Anti-ultraviolet self-repairing coating and preparation method thereof

Abstract

The invention relates to the technical field of coatings, and discloses an anti-ultraviolet self-repairing coating and a preparation method thereof.The anti-ultraviolet self-repairing coating is prepared from, by weight, 500-550 parts of thioether resin, 50-55 parts of carbon quantum dots, 100-110 parts of microcapsules, 150-165 parts of flaky mica powder, 5-5.5 parts of wetting agent and 200-220 parts of deionized water. The carbon quantum dots are synthesized and prepared by taking waste walnut shells as a carbon source through a hydrothermal method, thioether resin is prepared by taking cardanol epoxy resin as a main body and introducing thioether bonds, and the microcapsules are prepared by taking polydopamine as a wall material and benzotriazole and castor oil triglycidyl ether as core materials, so that the coating has an excellent self-repairing effect through the synergism of the three aspects; in addition, the coating has an ultraviolet shielding effect, is anti-corrosion and anti-aging, and further prolongs the service life.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to an anti-ultraviolet self-repairing coating and a preparation method thereof. Background Art

[0002] Since the advent of modern industrial society, coatings technology has rapidly developed, becoming a vital branch of the chemical industry. It is not only widely used in the decoration and protection of building interiors and exteriors, enhancing the aesthetics and durability of living environments, but also plays a key role in numerous manufacturing sectors, including automotive, shipbuilding, aircraft, home appliances, and furniture, providing multiple functions such as corrosion and rust prevention, identification, and aesthetics. With technological advancements and growing environmental awareness, new coatings featuring low VOC (volatile organic compound) content, non-toxicity, UV protection, water-based, powdered form, and self-healing properties have gradually become mainstream in the market, satisfying people's pursuit of healthy living and sustainable development.

[0003] The development of self-healing coatings stems from the performance limitations of traditional coatings in complex application scenarios. Traditional polymer-based composite materials, such as epoxy resin coatings, are susceptible to impact and form microcracks during processing and use. Although this type of damage is difficult to see with the naked eye, it will significantly reduce the mechanical strength and service life of the material. Inspired by the self-healing mechanism of organisms, scientists proposed the concept of self-healing coatings in the 1990s, aiming to achieve autonomous repair of damage through the intelligent response mechanism inside the material. CN117417680A discloses a self-healing coating and its preparation method and application. The self-healing coating of the invention adopts component A containing epoxy resin and microcapsules and component B containing curing agent. After the two are mixed and cured, a coating with self-healing function can be obtained. When the coating resin matrix is ​​damaged, the microcapsules will rupture in time to release epoxy resin, thereby achieving self-repair of the coating. However, the curing agent of the invention is mixed with the resin emulsion and exposed to the external environment, which is prone to deterioration and failure, affecting the self-healing effect and shortening the service life of the coating. Summary of the Invention

[0004] In order to overcome the shortcomings and deficiencies of the prior art, the present invention aims to provide an anti-UV self-healing coating and a preparation method thereof. The prepared coating has excellent self-healing effect. In addition, it also has a UV shielding effect, inhibits aging, and further extends the service life of the coating.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] Disclosed is an anti-ultraviolet self-repairing coating, the raw materials of which are composed by weight of: 500-550 parts of thioether resin, 50-55 parts of carbon quantum dots, 100-110 parts of microcapsules, 150-165 parts of flaky mica powder, 5-5.5 parts of wetting agent, and 200-220 parts of deionized water.

[0007] Preferably, the sulfide resin is prepared by mixing cardanol epoxy resin and 4,4'-diaminodiphenyl disulfide.

[0008] Preferably, the carbon quantum dots are prepared from walnut shells by a hydrothermal method.

[0009] Preferably, the microcapsules are prepared by using polydopamine as the wall material and benzotriazole and castor oil triglycidyl ether as the core material.

[0010] The epoxy equivalent of the cardanol epoxy resin is 250-320 g / eq, and Cardolite NC-514 is used in the specific implementation.

