A low-gloss polyacrylate resin composition, and a method for preparing and using the same

Abstract

The present application relates to the technical field of chemical product processing, in particular to a low-gloss polyacrylate resin composition, a preparation method and application thereof, which comprises a modified polyacrylate resin solution, an epoxy-siloxane modifier, a vinyl trimethoxysilane oligomer, an organic metal catalyst, a viscosity regulator and a polymerization inhibitor; the ester bond in the modified polyacrylate resin is fixedly protected by the epoxy-siloxane modifier, and the ability of the epoxy-siloxane modifier is further enhanced by the vinyl trimethoxysilane oligomer, so that the problem that the gloss of the extinction type polyacrylate resin containing a bulky side group is irreversibly increased due to ester bond hydrolysis in a hot and humid environment is solved.

Description

Technical Field

[0001] This invention relates to the field of chemical product processing technology, specifically to a low-gloss polyacrylate resin composition, its preparation method, and its application. Background Technology

[0002] Low-gloss (or matte, matte) coatings have wide applications in many fields, including automotive interiors, high-end electronic product casings, home decoration, and industrial equipment, due to their advantages such as reducing light reflection, avoiding glare, and effectively masking minor defects in the substrate. To achieve a low-gloss effect, existing technologies introduce bulky side groups (such as cyclohexyl methacrylate) into the resin molecular chains of the raw materials. The large cyclohexyl side chains can increase the steric hindrance of the polymer chains, disrupting the regular arrangement and tight packing of the molecular chains during film formation. This results in a micro-scale non-uniform rough structure on the coating surface, causing strong diffuse reflection of incident light, which macroscopically manifests as low gloss.

[0003] However, the chemical bonds at the connection points between the aforementioned bulky side groups and the resin backbone are typically ester bonds (-COO-). Ester bonds are prone to hydrolysis and breakage under prolonged exposure to high temperature and humidity, causing the bulky cyclohexyl side chains, crucial for matting, to detach from the polymer network. The direct consequence is that the uneven, rough structure of the coating surface gradually becomes smoother due to localized backflow or rearrangement caused by increased polymer chain mobility. From a macroscopic performance perspective, this manifests as an irreversible increase in the coating's gloss over time. Summary of the Invention

[0004] (1) Technical problems to be solved

[0005] The purpose of this invention is to provide a low-gloss polyacrylate resin composition, its preparation method, and its application, in order to solve the problem that the gloss of matte polyacrylate resins containing large-volume side groups increases irreversibly due to ester bond hydrolysis under humid and hot conditions.

[0006] (2) Technical solution

[0007] To achieve the above objectives, in one aspect, the present invention provides a low-gloss polyacrylate resin composition comprising the following parts by weight: 200-210 parts of modified polyacrylate resin solution, 5-12 parts of epoxy-siloxane modifier, 3-10 parts of vinyltrimethoxysilane oligomer, 0.05-0.15 parts of organometallic catalyst, 0-25 parts of viscosity modifier, 0.01-0.05 parts of polymerization inhibitor, and 0.3-0.8 parts of free radical initiator;

[0008] The modified polyacrylate resin solution contains cyclohexyl methacrylate, which is a bulky cyclic ester monomer with ester bonds; the epoxy-siloxane modified material has epoxy and alkoxysilyl groups; and the vinyltrimethoxysilane oligomer is an oligomer with a degree of polymerization of 3-6, containing vinyl, silanol and alkoxy groups.

[0009] Furthermore, the organometallic catalyst includes dibutyltin dilaurate; the viscosity modifier is selected from propylene glycol methyl ether acetate or butyl acetate; the polymerization inhibitor is selected from p-hydroxyanisole or 2,6-di-tert-butyl-4-methylphenol; and the free radical initiator is selected from benzoyl peroxide or azobisisobutyronitrile.

[0010] Furthermore, the solid content of the modified polyacrylate resin solution is 48-52%.

[0011] Furthermore, the preparation method of the modified polyacrylate resin solution includes the following steps:

[0012] S11. Add propylene glycol methyl ether acetate to the reaction vessel, turn on nitrogen protection, turn on the stirring device, heat to a temperature of 140-145℃ and in a stable reflux state to obtain reaction solution A;

[0013] S12. In another container, cyclohexyl methacrylate, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, acrylic acid, n-dodecyl mercaptan, and propylene glycol methyl ether acetate are added sequentially and stirred until homogeneous. Then, di-tert-butyl peroxide is added and stirred until completely dissolved to obtain a monomer premix. Separately, di-tert-butyl peroxide is dissolved in propylene glycol methyl ether acetate to obtain a supplementary initiator solution.

