High-weatherability stone-imitating real stone paint and preparation method thereof

Abstract

The application discloses a kind of high weatherability stone-like stone paint and preparation method thereof, relate to building exterior wall decorative coating technical field, the stone paint is mainly by fluorine silicon super weatherability core-shell emulsion, interface strengthening type self-repairing microcapsule, multifunctional reactive additive complex package, graded natural color sand and water, pH adjusting agent, antifreezing agent, film forming aid, thickening agent Composition, the shell layer of fluorine silicon super weatherability core-shell emulsion contains the co-continuous network structure formed by fluorocarbon chain segment and polysiloxane chain segment, interface strengthening type self-repairing microcapsule surface is grafted and modified by silane coupling agent, and double bond functional group is introduced, during film forming process, each reactive component is formed by free radical copolymerization three-dimensional network structure connected by covalent bond, when the coating of the application produces micro crack, microcapsule can respond to pH change and release repair agent, spontaneously restore coating waterproof performance, while coating has excellent weather resistance, dirt resistance, mechanical strength and flame-retardant thermal insulation performance, can satisfy the long-term protection demand of building exterior wall under complex climate.

Description

Technical Field

[0001] This invention relates to the field of building exterior wall decorative coatings, specifically to a high weather-resistant imitation stone paint and its preparation method. Background Technology

[0002] Imitation stone paint uses natural colored sand as aggregate and synthetic resin emulsion as film-forming substance. It has the advantages of realistic texture, simple construction and controllable cost, and has become one of the mainstream materials for building exterior wall decoration, especially in high-rise buildings and complex climatic environments.

[0003] Existing technologies have improved the weather resistance and waterproofing of stone-like paint. For example, invention patent publication number CN117487424B discloses a high weather-resistant and anti-pollution stone-like paint, which uses a water-based fluorocarbon emulsion and a silicone-acrylic emulsion for physical blending, while adding fluorocarbon-coated hydrotalcite and modified lignin to enhance the coating's weather resistance and anti-pollution ability. However, in this scheme, no chemical bond is formed between the two emulsions, resulting in microscopic phase separation, allowing moisture to preferentially penetrate from the weak interface during long-term service. Another existing invention patent publication number CN120424541A discloses a water-based environmentally friendly emulsion and its application in stone-like paint coatings. This involves grafting and modifying sodium alginate microcapsules coated with bisphenol A epoxy resin and blending them with a styrene-acrylic emulsion to give the coating a certain self-healing ability. However, in this scheme, the microcapsules and emulsion are only physically interlocked; the microcapsules are prone to rupture or agglomeration during high-shear stirring and storage, leading to premature leakage of the repair agent and preventing precise triggering and effective repair when the coating is damaged.

[0004] The aforementioned existing technologies each address problems at different levels, but none of them solve a problem inherent in the actual service life of stone-like paint coatings: once microcracks appear in the coating due to thermal expansion and contraction or external forces, the waterproof function immediately fails, and existing solutions cannot enable the coating to spontaneously recover its waterproof performance after damage. If fluorocarbon emulsions are simply physically mixed with self-healing microcapsules, the lack of chemical anchoring between the microcapsules and the emulsion substrate results in insufficient interfacial bonding, which actually exacerbates the deterioration of the coating's mechanical properties and the reduction of its waterproof function, further shortening the coating's lifespan.

[0005] Those skilled in the art have long faced the aforementioned technical dilemmas and urgently need to develop a long-lasting, highly weather-resistant imitation stone paint that can spontaneously repair its waterproof function after coating damage. Therefore, this invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a high weather-resistant imitation stone paint and its preparation method. By covalently cross-linking a fluorosilicone ultra-weather-resistant core-shell emulsion, an interface-enhanced self-healing microcapsule, and a multifunctional reactive additive to form a three-dimensional network structure, the interfacial bonding between the components is strengthened, and the pH-responsive self-healing of microcracks in the coating is achieved. This simultaneously improves the coating's weather resistance, waterproofing, and mechanical properties, thus overcoming the shortcomings of existing imitation stone paints, such as easy failure of waterproofing function and short service life after damage.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A high weather-resistant imitation stone paint, comprising the following components in parts by weight:

[0008] Fluorosilicone ultra-weather-resistant core-shell emulsion, 180–300 parts;

[0009] Interface-enhanced self-healing microcapsules, 15-50 parts;

[0010] Multifunctional reactive adjuvant compound package, 5-20 parts;

[0011] Graded natural colored sand, 600-750 parts;

[0012] Deionized water, 40-80 parts;

[0013] pH adjuster, 1-3 parts;

[0014] Antifreeze, 5-15 parts;

[0015] Film-forming aid, 8-20 parts;

[0016] Thickener, 2-6 parts;

[0017] The fluorosilicone ultra-weather-resistant core-shell emulsion provides an ultra-low surface energy waterproof framework. The interface-reinforced self-healing microcapsules release a repair agent in response to pH changes when the coating is damaged. The fluorosilicone ultra-weather-resistant core-shell emulsion has a core layer and a shell layer. The shell layer contains a co-continuous network structure formed by fluorocarbon segments and polysiloxane segments. The shell layer also contains reactive groups.

[0018] The interface-enhanced self-healing microcapsules have a pH-responsive wall material, and the surface of the wall material is modified by grafting a polymerizable silane coupling agent to introduce double bond functional groups.

[0019] The multifunctional reactive additive composite contains at least one polymerizable functional group;

[0020] The double-bonded functional groups of the interface-enhanced self-healing microcapsules, the reactive groups of the fluorosilicone ultra-weather-resistant core-shell emulsion, and the polymerizable functional groups of the multifunctional reactive additive composite package form a three-dimensional network structure with covalent bonds through free radical copolymerization during the film formation process.

