A UV-resistant self-repairing colorful coating material and its preparation process

Abstract

The present invention discloses an anti-ultraviolet self-repairing colorful coating material and its preparation process, which relates to the technical field of coating materials. The anti-ultraviolet self-repairing colorful coating material comprises the following raw materials, calculated based on 100 parts by mass: 35-40 parts of photochromic resin, 30-35 parts of base resin, 10-15 parts of modified titanium dioxide, 1-2 parts of auxiliary agent, and the rest are solvents; the specific steps are: S1: stirring the raw materials evenly, vacuum degassing treatment, and obtaining an anti-ultraviolet self-repairing colorful coating; S2: coating the anti-ultraviolet self-repairing colorful coating on the surface of the substrate, drying, and curing to obtain an anti-ultraviolet self-repairing colorful coating material; the present invention prepares coumarin polyester based on coumarin derivatives and further introduces acrylic acid modification to obtain a self-repairing photochromic resin, and adds modified nano titanium dioxide to provide basic anti-ultraviolet performance, thereby improving the photochromic performance and self-repairing performance of the coating material.

Description

Technical Field

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

[0002] Colorful coatings, with their unique color effects and visual appeal, are valuable in decoration, display, and anti-counterfeiting applications. This effect is typically achieved by adding large amounts of photochromic agents to the coating. However, this also presents challenges, such as poor dispersion and abrasion resistance, making the coating susceptible to damage, resulting in a poor viewing experience. Furthermore, the photochromic effect is poorly reversible, and the color change tends to lose its effectiveness over time. Therefore, improving the self-healing and photochromic properties of colorful coatings is crucial.

[0003] In summary, it is of great significance to solve the above problems and prepare an anti-UV self-repairing colorful coating material. Summary of the Invention

[0004] The purpose of the present invention is to provide an anti-ultraviolet self-repairing colorful coating material and a preparation process thereof to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A UV-resistant self-repairing colorful coating material comprises the following raw materials, based on 100 parts by mass: 35-40 parts of photochromic resin, 30-35 parts of base resin, 10-15 parts of modified titanium dioxide, 1-2 parts of auxiliary agent, and the rest being solvent.

[0007] Preferably, the preparation method of the photochromic resin comprises the following steps: (1) uniformly mixing a coumarin derivative, dipropylene glycol and isophthalic acid, adding p-toluenesulfonic acid, stirring under reflux at 180-185°C for 40-60 min, gradually heating to 205-210°C, continuing stirring for 1-2 h, cooling to 100-105°C, sequentially adding maleic anhydride, methyl propylene glycol, adipic acid and polycarbonate diol, stirring at 120-125°C for 40-60 min, continuing heating to 205-210°C and stirring for 1-2 h, vacuuming for 30 min, reducing the temperature to 130-150°C, adding 0.01-0.02 wt% of hydroquinone, and cooling to room temperature to obtain a coumarin polyester;

[0008] (2) The coumarin polyester was heated to 120-130°C, 1-1.5 wt% of azobisisobutyronitrile and acrylic acid monomer were added, and the mixture was refluxed and stirred at 170-185°C for 5-7 h, cooled to 40-50°C, neutralized, and cooled to room temperature to obtain a photochromic resin.

[0009] Preferably, the coumarin polyester comprises the following raw materials in parts by mass: 9 to 11 parts of coumarin derivatives, 7 to 8 parts of dipropylene glycol, 14 to 15 parts of isophthalic acid, 2 to 2.2 parts of maleic anhydride, 1.6 to 1.7 parts of methylpropylene glycol, 0.8 to 1.2 parts of adipic acid, and 0.8 to 1.2 parts of polycarbonate diol.

[0010] Preferably, the preparation method of the coumarin derivative comprises the following steps: 4,7-dihydroxycoumarin, potassium carbonate, 3-bromo-1-propanol, and 18-crown ether-6 are sequentially added to anhydrous acetone and stirred evenly; refluxed at 55-60° C. under microwave conditions and stirred for 40 minutes; the solvent is removed under reduced pressure; purified; and dried to obtain the coumarin derivative.

[0011] Preferably, the coumarin derivative comprises the following raw materials, calculated by mass: 0.9-1.1 parts of 4,7-dihydroxycoumarin, 2-2.5 parts of potassium carbonate, 1.4-1.6 parts of 3-bromo-1-propanol, 0.65-0.75 parts of 18-crown ether-6, and 15-20 parts of anhydrous acetone.

[0012] Preferably, the mass ratio of the coumarin polyester to the acrylic acid monomer is 1:0.5-0.6;

[0013] The acrylic monomer comprises the following raw materials, calculated by mass: 15-20 parts of acrylic acid, 10-15 parts of acrylamide, 3-5 parts of 2-methacryloyloxyethyltrimethylammonium chloride, 15-20 parts of ethyl 2-hydroxymethylacrylate, and 40-50 parts of methyl methacrylate.

