Multifunctional acrylic microgel emulsion as well as preparation method and application thereof

Abstract

The invention discloses a multifunctional acrylic microgel emulsion as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The specific core layer component and the specific shell layer component are selected and have a synergistic effect, so that the anti-sagging property and the self-repairing capability of the acrylic microgel emulsion are remarkably improved; specifically, butyl methacrylate and methyl methacrylate monomers in the core layer endow the emulsion with good flexibility and cohesiveness; high glass transition temperature monomers (methyl methacrylate and styrene) of the shell layer provide higher hardness and corrosion resistance; besides, the functional monomer in the core layer and glycidyl methacrylate in the shell layer are subjected to chemical bonding reaction to form a dynamic cross-linked network structure, so that the self-repairing capability of the acrylic microgel emulsion is further improved; therefore, the multifunctional acrylic microgel emulsion has a good application prospect in coatings.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and particularly relates to a multifunctional acrylic microgel emulsion and a preparation method and application thereof. Background Art

[0002] Acrylic microgels, with their tunable cross-linking structure and nano-effects, show great potential for application in coatings. However, existing acrylic microgel emulsions still have certain limitations, especially in the synergistic optimization of self-healing and anti-sagging properties, which urgently needs breakthroughs.

[0003] For example, Chinese patent application CN109734836A improves the anti-sagging properties of the coating by introducing hydroxyl monomers and cross-linking agents. However, this relies on a static cross-linking network and lacks a dynamic repair mechanism, resulting in the coating being unable to be repaired after damage, with a single function and poor durability. In terms of anti-sagging technology, traditional solutions often rely on thickeners or a single high glass transition temperature (Tg) monomer. For example, Chinese patent application CN114957903A improves anti-sagging properties by using a high dosage of cuprous oxide (>35%). However, the large amount of cuprous ions released into the environment will have an impact on the ecological environment, resulting in poor environmental friendliness and the failure to solve the problem of sagging of the coating on vertical surfaces. In addition, the wet film thickness threshold of existing anti-sagging microgels is generally low (approximately 125μm), which makes it difficult to adapt to the thick coating requirements of high-solids content coatings, resulting in material waste.

[0004] In view of this, it is necessary to provide a multifunctional acrylic microgel emulsion to solve the deficiencies in the prior art. Summary of the Invention

[0005] The present invention aims to provide a multifunctional acrylic microgel emulsion and its preparation method and application, so as to solve the problems of poor self-repairing and anti-sagging properties of existing acrylic microgel emulsions.

[0006] In a first aspect, the present invention provides a multifunctional acrylic microgel emulsion, comprising a core layer component, a shell layer component, and an auxiliary agent component; wherein, in parts by weight, the core layer component comprises: 10-30 parts of methyl methacrylate, 1-10 parts of butyl methacrylate, 5-15 parts of trimethylolpropane triacrylate, 1-10 parts of a functional monomer, and 15-25 parts of styrene; the shell layer component comprises: 5-15 parts of methyl methacrylate, 15-25 parts of butyl methacrylate, 2-10 parts of glycidyl methacrylate, 2-10 parts of acrylic acid, and 3-15 parts of styrene; and the auxiliary agent component comprises: 10-15 parts of an emulsifier and 5-15 parts of an initiator.

[0007] In the present invention, the inventors have discovered that by selecting specific core layer components and specific shell layer components, the two work synergistically to significantly improve the anti-sagging and self-healing ability of the acrylic microgel emulsion; specifically, the butyl methacrylate and methyl methacrylate monomers in the core layer give the emulsion good flexibility and adhesion; the high glass transition temperature monomers (methyl methacrylate and styrene) in the shell layer provide higher hardness and corrosion resistance; in addition, the functional monomers in the core layer and the glycidyl methacrylate in the shell layer react through chemical bonding to form a dynamic cross-linked network structure, further enhancing the self-healing ability of the acrylic microgel emulsion.

[0008] In some embodiments, the functional monomer includes at least one of 3-mercaptopropionic acid, hydroxymethyl acrylamide, 2-acrylamido-2-methyl-1-propanoic acid, pentaerythritol tetraacrylate, and hydroxypropyl cellulose methacrylate.

[0009] In some embodiments, the emulsifier includes at least one of dodecylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, sodium lauryl sulfate, and n-octadecyl sulfosuccinic acid.