[0021] Furthermore, the fluorosilicone ultra-weather-resistant core-shell emulsion is prepared by a two-step seed pre-emulsification core-shell polymerization process using core layer monomers and shell layer monomers. The core layer monomers contain 40-65 parts by weight of methyl methacrylate, 20-40 parts by weight of butyl acrylate, 2-6 parts by weight of methacrylic acid, and 1-6 parts by weight of crosslinking monomers. The shell layer monomers contain 15-30 parts by weight of fluorinated monomers, 10-25 parts by weight of silicon-containing monomers, 2-5 parts by weight of polymerizable hindered amine light stabilizers, and 2-5 parts by weight of reactive phosphorus-containing flame-retardant monomers. The core layer provides high crosslinking hardness and adhesion, while the fluorosilicone co-continuous network in the shell layer imparts ultra-weather resistance and water resistance to the coating.

[0022] Furthermore, the interface-reinforced self-healing microcapsules are formed through in-situ polymerization, using melamine-formaldehyde resin, polyurea, or polyurethane as wall material raw materials. The polymerizable silane coupling agent is γ-methacryloyloxypropyltrimethoxysilane. The particle size of the interface-reinforced self-healing microcapsules is 2–20 μm, the repair agent encapsulation rate is above 85%, and the pH response trigger threshold is pH 4.0–6.0. ​​The microcapsule wall material swells and ruptures in an acidic environment, allowing the repair agent to fill the microcracks in the coating and re-solidify to seal the damaged area.

[0023] Furthermore, the multifunctional reactive additive composite package comprises: 1-4 parts by weight of polymerizable HALS hindered amine light stabilizer, 1-4 parts by weight of methacryloyloxyethyl phosphate, 1-3 parts by weight of polymerizable silane coupling agent, 0.5-2 parts by weight of reactive fluorinated surfactant, 1-5 parts by weight of nano-antimony-doped tin oxide dispersion, and 0.5-4 parts by weight of nano-antimony-doped tin oxide and indium tin oxide composite infrared reflective paste. The polymerizable functional groups in the additive composite package simultaneously undergo covalent bonding with the fluorosilicone core-shell emulsion and microcapsules to form a molecularly bridged three-dimensional network.

[0024] Furthermore, the graded natural colored sand is 20-120 mesh natural colored sand, and by mass ratio, 40 mesh natural colored sand accounts for 15-25%, 60-80 mesh natural colored sand accounts for 50-60%, and 100-120 mesh natural colored sand accounts for 20-30%. The graded natural colored sand is pre-treated with a dilute solution of silane coupling agent. The moisture content of the treated graded natural colored sand is ≤0.2%. The silane coupling agent treatment enhances the interfacial bonding strength between the colored sand and the fluorosilicone core-shell emulsion and prevents moisture from penetrating along the colored sand interface.

[0025] Furthermore, the antifreeze is propylene glycol or ethylene glycol, the film-forming aid is dodecyl alcohol ester or dipropylene glycol butyl ether, and the thickener is an alkali-swelling thickener or a polyurethane thickener. The above-mentioned aids ensure that the coating forms a complete film and has stable viscosity to support high content of colored sand during low-temperature construction.

[0026] On the other hand, a method for preparing a high weather-resistant imitation stone paint, applicable to a high weather-resistant imitation stone paint, includes the following steps:

[0027] Step 1: Mix graded natural colored sand according to the gradation ratio, spray with a dilute solution of silane coupling agent and stir for 15-20 minutes, then dry at 100-105℃ for 2-4 hours until the moisture content is ≤0.2% to obtain pretreated colored sand;

[0028] Step 2: Add deionized water, antifreeze, film-forming aid and pH adjuster to the dispersion vessel in sequence, stir for 5-10 minutes to obtain the first mixed system;

[0029] Step 3: Add each component of the multifunctional reactive additive composite package to the first mixing system in sequence, and stir at 400-600 rpm for 10-15 min to obtain the second mixing system;

[0030] Step 4: Disperse the interface-enhanced self-healing microcapsules in deionized water at a mass ratio of microcapsules to water of 1:2, and disperse with ultrasonic assistance for 5-10 minutes to form a microcapsule suspension. Add the microcapsule suspension to the second mixing system and stir at 300-500 r / min for 10-15 minutes to obtain the third mixing system.

[0031] Step 5: Add fluorosilicone ultra-weather-resistant core-shell emulsion to the third mixing system and stir at 200-400 r / min for 10-20 min to obtain the fourth mixing system;

[0032] Step 6: Add the pretreated colored sand prepared in Step 1 to the fourth mixing system in batches, stirring for 1-2 minutes after each addition to obtain the fifth mixing system;

[0033] Step 7: Add thickener to the fifth mixing system, adjust the coating viscosity to 90-110 KU, filter with a 40-mesh stainless steel sieve, and package to obtain high weather-resistant imitation stone paint. This method uses low-speed stirring to add microcapsules and colored sand to avoid high shear damage to the integrity of microcapsules and ensure that the three-dimensional network structure exists stably before film formation.

[0034] Furthermore, the fluorosilicone ultra-weather-resistant core-shell emulsion is prepared using the following steps:

[0035] Step 1: Mix 5-10% of the total amount of core layer monomers, composite emulsifier and part of deionized water for pre-emulsification, add initiator, heat to 78-82℃ and react for 30-45 minutes to generate seed emulsion;

[0036] Step 2: The remaining core layer monomer pre-emulsion is added dropwise to the seed emulsion at a uniform rate over 2-3 hours, while maintaining the temperature at 78-82°C. After the addition is completed, the temperature is maintained for 1 hour to obtain the core layer emulsion.

[0037] Step 3: Cool down to 70-75℃, and add the shell monomer pre-emulsion to the core emulsion at a uniform rate over 2-3 hours, while simultaneously adding the initiator. After the addition is complete, raise the temperature to 80-85℃ and keep it at that temperature for 2 hours to obtain the polymerization product.

