Acrylic resin composition with low VOC (volatile organic compound) emission as well as preparation method and application of acrylic resin composition

Abstract

The invention belongs to the technical field of acrylic resin manufacturing, and discloses an acrylic resin composition with low VOC emission as well as a preparation method and application thereof. Acrylic acid and glycidyl tertiary carboxylic ester are pre-polymerized firstly, then a monomer mixture II is added for polymerization to prepare water-based acrylic resin, and acrylamide in the monomer mixture II reduces VOC emission in the acrylic resin composition through chemical adsorption; barium-doped modified zinc stannate is formed on the surface of graphene oxide through a hydrothermal reaction of sulfur-doped graphene oxide, zinc acetate dihydrate, tin chloride pentahydrate and barium chloride, the nano VOC inhibitor is prepared through high-temperature calcination, and electron transfer can be promoted through compounding of graphene and zinc stannate so as to improve the VOC catalytic degradation efficiency. The acrylic resin composition with low VOC emission prepared by the invention has excellent scratch resistance and low VOC emission performance.

Description

Technical Field

[0001] This invention belongs to the field of acrylic resin manufacturing technology, specifically relating to low-VOC emission acrylic resin compositions, their preparation methods, and applications. Background Technology

[0002] Volatile organic compounds (VOCs) are organic compounds with a saturated vapor pressure exceeding 100 Pa at room temperature. They mainly include benzene compounds, aromatic hydrocarbons, halogenated hydrocarbons, alcohols, and aldehydes. Traditional acrylic resins often use aromatic compounds as solvents, and the gaseous pollutants generated during production are primarily VOCs, significantly impacting the production environment and posing a threat to human health. With increasing public awareness of environmental protection, VOC emissions are facing increasingly stringent restrictions. Waterborne acrylic resins, as an environmentally friendly material with low VOC content, are widely used in waterborne coatings and inks. However, shortcomings such as high viscosity, insufficient adhesion, and low film hardness remain unresolved.

[0003] Chinese invention patent CN115403716B discloses a UV-curable acrylic resin composition and its preparation and application. This composition involves mixing oligomer A (with a siloxane alkyl group at one end and an acrylate double bond at the other) with a low-viscosity, low-modulus fluorinated acrylate polymer (oligomer B). This effectively improves the adhesion of the system to the matrix and solves the common incompatibility problem between conventional silane coupling agents and low-refractive-index fluorinated acrylates. The oligomers in this invention are synthesized under mild conditions, requiring no solvents, producing no byproducts, avoiding raw material waste, saving resources, and simplifying post-processing without generating waste, making it safe and environmentally friendly. Furthermore, the oligomers exhibit good compatibility and similar refractive indices, allowing the fluorinated acrylate composition to possess numerous advantages such as high performance, high transparency, and low refractive index. However, existing technologies lack the technical challenge of further improving acrylic resin additives to reduce VOC content and expand its application range in metal protective coatings. Summary of the Invention

[0004] The purpose of this invention is to provide a low-VOC emission acrylic resin composition, its preparation method, and its application, in order to solve the technical problem in the prior art that the VOC content in acrylic resin has not been reduced and its application range in metal protective coatings has not been expanded through further improvements to acrylic resin additives.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A low-VOC emission acrylic resin composition is prepared from the following components in parts by weight: 85-95 parts waterborne acrylic resin, 0.5-2 parts nano-VOC inhibitor, 0.5-3 parts leveling agent, 0.5-3 parts defoamer and 0.5-2 parts ultraviolet absorber; The waterborne acrylic resin is prepared from the following components in parts by weight: 15-20 parts of monomer mixture one, 85-100 parts of monomer mixture two, 5-10 parts of triethylamine and 90-160 parts of deionized water; The monomer mixture comprises the following raw materials in parts by weight: 4-6 parts acrylic acid, 0.8-1.2 parts 1,1-stilbene and 12-15 parts glycidyl tert-carbonate; The monomer mixture two comprises the following raw materials in parts by weight: 20-30 parts hydroxyethyl methacrylate, 12-18 parts acrylic acid, 18-25 parts methyl acrylate, 16-20 parts butyl acrylate, 3-5 parts diethylaminoethyl methacrylate, 3-5 parts acrylamide, 2-4 parts 1,1-stilbene, and 1-5 parts scratch-resistant additives.