[0014] S13. Add the monomer premixed liquid dropwise to reaction solution A, followed by the addition of initiator solution. After the addition is complete, continue the reaction, stop heating, and cool to 75-80℃ with continuous stirring. After filtration through a 200-mesh filter, collect the solution to obtain a modified polyacrylate resin solution.

[0015] Furthermore, the preparation method of the epoxy-siloxane modified material includes the following steps:

[0016] S21. In a reaction vessel, add hydrogen-terminated polydimethylsiloxane and p-hydroxyanisole, turn on nitrogen protection, turn on the stirring device, heat to 58-62℃, then add isopropanol solution of chloroplatinic acid, stir to disperse evenly, then add allyl glycidyl ether dropwise. After the addition is complete, control the temperature at 65-70℃ and continue stirring to obtain reaction solution B.

[0017] S22. Add vinyltrimethoxysilane dropwise to reaction solution B. After the addition is complete, continue stirring the reaction. After the reaction is complete, stop heating and cool to room temperature with continuous stirring. Filter and collect the product. Seal and package it under nitrogen protection to obtain epoxy-siloxane modified material.

[0018] Furthermore, the method for preparing the vinyltrimethoxysilane oligomer includes the following steps:

[0019] S31. In a reaction vessel, add vinyltrimethoxysilane, isopropanol and p-hydroxyanisole, turn on the stirrer, control the temperature at 25-30℃, add dropwise the acidified hydrolysate obtained by uniformly mixing deionized water and glacial acetic acid, after the dropwise addition is complete, raise the temperature to 35-40℃, and continue stirring the reaction to obtain reaction solution C.

[0020] S32. Raise the temperature of reaction solution C to 50-55℃ to initiate the condensation reaction. When the viscosity reaches the range of 15-25 mPa·s, terminate the reaction, distill under reduced pressure, cool to room temperature, add p-hydroxyanisole, stir to disperse it evenly, filter, and seal and package under nitrogen protection to obtain vinyltrimethoxysilane oligomer.

[0021] On the other hand, the present invention also provides a method for preparing a low-gloss polyacrylate resin composition, comprising the following steps:

[0022] S1. Premixing: The modified polyacrylate resin solution is continuously stirred at a speed of 200-400 r / min and a temperature of 25-30℃. Epoxy-siloxane modifier and vinyltrimethoxysilane oligomer are added sequentially and stirred for 20-30 min to ensure that the components are initially mixed evenly.

[0023] S2. Maturation: Slowly heat the mixture to 48-52℃, stir for 25-35 min, cool to 38-42℃, then add the organometallic catalyst and polymerization inhibitor, stir for 10-15 min to achieve uniform dispersion, and continue stirring for 120-240 min to carry out the maturation reaction;

[0024] S3. Viscosity Adjustment: After curing, stop heating and cool to room temperature with continuous stirring. Add viscosity adjuster to adjust viscosity, add free radical initiator, and stir at 30-35℃ for 5-10 minutes to achieve uniform dispersion. Take samples to test the product appearance, viscosity and solid content. After passing the test, filter through a 200-mesh filter, fill with nitrogen for protection, and seal in a light-proof container to obtain a low-gloss polyacrylate resin composition.

[0025] On the other hand, the present invention also provides an application of a low-gloss polyacrylate resin composition, which is used to prepare a low-gloss, high-weather-resistant coating; the specific form of the application is: dispersing and mixing the composition with pigments, fillers and additives to form a slurry, and then baking and curing it at 80-120℃ for 20-40 minutes.

[0026] In this invention, the modified polyacrylate resin utilizes the steric hindrance effect provided by cyclohexyl methacrylate to disrupt the orderly stacking of polymer chains, resulting in a pre-defined microscopically non-uniform surface in the cured film, thus providing an initial low gloss level for the coating. However, its ester bonds also become sites for hydrolysis reactions under humid and hot conditions.

[0027] In this invention, the epoxy groups at the end of the epoxy-siloxane modified material molecule undergo ring-opening reactions with carboxyl groups, hydroxyl groups, etc. in the resin, and are fixed around the ester bonds that need to be protected; the alkoxysilane groups of its side chain can be hydrolyzed and condensed under the action of ambient moisture to form a Si-O-Si cross-linked network. This network forms a barrier that prevents water molecules from penetrating through the hydrophobicity of the polysiloxane chain, and provides physical support for the surrounding resin chain segments, inhibiting the surface structure collapse and gloss recovery caused by local ester bond hydrolysis.

