High-weather-resistance normal-pressure polymerized acrylic resin and coating preparation process thereof

Abstract

The invention discloses high-weather-resistance normal-pressure polymerized acrylic resin and a coating preparation process thereof, and belongs to the technical field of polymer synthesis and coatings. The resin is prepared from the following monomers in parts by weight through free radical polymerization: 30-50 parts of a hard monomer, 15-35 parts of a soft monomer, 2-8 parts of a functional monomer I containing an active crosslinking functional group, 5-15 parts of a functional monomer II containing a weather-proof structural unit and 1-5 parts of an unsaturated carboxylic acid monomer. The preparation method comprises the following steps: dropwise adding 60-80% of a mixed monomer liquid under a reflux condition for polymerization, dropwise adding the residual monomers and an initiator, and carrying out a heating reaction at normal pressure in the whole process. The invention also provides a high-weather-resistance coating containing the resin. Through cooperation of specific monomer combination and a step-by-step process, the resin is endowed with excellent intrinsic weather resistance and balanced mechanical properties under a normal pressure condition, and the prepared coating has remarkable light and color retention performance after long-term outdoor aging and is suitable for the field of high-end outdoor protection and decoration.

Description

Technical Field

[0001] This invention relates to the fields of polymer synthesis and coating technology, specifically to an acrylic resin with excellent weather resistance, its preparation method, and its applications. More specifically, this invention provides an acrylic resin that can be polymerized under normal pressure, whose intrinsic high weather resistance is endowed by molecular structure design, and a high-performance coating containing this resin. Background Technology

[0002] Acrylic resins are widely used in automotive, outdoor construction, and industrial protection fields due to their excellent gloss and color retention, chemical resistance, and decorative properties. Outdoor applications are subject to harsh environments, requiring coatings to withstand long-term ultraviolet radiation, humidity, heat, and high and low temperature cycles without yellowing, chalking, loss of gloss, or cracking; that is, they must have high weather resistance.

[0003] Currently, the mainstream methods to improve the weather resistance of acrylic resins include: (1) introducing monomers containing ultraviolet absorbing groups (such as benzotriazoles) through copolymerization; (2) physically adding small molecule additives such as light stabilizers and antioxidants; and (3) introducing weather-resistant elements such as fluorine and silicon through molecular design. However, methods (1) and (2) have problems such as easy migration, exudation, and volatilization of small molecule additives, resulting in insufficient long-term protection; although method (3) can significantly improve the intrinsic weather resistance of the resin, the price of fluorine-containing and silicon monomers is expensive, and polymerization often requires high pressure conditions (such as CN106380537B), which has high requirements for equipment and increases costs and safety risks.

[0004] Meanwhile, industrial production prioritizes efficiency, safety, and environmental protection. Atmospheric pressure polymerization processes (such as solution polymerization) are simple to operate, safe, and easy to control, making them an ideal industrialization path. However, how to prepare acrylic resins with both excellent initial mechanical properties and long-lasting weather resistance under atmospheric pressure through clever design of monomer combinations and polymerization processes remains a pressing technical challenge in this field. Some existing improvements, such as the high-solids, low-viscosity resin involved in patent CN118834333A, while optimizing the process, still have room for improvement in terms of weather resistance durability and overall performance balance. While patent CN121159761A mentions weather-resistant monomers and atmospheric pressure polymerization, it does not provide a specific technical solution for achieving comprehensive performance synergistic with intrinsic high weather resistance under atmospheric pressure.

[0005] Therefore, developing an acrylic resin and its coating that is cost-effective, process-friendly (at normal pressure), and can achieve excellent long-lasting weather resistance from the resin molecular structure itself has significant industrial value. Summary of the Invention

[0006] 1. Technical problem to be solved: This invention aims to overcome the shortcomings of the prior art and provide a high-weather-resistant, atmospheric-pressure polymerized acrylic resin and its coating preparation process. By carefully selecting monomer combinations with specific structures and optimizing their ratios, this invention employs a unique stepwise dropwise addition process under atmospheric pressure to synthesize an acrylic copolymer with a rudimentary "core-shell" structure and an internal cross-linked network. This resin achieves a balance of excellent weather resistance, mechanical properties, and storage stability from the perspective of its molecular chain structure, without relying on expensive fluorinated / silicone monomers or large amounts of small-molecule additives.

