Preparation method of modified acrylic resin and application thereof

Abstract

The present application relates to the technical field of resin coating, and particularly relates to a preparation method of modified acrylic resin and application thereof, which comprises the following steps: firstly, hydrolysis and condensation of multiple organosilicon alkoxyl monomers, then grafting with epoxy resin to obtain organosilicon-epoxy resin containing vinyl; subsequently, under the protection of nitrogen, a premixed solution of styrene, multiple acrylate monomers, initiator and solvent is added dropwise into a reaction kettle containing the resin, and after polymerization by staged heat preservation, parameters are adjusted to obtain the modified acrylic resin. The resin has a ternary hybrid structure of acrylic acid, epoxy and organosilicon through grafting, condensation and copolymerization, and has good film forming property, high adhesion, excellent high temperature resistance and flexibility. The coating prepared by using the resin can realize normal temperature self-drying, and the coating layer is dense and smooth, has strong adhesion, good corrosion resistance and impact resistance, and can withstand high temperature and cold cycle, and is suitable for protection of parts which need long-term high temperature and corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of resin coating technology, and in particular to a method for preparing a modified acrylic resin and its application. Background Technology

[0002] Acrylic resins are widely used in coatings, adhesives, and other fields due to their excellent film-forming properties, weather resistance, and decorative properties. However, traditional acrylic resins have significant shortcomings in high-temperature resistance. The carbon-carbon bonds and ester bonds in their structure are prone to breakage or oxidative decomposition at high temperatures, leading to coating loss of gloss, yellowing, and even cracking, limiting their application in high-temperature conditions, such as the protection of high-temperature components like metallurgical equipment, engine housings, and chimneys. To improve heat resistance, the industry often attempts to introduce silicone resins. Silicone resins have a main chain composed of silicon-oxygen bonds with high bond energy and good thermal stability. However, whether silicone resins are cold-blended or thermally grafted with acrylic resins, the mechanical strength, corrosion resistance, and adhesion of the coating are often not ideal.

[0003] On the other hand, epoxy resin is known for its excellent adhesion and chemical resistance, and is often used as an anti-corrosion primer. However, epoxy resin itself also has limited high-temperature resistance and is prone to thermal degradation at high temperatures. To achieve good high-temperature anti-corrosion effects, the amount of silicone resin and epoxy resin is usually relatively high when modifying acrylic resin. However, the compatibility between silicone resin and epoxy resin, and between acrylic resin and epoxy resin, is generally poor. Especially when the amount of low molecular weight epoxy resin and silicone resin is high, if acrylic resin, epoxy resin and silicone resin are simply physically mixed, the system is prone to phase separation due to differences in molecular polarity and compatibility, making it impossible to form a uniform and stable coating, and the performance of each component cannot achieve synergistic effect. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for preparing modified acrylic resin and its application. Styrene and acrylate monomers are used as comonomers to copolymerize with vinyl-containing silicone-epoxy resins, constructing a ternary hybrid structure of acrylic, epoxy, and silicone. This solves the technical problems of insufficient performance of single resins and poor compatibility of simple blends, making it difficult to simultaneously possess excellent high-temperature resistance, high adhesion, and high corrosion resistance. Specifically, this is achieved through the following technical solution.

[0005] First, the present invention provides a method for preparing a modified acrylic resin, specifically including the following steps:

[0006] Step 1: Preparation of vinyl-containing organosilicon-epoxy resin

[0007] S1: Stir and mix the epoxy resin with the first solvent to form an epoxy resin mixture;

[0008] S2: Mix various organosiloxane monomers containing vinyltrimethoxysilane with deionized water, add a hydrolysis catalyst to carry out a hydrolysis reaction, and generate a low molecular weight prepolymer.

[0009] S3: Mix the epoxy resin mixture with the low molecular weight prepolymer, add a grafting catalyst to react, and obtain a vinyl-containing organosilicon-epoxy resin.

[0010] Second step: Preparation of modified acrylic resin

[0011] Step 1: Mix styrene, acrylate monomer, initiator, and second solvent to form a premix;

[0012] Step 2: Add the vinyl-containing silicone-epoxy resin obtained in the first step to the reactor, introduce nitrogen gas and heat to 100-150°C, then add the premixed liquid dropwise into the reactor at a uniform rate for 1-3 hours;

[0013] Step 3: After the droplet addition is completed, keep the reaction at a constant temperature, add the initiator and solvent, and keep the reaction at 100-150℃ for 3-5 hours. Finally, cool down and add solvent to adjust the solid content to 49%-51%, the viscosity to 200-800 mPa·s, and the acid value to 2-5 mgKOH / g to obtain the modified acrylic resin.

[0014] Preferably, in step S1 of the first step, the epoxy resin is at least one of E-44 epoxy resin, E-20 epoxy resin, and E-12 epoxy resin; and the first solvent is at least two of xylene, propylene glycol methyl ether acetate, cyclohexanone, and methyl isobutyl ketone.

[0015] Preferably, in step S2 of the first stage, the plurality of organosiloxane monomers further include at least two of methyltrimethoxysilane, phenyltrimethoxysilane, dimethyldiethoxysilane, and diphenyldimethoxysilane.

[0016] Preferably, in step S2 of the first stage, the hydrolysis catalyst is at least one of hydrochloric acid, hydrofluoric acid, and p-toluenesulfonic acid.

[0017] Preferably, in step 1 of the second step, the acrylate monomer is selected from at least four of the following: butyl acrylate, butyl methacrylate, methyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, hydroxyethyl methacrylate phosphate, and acrylic acid.