[0014] Preferably, the preparation method of the modified titanium dioxide comprises the following steps: (1) adding nano titanium dioxide and 3-(2,3-epoxypropoxy)propyltrimethoxysilane to a 60-70% ethanol solution and uniformly dispersing them by ultrasonication, stirring at 40-50° C. for 3-4 hours, filtering, washing, and drying to obtain epoxy-modified nano titanium dioxide;

[0015] (2) Add epoxy nano-titanium dioxide into anhydrous acetone and disperse it evenly by ultrasonication. Then add coumarin derivatives and potassium hydroxide. Stir at 80-90°C for 3-4 hours. Filter, wash and dry to obtain modified nano-titanium dioxide.

[0016] Preferably, the mass ratio of the nano-titanium dioxide to 3-(2,3-epoxypropyloxy)propyltrimethoxysilane is 1:0.3-0.4;

[0017] The modified nano titanium dioxide comprises the following raw materials, calculated by mass: 2 to 3 parts of epoxy nano titanium dioxide, 2 to 2.5 parts of coumarin derivatives, and 1 to 1.5 parts of potassium hydroxide.

[0018] Preferably, the auxiliary agent includes a leveling agent and an antioxidant in a mass ratio of 0.4 to 0.5:1; the solvent is toluene; and the base resin includes one or both of polyurethane and epoxy resin.

[0019] More preferably, the preparation process of the anti-ultraviolet self-repairing colorful coating material comprises the following steps:

[0020] S1: Add photochromic resin, base resin, anti-ultraviolet agent, and additives to the solvent in sequence and stir evenly. Each stirring time is 20-30 minutes and the stirring speed is 400-500 r / min. After the addition is completed, shear stirring is performed for 1-2 hours, and vacuum degassing is performed to obtain an anti-ultraviolet self-repairing colorful coating;

[0021] S2: coating the anti-ultraviolet self-repairing colorful coating on the surface of the substrate, drying, and curing at 130-170° C. for 2-3 hours to obtain an anti-ultraviolet self-repairing colorful coating material;

[0022] The coating thickness is 50~80μm.

[0023] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present application prepares coumarin polyester based on coumarin derivatives and further introduces acrylic acid modification to obtain a self-repairing photochromic resin. At the same time, the addition of modified nano-titanium dioxide provides basic UV resistance and further improves the self-repairing performance.

[0024] Among them, the preparation method of coumarin derivatives is to use 4,7-dihydroxycoumarin and 3-bromo-1-propanol for alkylation under the catalysis of potassium carbonate and 18-crown ether-6 to form a coumarin derivative containing two alcoholic hydroxyl groups; and the coumarin polyester is based on the coumarin derivative as a reaction monomer, copolymerized with dipropylene glycol and isophthalic acid, and functionally modified by introducing maleic anhydride methylpropylene glycol, adipic acid, and polycarbonate diol to obtain unsaturated coumarin polyester; further, the unsaturated bonds in the polyester are used to introduce acrylic acid, acrylamide, 2-methacryloyloxyethyltrimethylammonium chloride, 2-hydroxymethylacrylate ethyl, and methyl methacrylate to obtain a photochromic resin.

[0025] Among them, coumarin derivatives contain benzopyrone, which is a planar molecule containing a conjugated system. Under the action of ultraviolet light, the changes in the properties of the 7-position electron-donating group and the 3-position and 4-position electron-withdrawing groups in the coumarin molecular structure can cause the coumarin compound to change from yellow, red to blue-green and produce different fluorescent properties, thereby producing glare. However, when added directly as a filler alone, the compatibility and stability are general, and a large amount must be added to meet the glare requirements. Therefore, this application prepares a coumarin derivative containing two alcoholic hydroxyl groups as a reactive monomer to prepare a coumarin polyester, which greatly improves the dispersibility and stability of the chromophore group, reduces the dosage without affecting the glare performance, and uses the unsaturated bond in the polyester to introduce an acrylic monomer copolymer, which helps to interact with the coumarin group and provides a good environment for its reversible photochromism, so that the material can still maintain good photochromic properties during multiple light irradiation and recovery processes.

[0026] Among them, coumarin derivatives can also undergo photoinduced dimerization at an ultraviolet wavelength of 320~350nm, resulting in cross-linking between molecular chain segments, and will depolymerize at an ultraviolet wavelength of 250~260nm, realizing the reversibility of cycloaddition, thereby exerting certain self-repairing properties. However, due to the low content of coumarin introduced in this application, the self-repairing performance is poor; at the same time, under ultraviolet light, the ester bond connected to the fourth position in coumarin will break and produce light release. Based on this, the acrylic acid, acrylamide, 2-methacryloyloxyethyltrimethylammonium chloride, and 2-hydroxymethylacrylate introduced in this application utilize intermolecular hydrogen bonds and ionic interactions to achieve dynamics between chain ends, while not affecting the photoinduced variable properties. At the same time, it imparts excellent self-repairing properties, compensating for the performance degradation caused by polymer breakage.