[0038] Step four: Cool the polymerized product to below 40°C, adjust the pH to 7.5-8.5 with ammonia or organic amine, filter and discharge to obtain a fluorosilicone ultra-weather-resistant core-shell emulsion. The process of polymerizing the core layer first and then the shell layer enriches the fluorosilicone segments on the outer layer of the latex particles, forming a low surface energy protective shell.

[0039] Furthermore, the interface-enhanced self-healing microcapsules are prepared using the following steps:

[0040] Step 1: Take 100 parts by weight of bisphenol A type epoxy resin, 10-20 parts by weight of reactive diluent, and 2-5 parts by weight of catalyst and stir evenly. Add 5-15 parts by weight of modified silicone oil that has been vacuum dried and stir at 50-60℃ for 1 hour to form an oil phase.

[0041] Step 2: Take 300-500 parts by weight of deionized water, add 2-5 parts by weight of a composite emulsifier consisting of sodium salt of styrene-maleic anhydride and sodium dodecyl sulfate in a mass ratio of 2:1, and 1-3 parts by weight of polyvinyl alcohol, stir to dissolve, and adjust the pH to 4.0-5.0 to form an aqueous phase;

[0042] Step 3: Prepare a solution of melamine and formaldehyde by mixing melamine and formaldehyde at a molar ratio of 1:3 and reacting at pH 8.0–9.0 and 70°C for 30 minutes to obtain a melamine-formaldehyde prepolymer solution.

[0043] Step 4: Add the oil phase to the aqueous phase and perform high-speed shear emulsification at a speed of 8000-12000 r / min for 10-20 min to form a stable oil-in-water emulsion.

[0044] Step 5: Add the melamine-formaldehyde prepolymer solution dropwise to the oil-in-water stabilized emulsion, adjust the pH to 3.5-4.5 with formic acid, and react at 60-70°C for 2-4 hours. The wall material is polymerized in situ and coated onto the surface of the oil phase to obtain a microcapsule suspension.

[0045] Step 6: Cool the microcapsule suspension to 40°C, add γ-methacryloxypropyltrimethoxysilane, the amount of γ-methacryloxypropyltrimethoxysilane being 3-8% of the solid content of the microcapsules, adjust the pH to 4.0-5.0 with acetic acid, and stir at 40-50°C for 1-2 hours to graft γ-methacryloxypropyltrimethoxysilane onto the surface of the microcapsule wall material to obtain grafted modified microcapsules;

[0046] Step 7: The grafted modified microcapsules are separated by centrifugation or filtration, washed three times alternately with deionized water and anhydrous ethanol, and vacuum dried at 40-50°C for 12 hours to obtain interface-enhanced self-healing microcapsules. KH570 grafting gives the microcapsule shell polymerizable double bonds, providing reaction sites for subsequent covalent cross-linking with fluorosilicone emulsion.

[0047] Furthermore, the mass ratio of the core layer to the shell layer in the fluorosilicone ultra-weather-resistant core-shell emulsion is 40:60 to 55:45. The fluorine content in the shell layer is 8wt% to 15wt%, the silicon content is 3wt% to 8wt%, the solid content of the fluorosilicone ultra-weather-resistant core-shell emulsion is 45% to 50%, and the latex particle size is 120 to 250 nm. This ratio range ensures that the fluorosilicone segments are fully distributed on the outer layer of the latex particles, while also guaranteeing the storage stability of the emulsion and the mechanical balance after film formation.

[0048] Compared with existing technologies, this high weather-resistant imitation stone paint and its preparation method have the following beneficial effects:

[0049] I. This invention combines interface-enhanced self-healing microcapsules, fluorosilicone ultra-weather-resistant core-shell emulsion, and multifunctional reactive additives in a composite package. During film formation, a three-dimensional network structure with covalent bonds is formed through free radical copolymerization, which strengthens the interfacial bonding between the microcapsules and the emulsion matrix. This prevents the microcapsules from agglomerating, the wall material from cracking, or the repair agent from leaking prematurely during production, stirring, and storage. When the coating develops microcracks due to thermal expansion and contraction or external forces, the microcapsules can release the internal repair agent in response to pH changes in the penetrating medium, filling the cracks and gradually solidifying and sealing the damaged area, spontaneously restoring the waterproof function of the coating. At the same time, it improves the overall mechanical strength of the coating and extends the actual service life of the exterior wall coating.

[0050] II. This invention utilizes a core-shell structured fluorosilicone ultra-weather-resistant emulsion as the film-forming matrix, enriching fluorocarbon and polysiloxane segments on the outer layer of latex particles. After film formation, a low surface energy protective layer is created on the coating surface, effectively improving the coating's weather resistance, stain resistance, and water resistance. Polymerizable light-stabilizing, flame-retardant, and infrared-reflecting functional components are covalently integrated into the coating network, avoiding the problem of easy migration and precipitation of ordinary small-molecule additives. This maintains the coating's aging resistance, flame retardancy, and heat insulation effects for a long time. The graded colored sand pretreated with a silane coupling agent is tightly bonded to the matrix, further blocking the water penetration path and ensuring the stability of the coating during long-term use.

[0051] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0053] Figure 1 This is a schematic diagram of the two-step seed pre-emulsification core-shell polymerization process for the fluorosilicone ultra-weather-resistant core-shell emulsion of the present invention.

[0054] Figure 2 This is a schematic diagram of the structure of the interface-enhanced self-healing microcapsule of the present invention;

[0055] Figure 3 This is a schematic diagram of the three-dimensional cross-linked network structure of the real stone paint after film formation and curing according to the present invention. Detailed Implementation

[0056] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0057] This specific embodiment details a high-weather-resistant imitation stone paint and its preparation method. The technical solution involved can be applied to the field of building exterior wall decoration and protection, taking into account multiple properties such as waterproofing, fireproofing, heat insulation, and infrared stealth compatibility. The following description, in conjunction with the accompanying drawings and embodiments, further elaborates on this solution.