[0018] Preferably, in step 1 of the second step, the second solvent is at least one of butyl acetate, n-butanol, xylene, and propylene glycol methyl ether; and the initiator is at least one of tert-butyl peroxide, tert-butyl perethylhexanoate, and di-tert-butyl peroxide.

[0019] Secondly, this invention also provides an application of modified acrylic resin in the preparation of high-temperature resistant and corrosion-resistant coatings, specifically including the following steps:

[0020] Step A. Preparation of slurry: Mix the modified acrylic resin, dispersant, diluent, pigments and fillers evenly, and grind until the fineness is ≤20μm to obtain the slurry;

[0021] Step B. Preparation of coating: The modified acrylic resin, the slurry obtained in step A, the wetting and leveling agent, the defoamer, and the diluent are stirred and mixed evenly to prepare a high-temperature resistant anti-corrosion coating.

[0022] Preferably, in step A, the dispersant is Disponer 983, and the pigments and fillers include copper chromate black, talc, glass powder, and zinc phosphate.

[0023] Preferably, in step A, the mass ratio of the modified acrylic resin, dispersant, diluent, pigment, and filler is 30-50:1-5:1-5:40-70.

[0024] Preferably, in step B, the wetting and leveling agent is BYK310 and the defoamer is BYK052;

[0025] The mass ratio of the modified acrylic resin, slurry, wetting and leveling agent, defoamer, and diluent is 20-40:50-80:0.3-1:0.1-0.5:5-10.

[0026] After adopting the above technical solution, the beneficial effects of the present invention are:

[0027] 1. By copolymerizing vinyl-containing silicone-epoxy resin with acrylate monomers, a ternary graft structure in which acrylic resin segments, epoxy resin segments, and silicone segments are bonded to each other is successfully constructed on the molecular chain. This solves the compatibility problem among acrylic resin, silicone resin, and epoxy resin, and makes the coating have excellent film-forming properties, high adhesion, and excellent high-temperature resistance, overcoming the performance limitations of single resins or simple physical blends.

[0028] 2. The prepared modified acrylic resin has a uniform and stable microstructure, good compatibility with various pigments, fillers and additives, and the coating system made from it is stable in dispersion and does not easily settle or separate during storage. The paint film formed after construction is dense and smooth with a smooth appearance and no defects such as pinholes, orange peel, or color difference. It has both excellent decorative and protective properties.

[0029] 3. The high-temperature resistant and anti-corrosion coating prepared from this resin exhibits excellent comprehensive performance. It can be cured at room temperature, has strong adhesion, high hardness, and good impact resistance. It can also withstand long-term high temperature and thermal cycling tests without cracking or peeling. At the same time, it has good corrosion resistance and is suitable for harsh industrial protection environments. Detailed Implementation

[0030] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the invention.

[0031] The present invention provides a method for preparing a modified acrylic resin and its application, wherein the method for preparing the modified acrylic resin specifically includes the following steps:

[0032] Step 1

[0033] Styrene, acrylate monomers, initiators and solvents are mixed evenly to form a premix for later use;

[0034] The acrylate monomers are at least four of the following: butyl acrylate, butyl methacrylate, methyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, hydroxyethyl methacrylate phosphate, and acrylic acid.

[0035] The solvent is at least one of butyl acetate, n-butanol, xylene, and propylene glycol methyl ether.

[0036] The initiator is at least one of tert-butyl peroxide, tert-butyl peroxide, and di-tert-butyl peroxide.

[0037] The mass ratio of added styrene, acrylate monomer, initiator, and solvent is 30-40:70-110:1.5-2.5:20-30.

[0038] The styrene added in the above steps is a hard monomer. The benzene ring in its molecular structure has rigid characteristics, which can significantly improve the glass transition temperature, mechanical strength and chemical corrosion resistance of the final resin. In addition, the amount of added components is small, so as to avoid affecting the overall flexibility of the composition.

[0039] The above-mentioned initiators are all oil-soluble free radical initiators, which can initiate monomer polymerization under certain temperature conditions. By using four or more acrylate monomers, the key properties of the resin, such as hardness, flexibility, and adhesion, are balanced through multi-component synergy, avoiding performance shortcomings caused by single or few monomers.

[0040] This stage is a purely physical mixing process without any chemical reaction. However, care must be taken during the mixing process. First, add the solvent to create a dissolving environment to avoid local aggregation caused by differences in solubility when directly mixing monomers. Then, add the initiator to prevent premature decomposition of the initiator in high-concentration monomers. This ensures that the premixed solution remains stable before being added. A stable premixed solution is less likely to separate or precipitate in subsequent steps, improving production efficiency and reducing production waste caused by premixed solution issues, thus lowering costs.

[0041] Step 2

[0042] Add the vinyl-containing silicone-epoxy resin to the reactor, introduce nitrogen gas as a protective gas, and heat to 100-150°C. Then, add the premixed liquid obtained in step 1 to the reactor dropwise at a uniform rate for 1-3 hours.

[0043] The mass ratio of the added vinyl-containing silicone-epoxy resin to the premixed liquid is 400-550:122-165.

[0044] The vinyl-containing silicone-epoxy resin used in the above steps is a key component for modifying acrylic resin to achieve high temperature resistance and high adhesion. The specific details of its preparation process determine the final modification effect.

[0045] The preparation method of vinyl-containing organosilicon-epoxy resin includes the following steps:

[0046] S1: Stir and mix the epoxy resin and solvent evenly to form an epoxy resin mixture for later use.