[0011] The method for preparing the anti-ultraviolet self-repairing coating comprises the following steps:

[0012] S1. Mix walnut shell powder and nitric acid in a polytetrafluoroethylene reactor, seal it and place it in an oven at 170-190°C for 10-12 hours. Then cool the reaction solution and filter it with a 0.22 μm filter membrane to remove unreacted residues. Put the filtrate into a dialysis bag and dialyze it in deionized water for 42-48 hours. The dialyzed solution is adjusted to pH = 9 with ammonia water, magnetically stirred for 30-40 minutes, filtered, and freeze-dried for 20-24 hours to obtain carbon quantum dot powder;

[0013] S2, cardanol epoxy resin and 4,4'-diaminodiphenyl disulfide are mixed, and mechanically stirred at 80-85°C and 300 rpm for 3-5 hours to form a prepolymer. Then, nano zinc oxide is added and ultrasonicated for 1 hour to disperse uniformly. Then, acetone is added to adjust the viscosity to 500-800 cP at 25°C, and vacuum degassing is performed for 30-40 minutes to obtain a sulfide resin;

[0014] S3. Mix benzotriazole and castor oil triglycidyl ether, heat to 60°C to dissolve, immerse nano-SiO2 in the mixture, vacuum impregnate for 2-3 hours, centrifuge at 5000 rpm for 10-15 minutes to remove excess liquid, disperse the resulting solid in Tris buffer at pH = 8.5, add dopamine hydrochloride, shake at room temperature for 20-24 hours, centrifuge and wash three times to remove unreacted dopamine, and vacuum dry at 60°C for 12-16 hours to obtain microcapsules;

[0015] S4. Mix the sulfide bond resin and carbon quantum dots, emulsify at a high shear speed of 10,000 rpm for 1-2 hours, add microcapsules, flaky mica powder and wetting agent, and stir evenly. Grind on a three-roll mill for 3-4 times with a roller gap of 10 μm to obtain an anti-UV self-healing coating.

[0016] Preferably, the concentration of the nitric acid is 65%.

[0017] Preferably, the amount of nitric acid used is 0.5-0.6 ml / g of walnut shell powder.

[0018] Preferably, the molecular weight cut-off of the dialysis bag is 1 kDa.

[0019] Preferably, the mass ratio of the cardanol epoxy resin, 4,4'-diaminodiphenyl disulfide, and nano zinc oxide is 20-22:3-3.3:1.

[0020] Preferably, the mass ratio of the benzotriazole, castor oil triglycidyl ether, nano-SiO2, Tris buffer, and dopamine hydrochloride is 1:1-1.1:1-1.1:15-20:0.02-0.03.

[0021] Beneficial effects of the present invention:

[0022] 1. The present invention uses cardanol epoxy resin as the main body and introduces sulfide bonds RSR as dynamic covalent bonds, which have antioxidant properties and delay UV aging of the resin. When the temperature rises, the sulfide bonds reorganize to repair microcracks. In addition, microcapsules are added to the coating. When the pH is less than 4, the wall material dissolves and releases the corrosion inhibitor and repair agent inside, further repairing the cracks.

[0023] 2. The present invention uses discarded walnut shells as a carbon source and synthesizes carbon quantum dots through a hydrothermal method. The carbon quantum dots have a high absorption rate in the ultraviolet region and an excellent ultraviolet shielding effect. The electron transfer mechanism can inhibit the electrochemical corrosion of the metal substrate and extend the service life of the coating. In addition, the carbon quantum dots have a high photothermal conversion efficiency under near-infrared light irradiation, and the local temperature rises, triggering the coordinated self-repair of the sulfide bonds. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments so as to fully understand the purpose, characteristics and effects of the present invention.

[0025] The Tris buffer in the present invention is a mixed solution of tris(hydroxymethyl)aminomethane and its conjugate acid, and the pH value is adjusted to 8.5. The wetting agent used is polydimethylsiloxane.

[0026] The anti-ultraviolet self-repairing coating described in the present invention comprises, by weight, 500-550 parts of thioether resin, 50-55 parts of carbon quantum dots, 100-110 parts of microcapsules, 150-165 parts of flaky mica powder, 5-5.5 parts of wetting agent, and 200-220 parts of deionized water.

[0027] Example 1:

[0028] The raw materials of the UV-resistant self-repairing coating described in this embodiment are composed of 550 parts of thioether resin, 55 parts of carbon quantum dots, 110 parts of microcapsules, 165 parts of flaky mica powder, 5.5 parts of wetting agent BYK-345, and 220 parts of deionized water by weight.