[0028] In this invention, the silanol and alkoxy groups of the vinyltrimethoxysilane oligomer further condense with the hydrolysis products of the epoxy-siloxane modified material, increasing the crosslinking density and compactness of the Si-O-Si network and enhancing the barrier and physical support capabilities formed by the epoxy-siloxane modified material. Simultaneously, the vinyl groups in the molecule undergo copolymerization with polyacrylate resin during the slurry curing process (initiated by heat or free radicals) to form C-C covalent bonds, anchoring the resin chains to the reinforced network and preventing phase separation.

[0029] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0030] 1. This invention achieves site-specific protection of ester bonds in modified polyacrylate resins by introducing epoxy-siloxane modified substances. The epoxy groups react with carboxyl and hydroxyl groups in the resin and are fixed around the ester bonds. The alkoxysilane groups of its side chains form a Si-O-Si cross-linking network, which blocks water molecule penetration and provides physical support for the surrounding resin segments, thus inhibiting the recovery of gloss.

[0031] 2. This invention further enhances the ability of epoxy-siloxane modified materials to protect ester bonds and inhibit gloss recovery by introducing vinyltrimethoxysilane oligomers. The silanol and alkoxy groups further condense with the hydrolysis products of epoxy-siloxane modified materials, increasing the crosslinking density and compactness of the Si-O-Si network and enhancing its barrier and physical support capabilities. At the same time, its vinyl groups undergo copolymerization with polyacrylate resin during the slurry curing process, anchoring the resin chains on the reinforced network and preventing phase separation. Attached Figure Description

[0032] Figure 1 This is a flowchart illustrating the preparation of a low-gloss polyacrylate resin composition according to Example 1 of the present invention.

[0033] Figure 2 This is a comparison image of the coatings obtained in Example 1 and Comparative Example 9 of the present invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1: This example discloses a low-gloss polyacrylate resin composition, comprising the following parts by weight: 200 parts modified polyacrylate resin solution, 8 parts epoxy-siloxane modifier, 6 parts vinyltrimethoxysilane oligomer, 0.10 parts organometallic catalyst, 8 parts viscosity modifier, 0.03 parts polymerization inhibitor, and 0.4 parts free radical initiator;

[0036] The modified polyacrylate resin solution contains cyclohexyl methacrylate, which is a bulky cyclic ester monomer with ester bonds; the epoxy-siloxane modified material has epoxy and alkoxysilyl groups; and the vinyltrimethoxysilane oligomer is an oligomer with a degree of polymerization of 3-6, containing vinyl, silanol and alkoxy groups.

[0037] The organometallic catalyst includes dibutyltin dilaurate; the viscosity modifier is selected from propylene glycol methyl ether acetate or butyl acetate; the polymerization inhibitor is selected from p-hydroxyanisole or 2,6-di-tert-butyl-4-methylphenol; and the free radical initiator is selected from benzoyl peroxide or azobisisobutyronitrile.

[0038] It should be noted that the polymerization inhibitors p-hydroxyanisole or 2,6-di-tert-butyl-4-methylphenol used in this invention are mainly used to inhibit the prepolymerization reaction initiated by trace amounts of free radicals during the storage of the composition, thus ensuring the storage stability of the product. During the curing stage of the slurry, due to the increase in curing temperature (80-120℃) or ultraviolet irradiation, the free radical initiator decomposes and generates a large number of active free radicals, the concentration of which far exceeds the inhibitory ability of the polymerization inhibitor. The polymerization inhibitor is rapidly consumed and does not affect the participation of vinyl groups in the copolymerization and crosslinking reaction.

[0039] The solid content of the modified polyacrylate resin solution is 48-52%.

[0040] The preparation method of the modified polyacrylate resin solution includes the following steps:

[0041] S11. In a 2000mL reaction vessel equipped with a mechanical stirrer, reflux condenser, temperature measuring device, inert gas inlet tube and dropping device, add 400g of propylene glycol methyl ether acetate, turn on nitrogen protection, control the gas flow rate at 80-120mL / min, and continuously ventilate for 10-20min to replace the air in the reaction system. Turn on the stirrer and heat to a temperature of 140-145℃ and a stable reflux state to obtain reaction solution A.

[0042] S12. In another clean container, add 350g cyclohexyl methacrylate, 300g methyl methacrylate, 280g butyl acrylate, 50g hydroxyethyl methacrylate, 20g acrylic acid, 8g n-dodecyl mercaptan, and 600g propylene glycol methyl ether acetate in sequence. After stirring and mixing evenly, add 8g di-tert-butyl peroxide and continue stirring until completely dissolved to obtain a monomer premix. Separately, dissolve 4g di-tert-butyl peroxide in 30g propylene glycol methyl ether acetate to obtain a supplementary initiator solution.