[0010] In some embodiments, the initiator includes at least one of a persulfate initiator, a peroxide initiator, and an azo initiator.

[0011] In some embodiments, the multifunctional acrylic microgel emulsion has a solid content of 30-45%.

[0012] In a second aspect, the present invention provides a method for preparing any of the above-mentioned multifunctional acrylic microgel emulsions, comprising the following steps: S1, dissolving an emulsifier in a first water and an initiator in a second water to obtain an emulsifier solution and an initiator solution, respectively; S2, mixing a core layer component with 1 / 3-1 / 2 of the emulsifier solution to obtain a core layer pre-emulsion; mixing a shell layer component with the remaining emulsifier solution to obtain a shell layer pre-emulsion; S3, mixing the core layer pre-emulsion with 8 / 15-4 / 5 of the initiator solution to obtain a core layer emulsion; S4, mixing the core layer emulsion, the shell layer pre-emulsion, and the remaining initiator solution, reacting the mixture, filtering, and adjusting the pH to 6.5-7.5 to obtain a multifunctional acrylic microgel emulsion.

[0013] In some embodiments, in step S1, the amount of the first water is 40-60 parts by weight, and the amount of the second water is 90-120 parts by weight.

[0014] In some embodiments, in step S3, the core layer pre-emulsion and 8 / 15-4 / 5 initiator solution are mixed to obtain the core layer emulsion, which specifically includes: adding 1 / 3-2 / 3 of the core layer pre-emulsion and 4 / 15-2 / 5 of the initiator solution by a first dropwise addition, performing a first mixing to obtain a first core layer emulsion, and continuing to add the remaining core layer pre-emulsion and 4 / 15-2 / 5 of the initiator solution by a second dropwise addition to the first core layer emulsion, and then performing a second mixing to obtain the core layer emulsion; wherein the temperature of the first mixing is 70~80°C, and the time is 0.5~1h; the temperature of the second mixing is 75~85°C, and the time is 0.5~1h; and the time of the second dropping is 1~1.5h.

[0015] In some embodiments, in step S4, the reaction after mixing the core layer emulsion, the shell layer pre-emulsion and the remaining initiator solution specifically includes: adding the shell layer pre-emulsion and the remaining initiator solution to the core layer emulsion for a third time for third mixing; wherein the temperature of the third mixing is 75~85°C, and the time is 0.5~1h; the time of the third addition is 1~1.5h.

[0016] In some embodiments, in step S4, filtration is performed using 200 mesh nylon cloth, and the solution for adjusting pH includes 5% saturated sodium bicarbonate solution.

[0017] In a third aspect, the present invention provides use of any of the above multifunctional acrylic microgel emulsions or the multifunctional acrylic microgel emulsion prepared by any of the above preparation methods in coatings.

[0018] The beneficial effects of the present invention are as follows: unlike the prior art, the present invention selects specific core layer components and specific shell layer components, and the synergistic effect of the two significantly improves the anti-sagging property and self-healing ability of the acrylic microgel emulsion; specifically, the butyl methacrylate and methyl methacrylate monomers in the core layer impart good flexibility and adhesion to the emulsion; the high glass transition temperature monomers (methyl methacrylate and styrene) in the shell layer provide high hardness and corrosion resistance; in addition, the functional monomers in the core layer react with the glycidyl methacrylate in the shell layer through chemical bonding to form a dynamic cross-linked network structure, further improving the self-healing ability of the acrylic microgel emulsion; therefore, the multifunctional acrylic microgel emulsion has good application prospects in coatings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the structure of the multifunctional acrylic microgel emulsion prepared in Example 3 of the present invention; Figure 2 These are the SEM images before (A) and after (B) repair using the multifunctional acrylic microgel emulsion in the application test example of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0021] For experimental methods in the examples where specific conditions are not specified, generally conventional conditions and conditions described in the manual or conditions recommended by the manufacturer were followed. The general equipment, materials, reagents, etc. used were all commercially available unless otherwise specified.

[0022] Currently, existing acrylic microgel emulsions have problems with poor self-repairing and anti-sagging properties.

[0023] In order to solve the problems of poor self-repairing and anti-sagging properties of existing acrylic microgel emulsions, the present invention provides a multifunctional acrylic microgel emulsion and a preparation method and application thereof.

