Multi-purpose varnish emulsion with excellent water white resistance, high hardness and high brightness

Abstract

The invention belongs to the technical field of coatings, and discloses a multipurpose varnish emulsion with excellent water whitening resistance, high hardness and brightness as well as a preparation method and application of the multipurpose varnish emulsion. The invention relates to a water-based adhesive which is prepared from the following components in percentage by mass: 8 to 12 percent of butyl acrylate, 30 to 35 percent of methyl methacrylate, 0.5 to 1.5 percent of diacetone acrylamide, 0.25 to 0.75 percent of adipic dihydrazide, 0.5 to 1 percent of allyl methacrylate, 0.5 to 1.5 percent of polyfunctional group crosslinking monomer, 0.5 to 1 percent of organic silicon crosslinking monomer, 0.2 to 0.5 percent of reactive emulsifier, 0.2 to 0.5 percent of persulfate and 50 to 55 percent of water. The cross-linking monomers, the emulsifier and the persulfate have specific selectable types. The preparation method comprises the steps of raw material preparation, pre-emulsification, seed emulsion preparation, polymerization reaction, heat preservation and curing, post-treatment and filtration, and the stirring speed, the reaction temperature and the dropwise adding time need to be accurately controlled. The emulsion is excellent in water whitening resistance and high in hardness, has a light effect, and is suitable for multiple scenes and high in practicability.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to single-component acrylic polymer emulsion technology, and more particularly to an excellent water-resistant, high-hardness, glossy, multi-purpose clear varnish emulsion. Background Technology

[0002] With the increasing demand for building decoration and substrate protection, exterior wall coatings such as stone-like paint, textured paint, and multi-colored stone-like paint, as well as functional coatings such as wood coatings and floor coatings, are being used more and more widely. Among them, varnish emulsion, as the core film-forming component of coatings, directly determines the durability, appearance, and protective effect of the coating.

[0003] In existing technologies, such as the "hydrophobic, high-hardness, water-resistant acrylate emulsion" disclosed in patent application CN108383937A, although it has solved the problem of "contradiction between hardness and water resistance" in acrylate emulsions to a certain extent by using hard monomers such as methyl methacrylate and styrene, and vinyltrimethoxysilane crosslinking monomers, achieving the performance of not softening in 50℃ tap water for 24 hours and not changing color in 90℃ distilled water for 12 hours, and simplifying the preparation process by using a heated self-reaction method, this technology still has obvious shortcomings: First, the water-resistant whitening performance is limited, only meeting the short-term water resistance requirement of 12 hours, and cannot cope with the problem of coating whitening and loosening in long-term humid environments such as continuous rainy days; Second, it does not mention the anti-ultraviolet performance, and the coating is prone to yellowing after long-term outdoor use, affecting the appearance durability; Third, there is no clear quantitative indicator of hardness (such as pencil hardness), and it does not achieve a high gloss effect, making it difficult to meet the gloss requirements of wood coatings, floor coatings, etc.; Fourth, its application scope is limited to the field of stone paint, and it cannot adapt to the protection needs of substrates such as wood coatings and floor coatings.

[0004] Furthermore, conventional single-component acrylic emulsions in the industry generally suffer from low hardness (typically only HB grade), poor water-whitening resistance, coating swelling and peeling due to water absorption by hydrophilic additives (such as non-reactive emulsifiers), and insufficient gloss. While two-component emulsions offer superior performance, they are costly and complex to apply. Oil-based emulsions, although meeting hardness and gloss standards, suffer from poor environmental performance. Therefore, developing a single-component clear varnish emulsion that combines long-term water-whitening resistance, high hardness, high gloss, UV resistance, versatility, and environmental friendliness has become a pressing technical challenge for the industry. Summary of the Invention

[0005] To address the shortcomings of existing technologies, such as short water-resistant whitening time, lack of UV resistance, insufficient gloss and hardness, and narrow application range, as well as the limitations of single-component emulsions and the high cost and poor environmental performance of two-component and oil-based emulsions, this invention provides a superior water-resistant whitening, high-hardness, glossy, multi-purpose clear varnish emulsion, achieved through the following technical solution: A superior water-resistant, high-hardness, glossy, multi-purpose clear varnish emulsion, wherein the emulsion is an acrylic polymer emulsion, and the components and their mass percentages are as follows: butyl acrylate: 8-12%, methyl methacrylate: 30-35%, diacetone acrylamide: 0.5-1.5%, adipate dihydrazide: 0.25-0.75%, allyl methacrylate: 0.5-1%, multifunctional crosslinking monomer: 0.5-1.5%, organosilicon crosslinking monomer: 0.5-1%, reactive emulsifier: 0.2-0.5%, persulfate: 0.2-0.5%, and water: 50-55%.