[0047] The epoxy resin is at least one of E-44 epoxy resin, E-20 epoxy resin, and E-12 epoxy resin.

[0048] The solvent is at least two of xylene, propylene glycol methyl ether acetate, cyclohexanone, and methyl isobutyl ketone.

[0049] The mass ratio of added epoxy resin to solvent is 2 to 3:3.

[0050] The epoxy resins used in the above steps have different epoxy values. E-44 has a higher epoxy value and stronger reactivity, which can improve the grafting efficiency with organosilicon. E-20 and E-12 have lower epoxy values, which can reduce the resin crosslinking density and avoid coating embrittlement. By mixing epoxy resin and solvent within a certain proportion range, the uniform mixing of organosilicon components can be effectively controlled, and the efficiency of subsequent grafting reactions can be guaranteed.

[0051] This step transforms solid epoxy resin into a homogeneous liquid system. On the one hand, it reduces viscosity, providing good flowability for subsequent mixing with organosilicon hydrolysis products and avoiding uneven mixing caused by excessive resin viscosity. On the other hand, by adjusting the material compatibility and solid content through solvent, it provides a suitable concentration environment for the grafting reaction, ensuring the contact probability between epoxy groups and silanol groups, increasing the grafting rate while preventing excessive polycondensation of organosilicon.

[0052] S2: Mix the organosilaneoxy monomer with deionized water and then put it into the reactor. Add the hydrolysis catalyst to the reactor. After the exothermic reaction stops, continue heating to 50-70℃ and keep the temperature for 2-5 hours.

[0053] The organosiloxane monomer is at least three of vinyltrimethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, dimethyldiethoxysilane, and diphenyldimethoxysilane.

[0054] The hydrolysis catalyst is at least one of hydrochloric acid, hydrofluoric acid, and p-toluenesulfonic acid, and the mass percentage concentration of the hydrolysis catalyst is an aqueous solution of 1.0% to 6.0%.

[0055] In the above steps, the mass ratio of the mixed organosiloxane monomer to deionized water is 45-50:4-6.

[0056] In the above steps, the mass ratio of the amount of hydrolysis catalyst added to deionized water is 4-6:20-30.

[0057] In the above steps, the performance of the organosilicon chain can be precisely controlled by the combination of various organosilicon monomers and the type and ratio of monomers. For example, vinyltrimethoxysilane is the core functional monomer, and the vinyl group in its molecule can serve as the active site for subsequent copolymerization with acrylic monomers. Trimethoxysilane provides sites for hydrolysis. Methyltrimethoxysilane and dimethyldiethoxysilane can introduce methyl and dimethyl groups, thereby improving hydrophobicity and flexibility. Phenyltrimethoxysilane and diphenyldimethoxysilane can introduce phenyl and diphenyl groups, thereby improving high temperature resistance.

[0058] In this step, silanoxy groups are converted into silanol groups through hydrolysis, providing active sites for subsequent reactions with epoxy groups of epoxy resin; at the same time, some silanol groups undergo condensation reactions, removing one molecule of water to form Si-O-Si bonds and generate oligomeric siloxanes; in addition, this reaction process retains vinyl groups, laying the foundation for subsequent copolymerization reactions with acrylic resin.

[0059] In this step, by controlling the reaction temperature and the degree of hydrolysis and condensation, a low molecular weight prepolymer with good compatibility with epoxy resin is generated. At the same time, the introduction of different silane monomers can endow the organosilicon segments with specific functions at the molecular level.

[0060] S3: Add the epoxy resin mixture obtained in step S1 to the reactor, rinse the container and pipes with a small amount of solvent, stir evenly and then add the grafted catalyst. Heat to 100-150°C for 2-4 hours, separate the alcohol generated in the reaction, keep warm for 2-3 hours and then check that the coating is transparent to obtain the vinyl-containing organosilicon-epoxy resin product.

[0061] The mass ratio of epoxy resin mixture to rinsing solvent is 25-30:3-4.

[0062] The grafting catalyst is a solution formed by dissolving one of dibutyltin dilaurate, dioctyltin dilaurate, or dibutyltin oxide in a solvent, and the solvent is one of cyclohexanone, methyl isobutyl ketone, or propylene glycol methyl ether acetate.

[0063] The grafted catalyst has a mass percentage concentration of 0.1% to 0.5%, and the mass ratio of epoxy resin mixture to grafted catalyst is 250 to 300: 5 to 15.

[0064] In the above reaction process, the tin atoms in the graft catalyst form a coordination complex with the epoxy groups of the epoxy resin, which redistributes the electron cloud density of the epoxy ring. The epoxy ring is more easily attacked by hydrogen atoms in the silanol group, resulting in ring opening of the epoxy ring and the formation of hydroxyl intermediates. This achieves the grafting of organosilicon segments and epoxy resin. At the same time, condensation reaction occurs between the silanol groups to form Si-O-Si bonds, which are further crosslinked to construct an epoxy resin and organosilicon block hybrid structure.

[0065] The above process, through grafting and polycondensation reactions, forms a hybrid resin that combines the high adhesion of epoxy resin with the high temperature resistance of organosilicon, providing a core component for the subsequent high-performance modification of acrylic resin.

[0066] In addition, during the above reaction process, the vinyl groups on the organosilicon segments do not participate in the reaction and are thus preserved intact, providing active sites for the subsequent free radical copolymerization reaction with acrylic resin, ensuring the formation of the ternary hybrid structure.