[0029] The method for preparing a UV-resistant self-repairing coating described in this embodiment comprises the following steps:

[0030] S1. Mix walnut shell powder and nitric acid in a polytetrafluoroethylene reactor, seal it and place it in an oven at 170°C for 11 hours. Then cool the reaction solution and filter it with a 0.22μm filter membrane to remove unreacted residues. Put the filtrate into a dialysis bag and dialyze it in deionized water for 48 hours. The dialyzed solution is adjusted to pH = 9 with ammonia water, magnetically stirred for 30 minutes, filtered, and freeze-dried for 22 hours to obtain carbon quantum dot powder; wherein the amount of nitric acid used is 0.6ml / g of walnut shell powder.

[0031] S2, cardanol epoxy resin and 4,4'-diaminodiphenyl disulfide were mixed, mechanically stirred at 80°C and 300 rpm for 4 hours to form a prepolymer, and then nano-zinc oxide was added and evenly dispersed by ultrasonication for 1 hour. Then, acetone was added to adjust the viscosity to 800 cP at 25°C, and vacuum degassing was performed for 30 minutes; the mass ratio of cardanol epoxy resin, 4,4'-diaminodiphenyl disulfide, and nano-zinc oxide was 21:3.3:1.

[0032] S3. Mix benzotriazole and castor oil triglycidyl ether, heat to 60°C to dissolve, immerse nano-SiO2 in the mixture, vacuum impregnate for 2 hours, centrifuge at 5000 rpm for 12 minutes to remove excess liquid, disperse the resulting solid in Tris buffer at pH = 8.5, add dopamine hydrochloride, oscillate at room temperature for 22 hours, centrifuge and wash three times to remove unreacted dopamine, and vacuum dry at 60°C for 16 hours to obtain microcapsules; wherein the mass ratio of benzotriazole, castor oil triglycidyl ether, nano-SiO2, Tris buffer, and dopamine hydrochloride is 1:1:1.1:20:0.02.

[0033] S4. Mix the sulfide bond resin and carbon quantum dots, emulsify at a high shear speed of 10,000 rpm for 2 h, add microcapsules, flaky mica powder and wetting agent, and stir evenly. Grind on a three-roll mill for 3 times with a roller gap of 10 μm to obtain an anti-UV self-healing coating.

[0034] Example 2:

[0035] The anti-UV self-repairing coating described in this embodiment comprises, by weight, 500 parts of thioether resin, 50 parts of carbon quantum dots, 100 parts of microcapsules, 150 parts of flaky mica powder, 5 parts of wetting agent BYK-345, and 200 parts of deionized water.

[0036] The method for preparing a UV-resistant self-repairing coating described in this embodiment comprises the following steps:

[0037] S1. Mix walnut shell powder and nitric acid in a polytetrafluoroethylene reactor, seal it and place it in an oven at 180°C for 12 hours. Then cool the reaction solution and filter it with a 0.22μm filter membrane to remove unreacted residue. Put the filtrate into a dialysis bag and dialyze it in deionized water for 42 hours. The dialyzed solution is adjusted to pH = 9 with ammonia water, magnetically stirred for 35 minutes, filtered, and freeze-dried for 24 hours to obtain carbon quantum dot powder; wherein the amount of nitric acid used is 0.5ml / g of walnut shell powder.

[0038] S2, cardanol epoxy resin and 4,4'-diaminodiphenyl disulfide were mixed, mechanically stirred at 82°C and 300 rpm for 5 hours to form a prepolymer, and then nano-zinc oxide was added and evenly dispersed by ultrasonication for 1 hour. Then, acetone was added to adjust the viscosity to 500 cP at 25°C, and vacuum degassing was performed for 35 minutes; the mass ratio of cardanol epoxy resin, 4,4'-diaminodiphenyl disulfide, and nano-zinc oxide was 22:3:1.

[0039] S3. Mix benzotriazole and castor oil triglycidyl ether, heat to 60°C to dissolve, immerse nano-SiO2 in the mixture, vacuum impregnate for 2.5 hours, centrifuge at 5000 rpm for 15 minutes to remove excess liquid, disperse the resulting solid in Tris buffer at pH = 8.5, add dopamine hydrochloride, oscillate at room temperature for 20 hours, centrifuge and wash three times to remove unreacted dopamine, and vacuum dry at 60°C for 14 hours to obtain microcapsules; wherein the mass ratio of benzotriazole, castor oil triglycidyl ether, nano-SiO2, Tris buffer, and dopamine hydrochloride is 1:1.1:1:18:0.03.