[0006] Furthermore, the multifunctional crosslinking monomer is one or more of the following in any proportion: trimethylolpropane trimethacrylate, dipropylene glycol diacrylate, ethoxylated trimethylolpropane triacrylate, and isoborneol acrylate.

[0007] Furthermore, the organosilicon crosslinking monomer is one or more of vinyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and γ-glycidyl ether propyltrimethoxysilane in any proportion.

[0008] Furthermore, the reactive emulsifier is one or more of sodium propylene polysulfide succinate, sodium methyl allyl hydroxypropanesulfonate, and allyloxy fatty alcohol polyoxyethylene ether (10) ammonium sulfate in any proportion.

[0009] Furthermore, the persulfate is one or more of ammonium persulfate, sodium persulfate, and potassium persulfate in any proportion.

[0010] The preparation method of the superior water-resistant, high-hardness, glossy, multi-purpose varnish emulsion described above includes the following steps: (1) Raw material preparation: Weigh each component according to the above mass percentage, and mix butyl acrylate, methyl methacrylate, diacetone acrylamide, allyl methacrylate, multifunctional crosslinking monomer, and organosilicon crosslinking monomer evenly to form an oil phase mixture; Dissolve persulfate in a portion of water to prepare an initiator solution with a mass concentration of 0.5–1.2%, and set aside for later use; Dissolve the reactive emulsifier in the remaining water to prepare an aqueous emulsifier solution; (2) Pre-emulsification: The oil phase mixture prepared in step (1) is slowly added to the aqueous phase emulsifier solution and emulsified for 20 to 30 minutes at a stirring speed of 300 to 500 r / min to form a stable pre-emulsion for later use; (3) Seed emulsion preparation: Add 10-15% of the total amount of the pre-emulsion prepared in step (2) to a four-necked reactor equipped with a stirrer, thermometer, dropping funnel and reflux condenser, turn on the stirrer, raise the temperature to 70-80℃, add 10-15% of the total amount of the initiator solution, stir evenly, keep the reaction at the temperature for 15-20 minutes until the system shows obvious blue light, and a seed emulsion is formed; (4) Polymerization reaction: Under the condition of 75-85℃, the remaining pre-emulsion in step (2) and the remaining initiator solution in step (1) are simultaneously added to the reaction vessel through a dropping funnel, and the dropping time is controlled to be 2-3 hours. During the dropping process, the reaction temperature is kept stable. (5) Incubation and maturation: After the addition is complete, maintain the temperature at 75-85℃ and continue the reaction for 1-2 hours to ensure that the monomers are fully polymerized; (6) Post-treatment: Cool the reaction system to 40-50℃, add adipic acid dihydrazide, stir for 30-40 minutes until completely dissolved, then adjust the pH of the system to 6.5-7.5, and continue stirring for 15-20 minutes; (7) Filtration: Cool the system to room temperature and filter it through a 100-200 mesh filter cloth to obtain the excellent water-resistant white high-hardness gloss multi-purpose varnish emulsion.

[0011] The application of the superior water-resistant, high-hardness, glossy, multi-purpose clear varnish emulsion described in the above scheme, wherein the emulsion is used to formulate clear varnishes for stone paint, textured paint, multi-colored imitation stone paint, wood paint, or floor paint.