[0067] The vinyl-containing silicone-epoxy resin prepared by the above method has excellent high-temperature resistance, which lays the foundation for the high-temperature resistance of the coatings prepared subsequently. Furthermore, the vinyl-containing silicone-epoxy resin prepared by the above method has good compatibility with acrylic resin, which can avoid defects such as pinholes in the final coating appearance caused by compatibility differences.

[0068] Step 3

[0069] After the addition is complete, the reaction is kept at a constant temperature for 0.5 to 1 hour. Initiator and solvent are added to the reaction vessel. After the addition is complete, the reaction is kept at a constant temperature of 100 to 150°C for 3 to 5 hours. The temperature is then lowered to below 80°C. Solvent is added to adjust the solid content to 49% to 51%, the viscosity to 200 to 800 mPa·s, and the acid value to 2 to 5 mg KOH / g, thus preparing a modified acrylic resin.

[0070] The initiator is at least one of tert-butyl peroxide, tert-butyl peroxide, and di-tert-butyl peroxide.

[0071] The solvent used in the above steps is at least one of butyl acetate, n-butanol, xylene, and propylene glycol methyl ether.

[0072] The mass ratio of the initiator and solvent added in the above steps to the initiator added in step 2 is 3-5:1:20.

[0073] The above reaction process is completed in two stages. The first stage is the prepolymerization stage, in which the premixed liquid is added dropwise to the reactor containing organosilicon-epoxy resin, allowing the initiator in the premixed liquid to decompose slowly and generate a small amount of free radicals, which initiate the initial polymerization of styrene and acrylate monomers to form a low molecular weight acrylic acid prepolymer. The second stage is the full copolymerization stage, in which the added initiator provides sufficient free radicals for the polymerization reaction, ensuring that the acrylic acid prepolymer and the vinyl groups in the organosilicon-epoxy resin undergo full copolymerization. The added solvent can adjust the viscosity of the system. The reaction is carried out at 100-150°C for 3-5 hours to ensure that the copolymerization reaction is complete.

[0074] In the above steps, the weather resistance of acrylic resin, the adhesion and corrosion resistance of epoxy resin, and the high-temperature resistance of silicone are integrated through copolymerization to form a ternary hybrid structure. Compared with traditional acrylic resin, the modified acrylic resin has excellent high-temperature resistance, high adhesion, good flexibility, and corrosion resistance, avoiding the performance defects of single resins and meeting the comprehensive performance requirements of high-temperature anti-corrosion coatings.

[0075] This process involves staged polymerization and post-treatment to control the resin's molecular weight, molecular weight distribution, solid content, viscosity, and acid value, ensuring good compatibility between the resin and other components in the subsequent coating preparation, while also meeting the requirements of different construction methods.

[0076] In addition, staged polymerization can avoid problems such as violent exothermic reactions and sudden increases in viscosity during the reaction process, reduce process risks, and adjust performance parameters in post-processing can make up for minor fluctuations in the early reaction, ensuring consistent performance of resins in different batches and improving the production qualification rate.

[0077] Compared with traditional acrylic resins, the modified acrylic resin prepared by the above method has excellent high temperature resistance, high adhesion, good flexibility and corrosion resistance. In addition, its solid content, viscosity and acid value are stable, and it is compatible with a variety of pigments, fillers and additives. It is suitable for various construction methods such as brushing, spraying and rolling, and meets the construction needs of different working conditions.

[0078] The modified acrylic resin prepared using the above method is used to prepare a high-temperature resistant and corrosion-resistant coating, specifically including the following steps:

[0079] Step A. Preparation of black paste

[0080] The modified acrylic resin, Disponer 983 dispersant, xylene, copper chromate black, talc, glass powder, and zinc phosphate prepared by the above method are mixed evenly and ground until the average particle size is ≤20μm to obtain a black slurry.

[0081] The mass ratio of the added modified acrylic resin, Disponer 983 dispersant, xylene, copper chromate black, talc, glass powder, and zinc phosphate is 30-50:1-5:1-5:20-30:10-20:5-10:5-10.

[0082] During the above steps, the pigments and fillers are evenly dispersed in the resin through grinding and dispersant action, avoiding agglomeration and ensuring that the coating's hiding power and color uniformity meet the standards. The uniform black slurry can be quickly mixed with subsequent resins and additives, avoiding coating layering and color differences caused by slurry instability, reducing the mixing time before coating use, and improving construction efficiency.

[0083] In addition, controlling the fineness of the slurry to ≤20μm can make the coating surface smooth and flat after spraying, without defects such as graininess and pinholes, thus meeting the decorative requirements. It can also ensure that the coating's hiding power, high temperature resistance, and corrosion resistance all meet the design requirements, avoiding functional failure caused by pigment and filler agglomeration.

[0084] Step B. Preparation of anti-corrosion coating

[0085] Modified acrylic resin, black slurry, BYK310 wetting and leveling agent, BYK052 defoamer, and xylene are thoroughly mixed to prepare a high-temperature resistant anti-corrosion coating.

[0086] The mass ratio of the added modified acrylic resin, black slurry, BYK310 wetting and leveling agent, BYK052 defoamer, and xylene is 20-40:50-80:0.3-1:0.1-0.5:5-10.

[0087] In this process, the added modified acrylic resin serves as the main film-forming substance in the coating. Its function is to encapsulate, bond, and integrate the pigments, fillers, and additives in the black slurry to form a continuous and dense coating.

[0088] BYK310 wetting and leveling agent is a polyether-modified polysiloxane leveling agent. Its function is to reduce the surface tension of the coating, improve the wettability of the coating to the substrate, avoid pinholes and craters caused by poor wetting, and promote the flow and spread of the coating on the substrate surface, reduce defects such as pinholes and brush marks, and improve the smoothness of the coating.