[0024] In a first aspect, the present invention provides a multifunctional acrylic microgel emulsion, comprising a core layer component, a shell layer component, and an auxiliary agent component; wherein, in parts by weight, the core layer component comprises: 10 to 30 parts of methyl methacrylate, for example, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, or other values within the same range; 1 to 10 parts of butyl methacrylate, for example, 1 part, 3 parts, 5 parts, 7 parts, 10 parts, or other values within the same range; 5 to 15 parts of trimethylolpropane triacrylate, for example, 5 parts, 7 parts, 10 parts, 13 parts, 15 parts, or other values within the same range; 1 to 10 parts of a functional monomer, for example, 1 part, 3 parts, 5 parts, 7 parts, 10 parts, or other values within the same range; 15 to 25 parts of styrene, for example, 15 parts, 17 parts, 20 parts, 23 parts, 25 parts, or other values within the same range; the shell layer component comprises: 5 to 15 parts of methyl methacrylate, for example, For example, it can be 5 parts, 7 parts, 10 parts, 13 parts, 15 parts or other values within this range; butyl methacrylate 15-25 parts, for example, 15 parts, 17 parts, 20 parts, 23 parts, 25 parts or other values within this range; glycidyl methacrylate 2-10 parts, for example, 2 parts, 4 parts, 6 parts, 8 parts, 10 parts or other values within this range; acrylic acid 2-10 parts, for example, 2 parts, 4 parts, 6 parts, 8 parts, 10 parts or other values within this range; styrene 3-15 parts, for example, 3 parts, 5 parts, 7 parts, 10 parts, 13 parts, 15 parts or other values within this range; auxiliary components include: emulsifier 10-15 parts, for example, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts or other values within this range; initiator 5-15 parts, for example, 5 parts, 7 parts, 10 parts, 13 parts, 15 parts or other values within this range.

[0025] In the present invention, the inventors have discovered that by selecting specific core layer components and specific shell layer components, the two work synergistically to significantly improve the anti-sagging and self-healing ability of the acrylic microgel emulsion; specifically, the butyl methacrylate and methyl methacrylate monomers in the core layer give the emulsion good flexibility and adhesion; the high glass transition temperature monomers (methyl methacrylate and styrene) in the shell layer provide higher hardness and corrosion resistance; in addition, the functional monomers in the core layer and the glycidyl methacrylate in the shell layer react through chemical bonding to form a dynamic cross-linked network structure, further enhancing the self-healing ability of the acrylic microgel emulsion.

[0026] In some embodiments, the functional monomer includes at least one of 3-mercaptopropionic acid, hydroxymethyl acrylamide, 2-acrylamido-2-methyl-1-propanoic acid, pentaerythritol tetraacrylate, and hydroxypropyl cellulose methacrylate.

[0027] In the present invention, by selecting specific functional monomers, they react with glycidyl methacrylate in the shell layer through chemical bonding to form a dynamic cross-linked network structure, thereby further improving the self-healing ability of the acrylic microgel emulsion.

[0028] In some embodiments, the emulsifier includes at least one of dodecylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, sodium lauryl sulfate, and n-octadecyl sulfosuccinic acid.

[0029] In the present invention, the composite emulsifier obtained by combining at least two of the following is preferred: dodecylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, sodium lauryl sulfate, and n-octadecyl sulfosuccinic acid. This composite emulsifier can effectively reduce water surface tension, uniformly disperse the monomer in the aqueous phase, form a more stable emulsion system, prevent agglomeration and coagulation of the microgel emulsion during the polymerization process, and improve the controllability of the polymerization reaction.

[0030] In some embodiments, the initiator includes at least one of a persulfate initiator, a peroxide initiator, and an azo initiator.

[0031] It is understandable that persulfate initiators, peroxide initiators and azo initiators can be conventionally selected according to actual use needs. For example, the persulfate initiator can include at least one of ammonium persulfate, potassium persulfate, and sodium persulfate; the peroxide initiator can include at least one of benzoyl peroxide, peracetic acid, and perbenzoic acid; and the azo initiator can include azobisisobutyronitrile.

[0032] In some embodiments, the solid content of the multifunctional acrylic microgel emulsion is 30-45%, for example, 30%, 35%, 40%, 45% or other values within the range.

