Low-VOC environment-friendly building coating and preparation method thereof

Abstract

The invention discloses a low-VOC (volatile organic compound) environment-friendly building coating and a preparation method thereof in the technical field of coatings, and the method comprises the following steps: firstly stirring and dissolving deionized water, hydroxyethyl cellulose and an ammonium polyacrylate dispersing agent, and then adding rutile titanium dioxide, diatomite and heavy calcium carbonate for dispersing; adding soap-free organic silicon acrylic emulsion, mixing, sequentially adding a VOC adsorbent based on a morpholine modified polymer, a nano photocatalytic composite material with a yolk-shell structure, a mineral oil-based defoaming agent, a benzisothiazolinone preservative and a zinc ion antibacterial agent, and stirring; and finally, adding the associated polyurethane thickener, adjusting the pH value, and filtering. The prepared coating is high in environmental protection property, can effectively adsorb and degrade volatile organic compounds, and has antibacterial and mildew-proof functions.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a low-VOC environmentally friendly architectural coating and its preparation method. Background Technology

[0002] Traditional architectural coatings commonly release volatile organic compounds (VOCs) during production and use. These substances not only severely impact indoor air quality but also harm human health and the environment. With increasing environmental awareness and stricter green building standards, the market demand for environmentally friendly coatings with low VOC content is growing rapidly. For a long time, organic solvents, additives, and some resin materials used in conventional coating formulations have been the main sources of VOCs. Therefore, achieving low-pollution and functional coatings through material innovation and process optimization has become a key focus of technological development in the industry.

[0003] Existing low-VOC coating technologies mostly employ physical adsorption or chemical degradation methods to treat harmful gases, but these methods still suffer from limitations such as limited adsorption capacity, low degradation efficiency, or secondary pollution. For example, some products use adsorbent materials such as activated carbon or zeolite, which may desorb after adsorption saturation, causing repeated pollution. While some photocatalytic materials possess degradation capabilities, they still have shortcomings in visible light responsiveness, stability, and dispersibility. Furthermore, emulsifiers, dispersants, and other additives used in traditional preparation processes may introduce additional VOC components, limiting the improvement of the overall environmental performance of the coating. Summary of the Invention

[0004] The purpose of this invention is to provide a low-VOC environmentally friendly building coating and its preparation method, which solves the technical problems of high VOC release, single purification function and poor durability of existing building coatings, as well as the insufficient environmental protection of traditional formulas.

[0005] The present invention achieves the above objectives through the following technical solutions: A method for preparing a low-VOC environmentally friendly architectural coating, comprising the following steps: S1. First, add deionized water, hydroxyethyl cellulose and ammonium polyacrylate dispersant to a high-speed disperser and stir until completely dissolved; then add rutile titanium dioxide, diatomaceous earth and heavy calcium carbonate and disperse. S2. Then, add the soap-free silicone acrylic emulsion and stir to mix; next, add the VOC adsorbent based on morpholine modified polymer, the nano-photocatalytic composite material with yolk-shell structure, the mineral oil-based defoamer, the benzisothiazolinone preservative and the zinc ion antibacterial agent in sequence, and continue stirring; S3. Finally, add an associative polyurethane thickener, add 2-amino-2-methyl-1-propanol to adjust the pH to 8.5-9.0, and filter.

[0006] In this invention, the preparation of the low-VOC environmentally friendly architectural coating embodies the principle of synergistic effect of multiple functional components. In the basic formulation design, the soap-free organosilicon acrylic emulsion serves as the film-forming substance. The siloxane bonds on its molecular chain form an interpenetrating network structure with the acrylate segments. During the curing process, a dense coating film is formed through silanol condensation, fundamentally reducing VOC release. The composite rheological system composed of hydroxyethyl cellulose and polyurethane thickener forms a three-dimensional network structure through hydrogen bonding and hydrophobic association, which not only ensures the storage stability and application performance of the coating, but also fixes VOC molecules through molecular entanglement. The synergistic effect among functional components is reflected in three mechanisms: First, the morpholine-modified adsorbent captures polar VOC molecules such as aldehydes and ketones released during the coating curing process in real time through its hierarchical porous structure and amino active sites. Its chemical adsorption can firmly fix VOC molecules within the pores. Secondly, yolk-shell photocatalytic materials generate highly oxidizing active species under ambient light triggering, deeply degrading VOC molecules captured by the adsorbent into harmless carbon dioxide and water, thus achieving a cyclical regeneration mechanism of adsorption-degradation. Finally, diatomaceous earth and heavy calcium carbonate, among other mineral fillers, not only enhance the mechanical properties of the coating film, but their natural microporous structure also assists in the physical adsorption of VOC molecules and forms electron transfer channels with the photocatalytic components. The anti-corrosion and antibacterial system inhibits the secondary VOC release caused by the decomposition of organic components by microorganisms through the synergistic bactericidal mechanism of benzisothiazolinone and zinc ions. The entire system maintains an alkaline environment through a pH adjuster, ensuring the active state of the adsorbent's amine groups and promoting the neutralization of acidic intermediates produced by the photocatalytic reaction. This multi-component, multi-mechanism synergistic design enables the coating to continuously eliminate VOCs before and after curing, achieving truly low-VOC environmental characteristics while maintaining excellent coating performance and durability.