[0012] Compared with the prior art, the present invention has the following advantages: 1. Significantly improved water resistance and whitening performance: Through the synergistic effect of "reactive emulsifier + diacetone acrylamide + adipate dihydrazide + allyl methacrylate", emulsifier migration is avoided. The cross-linking of diacetone acrylamide and adipate dihydrazide during film formation at room temperature and the cross-linking of allyl methacrylate, along with the improvement of water resistance by organosilicon monomers through hydrophobic groups, ensures that the coating does not turn white after being soaked in water for 30 days, solving the problem of coating whitening and peeling in long-term humid environments; 2. Balancing high hardness and high gloss: Methyl methacrylate is used as a hard monomer, combined with multifunctional cross-linked monomers to form a three-dimensional network structure, which enhances the cross-linking density. The hardness of the paint film reaches 3-4H pencil lead hardness, far exceeding the HB grade hardness of single-component emulsions in the industry. At the same time, the emulsion has small particle size and high cross-linking density, resulting in high light refraction and a 60° mirror gloss of over 90°, meeting the appearance requirements of wood coatings and floor coatings. 3. Excellent UV resistance and weather resistance: Relying on the UV resistance of methyl methacrylate and the bond strengthening effect of organosilicon crosslinking monomers, it can resist UV exposure for up to 2000 hours without yellowing, solving the problem of yellowing of outdoor coatings and extending the service life of the coating. 4. Hydrophobic, stain-resistant, and highly versatile: Diacetone acrylamide, multifunctional crosslinking monomers, and organosilicon crosslinking monomers synergistically undergo crosslinking coupling hybridization reactions to form a "lotus leaf effect" emulsion with a contact angle >95°. The stain resistance is less than 10% according to the national standard HG / T5065-2016. It is also suitable for multiple fields such as real stone paint, textured paint, multi-color imitation stone paint, wood paint, and floor paint, overcoming the limitation of existing technologies that are only applicable to real stone paint. 5. Excellent cost performance and environmental friendliness: The single-component system does not require complex formulation and has a lower cost than two-component emulsions; the water-based system has no volatile organic pollutants and is more environmentally friendly than oil-based emulsions, which is in line with the current "green" development trend of the coating industry. Detailed Implementation

[0013] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention are further described below with reference to embodiments, but the present invention is not limited to these embodiments.

[0014] The testing standards for various indicators of this invention are as follows: water resistance: GB / T1733-1993, UV resistance: GB / T1865-2009 (Δb value test, 2000h irradiation), pencil hardness: GB / T6739-2022, 60° gloss: GB / T9754-2007, stain resistance: HG / T5065-2016 (B method), adhesion: GB / T9286-2021.

[0015] All reagents used in this invention are commercially available conventional products.

[0016] Test conditions: Film thickness control Wet film thickness: 80-90 μm (wire bar coater), ensure dry film thickness 40±5 μm (normal range for clear coat); Drying and maintenance conditions Initial drying: Surface dry at room temperature (23±2℃, relative humidity 50±5%) for 4 hours (no stickiness when lightly touched with fingers); Practical application: 24 hours of practical application in a normal temperature environment; Curing: Cured in a 50℃ constant temperature oven for 48 hours, then cooled to room temperature before testing; Test substrate Water-resistant / UV-resistant / Stain-resistant: 150mm×70mm×5mm asbestos-free cement board (Biaogeda), first apply multi-color imitation stone paint (dry film thickness 1.5mm, commercially available standard), cure at room temperature for 7 days, then apply clear varnish; Pencil hardness: 150mm×50mm×5mm pine substrate (sanded to Ra≤0.8μm); Adhesion: 200mm×200mm×10mm cement floor substrate (grinded smooth and free of dust).

[0017] Example 1 The superior water-resistant, high-hardness, glossy, multi-purpose clear varnish emulsion of this embodiment has the following components and mass percentages: butyl acrylate 9%, methyl methacrylate 32%, diacetone acrylamide 1.1%, adipate dihydrazide 0.5%, allyl methacrylate 0.6%, trimethylolpropane trimethacrylate 1.0%, γ-methacryloyloxypropyltrimethoxysilane 0.8%, sodium methyl allyl hydroxypropanesulfonate 0.3%, potassium persulfate 0.2%, and water 54.5%.

[0018] Preparation method (1) Raw material preparation: Weigh each component according to the above mass percentage, mix butyl acrylate, methyl methacrylate, diacetone acrylamide, allyl methacrylate, trimethylolpropane trimethacrylate, and γ-methacryloyloxypropyltrimethoxysilane and stir for 15 minutes to form a homogeneous oil phase mixture; dissolve sodium methyl allyl hydroxypropanesulfonate in 24.5% water to prepare an aqueous emulsifier solution; dissolve potassium persulfate in 30% water to prepare an initiator solution for later use; (2) Pre-emulsification: The above oil phase mixture is slowly added to the aqueous phase emulsifier solution and emulsified for 25 minutes with a stirring speed of 400 r / min to form a stable pre-emulsion without stratification, which is then ready for use. (3) Seed emulsion preparation: Add 12% of the total amount of pre-emulsion to a four-necked reactor equipped with a stirrer, thermometer, dropping funnel and reflux condenser, turn on the stirrer and heat to 75°C, add 12% of the total amount of initiator solution, stir evenly, keep the reaction at the temperature for 18 minutes until the system shows obvious blue light, and a seed emulsion is formed. (4) Polymerization reaction: Raise the temperature of the reactor to 80°C, and simultaneously add the remaining 88% of the pre-emulsion and the remaining 88% of the initiator solution through a dropping funnel. Control the dropping time to 2.5 hours, and keep the temperature fluctuation within ±1°C during the dropping process. (5) Incubation and ripening: After the addition is complete, continue the reaction at 80°C for 1.5 hours; (6) Post-treatment: Cool the reaction system to 45°C, add adipic acid dihydrazide, stir for 35 minutes until completely dissolved, adjust the pH of the system to 7.0 with 10% ammonia water, and continue stirring for 18 minutes; (7) Filtration: Cool the system to room temperature and filter it through a 150-mesh filter cloth to obtain the varnish emulsion.