[0089] BYK052 defoamer is a mineral oil and polysiloxane composite defoamer. It prevents the formation of new foam by forming a monolayer on the coating surface. In addition, the defoamer particles can penetrate the foam film, destroy the elasticity of the film, and cause the formed foam to break.

[0090] Xylene, as a diluent, can adjust the viscosity of the coating to the range required for application, ensuring good atomization of the coating and preventing problems such as sagging and dry spraying.

[0091] After the coating is applied, under normal temperature or low temperature baking conditions, the solvent xylene gradually evaporates, and the resin molecules approach each other. Through intermolecular forces, a continuous and dense cross-linked coating is formed, fixing the pigments and fillers in the coating and forming a protective film that combines decoration and functionality.

[0092] To facilitate understanding of the present invention, several embodiments and comparative examples are given below.

[0093] Example 1

[0094] Step 1: Preparation of vinyl-containing organosilicon-epoxy resin

[0095] S1: Mix 150g of E-20 epoxy resin with 50g of methyl isobutyl ketone and 100g of xylene to form an epoxy resin mixture for later use.

[0096] S2: Mix 40g of methyltrimethoxysilane, 125g of phenyltrimethoxysilane, 50g of dimethyldiethoxysilane, 25g of diphenyldimethoxysilane, 25g of vinyltrimethoxysilane and 24g of deionized water evenly and put them into the reaction vessel. Add 4.25g of 5.0% p-toluenesulfonic acid aqueous solution to the reaction vessel. After the exothermic reaction stops, continue heating to 67°C and keep the reaction at this temperature for 3 hours.

[0097] S3: Add the epoxy resin mixture obtained in step S1 to the reactor, rinse the container and pipes with 40g xylene, stir evenly, add 10.0g of methyl isobutyl ketone solution with a mass percentage concentration of 1.0% dioctyltin dilaurate, heat to 118℃ for 3 hours, and at the same time separate 110g of the alcohol generated in the reaction. After keeping warm for 3 hours, check that the coating is transparent, and obtain a vinyl-containing organosilicon-epoxy resin product with a solid content of 64.2%.

[0098] Second step: Preparation of modified acrylic resin

[0099] Step 1

[0100] Mix 30g styrene, 35g methyl methacrylate, 30g butyl methacrylate, 4.5g lauryl methacrylate, 1g acrylic acid, 1g hydroxyethyl methacrylate phosphate, 1.5g tert-butyl diethylhexanoate and 20g propylene glycol methyl ether evenly to form a premix for later use.

[0101] Step 2

[0102] Add 500g of vinyl-containing silicone-epoxy resin to the reactor, introduce nitrogen gas as a protective gas, and heat to 118°C. Then, add the premixed liquid obtained in step 1 to the reactor at a uniform rate over a period of 1.5 hours.

[0103] Step 3

[0104] After the addition was complete, the reaction was kept at a constant temperature for 0.5 hours. Then, 0.5 g of tert-butyl diethylhexanoate and 10 g of propylene glycol methyl ether were added to the reactor. After the addition was complete, the reaction was kept at a constant temperature for 4 hours. The temperature was then lowered to below 80°C, and 150 g of butyl acetate and 65 g of propylene glycol methyl ether were added to dilute the mixture, resulting in a modified acrylic resin with a solid content of 49.8%, a viscosity of 490 mPa·s, and an acid value of 2.1 mg KOH / g.

[0105] Third step: Preparation of high-temperature resistant and corrosion-resistant coating

[0106] Step A. Preparation of black paste

[0107] 40g of modified acrylic resin, 2g of Disponer983 dispersant, 2g of xylene, 25g of copper chromate black, 15g of talc, 10g of glass powder, and 6g of zinc phosphate prepared by the above method were mixed evenly and ground to a fineness of 18μm to obtain a black slurry.

[0108] Step B. Preparation of anti-corrosion coating

[0109] 35g of modified acrylic resin, 60g of black slurry, 0.3g of BYK310 wetting and leveling agent, 0.2g of BYK052 defoamer, and 4.2g of xylene were thoroughly mixed to prepare a high-temperature resistant anti-corrosion coating.

[0110] Example 2

[0111] Step 1: Preparation of vinyl-containing organosilicon-epoxy resin

[0112] S1: Mix 100g of E-12 epoxy resin with 50g of cyclohexanone and 100g of propylene glycol methyl ether acetate to form an epoxy resin mixture for later use.

[0113] S2: Mix 100g phenyltrimethoxysilane, 75g dimethyldiethoxysilane, 50g diphenyldimethoxysilane, 25g vinyltrimethoxysilane and 20g deionized water evenly and put them into the reaction vessel. Add 5.2g of 1.5% hydrochloric acid aqueous solution to the reaction vessel. After the exothermic reaction stops, continue heating to 60-64℃ and keep the reaction at this temperature for 5 hours.

[0114] S3: Add the epoxy resin mixture obtained in step S1 to the reactor. Rinse the container and pipes with 30g of propylene glycol methyl ether acetate. After stirring evenly, add 10.0g of cyclohexanone solution with a mass percentage concentration of 0.50% dibutyltin dilaurate. Heat to 122℃ for 3 hours. At the same time, separate 100g of the alcohol generated in the reaction. After keeping warm for 2.5h, check that the coating is transparent to obtain a vinyl-containing organosilicon-epoxy resin product with a solid content of 60.3%.

