High-transparency self-repairing nano gloss oil and preparation method thereof

Abstract

The invention relates to the technical field of coating compositions, in particular to high-transparency self-repairing nano gloss oil and a preparation method thereof.The high-transparency self-repairing nano gloss oil is prepared through mutual cooperation of self-repairing microcapsules and intrinsic self-repairing, and the self-repairing microcapsules are filled with repairing liquid containing carbon quantum dots; triple self-repairing of microcapsule repairing, photo-thermal response repairing and intrinsic repairing is achieved, the repairing speed is high, and transparency is high.

Description

Technical Field

[0001] This application relates to the field of coating composition technology, specifically to a high-transparency self-healing nano-varnish and its preparation method. Background Technology

[0002] Self-healing coatings can automatically restore their integrity and appearance after being subjected to mechanical damage. Existing self-healing coatings are mainly divided into two categories: microencapsulated and intrinsic types.

[0003] Microcapsule-type self-healing coatings achieve repair by embedding microcapsules containing repair agents in the coating. When the coating is scratched, the microcapsules rupture and release the repair agent to fill the damaged area (CN118085711A). This type of coating repairs quickly, but it has two main drawbacks: first, the difference in refractive index between the microcapsules and the base resin can easily lead to a decrease in the coating's transparency; second, once the repair agent is exhausted, it cannot continue to repair, making it a one-time repair.

[0004] Intrinsic self-healing coatings rely on reversible chemical bonds (such as disulfide bonds, Diels-Alder bonds, etc.) in the polymer molecular chain to achieve repair (CN104312405B), but the repair speed is slow and often requires heating or light to trigger.

[0005] Therefore, this paper seeks to provide a high-transparency self-healing nano-varnish that achieves synergistic effects of rapid repair and multiple repairs, and its preparation method. Summary of the Invention

[0006] The purpose of this invention is to provide a high-transparency self-healing nano-varnish and its preparation method. By synergistically combining self-healing microcapsules with intrinsic self-healing, and filling the self-healing capsules with a repair liquid containing carbon quantum dots, triple self-healing—microcapsule repair, photothermal response repair, and intrinsic repair—is achieved. This results in fast repair speed and high transparency, solving the problems of difficulty with single microcapsules and the existence of intrinsic repair in the prior art.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following solution: A high-transparency self-healing nano-varnish comprises the following components by weight: 55-70 parts polyether, 10-12 parts chain extender containing disulfide bonds, 20-25 parts diluent, 3-4 parts photoinitiator, 4-8 parts nano-silica, 6-12 parts self-healing microcapsules, and 0.3-0.8 parts additives; the self-healing microcapsules have a double-shell structure, with the core material being a repair liquid containing carbon quantum dots, the inner shell being polyurea resin, and the outer shell being polymethyl methacrylate.

[0008] The technical concept of this invention is as follows: In the raw material components for preparing nano-varnish: 1) self-healing microcapsules are added, forming the first layer of repair after the nano-varnish forms a coating. When the coating surface is subjected to external force and micron-level scratches occur, the crack propagation causes the microcapsules to rupture; the inner polyurea shell is sensitive to stress, ensuring timely rupture; the outer polymethyl methacrylate ruptures along with the inner shell; the core material tung oil (containing carbon quantum dots) flows out rapidly under capillary action, filling the scratched area; the tung oil comes into contact with oxygen in the air and undergoes an oxidative polymerization reaction, solidifying to form a new film; this process is carried out at room temperature without heating, and the scratch repair can be completed within 2-5 minutes.

[0009] Polyether, chain extender containing disulfide bonds, and self-healing microcapsules serve as the organic resin matrix, constituting the main framework of the coating after the nano-varnish is cured; diluent is used to adjust the viscosity of the system, participate in the cross-linking reaction, and is an active solvent; photoinitiator is a functional additive that initiates the UV curing reaction; leveling agent and defoamer are used as coating additives; nano-silica serves as a functional filler to improve the hardness and wear resistance of subsequent coatings.

[0010] 2) The addition of carbon quantum dot-containing tung oil to the core material of the self-healing microcapsules creates a second layer of repair. Tung oil contains conjugated double bonds, which undergo oxidative polymerization upon contact with air to solidify into a film without the need for additional catalysts. Carbon quantum dots possess excellent photothermal conversion properties, converting light energy into heat energy, triggering the controlled release of the microcapsules and accelerating the curing of the tung oil. For incompletely ruptured self-healing microcapsules or areas requiring secondary repair, under sunlight, the carbon quantum dots in the core material absorb light energy and efficiently convert it into heat energy (photothermal conversion efficiency can reach over 50%). The localized temperature increase softens the polyurea resin in the inner shell of the self-healing microcapsules, promoting shell rupture; releasing more repair agents, while the heat accelerates the oxidative curing reaction of the tung oil.