[0043] S13. The monomer premix is ​​added dropwise to reaction solution A at a constant rate using a dropping device. The dropping time is controlled at 2.5-3.5 h. During the dropping process, reflux is maintained, the reaction temperature is maintained at 140-145℃, and the stirring speed is maintained at 150-350 r / min. Then, the initiator solution is added dropwise over 20-40 min. After the dropping is completed, the reaction is continued at the temperature for 1.5-2.5 h. Heating is stopped, and the mixture is cooled to 75-80℃ under continuous stirring. After filtration through a 200-mesh filter, the modified polyacrylate resin solution is obtained.

[0044] It should be noted that if the solid content of the modified polyacrylate resin solution deviates from the target value, it can be adjusted by adding propylene glycol methyl ether acetate or by vacuum distillation at a temperature of 60-70℃ and a pressure of 10-20kPa, so that the final solid content is controlled within the range of 48% to 52%.

[0045] The preparation method of the epoxy-siloxane modified material includes the following steps:

[0046] S21. In a 1000mL reaction vessel equipped with a mechanical stirrer, reflux condenser, temperature measuring device, inert gas inlet tube, and dropping device, add 300g of hydrogen-terminated polydimethylsiloxane (hydrogen content 0.25-0.30wt%, number average molecular weight 1800-2200Da) and 0.05g of p-hydroxyanisole. Turn on nitrogen protection, control the gas flow rate at 30-80mL / min, and continue venting for 5-15min. Turn on the stirrer and set the rotation speed to 100-200rpm. Heat to 58-62℃ at 00r / min, then add 0.25g of isopropanol solution of chloroplatinic acid (platinum mass fraction of 1%), stir for 3-8min to disperse evenly, and then slowly add 65g of allyl glycidyl ether dropwise over 50-70min using a dropper. During the dropwise addition, control the reaction temperature to not exceed 70℃ by external cooling or adjusting the dropwise acceleration. After the dropwise addition is complete, control the temperature at 65-70℃ and continue stirring for 50-90min. After the reaction is complete, reaction solution B is obtained.

[0047] S22. Maintain the temperature of reaction solution B at 65-70℃, and slowly add 75g of vinyltrimethoxysilane dropwise over 30-60 minutes using a dropping device. After the addition is complete, continue stirring the reaction for 90-150 minutes. Confirm the characteristic absorption peak of the Si-H bond (approximately 2160 cm⁻¹) using infrared spectroscopy. -1 After the ions have mostly disappeared, the reaction is complete. Heating is stopped, and the mixture is cooled to room temperature (25-30℃) with continuous stirring. After filtration through a 200-mesh filter, the mixture is collected and sealed in a package under nitrogen protection to obtain the epoxy-siloxane modified material.

[0048] The method for preparing the vinyltrimethoxysilane oligomer includes the following steps:

[0049] S31. In a 500mL reaction vessel equipped with a mechanical stirrer, reflux condenser, temperature measuring device and dropping device, add 350g vinyltrimethoxysilane, 70g isopropanol and 0.035g p-hydroxyanisole. Turn on the stirrer and set the speed to 150-250r / min. Control the temperature at 25-30℃. Add the acidified hydrolysate obtained by mixing 31g deionized water and 1.75g ​​glacial acetic acid dropwise over 80-100min using the dropping device. After the dropwise addition is complete, slowly raise the temperature to 35-40℃ and continue stirring the reaction for 80-100min to obtain reaction solution C.

[0050] S32. Slowly raise the temperature of reaction solution C to 50-55℃, and allow the condensation reaction to proceed for 90-210 min. Take samples every 25-35 min to measure the viscosity at 25℃. When the viscosity reaches 15-25 mPa·s, immediately stop heating and start external cooling to lower the temperature to below 40℃, thus terminating the condensation reaction. Perform vacuum distillation at 40-45℃ and 10-20 kPa, cool to room temperature, add 0.03 g of p-hydroxyanisole, stir for 15-20 min to ensure uniform dispersion, then filter through a 200-mesh filter and seal under nitrogen protection to obtain vinyltrimethoxysilane oligomer.

[0051] The method for preparing a low-gloss polyacrylate resin composition includes the following steps:

[0052] S1. Premixing: The modified polyacrylate resin solution is continuously stirred at a speed of 200-400 r / min and a temperature of 25-30℃. Epoxy-siloxane modifier and vinyltrimethoxysilane oligomer are added sequentially and stirred for 20-30 min to ensure that the components are initially mixed evenly.

