Self-repairing type UV curing alumite color layer coating and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials, and particularly provides a self-repairing type UV curing alumite color layer coating and a preparation method thereof. The water-based ink is prepared from, by weight, 30-50 parts of polyurethane acrylic resin, 10-25 parts of modified acrylic oligomer containing dynamic covalent bonds, 2-5 parts of photoinitiator, 3-8 parts of hydrophobic modified nano filler and 1-3 parts of cross-linking agent, and the dynamic covalent bonds are selected from at least one of hydrazide bonds, boric acid ester bonds and Diels-Alder bonds. By introducing a gradient energy collaborative network of dynamic covalent bonds and quadruple hydrogen bonds, rapid self-repairing of the coating at normal temperature and thermal triggering recombination of deep damage are achieved, and meanwhile through the micro-phase separation design of the hydrophobic core-shell filler and the graft modified silicon carbide nanowires, the hydrolysis resistance is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a self-healing UV-curable aluminized chromatic layer coating and a preparation method thereof. Background Art

[0002] In recent years, UV-curable coatings have been widely used in the field of aluminized chromatic layer coating due to advantages such as rapid curing and low VOC emissions. However, there is a contradiction between the coating hardness and self-healing performance of traditional UV coatings: although the high cross-linking degree system has excellent wear resistance, the molecular chain movement is restricted, and the scratch repair efficiency is insufficient. Especially in the scenario of aluminized stamping, the coating needs to withstand mechanical stresses such as die pressing and gilding. The traditional coating is prone to deterioration of the optical effect due to the propagation of microcracks and cannot be effectively repaired by conventional heating.

[0003] Existing self-healing UV coatings mostly rely on a single dynamic bond (such as hydrogen bond or disulfide bond), and there are significant limitations. For example, the polyurethane acrylate system achieves repair through elastic recovery, but it requires high temperature (>80°C) or long time (>2 hours) stimulation, and the mechanical strength decreases by more than 30% after repair. The dynamic covalent bonds (such as acylhydrazone bond, borate bond) in the aqueous system are easily eroded by moisture, and the hydrolysis rate reaches 40%-50% in a high humidity environment, resulting in the failure of the repair network. In addition, it is difficult for the existing technology to balance the coating denseness and molecular chain mobility: although the high cross-linking degree UV-curable network improves the scratch resistance, it hinders the recombination of dynamic bonds, resulting in low repair efficiency.

[0004] To break through the above bottleneck, some technicians in the field have proposed a dynamic bond coordination strategy. For example, introducing a gradient energy network of metal coordination bonds and hydrogen bonds can achieve rapid repair at room temperature and maintain high hardness. However, the hydrolysis stability of dynamic bonds in the aqueous system still needs to be optimized: the existing hydrophobic modification schemes (such as fluorine / silicon-containing resins) lead to a decrease in coating adhesion and poor compatibility with the UV-curing process. Therefore, developing a waterborne self-healing UV coating with both hydrolysis resistance, high repair efficiency and process adaptability has become a technical problem to be solved urgently in the field of aluminized chromatic layer protection. Summary of the Invention

[0005] In view of this, the present invention proposes a self-healing UV-curable aluminized chromatic layer coating and a preparation method thereof.

[0006] The technical solution of the present invention is realized as follows: The present invention provides a self-healing UV-curable aluminized chromatic layer coating, which includes the following components by weight:

[0007] 30-50 parts of polyurethane acrylate resin

[0008] 10-25 parts of modified acrylic oligomer containing dynamic covalent bonds

[0009] 2 - 5 parts of photoinitiator

[0010] 3 - 8 parts of hydrophobically modified nano - filler

[0011] 1 - 3 parts of cross - linker

[0012] The dynamic covalent bond is selected from at least one of hydrazide bond, borate ester bond and Diels - Alder bond.

[0013] In some embodiments, the dynamic covalent bond is a hydrazide bond. The modified acrylic oligomer containing the dynamic covalent bond is formed by the reaction of an acrylic oligomer containing a hydrazide group with an aldehyde - modified acrylic resin. Among them, the molar ratio of the acrylic oligomer containing a hydrazide group to the aldehyde - modified acrylic resin is 1:1 - 1.2, and a hydrazide bond is formed by a condensation reaction in an acetic acid buffer solution with a pH of 4.5 - 5.0.