[0027] Among them, the modified titanium dioxide is prepared by introducing an epoxy group through the hydrolysis of 3-(2,3-epoxypropoxy)propyltrimethoxysilane and reacting it with a hydroxyl group of a coumarin derivative. Because the similar coumarin structure improves the dispersion performance of nano-titanium dioxide in the system, thereby improving the stability of photochromism. At the same time, after modification, due to the direct access to titanium dioxide, the electronic transition and energy level change of the coumarin molecule under light synergistically act with the photocatalytic activity of titanium dioxide, making the system more sensitive to light and the color change more significant, thereby improving the photochromic performance; and promoting the progress of photoinduced dimerization and improving the self-healing property. DETAILED DESCRIPTION

[0028] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0029] It should be noted that the following parts are calculated by weight, and the purchase manufacturers of all raw materials involved in the present invention are not subject to any special restrictions, and illustratively include: CAS No. 1983-81-9 of 4,7-dihydroxycoumarin; CAS No. 627-18-9 of 3-bromo-1-propanol; CAS No. 17455-13-9 of 18-crown ether-6; CAS No. 25265-71-8 of dipropylene glycol; CAS No. 121-91-5 of isophthalic acid; CAS No. 108-31-6 of maleic anhydride; CAS No. 108-31-6 of methylpropylene glycol; : 2163-42-0; CAS number of adipic acid: 124-04-9; polycarbonate diol, molecular weight 2000; CAS number of acrylic acid: 79-10-7; CAS number of acrylamide: 79-06-1; CAS number of 2-methacryloyloxyethyltrimethylammonium chloride: 5039-78-1; CAS number of 2-hydroxymethylacrylate: 10029-04-6; nano-titanium dioxide, particle size 20-80nm; CAS number of 3-(2,3-epoxypropyloxy)propyltrimethoxysilane: 2530-83-8.

[0030] In the following examples, parts are by mass, and the above-mentioned and other raw materials used but not mentioned are commercially available.

[0031] The auxiliary agent includes a leveling agent and an antioxidant in a mass ratio of 0.5:1; the solvent is toluene; and the base resin is polyurethane.

[0032] Example 1: A method for preparing an anti-ultraviolet self-repairing colorful coating material comprises the following steps:

[0033] Step 1: Preparation of coumarin derivatives: 1 part of 4,7-dihydroxycoumarin, 2 parts of potassium carbonate, 1.5 parts of 3-bromo-1-propanol, and 0.7 parts of 18-crown-6 were sequentially added to 15 parts of anhydrous acetone and stirred evenly. The mixture was refluxed at 56°C under microwave conditions for 40 minutes. The solvent was removed under reduced pressure, purified, and dried to obtain a coumarin derivative.

[0034] Step 2: Preparation of coumarin polyester: (1) 10 parts of coumarin derivatives, 7.5 parts of dipropylene glycol, and 14.5 parts of isophthalic acid were mixed evenly, refluxed and stirred at 185°C for 50 minutes, gradually heated to 210°C, continued to stir for 1.5 hours, cooled to 105°C, and added in sequence 2.1 parts of maleic anhydride, 1.65 parts of methyl propanediol, 1 part of adipic acid, and 1 part of polycarbonate diol, first stirred at 125°C for 50 minutes, then heated to 210°C and stirred for 1.5 hours, vacuum treated for 30 minutes, cooled to 140°C, added 0.01 wt% of hydroquinone, and cooled to room temperature to obtain coumarin polyester;

[0035] (2) heating the coumarin polyester to 125°C, adding 1.5 wt% of azobisisobutyronitrile and an acrylic acid monomer in a mass ratio of 1:0.55 to the coumarin polyester, refluxing and stirring at 180°C for 6 hours, cooling to 45°C, neutralizing, and cooling to room temperature to obtain a photochromic resin; wherein the acrylic acid monomer comprises 17 parts of acrylic acid, 12 parts of acrylamide, 4 parts of 2-methacryloyloxyethyltrimethylammonium chloride, 17 parts of 2-hydroxymethylacrylate, and 45 parts of methyl methacrylate;

[0036] Step 3: Preparation of modified nano-titanium dioxide: (1) Add nano-titanium dioxide and 3-(2,3-epoxypropoxy)propyltrimethoxysilane in a mass ratio of 1:0.3 to 70% ethanol solution and disperse them uniformly by ultrasonication. Stir at 45 °C for 3.5 h, filter, wash, and dry to obtain epoxy-modified nano-titanium dioxide.

[0037] (2) Add 2.5 parts of epoxy nano-titanium dioxide to 15 parts of anhydrous acetone and disperse them uniformly by ultrasonication. Then add 2.5 parts of coumarin derivative and 1.5 parts of potassium hydroxide. Stir at 85°C for 3.5 hours, filter, wash and dry to obtain modified nano-titanium dioxide.

[0038] Step 4: Preparation of UV-resistant self-repairing colorful coating material:

[0039] S1: 37 parts of photochromic resin, 32 parts of base resin, 12 parts of modified titanium dioxide, and 1 part of auxiliary agent are sequentially added to 18 parts of solvent and stirred evenly. The stirring time for each time is 25 minutes and the stirring speed is 500 r / min. After the addition is completed, shear stirring is performed for 1.5 hours and vacuum degassing is performed to obtain an anti-UV self-repairing colorful coating;

[0040] S2: The anti-ultraviolet self-repairing colorful coating is applied on the surface of the substrate, dried, and cured at 170° C. for 2.5 h to obtain an anti-ultraviolet self-repairing colorful coating material.