[0053] S2. Maturation: Slowly heat the mixture to 48-52℃ and stir for 25-35 minutes to remove trace amounts of moisture and promote further fusion of the components. Cool to 38-42℃, then add dibutyltin dilaurate (organometallic catalyst) and p-hydroxyanisole (polymerization inhibitor), stir for 10-15 minutes to ensure uniform dispersion, and continue stirring for 120-240 minutes for maturation reaction. During maturation, measure the viscosity of the system every 30-45 minutes. When the viscosity increases by 30% to 40% from the initial value, and the system appears uniform and transparent without layering or turbidity, maturation is complete.

[0054] It should be noted that if the viscosity increase does not reach 30% after 4 hours of curing, the curing time should be extended appropriately but not exceeding 6 hours; if the viscosity increase is too fast and exceeds 40%, curing should be stopped immediately and the next step should be initiated.

[0055] S3. Viscosity Adjustment: After curing, stop heating and cool to room temperature with continuous stirring. Add propylene glycol methyl ether acetate (viscosity adjuster) to adjust viscosity, then add benzoyl peroxide (free radical initiator). Stir at 30-35℃ for 5-10 minutes to achieve uniform dispersion. Sample and test the product's appearance, viscosity, and solid content. After passing the test, filter through a 200-mesh filter, fill with nitrogen for protection, and seal in a light-proof container to obtain a low-gloss polyacrylate resin composition. The preparation process is as follows: Figure 1 As shown.

[0056] The aforementioned low-gloss polyacrylate resin composition is used to prepare a low-gloss, high-weather-resistant coating. The specific form of the application is as follows: the composition is dispersed and mixed with pigments, fillers, and additives to form a slurry, which is then baked and cured at 80-120℃ for 20-40 minutes.

[0057] Example 2: This example is based on Example 1, but differs from Example 1 in that it includes the following components by weight: 200 parts of modified polyacrylate resin solution, 5 parts of epoxy-siloxane modifier, 3 parts of vinyltrimethoxysilane oligomer, 0.05 parts of organometallic catalyst, 0 parts of viscosity modifier, 0.01 parts of polymerization inhibitor, and 0.3 parts of free radical initiator.

[0058] The other components and preparation methods are the same as in Example 1.

[0059] Example 3: This example is based on Example 1, but differs from Example 1 in that it includes the following components by weight: 210 parts of modified polyacrylate resin solution, 12 parts of epoxy-siloxane modifier, 10 parts of vinyltrimethoxysilane oligomer, 0.15 parts of organometallic catalyst, 25 parts of viscosity modifier, 0.05 parts of polymerization inhibitor, and 0.8 parts of free radical initiator.

[0060] The other components and preparation methods are the same as in Example 1.

[0061] Example 4: This example is based on Example 1, but differs from Example 1 in that it includes the following components by weight: 205 parts of modified polyacrylate resin solution, 8 parts of epoxy-siloxane modifier, 6 parts of vinyltrimethoxysilane oligomer, 0.10 parts of organometallic catalyst, 12 parts of viscosity modifier, 0.03 parts of polymerization inhibitor, and 0.6 parts of free radical initiator.

[0062] The other components and preparation methods are the same as in Example 1.

[0063] Comparative Example 1: This comparative example is based on Example 1, but differs from Example 1 in that the epoxy-siloxane modified material in this comparative example is not grafted with epoxy groups (step S21 is not performed, and the hydrogen-terminated polydimethylsiloxane is directly subjected to hydrosilylation reaction with vinyltrimethoxysilane).

[0064] The other components and preparation methods are the same as in Example 1.

[0065] Comparative Example 2: This comparative example is based on Example 1, but differs from Example 1 in that the epoxy-siloxane modified material in this comparative example does not contain alkoxysilane groups (only step S21 is performed, and step S22 is not performed).

[0066] The other components and preparation methods are the same as in Example 1.

[0067] Comparative Example 3: This comparative example is based on Example 1, but differs from Example 1 in that it uses vinyltrimethoxysilane monomer instead of vinyltrimethoxysilane oligomer.

[0068] The other components and preparation methods are the same as in Example 1.

[0069] Comparative Example 4: This comparative example is based on Example 1, but differs from Example 1 in that the degree of polymerization of the vinyltrimethoxysilane oligomer in this comparative example is 1.5-2.5 (in step S32, the condensation reaction is terminated when the viscosity reaches the range of 5-10 mPa·s).

[0070] The other components and preparation methods are the same as in Example 1.