[0006] The ultraviolet absorber is any one of UV-9, UV-3030, and UV-531; The preparation method of the nano-VOC inhibitor includes the following steps: S11. Add graphene oxide to deionized water to obtain a graphene oxide mixture, add thioacetamide and stir evenly, heat to hydrothermal reaction, filter to collect solid, wash and dry to obtain sulfur-doped graphene. S12. Sulfur-doped graphene was dispersed in ethanol to obtain a sulfur-doped graphene dispersion. The sulfur-doped graphene dispersion, zinc acetate dihydrate and tin chloride pentahydrate were added to deionized water. Sodium hydroxide solution was added to adjust the pH. Barium chloride was added, and the mixture was heated for hydrothermal reaction. The solid obtained was filtered and washed. The solid was washed and dried. The graphene was calcined at high temperature in a nitrogen atmosphere to reduce it and obtain a nano-VOC inhibitor.

[0007] Preferably, in S11, the concentration of graphene oxide in deionized water is 6-10 mg / mL, the mass ratio of graphene oxide to thioacetamide is 12-18:7-8, the reaction is carried out at a high temperature of 170-180℃ for 10-12 h, washed with ethanol, and dried at 60-80℃.

[0008] Preferably, the mass ratio of sulfur-doped graphene, zinc acetate, tin chloride, and barium chloride in S12 is 1~1.1:4.4:3.5:0.08~0.1. Sodium hydroxide solution is added to adjust the pH to 7~7.5, the temperature is raised to 160~180℃ and reacted for 20~24h, and then calcined at 750~850℃ for 1~2h.

[0009] The method for preparing the scratch-resistant additive includes the following steps: S21. Microcrystalline cellulose was added to a mixed solution of 37% hydrochloric acid and acrylic acid for acid hydrolysis. The reaction was heated, centrifuged and filtered to collect the supernatant. Sodium bicarbonate was added to adjust the pH and precipitate impurities. The supernatant was collected again by centrifugation and filtration and dialyzed to obtain grafted nanocellulose. S22. 5-Methoxy-2-methylindole, triethylamine and toluene were added to a reaction vessel and stirred to dissolve. Methacryl chloride was added under ice bath conditions, and the reaction was heated. Solid impurities were removed by filtration, and toluene was removed by rotary evaporation to obtain a scratch-resistant monomer. S23. Grafted nanocellulose, scratch-resistant monomer and diethylene glycol butyl ether are added to a reaction vessel, azobisisobutyronitrile is added, and the mixture is heated to react and obtain a scratch-resistant additive.

[0010] The reaction principle of the scratch-resistant monomer is as follows:

[0011] The mass spectrometry analysis results of the above scratch-resistant monomers are as follows: m / z: 229.11 (100.0%), 230.11 (15.6%), 231.12 (1.1%).

[0012] Preferably, in S21, the volume ratio of 37% hydrochloric acid to acrylic acid is 1:2, the amount of microcrystalline cellulose added is 1-2% of the mass of the mixed solution of hydrochloric acid and acrylic acid, acid hydrolysis is performed at room temperature for 10-12 hours, the temperature is raised to 95-100℃ for 4-6 hours, centrifugation and filtration are performed at 6000-8000 rpm, sodium bicarbonate is added dropwise to adjust the pH to 5-5.5, and the dialysis molecular cutoff is 8-15 KD.

[0013] Preferably, the ratio of 5-methoxy-2-methylindole, methacryloyl chloride, triethylamine and toluene in S22 is (16~18) g: (10~12) g: (10~11) mL: (70~100) mL, and the reaction is carried out at room temperature for 20~24 h.

[0014] Preferably, the ratio of grafted nanocellulose, scratch-resistant monomer, diethylene glycol butyl ether and azobisisobutyronitrile in S23 is (1~3) g: (12~15) g: (50~60) mL: (0.1~0.3) g, and the reaction is carried out at 80~90℃ for 4~6 h.

[0015] The preparation method of the waterborne acrylic resin includes the following steps: S31. Add a high-boiling-point solvent to a reaction vessel, add monomer mixture I and tetrabutylammonium bromide catalyst under a nitrogen atmosphere, stir, keep the reaction at a constant temperature, and dry by rotary evaporation to obtain a viscosity-reducing precursor. S32. The viscosity-reducing precursor, monomer mixture II, high-boiling-point solvent and azobisisobutyronitrile are added to a reaction vessel and heated to reflux. The reaction is carried out under pressure and temperature in a nitrogen atmosphere. Triethylamine is added for neutralization. Deionized water is added and stirred at high speed to obtain an aqueous acrylic resin.

[0016] Preferably, the high-boiling-point solvent in S31 and S32 is any one of diethylene glycol butyl ether, diethylene glycol ethyl ether, and propylene glycol methyl ether. Preferably, the amount of tetrabutylammonium bromide catalyst added in S31 is 1-3% of the mass of the monomer mixture, and the reaction is carried out at 150-160°C for 4-6 hours.