[0041] Example 2: A method for preparing an anti-ultraviolet self-repairing colorful coating material comprises the following steps:

[0042] Step 1: Preparation of coumarin derivatives: 1 part of 4,7-dihydroxycoumarin, 2 parts of potassium carbonate, 1.5 parts of 3-bromo-1-propanol, and 0.7 parts of 18-crown-6 were sequentially added to 15 parts of anhydrous acetone and stirred evenly. The mixture was refluxed at 56°C under microwave conditions for 40 minutes. The solvent was removed under reduced pressure, purified, and dried to obtain a coumarin derivative.

[0043] Step 2: Preparation of coumarin polyester: (1) 10 parts of coumarin derivatives, 7.5 parts of dipropylene glycol, and 14.5 parts of isophthalic acid were mixed evenly, refluxed and stirred at 185°C for 50 minutes, gradually heated to 210°C, continued to stir for 1.5 hours, cooled to 105°C, and added in sequence 2.1 parts of maleic anhydride, 1.65 parts of methyl propanediol, 1 part of adipic acid, and 1 part of polycarbonate diol, first stirred at 125°C for 50 minutes, then heated to 210°C and stirred for 1.5 hours, vacuum treated for 30 minutes, cooled to 140°C, added 0.01 wt% of hydroquinone, and cooled to room temperature to obtain coumarin polyester;

[0044] (2) heating the coumarin polyester to 125°C, adding 1.5 wt% of azobisisobutyronitrile and an acrylic acid monomer in a mass ratio of 1:0.55 to the coumarin polyester, refluxing and stirring at 180°C for 6 hours, cooling to 45°C, neutralizing, and cooling to room temperature to obtain a photochromic resin; wherein the acrylic acid monomer comprises 17 parts of acrylic acid, 12 parts of acrylamide, 4 parts of 2-methacryloyloxyethyltrimethylammonium chloride, 17 parts of 2-hydroxymethylacrylate, and 45 parts of methyl methacrylate;

[0045] Step 3: Preparation of modified nano-titanium dioxide: (1) Add nano-titanium dioxide and 3-(2,3-epoxypropoxy)propyltrimethoxysilane in a mass ratio of 1:0.3 to 70% ethanol solution and disperse them uniformly by ultrasonication. Stir at 45 °C for 3.5 h, filter, wash, and dry to obtain epoxy-modified nano-titanium dioxide.

[0046] (2) Add 2.5 parts of epoxy nano-titanium dioxide to 15 parts of anhydrous acetone and disperse them uniformly by ultrasonication. Then add 2.5 parts of coumarin derivative and 1.5 parts of potassium hydroxide. Stir at 85°C for 3.5 hours, filter, wash and dry to obtain modified nano-titanium dioxide.

[0047] Step 4: Preparation of UV-resistant self-repairing colorful coating material:

[0048] S1: 40 parts of photochromic resin, 30 parts of base resin, 10 parts of modified titanium dioxide, and 2 parts of additives are sequentially added to 18 parts of solvent and stirred evenly. Each stirring time is 25 minutes and the stirring speed is 500 r / min. After the addition is completed, shear stirring is performed for 1.5 hours and vacuum degassing is performed to obtain an anti-UV self-repairing colorful coating;

[0049] S2: The anti-ultraviolet self-repairing colorful coating is applied on the surface of the substrate, dried, and cured at 170° C. for 2.5 h to obtain an anti-ultraviolet self-repairing colorful coating material.

[0050] Example 3: A method for preparing an anti-ultraviolet self-repairing colorful coating material comprises the following steps:

[0051] Step 1: Preparation of coumarin derivatives: 1 part of 4,7-dihydroxycoumarin, 2 parts of potassium carbonate, 1.5 parts of 3-bromo-1-propanol, and 0.7 parts of 18-crown-6 were sequentially added to 15 parts of anhydrous acetone and stirred evenly. The mixture was refluxed at 56°C under microwave conditions for 40 minutes. The solvent was removed under reduced pressure, purified, and dried to obtain a coumarin derivative.

[0052] Step 2: Preparation of coumarin polyester: (1) 10 parts of coumarin derivatives, 7.5 parts of dipropylene glycol, and 14.5 parts of isophthalic acid were mixed evenly, refluxed and stirred at 185°C for 50 minutes, gradually heated to 210°C, continued to stir for 1.5 hours, cooled to 105°C, and added in sequence 2.1 parts of maleic anhydride, 1.65 parts of methyl propanediol, 1 part of adipic acid, and 1 part of polycarbonate diol, first stirred at 125°C for 50 minutes, then heated to 210°C and stirred for 1.5 hours, vacuum treated for 30 minutes, cooled to 140°C, added 0.01 wt% of hydroquinone, and cooled to room temperature to obtain coumarin polyester;