[0007] In this invention, the VOC adsorbent based on morpholine-modified polymers employs a molecular structure design that organically combines a porous polymer framework with morpholine functional groups. The innovation of this compound lies in the fact that its tertiary amine group (morpholine ring) can form stable bonds with VOC molecules (such as formaldehyde and benzene compounds) through cation-π interactions and hydrogen bonds. The macroporous-mesoporous hierarchical pore structure provides a huge specific surface area, while the morpholine group acts as a highly efficient molecular trapping site, achieving selective adsorption of VOCs. A photoresponsive side chain is also introduced into the molecular design, enabling it to activate adsorbed VOC molecules under visible light irradiation, promoting their degradation into harmless carbon dioxide and water. This synergistic "adsorption-degradation" mechanism significantly improves the environmental purification capability of the coating while avoiding the secondary pollution problems caused by the saturation of traditional adsorbent materials.

[0008] In this invention, the innovative feature of the yolk-shell structured nano-photocatalytic composite material lies in the organic combination of a magnetic Fe3O4 nanocore, a mesoporous SiO2 shell, and a bimetallic oxide catalytic center, forming a multifunctional synergistic nanoreactor. The unique structure of this compound provides the following advantages: the yolk-shell structure offers a large interfacial area and abundant active sites; the magnetic core allows for the directional enrichment and recycling of the material under an external magnetic field; and the mesoporous shell enables both size-selective catalysis and prevents nanoparticle aggregation and deactivation. The catalytic function of the yolk-shell structured nano-photocatalytic composite material originates from its surface-modified morpholine-functionalized thiolate ligands. These ligands can specifically react with the organic components in the coating system, significantly promoting the cross-linking and curing of the coating film and effectively reducing VOC release during heat curing.

[0009] According to a preferred embodiment of the present invention, in step S1, the stirring speed for stirring until completely dissolved is 800-900 r / min, and the stirring time is 5-10 min.

[0010] According to a preferred embodiment of the present invention, in step S2, the stirring and mixing time is 10-20 min.

[0011] According to a preferred embodiment of the present invention, the preparation method of the VOC adsorbent based on morpholine modified polymer includes: A1, firstly, dissolving glycidyl methacrylate and divinylbenzene in water, adding azobisisobutyronitrile, and reacting under nitrogen protection at 74-76°C to form cross-linked polymer microspheres; subsequently, calcining the obtained polymer microspheres at 390-410°C under nitrogen protection; A2, reacting the calcined porous polymer microspheres with morpholine in ethanol solvent under reflux; after the reaction is completed, collecting the product by centrifugation, washing with ethanol and deionized water alternately, and vacuum drying at 58-62°C to obtain the final product.

[0012] In this invention, the preparation of the VOC adsorbent based on morpholine-modified polymer is based on the synthesis and functionalization modification of porous polymer microspheres. First, glycidyl methacrylate and divinylbenzene undergo a free radical copolymerization reaction in an aqueous phase to form a three-dimensional cross-linked network structure with epoxy groups. Under the action of a thermal initiator, the monomers undergo chain growth and cross-linking reactions, gradually assembling into well-defined polymer microspheres. Divinylbenzene acts as a cross-linking agent, providing a rigid framework to the microspheres, while the epoxy groups provided by glycidyl methacrylate lay the foundation for subsequent modification. Subsequently, high-temperature calcination is carried out in an inert atmosphere. By precisely controlling the pyrolysis temperature, the polymer framework undergoes partial carbonization, forming a highly developed microporous-mesoporous hierarchical pore structure while retaining some epoxy active sites. This process significantly increases the specific surface area and pore volume, providing abundant adsorption sites for VOC molecules. The key modification step lies in the chemical grafting of morpholine molecules onto the porous microspheres. Under ethanol reflux conditions, the epoxy groups retained on the polymer backbone undergo ring-opening addition reactions with the secondary amine groups of the morpholine molecules, forming stable β-hydroxyamine chemical bonds. This reaction firmly anchors the morpholine molecules to the pore surface via covalent bonds, and its nitrogen-containing heterocyclic structure endows the material with strong polar characteristics. The morpholine-modified adsorbent possesses both physical and chemical adsorption mechanisms: the hierarchical porous structure achieves efficient VOC molecule capture through van der Waals forces, while the morpholine groups form directional hydrogen bonds with polar groups such as carbonyl and hydroxyl groups in VOC molecules through nitrogen atoms, exhibiting specific adsorption capacity for polar VOCs such as aldehydes and ketones. This synergistic effect enables the material to achieve high-capacity VOC adsorption at room temperature, and the basicity of the amine groups promotes the chemical fixation of adsorbed acidic VOC molecules.

