A stone-like paint emulsion convenient for spraying and a preparation method thereof

Abstract

The application discloses a real stone paint emulsion convenient to spray and a preparation method thereof. The emulsion comprises a water phase and core-shell structure latex particles dispersed in the water phase. The core-shell structure latex particle comprises a flexible film-forming core layer and a shear response shell layer covering the outside of the core layer. The shear response shell layer is formed by polymerization of shell monomers containing methyl methacrylate, butyl acrylate, a carboxyl-containing unsaturated monomer, a phosphate group-containing acrylate monomer, a long-chain alkyl polyether acrylate monomer and a silane coupling type vinyl monomer. The carboxyl units are at least partially neutralized to form carboxylate structural units. The emulsion can improve the low shear support and high shear flow of the real stone paint system, improve the spraying smoothness, reduce the phenomena of color sand settlement, gun blockage, material breakage, sagging and coating blooming.

Description

Technical Field

[0001] This invention belongs to the field of real stone paint spraying technology, specifically relating to a real stone paint emulsion that is easy to spray and its preparation method. Background Technology

[0002] Stone-like paint is a type of architectural exterior wall coating that uses synthetic resin emulsion as the main film-forming substance and natural or artificial colored sand as the main aggregate. Due to its appearance closely resembling natural stone and its advantages such as strong decorative properties, high construction efficiency, and relatively low cost, it has been widely used in building exteriors, commercial building facades, and old wall renovation. Stone-like paint is typically applied by spraying. During application, the coating system needs to have good suspension stability in its storage state, good flowability and atomization in pumping and spraying, and the ability to quickly recover a certain degree of structural strength after being sprayed onto the wall surface to avoid problems such as sagging, sand accumulation, uneven coloring, and uneven sand particle distribution.

[0003] In existing stone-like paint systems, the emulsion typically plays a primary role in adhesion, film formation, and weather protection, while spray application performance largely depends on the addition of thickeners, cellulose ethers, bentonite, silicate thixotropic agents, polyurethane associative thickeners, or other rheology modifiers. While these methods can improve the system's viscosity and anti-settling properties to some extent, the high content of colored sand, wide particle size distribution, and high solids content in stone-like paint mean that relying solely on additives to adjust rheological properties can easily lead to problems such as insufficient viscosity at low shear levels causing colored sand sedimentation, or excessively high viscosity at high shear levels leading to increased spraying resistance, nozzle clogging, and discontinuous material output.

[0004] Furthermore, the compatibility of added thickeners and thixotropic agents with emulsions, colored sand, and other additives is greatly affected by the formulation system. During long-term storage, temperature changes, or dilution during application, phenomena such as viscosity drift, localized flocculation, colored sand stratification, or spray mottling may occur. Especially in mechanical spraying, stone paint needs to undergo multiple states, including storage, stirring, pumping, spray gun shearing, and wall spreading. The system must have sufficient structural support when stationary, low flow resistance during high-shear spraying, and rapid recovery of anti-sagging ability after spraying. Existing methods of adjusting solely by adding rheology modifiers are insufficient to meet these multiple application requirements.

[0005] Meanwhile, although ordinary acrylic emulsions or silicone-acrylic emulsions have good film-forming properties and weather resistance, their latex particle surfaces have limited interfacial affinity for inorganic particles such as natural colored sand and quartz sand. When the emulsion is compounded with a large amount of inorganic colored sand, the latex particles are unable to form a stable and uniform interfacial adsorption layer on the sand particle surface. This can easily lead to the colored sand agglomerating, settling, or unevenly distributing during storage and spraying, thereby affecting the continuity of the stone paint spraying, the uniformity of the coating, and the final decorative effect. Summary of the Invention

[0006] To address the aforementioned issues, this invention provides a stone-like paint emulsion that is easy to spray and its preparation method. The emulsion itself can participate in the rheological regulation of the stone-like paint system and improve the stability of the inorganic particle interface, thereby reducing dependence on external thixotropic additives while improving the spraying smoothness, storage stability, and coating appearance quality of the stone-like paint.