[0011] 3) Polyether and disulfide-bonded chain extenders are added to the raw material components of the nano-varnish to form a third layer of repair. Utilizing the principle of mercapto-olefin click chemistry, polyether and dithiol chain extenders containing disulfide bonds are used as the main raw materials. Under the action of a photoinitiator, a cross-linked network with dynamic disulfide bonds is constructed, serving as the matrix film-forming material of the varnish. Under UV light irradiation, the photoinitiator decomposes to generate free radicals, initiating a click reaction between mercapto groups and acrylate double bonds, forming a cross-linked network. Reversible breakage and recombination reactions can occur at room temperature. When microcracks appear in the coating, the dynamic exchange of disulfide bonds rearranges the molecular chains, gradually filling the cracks and achieving multiple repairs. This can repair minute scratches (nanoscale microcracks) that have not reached the microcapsules, or residual minor defects after microcapsule repair.

[0012] Furthermore, the core material repair solution of the self-healing microcapsule is a mixture of tung oil and carbon quantum dots, with the carbon quantum dots accounting for 1-5% of the total mass of the repair solution and having a particle size of 2-10 nm.

[0013] Furthermore, the particle size of the self-healing microcapsules is 3~8μm.

[0014] Furthermore, the inner shell thickness is 50~100nm, and the outer shell thickness is 100~200nm.

[0015] Furthermore, the polyether is polyethylene glycol diacrylate, polypropylene glycol diacrylate, or polytetrahydrofuran ether diacrylate, with a molecular weight of 1000-2000.

[0016] Furthermore, the chain extender containing disulfide bonds is a 4,4'-dithiodiphenylamine derivative, which can be repaired at room temperature.

[0017] Furthermore, the nano-silica has a particle size of 20-30 nm and its surface is treated with a silane coupling agent for hydrophobicity.

[0018] Furthermore, the diluent is isobornyl acrylate, 1,6-hexanediol diacrylate, or tripropylene glycol diacrylate; the photoinitiator is a free radical type.

[0019] A method for preparing a high-transparency self-healing nano-varnish includes the following steps: Step 1: Preparation of self-healing microcapsules with a double-shell structure: Carbon quantum dots are added to tung oil to obtain a repair solution in which carbon quantum dots are uniformly suspended; the repair solution is first emulsified to form an emulsion, and then a polyurea inner shell is formed by interfacial polymerization, and then a polymethyl methacrylate outer shell is coated on the surface by emulsion polymerization. Step 2: Mix polyether, chain extender containing disulfide bonds, diluent, and photoinitiator, and then add nano-silica for dispersion; Step 3: Add the double-shell self-healing microcapsules, stir well, and filter to obtain the self-healing nano-varnish.

[0020] Furthermore, in steps two and three, the stirring rates are 12000~16000 rpm and 500~700 rpm, respectively.

[0021] The beneficial effects of this invention are as follows: By incorporating self-healing microcapsules, the invention establishes a first layer of repair after the nano-varnish coating is formed; the addition of tung oil containing carbon quantum dots to the core material of the self-healing microcapsules forms a second layer of repair; and the addition of polyether and disulfide-bonded chain extenders to the raw material components of the nano-varnish forms a third layer of repair. This creates a triple repair mechanism for cracks in the nano-varnish coating. The self-healing microcapsules are responsible for rapidly repairing visible scratches with high transparency; the carbon quantum dots in the core material undergo a photothermal reaction, providing secondary repair capabilities, allowing the self-healing microcapsules to be reused multiple times; and the nano-varnish matrix possesses a dynamic disulfide bond cross-linking network, responsible for long-term maintenance and repairing minute damage that the self-healing microcapsules cannot cover. This triple repair synergistic effect achieves comprehensive repair of scratches from the nanometer to the micrometer scale after the nano-varnish has cured. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the cross-sectional structure of the self-healing microcapsule of the present invention.