[0053] (2) heating the coumarin polyester to 125°C, adding 1.5 wt% of azobisisobutyronitrile and an acrylic acid monomer in a mass ratio of 1:0.55 to the coumarin polyester, refluxing and stirring at 180°C for 6 hours, cooling to 45°C, neutralizing, and cooling to room temperature to obtain a photochromic resin; wherein the acrylic acid monomer comprises 17 parts of acrylic acid, 12 parts of acrylamide, 4 parts of 2-methacryloyloxyethyltrimethylammonium chloride, 17 parts of 2-hydroxymethylacrylate, and 45 parts of methyl methacrylate;

[0054] Step 3: Preparation of modified nano-titanium dioxide: (1) Add nano-titanium dioxide and 3-(2,3-epoxypropoxy)propyltrimethoxysilane in a mass ratio of 1:0.3 to 70% ethanol solution and disperse them uniformly by ultrasonication. Stir at 45 °C for 3.5 h, filter, wash, and dry to obtain epoxy-modified nano-titanium dioxide.

[0055] (2) Add 2.5 parts of epoxy nano-titanium dioxide to 15 parts of anhydrous acetone and disperse them uniformly by ultrasonication. Then add 2.5 parts of coumarin derivative and 1.5 parts of potassium hydroxide. Stir at 85°C for 3.5 hours, filter, wash and dry to obtain modified nano-titanium dioxide.

[0056] Step 4: Preparation of UV-resistant self-repairing colorful coating material:

[0057] S1: 35 parts of photochromic resin, 35 parts of base resin, 10 parts of modified titanium dioxide, and 2 parts of additives are sequentially added to 18 parts of solvent and stirred evenly. Each stirring time is 25 minutes and the stirring speed is 500 r / min. After the addition is completed, shear stirring is performed for 1.5 hours and vacuum degassing is performed to obtain an anti-UV self-repairing colorful coating;

[0058] S2: The anti-ultraviolet self-repairing colorful coating is applied on the surface of the substrate, dried, and cured at 170° C. for 2.5 h to obtain an anti-ultraviolet self-repairing colorful coating material.

[0059] Comparative Example 1: Based on Example 1, the coumarin derivative was directly added, and the rest of the process remained unchanged, as follows:

[0060] Step 1: Preparation of coumarin derivatives: 1 part of 4,7-dihydroxycoumarin, 2 parts of potassium carbonate, 1.5 parts of 3-bromo-1-propanol, and 0.7 parts of 18-crown-6 were sequentially added to 15 parts of anhydrous acetone and stirred evenly. The mixture was refluxed at 56°C under microwave conditions for 40 minutes. The solvent was removed under reduced pressure, purified, and dried to obtain a coumarin derivative.

[0061] Step 2: Preparation of modified nano-titanium dioxide: (1) Nano-titanium dioxide and 3-(2,3-epoxypropoxy)propyltrimethoxysilane were added to a 70% ethanol solution at a mass ratio of 1:0.3 and ultrasonically dispersed uniformly. The mixture was stirred at 45°C for 3.5 h, filtered, washed, and dried to obtain epoxy-modified nano-titanium dioxide.

[0062] (2) Add 2.5 parts of epoxy nano-titanium dioxide to 15 parts of anhydrous acetone and disperse them uniformly by ultrasonication. Then add 2.5 parts of coumarin derivative and 1.5 parts of potassium hydroxide. Stir at 85°C for 3.5 hours, filter, wash and dry to obtain modified nano-titanium dioxide.

[0063] Step 3: Preparation of UV-resistant self-repairing colorful coating material:

[0064] S1: 37 parts of coumarin derivative, 32 parts of base resin, 12 parts of modified titanium dioxide, and 1 part of auxiliary agent are sequentially added to 18 parts of solvent and stirred evenly. The stirring time for each time is 25 minutes and the stirring speed is 500 r / min. After the addition is completed, shear stirring is performed for 1.5 hours and vacuum degassing is performed to obtain an anti-UV self-repairing colorful coating;

[0065] S2: The anti-ultraviolet self-repairing colorful coating is applied on the surface of the substrate, dried, and cured at 170° C. for 2.5 h to obtain an anti-ultraviolet self-repairing colorful coating material.

[0066] Comparative Example 2: Based on Example 1, acrylic acid monomer was not introduced for copolymerization, and the remaining processes remained unchanged, as follows:

[0067] Step 1: Preparation of coumarin derivatives: 1 part of 4,7-dihydroxycoumarin, 2 parts of potassium carbonate, 1.5 parts of 3-bromo-1-propanol, and 0.7 parts of 18-crown-6 were sequentially added to 15 parts of anhydrous acetone and stirred evenly. The mixture was refluxed at 56°C under microwave conditions for 40 minutes. The solvent was removed under reduced pressure, purified, and dried to obtain a coumarin derivative.