[0058] like Figure 1 As shown, the overall process is divided into four stages: seed emulsion preparation, core-layer polymerization, shell-layer polymerization, and post-processing. Figure 2 As shown, the microcapsule consists of a repair agent core material, a pH-responsive wall material, and a silane coupling agent grafted modification layer from the inside out. The surface of the modification layer contains polymerizable double-bond functional groups. Figure 3 As shown, the fluorosilicone emulsion matrix, microcapsule wall material, and reactive additives are interconnected by covalent bonds, and the natural colored sand is tightly bonded to the matrix through interface treatment.

[0059] This embodiment is a preferred implementation method, which fully presents the entire preparation process of high weather-resistant imitation stone paint, covering all aspects of formula components, intermediate preparation and finished product processing, and verifies the feasibility and comprehensive performance of the solution.

[0060] The preparation of the fluorosilicone ultra-weather-resistant core-shell emulsion is as follows: In this embodiment, a two-step seed pre-emulsification core-shell polymerization process is used to prepare the fluorosilicone ultra-weather-resistant core-shell emulsion. By first polymerizing the hard core and then polymerizing the functional shell, the fluorocarbon segments and polysiloxane segments are enriched on the outer layer of the latex particles. After film formation, a co-continuous low surface energy network can be formed on the coating surface.

[0061] The first step is to prepare the seed emulsion: Weigh 8% of the total core-shell monomer mixture, add a composite emulsifier and some deionized water to the reactor, and stir for pre-emulsification for 15 minutes. The composite emulsifier is a mixture of sodium dodecyl sulfate and fatty alcohol polyoxyethylene ether at a mass ratio of 1:1, with a total amount of 2.5% of the total monomer mass. Add ammonium persulfate as an initiator to the pre-emulsion, with an amount of 0.3% of the total monomer mass. After stirring evenly, heat to 80℃ and maintain the temperature for 35 minutes to generate a stable seed emulsion. The seed emulsion provides uniform polymerization sites, ensuring uniform particle size of the subsequent core-shell particles.

[0062] The second step involves core-layer polymerization: the remaining core-layer monomers are mixed with the corresponding proportions of emulsifier and deionized water, and a core-layer pre-emulsion is prepared by high-speed shearing. The core-layer pre-emulsion is then added dropwise to the seed emulsion at a uniform rate over 2.5 hours, maintaining the reaction temperature at 78–82°C and the stirring speed at 200 rpm. After the addition is complete, the mixture is kept at this temperature for another 1 hour to obtain the core-layer emulsion. The total mass of the core-layer monomers in this step is 200 g, including 110 g of methyl methacrylate, 70 g of butyl acrylate, 12 g of methacrylic acid, and 8 g of the crosslinking monomer diethylene glycol diacrylate. The core-layer monomers are mainly hard monomers, combined with an appropriate amount of crosslinking monomers, which provides sufficient coating hardness and substrate adhesion after film formation, preventing the coating from softening and attracting dust.

[0063] The third step involves shell polymerization: the reaction system is cooled to 70–75°C, and the shell pre-emulsion is added dropwise. The shell pre-emulsion is prepared by pre-emulsification of fluorinated monomers, silicon-containing monomers, polymerizable hindered amine light stabilizers, reactive phosphorus-containing flame retardant monomers and corresponding emulsifiers, and deionized water. The total dropwise addition time is 2.5 hours. During the dropwise addition process, ammonium persulfate initiator is added simultaneously at a rate of 0.2% of the total mass of the shell monomers. After the dropwise addition is complete, the system is heated to 80–85°C and the reaction is maintained at this temperature for 2 hours to complete the polymerization reaction. The total mass of the shell monomers in this step is 200g, including 70g of hexafluorobutyl methacrylate, 50g of vinyltriethoxysilane, 16g of the polymerizable hindered amine light stabilizer UV-292, 14g of methacryloyloxyethyl phosphate, and the remainder being butyl acrylate for adjusting the proportions. The fluorocarbon segments introduced by the shell monomer intertwine with the polysiloxane segments during polymerization, forming a co-continuous network structure that imparts ultra-low surface energy and UV aging resistance to the coating. The polymerizable flame-retardant monomer contains double-bond functional groups, which can be directly integrated into the polymer chain, preventing the migration and precipitation of flame retardants.

[0064] The fourth step involves post-treatment of the emulsion: the polymerization product is naturally cooled to below 40°C, ammonia is added to adjust the pH of the system to 7.5–8.5, and after thorough stirring, the mixture is filtered through a 200-mesh filter to obtain a fluorosilicone ultra-weather-resistant core-shell emulsion. In this embodiment, the emulsion prepared has a core-shell mass ratio of 50:50, a fluorine content of 11% in the shell layer, a silicon content of 5%, a solid content of 48%, and an average latex particle size of 180 nm. Under these parameters, the emulsion exhibits good storage stability, showing no stratification or sedimentation after 6 months of sealed storage at room temperature.

[0065] The preparation of interface-enhanced self-healing microcapsules is as follows: In this embodiment, interface-enhanced self-healing microcapsules are prepared by in-situ polymerization. Melamine-formaldehyde resin is used as a pH-responsive wall material, which is coated with an epoxy resin-based repair agent. Then, polymerizable double bonds are introduced on the surface of the wall material by grafting with a silane coupling agent to achieve covalent bonding between the microcapsules and the emulsion matrix.