[0019] Example 2 The excellent water-resistant, high-hardness, glossy, multi-purpose clear varnish emulsion of this embodiment has the following components and mass percentages: butyl acrylate 11%, methyl methacrylate 31%, diacetone acrylamide 0.9%, adipate dihydrazide 0.4%, allyl methacrylate 0.8%, dipropylene glycol diacrylate 0.7%, ethoxylated trimethylolpropane triacrylate 0.5%, vinyltrimethoxysilane 0.6%, allyloxy fatty alcohol polyoxyethylene ether (10) ammonium sulfate 0.4%, ammonium persulfate 0.3%, and water 53.4%.

[0020] Preparation method (1) Raw material preparation: Weigh each component according to the above mass percentage, mix butyl acrylate, methyl methacrylate, diacetone acrylamide, allyl methacrylate, dipropylene glycol diacrylate, ethoxylated trimethylolpropane triacrylate, and vinyltrimethoxysilane and stir for 20 minutes to form a homogeneous oil phase mixture; dissolve allyloxy fatty alcohol polyoxyethylene ether (10) ammonium sulfate in 23.4% water to prepare an aqueous emulsifier solution; dissolve ammonium persulfate in 30% water to prepare an initiator solution for later use; (2) Pre-emulsification: The above oil phase mixture is slowly added to the aqueous phase emulsifier solution and emulsified for 22 minutes with a stirring speed of 350 r / min to form a stable pre-emulsion without stratification, which is then set aside. (3) Seed emulsion preparation: Add 10% of the total amount of pre-emulsion to a four-necked reactor equipped with a stirrer, thermometer, dropping funnel and reflux condenser, turn on the stirrer and heat to 72°C, add 10% of the total amount of initiator solution, stir evenly, keep the reaction at the temperature for 15 minutes until the system shows obvious blue light, and a seed emulsion is formed. (4) Polymerization reaction: Raise the temperature of the reactor to 78°C, and simultaneously add the remaining 90% of the pre-emulsion and the remaining 90% of the initiator solution through a dropping funnel. Control the dropping time to 2.2 hours, and keep the temperature fluctuation within ±1°C during the dropping process. (5) Incubation and ripening: After the addition is complete, maintain the temperature at 78°C and continue the reaction for 1.2 hours; (6) Post-treatment: Cool the reaction system to 42°C, add adipic acid dihydrazide, stir for 32 minutes until completely dissolved, adjust the pH of the system to 6.8 with 10% ammonia water, and continue stirring for 15 minutes; (7) Filtration: Cool the system to room temperature and filter it through a 120-mesh filter cloth to obtain the varnish emulsion.

[0021] Example 3 The superior water-resistant, high-hardness, glossy, multi-purpose clear varnish emulsion of this embodiment has the following components and mass percentages: butyl acrylate 8%, methyl methacrylate 35%, diacetone acrylamide 1.5%, adipate dihydrazide 0.75%, allyl methacrylate 1.0%, isoborneol acrylate 1.5%, γ-glycidyl ether propyltrimethoxysilane 1.0%, propylene polysulfide sodium succinate 0.5%, sodium persulfate 0.5%, and water 0.25%.