[0068] Step 2: Preparation of coumarin polyester: 10 parts of coumarin derivatives, 7.5 parts of dipropylene glycol, and 14.5 parts of isophthalic acid were mixed uniformly, refluxed and stirred at 185°C for 50 minutes, gradually heated to 210°C, continued to stir for 1.5 hours, cooled to 105°C, and 2.1 parts of maleic anhydride, 1.65 parts of methyl propanediol, 1 part of adipic acid, and 1 part of polycarbonate diol were added in sequence, first stirred at 125°C for 50 minutes, then heated to 210°C and stirred for 1.5 hours, vacuum treated for 30 minutes, cooled to 140°C, added with 0.01wt% of hydroquinone, and cooled to room temperature to obtain coumarin polyester;

[0069] Step 3: Preparation of modified nano-titanium dioxide: (1) Add nano-titanium dioxide and 3-(2,3-epoxypropoxy)propyltrimethoxysilane in a mass ratio of 1:0.3 to 70% ethanol solution and disperse them uniformly by ultrasonication. Stir at 45 °C for 3.5 h, filter, wash, and dry to obtain epoxy-modified nano-titanium dioxide.

[0070] (2) Add 2.5 parts of epoxy nano-titanium dioxide to 15 parts of anhydrous acetone and disperse them uniformly by ultrasonication. Then add 2.5 parts of coumarin derivative and 1.5 parts of potassium hydroxide. Stir at 85°C for 3.5 hours, filter, wash and dry to obtain modified nano-titanium dioxide.

[0071] Step 4: Preparation of UV-resistant self-repairing colorful coating material:

[0072] S1: 37 parts of coumarin polyester, 32 parts of base resin, 12 parts of modified titanium dioxide, and 1 part of auxiliary agent are added to 18 parts of solvent in sequence and stirred evenly. The stirring time for each time is 25 minutes and the stirring speed is 500 r / min. After the addition is completed, shear stirring is performed for 1.5 hours and vacuum degassing is performed to obtain an anti-UV self-repairing colorful coating;

[0073] S2: The anti-ultraviolet self-repairing colorful coating is applied on the surface of the substrate, dried, and cured at 170° C. for 2.5 h to obtain an anti-ultraviolet self-repairing colorful coating material.

[0074] Comparative Example 3: Based on Example 1, only acrylic acid and methyl methacrylate were introduced into the acrylic acid monomer, and the rest of the process remained unchanged, as follows:

[0075] Step 1: Preparation of coumarin derivatives: 1 part of 4,7-dihydroxycoumarin, 2 parts of potassium carbonate, 1.5 parts of 3-bromo-1-propanol, and 0.7 parts of 18-crown-6 were sequentially added to 15 parts of anhydrous acetone and stirred evenly. The mixture was refluxed at 56°C under microwave conditions for 40 minutes. The solvent was removed under reduced pressure, purified, and dried to obtain a coumarin derivative.

[0076] Step 2: Preparation of coumarin polyester: (1) 10 parts of coumarin derivatives, 7.5 parts of dipropylene glycol, and 14.5 parts of isophthalic acid were mixed evenly, refluxed and stirred at 185°C for 50 minutes, gradually heated to 210°C, continued to stir for 1.5 hours, cooled to 105°C, and added in sequence 2.1 parts of maleic anhydride, 1.65 parts of methyl propanediol, 1 part of adipic acid, and 1 part of polycarbonate diol, first stirred at 125°C for 50 minutes, then heated to 210°C and stirred for 1.5 hours, vacuum treated for 30 minutes, cooled to 140°C, added 0.01 wt% of hydroquinone, and cooled to room temperature to obtain coumarin polyester;

[0077] (2) heating the coumarin polyester to 125°C, adding 1.5 wt% of azobisisobutyronitrile and an acrylic acid monomer in a mass ratio of 1:0.55 to the coumarin polyester, refluxing and stirring at 180°C for 6 hours, cooling to 45°C, neutralizing, and cooling to room temperature to obtain a photochromic resin; wherein the acrylic acid monomer comprises 33 parts of acrylic acid and 62 parts of methyl methacrylate;

[0078] Step 3: Preparation of modified nano-titanium dioxide: (1) Add nano-titanium dioxide and 3-(2,3-epoxypropoxy)propyltrimethoxysilane in a mass ratio of 1:0.3 to 70% ethanol solution and disperse them uniformly by ultrasonication. Stir at 45 °C for 3.5 h, filter, wash, and dry to obtain epoxy-modified nano-titanium dioxide.

[0079] (2) Add 2.5 parts of epoxy nano-titanium dioxide to 15 parts of anhydrous acetone and disperse them uniformly by ultrasonication. Then add 2.5 parts of coumarin derivative and 1.5 parts of potassium hydroxide. Stir at 85°C for 3.5 hours, filter, wash and dry to obtain modified nano-titanium dioxide.

[0080] Step 4: Preparation of UV-resistant self-repairing colorful coating material:

[0081] S1: 37 parts of photochromic resin, 32 parts of base resin, 12 parts of modified titanium dioxide, and 1 part of auxiliary agent are sequentially added to 18 parts of solvent and stirred evenly. The stirring time for each time is 25 minutes and the stirring speed is 500 r / min. After the addition is completed, shear stirring is performed for 1.5 hours and vacuum degassing is performed to obtain an anti-UV self-repairing colorful coating;

[0082] S2: The anti-ultraviolet self-repairing colorful coating is applied on the surface of the substrate, dried, and cured at 170° C. for 2.5 h to obtain an anti-ultraviolet self-repairing colorful coating material.