[0066] First, an oil-phase core material was prepared. 100g of bisphenol A type epoxy resin E-51 was added, along with 15g of reactive diluent butyl glycidyl ether and 3.5g of catalyst 2-methylimidazole. The mixture was stirred evenly at room temperature. Then, 10g of hydroxyl-modified polydimethylsiloxane, which had undergone vacuum drying, was added. The mixture was heated to 50–60℃ and stirred for 1 hour to obtain a homogeneous oil-phase system. The core material, primarily composed of epoxy resin, was combined with a reactive diluent to reduce viscosity. With the addition of a latent catalyst, it can slowly cure at room temperature after release, filling microcracks in the coating. The modified silicone oil enhances the surface energy of the repaired coating, ensuring the restoration of waterproof performance.

[0067] Next, prepare the aqueous phase by weighing 300-500g of deionized water, adding 3.5g of a composite emulsifier (a mixture of sodium salt of styrene-maleic anhydride copolymer and sodium dodecyl sulfate in a 2:1 mass ratio), and then adding 2g of polyvinyl alcohol. Stir until completely dissolved. Adjust the pH of the system to 4.0-5.0 with formic acid to obtain a continuous aqueous phase. The combination of the composite emulsifier and thickener can improve the stability of the emulsion, prevent oil droplet aggregation, and ensure uniform microcapsule particle size.

[0068] To prepare a melamine-formaldehyde prepolymer, melamine and formaldehyde were weighed and mixed at a molar ratio of 1:3. The pH was adjusted to 8.0–9.0 with triethanolamine, and the mixture was heated to 70°C and stirred for 30 minutes to obtain a transparent melamine-formaldehyde prepolymer solution. This solution was then cooled for later use. The prepolymer prepared under alkaline conditions has a lower molecular weight, but it can be gradually polymerized and crosslinked under subsequent acidic conditions to form a dense wall material.

[0069] Subsequently, emulsification and coating are performed. The prepared oil phase is slowly added to the aqueous phase, and a high-speed shear emulsifier is turned on. Shear emulsification is carried out at a speed of 8000-12000 r / min for 10-20 min to form a stable oil-in-water emulsion. The emulsion is transferred to a reaction vessel, stirred, and heated to 60-70℃. A melamine-formaldehyde prepolymer solution is slowly added dropwise. During the addition process, formic acid is used to maintain the pH of the system at 3.5-4.5. After the addition is completed, the reaction is maintained at this temperature for 2-4 hours. The wall material polymerizes in situ on the surface of the oil droplets to form a microcapsule suspension. The melamine-formaldehyde resin wall material has pH-responsive characteristics and will swell and rupture in an acidic environment, triggering the release of the repair agent.

[0070] Next, grafting modification was performed. The microcapsule suspension was cooled to 40°C, and γ-methacryloxypropyltrimethoxysilane was added at an amount of 3–8% of the microcapsule solid content. The pH of the system was adjusted to 4.0–5.0 with acetic acid, and the temperature was raised to 40–50°C with stirring for 1–2 hours. This allowed the silane coupling agent to be grafted onto the surface of the microcapsule wall material via silanol condensation, introducing polymerizable double-bond functional groups. The grafted microcapsule surface has reactive sites that can covalently bond with the emulsion matrix during film formation, avoiding weak interfaces between the microcapsules and the matrix.

[0071] Finally, post-processing was performed. The grafted and modified microcapsule suspension was centrifuged to remove the supernatant. The microcapsules were then washed three times alternately with deionized water and anhydrous ethanol to remove unreacted monomers and emulsifiers remaining on the surface. The washed product was dried in a vacuum drying oven at 40–50°C for 12 hours to obtain the interface-reinforced self-healing microcapsules. The microcapsules prepared in this example had an average particle size of 10 μm, a repair agent encapsulation rate of 88%, and a pH response trigger threshold of pH 5.0. Under acidic conditions, the wall material swelled and ruptured, releasing the internal repair agent.

[0072] The pretreatment of graded natural colored sand is as follows: In this embodiment, multi-graded natural colored sand is used as aggregate. The surface treatment with silane coupling agent is used to improve the interfacial bonding force between the colored sand and the resin matrix, and to prevent moisture from penetrating along the interface.

[0073] Natural colored sand in the 20-120 mesh range is selected for gradation, with 20% being 40 mesh, 55% being 60-80 mesh, and 25% being 100-120 mesh. This multi-gradation of colored sand allows for close packing, reducing resin usage while ensuring a delicate coating texture and a realistic stone-like effect.

[0074] Mix colored sands of various grades evenly according to the specified ratio, and spray with a dilute solution of silane coupling agent. The silane coupling agent used is γ-aminopropyltriethoxysilane, and the dilute solution is diluted with anhydrous ethanol to a mass fraction of 5%. Continuous stirring is maintained during the spraying process, with a total stirring time of 15–20 minutes, to ensure that the coupling agent evenly coats the surface of the colored sand particles. After stirring, place the colored sand in an oven and dry it at 100–105℃ for 2–4 hours. The moisture content should not exceed 0.2%, resulting in pretreated colored sand, which should be sealed for later use. Drying prevents moisture from being introduced into the colored sand, affecting the storage stability of the coating. The silane coupling agent can form molecular bridges between the colored sand and the resin, improving the interfacial adhesion strength.

[0075] The preparation of high weather-resistant imitation stone paint is as follows: In this embodiment, a low-speed stepwise feeding process is used to prepare the finished imitation stone paint, avoiding high shear damage to the microcapsule structure, ensuring uniform dispersion of each reactive component, and forming a complete three-dimensional cross-linked network after film formation.

[0076] The first step involves preparing the basic mixing system. Deionized water, antifreeze, film-forming aid, and pH adjuster are added sequentially to a dispersion vessel. Stirring is started at 300 rpm for 5–10 minutes to obtain a homogeneous first mixture. In this step, 60 parts of deionized water are used, 10 parts of propylene glycol are used as the antifreeze, 14 parts of dodecyl alcohol ester are used as the film-forming aid, and 2 parts of 2-amino-2-methyl-1-propanol are used as the pH adjuster. The antifreeze lowers the minimum film-forming temperature of the coating, ensuring complete film formation under low-temperature application conditions. The film-forming aid temporarily softens the latex particles, promoting particle fusion during film formation.