[0007] The technical solution provided by this invention is as follows: On the one hand, a real stone paint emulsion that is easy to spray and its preparation method include an aqueous phase and core-shell structured latex particles dispersed in the aqueous phase. The core-shell structured latex particles include a flexible film-forming core layer and a shear-responsive shell layer covering the outside of the flexible film-forming core layer. Based on a total monomer mass of 100 parts, 40 to 70 parts of the core layer monomers form the flexible film-forming core layer, and 30 to 60 parts of the shell monomers form the shear-responsive shell layer. Shell monomers include methyl methacrylate, butyl acrylate, carboxyl-containing unsaturated monomers, phosphate-containing acrylate monomers, long-chain alkyl polyether acrylate monomers, and silane-coupled vinyl monomers; Among them, the carboxyl units formed by the carboxyl-containing unsaturated monomers are at least partially neutralized to form carboxylate structural units, and the shear-response shell contains carboxylate structural units, phosphate structural units, long-chain alkyl polyether side chain structural units, and silane structural units.

[0008] In some embodiments, the core layer monomers, based on a total mass of 100 parts, include 40-65 parts of butyl acrylate, 5-25 parts of isooctyl acrylate, 20-45 parts of methyl methacrylate, and 0-15 parts of styrene.

[0009] In some embodiments, based on a total mass of 100 parts of shell monomers, the shell monomers include 35-65 parts of methyl methacrylate, 15-35 parts of butyl acrylate, 3-10 parts of methacrylic acid, 1-5 parts of acrylic acid, 1-6 parts of phosphate ester-containing acrylate monomers, 1-8 parts of long-chain alkyl polyether acrylate monomers, and 0.5-3 parts of silane-coupled vinyl monomers.

[0010] In some embodiments, the long-chain alkyl polyether acrylate monomer is at least one selected from dodecyl polyoxyethylene methacrylate, hexadecyl polyoxyethylene methacrylate, octadecyl polyoxyethylene methacrylate, dodecyl polyoxyethylene acrylate, hexadecyl polyoxyethylene acrylate, and octadecyl polyoxyethylene acrylate.

[0011] In some embodiments, the phosphate-containing acrylate monomer is at least one of hydroxyethyl methacrylate phosphate, hydroxyethyl acrylate phosphate, polyoxyethylene ether phosphate acrylate, and polyoxyethylene ether phosphate methacrylate. The silane-coupled vinyl monomer is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, methacryloyloxypropyltrimethoxysilane, and methacryloyloxypropyltriethoxysilane.

[0012] In some embodiments, the stone paint emulsion further includes an emulsifier, which includes anionic emulsifiers and nonionic emulsifiers; The anionic emulsifier is at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium allyloxyhydroxypropyl sulfonate, and fatty alcohol polyoxyethylene ether sulfate; The nonionic emulsifier is at least one of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, and isomeric alcohol polyoxyethylene ether.

[0013] In some embodiments, the solid content of the stone paint emulsion is 45-52%, the pH value is 7.5-8.8, the average particle size of the core-shell structured latex particles is 100-220 nm, and the mass ratio of the flexible film-forming core layer to the shear-responsive shell layer is 1:0.4-1:1.2.

[0014] On the other hand, a method for preparing a sprayable stone paint emulsion includes the following steps: S1. Mix and pre-emulsify the core layer monomer, emulsifier and water to obtain the core layer pre-emulsion; S2. Mix and pre-emulsify the shell monomer, emulsifier and water to obtain a shell pre-emulsion. The shell monomers include methyl methacrylate, butyl acrylate, carboxyl-containing unsaturated monomers, phosphate ester-containing acrylate monomers, long-chain alkyl polyether acrylate monomers and silane-coupled vinyl monomers. S3. Add water, emulsifier and buffer to the reactor, heat up and add initiator and part of core layer pre-emulsion to carry out seed polymerization to obtain seed latex particles. S4. Continue to add the remaining core layer pre-emulsion to the system containing seed latex particles to form a flexible film-forming core layer on the outside of the seed latex particles. S5. After the flexible film-forming core layer is formed, continue to add shell pre-emulsion to the reaction system so that the shell monomers continue to polymerize on the outside of the flexible film-forming core layer to form a shear-responsive shell layer. S6. After the heat preservation reaction, the temperature is lowered, and an alkaline neutralizing agent is added to adjust the pH value so that the carboxyl units in the shear response shell are at least partially neutralized to form carboxylate structural units, thus obtaining a real stone paint emulsion that is easy to spray.

[0015] In some embodiments, the temperature for seed polymerization in step S3 is 75–85°C; In step S4, the core layer pre-emulsion is added over a period of 1.5 to 3.5 hours. In step S5, the dropwise addition time of the shell pre-emulsion is 1 to 3 hours; In step S6, the alkaline neutralizing agent is at least one of ammonia, triethylamine, dimethylethanolamine, and 2-amino-2-methyl-1-propanol.