[0007] 2. Technical Solution: To solve the above problems, the present invention adopts the following technical solution.

[0008] This invention provides a high weather-resistant, atmospheric-pressure polymerizable acrylic resin, which is prepared by free radical polymerization of monomer raw materials comprising the following parts by weight: (a) 30-50 parts of hard monomer, selected from at least one of methyl methacrylate, styrene, and acrylonitrile; (b) 15-35 parts of soft monomer, selected from at least one of butyl acrylate, 2-ethylhexyl acrylate, and isooctyl acrylate; (c) Functional monomer I2-8 parts, which is a monomer containing an active cross-linking functional group, selected from at least one of (meth)acrylate, (meth)acrylate, acrylamide, and N-hydroxymethylacrylamide; (d) Functional monomer II 5-15 parts, which is a monomer containing weather-resistant structural units, selected from at least one of (meth)acrylate isobornyl ester and vinyl benzoate; (e) 1-5 parts of unsaturated carboxylic acid monomers, selected from at least one of acrylic acid, methacrylic acid, and itaconic acid; In addition, based on the total weight parts of the monomer raw materials, there are 0.2-2 parts of initiator and 40-60 parts of organic solvent.

[0009] Preferably, the weight ratio of the hard monomer (a) to the soft monomer (b) is (1.5:1) to (2.5:1). The functional monomer II is preferably isobornyl methacrylate or vinyl benzoate.

[0010] This invention provides a method for preparing the above-mentioned high weather-resistant atmospheric pressure polymerized acrylic resin, comprising the following steps: S1. Premixing: Mix all monomers (a)-(e), a portion of the initiator and a portion of the organic solvent evenly to obtain a mixed monomer solution; S2. First step of dropwise polymerization: Under normal pressure and reflux conditions, the first part of the mixed monomer liquid, which accounts for 60-80% of the total amount of the mixed monomer liquid, is added dropwise at a uniform rate to the reaction system containing the remaining organic solvent over 2-4 hours. After the dropwise addition is completed, the reaction is kept at the temperature for 0.5-1.5 hours. S3. Second step of dropwise polymerization: The second part of the mixed monomer liquid, accounting for 20-40% of the total amount of the mixed monomer liquid, and the remaining initiator are added dropwise to the reaction system over 1-2 hours, and then the temperature is raised to 135-145℃ and kept at the temperature for 2-4 hours. S4. Post-processing: After the reaction is completed, the temperature is lowered and the material is discharged to obtain the high weather-resistant atmospheric pressure polymerized acrylic resin.

[0011] This invention provides a high weather-resistant coating, which comprises the following components in parts by weight: 50-70 parts of the high weather-resistant, atmospheric-pressure polymerized acrylic resin as described above; 15-30 parts of pigments and fillers; 5-15 parts of curing agent; 1-5 parts of auxiliary agent; Solvent 10-20 parts.

[0012] The curing agent can be selected according to the active functional groups contained in the resin. For example, when the resin contains hydroxyl groups, an isocyanate curing agent (such as HDI trimer) can be selected; when it contains epoxy groups, an amino resin or a polyacid curing agent can be selected.

[0013] This invention provides a method for preparing the above-mentioned high weather-resistant coating, wherein the components are mixed in proportion, dispersed uniformly at high speed, and then filtered to obtain the coating.

[0014] 3. Beneficial effects: Compared with the prior art, the technical solution provided by this invention has the following advantages: (1) It provides excellent weather resistance and durability. This invention introduces a specific functional monomer II, which forms a side group structure with steric hindrance and stable chemical bonds in the polymer molecular chain. This structure can effectively attenuate ultraviolet light energy, inhibit the occurrence of photo-oxidation reaction, and improve the overall hydrophobicity and thermal stability of the resin, thereby enhancing the coating's ability to resist aging in harsh environments such as ultraviolet radiation, high temperature and high humidity at the molecular level.