[0071] Comparative Example 5: This comparative example is based on Example 1, but differs from Example 1 in that the degree of polymerization of the vinyltrimethoxysilane oligomer in this comparative example is 10-15 (in step S32, the condensation reaction time is extended, and the reaction is terminated when the viscosity reaches the range of 80-120 mPa·s).

[0072] The other components and preparation methods are the same as in Example 1.

[0073] Comparative Example 6: This comparative example is based on Example 1, but unlike Example 1, it does not include epoxy-siloxane modified substances.

[0074] The other components and preparation methods are the same as in Example 1.

[0075] Comparative Example 7: This comparative example is based on Example 1, but differs from Example 1 in that it does not include vinyltrimethoxysilane oligomers.

[0076] The other components and preparation methods are the same as in Example 1.

[0077] Comparative Example 8: This comparative example is based on Example 1, but differs from Example 1 in that it does not include epoxy-siloxane modified materials and vinyltrimethoxysilane oligomers.

[0078] The other components and preparation methods are the same as in Example 1.

[0079] Comparative Example 9: This comparative example is a blank group, which only includes a single polyacrylate resin.

[0080] Experimental verification:

[0081] Experiment 1: Verify the effect of the composition in inhibiting the increase of gloss. The results are shown in Tables 1 and 2.

[0082] Test samples: The compositions obtained in Examples 1-4 and Comparative Examples 1-8 were added to a dispersion container. The stirring device was turned on, and the speed was set to 300-500 r / min. The dispersant and defoamer were added in sequence, and the mixture was stirred for 5 min to achieve uniform dispersion. Then, titanium dioxide was slowly added under continuous stirring. After stirring for 10 min, barium sulfate, talc, and fumed silica were added in sequence. The speed was increased to 800-1200 r / min, and high-speed dispersion was carried out for 30-40 min. During this period, the fineness of the pigment dispersion was checked every 10 min with a scraper fineness meter until the fineness reached below 20 μm. After dispersion, the speed was reduced to 300-500 r / min, leveling agent was added, and the mixture was stirred for 5 min to achieve uniform mixing. Propylene glycol methyl ether acetate was added to adjust the viscosity to 80-100 mPa·s (measured with a rotational viscometer at 25°C). Finally, the mixture was filtered through a 200-mesh filter to obtain the slurry. The coating was uniformly applied to a surface-treated tinplate (150mm × 70mm × 0.3mm) using air spraying, with the wet film thickness controlled between 80 and 100 μm. It was then cured in a 100℃ oven for 30 minutes and left at room temperature for 24 hours before testing. Comparative Example 9 used a single polyacrylate resin to prepare the coating using the same method.

[0083] Test method:

[0084] 1. Initial 60° gloss test: Performed according to GB / T 9754-2007 standard, using a BYK micro-TRI-gloss gloss meter, incident angle 60°, 5 test points are evenly selected on the surface of each sample (1 point at each of the four corners and the center), and the average value of the 5 points is taken as the gloss of the sample. 6 parallel samples are prepared for each group of samples.

[0085] 2. Damp heat aging test: Performed according to GB / T 1740-2007 standard. The test conditions are temperature 50±2℃ and relative humidity 95±3%. The samples were taken out after aging for 500h and 1000h respectively. After being placed at room temperature for 2h, the 60° gloss was measured and the gloss change rate was calculated. For each group of samples, 6 parallel samples were prepared for 500h aging test and 6 parallel samples were prepared for 1000h aging test.

[0086] 3. Adhesion test: Performed according to GB / T 9286-2021 standard, using a six-blade cross-cutting knife with a 1mm spacing and 3M adhesive. Test tape No. 610 was rated from 0 to 5: 0: The cut edges are completely smooth, with no coating peeling at the intersection of the cuts; 1: A small amount of coating peeling occurs at the intersection of the cuts, but the affected cross-cut area does not exceed 5%; 2: The coating peels off along the cut edges and / or at the cut intersections, with the affected cross-cut area greater than 5% but not more than 15%; 3: The coating peels off partially or completely along the cut edges in large fragments, and / or partially or completely peels off at different locations on the grid, with the affected cross-cut area greater than 15% but not more than 35%; 4: The coating peels off in large fragments along the cut edges, and / or some grids partially or completely peel off, with the affected cross-cut area greater than 35% but not more than 65%; 5: The coating peels off over a large area, with the affected cross-cut area greater than 65%. Initial adhesion was tested on 3 samples, and adhesion was tested on 3 samples after 1000 hours of aging.

[0087] 4. The pencil hardness test was performed in accordance with GB / T 6739-2006 standard, using Zhonghua brand high-grade drawing pencils and pencil hardness testers. The hardness grade was expressed as the hardest pencil that does not scratch the coating. Three samples were tested for initial hardness, and three samples were tested for hardness after aging for 1000 hours.