[0077] The second step involves adding a multifunctional reactive additive composite package. To the first mixing system, polymerizable HALS hindered amine light stabilizer, methacryloyloxyethyl phosphate, polymerizable silane coupling agent, reactive fluorinated surfactant, nano-antimony-doped tin oxide dispersion, and nano-antimony-doped tin oxide / indium tin oxide composite infrared reflective slurry are added sequentially. The stirring speed is increased to 400–600 r / min, and stirring is continued for 10–15 min to obtain the second mixing system. The amounts of each component in this step are as follows: 2.5 parts polymerizable HALS hindered amine light stabilizer, 2.5 parts methacryloyloxyethyl phosphate, 2 parts polymerizable silane coupling agent, 1 part reactive fluorinated surfactant, 3 parts nano-antimony-doped tin oxide dispersion, and 2 parts nano-antimony-doped tin oxide / indium tin oxide composite infrared reflective slurry. The total amount of the composite package is 13 parts. All of the above components contain polymerizable functional groups, which can participate in the cross-linking reaction during the subsequent film formation process, avoiding the problem of easy migration and precipitation of ordinary additives. Nano-infrared reflective fillers can reflect the near-infrared band of the sun, reduce the temperature rise of the coating surface, achieve heat insulation effect, and at the same time reduce the infrared radiation characteristics of objects, thus possessing infrared stealth adaptability.

[0078] The third step involves dispersing the self-healing microcapsules. Interface-enhanced self-healing microcapsules are mixed with deionized water at a mass ratio of 1:2, and dispersed using ultrasound for 5–10 minutes to form a uniform microcapsule suspension. This microcapsule suspension is then slowly added to the second mixing system, with the stirring speed reduced to 300–500 rpm, and stirred for 10–15 minutes to obtain the third mixing system. The total amount of interface-enhanced self-healing microcapsules used in this step is 30 parts. Pre-dispersion prevents agglomeration of the microcapsules upon direct addition, and low-speed stirring avoids damage to the microcapsule wall structure from high shear forces, ensuring the microcapsules remain intact during coating storage and preventing premature leakage of the repair agent.

[0079] In the fourth step, a fluorosilicone core-shell emulsion is added. The fluorosilicone ultra-weather-resistant core-shell emulsion is added to the third mixing system, and the stirring speed is adjusted to 200–400 r / min. The mixture is stirred for 10–20 min to obtain the fourth mixing system. In this step, 240 parts of the fluorosilicone ultra-weather-resistant core-shell emulsion are used. During stirring, the emulsion, microcapsules, and additives are thoroughly mixed, and the reactive groups on the surface of each component are uniformly dispersed, providing a basis for the cross-linking reaction in the film-forming stage.

[0080] The fifth step involves adding pretreated colored sand. Add the pretreated colored sand to the fourth mixing system in batches, with each batch not exceeding one-third of the total mass. Stir for 1-2 minutes after each batch is added, and continue stirring for 2 minutes after all batches are added to obtain the fifth mixing system. The total amount of graded natural colored sand used in this step is 680 parts. Adding it in batches avoids sand settling and agglomeration, ensuring a uniform and stable coating system, and also reduces air bubbles generated during stirring.

[0081] Step 6: Thickening, Filtration, and Packaging. Slowly add the thickener (polyurethane type) to the fifth mixing system while stirring, checking the paint viscosity until it reaches 90-110 KU. After adjustment, filter through a 40-mesh stainless steel sieve to remove any small agglomerated particles. Seal the filtrate and package it to obtain the high weather-resistant stone-like paint product. The total amount of thickener used in this step is 4 parts. Polyurethane type thickener provides good thixotropic properties, preventing sagging during application and sedimentation during storage.

[0082] In this embodiment, during the film-forming process of the stone-like paint, as moisture evaporates, the latex particles gradually fuse. The reactive groups of the fluorosilicone ultra-weather-resistant core-shell emulsion shell, the double-bonded functional groups on the surface of the interface-strengthened self-healing microcapsules, and the polymerizable functional groups of the multifunctional reactive additive composite package undergo free radical copolymerization at the film-forming temperature, forming a three-dimensional network structure connected by covalent bonds. This structure increases the overall crosslinking density of the coating, enhances the interfacial bonding between components, avoids weak interfaces between the microcapsules and the emulsion matrix, and reduces the migration of small molecule additives, thus maintaining the coating's various properties for a long time. When the coating develops microcracks due to thermal expansion and contraction or external forces, acidic rainwater or corrosive media penetrate the cracks, triggering the swelling and rupture of the microcapsule wall material, releasing the repair agent. The repair agent fills the cracks and gradually solidifies, resealing the damaged area and restoring the coating's waterproof performance.

[0083] In this embodiment, a set of comparative embodiments is set up to verify the technical effect of the core structure of this solution. The total amount of basic aggregates and additives and the preparation process of the comparative embodiments are consistent with those of the above embodiments, with only the core functional components being adjusted. The adjustments include three points: First, the film-forming emulsion uses a common fluorosilicone blend emulsion, that is, a physical mixture of commercially available water-based fluorocarbon emulsion and silicone-acrylic emulsion at a mass ratio of 1:1, without adopting a core-shell polymerization structure, and the emulsion has no directional fluorosilicone enrichment layer. Second, the self-healing microcapsules are not modified by silane coupling agent grafting, and there are no polymerizable double bond functional groups on the surface; the microcapsules and the emulsion matrix are only physically intercalated. Third, the additives use common physical blending additives, which do not contain polymerizable functional groups and cannot participate in the crosslinking reaction.