[0017] Preferably, the amount of azobisisobutyronitrile added in S32 is 1-3% of the mass of the monomer mixture, and the reaction is carried out at 140-150℃ for 1-2 hours. Deionized water is then added and the mixture is stirred at high speed at 4000-5000 rpm for 10-20 minutes.

[0018] A method for preparing a low-VOC-emission acrylic resin composition involves stirring an aqueous acrylic resin, a defoamer, and a leveling agent at 300-400 rpm for 1-2 minutes, adding a nano-VOC inhibitor, stirring at 400-600 rpm for 3-5 minutes, and then filtering and degassing through a 200-300 mesh sieve to obtain the low-VOC-emission acrylic resin composition.

[0019] Application of low-VOC-emission acrylic resin compositions in the preparation of protective coatings for metals.

[0020] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention involves using sulfur-doped graphene oxide, followed by a hydrothermal reaction of zinc acetate dihydrate, tin chloride pentahydrate, and barium chloride to form barium-doped modified zinc stannate on the graphene oxide surface. The graphene oxide is then reduced by high-temperature calcination to obtain nano-VOC inhibitors. Sulfur-doped graphene oxide increases the number of chemically active sites on the graphene oxide surface, guiding the uniform growth of barium-doped modified zinc stannate on its surface and preventing aggregation. Zinc stannate exhibits excellent sensitivity to VOCs, and the formation of oxygen vacancies by the barium-doped modified zinc stannate improves the adsorption and catalytic degradation efficiency of VOCs. The graphene-zinc stannate composite forms a heterojunction that enhances the conductivity of the nano-VOC inhibitor, promoting electron transfer between the nano-VOC inhibitor and gas molecules to improve the catalytic degradation efficiency of VOCs. Furthermore, zinc stannate possesses flame-retardant and smoke-suppressing properties, improving the flame-retardant properties of acrylic resin compositions.

[0021] 2. This invention involves the hydrolysis of microcrystalline cellulose with hydrochloric acid to form nano-sized cellulose, followed by grafting with acrylic acid to form grafted nanocellulose. 5-Methoxy-2-methylindole reacts with methacryloyl chloride to graft double bonds, which are then polymerized with the grafted nanocellulose to obtain a scratch-resistant additive. The grafted nanocellulose, acting as a nano-reinforcing agent, can be uniformly dispersed in acrylic resin, preventing microcrack propagation by transferring and dispersing stress. The introduction of a rigid indole ring by 5-methoxy-2-methylindole improves the scratch resistance of the acrylic resin composition. The polymerized scratch-resistant additive copolymerizes with monomers such as acrylic acid and methacrylate through double bonds, preventing the decline in scratch resistance caused by migration.

[0022] 3. In this invention, acrylic acid and glycidyl tert-carbonate are first prepolymerized, and glycidyl tert-carbonate is first ring-opened and grafted with acrylic acid to increase the steric hindrance during the polymerization of acrylic resin. 1,1-stilbene is added as a polymerization inhibitor to reduce the molecular weight and viscosity of acrylic resin, thereby reducing the amount of organic solvent added and reducing the VOC content in acrylic resin. In monomer mixture two, VOC emissions in acrylic resin composition are reduced by the chemical adsorption of VOCs by amide groups, and the adhesion of waterborne acrylic resin is improved by the adsorption force of ethylamine groups on metals. The waterborne acrylic resin prepared by adjusting the ratio of hydroxyethyl methacrylate, acrylic acid, methyl acrylate and butyl acrylate has excellent weather resistance and scratch resistance. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0024] The leveling agent involved in this invention is BYK-358, the defoamer is BYK-024, and the microcrystalline cellulose is KG-802 with an average particle size of 50μm.

[0025] Example 1: The low-VOC emission acrylic resin composition of this example is prepared from the following components: 90g of waterborne acrylic resin, 0.5g of nano-VOC inhibitor, 1.5g of leveling agent, 0.5g of defoamer and 1.5g of ultraviolet absorber. The monomer mixture comprises the following raw materials: 4g of acrylic acid, 0.8g of 1,1-stilbene and 12g of glycidyl tert-carbonate; The monomer mixture two comprises the following raw materials in parts by weight: 20g of hydroxyethyl methacrylate, 18g of acrylic acid, 21g of methyl acrylate, 18g of butyl acrylate, 3g of diethylaminoethyl methacrylate, 3g of acrylamide, 2g of 1,1-stilbene and 1g of scratch-resistant additive. The waterborne acrylic resin is obtained by mixing monomer mixture one and monomer mixture two prepared above with 9g of triethylamine and 90g of deionized water; The ultraviolet absorber is UV-9; The preparation method of the nano-VOC inhibitor in this embodiment includes the following steps: S11. Add 0.6g of graphene oxide to 100mL of deionized water to obtain a graphene oxide mixture. Add 0.35g of thioacetamide and stir evenly. React at 170℃ for 12h using hydrothermal reaction. Filter to collect the solid, wash with ethanol, and dry at 80℃ to obtain sulfur-doped graphene. S12. 1g of sulfur-doped graphene was dispersed in 50mL of ethanol to obtain a sulfur-doped graphene dispersion. 50mL of the sulfur-doped graphene dispersion, 4.4g of zinc acetate dihydrate and 3.5g of tin chloride pentahydrate were added to 50mL of deionized water. Sodium hydroxide solution was added to adjust the pH to 7. 0.08g of barium chloride was added, and the mixture was heated to 180℃ and reacted for 20h. The resulting solid was filtered, washed, dried, and then calcined at 800℃ for 2h in a nitrogen atmosphere to reduce the graphene, thus obtaining a nano-VOC inhibitor.