[0040] S4. Mix the sulfide bond resin and carbon quantum dots, emulsify at a high shear speed of 10,000 rpm for 1 hour, add microcapsules, flaky mica powder and wetting agent, and stir evenly. Grind on a three-roll mill for 4 times with a roller gap of 10 μm to obtain an anti-UV self-healing coating.

[0041] Example 3:

[0042] S1. Walnut shell powder and nitric acid are mixed in a polytetrafluoroethylene reactor, sealed and placed in an oven at 190°C for 10 hours. The reaction solution is then cooled and filtered with a 0.22 μm filter membrane to remove unreacted residues. The filtrate is placed in a dialysis bag and dialyzed in deionized water for 45 hours. The dialyzed solution is adjusted to pH = 9 with ammonia water, magnetically stirred for 40 minutes, filtered, and freeze-dried for 20 hours to obtain carbon quantum dot powder; wherein the amount of nitric acid used is 0.55 ml / g of walnut shell powder.

[0043] S2, cardanol epoxy resin and 4,4'-diaminodiphenyl disulfide were mixed, and mechanically stirred at 85°C and 300 rpm for 3 hours to form a prepolymer. Then, nano zinc oxide was added and uniformly dispersed by ultrasonication for 1 hour. Then, acetone was added to adjust the viscosity to 750 cP at 25°C, and vacuum degassing was performed for 40 minutes. The mass ratio of cardanol epoxy resin, 4,4'-diaminodiphenyl disulfide, and nano zinc oxide was 20:3.2:1.

[0044] S3. Mix benzotriazole and castor oil triglycidyl ether, heat to 60°C to dissolve, immerse nano-SiO2 in the mixture, vacuum impregnate for 3 hours, centrifuge at 5000 rpm for 10 minutes to remove excess liquid, disperse the obtained solid in Tris buffer at pH = 8.5, add dopamine hydrochloride, oscillate at room temperature for 22 hours, centrifuge and wash three times to remove unreacted dopamine, and vacuum dry at 60°C for 16 hours to obtain microcapsules; wherein the mass ratio of benzotriazole, castor oil triglycidyl ether, nano-SiO2, Tris buffer, and dopamine hydrochloride is 1:1:1.05:20:0.02.

[0045] S4. Mix the sulfide bond resin and carbon quantum dots, emulsify at a high shear speed of 10,000 rpm for 2 hours, add microcapsules, flaky mica powder and wetting agent, stir evenly, grind on a three-roll grinder for 4 times with a roller gap of 10 μm to obtain an anti-UV self-healing coating.

[0046] Comparative Example 1:

[0047] The only difference between this comparative example and Example 1 is that carbon quantum dots were not prepared, and the remaining raw materials and steps were the same as those in Example 1.

[0048] Comparative Example 2:

[0049] The only difference between this comparative example and Example 1 is that no thioether resin is prepared, and the remaining raw materials and steps are the same as those in Example 1.

[0050] Coating performance test:

[0051] The UV transmittance at 300 nm was measured using a UV-visible spectrophotometer. The corrosion resistance was tested according to GB / T 10125, "Corrosion test in artificial atmospheres - Salt spray test." The wear resistance was tested according to GB / T 1768-2006, "Paints and varnishes - Determination of abrasion resistance - Rotating rubber grinding wheel method." The crack repair rate was calculated based on the crack repair length and depth.

[0052] Table 1: Coating performance test results

[0053] Light transmittance (%) Salt spray resistance (h) wear resistance Crack repair rate (%) Example 1 0.52 1360 Level 1 96 Example 2 0.49 1310 Level 1 95 Example 3 0.50 1280 Level 1 95 Comparative Example 1 2.36 990 Level 1 78 Comparative Example 2 0.48 1290 Level 1 65

[0054] As can be seen from the table above, Example 1 exhibits lower transmittance, better salt spray resistance, and a higher crack repair rate compared to Comparative Example 1. This is because the carbon quantum dots prepared in Example 1 have high UV absorption, excellent UV shielding, and inhibit electrochemical corrosion of the metal substrate through an electron transfer mechanism, extending the coating's service life. Furthermore, the carbon quantum dots have high photothermal conversion efficiency under near-infrared light irradiation, which increases local temperature and triggers synergistic self-repair of sulfide bonds. The higher crack repair rate in Example 1 compared to Comparative Example 2 is due to the sulfide resin prepared in Example 1, which, when heated, reorganizes sulfide bonds to repair microcracks.