[0088] 5. Water resistance test shall be performed according to GB / T 1733-1993 standard. The sample shall be completely immersed in deionized water at 25±2℃ for 240h. After soaking, the sample shall be removed, the surface moisture shall be gently absorbed with filter paper, and the sample shall be left at room temperature for 2h. The appearance of the coating shall be visually observed (whether there is blistering, whitening, loss of gloss, peeling, etc.), and the 60° gloss shall be measured and the gloss change rate shall be calculated. Appearance evaluation criteria: no abnormality (no visible change in the appearance of the coating), slight whitening (the coating appears slightly white and hazy, which can be restored after drying), obvious whitening (the coating appears obviously white and cannot be completely restored after drying), slight blistering (a small number of bubbles with a diameter of less than 0.5mm appear on the surface of the coating), blistering (a large number of bubbles with a diameter of more than 0.5mm appear on the surface of the coating), edge peeling (peeling occurs at the edge of the coating). Six parallel samples shall be prepared for each group of samples.

[0089]

[0090]

[0091] According to the data in Tables 1 and 2, the combined action of epoxy-siloxane modifiers and vinyltrimethoxysilane oligomers can indeed effectively solve the problem of gloss recovery caused by ester bond hydrolysis in modified polyacrylate resins. All embodiments with complete formulations can maintain low gloss in humid and hot environments.

[0092] Compared with Comparative Example 9 (without cyclohexyl methacrylate with a large bulky side group), the coatings prepared from the Examples are matte white with visible granularity to the naked eye and have a low gloss; the coating prepared from Comparative Example 9 is bright white, smooth and flat on the surface, and has a high gloss; the physical comparison diagrams of the coatings prepared from Example 1 and Comparative Example 9 are as Figure 2 shown.

[0093] Experiment 2: Verify the basic properties of the composition. The results are shown in Table 3.

[0094] Test samples: Examples 1-4. Three parallel samples were prepared for each group of samples.

[0095] Test methods:

[0096] 1. Appearance test: Take about 50 mL of the composition sample and place it in a 100 mL transparent glass bottle. Observe visually under natural light or standard light source (D65), and record the color, transparency, uniformity of the sample, and any abnormal phenomena such as gel, precipitation, delamination, mechanical impurities, etc.

[0097] 2. Solids content test: Perform according to the standard of GB / T 1725-2007. Accurately weigh about 2 g of the composition sample into an already constant-weight aluminum foil dish, place it in a forced-air drying oven at 105±2°C for baking for 2 h, take it out and place it in a desiccator to cool for 30 min, and weigh the mass of the residue. The formula for calculating the solids content is: Solids content (%) = (mass after baking ÷ mass before baking) × 100%.

[0098] 3. Viscosity test: Perform according to the standard of GB / T 9751.1-2008. Use a rotational viscometer, control the temperature at 25±0.5°C, and record the viscosity value after the reading is stable.

[0099] 4. Storage stability test: Seal the composition sample in a brown glass bottle, place it under the condition of accelerated aging storage at 50±2°C for 14 days, detect the appearance and viscosity of the sample, and calculate the viscosity change rate. The formula for calculating the viscosity change rate is: Viscosity change rate (%) = (viscosity after storage - initial viscosity) ÷ initial viscosity × 100%. The judgment criterion is: no gel, no precipitation, no delamination in appearance, and the absolute value of the viscosity change rate does not exceed 15% is qualified.

[0100]

[0101] The above are only the preferred embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent substitutions, and improvements made by any person skilled in the art within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A low-gloss polyacrylate resin composition, characterized in that, The composition includes the following components by weight: 200-210 parts of modified polyacrylate resin solution, 5-12 parts of epoxy-siloxane modifier, 3-10 parts of vinyltrimethoxysilane oligomer, 0.05-0.15 parts of organometallic catalyst, 0-25 parts of viscosity modifier, 0.01-0.05 parts of polymerization inhibitor, and 0.3-0.8 parts of free radical initiator; The modified polyacrylate resin solution contains cyclohexyl methacrylate, which is a bulky cyclic ester monomer with ester bonds; the epoxy-siloxane modified material has epoxy and alkoxysilyl groups; and the vinyltrimethoxysilane oligomer is an oligomer with a degree of polymerization of 3-6, containing vinyl, silanol and alkoxy groups.