[0022] Preparation method (1) Raw material preparation: Weigh each component according to the above mass percentage, mix butyl acrylate, methyl methacrylate, diacetone acrylamide, allyl methacrylate, isoborneol acrylate, and γ-glycidyl ether propyltrimethoxysilane and stir for 18 minutes to form a homogeneous oil phase mixture; dissolve sodium propylene polysulfide succinate in 20.25% water to prepare an aqueous emulsifier solution; dissolve sodium persulfate in 30% water to prepare an initiator solution for later use; (2) Pre-emulsification: The above oil phase mixture is slowly added to the aqueous phase emulsifier solution and emulsified for 30 minutes with a stirring speed of 500 r / min to form a stable pre-emulsion without stratification, which is then ready for use. (3) Seed emulsion preparation: Add 15% of the total amount of pre-emulsion to a four-necked reactor equipped with a stirrer, thermometer, dropping funnel and reflux condenser, turn on the stirrer and heat to 80°C, add 15% of the total amount of initiator solution, stir evenly, keep warm for 20 minutes until the system shows obvious blue light, and seed emulsion is formed. (4) Polymerization reaction: Raise the temperature of the reactor to 85°C, and simultaneously add the remaining 85% of the pre-emulsion and the remaining 85% of the initiator solution through a dropping funnel. Control the dropping time to 3.0 hours, and keep the temperature fluctuation within ±1°C during the dropping process. (5) Incubation and ripening: After the addition is complete, continue the reaction at 85°C for 2.0 hours; (6) Post-treatment: Cool the reaction system to 50°C, add adipic acid dihydrazide, stir for 40 minutes until completely dissolved, adjust the pH of the system to 7.5 with 10% ammonia water, and continue stirring for 20 minutes; (7) Filtration: Cool the system to room temperature and filter it through a 200-mesh filter cloth to obtain the varnish emulsion.

[0023] Example 4 The superior water-resistant, high-hardness, glossy, multi-purpose clear varnish emulsion of this embodiment has the following components and mass percentages: butyl acrylate 10%, methyl methacrylate 33%, diacetone acrylamide 0.7%, adipate dihydrazide 0.3%, allyl methacrylate 0.5%, trimethylolpropane trimethacrylate 0.6%, isoborneol acrylate 0.4%, vinyltrimethoxysilane 0.5%, γ-methacryloyloxypropyltrimethoxysilane 0.4%, sodium methyl allyl hydroxypropanesulfonate 0.2%, propylene polysulfide sodium succinate 0.2%, ammonium persulfate 0.1%, potassium persulfate 0.2%, and water 52.9%.

[0024] Preparation method (1) Raw material preparation: Weigh each component according to the above mass percentage, mix butyl acrylate, methyl methacrylate, diacetone acrylamide, allyl methacrylate, trimethylolpropane trimethacrylate, isoborneol acrylate, vinyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane and stir for 16 minutes to form a homogeneous oil phase mixture; dissolve sodium methyl allyl hydroxypropanesulfonate and sodium propylene polysulfide succinate together in 22.9% water to prepare an aqueous emulsifier solution; dissolve ammonium persulfate and potassium persulfate together in 30% water to prepare an initiator solution for later use; (2) Pre-emulsification: The above oil phase mixture is slowly added to the aqueous phase emulsifier solution and emulsified for 28 minutes with a stirring speed of 450 r / min to form a stable pre-emulsion without stratification, which is then ready for use. (3) Seed emulsion preparation: Add 13% of the total amount of pre-emulsion to a four-necked reactor equipped with a stirrer, thermometer, dropping funnel and reflux condenser, turn on the stirrer and heat to 76°C, add 13% of the total amount of initiator solution, stir evenly, keep the reaction at the temperature for 17 minutes until the system shows obvious blue light, and a seed emulsion is formed. (4) Polymerization reaction: The temperature of the reactor is raised to 82°C, and the remaining 87% of the pre-emulsion and the remaining 87% of the initiator solution are added dropwise through a dropping funnel. The dropping time is controlled to be 2.7 hours, and the temperature fluctuation is kept within ±1°C during the dropping process. (5) Incubation and ripening: After the addition is complete, maintain the temperature at 82°C and continue the reaction for 1.6 hours; (6) Post-treatment: Cool the reaction system to 46°C, add adipic acid dihydrazide, stir for 36 minutes until completely dissolved, adjust the pH of the system to 7.2 with 10% ammonia water, and continue stirring for 17 minutes; (7) Filtration: Cool the system to room temperature and filter it through a 180-mesh filter cloth to obtain the varnish emulsion.