[0033] The multifunctional acrylic microgel emulsion of the present invention has a good solid content, and therefore, the performance of the acrylic microgel emulsion is good.

[0034] In a second aspect, the present invention provides a method for preparing any of the above-mentioned multifunctional acrylic microgel emulsions, comprising the following steps: S1, dissolving an emulsifier in a first water and an initiator in a second water to obtain an emulsifier solution and an initiator solution, respectively; S2, mixing a core layer component with 1 / 3-1 / 2 of the emulsifier solution to obtain a core layer pre-emulsion; mixing a shell layer component with the remaining emulsifier solution to obtain a shell layer pre-emulsion; S3, mixing the core layer pre-emulsion with 8 / 15-4 / 5 of the initiator solution to obtain a core layer emulsion; S4, mixing the core layer emulsion, the shell layer pre-emulsion, and the remaining initiator solution, reacting the mixture, filtering, and adjusting the pH to 6.5-7.5 to obtain a multifunctional acrylic microgel emulsion.

[0035] The preparation method provided by the present invention is simple, the raw materials used are cheap and easily available, and it is suitable for large-scale production applications; in addition, the reactions are all synthesized in an aqueous system, which reduces the use of organic solvents and is more environmentally friendly.

[0036] In some embodiments, in step S1, the amount of the first water is 40-60 parts by weight, for example, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts or other values within the range; the amount of the second water is 90-120 parts by weight, for example, 90 parts, 100 parts, 110 parts, 120 parts or other values within the range.

[0037] In some embodiments, in step S3, the step of mixing the core layer pre-emulsion and the initiator solution of 8 / 15-4 / 5 to obtain the core layer emulsion specifically comprises: adding 1 / 3-2 / 3 (preferably 1 / 2) of the core layer pre-emulsion and 4 / 15-2 / 5 (preferably 1 / 3) of the initiator solution by a first dropwise addition, performing a first mixing to obtain a first core layer emulsion, continuing to add the remaining core layer pre-emulsion and 4 / 15-2 / 5 (preferably 1 / 3) of the initiator solution by a second dropwise addition to the first core layer emulsion, and performing a second mixing to obtain a core layer emulsion; wherein the temperature of the first mixing is 70-80°C, for example For example, it can be 70°C, 72°C, 75°C, 77°C, 80°C or other values within this range; the time is 0.5~1h, for example, it can be 0.5h, 0.8h, 1h or other values within this range; the temperature of the second mixing is 75~85°C, for example, it can be 75°C, 77°C, 80°C, 83°C, 85°C or other values within this range; the time is 0.5~1h, for example, it can be 0.5h, 0.8h, 1h or other values within this range; the time of the second dropping is 1~1.5h, for example, it can be 1h, 1.2h, 1.5h or other values within this range.

[0038] In the present invention, the performance of the core layer emulsion can be improved by synthesizing the core layer emulsion in steps.

[0039] In some embodiments, in step S4, the reaction after mixing the core layer emulsion, the shell layer pre-emulsion and the remaining initiator solution specifically includes: adding the shell layer pre-emulsion and the remaining initiator solution to the core layer emulsion for a third mixing; wherein the temperature of the third mixing is 75~85℃, for example, it can be 75℃, 77℃, 80℃, 83℃, 85℃ or other values within the range; the time is 0.5~1h, for example, it can be 0.5h, 0.8h, 1h or other values within the range; the time of the third addition is 1~1.5h, for example, it can be 1h, 1.2h, 1.5h or other values within the range.

[0040] In some embodiments, in step S4, filtration is performed using 200 mesh nylon cloth, and the solution for adjusting pH includes 5% saturated sodium bicarbonate solution.

[0041] In a third aspect, the present invention provides use of any of the above multifunctional acrylic microgel emulsions or the multifunctional acrylic microgel emulsion prepared by any of the above preparation methods in coatings.

[0042] In this invention, when a multifunctional acrylic microgel emulsion is added at a 15% dosage to a water-based epoxy resin coating, the coating exhibits no sagging at a wet film thickness of 240 μm, as tested according to the GB / T 9264-2012 standard. This represents a 92% improvement over the 125 μm threshold for conventional anti-sag microgels. In coating experiments on walls with complex surfaces (such as corners and surrounding decorative elements), coating thickness uniformity was improved by 40%, effectively preventing material loss caused by localized sagging, reducing costs, and protecting the wall surface from corrosion.