[0015] (2) The optimal balance of the overall mechanical properties of the coating film is achieved. By limiting the specific ratio range of hard monomers and soft monomers and combining it with a stepwise drop-addition polymerization process, the present invention is conducive to forming a microstructure in the copolymer with gradient changes in composition and properties. This structure enables the final coating film to maintain high hardness, good wear resistance and adhesion, while also having excellent flexibility and impact resistance, overcoming the technical contradiction that it is difficult to achieve both high hardness and high toughness.

[0016] (3) A stable and easily industrialized resin synthesis process has been obtained. The preparation method provided by this invention is carried out under normal pressure throughout the process, without the need for special pressurization or complex control equipment. The process has a wide safety window and is easy to operate. The monomer and solvent system used are common, and the polymerization reaction process and exothermic reaction are effectively controlled by stepwise dropwise addition, which is conducive to obtaining resin products with uniform molecular weight distribution and good storage stability, and is suitable for large-scale production.

[0017] (4) It broadens the application range of outdoor long-lasting protective coatings. Based on the above-mentioned excellent properties, the coatings prepared by the resin of this invention are suitable for high-end outdoor buildings, transportation equipment and engineering facilities, etc., and meet the requirements of long-term weather resistance and decoration integration.

[0018] It should be noted that the structures not described in this invention are not related to the design points and improvement directions of this invention, and are the same as or can be implemented using existing technologies, so they will not be elaborated here. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail and completely below with reference to several specific embodiments and comparative experiments. However, the following embodiments should not be construed as limiting the scope of protection of this invention. Unless otherwise specified, the raw materials used in the embodiments are all commercially available conventional reagents. "Ambient pressure" refers to the reaction system pressure being atmospheric pressure, approximately 0.1 MPa.

[0020] Part 1: Examples of Preparation of High Weather-Resistant Acrylic Resin Example 1: Preparation of Resin R1 This example demonstrates a typical preparation process using isobornyl methacrylate (IBOMA) as functional monomer II.

[0021] 1. Preparation of premix: In a dry 500mL dropping bottle, add and mix the following raw materials (by weight, corresponding to the aforementioned parts by weight) sequentially to form a homogeneous mixed monomer premix: Methyl methacrylate (hard monomer a): 35.0 g Butyl acrylate (soft monomer b): 20.0 g Hydroxypropyl acrylate (functional monomer I, containing hydroxyl groups): 5.0 g Isoborneol methacrylate (functional monomer II, weather-resistant unit): 10.0 g Acrylic acid (functional monomer, containing carboxyl group): 3.0 g The first step uses benzoyl peroxide as an initiator: 0.8 g (approximately 66.7% of the total initiator). Dodecyl mercaptan (chain transfer agent): 0.2 g Xylene (organic solvent): 25.0 g 2. Initial Feeding and Heating: Add 25.0 g of xylene to a 1000 mL four-necked flask equipped with a stirrer, thermometer, reflux condenser, and constant pressure dropping funnel. Purge the air in the reactor with nitrogen for 30 minutes. Then, under continuous micro-nitrogen protection, start stirring and heat until the solvent is refluxed and the temperature stabilizes at 130±2℃.

[0022] 3. First Step Droplet Polymerization (Constructing a Core Structure Rich in Hard Monomers): 70% (approximately 70.0 g) of the total amount of the mixed monomer premix prepared in Step 1 is added dropwise to the reaction flask at a uniform and continuous rate over 3.0 hours using a constant-pressure dropping funnel. During the droplet addition, the system is kept under reflux, and the temperature is controlled at 130±2℃. After the droplet addition is complete, the reaction is continued at 130℃ for 1.0 hour to allow the previously added monomers to fully polymerize, forming a polymer core with a high glass transition temperature (Tg) and abundant reaction sites.

[0023] 4. Second step: Droplet polymerization (constructing a gradient "shell" structure): The remaining 30% (approximately 30.0 g) of the mixed monomer premix is ​​thoroughly mixed with an additional 0.4 g of benzoyl peroxide (pre-dissolved in 5.0 g xylene), and then added dropwise to the reaction system at a uniform rate over 1.5 hours. The monomers added in this stage tend to continue reacting on the already formed "core," introducing more flexible segments and functional monomer II. After the addition is complete, the reaction system temperature is raised to 140°C and maintained at this temperature for 3.0 hours to ensure a monomer conversion rate >98%.