[0025] Example 5 The excellent water-resistant, high-hardness, glossy, multi-purpose clear varnish emulsion of this embodiment has the following components and mass percentages: butyl acrylate 12%, methyl methacrylate 30%, diacetone acrylamide 1.2%, adipate dihydrazide 0.6%, allyl methacrylate 0.7%, ethoxylated trimethylolpropane triacrylate 1.3%, γ-glycidyl ether propyltrimethoxysilane 0.7%, allyloxy fatty alcohol polyoxyethylene ether (10) ammonium sulfate 0.3%, sodium persulfate 0.4%, and water 52.8%.

[0026] Preparation method (1) Raw material preparation: Weigh each component according to the above mass percentage, mix butyl acrylate, methyl methacrylate, diacetone acrylamide, allyl methacrylate, ethoxylated trimethylolpropane triacrylate, and γ-glycidyl ether propyltrimethoxysilane and stir for 17 minutes to form a homogeneous oil phase mixture; dissolve allyloxy fatty alcohol polyoxyethylene ether (10) ammonium sulfate in 22.8% water to prepare an aqueous emulsifier solution; dissolve sodium persulfate in 30% water to prepare an initiator solution for later use; (2) Pre-emulsification: The above oil phase mixture is slowly added to the aqueous phase emulsifier solution and emulsified for 26 minutes at a stirring speed of 380 r / min to form a stable pre-emulsion without stratification, which is then set aside. (3) Seed emulsion preparation: Add 14% of the total amount of pre-emulsion to a four-necked reactor equipped with a stirrer, thermometer, dropping funnel and reflux condenser, turn on the stirrer and heat to 78°C, add 14% of the total amount of initiator solution, stir evenly, keep the reaction at the temperature for 19 minutes until the system shows obvious blue light, and form seed emulsion. (4) Polymerization reaction: The temperature of the reactor is raised to 83°C, and the remaining 86% of the pre-emulsion and the remaining 86% of the initiator solution are added dropwise through a dropping funnel. The dropping time is controlled to be 2.4 hours, and the temperature fluctuation during the dropping process is kept not more than ±1°C. (5) Incubation and ripening: After the addition is complete, maintain the temperature at 83°C and continue the reaction for 1.4 hours; (6) Post-treatment: Cool the reaction system to 48°C, add adipic acid dihydrazide, stir for 38 minutes until completely dissolved, adjust the pH of the system to 7.3 with 10% ammonia water, and continue stirring for 19 minutes; (7) Filtration: Cool the system to room temperature and filter it through a 160-mesh filter cloth to obtain the varnish emulsion.

[0027] Table 1 Performance data for Examples 1-5 Based on existing technology and component deficiency design Comparative Example 1: Referencing the existing patent CN108383937A formulation (lacking the DAAM-ADH crosslinking system) The components and mass percentages of the varnish emulsion in this comparative example are as follows: butyl acrylate 10.0%, methyl methacrylate 25.0%, styrene 8.0%, vinyltrimethoxysilane 0.5%, allyl methacrylate 0.5%, non-reactive emulsifier (sodium dodecylbenzene sulfonate) 0.3%, ammonium persulfate 0.3%, and water 55.4%.

[0028] Preparation method: The preparation steps are completely consistent with those in Examples 1-5 (pre-emulsification, seed emulsion preparation, polymerization reaction, etc. are the same), only the raw material components are adjusted according to the above proportions, as follows: Raw material preparation: butyl acrylate, methyl methacrylate, styrene, vinyltrimethoxysilane, and allyl methacrylate are mixed evenly to form an oil phase; sodium dodecylbenzenesulfonate is dissolved in 25.4% water to form an aqueous emulsifier solution; ammonium persulfate is dissolved in 30% water to prepare an initiator solution.

[0029] Pre-emulsification: Slowly add the oil phase to the water phase and stir at 400 r / min for 25 minutes to form a pre-emulsion.

[0030] Seed emulsion: Add 12% of the total amount of pre-emulsion to a four-necked reactor, heat to 75°C, add 12% initiator solution, and keep warm for 18 minutes until blue light appears.

[0031] Polymerization reaction: The remaining pre-emulsion and initiator solution were added dropwise simultaneously at 80°C, and the addition was completed in 2.5 hours.

[0032] Incubation and curing: React at 80℃ for 1.5 hours.

[0033] Post-treatment: Cool to 45℃, directly adjust pH to 7.0 (without adipic acid dihydrazide), and stir for 18 minutes.

[0034] Filtration: Filtered through a 150-mesh filter cloth at room temperature to obtain a varnish emulsion.