[0043] Furthermore, self-healing tests of this multifunctional acrylic microgel emulsion revealed a scratch repair rate of 97% (50μm depth) after treatment at 90°C for 1 hour. The repaired coating achieved a hardness of 6H (GB / T 6739-2022), 1800h of water immersion resistance, and 1200h of salt spray resistance, significantly improving corrosion resistance compared to traditional microgel coatings. Furthermore, increasing the repair temperature to 90°C prevents surface heating caused by direct sunlight, while maintaining the coating's softening properties. The coating's rigidity (Tg = 105°C) and thermal stability are significantly enhanced.

[0044] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0045] Example 1 A multifunctional acrylic microgel emulsion, comprising a core layer component, a shell layer component, and an auxiliary agent component; The core layer components include, by weight: 20 parts of methyl methacrylate, 5 parts of butyl methacrylate, 5 parts of trimethylolpropane triacrylate, 2 parts of 3-mercaptopropionic acid, and 15 parts of styrene; The shell layer components include: 8 parts of methyl methacrylate, 15 parts of butyl methacrylate, 3 parts of glycidyl methacrylate, 2 parts of acrylic acid, and 6 parts of styrene; The auxiliary agent component includes: 10 parts of a mixture of dodecylphenol polyoxyethylene ether and sodium dodecylbenzene sulfonate in a mass ratio of 2:1, and 5 parts of potassium persulfate.

[0046] The preparation method of the multifunctional acrylic microgel emulsion comprises the following steps: S1, dissolving an emulsifier in 50 parts of the first water and an initiator in 100 parts of the second water to obtain an emulsifier solution and an initiator solution, respectively; S2. Slowly drop the core layer component into 1 / 3 of the emulsifier solution while stirring, fully stirring at room temperature, and pre-emulsifying for 0.5 h to obtain a core layer pre-emulsion; slowly drop the shell layer component into the remaining emulsifier solution while stirring, fully stirring at room temperature, and pre-emulsifying for 0.5 h to obtain a shell layer pre-emulsion; S3. In a four-necked flask equipped with a stirring paddle, a condenser, and a dropping funnel, purging with Ar gas to remove air, add 1 / 2 of the core layer pre-emulsion and 1 / 3 of the initiator solution dropwise for the first time at 75°C until a large amount of blue light appears in the emulsion, and keep the temperature for 0.5h to obtain a first core layer emulsion. Continue to add the remaining core layer pre-emulsion and 1 / 3 of the initiator solution dropwise to the first core layer emulsion for the second time (addition completed within 1h), and keep the temperature at 80°C for 0.5h to obtain a core layer emulsion. S4. After adding the shell pre-emulsion and the remaining initiator solution to the core layer emulsion for the third time (the addition is completed within 1.5 hours), the temperature is kept at 85°C for 0.5 hours, and then naturally cooled to 40°C. The mixture is filtered through a 200-mesh nylon cloth, and a 5% saturated sodium bicarbonate solution is added to adjust the pH to 7.0 to obtain a multifunctional acrylic microgel emulsion.

[0047] In this embodiment, the multifunctional acrylic microgel emulsion has a solid content of 36%, a particle size of 382 nm, and a cross-linking self-repair time of approximately 90 minutes at 90°C. After repair, the scratches on the surface of the paint film basically disappear. The hardness of the repaired coating is 4H, and it is resistant to hot water soaking for 1000 hours and salt spray for 700 hours. No sagging occurs when the film thickness is 200 μm.

[0048] Example 2 A multifunctional acrylic microgel emulsion, comprising a core layer component, a shell layer component, and an auxiliary agent component; The core layer components include, by weight: 10 parts of methyl methacrylate, 3 parts of butyl methacrylate, 8 parts of trimethylolpropane triacrylate, 6 parts of 3-mercaptopropionic acid, and 15 parts of styrene; The shell layer components include: 10 parts of methyl methacrylate, 15 parts of butyl methacrylate, 3 parts of glycidyl methacrylate, 2 parts of acrylic acid, and 4 parts of styrene; The auxiliary agent component includes: 12 parts of a mixture of dodecylphenol polyoxyethylene ether and sodium dodecylbenzene sulfonate in a mass ratio of 2:1, and 6 parts of potassium persulfate.