[0013] According to a preferred embodiment of the present invention, in step A1, the reaction time at 74-76°C is 6-8 hours; the calcination time at 390-410°C is 2-3 hours.

[0014] According to a preferred embodiment of the present invention, in step A2, the reflux reaction time is 10-14 hours.

[0015] According to a preferred embodiment of the present invention, the preparation method of the nano-photocatalytic composite material with a yolk-shell structure includes: B1, dissolving nickel nitrate, copper nitrate, and iron nitrate in deionized water, adding sodium citrate, adding NaOH solution under a nitrogen atmosphere to pH=10.8-11.2, stirring the reaction at 78-82℃, collecting NiCuFe2O4 magnetic nanoparticles by centrifugation, and washing with water and ethanol; B2, dispersing the magnetic nanoparticles in a mixed solvent of ethanol and water, adding hexadecyltrimethylammonium bromide, adding tetraethyl orthosilicate dropwise, reacting under ammonia catalysis to form a core-shell structure; then, heat-treating at 480-520℃ to form a yolk-shell structure; finally, immersing the prepared yolk-shell material in a mixed solution of zinc acetate and tin chloride, ultrasonicating, and calcining at 340-360℃.

[0016] In this invention, the construction of the yolk-shell structured nano-photocatalytic composite material follows the principle of core-shell structure self-assembly and phase transformation. First, a NiCuFe2O4 magnetic core is synthesized using a co-precipitation method. Under alkaline conditions, the metal salt and hydroxyl ions form a composite hydroxide precursor. The growth rate of the crystal nuclei is controlled by the complexation effect of sodium citrate, resulting in uniformly sized ferrite nanoparticles. This ternary metal oxide structure endows the core with superparamagnetic and visible light responsive properties. Subsequently, a silica interlayer is constructed on the core surface using a sol-gel method. Hexadecyltrimethylammonium bromide acts as a template agent to guide the hydrolysis and condensation of tetraethyl orthosilicate, forming a mesoporous silica coating layer. During controlled heat treatment, the difference in thermal expansion coefficients between the core and shell generates interfacial stress, causing the core to partially shrink and separate from the shell, ultimately forming a unique yolk-shell structure. The most crucial photoactive modification is achieved through solution impregnation and calcination. When the yolk-shell structure material is impregnated in a zinc-tin composite salt solution, metal ions penetrate into the mesoporous channels of the silica shell through capillary action. Under ultrasonic treatment, the zinc-tin precursor is uniformly dispersed on the inner surface of the shell. Subsequent calcination decomposes the metal salt into zinc-tin composite oxide, while nanoscale semiconductor quantum dots are formed within the silica shell. This unique structure enables highly efficient separation of photogenerated electron-hole pairs: the core ferrite acts as an electron trapping center, the zinc-tin oxide in the shell provides numerous photocatalytic active sites, and the cavity between the yolk and shell provides a microreactor environment for the photocatalytic reaction. Under visible light irradiation, the composite material degrades VOC molecules through a heterogeneous photocatalytic mechanism. Holes generated by the zinc-tin oxide directly oxidize VOC molecules. In addition, reactive oxygen species such as superoxide radicals and hydroxyl radicals generated during the photocatalytic reaction also participate in the oxidative degradation reaction. The magnetic core endows the material with magnetically separable and recyclable properties.

[0017] According to a preferred embodiment of the present invention, in step B1, the stirring reaction time at 78-82°C is 6-8 hours.

[0018] According to a preferred embodiment of the present invention, in step B2, the reaction time under ammonia catalysis is 12-14 h; the heat treatment time at 480-520℃ is 4-6 h; and the calcination time at 340-360℃ is 3-4 h.

[0019] The present invention also provides a low-VOC environmentally friendly building coating prepared according to the preparation method of the low-VOC environmentally friendly building coating.