[0024] 5. Post-treatment: After the heat preservation period, stop heating and allow the reaction system to cool naturally to below 80℃. Add 0.05 g of hydroquinone (polymerization inhibitor) and stir for 30 minutes to terminate the reaction. Filter the obtained product through a 200-mesh filter to obtain a light yellow, transparent, viscous liquid, designated as high weather-resistant acrylic resin R1.

[0025] Resin performance characterization: The solid content of resin R1 was determined to be 68.2% (GB / T 1725), the viscosity was 2500 mPa·s (25℃, Brookfield rotational viscometer), and the acid value was 8.2 mgKOH / g (GB / T 6743).

[0026] Example 2: Preparation of Resin R2 This embodiment aims to demonstrate the effects of another functional monomer II (vinyl benzoate) and different combinations of hard / soft monomers.

[0027] 1. Preparation of premixed solution: Mix the following materials in a dropping bottle: Styrene (hard monomer a): 25.0 g Methyl methacrylate (hard monomer a): 10.0 g 2-Ethylhexyl acrylate (soft monomer b): 25.0 g Hydroxyethyl acrylate (functional monomer I): 4.0 g Vinyl benzoate (functional monomer II, weather-resistant unit): 12.0 g Methacrylic acid (functional monomer, containing carboxyl group): 2.0 g Di-tert-butyl peroxide (initiator): 1.0 g Butyl acetate (organic solvent): 50.0 g 2. Polymerization process: Add 50.0 g of butyl acetate to the reactor and heat to reflux (approximately 125°C) under nitrogen protection. First, add 75% of the total premix solution dropwise over 2.5 hours at a uniform rate, and maintain the temperature at 125°C for 1.0 hour. Then, add the remaining 25% of the premix solution and a mixture of 0.3 g of di-tert-butyl peroxide (dissolved in 5 g of butyl acetate) dropwise over 1.0 hour, and then raise the temperature to 140°C and maintain the reaction temperature for 2.5 hours.

[0028] 3. Post-processing: Cool to 85℃, add 0.05g of polymerization inhibitor, filter and discharge to obtain resin R2.

[0029] Performance characteristics: solid content 65.1%, viscosity 1800 mPa·s (25℃), acid value 5.0 mgKOH / g.

[0030] Example 3: Preparation of Resin R3 (demonstrating the adjustment of hard / soft monomer ratio) 1. Preparation of premixed solution: Methyl methacrylate: 40.0 g, Styrene: 10.0 g (total of 50 parts hard monomers) Butyl acrylate (soft monomer): 20.0 g Hydroxypropyl acrylate (functional monomer I): 6.0 g Isoborneol methacrylate (functional monomer II): 8.0 g Acrylic acid: 2.0 g Benzoyl peroxide: 1.0 g, Dodecyl mercaptan: 0.1 g Propylene glycol methyl ether acetate (PMA): 30.0 g 2. Polymerization process: Initial solvent PMA 30g, heated to 135℃ and refluxed. First step: 80% premixed solution was added dropwise (3 hours), and the temperature was maintained at 135℃ for 1 hour. Second step: the remaining 20% ​​premixed solution and 0.3g BPO solution were added dropwise (1 hour), and the temperature was raised to 145℃ and maintained for 3 hours.

[0031] 3. Post-treatment: Conventional post-treatment yields resin R3.

[0032] Performance characteristics: solid content 70.5%, viscosity 3500 mPa·s, acid value 6.1 mgKOH / g.

[0033] Comparative Example 1: Preparation of Resin D1 (without functional monomer II) The formulation and preparation process are the same as in Example 1, the only difference being that 10.0 g of isobornyl methacrylate is completely replaced with an equal weight of methyl methacrylate. The resulting resin is denoted as D1.

[0034] Comparative Example 2: Preparation of Resin D2 (replacing functional monomer type II) The formulation and preparation process are the same as in Example 1, except that 10.0 g of isobornyl methacrylate is replaced with 10.0 g of cyclohexyl methacrylate. The resulting resin is designated as D2.