[0014] The specific reaction conditions are as follows: Mix the acrylic oligomer containing a hydrazide group and the aldehyde - modified acrylic resin at a molar ratio of 1:1 - 1.2, and stir - react at 60 °C for 4 - 6 hours in an acetic acid buffer solution (pH 4.5). Add 0.1 - 0.5 wt% of a carboxylic acid catalyst (such as p - toluenesulfonic acid) to accelerate the condensation reaction. Adjust the cross - link density by controlling the reaction time so that the dynamic bond density reaches 5 - 15 mol% to balance the mechanical strength and repair efficiency. After the reaction, remove the unreacted substances by centrifugation and freeze - dry to obtain the modified acrylic oligomer containing dynamic hydrazide bonds, and its glass transition temperature (Tg) can be adjusted to - 20 °C to 50 °C by the dynamic bond density.

[0015] The acrylic oligomer containing a hydrazide group is prepared by the following steps:

[0016] Using methyl acrylate and butyl acrylate as monomers (molar ratio (3 - 5):1), add azobisisobutyronitrile as an initiator (0.5 - 2 wt%), and carry out a free - radical polymerization reaction at 60 - 80 °C for 4 - 6 hours under nitrogen protection;

[0017] Stir the polymerization product and hydrazine hydrate (molar ratio 1:(3 - 5)) at room temperature for 8 - 12 hours, and introduce a hydrazide group (-CONHNH 2 ) through an ester - group substitution reaction, and then dialyze with a 3K dialysis bag for 2 - 3 days and freeze - dry to obtain it.

[0018] The aldehyde - modified acrylic resin is prepared by the following steps:

[0019] Copolymerize 2 - hydroxyethyl acrylate and butyl acrylate (molar ratio 1:4), add an initiator (0.2 - 1 wt%), and react at 60 °C for 6 - 8 h to generate a hydroxyl - containing acrylic resin;

[0020] Using sodium periodate (NaIO 4 ), oxidize the hydroxyl group to an aldehyde group (-CHO) under the condition of pH 4 - 5, and the mass fraction of the aldehyde group is ≥8%;

[0021] In some embodiments, the dynamic covalent bond system further includes a quadruple hydrogen bond network as an auxiliary repair mechanism. The quadruple hydrogen bond network is formed by copolymerizing and introducing ureidopyrimidinone-functionalized acrylic monomers, and the monomers account for 5 - 15% of the total mass of the modified acrylic oligomer.

[0022] UPy groups can form a strong reversible network through quadruple hydrogen bonds (bond energy ≈40 kJ / mol), and its dissociation temperature (Td ≈80 °C) is higher than room temperature but lower than the breaking temperature of dynamic covalent bonds (such as hydrazide bonds), realizing hierarchical repair.

[0023] The quadruple hydrogen bond network repairs microcracks through rapid dissociation - recombination at room temperature, while deep damage requires heat treatment at 60 - 80 °C to trigger the rearrangement of hydrazide bonds, and the two form an energy gradient response. The double bond reactivity of UPy monomers is close to that of acrylate monomers, and the copolymer sequence distribution is uniform.

[0024] In some embodiments, the hydrophobic modified nano-filler is a core-shell structure particle with silica as the core and polytetrafluoroethylene as the shell, where the thickness of the polytetrafluoroethylene shell layer is 5 - 20 nm, and the particle size range is 50 - 200 nm.

[0025] In the above embodiments, the silica core material can be prepared by the sol-gel method. Using tetraethyl orthosilicate as the silicon source and ammonia water as the catalyst, hydrolysis and condensation occur in an ethanol / water mixed solvent at 25 - 40 °C to generate monodisperse SiO 2 nano-particles, and the core size is controlled by adjusting the TEOS concentration (0.1 - 0.5 mol / L) and reaction time (2 - 6 hours).

[0026] The coating process of the shell includes: coating a PTFE shell layer on the surface of SiO 2 by emulsion polymerization: dispersing SiO 2 in an emulsion containing fluorine monomers (tetrafluoroethylene, TFE), adding ammonium perfluorooctanoate (PFOA) as an emulsifier and ammonium persulfate (APS) as an initiator, and reacting at 70 - 90 °C and a pressure of 0.5 - 1.0 MPa for 2 - 4 hours. By adjusting the TFE monomer concentration (5 - 20 wt%) and reaction time (1 - 3 hours), the thickness of the PTFE shell layer is 5 - 20 nm.