[0115] Second step: Preparation of modified acrylic resin

[0116] Step 1

[0117] Mix 35g styrene, 60g methyl methacrylate, 30g butyl acrylate, 5g lauryl methacrylate, 10g cyclohexyl methacrylate, 2g acrylic acid, 1g hydroxyethyl methacrylate phosphate, 1g tert-butyl diethylhexanoate, 1g tert-butyl peroxide, and 20g n-butanol evenly to form a premix for later use.

[0118] Step 2

[0119] Add 400g of vinyl-containing silicone-epoxy resin to the reactor, introduce nitrogen gas as a protective gas, and heat to 122°C. Then, add the premixed liquid obtained in step 1 dropwise to the reactor at a uniform rate for 2 hours.

[0120] Step 3

[0121] After the addition was complete, the reaction was kept at a constant temperature for 0.5 hours. Then, 0.5 g of tert-butyl diethylhexanoate and 10 g of n-butanol were added to the reactor. After the addition was complete, the reaction was kept at a constant temperature for 3 hours. The temperature was then lowered to below 110°C, and 195 g of butyl acetate was added to dilute the mixture. This yielded a modified acrylic resin with a transparent coating, a resin solid content of 50.1%, a viscosity of 635 mPa·s, and an acid value of 3.2 mgKOH / g.

[0122] Third step: Preparation of high-temperature resistant and corrosion-resistant coating

[0123] Step A. Preparation of black paste

[0124] The modified acrylic resin, 3g Disponer 983 dispersant, 12g xylene, 15g copper chromate black, 15g talc, 10g glass powder, and 10g zinc phosphate prepared by the above method were mixed evenly and ground until the average particle size was 18μm to obtain a black slurry.

[0125] Step B. Preparation of anti-corrosion coating

[0126] 40g of modified acrylic resin, 50g of black slurry, 0.35g of BYK310 wetting and leveling agent, 0.15g of BYK052 defoamer, and 4.5g of xylene were thoroughly mixed to prepare a high-temperature resistant anti-corrosion coating.

[0127] Example 3

[0128] Step 1: Preparation of vinyl-containing organosilicon-epoxy resin

[0129] S1: Mix 50g of E-20 epoxy resin, 100g of E-44 epoxy resin, 50g of propylene glycol methyl ether acetate, and 100g of xylene to form an epoxy resin mixture for later use.

[0130] S2: Mix 75g of methyltrimethoxysilane, 100g of phenyltrimethoxysilane, 25g of diphenyldimethoxysilane, 25g of vinyltrimethoxysilane and 30g of deionized water evenly and put them into a reaction vessel. Add 5.2g of 2.0% hydrofluoric acid aqueous solution to the reaction vessel. After the exothermic reaction stops, continue heating to 56-60℃ and keep the reaction at this temperature for 4 hours.

[0131] S3: Add the epoxy resin mixture obtained in step S1 to the reactor. Rinse the container and pipes with 40g of propylene glycol methyl ether acetate. After stirring evenly, add 10.0g of a 0.50% (w / w) dibutyltin dilaurate propylene glycol methyl ether acetate solution. Heat to 112℃ for 3 hours, while separating 130g of the alcohol generated in the reaction. After maintaining the temperature for 2 hours, check that the coating is transparent, obtaining a vinyl-containing organosilicon-epoxy resin product with a solid content of 64.5%. A vinyl-containing organosilicon-epoxy resin product is obtained.

[0132] Second step: Preparation of modified acrylic resin

[0133] Step 1

[0134] Mix 40g styrene, 65g methyl methacrylate, 10g lauryl methacrylate, 5g cyclohexyl methacrylate, 2g acrylic acid, 1g hydroxyethyl methacrylate phosphate, 1.5g tert-butyl peroxide, 1g di-tert-butyl peroxide and 20g propylene glycol methyl ether evenly to form a premix for later use.

[0135] Step 2

[0136] Add 550g of vinyl-containing silicone-epoxy resin to the reactor, introduce nitrogen gas as a protective gas, and heat to 134-138℃. Then, add the premixed liquid obtained in step 1 to the reactor at a uniform rate for 1 hour.

[0137] Step 3

[0138] After the addition was complete, the reaction was kept at a constant temperature for 1 hour. Then, 0.5 g of tert-butyl peroxide and 10 g of propylene glycol methyl ether were added to the reactor. After the addition was complete, the reaction was kept at a constant temperature for 4 hours. The temperature was then lowered to below 110°C, and 200 g of butyl acetate and 55 g of propylene glycol methyl ether were added to dilute the mixture. This yielded a modified acrylic resin with a transparent coating, a resin solid content of 50.3%, a viscosity of 265 mPa•s, and an acid value of 2.6 mgKOH / g.

[0139] Third step: Preparation of high-temperature resistant and corrosion-resistant coating

[0140] Step A. Preparation of black paste

[0141] 45g of modified acrylic resin, 3g of Disponer983 dispersant, 2g of xylene, 20g of copper chromate black, 15g of talc, 10g of glass powder, and 5g of zinc phosphate prepared by the above method were mixed evenly and ground until the average particle size was 18μm to obtain a black slurry.

[0142] Step B. Preparation of anti-corrosion coating

[0143] 30g of modified acrylic resin, 60g of black slurry, 0.2g of BYK310 wetting and leveling agent, 0.1g of BYK052 defoamer, and 9.7g of xylene were thoroughly mixed to prepare a high-temperature resistant anti-corrosion coating.