[0049] The preparation method of the multifunctional acrylic microgel emulsion comprises the following steps: S1, dissolving an emulsifier in 50 parts of the first water and an initiator in 100 parts of the second water to obtain an emulsifier solution and an initiator solution, respectively; S2. Slowly drop the core layer component into 1 / 3 of the emulsifier solution while stirring, fully stirring at room temperature, and pre-emulsifying for 1 hour to obtain a core layer pre-emulsion; slowly drop the shell layer component into the remaining emulsifier solution while stirring, fully stirring at room temperature, and pre-emulsifying for 1 hour to obtain a shell layer pre-emulsion; S3. In a four-necked flask equipped with a stirring paddle, a condenser, and a dropping funnel, purging with Ar gas to remove air, add 1 / 2 of the core layer pre-emulsion and 1 / 3 of the initiator solution dropwise for the first time at 75°C until a large amount of blue light appears in the emulsion, and keep the temperature for 0.5 h to obtain a first core layer emulsion. Continue to add the remaining core layer pre-emulsion and 1 / 3 of the initiator solution dropwise to the first core layer emulsion for the second time (the addition is completed within 1.5 h), and keep the temperature at 80°C for 0.5 h to obtain a core layer emulsion. S4. After adding the shell pre-emulsion and the remaining initiator solution to the core layer emulsion for the third time (the addition is completed within 1.5 hours), the temperature is kept at 85°C for 0.5 hours, and then naturally cooled to 40°C. The mixture is filtered through a 200-mesh nylon cloth, and a 5% saturated sodium bicarbonate solution is added to adjust the pH to 7.0 to obtain a multifunctional acrylic microgel emulsion.

[0050] In this embodiment, the multifunctional acrylic microgel emulsion has a solid content of 38%, a particle size of 475 nm, and a cross-linking self-repair time of approximately 60 minutes at 90°C. After repair, scratches on the surface of the paint film are significantly lighter. The repaired coating has a hardness of 5H, is resistant to hot water soaks for 1000 hours, and is resistant to salt spray for 600 hours. No sagging occurs when the film thickness is 220 μm.

[0051] Example 3 A multifunctional acrylic microgel emulsion, comprising a core layer component, a shell layer component, and an auxiliary agent component; The core layer components include, by weight: 10 parts of methyl methacrylate, 5 parts of butyl methacrylate, 8 parts of trimethylolpropane triacrylate, 5 parts of 3-mercaptopropionic acid, and 15 parts of styrene; The shell layer components include: 10 parts of methyl methacrylate, 15 parts of butyl methacrylate, 5 parts of glycidyl methacrylate, 2 parts of acrylic acid, and 6 parts of styrene; The auxiliary agent component includes: 12 parts of a mixture of dodecylphenol polyoxyethylene ether and sodium dodecylbenzene sulfonate in a mass ratio of 2:1, and 6 parts of potassium persulfate.

[0052] The preparation method of the multifunctional acrylic microgel emulsion comprises the following steps: S1, dissolving an emulsifier in 40 parts of the first water and an initiator in 120 parts of the second water to obtain an emulsifier solution and an initiator solution, respectively; S2. Slowly drop the core layer component into 1 / 2 of the emulsifier solution while stirring, fully stirring at room temperature, and pre-emulsifying for 1 hour to obtain a core layer pre-emulsion; slowly drop the shell layer component into the remaining emulsifier solution while stirring, fully stirring at room temperature, and pre-emulsifying for 1 hour to obtain a shell layer pre-emulsion; S3. In a four-necked flask equipped with a stirring paddle, a condenser, and a dropping funnel, purging with Ar gas to remove air, add 1 / 2 of the core layer pre-emulsion and 1 / 3 of the initiator solution dropwise for the first time at 75°C until a large amount of blue light appears in the emulsion, thereby obtaining a first core layer emulsion. Continuously add the remaining core layer pre-emulsion and 1 / 3 of the initiator solution dropwise for the second time (addition to be completed within 1 hour) to the first core layer emulsion, and then keep the temperature at 80°C for 40 minutes to obtain a core layer emulsion. S4. After adding the shell pre-emulsion and the remaining initiator solution to the core layer emulsion for the third time (the addition is completed within 1.5 hours), the temperature is kept at 85°C for 40 minutes, and then naturally cooled to 40°C. The mixture is filtered through a 200-mesh nylon cloth, and a 5% saturated sodium bicarbonate solution is added to adjust the pH to 7.0 to obtain a multifunctional acrylic microgel emulsion.