[0016] In some embodiments, in step S5, the shell preemulsion is added after the core preemulsion has been added and kept warm for 10 to 40 minutes; After the pre-emulsion in the shell layer is added, continue the reaction at 75-85℃ for 0.5-2 hours, then cool down to 40-50℃ and add the alkaline neutralizer.

[0017] In summary, the beneficial effects of this invention are: (1) The easy-to-spray stone paint emulsion provided by this invention adopts core-shell structured latex particles. The latex particles include a flexible film-forming core layer and a shear-responsive shell layer. The shear-responsive shell layer contains carboxylate structural units, long-chain alkyl polyether side-chain structural units, phosphate ester structural units, and silane structural units, enabling the emulsion itself to participate in the rheological regulation of the stone paint system. Compared with the method of simply relying on the addition of thickeners or thixotropic agents to improve the construction performance, this invention can form a low-shear support and high-shear flow regulation basis at the latex particle structure level, thereby improving the adaptability of the stone paint emulsion under different construction conditions.

[0018] (2) The present invention enables the stone paint system to have good structural strength under static or low shear conditions by the synergistic effect of long-chain alkyl polyether side chain structural units and at least partially neutralized carboxylate structural units, which can reduce the sedimentation, delamination and sagging of colored sand after spraying; under the high shear conditions formed by spraying, the reversible hydrophobic association structure can partially dissociate, thereby reducing the apparent viscosity of the system, thereby reducing pumping and spraying resistance, reducing gun blockage, material interruption and pulse discharge; after spraying, the shear effect is weakened, the system structure can recover faster, and the coating sand particles are spread more evenly.

[0019] (3) The present invention introduces phosphate ester structural units and silane structural units in the shear response shell. The phosphate ester structural units can enhance the interfacial affinity between latex particles and inorganic particles such as natural colored sand, quartz sand, and calcined sand, and reduce the agglomeration and uneven distribution of colored sand. The silane structural units can improve the interfacial bonding force and coating density after the emulsion forms a film, thereby improving the adhesion, water resistance, alkali resistance and weather resistance of the real stone paint coating. This invention can improve the spraying performance while taking into account the long-term performance of the coating. Detailed Implementation

[0020] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. The following embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0021] This invention provides a sprayable stone-like paint emulsion, comprising an aqueous phase and core-shell structured latex particles dispersed in the aqueous phase. The core-shell structured latex particles include a flexible film-forming core layer and a shear-responsive shell layer covering the outer side of the flexible film-forming core layer. The flexible film-forming core layer primarily imparts good low-temperature film-forming properties, adhesion, and coating flexibility to the emulsion; the shear-responsive shell layer primarily improves the compatibility between the emulsion and inorganic particles such as natural colored sand, quartz sand, and calcined sand, and enables the emulsion to form a rheological structure suitable for spray application within the stone-like paint system.

[0022] Based on a total monomer mass of 100 parts, the core layer monomer forming the flexible film-forming core layer comprises 40–70 parts, and the shell layer monomer forming the shear-responsive shell layer comprises 30–60 parts. The core layer monomer may include at least two of butyl acrylate, isooctyl acrylate, methyl methacrylate, and styrene. By combining soft monomers such as butyl acrylate and isooctyl acrylate with hard monomers such as methyl methacrylate and styrene, the flexible film-forming core layer can possess both film-forming flexibility and a certain degree of cohesive strength.

[0023] The shell monomers include methyl methacrylate, butyl acrylate, carboxyl-containing unsaturated monomers, phosphate-containing acrylate monomers, long-chain alkyl polyether acrylate monomers, and silane-coupled vinyl monomers. The carboxyl-containing unsaturated monomers can be one or more of methacrylic acid, acrylic acid, and itaconic acid, preferably a blend of methacrylic acid and acrylic acid. After neutralization with an alkaline neutralizing agent, the carboxyl units formed by the carboxyl-containing unsaturated monomers can form carboxylate structural units, giving the outer layer of the latex particles a certain degree of hydration and stretching ability, which helps improve the dispersion stability of the emulsion in the stone-like paint system.

[0024] The phosphate ester-containing acrylate monomer can be at least one of hydroxyethyl methacrylate phosphate, hydroxyethyl acrylate phosphate, polyoxyethylene ether phosphate acrylate, and polyoxyethylene ether phosphate methacrylate. The phosphate ester structural unit can improve the affinity of the outer layer of latex particles for the surface of inorganic particles, enabling a more stable interfacial bond between the emulsion and aggregates such as natural colored sand and quartz sand in the stone-like paint, thereby reducing problems such as colored sand agglomeration, delamination, material breakage, and localized mottling during spraying.