[0144] Comparative Example 1

[0145] This comparative example is based on Example 1, except that step 3 of the first step, which involves preparing the vinyl-containing organosilicon-epoxy resin, is omitted. After step 2 is completed, the temperature is increased to separate an equal amount of alcohol from step 3, which is then mixed evenly with the epoxy resin solution from step 1. The second and third steps are then performed sequentially, specifically as follows:

[0146] Second step: Preparation of modified acrylic resin

[0147] Step 1

[0148] Mix 30g styrene, 35g methyl methacrylate, 30g butyl methacrylate, 4.5g lauryl methacrylate, 1g acrylic acid, 1g hydroxyethyl methacrylate phosphate, 1.5g tert-butyl diethylhexanoate and 20g propylene glycol methyl ether evenly to form a premix for later use.

[0149] Step 2

[0150] Add 500g of epoxy resin, organosilicon and solvent mixture to the reactor, introduce nitrogen gas as a protective gas, and heat to 118℃. Then, add the premixed solution obtained in step 1 to the reactor at a uniform rate over a period of 1.5 hours.

[0151] Step 3

[0152] After the addition was complete, the reaction was kept at a constant temperature for 0.5 hours. Then, 0.5 g of tert-butyl diethylhexanoate and 10 g of propylene glycol methyl ether were added to the reactor. After the addition was complete, the reaction was kept at a constant temperature for 4 hours. The temperature was then lowered to below 80°C, and 150 g of butyl acetate and 65 g of propylene glycol methyl ether were added to dilute the mixture, resulting in a modified acrylic resin with a solid content of 50.2%, a viscosity of 265 mPa•s, an acid value of 2.3 mgKOH / g, and an opaque appearance.

[0153] Third step: Preparation of high-temperature resistant and corrosion-resistant coatings

[0154] Step A. Preparation of black paste

[0155] 40g of modified acrylic resin, 2g of Disponer983 dispersant, 2g of xylene, 25g of copper chromate black, 15g of talc, 10g of glass powder, and 6g of zinc phosphate prepared by the above method were mixed evenly and ground until the average particle size was 18μm to obtain a black slurry.

[0156] Step B. Preparation of anti-corrosion coating

[0157] 35g of modified acrylic resin, 60g of black slurry, 0.3g of BYK310 wetting and leveling agent, 0.2g of BYK052 defoamer, and 4.2g of xylene were thoroughly mixed to prepare a high-temperature resistant anti-corrosion coating.

[0158] Comparative Example 2

[0159] This comparative example is based on Example 1, with the first step modified to prepare an organosilicon-epoxy resin, and the vinyltrimethoxysilane in step S2 of the first step removed, specifically:

[0160] First step: Preparation of organosilicon-epoxy resin

[0161] S1: Mix 150g of E-20 epoxy resin with 50g of methyl isobutyl ketone and 100g of xylene to form an epoxy resin mixture for later use.

[0162] S2: Mix 40g of methyltrimethoxysilane, 125g of phenyltrimethoxysilane, 50g of dimethyldiethoxysilane, 25g of diphenyldimethoxysilane and 20g of deionized water evenly and put them into the reaction vessel. Add 4.25g of 5.88% p-toluenesulfonic acid aqueous solution to the reaction vessel. After the exothermic reaction stops, continue heating to 66-68℃ and keep the reaction at this temperature for 3 hours.

[0163] S3: Add the epoxy resin mixture obtained in step S1 to the reactor, rinse the container and pipes with 40g xylene, stir evenly, add 10.10g of 0.99% dioctyltin dilaurate methyl isobutyl ketone solution, heat to 118℃ for 3 hours, and separate 105g of the alcohol generated in the reaction. After keeping warm for 3 hours, the coating is tested and found to be transparent, and an organosilicon-epoxy resin product with a solid content of 63.0% is obtained.

[0164] In the second step, an organosilicon-epoxy resin was used to replace the vinyl-containing organosilicon-epoxy resin in Example 1. The remaining steps and procedures were the same as in Example 1, resulting in a modified acrylic resin with a solid content of 49.25%, a viscosity of 209 mPa•s, an acid value of 2.1 mgKOH / g, and an opaque appearance.

[0165] Third step: Preparation of high-temperature resistant and corrosion-resistant coatings

[0166] Step A. Preparation of black paste

[0167] 40g of modified acrylic resin, 2g of Disponer983 dispersant, 2g of xylene, 25g of copper chromate black, 15g of talc, 10g of glass powder, and 6g of zinc phosphate prepared by the above method were mixed evenly and ground until the average particle size was 18μm to obtain a black slurry.

[0168] Step B. Preparation of anti-corrosion coating

[0169] 35g of modified acrylic resin, 60g of black slurry, 0.3g of BYK310 wetting and leveling agent, 0.2g of BYK052 defoamer, and 4.2g of xylene were thoroughly mixed to prepare a high-temperature resistant anti-corrosion coating.

[0170] The high-temperature resistant anti-corrosion coatings finally prepared through the above examples and comparative examples were diluted with solvent to the same solid content and then sprayed onto cold-rolled steel plates. The room temperature drying time, paint film appearance, paint film thickness, adhesion, impact resistance, hardness, neutral salt spray test, and temperature resistance test were measured respectively.

[0171] Among them, the room temperature drying time is recorded for the time required for surface drying, hard drying and complete hard drying; the appearance of the paint film is recorded for color uniformity and smoothness; the adhesion is determined according to the cross-cut adhesion test; the neutral salt spray test is tested for whether it passes after 240 hours; the heat resistance test is tested after 6 cycles of 300℃ for 2 hours, 400℃ for 2 hours and 500℃ for 2 hours, and the paint film state, the state after rapid cooling in cold water and the adhesion are observed respectively.