[0053] In this embodiment, the multifunctional acrylic microgel emulsion has a solid content of 42%, a particle size of 273 nm, and a cross-linking self-repair time of approximately 45 minutes at 90°C. After repair, virtually no scratches are observed on the surface of the paint film. The repaired coating has a hardness of 6H, is resistant to hot water soaks for 1800 hours, and is resistant to salt spray for 1200 hours. No sagging occurs when the film thickness is 240 μm.

[0054] Comparative Example 1 In this comparative example, the components and preparation method of the multifunctional acrylic microgel emulsion are basically the same as those in Example 3, except that the core layer component contains 2 parts of 3-mercaptopropionic acid and the shell layer component contains 5 parts of glycidyl methacrylate.

[0055] In this comparative example, a multifunctional acrylic microgel emulsion with a solids content of 40% and a particle size of 345 nm exhibited no self-repairing properties at 90°C, even after extended repair time. The results indicate that reducing the contents of 3-mercaptopropionic acid and glycidyl methacrylate destabilizes the dynamic crosslinking network and reduces the self-repairing ability of the acrylic microgel emulsion.

[0056] Comparative Example 2 In this comparative example, the components and preparation method of the multifunctional acrylic microgel emulsion are basically the same as those in Example 3, except that the amount of methyl methacrylate in the shell component is 8 parts, and the amount of toluene vinyl in the shell component is 3 parts.

[0057] In this comparative example, the multifunctional acrylic microgel emulsion has a solid content of 42%, a particle size of 182 nm, and a cross-linking self-repair time of about 60 min at 90°C. Basically, no scratches are observed on the surface of the paint film after repair, but softening of the coating surface is observed at 40 min, and part of the coating falls off. The hardness of the repaired coating is 2H, and it is resistant to hot water soaking for 500 h and salt spray for 300 h. There is obvious sagging when the film thickness is 180 μm. The results show that the sagging performance, hardness and corrosion resistance of the acrylic microgel emulsion are related to the content of methyl methacrylate and styrene in the shell component.

[0058] Application test case Currently, building exterior walls are exposed to the elements for long periods of time, affected by ultraviolet rays, acid rain, and other factors, making them prone to micro-cracks, peeling, and fading. These damages not only affect the building's aesthetics but can also lead to problems such as water infiltration and structural corrosion, increasing maintenance costs.

[0059] Therefore, the present invention provides an exterior wall coating with self-repairing function, specifically, the acrylic microgel emulsion prepared in Example 3 of the present invention (schematic diagram as shown in FIG. Figure 1 The emulsion (shown as an additive amount of 15% of the total coating weight) was added to a waterborne epoxy resin coating. Once the emulsion was evenly dispersed throughout the coating, testing according to the GB / T 9264-2012 standard revealed no sagging at a wet film thickness of 240μm, a 92% improvement over the 125μm threshold for traditional anti-sag microgels. In coating experiments on walls with complex surfaces (such as corners and surrounding decorative elements), coating thickness uniformity was improved by 40%, effectively preventing material loss caused by localized sagging, reducing costs, and protecting the wall surface from corrosion.

[0060] Furthermore, the multifunctional acrylic microgel emulsion prepared in Example 3 was subjected to a self-repair test. Figure 2 (A) shows that after repair, Figure 2 (B) After treatment at 90°C for 1 hour, the scratch repair rate (50μm depth) reached 97%. The repaired coating achieved a hardness of 6H (GB / T 6739-2022), 1800 hours of water immersion resistance, and 1200 hours of salt spray resistance, significantly improving its corrosion resistance compared to traditional microgel coatings. Furthermore, increasing the repair temperature to 90°C prevents repair errors caused by surface heating from direct sunlight, while maintaining high temperatures without softening the coating. This significantly enhances the coating's rigidity (Tg = 105°C) and thermal stability.

[0061] Therefore, adding the acrylic microgel emulsion of the present invention to water-based paint can significantly improve the sag property of the paint film, and at the same time has a certain self-repairing ability, which can effectively extend the service life of the building exterior wall and reduce the maintenance frequency and cost.