[0027] The PTFE shell layer blocks the penetration of water molecules, and SiO 2The hard core enhances the hardness of the coating through the physical anchoring effect. The low surface energy of the PTFE shell drives it to form hydrophobic microdomains in the resin matrix, forming a microphase separation structure with hydrophilic soft segments and promoting the self-healing response of the dynamic bond network.

[0028] In some embodiments, the photoinitiator is a composite system of diphenylphosphine oxide and 1-hydroxycyclohexyl phenyl ketone, and the mass ratio of diphenylphosphine oxide to 1-hydroxycyclohexyl phenyl ketone is 1:2 - 1:4.

[0029] In some embodiments, it further includes 0.5 - 2 parts of silicon carbide nanowires. After the silicon carbide nanowires are activated by plasma, a grafting layer is formed through a free radical grafting reaction with maleic anhydride-styrene monomers in the presence of an initiator, and the grafting rate is 10 - 30%.

[0030] The diameter of the silicon carbide nanowires is 50 - 100 nm, the length is 5 - 20 μm, and the specific surface area ≥ 20 m 2 / g. The plasma activation conditions include: treating with Ar plasma (power 50 - 100 W, treatment time 5 - 10 minutes, gas pressure 10 - 30 Pa), generating active sites on the surface of the nanowires, and detecting that the surface oxygen content is increased to 15 - 25 at% by XPS.

[0031] Reaction system:

[0032] The molar ratio of maleic anhydride to styrene is 1:(1 - 3). It is dissolved in xylene (solid content 5 - 10 wt%), and 0.5 - 2 wt% of benzoyl peroxide is added.

[0033] Reaction conditions:

[0034] Under nitrogen protection, react at 70 - 90 °C for 4 - 8 h. After the reaction is completed, centrifuge at 8000 rpm for 15 min, wash three times with acetone and ethanol in sequence, and vacuum dry at 60 °C for 12 h.

[0035] The hydrophobic benzene ring and ester groups of the maleic anhydride-styrene copolymer form a physical barrier to inhibit water molecules from penetrating into the dynamic bond network, and the dynamic bond retention rate is increased after 240-hour damp heat aging. The polar ester groups in the grafting layer form hydrogen bonds with the resin matrix, improving the nanowire dispersion and stress transfer efficiency.

[0036] A composite system of epoxy group siloxane, and the compounding ratio of trimethylolpropane triacrylate to epoxy group siloxane is 3:1 - 5:1, which is used to realize the thermal-triggered dynamic bond recombination after UV curing.

[0037] In some embodiments, it further includes 0.1 - 1 part of pigment particles.

[0038] The second aspect of the present invention also provides a method for preparing the above self-healing UV-curable aluminized color layer coating, comprising the following steps:

[0039] Step 1: Stir and emulsify polyurethane acrylate resin and dynamically covalently bonded modified acrylic oligomer at 60 - 80 °C and a rotation speed of 500 - 1000 rpm for 30 - 60 minutes;

[0040] Step 2: Add hydrophobically modified nano-fillers and ultrasonically disperse for 30 - 60 minutes;

[0041] Step 3: Sequentially add a photoinitiator, a crosslinking agent, and other additives, and stir until the viscosity of the system reaches 2000 - 5000 mPa·s;

[0042] Step 4: Coating on the aluminized base film by a doctor blade or spraying process and perform UV curing, and the UV curing energy is 300 - 500 mJ / cm 2 .

[0043] In some embodiments, after UV curing in Step 4, heat treatment is performed at 60 - 80 °C for 1 - 3 minutes to activate the dynamic bond repair function.