[0172] The recorded data is as follows:

[0173]

[0174] Based on the above measurement data, we can conclude that:

[0175] All embodiments exhibited excellent overall performance, especially in terms of adhesion, high temperature resistance, and salt spray resistance, which were significantly better than the comparative examples. This demonstrates that the modified acrylic resin preparation method effectively integrates the advantages of acrylic, epoxy, and silicone resins.

[0176] In Comparative Example 1, although a vinyl-containing silicone resin was prepared that could copolymerize with acrylic monomers, it was not grafted with epoxy resin. The low grafting rate between the epoxy resin and acrylic monomers resulted in poor compatibility. The coating exhibited uneven color, decreased adhesion and corrosion resistance, and the ungrafted silicone epoxy resin severely affected the coating's high-temperature resistance.

[0177] In Comparative Example 2, the use of vinyl-free silicone-epoxy resin resulted in poor resin compatibility, uneven color, reduced adhesion and corrosion resistance of the coating, and the use of ungrafted silicone acrylic resin also severely affected the high-temperature resistance of the coating.

[0178] The embodiments described above are not exhaustive and do not limit the invention to only certain specific embodiments. Clearly, many modifications and variations can be made based on the above description. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to effectively utilize the invention and its modifications. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A method for preparing a modified acrylic resin, characterized by, Includes the following steps: Step 1: Preparation of vinyl-containing organosilicon-epoxy resin S1: Stir and mix the epoxy resin with the first solvent to form an epoxy resin mixture; S2: Mix at least three of the following organosiloxane monomers (vinyltrimethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, dimethyldiethoxysilane, and diphenyldimethoxysilane) with deionized water at a mass ratio of 45-50:4-6 and add the mixture to a reaction vessel. Add an aqueous solution of at least one of hydrochloric acid, hydrofluoric acid, and p-toluenesulfonic acid at a mass percentage concentration of 1.0%-6.0% as a hydrolysis catalyst to the reaction vessel. The mass ratio of the hydrolysis catalyst to deionized water is 4-6:20-30. After the exothermic reaction stops, continue heating to 50-70°C and maintain the temperature for 2-5 hours. S3: Add the epoxy resin mixture obtained in step S1 to the reactor, stir evenly, add the grafted catalyst, heat to 100-150℃ for 2-4 hours, separate the alcohol generated by the reaction, keep warm for 2-3 hours, and obtain vinyl-containing organosilicon-epoxy resin. Second step: Preparation of modified acrylic resin Step 1: Mix styrene, acrylate monomer, initiator, and second solvent to form a premix; Step 2: Add the vinyl-containing silicone-epoxy resin obtained in the first step to the reactor, purge with nitrogen and heat to 100-150°C, then add the premixed liquid dropwise into the reactor at a uniform rate for 1-3 hours; Step 3: After the droplet addition is completed, keep the reaction at a constant temperature, add the initiator and solvent, and keep the reaction at 100-150℃ for 3-5 hours. Finally, cool down and add solvent to adjust the solid content to 49%-51%, the viscosity to 200-800 mPa·s, and the acid value to 2-5 mgKOH / g to obtain the modified acrylic resin.

2. The method for preparing the modified acrylic resin as described in claim 1, characterized in that, In step S1 of the first stage, the epoxy resin is at least one of E-44 epoxy resin, E-20 epoxy resin, and E-12 epoxy resin; the first solvent is at least two of xylene, propylene glycol methyl ether acetate, cyclohexanone, and methyl isobutyl ketone.

3. The method for preparing the modified acrylic resin as described in claim 1, characterized in that, In step 1 of the second stage, the acrylate monomer is selected from at least four of the following: butyl acrylate, butyl methacrylate, methyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, hydroxyethyl methacrylate phosphate, and acrylic acid.

4. The method for preparing the modified acrylic resin as described in claim 1, characterized in that, In step 1 of the second stage, the second solvent is at least one of butyl acetate, n-butanol, xylene, and propylene glycol methyl ether; the initiator is at least one of tert-butyl peroxide, tert-butyl perethylhexanoate, and di-tert-butyl peroxide.

5. Use of a modified acrylic resin prepared by the process according to any one of claims 1 to 4 for the production of a high temperature resistant anticorrosive coating, characterized in that, Includes the following steps: Step A. Preparation of slurry: Mix the modified acrylic resin, dispersant, diluent, pigments and fillers evenly, and grind until the fineness is ≤20μm to obtain the slurry; Step B. Preparation of coating: The modified acrylic resin, the slurry obtained in step A, the wetting and leveling agent, the defoamer, and the diluent are stirred and mixed evenly to prepare a high-temperature resistant anti-corrosion coating.

6. The application of the modified acrylic resin as described in claim 5 in the preparation of high-temperature resistant and corrosion-resistant coatings, characterized in that, In step A, the dispersant is Disponer 983, and the pigments and fillers include copper chromate black, talc, glass powder, and zinc phosphate.

7. The application of the modified acrylic resin as described in claim 5 in the preparation of high-temperature resistant and corrosion-resistant coatings, characterized in that, In step A, the mass ratio of the modified acrylic resin, dispersant, diluent, pigments and fillers is 30-50:1-5:1-5:40-70.

8. The application of the modified acrylic resin as described in claim 5 in the preparation of high-temperature resistant and corrosion-resistant coatings, characterized in that, In step B, the wetting and leveling agent is BYK310, and the defoamer is BYK052; The mass ratio of the modified acrylic resin, slurry, wetting and leveling agent, defoamer, and diluent is 20-40:50-80:0.3-1:0.1-0.5:5-10.

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