[0035] Comparative Example 3: Preparation of Resin D3 (by changing the polymerization process) The formulation was exactly the same as in Example 1. However, the polymerization process was changed to a single-feed operation: all raw materials (monomer, initiator, chain transfer agent, and all solvents) were added to the reactor at once, the temperature was raised to 130°C and maintained for 5.0 hours. Post-treatment was the same as in Example 1. The resulting resin was designated D3.

[0036] Comparative Example 4: Preparation of Resin D4 (simulating a standard formulation) The formulation referenced common hydroxyl acrylic resin: methyl methacrylate 45.0g, butyl acrylate 30.0g, hydroxypropyl acrylate 5.0g, acrylic acid 3.0g, without any functional monomer II added. The initiator, chain transfer agent, and solvent types and amounts were the same as in Example 1. Polymerization was performed using a one-time feeding process (same as Comparative Example 3). The resulting resin was designated D4.

[0037] Part Two: Comparative Testing of Resin Performance The key performance tests were performed on the six resins (R1, R2, R3, D1, D2, D3, D4) prepared above, and the results are summarized in Table 1.

[0038] Table 1: Comparison of basic properties and thermal stability of resins

[0039] Conclusions at the resin level: 1. The resins (R1-R3) of this invention have significantly higher thermal decomposition initiation temperatures (T0). d5% The results of the ) and char residue indicate that the molecular chain has better thermal stability and heat oxidation resistance, which is directly attributed to the rigid and stable structural unit introduced by functional monomer II.

[0040] 2. The thermal stability data of Comparative Example D2 (cyclohexyl ester instead of isobornyl ester) are between those of the present invention and ordinary resins, proving that the contribution of specific bulk monomers such as isobornyl ester and vinyl benzoate is more prominent.

[0041] 3. The viscosity of Comparative Example D3 (one-time feeding) is abnormally high, and it tends to gel after accelerated storage, indicating that its polymerization process is difficult to control, the molecular weight distribution is wide, or there is micro-crosslinking. The stepwise dropping process of the present invention is crucial for obtaining a stable and uniform resin product.

[0042] Performance Testing and Symbol Explanation: Thermal stability: Characterized using thermogravimetric analysis (TGA). In this paper, T... d5% The temperature at which a sample experiences a 5% mass loss under a nitrogen atmosphere is considered the optimal temperature. A higher temperature indicates better initial thermal decomposition stability of the resin. In this paper, T... d5% The test conditions were: nitrogen atmosphere, heating rate 10℃ / min.

[0043] Part Three: Examples of Preparation, Application, and Performance Testing of High Weather-Resistant Coatings Example 4: Preparation and properties of coating C1 (based on resin R1) 1. Coating preparation: In a high-speed disperser, add the following ingredients in the order of the formula and disperse until the fineness is ≤20μm.

[0044] Resin R1 (prepared in Example 1): 60.0 g Rutile titanium dioxide (R-706): 20.0 g Dispersant (BYK-163): 1.0 g Leveling agent (BYK-361N): 0.5 g Defoamer (BYK-052): 0.3 g Benzotriazole UV absorber (Tinuvin 1130): 0.5 g Propylene glycol methyl ether acetate (PMA): 12.0 g The above materials were dispersed at 2000 rpm for 15 minutes until the fineness was ≤20μm. Then, 10.0 g of HDI trimer (NCO content 19.6%) (calculated based on an NCO:OH molar ratio of 1.1) was added while stirring at 800 rpm. Stirring was continued for 10 minutes to ensure uniform mixing. Finally, the mixture was filtered through a 200-mesh filter cloth to obtain a white high-gloss coating, denoted as C1.

[0045] 2. Sample Preparation: Coating C1 was evenly applied using air spraying to tinplate (150mm×70mm) and anodized aluminum plate (100mm×100mm) that had been sanded, cleaned with acetone, and dried. The wet film thickness was controlled at approximately 100μm. After leveling at room temperature for 20 minutes, the samples were placed in a forced-air oven and cured at 80℃ for 30 minutes. The dry film thickness was controlled at 30±5μm. After curing for 7 days under standard conditions of 23±2℃ and 50±5% relative humidity, various performance tests were conducted.

[0046] 3. Performance test results: Standard physical and mechanical properties: 60° gloss 92; pencil hardness 2H; adhesion (cross-cut test, GB / T 9286) grade 0; impact resistance (GB / T 1732) 50 cm (no cracking or peeling in both forward and reverse impacts); bending test (GB / T 6742) through a 2 mm shaft.