[0023] Reference numerals: 1-outer shell, 2-inner shell, 3-core material. Detailed Implementation

[0024] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0025] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0026] Example 1 Example 1 describes a method for preparing a high-transparency self-healing nano-varnish, comprising the following steps: (1) Preparation of self-healing microcapsules with double shell structure To prepare a repair solution containing carbon quantum dots, carbon quantum dot powder (6 nm particle size, 0.2 parts) was added to tung oil (9.8 parts) and ultrasonically dispersed for 30 minutes to obtain a core material repair solution containing 2% carbon quantum dots in uniform suspension.

[0027] The core material repair solution was added to an aqueous phase containing 1% polyvinyl alcohol and emulsified at high speed (12000 rpm / min) to form an O / W emulsion (dispersed phase / continuous phase), with the emulsion droplet size controlled at 3~5 μm; Isocyanate prepolymer and ethylenediamine were added to an O / W emulsion, and the reaction was carried out at 50°C for 2 hours to form a polyurea inner shell with a thickness of 50-100 nm. Methyl methacrylate monomer and potassium persulfate initiator were then added, and polymerization was carried out at 70°C for 4 hours to form a polymethyl methacrylate outer shell with a thickness of 100-200 nm. The mixture was then centrifuged, washed, and dried sequentially to obtain bi-shell microcapsules with a particle size of 3-7 μm. (Refer to...) Figure 1 .

[0028] (2) Preparation of self-healing nano-varnish 55 parts of polyethylene glycol diacrylate (PEGDA, molecular weight 1000), 12 parts of 4,4'-dithiodiphenylamine derivative, 20 parts of isobornyl acrylate (IBOA), 3 parts of photoinitiator 184, 0.3 parts of leveling agent (BYK-333), and 0.2 parts of defoamer (BYK-088) were mixed evenly. 4 parts of nano silica were added and dispersed at high speed (15000 rpm) for 15 minutes. 8 parts of double-shell self-healing microcapsules were then added and stirred at low speed (600 rpm) for 10 minutes. After filtration, the self-healing nano varnish was obtained.

[0029] (3) Performance testing Nano-varnish was spin-coated onto a glass substrate to a film thickness of approximately 30 μm, and performance testing was performed after UV curing. Transmittance: measured using a UV-Vis spectrophotometer (wavelength 550nm).

[0030] Pencil hardness: Tested according to GB / T6739-2006.

[0031] Microcapsule repair test: A scratch with a width of about 20 μm was made with a blade, and the repair was observed and recorded under a microscope after being placed at room temperature for 4 minutes.

[0032] Photothermal response repair test: The coating was placed under simulated sunlight for 10 minutes, the repair status was observed and the data was recorded.

[0033] Intrinsic repair test: Repeatedly scratch and repair the same location 10 times, observe the repair situation and record the data.

[0034] Storage stability: Store in a 40℃ constant temperature chamber for 3 months, observe for the appearance of sediment, and test the repair status.

[0035] Water resistance test: Tested according to GB / T1733.

[0036] Impact strength test: Tested according to GB / T1732.

[0037] Neutral salt spray resistance test: Tested according to GB / T1771.

[0038] The application method for nano varnish before application is as follows: 1) It must be thoroughly stirred before use.

[0039] 2) The diluted paint used in the painting process should be filtered through a 400-mesh cloth before use.

[0040] 3) After opening and using the product, close the lid and seal it immediately.

[0041] 4) The construction environment should be kept clean and dust-free, with the optimal temperature between 20 and 30°C and the appropriate relative humidity. Greater than 80%.

[0042] 5) It is forbidden to mix different types of paint or thinner.

[0043] 6) The product should be stored in a well-ventilated and dry place, away from direct sunlight. Shelf life is from the date of production. Please use within 6 months to avoid affecting the quality.

[0044] Example 2 In Example 2, the content of self-healing microcapsules was adjusted to 10 parts, the content of carbon quantum dots was adjusted to 1% (particle size 2nm), the content of polypropylene glycol diacrylate was 70 parts, the content of disulfide bond chain extender was 10 parts, the content of nano silica was 5 parts, and the rest was the same as in Example 1.

[0045] Example 3 The microcapsule particle size was adjusted to 5~8μm, the carbon quantum dot content was adjusted to 3% (particle size 10nm), and the rest was the same as in Example 1.

[0046] Comparative Example 1 This comparative example uses a double-shell self-healing microcapsule without carbon quantum dots (its core material is pure tung oil), and the rest is the same as in Example 1.