[0020] The beneficial effects of this invention are as follows: The low-VOC environmentally friendly architectural coating and its preparation method provided by this invention achieve synergistic improvement of multiple technical effects through innovative material design and precise process control, significantly surpassing the performance of existing conventional products. Its core advantages are reflected in the efficient and long-lasting purification of volatile organic compounds, the comprehensive improvement of the overall coating performance, and the high degree of unity between environmental friendliness and efficiency.

[0021] Specifically, this invention constructs a dual-effect synergistic mechanism of "adsorption-degradation" by introducing a specific adsorbent based on morpholine-modified polymers and a photocatalytic composite material with a unique yolk-shell structure. The adsorbent possesses a high specific surface area and porous structure, which can powerfully capture various volatile organic pollutants and immobilize them within its pores, effectively preventing secondary release. Simultaneously, the yolk-shell structured photocatalytic material, utilizing its unique core-shell hollow space, greatly increases the active sites and reaction interface, enabling efficient catalytic reactions to be activated under visible light, completely decomposing the captured organic matter into harmless substances. The two functional materials complement each other, overcoming the drawback of easy saturation of simple adsorbents and solving the problem of insufficient efficiency of photocatalysts in low-concentration environments, thus achieving long-term and continuous purification of indoor volatile organic compounds.

[0022] Furthermore, this preparation method, through meticulous process control and component optimization, ensures the superior physicochemical properties and stability of the finished coating. The soap-free emulsion system reduces the introduction of volatile organic compounds at the source; stepwise feeding and precise stirring ensure the uniform dispersion and stability of functional nanomaterials, preventing agglomeration and failure; and precise pH adjustment and the selection of associative thickeners achieve an optimal balance between coating storage stability, application leveling, and film density. The final product not only possesses excellent basic properties such as scrub resistance, hiding power, and adhesion, but also exhibits highly effective antibacterial and antifungal capabilities, significantly extending the coating's service life and ensuring hygiene and safety. Detailed Implementation

[0023] The following detailed embodiments are only used to further illustrate this application and should not be construed as limiting the scope of protection of this application. Those skilled in the art can make some non-essential improvements and adjustments to this application based on the above application content.

[0024] The following is information on domestic suppliers of key related equipment and materials: The hydroxyethyl cellulose was purchased from Luzhou Northern Chemical Industry Co., Ltd.

[0025] The ammonium polyacrylate was purchased from Jiangsu Taijia Chemical Co., Ltd.

[0026] The rutile titanium dioxide was purchased from Lomon Billions Group Co., Ltd.

[0027] The diatomite was purchased from Linjiang Xinghui Diatomite Co., Ltd.

[0028] The heavy calcium carbonate was purchased from Sichuan Gongga Xue New Materials Co., Ltd.

[0029] The soap-free silicone acrylic emulsion was purchased from Guangdong Badesi Chemical Co., Ltd.

[0030] The mineral oil-based defoamer was purchased from Foshan Nanhai Datian Chemical Co., Ltd.

[0031] The benzisothiazolinone preservative was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0032] The zinc ion antibacterial agent was purchased from Nanjing Tianshilandun Biotechnology Co., Ltd.

[0033] The associative polyurethane thickener was purchased from Jiangsu Nuon Chemical Co., Ltd.

[0034] The 2-amino-2-methyl-1-propanol was purchased from Wuhan Organic Industry Co., Ltd.

[0035] The glycidyl methacrylate was purchased from Changzhou Tiansheng New Materials Co., Ltd.

[0036] The divinylbenzene was purchased from Jiangsu Yangnong Chemical Group Co., Ltd.

[0037] The azobisisobutyronitrile was purchased from Zibo Qixiang Tengda Chemical Co., Ltd.

[0038] The nitrogen gas was purchased from Hangzhou Hangyang Co., Ltd.

[0039] The morpholine was purchased from Shandong Jinling Chemical Co., Ltd.

[0040] The nickel nitrate was purchased from Jinchuan Group Co., Ltd.

[0041] The copper nitrate was purchased from Jiangxi Copper Corporation Limited.

[0042] The ferric nitrate was purchased from Sichuan Longmang Group Co., Ltd.

[0043] The sodium citrate was purchased from Shandong Yingxuan Industrial Co., Ltd.

[0044] The hexadecyltrimethylammonium bromide was purchased from Hangzhou Ruijing Biotechnology Co., Ltd.

[0045] The tetraethyl orthosilicate was purchased from Zhejiang Xin'an Chemical Group Co., Ltd.

[0046] The ammonia water was purchased from Shandong Hualu Hengsheng Chemical Co., Ltd.

[0047] The zinc acetate was purchased from Hunan Zhuzhou Smelting Group Co., Ltd.