[0026] The preparation method of the scratch-resistant additive in this embodiment includes the following steps: S21. Add 3g of microcrystalline cellulose to 120mL of a mixed solution prepared by mixing 37% hydrochloric acid and acrylic acid in a volume ratio of 1:2. Acid hydrolysis was carried out at room temperature for 10h, followed by heating to 95℃ and reacting for 4h. The supernatant was collected by centrifugation and filtration at 6000rpm. Sodium bicarbonate was added to adjust the pH to 5 to precipitate impurities. The supernatant was collected by centrifugation and filtration again at 6000rpm. Dialysis was performed with a molecular cutoff of 8KD to obtain grafted nanocellulose. S22. 16.6 g of 5-methoxy-2-methylindole, 11 mL of triethylamine and 100 mL of toluene were added to a reaction vessel and stirred to dissolve. 10 g of methacryloyl chloride was added under ice bath conditions. The mixture was heated to room temperature and reacted for 24 h. Solid impurities were removed by filtration and toluene was removed by rotary evaporation to obtain a scratch-resistant monomer. S23. Add 3g of grafted nanocellulose, 12g of scratch-resistant monomer and 50mL of diethylene glycol butyl ether to a reaction vessel, add 0.1g of azobisisobutyronitrile, heat to 80℃ and react for 4h to obtain a scratch-resistant additive.

[0027] The preparation method of the waterborne acrylic resin in this embodiment includes the following steps: S31. Add 100 mL of diethylene glycol butyl ether to the reactor, add monomer mixture one and tetrabutylammonium bromide catalyst under nitrogen atmosphere and stir. The amount of tetrabutylammonium bromide catalyst added is 1% of the mass of monomer mixture one. Keep the reaction at 160℃ for 6 h and dry by rotary evaporation to obtain the viscosity-reducing precursor. S32. The viscosity-reducing precursor, monomer mixture II, 150 mL of diethylene glycol butyl ether and azobisisobutyronitrile were added to a reaction vessel and heated to reflux. The amount of azobisisobutyronitrile added was 1% of the mass of monomer mixture II. The reaction was carried out under nitrogen atmosphere and pressurized to 140°C for 2 h. Triethylamine was added for neutralization, and deionized water was added. The mixture was stirred at high speed of 4000 rpm for 10 min to obtain waterborne acrylic resin.

[0028] The method for preparing the low-VOC emission acrylic resin composition in this embodiment involves stirring an aqueous acrylic resin, a defoamer, and a leveling agent at 300 rpm for 1 min, adding a nano-VOC inhibitor, stirring at 600 rpm for 5 min, and then filtering and defoaming through a 200-mesh sieve to obtain the low-VOC emission acrylic resin composition.

[0029] The application of the low-VOC-emission acrylic resin composition in this embodiment is for use in metal protective coatings.

[0030] Example 2: The low-VOC emission acrylic resin composition of this example is prepared from the following components: 85g of waterborne acrylic resin, 1g of nano-VOC inhibitor, 0.6g of leveling agent, 0.6g of defoamer and 0.5g of ultraviolet absorber. The monomer mixture comprises the following raw materials: 5g of acrylic acid, 1g of 1,1-stilbene and 14g of glycidyl tert-carbonate. The monomer mixture two comprises the following raw materials in parts by weight: 30g of hydroxyethyl methacrylate, 15g of acrylic acid, 22g of methyl acrylate, 17g of butyl acrylate, 4g of diethylaminoethyl methacrylate, 4g of acrylamide, 3g of 1,1-stilbene and 3g of scratch-resistant additive. The waterborne acrylic resin is obtained by mixing monomer mixture one and monomer mixture two prepared above with 5g of triethylamine and 120g of deionized water; The ultraviolet absorber is UV-3030; The preparation method of the nano-VOC inhibitor in this embodiment includes the following steps: S11. Add 0.9g of graphene oxide to 100mL of deionized water to obtain a graphene oxide mixture. Add 0.4g of thioacetamide and stir evenly. React at 180℃ for 12h using hydrothermal reaction. Filter to collect the solid, wash with ethanol, and dry at 60℃ to obtain sulfur-doped graphene. S12. 1g of sulfur-doped graphene was dispersed in 60mL of ethanol to prepare a sulfur-doped graphene dispersion. 60mL of the sulfur-doped graphene dispersion, 4.4g of zinc acetate dihydrate and 3.5g of tin chloride pentahydrate were added to 60mL of deionized water. Sodium hydroxide solution was added to adjust the pH to 7. 0.09g of barium chloride was added, and the mixture was heated to 170℃ and reacted for 22h. The resulting solid was filtered, washed, dried, and then calcined at 770℃ for 2h in a nitrogen atmosphere to reduce the graphene, thus obtaining a nano-VOC inhibitor.