[0047] Comparative Example 2 This comparative example uses a single-layer polymethyl methacrylate outer shell (without a polyurea inner shell), and the core material is tung oil containing 2% carbon quantum dots. The rest is the same as in Example 1.

[0048] Comparative Example 3 This comparative example uses a chain extender without disulfide bonds, and instead uses an equal amount of ethylene glycol dimercaptoacetate (which has no disulfide bonds), otherwise it is the same as in Example 1.

[0049] Table 1. Comparison of the performance of nano-varnishes in Examples 1-3 and Comparative Examples 1-3 of the present invention. Referring to Table 1, it can be seen from the above performance data that, compared with Comparative Example 1, the carbon quantum dots mixed with tung oil used as the core material of microcapsules in Examples 1-3 have excellent photothermal conversion performance, which can convert light energy into heat energy, trigger the controllable release of tung oil in the microcapsules and accelerate the curing of tung oil.

[0050] Compared with Comparative Example 2, the present invention has a self-healing microcapsule with a double-shell structure. The outer shell of polymethyl methacrylate ensures the initial high transparency and rigidity, while the inner shell of polyurea provides toughness and a chemical barrier. Both ensure that the microcapsule can exist stably in the nano varnish for a long time and that it can reliably rupture and release the repair agent when repair is needed, such as when scratches are generated or photothermal triggering occurs.

[0051] Compared to Comparative Example 3, this invention enables the matrix of the nano-varnish to possess a dynamic disulfide bond cross-linking network, responsible for long-term maintenance and enabling multiple repairs. It can repair minute scratches (nanoscale microcracks) that have not reached the microcapsules, or minor defects remaining after microcapsule repair.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A high-transparency self-healing nano-varnish, characterized in that, The following components are included in parts by weight: The composition includes 55-70 parts polyether, 10-12 parts chain extender containing disulfide bonds, 20-25 parts diluent, 3-4 parts photoinitiator, 4-8 parts nano silica, 6-12 parts self-healing microcapsules, and 0.3-0.8 parts additives. The self-healing microcapsules have a double-shell structure, with the core material being a repair liquid containing carbon quantum dots, the inner shell being polyurea resin, and the outer shell being polymethyl methacrylate.

2. The high-transparency self-healing nano-varnish according to claim 1, characterized in that, The core material repair solution of the self-healing microcapsule is a mixture of tung oil and carbon quantum dots, with the carbon quantum dots accounting for 1-5% of the total mass of the repair solution and having a particle size of 2-10 nm.

3. The high-transparency self-healing nano-varnish according to claim 1, characterized in that, The self-healing microcapsules have a particle size of 3~8μm.

4. The high-transparency self-healing nano-varnish according to claim 1, characterized in that, The inner shell has a thickness of 50~100nm, and the outer shell has a thickness of 100~200nm.

5. The high-transparency self-healing nano-varnish according to claim 1, characterized in that, The polyether is polyethylene glycol diacrylate, polypropylene glycol diacrylate, or polytetrahydrofuran ether diacrylate, with a molecular weight of 1000~2000.

6. The high-transparency self-healing nano-varnish according to claim 1, characterized in that, The chain extender containing disulfide bonds is a 4,4'-dithiodiphenylamine derivative.

7. The high-transparency self-healing nano-varnish according to claim 1, characterized in that, The nano-silica has a particle size of 20-30 nm and its surface is treated with a silane coupling agent for hydrophobicity.

8. The high-transparency self-healing nano-varnish according to claim 1, characterized in that, The diluent is isobornyl acrylate, 1,6-hexanediol diacrylate, or tripropylene glycol diacrylate; the photoinitiator is a free radical type.

9. A method for preparing a high-transparency self-healing nano-varnish, characterized in that, Includes the following steps: Step 1, Preparation of self-healing microcapsules with double shell structure: Carbon quantum dots are added to tung oil to obtain a repair solution. The repair solution is first emulsified to form an emulsion. A polyurea inner shell is formed by interfacial polymerization. Then, a polymethyl methacrylate outer shell is coated on the surface by emulsion polymerization. Step 2: Mix polyether, chain extender containing disulfide bonds, diluent, and photoinitiator, and then add nano-silica for dispersion; Step 3: Add the double-shell self-healing microcapsules, stir well, and filter to obtain the self-healing nano-varnish.

10. The method for preparing a high-transparency self-healing nano-varnish according to claim 9, characterized in that, In steps two and three, the stirring speeds are 12000~16000rpm and 500~700rpm, respectively.

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