[0048] The tin chloride was purchased from Yunnan Tin Group (Holding) Co., Ltd. Example 1

[0049] First, a VOC adsorbent based on morpholine-modified polymer was prepared. 10g of glycidyl methacrylate and 4g of divinylbenzene were dissolved in 200g of deionized water, and 0.3g of azobisisobutyronitrile was added as an initiator. The mixture was reacted at 75℃ for 7h under nitrogen protection to form cross-linked polymer microspheres. The obtained polymer microspheres were then transferred to a crucible and calcined at 400℃ for 2.5h under nitrogen protection to obtain porous carbon material. The calcined porous polymer microspheres and 30g of morpholine were then added to a three-necked flask containing 200g of ethanol solvent and reacted under reflux for 12h to successfully graft morpholine molecules. After the reaction, the solid product was collected by centrifugation and washed three times alternately with ethanol and deionized water. Finally, it was dried in a vacuum drying oven at 60℃ for 24h to obtain the final morpholine-modified VOC adsorbent. Next, a nano-photocatalytic composite material with a yolk-shell structure was prepared. 2.0 g of nickel nitrate, 1.0 g of copper nitrate, and 4.0 g of ferric nitrate were dissolved in 100 g of deionized water. 1.5 g of sodium citrate was added as a complexing agent. Under a nitrogen atmosphere, sodium hydroxide solution was slowly added to adjust the pH to 11.0. The reaction was carried out in an 80°C water bath with stirring for 7 h. The generated NiCuFe2O4 magnetic nanoparticles were collected by centrifugation and washed three times each with water and ethanol. 1.0 g of the magnetic nanocore was redispersed in a mixed solvent of 50 g ethanol and 50 g water. Add 0.5g of cetyltrimethylammonium bromide as a surfactant, then slowly add 3.0g of tetraethyl orthosilicate, and react for 13h under ammonia catalysis to form a core-shell structure; heat-treat the obtained product in a muffle furnace at 500℃ for 5h to form a yolk-shell hollow structure; finally, immerse 2.0g of the prepared yolk-shell material in a 50g mixed solution containing 1.5g of zinc acetate and 0.8g of tin chloride, sonicate for 30min to fully adsorb the active components, and then calcine at 350℃ for 3.5h to obtain the final photocatalytic composite material.Finally, the coating is prepared. In stage S1, 300g of deionized water, 3.0g of hydroxyethyl cellulose, and 5.0g of ammonium polyacrylate dispersant are added to a high-speed disperser and stirred at 850 rpm for 8 minutes until completely dissolved to form a homogeneous solution. Then, 150g of rutile titanium dioxide, 50g of diatomaceous earth, and 100g of heavy calcium carbonate are added, and high-speed dispersion is maintained for 20 minutes to ensure the pigments are fully ground and dispersed. In stage S2, 350g of soap-free silicone acrylic emulsion is added, and the speed is adjusted to 400 rpm, stirring for 15 minutes to ensure the emulsion and pigment paste are fully mixed. Then, the following are added sequentially: 20g of the VOC adsorbent based on morpholine modified polymer prepared above, 15g of the nano-photocatalytic composite material with yolk-shell structure prepared above, 3.0g of mineral oil-based defoamer, 2.0g of benzisothiazolinone preservative and 5.0g of zinc ion antibacterial agent were added and stirred for 15 minutes to ensure uniform dispersion of all additives. In the S3 stage, 4.0g of associative polyurethane thickener was added, and 3.0g of 2-amino-2-methyl-1-propanol was added to precisely adjust the pH of the system to 8.8. Finally, the mixture was filtered through a 200-mesh filter and packaged to obtain the final low-VOC environmentally friendly architectural coating product. Example 2