[0044] The present invention has the following beneficial effects compared with the prior art:

[0045] By introducing a gradient energy synergy network of dynamic covalent bonds and quadruple hydrogen bonds, the present invention realizes rapid self-healing of the coating at room temperature and thermal-triggered recombination of deep damage. At the same time, through the microphase separation design of hydrophobic core-shell fillers and graft-modified silicon carbide nanowires, the hydrolysis resistance is improved. Combining the photoinitiator complex system and the crosslinking agent thermal activation process, on the basis of maintaining high hardness and excellent adhesion, the contradiction between high crosslinking degree and self-healing performance in traditional UV coatings is solved, taking into account the mechanical tolerance and environmental adaptability in the aluminized stamping scenario, and significantly expanding the application potential in high-end packaging, electronic devices and other fields. Specific Embodiments

[0046] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of the present invention belong. If the definitions stated in this section are contrary to or otherwise inconsistent with the definitions stated in the patents, patent applications, published patent applications, and other publications incorporated herein by reference, the definitions listed in this section shall prevail over the definitions incorporated herein by reference.

[0048] Unless otherwise specified, the methods used in the following embodiments are all conventional methods. The materials, reagents, and instruments used, unless otherwise specified, are all conventional materials, reagents, and instruments in this field, and those skilled in the art can obtain them through commercial channels.

[0049] When an equivalent, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values, it should be understood that all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value are specifically disclosed, regardless of whether the ranges are separately disclosed. For example, when the range "1 to 5" is disclosed, the described range should be interpreted to include ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range. In the specification and claims of this application, range limitations can be combined and / or interchanged, and if not otherwise stated, these ranges include all sub-ranges contained therein.

[0050] Example 1

[0051] Raw material ratio:

[0052] Polyurethane acrylate resin: 40 g

[0053] Hydrazide bond modified acrylic oligomer (dynamic bond density 12 mol%): 18 g

[0054] Diphenylphosphine oxide: Photoinitiator with a mass ratio of 1-hydroxycyclohexylbenzoate of 3:1: 3 g

[0055] Core-shell structure particles with silica as the core and polytetrafluoroethylene as the shell (particle size 120 nm, PTFE shell layer 12 nm): 5 g

[0056] TMPTA: Crosslinking agent with a mass ratio of epoxy group siloxane of 4:1: 2 g

[0057] Silicon carbide nanowires (grafting rate 22%): 1.5 g

[0058] Pigment particles: 0.5 g

[0059] Among the following raw materials, UPy-methyl acrylate can be synthesized by the following method:

[0060] Dissolve 10 g of UPy-OH and 26.6 g of IPDI in 100 ml of anhydrous THF. Under a nitrogen atmosphere, add 36 mg of DBTDL and heat to 60 °C. React for 4 h to form UPy-NCO. Then dissolve 20 g of UPy-NCO and 6.5 g of HEA in 50 ml of THF, add 13 mg of DBTDL, and react at 60 °C for 6 h. Perform silica gel column chromatography (eluent: ethyl acetate / petroleum ether = 1:3), collect the target fraction, and dry to obtain UPy-methyl acrylate.

[0061] Preparation steps:

[0062] Step 1: Preparation of hydrazide group-modified acrylic oligomer:

[0063] The molar ratio of methyl acrylate to butyl acrylate is 4:1. Add 1 wt% of AIBN and polymerize at 70 °C for 5 h under a nitrogen atmosphere to obtain an acrylic oligomer (Mn = 3200 Da, PDI = 1.3). React the acrylic oligomer with hydrazine hydrate at a molar ratio of 1:4 and stir at 25 °C for 10 h. Then dialyze with a 3K dialysis bag and freeze-dry to obtain a hydrazide oligomer (the substitution rate of the hydrazide group detected by FTIR is 85%). In methyl acrylate, 10 wt% of UPy-methyl acrylate is contained.

[0064] Step 2: Preparation of aldehyde group-modified acrylic resin:

[0065] Hydroxyethyl acrylate and butyl acrylate are copolymerized at a molar ratio of 1:4. Add 0.5 wt% of APS and react at 60 °C for 7 h to obtain a hydroxylated resin. Add 1.3 times the molar amount of NaIO 4 , react at pH 4.5 and 30 °C in the dark for 3 h, and the aldehyde group content measured by NMR is 9.2%.

[0066] Step 3: Synthesis of dynamic bond oligomer:

[0067] Mix the products of Step 1 and Step 2 at a molar ratio of 1:1.1, add 0.3 wt% of p-toluenesulfonic acid, react at pH 4.8 and 60 °C for 5 h, and after centrifugal purification, the dynamic bond density measured by DMA is 12 mol%.