[0083] Comparative Example 4: Based on Example 1, titanium dioxide was not modified and the remaining processes remained unchanged, as follows:

[0084] Step 1: Preparation of coumarin derivatives: 1 part of 4,7-dihydroxycoumarin, 2 parts of potassium carbonate, 1.5 parts of 3-bromo-1-propanol, and 0.7 parts of 18-crown-6 were sequentially added to 15 parts of anhydrous acetone and stirred evenly. The mixture was refluxed at 56°C under microwave conditions for 40 minutes. The solvent was removed under reduced pressure, purified, and dried to obtain a coumarin derivative.

[0085] Step 2: Preparation of coumarin polyester: (1) 10 parts of coumarin derivatives, 7.5 parts of dipropylene glycol, and 14.5 parts of isophthalic acid were mixed evenly, refluxed and stirred at 185°C for 50 minutes, gradually heated to 210°C, continued to stir for 1.5 hours, cooled to 105°C, and added in sequence 2.1 parts of maleic anhydride, 1.65 parts of methyl propanediol, 1 part of adipic acid, and 1 part of polycarbonate diol, first stirred at 125°C for 50 minutes, then heated to 210°C and stirred for 1.5 hours, vacuum treated for 30 minutes, cooled to 140°C, added 0.01 wt% of hydroquinone, and cooled to room temperature to obtain coumarin polyester;

[0086] (2) heating the coumarin polyester to 125°C, adding 1.5 wt% of azobisisobutyronitrile and an acrylic acid monomer in a mass ratio of 1:0.55 to the coumarin polyester, refluxing and stirring at 180°C for 6 hours, cooling to 45°C, neutralizing, and cooling to room temperature to obtain a photochromic resin; wherein the acrylic acid monomer comprises 17 parts of acrylic acid, 12 parts of acrylamide, 4 parts of 2-methacryloyloxyethyltrimethylammonium chloride, 17 parts of 2-hydroxymethylacrylate, and 45 parts of methyl methacrylate;

[0087] Step 3: Preparation of UV-resistant self-repairing colorful coating material:

[0088] S1: 37 parts of photochromic resin, 32 parts of base resin, 12 parts of nano-titanium dioxide, and 1 part of auxiliary agent are added to 18 parts of solvent in sequence and stirred evenly. The stirring time for each time is 25 minutes and the stirring speed is 500 r / min. After the addition is completed, shear stirring is performed for 1.5 hours and vacuum degassing is performed to obtain an anti-UV self-repairing colorful coating;

[0089] S2: The anti-ultraviolet self-repairing colorful coating is applied on the surface of the substrate, dried, and cured at 170° C. for 2.5 h to obtain an anti-ultraviolet self-repairing colorful coating material.

[0090] Performance test: (1) Photochromic performance test: After measuring the initial absorbance of the samples prepared in Examples 1 to 3 and Comparative Examples 1 to 4, the samples were irradiated at an ultraviolet wavelength of 350 nm for 1 h, and the absorbance was measured. Then, the samples were irradiated at an ultraviolet wavelength of 250 nm for 1 h, and the absorbance was measured again. The above operation was repeated for a third time. The experimental data are shown in Table 1.

[0091] (2) Self-repairing performance test: The samples prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were repeatedly polished with 2000-mesh sandpaper for 3 minutes, and the transmittance was measured at 550 nm visible light. After that, the samples were irradiated at an ultraviolet wavelength of 350 nm for 1 hour, and then placed in an environment of 25°C and 100% relative humidity for 10 hours for repair. The transmittance was measured again. The experimental data are shown in Table 1.

[0092] Table 1

[0093]

[0094] Table 2

[0095]

[0096] Conclusion: It can be seen from Table 1 and Table 2 that in Comparative Example 1, coumarin derivatives are directly added, and after treatment at a wavelength of 250nm, the reversible recovery is poor. After three times, due to the poor stability of the directly added coumarin derivatives, decomposition occurs, the absorbance decreases significantly, and the reversible recovery decreases significantly. At the same time, due to the large amount added and uneven dispersion, the transmittance decreases after repair; in Comparative Example 2, no acrylic acid monomer is introduced for copolymerization, and a good environment cannot be provided for the interaction of the coumarin groups. After multiple changes, the reversible recovery decreases, and the repair ability of a single coumarin group is limited, and the self-repairability decreases; in Comparative Example 3, only acrylic acid and methyl methacrylate are introduced into the acrylic monomer, and the self-repairing group is missing, so the stability decreases, and the reversible recovery improvement effect is limited; in Comparative Example 4, titanium dioxide is not modified, the dispersibility is poor, the stability improvement for photochromism is limited, the photochromic ability decreases, and the transmittance decreases, and the self-repairing performance decreases.

[0097] In summary: This application prepares coumarin polyester based on coumarin derivatives and further introduces acrylic acid modification to obtain a self-repairing photochromic resin, and adds modified nano-titanium dioxide to provide basic UV resistance, thereby improving the photochromic and self-repairing properties of the coating material.