[0035] Comparative Example 2: Industry-standard single-component acrylic varnish emulsion (non-crosslinking monomer + non-reactive emulsifier) The components and mass percentages of the varnish emulsion in this comparative example are as follows: butyl acrylate 15.0%, methyl methacrylate 25.0%, non-reactive emulsifier (sodium dodecyl sulfate) 0.4%, potassium persulfate 0.3%, and water 59.3%.

[0036] Preparation method: The steps are the same as in the examples, except that the raw material mixing steps are simplified because there are no functional monomers (DAAM, ADH, multifunctional / organosilicon crosslinking monomers): Raw material preparation: butyl acrylate and methyl methacrylate are mixed to form the oil phase; sodium dodecyl sulfate is dissolved in 29.3% water to form the aqueous phase; potassium persulfate is dissolved in 30% water to prepare the initiator solution.

[0037] The pre-emulsification, seed emulsion, polymerization reaction, heat preservation and ripening, post-treatment (only adjusting pH to 7.0), and filtration steps were all the same as in Example 1.

[0038] Comparative Example 3: The DAAM-ADH crosslinking system is missing (other components are consistent with the example). The components and mass percentages of the varnish emulsion in this comparative example are as follows: butyl acrylate 9.0%, methyl methacrylate 33.6%, allyl methacrylate 0.6%, trimethylolpropane trimethacrylate 1.0%, γ-methacryloyloxypropyltrimethoxysilane 0.8%, reactive emulsifier (sodium methyl allyl hydroxypropanesulfonate) 0.3%, potassium persulfate 0.2%, and water 54.5%.

[0039] Preparation method: The process is exactly the same as in Example 1, except that "adding adipic acid dihydrazide and stirring" is omitted in the post-processing step (step 6). Instead, the system is directly cooled to 45°C and the pH is adjusted to 7.0. All other steps (pre-emulsification, seed emulsion, polymerization reaction, etc.) remain unchanged.

[0040] Table 2 Performance data for Comparative Examples 1-3 In summary, the superior water-resistant, high-hardness, glossy, multi-purpose varnish emulsions (Examples 1-5) provided by this invention exhibit stable and excellent performance in all core performance indicators: water resistance reaches level 0, with no abnormalities after 30 days; UV resistance Δb value is as low as 0.5-0.8; pencil hardness covers 3H-4H after 2000 hours; gloss level remains at 91°-94° at 60°; stain resistance is only 6.1%-8.2%; and adhesion is level 0 in all cases (using the cross-cut adhesion test). These properties fully meet the core requirements of outdoor building materials, furniture, and other applications for varnishes that are "weather-resistant, high-hardness, glossy, and easy to clean."

[0041] As can be seen from the correlation between components and performance, the key technical advantage of this invention lies in the construction of a multi-component synergistic system: the crosslinking combination of diacetone acrylamide and adipate dihydrazide is the core to achieve excellent water-whitening resistance. Compared with Comparative Example 3, which lacks this component, the water-whitening resistance drops from level 0 to level 1, while the stain resistance increases to 9.5%. Reactive emulsifiers, such as allyloxy fatty alcohol polyoxyethylene ether ammonium sulfate, replace conventional non-reactive emulsifiers, such as sodium dodecyl sulfate in Comparative Example 2, effectively improving coating adhesion and water resistance. The combination of silane monomers, such as vinyltrimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane, and multi-component crosslinking monomers, such as trimethylolpropane trimethacrylate and isoborneol acrylate, further enhances the coating hardness, gloss, and UV resistance.

[0042] Compared with existing technologies, the present invention has significant performance advantages: Compared with Comparative Example 1 (referring to existing patent formulations: water resistance grade 2, hardness HB, gloss 65°, stain resistance rate 21.7%) and Comparative Example 2 (referring to conventional single-component acrylic varnishes in the industry: water resistance grade 3, hardness HB, gloss 70°, stain resistance rate 25.3%), the present invention achieves a significant improvement in water resistance, hardness, gloss, and stain resistance, while maintaining excellent adhesion, thus solving the technical pain points of traditional varnishes such as "high hardness and brittleness, gloss but not stain-resistant, and weather-resistant but prone to whitening".