[0068] Step 4: Coating preparation:

[0069] Stir and emulsify polyurethane acrylate resin and hydrazide group-modified acrylic oligomer at 70 °C and 800 rpm for 40 min;

[0070] Add core-shell structure particles with silica as the core and polytetrafluoroethylene as the shell and ultrasonically disperse for 40 min;

[0071] The photoinitiator, crosslinking agent and pigment particles were added successively and stirred until the system viscosity reached 3000 mPa·s;

[0072] The coating was applied to the surface of the electroaluminum base film by knife coating, and then irradiated with UV light at 400 mJ / cm 2 for UV curing, and then heat-treated at 70 °C for 2 min.

[0073] Example 2

[0074] In this example, based on Example 1, the core-shell structure particles and grafted nanowires were omitted.

[0075] Example 3

[0076] In this example, based on Example 1, the grafted nanowires were replaced with ungrafted nanowires.

[0077] Example 4

[0078] In this example, based on Example 1, a photoinitiator with a mass ratio of diphenylphosphine oxide to 1-hydroxycyclohexyl phenyl ketone of 1:2 was used.

[0079] Example 5

[0080] In this example, based on Example 1, the photoinitiator used was a single diphenylphosphine oxide.

[0081] Example 6

[0082] In this example, based on Example 1, the photoinitiator used was 1-hydroxycyclohexyl phenyl ketone.

[0083] The performance of the chromatic layer coatings prepared in the above different examples was tested:

[0084] Self-healing efficiency:

[0085] A scratch with a depth of 2 μm and a width of 10 μm was made on the coating surface using a nanoindentation instrument (Hysitron TI 950).

[0086] Parameters: load 50 mN, loading rate 0.5 mN / s.

[0087] Ambient temperature repair: Standing at 25 °C for 1 hour.

[0088] Thermal trigger repair: Heat treatment at 80 °C for 3 minutes.

[0089] The scratch volume recovery rate was measured by a laser confocal microscope (Keyence VK-X1000).

[0090] Hydrolysis resistance test:

[0091] In a thermostatic and humidistatic chamber (85% RH, 60°C), the test time is 240 hours

[0092] The characteristic peak (1640 cm -1 ) area change of the hydrazide bond was analyzed by Fourier transform infrared spectroscopy (FTIR, Nicolet iS50).

[0093] Mechanical property test:

[0094] Tested according to ASTM D3363 standard using a Mitsubishi pencil hardness tester (load 750 g).

[0095] Cross-cut method (ASTM D3359), tool spacing 1 mm, evaluate the peeling grade (0B - 5B).

[0096] Universal material testing machine (Instron 5967), tensile rate 10 mm / min, specimen size according to ISO 527 - 2 standard.

[0097] The test results are shown in the following table:

[0098] Example Normal temperature self-healing efficiency Thermally triggered self-healing efficiency Retention rate of hydrazide bond Pencil hardness Tensile strength 1 92％ 95％ 89％ 9H 25 MPa 2 85％ 88％ 65％ 7H 18 MPa 3 75％ 80％ 72％ 6H 15 MPa 4 87％ 90％ 78％ 8H 22 MPa 5 70％ 75％ 60％ 6H 14 MPa 6 68％ 73％ 58％ 5H 12 MPa

[0099] The normal temperature repair rate of Example 1 is significantly higher than that of Example 2. The core - shell particles block moisture through the hydrophobic shell layer to protect the integrity of the dynamic bond network; the grafted nanowires enhance the interfacial bonding force and avoid stress concentration. The two work together to increase the repair rate by 8%.

[0100] The retention rate of the hydrazide bond in Example 1 is much higher than that in Example 2. The PTFE shell layer reduces the water molecule permeability, and the grafted nanowires fill the interfacial micropores to form a physical barrier.

[0101] The pencil hardness of Example 1 is much higher than that of Example 3. The un - grafted nanowires cause stress concentration due to poor interfacial compatibility, damaging the continuity of the dynamic network. The grafting treatment enhances the nanowire - matrix bonding force through chemical bonds.

[0102] Example 1 uses diphenylphosphine oxide and 1 - hydroxycyclohexyl methyl ketone (3:1), and the photo - initiation depth matches the dynamic bond density (12 mol%) best, with a repair rate of 92%. While in Example 4 (1:2), due to insufficient deep - layer curing, the dynamic bond density decreases, and the repair rate drops to 87%.