[0047] Chemical resistance: The paint film shows no change after immersion in 10% sulfuric acid solution (25℃, 48h); it does not show the substrate after being washed with ethanol (1kg weight, GB / T 23989) more than 200 times.

[0048] Accelerated Weather Resistance (Core Test): Xenon lamp aging (GB / T 1865): After 1000 hours of continuous irradiation, the paint film retains 87% of its 60° gloss and has a color difference ΔE of 1.8. The paint film surface shows no chalking, cracking, or blistering.

[0049] Damp heat aging (GB / T 1740): After being placed at 40℃ and 98% relative humidity for 1000 hours, the paint film showed no blistering, no rusting, and no peeling, and the cross-cut adhesion remained at level 0.

[0050] Example 5: Preparation and properties of coating C2 (based on resin R2, suitable for metal corrosion protection) 1. Coating preparation: Resin R2 (prepared in Example 2): 65.0 g Composite zinc phosphate anti-rust pigment: 15.0 g Barium sulfate (filler): 10.0 g Additives (dispersant, leveling agent, defoamer): 2.0 g Mixed solvent (xylene: n-butanol = 8:2): 10.0 g Amino resin (Cymel 303, curing agent): 8.0 g Catalyst (10% isopropanol solution of p-toluenesulfonic acid): 0.5 g 2. Sample Preparation and Testing: The coating was sprayed onto the treated cold-rolled steel sheet and baked at 140℃ for 20 minutes. Test results: Initial gloss (60°) 90, pencil hardness H, adhesion grade 0. After 500 hours of neutral salt spray test (GB / T 1771), the width of the scratch on one side was <1.5mm, and there was no blistering or rust in the unscratched area. After 1000 hours of xenon lamp aging, the gloss retention rate was 82%, and the color difference ΔE was 2.3.

[0051] Example 6: Preparation and properties of coating C3 (based on resin R3, high-hardness outdoor application) 1. Coating preparation: Resin R3 (prepared in Example 3): 70.0 g Titanium dioxide: 18.0 g Additives: 2.0 g Solvent (PMA): 10.0 g HDI trimer curing agent: 12.0 g (NCO:OH=1.05) 2. Performance Characteristics: This coating exhibits higher hardness and fullness. The initial pencil hardness reaches 3H, and the bending test passes 2mm, demonstrating an excellent balance between hardness and toughness. Weather Resistance Test: After 1000 hours of xenon lamp aging, the gloss retention rate is 85%, and the color difference ΔE is 2.0.

[0052] Comparative coating preparation (for comparison) Comparative coatings were prepared using resins D1, D2, D3, and D4, respectively, strictly following the coating formulation (only the resin was replaced), preparation process, and curing conditions of Example 4, and were labeled as CD1, CD2, CD3, and CD4 accordingly.

[0053] Part Four: Comprehensive Performance Comparison Analysis The coatings of this invention (C1, C2, C3) and comparative coatings (CD1-CD4) were tested in parallel, and the key weather resistance data are summarized in Table 2 below: Table 2: Comprehensive Comparison of Accelerated Aging Performance of Coatings

[0054] Overall conclusion: Through the above systematic, detailed embodiments and comparative experiments, the following conclusions can be clearly drawn: 1. Necessity and Preferred Optimality of Functional Monomer II: Comparing C1 with CD1 and CD4, the introduction of specific functional monomer II (isobornyl ester, vinyl benzoate) is the decisive factor in obtaining high weather resistance. Comparing C1 with CD2, it is demonstrated that isobornyl ester is significantly superior to the structurally similar cyclohexyl ester, reflecting the inventiveness of the monomer selection in this invention.

[0055] 2. The crucial role of the stepwise dripping process: Compared to C1 and CD3, the stepwise dripping process is essential for constructing a gradient structure and balancing the hardness and flexibility (impact resistance, bending resistance) of the paint film. The single-stage dripping process (CD3) results in a brittle paint film and reduced adhesion, proving that this process is an indispensable part of this solution.