[0043] Furthermore, the formulation adjustments in Examples 1-5, such as the amount of butyl acrylate (8%-12%) and the substitution of crosslinking monomers, all maintained excellent performance. This demonstrates that the formulation system of the present invention possesses good flexibility and can be fine-tuned according to the performance emphasis of specific application scenarios, such as higher hardness or lower stain resistance, thus having broad practical application value. The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. An excellent water whitening resistant high hardness gloss multipurpose varnish emulsion, characterized by, The emulsion is an acrylic polymer emulsion, and the components and mass percentages are as follows: butyl acrylate: 8-12%, methyl methacrylate: 30-35%, diacetone acrylamide: 0.5-1.5%, adipic acid dihydrazide: 0.25-0.75%, allyl methacrylate: 0.5-1%, multi-functional crosslinking monomer: 0.5-1.5%, silicone crosslinking monomer: 0.5-1%, reactive emulsifier: 0.2-0.5%, persulfate: 0.2-0.5%, water: 50-55%.

2. The superior water whitening resistant high hardness gloss multi-purpose varnish emulsion according to claim 1, characterized by, The multi-functional crosslinking monomer is one or more of trimethylolpropane trimethacrylate, dipropylene glycol diacrylate, ethoxylated trimethylolpropane triacrylate, and isobornyl acrylate in any proportion.

3. The superior water whitening resistant high hardness gloss multi-purpose varnish emulsion according to claim 1, characterized by, The silicone crosslinking monomer is one or more of vinyl trimethoxysilane, gamma-methacryloyloxypropyl trimethoxysilane, and gamma-glycidoxypropyl trimethoxysilane in any proportion.

4. The superior water whitening resistant high hardness gloss multi-purpose varnish emulsion according to claim 1, characterized by, The reactive emulsifier is one or more of propenyl polysulfide succinate sodium, methyl allyl hydroxypropyl sulfonate sodium, and allyloxy fatty alcohol polyoxyethylene ether (10) ammonium sulfate in any proportion.

5. The superior water whitening resistant high hardness gloss multi-purpose varnish emulsion according to claim 1, characterized by, The persulfate is one or more of ammonium persulfate, sodium persulfate, and potassium persulfate in any proportion.

6. A process for the preparation of the excellent water white high hardness gloss multi-purpose clear varnish emulsion as claimed in any one of claims 1 to 5, characterized in that, The method comprises the following steps: (1) Raw material preparation: weigh each component according to the mass percentages above, mix butyl acrylate, methyl methacrylate, diacetone acrylamide, allyl methacrylate, multi-functional crosslinking monomer, and silicone crosslinking monomer uniformly to form an oil phase mixture; Dissolve the persulfate in part of the water to prepare an initiator solution with a mass concentration of 0.5-1.2%, and reserve it; Dissolve the reactive emulsifier in the remaining water to prepare an aqueous emulsifier solution; (2) Pre-emulsification: slowly add the oil phase mixture prepared in step (1) to the aqueous emulsifier solution, emulsify at a stirring speed of 300-500 r / min for 20-30 minutes to form a stable pre-emulsion, and reserve it; (3) Seed emulsion preparation: add 10-15% of the pre-emulsion prepared in step (2) to a four-necked reaction kettle equipped with a stirrer, thermometer, dropping funnel, and reflux condenser, start stirring, heat to 70-80°C, and add 10-15% of the total amount of initiator solution. After stirring uniformly, keep the temperature for 15-20 minutes until a blue light appears in the system to form a seed emulsion; (4) Polymerization reaction: under the condition of 75-85°C, add the remaining pre-emulsion of step (2) and the remaining initiator solution of step (1) into the reaction kettle through the dropping funnel at the same time, and control the dropping time to be 2-3 hours. Keep the reaction temperature stable during the dropping process; (5) Temperature maintenance and curing: after the dropping is completed, continue to react at 75-85°C for 1-2 hours to ensure that the monomers are fully polymerized; (6) Post-treatment: cool the reaction system to 40-50°C, add adipic acid dihydrazide, and stir for 30-40 minutes until it is completely dissolved. Then adjust the pH value of the system to 6.5-7.5, and continue to stir for 15-20 minutes. (7) filtration: the system is cooled to room temperature, and filtered through 100-200 mesh filter cloth to obtain the excellent water-resistant white high-hardness bright multipurpose varnish emulsion.

7. Use of the excellent water-white high-hardness brilliant multipurpose varnish emulsion according to any one of claims 1 to 5, characterized in that, The emulsion is used for preparing finishing varnish of real stone paint, texture paint, colorful imitation stone paint, wood paint or floor paint.

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