[0031] The preparation method of the scratch-resistant additive in this embodiment includes the following steps: S21. Add 2g of microcrystalline cellulose to 100mL of a mixed solution prepared by mixing 37% hydrochloric acid and acrylic acid in a volume ratio of 1:2. Acid hydrolysis was carried out at room temperature for 12h, followed by heating to 100℃ and reacting for 6h. The supernatant was collected by centrifugation and filtration at 7000rpm. Sodium bicarbonate was added to adjust the pH to 5.2 to precipitate impurities. The supernatant was collected by centrifugation and filtration again at 7000rpm. Dialysis was performed with a molecular cutoff of 10KD to obtain grafted nanocellulose. S22. 17g of 5-methoxy-2-methylindole, 11mL of triethylamine and 80mL of toluene were added to a reaction vessel and stirred to dissolve. 12g of methacryloyl chloride was added under ice bath conditions. The mixture was heated to room temperature and reacted for 20h. Solid impurities were removed by filtration and toluene was removed by rotary evaporation to obtain a scratch-resistant monomer. S23. Add 1g of grafted nanocellulose, 12g of scratch-resistant monomer and 60mL of diethylene glycol butyl ether to a reaction vessel, add 0.2g of azobisisobutyronitrile, heat to 80℃ and react for 5h to obtain a scratch-resistant additive.

[0032] The preparation method of the waterborne acrylic resin in this embodiment includes the following steps: S31. Add 100 mL of diethylene glycol ethyl ether to the reaction vessel, add monomer mixture one and tetrabutylammonium bromide catalyst under a nitrogen atmosphere and stir. The amount of tetrabutylammonium bromide catalyst added is 2% of the mass of monomer mixture one. Keep the reaction at 155℃ for 5 h and dry by rotary evaporation to obtain the viscosity-reducing precursor. S32. The viscosity-reducing precursor, monomer mixture II, 150 mL of diethylene glycol ethyl ether and azobisisobutyronitrile were added to a reaction vessel and heated to reflux. The amount of azobisisobutyronitrile added was 2.5% of the mass of monomer mixture II. The reaction was carried out under nitrogen atmosphere and pressurized to 150°C for 1.5 h. Triethylamine was added for neutralization, and deionized water was added. The mixture was stirred at high speed of 4500 rpm for 15 min to obtain waterborne acrylic resin.

[0033] The method for preparing the low-VOC emission acrylic resin composition in this embodiment involves stirring an aqueous acrylic resin, a defoamer, and a leveling agent at 350 rpm for 1 min, adding a nano-VOC inhibitor, stirring at 500 rpm for 4 min, and then filtering and degassing through a 300-mesh sieve to obtain the low-VOC emission acrylic resin composition.

[0034] The application of the low-VOC-emission acrylic resin composition in this embodiment is for use in metal protective coatings.

[0035] Example 3: The low-VOC emission acrylic resin composition of this example is prepared from the following components: 95g of waterborne acrylic resin, 1.5g of nano-VOC inhibitor, 2.5g of leveling agent, 1.5g of defoamer and 2g of ultraviolet absorber. The monomer mixture comprises the following raw materials: 6g of acrylic acid, 1.2g of 1,1-stilbene and 12g of glycidyl tert-carbonate; The monomer mixture two comprises the following raw materials in parts by weight: 25g of hydroxyethyl methacrylate, 12g of acrylic acid, 25g of methyl acrylate, 16g of butyl acrylate, 5g of diethylaminoethyl methacrylate, 5g of acrylamide, 4g of 1,1-stilbene and 5g of scratch-resistant additive.