[0025] The long-chain alkyl polyether acrylate monomer can be at least one of dodecyl polyoxyethylene methacrylate, hexadecyl polyoxyethylene methacrylate, octadecyl polyoxyethylene methacrylate, dodecyl polyoxyethylene acrylate, hexadecyl polyoxyethylene acrylate, and octadecyl polyoxyethylene acrylate. When the long-chain alkyl polyether side chain structural unit is located in the latex particle shell layer, it can form a reversible hydrophobic association structure between the latex particles. Under static or low-shear conditions, the hydrophobic association structure can improve the structural strength of the stone paint system and reduce colored sand settling and construction sagging. Under the high-shear conditions formed by spraying, the hydrophobic association structure partially dissociates, reducing the apparent viscosity of the system and facilitating the smooth passage of the stone paint through the spray gun and nozzle. After spraying, the shear effect weakens, the hydrophobic association structure recovers, and the paint has good anti-sagging properties and uniform sand particle distribution on the wall surface.

[0026] The silane-coupled vinyl monomer can be at least one of vinyltrimethoxysilane, vinyltriethoxysilane, methacryloxypropyltrimethoxysilane, and methacryloxypropyltriethoxysilane. The silane structural unit can improve the cross-linking density of latex particles after film formation and their adhesion to inorganic substrates and sand surfaces, thereby improving the water resistance, weather resistance, and adhesion of the stone-like paint coating.

[0027] The real stone paint emulsion of the present invention may further include an emulsifier, a buffer, an initiator, and an alkaline neutralizer. The emulsifier may include anionic and nonionic emulsifiers. The anionic emulsifier may be at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium allyloxyhydroxypropyl sulfonate, and fatty alcohol polyoxyethylene ether sulfate; the nonionic emulsifier may be at least one of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, and isomeric alcohol polyoxyethylene ether. The initiator may be at least one of ammonium persulfate, potassium persulfate, and sodium persulfate, or a redox initiation system may be used. The buffer may be at least one of sodium bicarbonate, disodium hydrogen phosphate, and sodium acetate. The alkaline neutralizer may be at least one of ammonia, triethylamine, dimethylethanolamine, and 2-amino-2-methyl-1-propanol.

[0028] The real stone paint emulsion of the present invention can be prepared by a semi-continuous seed emulsion polymerization method. Specifically, the core layer monomer, emulsifier, and water are first mixed and pre-emulsified to obtain a core layer pre-emulsion; then the shell layer monomer, emulsifier, and water are mixed and pre-emulsified to obtain a shell layer pre-emulsion. Subsequently, water, emulsifier, and buffer are added to a reaction vessel, and the temperature is raised to 75-85°C. Then, an initiator and part of the core layer pre-emulsion are added to carry out seed polymerization to obtain seed latex particles. After the seed latex particles are formed, the remaining core layer pre-emulsion is added dropwise to form a flexible film-forming core layer on the outside of the seed latex particles. After the core layer pre-emulsion is added and kept at a constant temperature for 10-40 minutes, the shell layer pre-emulsion is added dropwise to allow the shell layer monomers to continue to polymerize on the outside of the flexible film-forming core layer to form a shear-responsive shell layer. After the pre-emulsion in the shell is added, continue the reaction at a constant temperature for 0.5 to 2 hours, then cool down to 40 to 50°C, add an alkaline neutralizing agent to adjust the pH to 7.5 to 8.8, so that the carboxyl units in the shear response shell are at least partially neutralized to form carboxylate structural units. After filtration, a real stone paint emulsion that is easy to spray is obtained.

[0029] In a preferred embodiment, the obtained stone-like paint emulsion has a solid content of 45-52%, a pH value of 7.5-8.8, an average particle size of 100-220 nm for the core-shell structured latex particles, and a mass ratio of flexible film-forming core layer to shear-responsive shell layer of 1:0.4-1:1.2. When this emulsion is used in stone-like paint, it can reduce the amount of added thickeners and thixotropic agents, allowing the stone-like paint to maintain a more stable application state during storage, pumping, and spraying.

[0030] Example 1 This embodiment provides a stone-like paint emulsion that is easy to spray. The total mass of monomers involved in polymerization is 100 kg, of which 60 kg is core monomer and 40 kg is shell monomer.

[0031] The core layer monomers include 33 kg of butyl acrylate, 9 kg of isooctyl acrylate, and 18 kg of methyl methacrylate.