[0050] The specific implementation method is the same as in Example 1, except that the preparation of the VOC adsorbent based on morpholine modified polymer is as follows: 8g of glycidyl methacrylate and 3g of divinylbenzene are dissolved in 180g of deionized water, and 0.2g of azobisisobutyronitrile is added. The mixture is reacted at 74°C for 8 hours under nitrogen protection to form cross-linked polymer microspheres. Subsequently, the obtained polymer microspheres are calcined at 390°C for 3 hours under nitrogen protection. The calcined porous polymer microspheres are then refluxed with 25g of morpholine in 180g of ethanol solvent for 10 hours. After the reaction is completed, the product is collected by centrifugation, washed alternately with ethanol and deionized water, and dried under vacuum at 58°C to obtain the final product. Preparation of photocatalytic nanocomposite material with yolk-shell structure: 1.8g nickel nitrate, 0.9g copper nitrate and 3.8g ferric nitrate were dissolved in 90g deionized water, 1.3g sodium citrate was added, and sodium hydroxide solution was added under a nitrogen atmosphere until the pH was 10.8. The mixture was stirred at 78℃ for 8 hours, and the NiCuFe2O4 magnetic nanoparticles were collected by centrifugation and washed with water and ethanol. 0.9g magnetic nanocores were dispersed in a mixed solvent of 45g ethanol and 45g water, 0.4g hexadecyltrimethylammonium bromide was added, and 2.8g tetraethyl orthosilicate was added dropwise. The mixture was reacted under ammonia catalysis for 12 hours to form a core-shell structure. Then, it was heat-treated at 480℃ for 6 hours to form a yolk-shell structure. Finally, 1.8g of the prepared yolk-shell material was immersed in a mixed solution of 45g containing 1.3g zinc acetate and 0.7g tin chloride, sonicated for 25 minutes, and calcined at 340℃ for 4 hours. Preparation of low-VOC environmentally friendly architectural coatings: S1. First, add 280g deionized water, 2.5g hydroxyethyl cellulose, and 4.0g ammonium polyacrylate dispersant to a high-speed disperser and stir at 800 rpm for 10 minutes until completely dissolved; then add 140g rutile titanium dioxide, 45g diatomaceous earth, and 90g heavy calcium carbonate, and disperse for 25 minutes; S2. Next, add 320g soap-free silicone acrylic emulsion and stir at 350 rpm for 20 minutes to mix; then, sequentially add 15g of the VOC adsorbent based on morpholine modified polymer prepared above, 12g of the nano-photocatalytic composite material with yolk-shell structure prepared above, 2.5g mineral oil-based defoamer, 1.5g benzisothiazolinone preservative, and 4.0g zinc ion antibacterial agent, and continue stirring for 10 minutes; S3. Finally, add 3.0g associative polyurethane thickener and 2.5g... The pH was adjusted to 8.5 with 2-amino-2-methyl-1-propanol, and the mixture was filtered to obtain the product. Example 3

[0051] The specific implementation method is the same as in Example 1, except that the VOC adsorbent based on morpholine modified polymer is prepared as follows: 12g of glycidyl methacrylate and 5g of divinylbenzene are dissolved in 220g of deionized water, and 0.4g of azobisisobutyronitrile is added. The mixture is reacted at 76°C for 6 hours under nitrogen protection to form cross-linked polymer microspheres. Subsequently, the obtained polymer microspheres are calcined at 410°C for 2 hours under nitrogen protection. The calcined porous polymer microspheres are then refluxed with 35g of morpholine in 220g of ethanol solvent for 14 hours. After the reaction is completed, the product is collected by centrifugation, washed alternately with ethanol and deionized water, and dried under vacuum at 62°C to obtain the final product. Preparation of a photocatalytic nanocomposite material with a yolk-shell structure: 2.2 g nickel nitrate, 1.1 g copper nitrate, and 4.2 g ferric nitrate were dissolved in 110 g deionized water. 1.7 g sodium citrate was added, and sodium hydroxide solution was added under a nitrogen atmosphere until the pH reached 11.2. The mixture was stirred at 82 °C for 6 hours. The NiCuFe2O4 magnetic nanoparticles were collected by centrifugation and washed with water and ethanol. 1.1 g of magnetic nanocores were dispersed in a mixed solvent of 55 g ethanol and 55 g water. 0.6 g hexadecyltrimethylammonium bromide was added, and 3.2 g tetraethyl orthosilicate was added dropwise. The mixture was reacted under ammonia catalysis for 14 hours to form a core-shell structure. Then, the mixture was heat-treated at 520 °C for 4 hours to form a yolk-shell structure. Finally, 2.2 g of the prepared yolk-shell material was immersed in a mixed solution containing 1.7 g zinc acetate and 0.9 g tin chloride in 55 g of water, sonicated for 35 minutes, and calcined at 360 °C for 3 hours. Preparation of low-VOC environmentally friendly architectural coatings: S1. First, add 320g deionized water, 3.5g hydroxyethyl cellulose, and 6.0g ammonium polyacrylate dispersant to a high-speed disperser and stir at 900 rpm for 5 minutes until completely dissolved; then add 160g rutile titanium dioxide, 55g diatomaceous earth, and 110g heavy calcium carbonate, and disperse for 15 minutes; S2. Next, add 380g soap-free silicone acrylic emulsion and stir at 450 rpm for 10 minutes to mix; then, sequentially add 25g of the VOC adsorbent based on morpholine modified polymer prepared above, 18g of the nano-photocatalytic composite material with yolk-shell structure prepared above, 3.5g mineral oil-based defoamer, 2.5g benzisothiazolinone preservative, and 6.0g zinc ion antibacterial agent, and continue stirring for 20 minutes; S3. Finally, add 5.0g associative polyurethane thickener and 3.5g... The pH was adjusted to 9.0 using 2-amino-2-methyl-1-propanol, and the mixture was filtered to obtain the product.