[0036] The waterborne acrylic resin is obtained by mixing monomer mixture one and monomer mixture two prepared above with 10g of triethylamine and 140g of deionized water; The ultraviolet absorber is UV-531; The preparation method of the nano-VOC inhibitor in this embodiment includes the following steps: S11. Add 0.8g of graphene oxide to 100mL of deionized water to obtain a graphene oxide mixture. Add 0.4g of thioacetamide and stir evenly. React at 180℃ for 12h using a high-temperature hydrothermal reaction. Filter to collect the solid, wash with ethanol, and dry at 60℃ to obtain sulfur-doped graphene. S12. 1g of sulfur-doped graphene was dispersed in 50mL of ethanol to prepare a sulfur-doped graphene dispersion. 50mL of the sulfur-doped graphene dispersion, 4.4g of zinc acetate dihydrate and 3.5g of tin chloride pentahydrate were added to 50mL of deionized water. Sodium hydroxide solution was added to adjust the pH to 7.5. 0.1g of barium chloride was added, and the mixture was heated to 180℃ and reacted for 24h. The resulting solid was filtered, washed, dried, and then calcined at 850℃ for 1h in a nitrogen atmosphere to reduce the graphene, thus obtaining a nano-VOC inhibitor.

[0037] The preparation method of the scratch-resistant additive in this embodiment includes the following steps: S21. Add 2.5g of microcrystalline cellulose to 130mL of a mixed solution prepared by mixing 37% hydrochloric acid and acrylic acid in a volume ratio of 1:2. Acid hydrolysis was carried out at room temperature for 10h, followed by heating to 98℃ and reacting for 4h. The supernatant was collected by centrifugation and filtration at 8000rpm. Sodium bicarbonate was added to adjust the pH to 5.5 to precipitate impurities. The supernatant was collected by centrifugation and filtration again at 8000rpm. Dialysis was performed with a molecular cutoff of 15KD to obtain grafted nanocellulose. S22. 18g of 5-methoxy-2-methylindole, 10mL of triethylamine and 100mL of toluene were added to a reaction vessel and stirred to dissolve. 12g of methacryloyl chloride was added under ice bath conditions. The mixture was heated to room temperature and reacted for 24h. Solid impurities were removed by filtration and toluene was removed by rotary evaporation to obtain a scratch-resistant monomer. S23. Add 3g of grafted nanocellulose, 14g of scratch-resistant monomer and 60mL of diethylene glycol butyl ether to a reaction vessel, add 0.3g of azobisisobutyronitrile, heat to 90℃ and react for 6h to obtain a scratch-resistant additive.

[0038] The preparation method of the waterborne acrylic resin in this embodiment includes the following steps: S31. Add 100 mL of propylene glycol methyl ether to the reaction vessel, add monomer mixture one and tetrabutylammonium bromide catalyst under a nitrogen atmosphere and stir. The amount of tetrabutylammonium bromide catalyst added is 3% of the mass of monomer mixture one. Keep the reaction at 160℃ for 4 h and dry by rotary evaporation to obtain the viscosity-reducing precursor. S32. The viscosity-reducing precursor, monomer mixture II, 150 mL of propylene glycol methyl ether and azobisisobutyronitrile were added to a reaction vessel and heated to reflux. The amount of azobisisobutyronitrile added was 3% of the mass of monomer mixture II. The reaction was carried out under nitrogen atmosphere and pressurized to 150 °C for 1 h. Triethylamine was added for neutralization, and deionized water was added. The mixture was stirred at high speed of 5000 rpm for 20 min to obtain waterborne acrylic resin.

[0039] The method for preparing the low-VOC emission acrylic resin composition in this embodiment involves stirring an aqueous acrylic resin, a defoamer, and a leveling agent at 300 rpm for 2 minutes, adding a nano-VOC inhibitor, stirring at 400 rpm for 5 minutes, and then filtering and defoaming through a 300-mesh sieve to obtain the low-VOC emission acrylic resin composition.

[0040] The application of the low-VOC-emission acrylic resin composition in this embodiment is for use in metal protective coatings.

[0041] Comparative Example 1 differs from Example 1 in that the nano-VOC inhibitor is replaced with nano-zinc stannate with an average particle size of 400 nm.

[0042] Comparative Example 2 differs from Example 1 in that the scratch-resistant additive is replaced with microcrystalline cellulose.

[0043] Comparative Example 3 differs from Example 1 in that acrylamide is not added during the preparation of the waterborne acrylic resin.

[0044] Performance testing The VOC content of the low-VOC-emission acrylic resin compositions prepared in each example and comparative example was determined according to GB / T 23985-2009 "Determination of Volatile Organic Compound (VOC) Content in Paints and Varnishes - Difference Method".

[0045] The relative molecular weights of the low-VOC-emission acrylic resin compositions prepared in each example and comparative example were determined by gel permeation chromatography, using tetrahydrofuran as the mobile phase and a flow rate of 1 mL / min.