[0062] It should be noted that the above embodiments all belong to the same inventive concept, and the description of each embodiment has its own focus. For any details not described in individual embodiments, reference may be made to the description in other embodiments.

[0063] The above-described embodiments merely illustrate the implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A multifunctional acrylic microgel emulsion, characterized in that: Including core layer components, shell layer components, and auxiliary agent components; Wherein, the core layer components include, by weight: 10-30 parts of methyl methacrylate, 1-10 parts of butyl methacrylate, 5-15 parts of trimethylolpropane triacrylate, 1-10 parts of functional monomer, and 15-25 parts of styrene; The shell layer components include: 5-15 parts of methyl methacrylate, 15-25 parts of butyl methacrylate, 2-10 parts of glycidyl methacrylate, 2-10 parts of acrylic acid, and 3-15 parts of styrene; The auxiliary agent components include: 10-15 parts of emulsifier and 5-15 parts of initiator.

2. The multifunctional acrylic microgel emulsion according to claim 1, characterized in that The functional monomer includes at least one of 3-mercaptopropionic acid, hydroxymethyl acrylamide, 2-acrylamido-2-methyl-1-propanoic acid, pentaerythritol tetraacrylate, and hydroxypropyl cellulose methacrylate.

3. The multifunctional acrylic microgel emulsion according to claim 1, characterized in that: The emulsifier includes at least one of dodecylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, sodium lauryl sulfate, and n-octadecyl sulfosuccinic acid.

4. The multifunctional acrylic microgel emulsion according to claim 1, characterized in that The initiator includes at least one of a persulfate initiator, a peroxide initiator and an azo initiator.

5. The multifunctional acrylic microgel emulsion according to claim 1, characterized in that: The solid content of the multifunctional acrylic microgel emulsion is 30-45%.

6. The method for preparing the multifunctional acrylic microgel emulsion according to any one of claims 1 to 5, characterized in that: The steps include: S1, dissolving an emulsifier in a first water and an initiator in a second water to obtain an emulsifier solution and an initiator solution, respectively; S2, mixing the core layer component and 1 / 3-1 / 2 of the emulsifier solution to obtain a core layer pre-emulsion; mixing the shell layer component and the remaining emulsifier solution to obtain a shell layer pre-emulsion; S3, mixing the core layer pre-emulsion and the initiator solution in a ratio of 8 / 15-4 / 5 to obtain a core layer emulsion; S4, mixing the core layer emulsion, the shell layer pre-emulsion and the remaining initiator solution, reacting the mixture, filtering and adjusting the pH to 6.5-7.5 to obtain a multifunctional acrylic microgel emulsion.

7. The method for preparing the multifunctional acrylic microgel emulsion according to claim 6, wherein: In step S1, the amount of the first water is 40-60 parts by weight, and the amount of the second water is 90-120 parts by weight.

8. The method for preparing the multifunctional acrylic microgel emulsion according to claim 6, wherein: In step S3, the step of mixing the core layer pre-emulsion and 8 / 15-4 / 5 of the initiator solution to obtain the core layer emulsion specifically comprises: first adding 1 / 3-2 / 3 of the core layer pre-emulsion and 4 / 15-2 / 5 of the initiator solution dropwise, followed by first mixing to obtain a first core layer emulsion; and continuing to add the remaining core layer pre-emulsion and 4 / 15-2 / 5 of the initiator solution dropwise to the first core layer emulsion, followed by second mixing to obtain a core layer emulsion; The temperature of the first mixing is 70-80° C., and the time is 0.5-1 h; the temperature of the second mixing is 75-85° C., and the time is 0.5-1 h; and the time of the second dropping is 1-1.5 h.

9. The method for preparing the multifunctional acrylic microgel emulsion according to claim 6, wherein: In step S4, the reaction after mixing the core layer emulsion, the shell layer pre-emulsion and the remaining initiator solution specifically includes: adding the shell layer pre-emulsion and the remaining initiator solution to the core layer emulsion by a third dropwise process for a third mixing; The temperature of the third mixing is 75-85° C., and the time is 0.5-1 h; and the time of the third dropping is 1-1.5 h.

10. Use of the multifunctional acrylic microgel emulsion according to any one of claims 1 to 5 or the multifunctional acrylic microgel emulsion prepared by the preparation method according to any one of claims 6 to 9 in coatings.

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