[0052] Comparative Example 1 The specific implementation method is the same as in Example 1, except that no VOC adsorbent based on morpholine modified polymer is added in step S2.

[0053] Comparative Example 2 The specific implementation method is the same as in Example 1, except that no nano-photocatalytic composite material with a yolk-shell structure is added in S2.

[0054] Comparative Example 3 The specific implementation method is the same as in Example 1, except that neither the VOC adsorbent based on morpholine modified polymer nor the nano-photocatalytic composite material with yolk-shell structure is added in step S2.

[0055] Performance testing The low-VOC environmentally friendly architectural coatings prepared according to Examples 1-3 and Comparative Examples 1-3 were tested according to the following performance testing methods: The coating performance testing was strictly conducted in accordance with relevant national standards. First, sample preparation was performed. The coating sample to be tested was evenly coated onto a pre-treated 150mm×70mm×4mm asbestos cement board using a wire bar coater, with the wet film thickness strictly controlled at 120μm. The coated sample was then placed in a constant temperature and humidity chamber at 23±2℃ and 50±5% relative humidity for 7 days to ensure complete curing before various performance tests could be conducted. For the alkali resistance test, the sample was immersed in a sealed container of saturated calcium hydroxide solution at 23±2℃ for 48 hours. After removal, it was rinsed with deionized water and dried. The coating was observed for any abnormalities such as blistering, powdering, or loss of gloss. For the scrub resistance test, according to standard specifications, a scrub resistance tester and a standard brush were used. The sample was fixed in the test tank, and a scrubbing medium of a specified concentration was added. The sample was repeatedly scrubbed at a rate of 37 cycles per minute, and the final number of scrubs before the substrate was exposed was recorded. The contrast ratio test used a reflectance meter. The coating was evenly applied to a black and white contrast card. After drying, the reflectance of the black and white areas was measured separately, and the ratio was calculated. The adhesion test used the cross-cut test. A 6×6 1mm² grid was drawn on the coating surface using a cross-cutting tool with a 1mm spacing, cutting to the bottom plate. Debris was then gently brushed away with a soft brush, and special adhesive tape was firmly applied to the grid area. The tape was quickly peeled off, and the degree of coating peeling in the grid area was observed and rated. The volatile organic compound (VOC) content test used gas chromatography. A precise 2g sample was placed in a headspace vial and heated at a specific temperature to release volatile substances. Qualitative and quantitative analysis was then performed using gas chromatography, and the total mass of volatile organic compounds per unit volume of coating was calculated. Formaldehyde purification performance testing was conducted in a 1 cubic meter stainless steel sealed test chamber. A glass plate of a specified area coated with the sample was vertically suspended in the center of the chamber. An appropriate amount of formaldehyde standard solution was injected into the chamber using a micro-syringe. A fan was activated to ensure uniform gas mixing. Simulated sunlight was then turned on. Under conditions of 23±2℃, 50±5% relative humidity, and an air exchange rate of 0.5 times / hour, formaldehyde concentrations were measured using a formaldehyde analyzer at 0h, 2h, 4h, 8h, 12h, and 24h. The 24-hour formaldehyde purification efficiency was calculated based on concentration changes. For the durability test of the formaldehyde purification effect, the sample that had completed the initial purification test underwent five consecutive washing treatments. Each treatment included 50 washes of the sample surface using a standard washing medium and a sponge, followed by rinsing with deionized water and air drying. This purification test process was then repeated to evaluate performance durability. All tests were performed in triplicate, and the final result was the arithmetic mean.

[0056] Performance test results: Table 1: Performance test results of each embodiment and comparative example

[0057] As shown in Table 1, the low-VOC environmentally friendly building coatings prepared in Examples 1-3 effectively solve the technical problems of high VOC release, single purification function and poor durability, and insufficient environmental protection of existing building coatings compared with Comparative Examples 1-3. Specifically, the VOC content of Examples 1-3 is controlled below 30 g / L, significantly lower than the 33-42 g / L of Comparative Examples 1-3. This is due to the dual effect of the soap-free emulsion system and functional additives, while the lack of functional components in the comparative groups leads to a significant increase in VOC content. In terms of formaldehyde purification performance, Examples 1-3 exhibit excellent synergistic purification effect, with a 24-hour purification efficiency of 88.3%-94.1%, far superior to Comparative Example 1 (65.2%) and Comparative Example 2 (72.8%), proving that the combined use of morpholine modified adsorbent and yolk-shell photocatalytic material realizes the adsorption-degradation cycle mechanism, breaking through the limitations of single technology; Comparative Example 3, due to the complete lack of functional components, has the lowest purification efficiency (48.6%), further verifying the necessity of the composite functional system. In the durability test, the purification efficiency of Examples 1-3 remained at 82.1%-87.5% after 5 washes, while Comparative Examples 1-3 showed significant performance degradation (35.2%-58.3%). This indicates that the functional materials in the examples achieved a strong bond with the coating through chemical bonding and stable dispersion, overcoming the shortcomings of traditional additives that are prone to deactivation. In summary, the examples, by innovatively introducing bifunctional materials and optimizing the preparation process, achieved multiple technical effects of highly efficient synergistic purification and durable protection while significantly reducing VOC content, comprehensively improving the environmental performance and functional reliability of the coating.