[0046] According to GB / T 1721-2008 "Determination of Appearance and Transparency of Varnishes, Oils and Diluents", the turbidity of the low-VOC emission acrylic resin compositions prepared in each example and comparative example was observed by visual inspection.

[0047] The test results are shown in Table 1 below:

[0048] Table 1 Properties of acrylic resin compositions

[0049]

[0050] The low-VOC-emission acrylic resin compositions obtained in each embodiment and comparative example were coated onto the surface of a steel plate and dried to obtain a metal protective film sample with a thickness of 10 μm.

[0051] The hardness of the metal protective film samples prepared in each example and comparative example was tested according to GB / T 6739-2022 "Determination of Hardness of Paints and Varnishes by Pencil Method".

[0052] The impact resistance of the metal protective film samples prepared in each example and comparative example was tested according to GB / T 1732-2020 "Test Method for Impact Resistance of Coating Film".

[0053] The adhesion of the metal protective film samples prepared in each example and comparative example was tested according to GB / T 1720-2020 "Determination of Adhesion of Coating Film".

[0054] The test results are shown in Table 2 below:

[0055] Table 2 Performance of Protective Film Samples

[0056]

[0057] As shown in Table 1 above, the relative molecular weight of the acrylic resin compositions obtained in Examples 1-3 is 1.0 × 10⁻⁶. 4 ~1.2×10 4 The VOC content was 26.3-26.7%, and the appearance was a transparent and uniform solution. In Comparative Example 1, the nano-VOC inhibitor was replaced with nano-zinc stannate with an average particle size of 400 nm, which affected light transmission and had a large electron-hole recombination rate, thus inhibiting the VOC catalytic performance. As a result, the VOC content of Example 1 was 33.2%. In Comparative Example 2, the unmodified microcrystalline cellulose had poor compatibility with the resin and was prone to phase separation, resulting in a significant decrease in transparency. This indicates that the acrylic resin composition prepared by the present invention has excellent processing performance and low VOC content. As shown in Table 2 above, after the acrylic resin compositions prepared in Examples 1-3 were used to prepare metal protective film samples, the hardness was 2H, the impact strength was 40 kg·cm, and the adhesion was grade 0. This indicates that the acrylic resin composition prepared by the present invention has excellent scratch resistance and can adhere tightly to the metal surface without falling off.

[0058] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0059] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A low-VOC-emission acrylic resin composition, characterized in that, It is prepared from the following components in parts by weight: 85-95 parts waterborne acrylic resin, 0.5-2 parts nano VOC inhibitor, 0.5-3 parts leveling agent, 0.5-3 parts defoamer and 0.5-2 parts ultraviolet absorber; The waterborne acrylic resin is prepared from the following components in parts by weight: 15-20 parts of monomer mixture one, 85-100 parts of monomer mixture two, 5-10 parts of triethylamine and 90-160 parts of deionized water; The monomer mixture comprises the following raw materials in parts by weight: 4-6 parts acrylic acid, 0.8-1.2 parts 1,1-stilbene and 12-15 parts glycidyl tert-carbonate; The monomer mixture two comprises the following raw materials in parts by weight: 20-30 parts hydroxyethyl methacrylate, 12-18 parts acrylic acid, 18-25 parts methyl acrylate, 16-20 parts butyl acrylate, 3-5 parts diethylaminoethyl methacrylate, 3-5 parts acrylamide, 2-4 parts 1,1-stilbene and 1-5 parts scratch-resistant additives. The preparation method of the nano-VOC inhibitor includes the following steps: S11. Add graphene oxide to deionized water to obtain a graphene oxide mixture, add thioacetamide and stir evenly, heat to hydrothermal reaction, filter to collect solid, wash and dry to obtain sulfur-doped graphene. S12. Sulfur-doped graphene was dispersed in ethanol to obtain a sulfur-doped graphene dispersion. The sulfur-doped graphene dispersion, zinc acetate dihydrate and tin chloride pentahydrate were added to deionized water. Sodium hydroxide solution was added to adjust the pH. Barium chloride was added, and the mixture was heated for hydrothermal reaction. The resulting solid was filtered and washed. The solid was washed and dried. The graphene was calcined and reduced in a nitrogen atmosphere to obtain a nano-VOC inhibitor.

2. The low-VOC emission acrylic resin composition according to claim 1, characterized in that, The ultraviolet absorber is any one of UV-9, UV-3030, and UV-531.