2. The low-gloss polyacrylate resin composition according to claim 1, characterized in that, The organometallic catalyst includes dibutyltin dilaurate; the viscosity modifier is selected from propylene glycol methyl ether acetate or butyl acetate; the polymerization inhibitor is selected from p-hydroxyanisole or 2,6-di-tert-butyl-4-methylphenol; and the free radical initiator is selected from benzoyl peroxide or azobisisobutyronitrile.

3. The low-gloss polyacrylate resin composition according to claim 1, characterized in that, The solid content of the modified polyacrylate resin solution is 48-52%.

4. The low-gloss polyacrylate resin composition according to claim 1, characterized in that, The preparation method of the modified polyacrylate resin solution includes the following steps: S11. Add propylene glycol methyl ether acetate to the reaction vessel, turn on nitrogen protection, turn on the stirring device, heat to a temperature of 140-145℃ and in a stable reflux state to obtain reaction solution A; S12. In another container, cyclohexyl methacrylate, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, acrylic acid, n-dodecyl mercaptan, and propylene glycol methyl ether acetate are added sequentially and stirred until homogeneous. Then, di-tert-butyl peroxide is added and stirred until completely dissolved to obtain a monomer premix. Separately, di-tert-butyl peroxide is dissolved in propylene glycol methyl ether acetate to obtain a supplementary initiator solution. S13. Add the monomer premixed liquid dropwise to reaction solution A, followed by the addition of initiator solution. After the addition is complete, continue the reaction, stop heating, and cool to 75-80℃ with continuous stirring. After filtration through a 200-mesh filter, collect the solution to obtain a modified polyacrylate resin solution.

5. The low-gloss polyacrylate resin composition according to claim 1, characterized in that, The preparation method of the epoxy-siloxane modified material includes the following steps: S21. In a reaction vessel, add hydrogen-terminated polydimethylsiloxane and p-hydroxyanisole, turn on nitrogen protection, turn on the stirring device, heat to 58-62℃, then add isopropanol solution of chloroplatinic acid, stir to disperse evenly, then add allyl glycidyl ether dropwise. After the addition is complete, control the temperature at 65-70℃ and continue stirring to obtain reaction solution B. S22. Add vinyltrimethoxysilane dropwise to reaction solution B. After the addition is complete, continue stirring the reaction. After the reaction is complete, stop heating and cool to room temperature with continuous stirring. Filter and collect the product. Seal and package it under nitrogen protection to obtain epoxy-siloxane modified material.

6. The low-gloss polyacrylate resin composition according to claim 1, characterized in that, The method for preparing the vinyltrimethoxysilane oligomer includes the following steps: S31. In a reaction vessel, add vinyltrimethoxysilane, isopropanol and p-hydroxyanisole, turn on the stirrer, control the temperature at 25-30℃, add dropwise the acidified hydrolysate obtained by uniformly mixing deionized water and glacial acetic acid, after the dropwise addition is complete, raise the temperature to 35-40℃, and continue stirring the reaction to obtain reaction solution C. S32. Raise the temperature of reaction solution C to 50-55℃ to initiate the condensation reaction. When the viscosity reaches the range of 15-25 mPa·s, terminate the reaction, distill under reduced pressure, cool to room temperature, add p-hydroxyanisole, stir to disperse it evenly, filter, and seal and package under nitrogen protection to obtain vinyltrimethoxysilane oligomer.

7. A method for preparing a low-gloss polyacrylate resin composition according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Premixing: The modified polyacrylate resin solution is continuously stirred at a speed of 200-400 r / min and a temperature of 25-30℃. Epoxy-siloxane modifier and vinyltrimethoxysilane oligomer are added sequentially and stirred for 20-30 min to ensure that the components are initially mixed evenly. S2. Maturation: Slowly heat the mixture to 48-52℃, stir for 25-35 min, cool to 38-42℃, then add the organometallic catalyst and polymerization inhibitor, stir for 10-15 min to achieve uniform dispersion, and continue stirring for 120-240 min to carry out the maturation reaction; S3. Viscosity Adjustment: After curing, stop heating and cool to room temperature with continuous stirring. Add viscosity adjuster to adjust viscosity, add free radical initiator, and stir at 30-35℃ for 5-10 minutes to achieve uniform dispersion. Take samples to test the product appearance, viscosity and solid content. After passing the test, filter through a 200-mesh filter, fill with nitrogen for protection, and seal in a light-proof container to obtain a low-gloss polyacrylate resin composition.

8. The application of a low-gloss polyacrylate resin composition according to any one of claims 1-6, characterized in that, The composition is used to prepare a coating with low gloss and high weather resistance. The specific form of the application is as follows: the composition is dispersed and mixed with pigments, fillers and additives to form a slurry, and then baked and cured at 80-120℃ for 20-40 minutes.

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