[0058] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a low VOC eco-friendly architectural coating, characterized by the steps of Comprising: S1、First, deionized water, hydroxyethyl cellulose and polyacrylamide salt dispersant are added to a high-speed disperser, and stirred until completely dissolved; then, add rutile titanium dioxide, diatomite and heavy calcium carbonate, and disperse; S2、Then, add soap-free silicone acrylic emulsion, and stir and mix; then, add VOC adsorbent based on morpholine modified polymer, nano photocatalytic composite material with yolk-shell structure, mineral oil based defoaming agent, benzisothiazolinone type preservative and zinc ion antibacterial agent in sequence, and continue to stir; S3、Finally, add associative polyurethane thickener, and adjust the pH value to 8.5-9.0 by adding 2-amino-2-methyl-1-propanol, and filter.

2. The method of claim 1, wherein the low VOC eco-friendly architectural coating is prepared by mixing the base paint, the pigment, the additive, and the solvent. In step S1, the stirring speed for stirring until completely dissolved is 800-900 r / min, and the stirring time is 5-10 min.

3. The method of claim 1, wherein the low VOC eco-friendly architectural coating is prepared by mixing the base paint, the pigment, the additive, and the solvent. In step S2, the stirring and mixing time is 10-20 min.

4. The method for preparing low-VOC environmentally friendly architectural coatings according to claim 1, characterized in that, The preparation method of the VOC adsorbent based on morpholine modified polymer comprises: A1、First, dissolve glycidyl methacrylate and divinylbenzene in water, add azobisisobutyronitrile, and react at 74-76℃ under nitrogen protection to form cross-linked polymer microspheres; then, calcine the obtained polymer microspheres at 390-410℃ under nitrogen protection; A2、The calcined porous polymer microspheres are refluxed with morpholine in an ethanol solvent; after the reaction is completed, the product is collected by centrifugation, washed with ethanol and deionized water alternately, and vacuum dried at 58-62℃ to obtain the final product.

5. The method of preparing low VOC eco-friendly architectural coating according to claim 4, characterized in that, In step A1, the reaction time at 74-76℃ is 6-8h; the calcination time at 390-410℃ is 2-3h.

6. The method of preparing low VOC eco-friendly architectural coating according to claim 4, characterized in that, In step A2, the reflux reaction time is 10-14h.

7. The method for preparing low-VOC environmentally friendly architectural coatings according to claim 1, characterized in that, The preparation method of the nano photocatalytic composite material with yolk-shell structure comprises: B1、Dissolve nickel nitrate, copper nitrate and iron nitrate in deionized water, add sodium citrate, and add NaOH solution under nitrogen atmosphere until pH=10.8-11.2, then stir and react at 78-82℃, collect the NiCuFe2O4 magnetic nanoparticles by centrifugation, and wash with water and ethanol; B2、Disperse the magnetic nanoparticles in a mixed solvent of ethanol and water, add cetyltrimethylammonium bromide, and dropwise add tetraethyl orthosilicate under ammonia water catalysis to form a core-shell structure; then, heat treat at 480-520℃ to form a yolk-shell structure; finally, immerse the prepared yolk-shell material in a mixed solution of zinc acetate and tin chloride, ultrasonic treat, and calcine at 340-360℃.

8. The method of preparing low VOC eco-friendly architectural coating according to claim 7, characterized in that, In step B1, the stirring and reaction time at 78-82℃ is 6-8h. 9.The method for preparing the low-VOC environmentally-friendly architectural paint according to claim 7, characterized in that, In step B2, the reaction time under ammonia water catalysis is 12-14h; the heat treatment time at 480-520℃ is 4-6h; and the calcination time at 340-360℃ is 3-4h.

10. A low VOC, environmentally friendly architectural coating, characterized in that, The low VOC environmentally friendly building coating is prepared according to the preparation method of the low VOC environmentally friendly building coating of any one of claims 1-9.

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