claim 1, characterized in that, The monofunctional acrylate monomers include any one of isooctyl acrylate, isobornyl acrylate, tetrahydrofurfuryl acrylate, lauryl acrylate, benzyl acrylate, methyl methacrylate, isobornyl methacrylate, hydroxyethyl methacrylate, glycidyl methacrylate, 2-phenoxyethyl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, 4-acryloylmorpholine, cyclic trimethylolpropane formal acrylate, n-butyl acrylate, or polyethylene glycol o-phenylphenyl ether acrylate. The multifunctional acrylate crosslinking agent includes any one of 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, neopentyl glycol diacrylate, ethoxylated bisphenol A diacrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, bis(trimethylolpropane tetraacrylate) or tri(2-hydroxyethyl)isocyanurate triacrylate; The diacrylate-terminated oligomers include at least one of polyester polyurethane acrylate, polyether polyurethane acrylate, polyester acrylate, or polyether acrylate. The solvent is any one of ethyl acetate, butyl acetate, tetrahydrofuran, or ethanol.

8. The photocurable coating according to claim 1, characterized in that, The coating is applied by dripping, scraping, or spraying. The wavelength for UV curing is 254~450 nm; the light intensity is 1~10000 mW / cm². 2 Illumination time > 5 s.

9. The application of the sand-resistant photocurable coating according to any one of claims 1-8 in aircraft, wind turbine generators and high-speed rail transportation.

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