[0103] When the proportion of the photo - initiator deviates from 3:1, incomplete curing leads to an increase in porosity, and the hydrolysis resistance and mechanical strength decrease sharply.

[0104] The above - mentioned is only the preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A self-repairing UV-curing electrochemical aluminum color coating, characterized in that: Calculated by weight, it includes the following components: Polyurethane acrylic resin 30-50 parts 10-25 parts of modified acrylic acid oligomer containing dynamic covalent bonds Photoinitiator 2-5 parts 3-8 parts of hydrophobically modified nanofiller Crosslinking agent 1-3 parts The dynamic covalent bond is selected from at least one of a hydrazide bond, a borate bond and a Diels-Alder bond.

2. The self-repairing UV-curing electrochemical aluminum color layer coating according to claim 1, characterized in that: The dynamic covalent bond is a hydrazide bond, and the modified acrylic oligomer containing the dynamic covalent bond is formed by reacting an acrylic oligomer containing a hydrazide group with an aldehyde-modified acrylic resin, wherein the molar ratio of the acrylic oligomer containing a hydrazide group to the aldehyde-modified acrylic resin is 1:1-1.2, and a condensation reaction is performed in an acetic acid buffer solution with a pH of 4.5-5.0 to form a hydrazide bond.

3. The self-repairing UV-curing electrochemical aluminum color layer coating according to claim 2, characterized in that: The dynamic covalent bond system also includes a quadruple hydrogen bond network as an auxiliary repair mechanism, and the quadruple hydrogen bond network is formed by copolymerizing and introducing ureidopyrimidone functionalized acrylic monomers, and the monomers account for 5-15% of the total mass of the modified acrylic oligomer.

4. The self-repairing UV-curing electrochemical aluminum color layer coating according to claim 1, characterized in that: The hydrophobically modified nanofiller is a core-shell structure particle with silicon dioxide as the core and polytetrafluoroethylene as the shell, wherein the thickness of the polytetrafluoroethylene shell layer is 5-20nm and the particle size ranges from 50-200nm.

5. The self-repairing UV-curing electrochemical aluminum color layer coating according to claim 1, characterized in that: The photoinitiator is a composite system of diphenylphosphine oxide and 1-hydroxycyclohexyl phenyl ketone, and the mass ratio of diphenylphosphine oxide to 1-hydroxycyclohexyl phenyl ketone is 1:2-1:

4.

6. The self-repairing UV-curing electrochemical aluminum color layer coating according to claim 1, characterized in that: It also includes 0.5-2 parts of silicon carbide nanowires. After being activated by plasma, the silicon carbide nanowires react with maleic anhydride-styrene monomers in the presence of an initiator through free radical grafting to form a graft layer, and the grafting rate is 10-30%.

7. The self-repairing UV-curing electrochemical aluminum color layer coating according to claim 1, characterized in that: The crosslinking agent is a compound system of trimethylolpropane triacrylate and epoxysiloxane, and the compound ratio of trimethylolpropane triacrylate to epoxysiloxane is 3:1-5:1, which is used to achieve thermally triggered dynamic bond recombination after UV curing.

8. The self-repairing UV-curing electrochemical aluminum color layer coating according to claim 1, characterized in that: Also includes 0.1-1 part of pigment particles.

9. The method for preparing the self-repairing UV-curing electrochemical aluminum color layer coating according to any one of claims 1 to 8, characterized in that: The steps include: Step 1, stirring and emulsifying the polyurethane acrylic resin and the dynamic covalent bond modified acrylic oligomer at 60-80° C. and 500-1000 rpm for 30-60 minutes; Step 2: Add hydrophobically modified nanofiller and disperse by ultrasonic for 30-60 minutes; Step 3: Add photoinitiator, crosslinking agent and other additives in sequence, and stir until the system viscosity reaches 2000-5000mPa·s; Step 4: Apply to the electrochemical aluminum base film by scraping or spraying for UV curing. The UV curing energy is 300-500mJ / cm 2 .

10. The method for preparing the self-repairing UV-curing electrochemical aluminum color layer coating according to claim 9, characterized in that: After UV curing in step 4, heat treatment is performed at 60-80°C for 1-3 minutes to activate the dynamic bond repair function.