[0084] The stone-like paints prepared in the examples and comparative examples were made into standard test samples using the same process. After curing in a standard environment of 23°C and 50% relative humidity for 7 days, performance tests were conducted. The test items covered the dimensions of weather resistance, waterproofing, self-healing, fireproofing, heat insulation, and mechanical properties. The test results are shown in the table below.

[0085] Artificially accelerated weathering loss rate GB / T1865-2009, 1000h 8% 25% Water resistance GB / T1733-1993, 96h No bubbling, no peeling Bubbling at the edges, localized sand shedding Scratch self-healing efficiency Water contact angle recovery rate 92% 35% Oxygen Index GB / T2406.2-2009 28% 22% Near-infrared reflectance 800–2500 nm band 78% 52% Coating tensile strength GB / T5210-2006 2.1MPa 1.4MPa Washability GB / T9266-2009, 2000 times No sand shedding, no exposed base material Localized sand shedding and exposed base

[0086] The test results show that the stone-like paint prepared in this embodiment outperforms the comparative embodiment in several core performance aspects. The core-shell structured fluorosilicone emulsion enriches fluorosilicone segments on the coating surface, exhibiting a lower surface energy advantage compared to physically blended emulsions, resulting in significantly improved weather resistance and water resistance. Interface-grafted microcapsules and reactive additives are covalently integrated into the matrix network, enhancing the overall mechanical properties of the coating while ensuring the microcapsule's response triggering efficiency, leading to a significantly better self-healing effect than physically blended systems. Infrared reflective fillers are stably dispersed in the cross-linked network through reactive additives, effectively reflecting solar infrared wavelengths, reducing the coating surface temperature, achieving thermal insulation, and simultaneously reducing the infrared signature of objects. Phosphorus-containing flame-retardant components are integrated into the cross-linked network, forming a dense char layer during combustion to block heat and oxygen, thus improving the coating's fire resistance rating.

[0087] The above embodiments fully present the specific implementation process of this technical solution. Through the synergistic effect of emulsion structure design, microcapsule interface modification and reactive additive compounding, while retaining the stone-like decorative effect of real stone paint, the weather resistance, durability and multiple protective properties of the coating are simultaneously improved, making it suitable for use on exterior walls in areas with high temperature and humidity, strong ultraviolet radiation and large temperature differences.

[0088] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A high weather-resistant imitation stone paint, characterized in that, It consists of the following components in parts by weight: Fluorosilicone ultra-weather-resistant core-shell emulsion, 180–300 parts; Interface-enhanced self-healing microcapsules, 15-50 parts; Multifunctional reactive adjuvant compound package, 5-20 parts; Graded natural colored sand, 600-750 parts; Deionized water, 40-80 parts; pH adjuster, 1-3 parts; Antifreeze, 5-15 parts; Film-forming aid, 8-20 parts; Thickener, 2-6 parts; The fluorosilicone ultra-weather-resistant core-shell emulsion has a core layer and a shell layer. The shell layer contains a co-continuous network structure formed by fluorocarbon segments and polysiloxane segments, and the shell layer also contains reactive groups. The interface-enhanced self-healing microcapsules have a pH-responsive wall material, and the surface of the wall material is modified by grafting a polymerizable silane coupling agent to introduce double bond functional groups. The multifunctional reactive additive composite contains at least one polymerizable functional group; The double-bonded functional groups of the interface-enhanced self-healing microcapsules, the reactive groups of the fluorosilicone ultra-weather-resistant core-shell emulsion, and the polymerizable functional groups of the multifunctional reactive additive composite package form a three-dimensional network structure with covalent bonds through free radical copolymerization during the film formation process.

2. The high weather-resistant imitation stone paint according to claim 1, characterized in that, The fluorosilicone ultra-weather-resistant core-shell emulsion is prepared by a two-step seed pre-emulsification core-shell polymerization process of core layer monomers and shell layer monomers. The core layer monomers contain 40-65 parts by weight of methyl methacrylate, 20-40 parts by weight of butyl acrylate, 2-6 parts by weight of methacrylic acid and 1-6 parts by weight of crosslinking monomers. The shell layer monomers contain 15-30 parts by weight of fluorinated monomers, 10-25 parts by weight of silicon-containing monomers, 2-5 parts by weight of polymerizable hindered amine light stabilizer and 2-5 parts by weight of reactive phosphorus-containing flame retardant monomers.

3. The high weather-resistant imitation stone paint according to claim 1, characterized in that, The interface-enhanced self-healing microcapsules are formed by in-situ polymerization, with melamine-formaldehyde resin, polyurea, or polyurethane as the wall material raw material, and the polymerizable silane coupling agent being γ-methacryloyloxypropyltrimethoxysilane.

4. The high weather-resistant imitation stone paint according to claim 1, characterized in that, The multifunctional reactive additive composite package comprises: 1-4 parts by weight of polymerizable HALS hindered amine light stabilizer, 1-4 parts by weight of methacryloyloxyethyl phosphate, 1-3 parts by weight of polymerizable silane coupling agent, 0.5-2 parts by weight of reactive fluorinated surfactant, 1-5 parts by weight of nano-antimony-doped tin oxide dispersion, and 0.5-4 parts by weight of nano-antimony-doped tin oxide and indium tin oxide composite infrared reflective paste.

5. The high weather-resistant imitation stone paint according to claim 1, characterized in that, The graded natural colored sand is 20-120 mesh natural colored sand. By mass ratio, 40 mesh natural colored sand accounts for 15-25%, 60-80 mesh natural colored sand accounts for 50-60%, and 100-120 mesh natural colored sand accounts for 20-30%. The graded natural colored sand is pre-treated with a dilute solution of silane coupling agent.