[0098] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A UV-resistant self-repairing colorful coating material, characterized by: The invention comprises the following raw materials, based on 100 parts by mass: 35-40 parts of photochromic resin, 30-35 parts of base resin, 10-15 parts of modified titanium dioxide, 1-2 parts of auxiliary agent, and the rest being solvent; The preparation method of the modified titanium dioxide comprises the following steps: (1) adding nano titanium dioxide and 3-(2,3-epoxypropoxy)propyltrimethoxysilane to a 60-70% ethanol solution and uniformly dispersing them by ultrasonication, stirring at 40-50° C. for 3-4 hours, filtering, washing, and drying to obtain epoxy-modified nano titanium dioxide; (2) Add epoxy nano-titanium dioxide to anhydrous acetone and disperse it evenly with ultrasonic waves, add coumarin derivatives and potassium hydroxide, stir at 80-90°C for 3-4 hours, filter, wash, and dry to obtain modified nano-titanium dioxide; The preparation method of the photochromic resin comprises the following steps: (1) uniformly mixing a coumarin derivative, dipropylene glycol and isophthalic acid, adding 1-2 wt% p-toluenesulfonic acid, stirring under reflux at 180-185°C for 40-60 min, gradually heating to 205-210°C, continuing stirring for 1-2 h, cooling to 100-105°C, sequentially adding maleic anhydride, methyl propylene glycol, adipic acid and polycarbonate diol, stirring at 120-125°C for 40-60 min, continuing heating to 205-210°C and stirring for 1-2 h, vacuuming for 30 min, reducing the temperature to 130-150°C, adding 0.01-0.02 wt% hydroquinone, and cooling to room temperature to obtain a coumarin polyester; (2) The coumarin polyester was heated to 120-130°C, 1-1.5 wt% of azobisisobutyronitrile and acrylic acid monomer were added, and the mixture was refluxed and stirred at 170-185°C for 5-7 h, cooled to 40-50°C, neutralized, and cooled to room temperature to obtain a photochromic resin.

2. The UV-resistant self-repairing colorful coating material according to claim 1, characterized in that: The coumarin polyester comprises the following raw materials in parts by weight: 9-11 parts of coumarin derivatives, 7-8 parts of dipropylene glycol, 14-15 parts of isophthalic acid, 2-2.2 parts of maleic anhydride, 1.6-1.7 parts of methylpropylene glycol, 0.8-1.2 parts of adipic acid, and 0.8-1.2 parts of polycarbonate diol.

3. The UV-resistant self-repairing colorful coating material according to claim 1, characterized in that: The preparation method of the coumarin derivative comprises the following steps: adding 4,7-dihydroxycoumarin, potassium carbonate, 3-bromo-1-propanol, and 18-crown ether-6 to anhydrous acetone in sequence and stirring evenly; refluxing and stirring at 55-60° C. under microwave conditions for 40 minutes; removing the solvent under reduced pressure; purifying; and drying to obtain the coumarin derivative.

4. The UV-resistant self-repairing colorful coating material according to claim 3, characterized in that: The coumarin derivative includes the following raw materials, calculated by mass: 0.9-1.1 parts of 4,7-dihydroxycoumarin, 2-2.5 parts of potassium carbonate, 1.4-1.6 parts of 3-bromo-1-propanol, 0.65-0.75 parts of 18-crown ether-6, and 15-20 parts of anhydrous acetone.

5. The UV-resistant self-repairing colorful coating material according to claim 1, characterized in that: The mass ratio of the coumarin polyester to the acrylic acid monomer is 1:0.5-0.6; The acrylic monomer comprises the following raw materials, calculated by mass: 15-20 parts of acrylic acid, 10-15 parts of acrylamide, 3-5 parts of 2-methacryloyloxyethyltrimethylammonium chloride, 15-20 parts of ethyl 2-hydroxymethylacrylate, and 40-50 parts of methyl methacrylate.

6. The UV-resistant self-repairing colorful coating material according to claim 1, characterized in that: The mass ratio of the nano-titanium dioxide to 3-(2,3-epoxypropyloxy)propyltrimethoxysilane is 1:0.3-0.4; The modified nano titanium dioxide comprises the following raw materials, calculated by mass: 2 to 3 parts of epoxy nano titanium dioxide, 2 to 2.5 parts of coumarin derivatives, and 1 to 1.5 parts of potassium hydroxide.

7. The UV-resistant self-repairing colorful coating material according to claim 1, characterized in that: The auxiliary agent includes a leveling agent and an antioxidant in a mass ratio of 0.4 to 0.5:1; the solvent is toluene; and the base resin includes one or both of polyurethane and epoxy resin.

8. The preparation process of a UV-resistant self-repairing colorful coating material according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1: Add photochromic resin, base resin, anti-ultraviolet agent, and additives to the solvent in sequence and stir evenly. Each stirring time is 20-30 minutes and the stirring speed is 400-500 r / min. After the addition is completed, shear stirring is performed for 1-2 hours, and vacuum degassing is performed to obtain an anti-ultraviolet self-repairing colorful coating; S2: coating the anti-ultraviolet self-repairing colorful coating on the surface of the substrate, drying, and curing at 130-170° C. for 2-3 hours to obtain an anti-ultraviolet self-repairing colorful coating material; The coating thickness is 50~80μm.

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