[0055] The above embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work shall fall within the scope of protection of the present invention.

Claims

1. An anti-ultraviolet self-repairing coating, characterized in that: The raw materials include, by weight, 500-550 parts of thioether resin, 50-55 parts of carbon quantum dots, 100-110 parts of microcapsules, 150-165 parts of flaky mica powder, 5-5.5 parts of wetting agent, and 200-220 parts of deionized water.

2. The anti-ultraviolet self-repairing coating according to claim 1, characterized in that: The sulfide resin is prepared by mixing cardanol epoxy resin and 4,4'-diaminodiphenyl disulfide.

3. The anti-ultraviolet self-repairing coating according to claim 1, characterized in that: The carbon quantum dots are prepared from walnut shells through a hydrothermal method.

4. The anti-ultraviolet self-repairing coating according to claim 1, characterized in that: The microcapsules are prepared by taking polydopamine as the wall material and benzotriazole and castor oil triglycidyl ether as the core materials.

5. The method for preparing an anti-ultraviolet self-repairing coating according to any one of claims 1 to 4, characterized in that the steps include: S1. Mix walnut shell powder and nitric acid in a polytetrafluoroethylene reactor, seal it and place it in an oven at 170-190°C for 10-12 hours. Then cool the reaction solution and filter it with a 0.22 μm filter membrane to remove unreacted residues. Put the filtrate into a dialysis bag and dialyze it in deionized water for 42-48 hours. The dialyzed solution is adjusted to pH = 9 with ammonia water, magnetically stirred for 30-40 minutes, filtered, and freeze-dried for 20-24 hours to obtain carbon quantum dot powder; S2, cardanol epoxy resin and 4,4'-diaminodiphenyl disulfide are mixed, and mechanically stirred at 80-85°C and 300 rpm for 3-5 hours to form a prepolymer. Then, nano zinc oxide is added and ultrasonicated for 1 hour to disperse uniformly. Then, acetone is added to adjust the viscosity to 500-800 cP at 25°C, and vacuum degassing is performed for 30-40 minutes to obtain a sulfide resin; S3. Mix benzotriazole and castor oil triglycidyl ether, heat to 60°C to dissolve, immerse nano-SiO2 in the mixture, vacuum impregnate for 2-3 hours, centrifuge at 5000 rpm for 10-15 minutes to remove excess liquid, disperse the resulting solid in Tris buffer at pH = 8.5, add dopamine hydrochloride, shake at room temperature for 20-24 hours, centrifuge and wash three times to remove unreacted dopamine, and vacuum dry at 60°C for 12-16 hours to obtain microcapsules; S4. Mix the sulfide bond resin and carbon quantum dots, emulsify at a high shear speed of 10,000 rpm for 1-2 hours, add microcapsules, flaky mica powder and wetting agent, and stir evenly. Grind on a three-roll mill for 3-4 times with a roller gap of 10 μm to obtain an anti-UV self-healing coating.

6. The method for preparing an anti-ultraviolet self-repairing coating according to claim 5, characterized in that: The concentration of the nitric acid is 65%.

7. The method for preparing an anti-ultraviolet self-repairing coating according to claim 5, characterized in that: The amount of nitric acid used is 0.5-0.6 ml / g of walnut shell powder.

8. The method for preparing an anti-ultraviolet self-repairing coating according to claim 5, characterized in that: The molecular weight cut-off of the dialysis bag is 1 kDa.

9. The method for preparing an anti-ultraviolet self-repairing coating according to claim 5, characterized in that: The mass ratio of the cardanol epoxy resin, 4,4'-diaminodiphenyl disulfide and nano zinc oxide is 20-22:3-3.3:

1.

10. The method for preparing an anti-ultraviolet self-repairing coating according to claim 5, characterized in that: The mass ratio of the benzotriazole, castor oil triglycidyl ether, nano-SiO2, Tris buffer and dopamine hydrochloride is 1:1-1.1:1-1.1:15-20:0.02-0.03.