[0056] 3. Synergistic effect and unexpected technical results: This invention combines "specific functional monomer II" with "stepwise dripping process" to prepare acrylic resin and its coatings under normal pressure and without using expensive fluorine / silicon monomers. The resulting products achieve synergistic improvement in weather resistance (gloss and color retention) and comprehensive mechanical properties, achieving excellent results far exceeding those of ordinary resins and single improvement methods. This effect is unexpected.

[0057] 4. Completeness and industrial applicability of the technical solution: The technical solution of the present invention is complete and clear. From resin synthesis to coating formulation and performance characterization, detailed and repeatable embodiments are provided, which fully demonstrates its industrial applicability.

[0058] The embodiments described above are merely for illustrating the technical solutions of the present invention more clearly, and are not intended to limit the scope of protection thereof. Any conventional adjustments or optimizations made to the type, dosage ratio, and process parameters of monomers within the core technical concept of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high weather-resistant, atmospheric-pressure polymerizable acrylic resin, characterized in that, It is prepared by free radical polymerization of monomer raw materials comprising the following parts by weight: (a) 30-50 parts of hard monomer, selected from at least one of methyl methacrylate, styrene, and acrylonitrile; (b) 15-35 parts of soft monomer, selected from at least one of butyl acrylate, 2-ethylhexyl acrylate, and isooctyl acrylate; The weight ratio of the hard monomer (a) to the soft monomer (b) is 1.5:1 to 2.5:

1. (c) 2-8 parts of functional monomer I, wherein functional monomer I is a monomer containing an active cross-linking functional group, selected from at least one of (meth)acrylate, (meth)acrylate, acrylamide, and N-hydroxymethylacrylamide; (d) 5-15 parts of functional monomer II, wherein functional monomer II is at least one selected from isobornyl methacrylate or vinyl benzoate; (e) 1-5 parts of unsaturated carboxylic acid monomers, selected from at least one of acrylic acid, methacrylic acid, and itaconic acid; In addition, based on the total weight parts of the monomer raw materials, there are 0.2-2 parts of initiator and 40-60 parts of organic solvent; The resin is prepared from the monomer raw material by a method comprising the following steps: S1. Premixing: Mix all of the monomers (a)-(e), 30-50% of the total amount of the initiator, and 50-70% of the total amount of the organic solvent to obtain a mixed monomer liquid; S2. First step of dropwise polymerization: Under normal pressure and reflux conditions of 110-140℃, the first part of the mixed monomer liquid, which accounts for 60-80% of the total amount of the mixed monomer liquid, is added dropwise to the reaction system containing the remaining organic solvent over 2-4 hours. After the addition is completed, the reaction is kept at the temperature for 0.5-1.5 hours. S3. Second step of dropwise polymerization: The second part of the mixed monomer liquid, accounting for 20-40% of the total amount of the mixed monomer liquid, and the remaining initiator are added dropwise to the reaction system over 1-2 hours, and then the temperature is raised to 135-145℃ and kept at the temperature for 2-4 hours. S4. Post-processing: After the reaction is complete, cool down and discharge the material.

2. The high weather-resistant, atmospheric-pressure polymerizable acrylic resin according to claim 1, characterized in that, The functional monomer II is isobornyl methacrylate.

3. The high weather-resistant, atmospheric-pressure polymerizable acrylic resin according to claim 1, characterized in that, The functional monomer II is vinyl benzoate.

4. A high weather-resistant coating, characterized in that, It contains the following components in parts by weight: 50-70 parts of the high weather-resistant, atmospheric-pressure polymerized acrylic resin as described in any one of claims 1-3; 15-30 parts of pigments and fillers; 5-15 parts of curing agent; 1-5 parts of auxiliary agent; Solvent 10-20 parts.

5. The high weather-resistant coating according to claim 4, characterized in that, When the high weather-resistant, atmospheric-pressure polymerized acrylic resin contains hydroxyl functional groups, the curing agent is an isocyanate curing agent; when the high weather-resistant, atmospheric-pressure polymerized acrylic resin contains epoxy functional groups, the curing agent is an amino resin or a polybasic acid curing agent.

6. A method for preparing a high weather-resistant coating according to claim 4 or 5, characterized in that, include: Mix all components, disperse evenly, and filter to obtain the final product.

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