6. The high weather-resistant imitation stone paint according to claim 1, characterized in that, The antifreeze is propylene glycol or ethylene glycol, the film-forming aid is dodecyl alcohol ester or dipropylene glycol butyl ether, and the thickener is an alkali-swelling thickener or a polyurethane thickener.

7. A method for preparing a high weather-resistant imitation stone paint, applicable to the high weather-resistant imitation stone paint according to any one of claims 1 to 6, characterized in that, Includes the following steps: Step 1: Mix graded natural colored sand according to the gradation ratio, spray with a dilute solution of silane coupling agent and stir for 15-20 minutes, then dry at 100-105℃ for 2-4 hours until the moisture content is ≤0.2% to obtain pretreated colored sand; Step 2: Add deionized water, antifreeze, film-forming aid and pH adjuster to the dispersion vessel in sequence, stir for 5-10 minutes to obtain the first mixed system; Step 3: Add each component of the multifunctional reactive additive composite package to the first mixing system in sequence, and stir at 400-600 rpm for 10-15 min to obtain the second mixing system; Step 4: Disperse the interface-enhanced self-healing microcapsules in deionized water at a mass ratio of microcapsules to water of 1:2, and disperse with ultrasonic assistance for 5-10 minutes to form a microcapsule suspension. Add the microcapsule suspension to the second mixing system and stir at 300-500 r / min for 10-15 minutes to obtain the third mixing system. Step 5: Add fluorosilicone ultra-weather-resistant core-shell emulsion to the third mixing system and stir at 200-400 r / min for 10-20 min to obtain the fourth mixing system; Step 6: Add the pretreated colored sand prepared in Step 1 to the fourth mixing system in batches, stirring for 1-2 minutes after each addition to obtain the fifth mixing system; Step 7: Add thickener to the fifth mixing system, adjust the coating viscosity to 90-110 KU, filter with a 40-mesh stainless steel sieve, and package to obtain high weather-resistant imitation stone paint.

8. The method for preparing a high weather-resistant imitation stone paint according to claim 7, characterized in that, The fluorosilicone ultra-weather-resistant core-shell emulsion is prepared using the following steps: Step 1: Mix 5-10% of the total amount of core layer monomers, composite emulsifier and part of deionized water for pre-emulsification, add initiator, heat to 78-82℃ and react for 30-45 minutes to generate seed emulsion; Step 2: The remaining core layer monomer pre-emulsion is added dropwise to the seed emulsion at a uniform rate over 2-3 hours, while maintaining the temperature at 78-82°C. After the addition is completed, the temperature is maintained for 1 hour to obtain the core layer emulsion. Step 3: Cool down to 70-75℃, and add the shell monomer pre-emulsion to the core emulsion at a uniform rate over 2-3 hours, while simultaneously adding the initiator. After the addition is complete, raise the temperature to 80-85℃ and keep it at that temperature for 2 hours to obtain the polymerization product. Step four: Cool the polymer product to below 40°C, adjust the pH to 7.5-8.5 with ammonia or organic amine, filter and discharge to obtain a fluorosilicone ultra-weather-resistant core-shell emulsion.

9. The method for preparing a high weather-resistant imitation stone paint according to claim 7, characterized in that, The interface-enhanced self-healing microcapsules were prepared using the following steps: Step 1: Take 100 parts by weight of bisphenol A type epoxy resin, 10-20 parts by weight of reactive diluent, and 2-5 parts by weight of catalyst and stir evenly. Add 5-15 parts by weight of modified silicone oil that has been vacuum dried and stir at 50-60℃ for 1 hour to form an oil phase. Step 2: Take 300-500 parts by weight of deionized water, add 2-5 parts by weight of a composite emulsifier consisting of sodium salt of styrene-maleic anhydride and sodium dodecyl sulfate in a mass ratio of 2:1, and 1-3 parts by weight of polyvinyl alcohol, stir to dissolve, and adjust the pH to 4.0-5.0 to form an aqueous phase; Step 3: Prepare a solution of melamine and formaldehyde by mixing melamine and formaldehyde at a molar ratio of 1:3 and reacting at pH 8.0–9.0 and 70°C for 30 minutes to obtain a melamine-formaldehyde prepolymer solution. Step 4: Add the oil phase to the aqueous phase and perform high-speed shear emulsification at a speed of 8000-12000 r / min for 10-20 min to form a stable oil-in-water emulsion. Step 5: Add the melamine-formaldehyde prepolymer solution dropwise to the oil-in-water stabilized emulsion, adjust the pH to 3.5-4.5 with formic acid, and react at 60-70°C for 2-4 hours. The wall material is polymerized in situ and coated onto the surface of the oil phase to obtain a microcapsule suspension. Step 6: Cool the microcapsule suspension to 40°C, add γ-methacryloxypropyltrimethoxysilane, the amount of γ-methacryloxypropyltrimethoxysilane being 3-8% of the solid content of the microcapsules, adjust the pH to 4.0-5.0 with acetic acid, and stir at 40-50°C for 1-2 hours to graft γ-methacryloxypropyltrimethoxysilane onto the surface of the microcapsule wall material to obtain grafted modified microcapsules; Step 7: Centrifuge or filter the grafted modified microcapsules, wash them three times alternately with deionized water and anhydrous ethanol, and vacuum dry them at 40-50°C for 12 hours to obtain interface-enhanced self-healing microcapsules.

10. The method for preparing a high weather-resistant imitation stone paint according to claim 8, characterized in that, The mass ratio of the core layer to the shell layer in the fluorosilicone ultra-weather-resistant core-shell emulsion is 40:60 to 55:

45. The shell layer contains 8wt% to 15wt% fluorine and 3wt% to 8wt% silicon. The solid content of the fluorosilicone ultra-weather-resistant core-shell emulsion is 45% to 50%, and the latex particle size is 120 to 250 nm.

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