3. The low-VOC emission acrylic resin composition according to claim 1, characterized in that, The concentration of the graphene oxide mixture in S11 is 6-10 mg / mL, and the mass ratio of graphene oxide to thioacetamide is 12-18:7-8. It is subjected to a high-temperature hydrothermal reaction at 170-180℃ for 10-12 h, washed with ethanol, and dried at 60-80℃. In S12, the mass ratio of sulfur-doped graphene, zinc acetate, tin chloride, and barium chloride is 1-1.1:4.4:3.5:0.08-0.

1. Sodium hydroxide solution is added to adjust the pH to 7-7.5, and the mixture is heated to 160-180℃ for 20-24 h, followed by calcination at 750-850℃ for 1-2 h.

4. The low-VOC emission acrylic resin composition according to claim 1, characterized in that, The method for preparing the scratch-resistant additive includes the following steps: S21. Microcrystalline cellulose was added to a mixed solution of 37% hydrochloric acid and acrylic acid for acid hydrolysis. The reaction was heated, centrifuged and filtered to collect the supernatant. Sodium bicarbonate was added to adjust the pH and precipitate impurities. The supernatant was collected again by centrifugation and filtration and dialyzed to obtain grafted nanocellulose. S22. 5-Methoxy-2-methylindole, triethylamine and toluene were added to a reaction vessel and stirred to dissolve. Methacryl chloride was added under ice bath conditions, and the reaction was heated. Solid impurities were removed by filtration, and toluene was removed by rotary evaporation to obtain a scratch-resistant monomer. S23. Grafted nanocellulose, scratch-resistant monomer and diethylene glycol butyl ether are added to a reaction vessel, azobisisobutyronitrile is added, and the mixture is heated to react and obtain a scratch-resistant additive.

5. The low-VOC emission acrylic resin composition according to claim 4, characterized in that, In S21, the volume ratio of 37% hydrochloric acid to acrylic acid is 1:

2. The amount of microcrystalline cellulose added is 1-2% of the mass of the mixed solution of hydrochloric acid and acrylic acid. Acid hydrolysis is performed at room temperature for 10-12 hours, followed by reaction at 95-100℃ for 4-6 hours. The mixture is then centrifuged and filtered at 6000-8000 rpm, and sodium bicarbonate is added dropwise to adjust the pH to 5-5.

5. The dialysis molecular cutoff is 8-15 KD. In S22, 5-methoxy-2-methylindole and methylpropene... The ratio of acyl chloride, triethylamine and toluene is (16~18) g: (10~12) g: (10~11) mL: (70~100) mL, and the reaction is carried out at room temperature for 20~24 h; the ratio of grafted nanocellulose, scratch-resistant monomer, diethylene glycol butyl ether and azobisisobutyronitrile in S23 is (1~3) g: (12~15) g: (50~60) mL: (0.1~0.3) g, and the reaction is carried out at 80~90℃ for 4~6 h.

6. The low-VOC emission acrylic resin composition according to claim 1, characterized in that, The preparation method of the waterborne acrylic resin includes the following steps: S31. Add a high-boiling-point solvent to a reaction vessel, add monomer mixture I and tetrabutylammonium bromide catalyst under a nitrogen atmosphere, stir, keep the reaction at a constant temperature, and dry by rotary evaporation to obtain a viscosity-reducing precursor. S32. The viscosity-reducing precursor, monomer mixture II, high-boiling-point solvent and azobisisobutyronitrile are added to a reaction vessel and heated to reflux. The reaction is carried out under pressure and temperature in a nitrogen atmosphere. Triethylamine is added for neutralization. Deionized water is added and stirred at high speed to obtain an aqueous acrylic resin.

7. The low-VOC emission acrylic resin composition according to claim 6, characterized in that, The high-boiling-point solvents in S31 and S32 are any one of diethylene glycol butyl ether, diethylene glycol ethyl ether, and propylene glycol methyl ether; the amount of tetrabutylammonium bromide catalyst added in S31 is 1-3% of the mass of monomer mixture one, and the reaction is carried out at 150-160℃ for 4-6 hours; the amount of azobisisobutyronitrile added in S32 is 1-3% of the mass of monomer mixture two, and the reaction is carried out at 140-150℃ for 1-2 hours, followed by the addition of deionized water and high-speed stirring at 4000-5000 rpm for 10-20 minutes.

8. The method for preparing the low-VOC emission acrylic resin composition according to any one of claims 1-7, characterized in that, Includes the following steps: A water-based acrylic resin, defoamer, and leveling agent are stirred at 300-400 rpm for 1-2 minutes. A nano-VOC inhibitor is added, and the mixture is stirred at 400-600 rpm for 3-5 minutes. The mixture is then filtered through a 200-300 mesh sieve to remove bubbles and obtain a low-VOC-emission acrylic resin composition.

9. The application of the low-VOC emission acrylic resin composition according to any one of claims 1-7, characterized in that, Used to prepare protective coatings for metals.

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