[0032] The shell monomers include 20 kg of methyl methacrylate, 10.8 kg of butyl acrylate, 2.8 kg of methacrylic acid, 1.2 kg of acrylic acid, 1.2 kg of hydroxyethyl methacrylate phosphate, 2.8 kg of octadecyl polyoxyethylene methacrylate, and 1.2 kg of methacryloxypropyltrimethoxysilane.

[0033] During preparation, the core layer monomer, a portion of the emulsifier, and deionized water were added to a pre-emulsification tank and stirred at high speed for 30 minutes to obtain a core layer pre-emulsion. The emulsifier used was a compound emulsifier of fatty alcohol polyoxyethylene ether sulfate and fatty alcohol polyoxyethylene ether, with a mass ratio of 2:1.

[0034] Shell monomers, a portion of emulsifier, and deionized water were added to another pre-emulsification tank and stirred at high speed for 30 minutes to obtain a shell pre-emulsion. Deionized water, sodium bicarbonate, and a portion of emulsifier were added to a reaction vessel, and after nitrogen purging to remove oxygen, the temperature was raised to 80°C. An ammonium persulfate aqueous solution and 10% of the core pre-emulsion were added, and the reaction was carried out for 20 minutes to form seed latex particles.

[0035] The remaining core layer pre-emulsion was then added dropwise at 80℃ over 2.5 hours; after addition, the temperature was maintained for 20 minutes. The shell layer pre-emulsion was then added dropwise over 2 hours. After the shell layer pre-emulsion was added, the temperature was maintained at 80℃ for another 1 hour to ensure complete monomer conversion. The temperature was then lowered to 45℃, and 2-amino-2-methyl-1-propanol was added to adjust the pH to 8.2. After filtration, a suitable stone paint emulsion for spraying was obtained.

[0036] The resulting emulsion had a solid content of approximately 48%, an average particle size of approximately 160 nm, and a pH of approximately 8.2. The emulsion appeared as a uniform milky-white liquid and showed no obvious stratification or gelation after standing.

[0037] Example 2 The difference between this embodiment and Embodiment 1 is that the core monomer is 55 kg and the shell monomer is 45 kg.

[0038] Based on a total mass of 100 parts of core layer monomers, the core layer monomers include 50 parts of butyl acrylate, 10 parts of isooctyl acrylate, 30 parts of methyl methacrylate, and 10 parts of styrene.

[0039] Based on a total mass of 100 parts of shell monomers, the shell monomers include 55 parts of methyl methacrylate, 25 parts of butyl acrylate, 6 parts of methacrylic acid, 2 parts of acrylic acid, 3 parts of hydroxyethyl acrylate phosphate, 6 parts of hexadecyl polyoxyethylene methacrylate, and 3 parts of vinyltrimethoxysilane.

[0040] The preparation method is basically the same as in Example 1, except that: the seed polymerization temperature is 78℃, the core layer pre-emulsion is added for 3 hours, the shell layer pre-emulsion is added for 2.5 hours, and the pH value is adjusted to 8.0 with ammonia after the shell layer polymerization is completed.

[0041] The resulting emulsion has a solid content of approximately 47% and an average particle size of approximately 180 nm. When used in stone-like paint systems, this emulsion exhibits good pump flowability and spray atomization.

[0042] Example 3 The difference between this embodiment and Embodiment 1 is that the core monomer is 65 kg and the shell monomer is 35 kg.

[0043] Based on a total mass of 100 parts of core layer monomers, the core layer monomers include 60 parts of butyl acrylate, 15 parts of isooctyl acrylate, and 25 parts of methyl methacrylate.

[0044] Based on a total mass of 100 parts of shell monomers, the shell monomers include 45 parts of methyl methacrylate, 30 parts of butyl acrylate, 8 parts of methacrylic acid, 4 parts of acrylic acid, 5 parts of polyoxyethylene ether phosphate methacrylate, 6 parts of dodecyl polyoxyethylene methacrylate, and 2 parts of methacryloyloxypropyltriethoxysilane.

[0045] The preparation method is basically the same as in Example 1, except that: the seed polymerization temperature is 82℃, the core layer pre-emulsion is added for 2 hours, the shell layer pre-emulsion is added for 1.5 hours, and the pH value is adjusted to 8.5 with dimethylethanolamine after the heat preservation reaction is completed.

[0046] The resulting emulsion has a solid content of approximately 49% and an average particle size of approximately 145 nm. This emulsion exhibits good film-forming flexibility and is suitable for exterior wall stone-like paint systems that require high low-temperature film-forming properties and crack resistance.

[0047] Comparative Example 1 This comparative example provides a common acrylate emulsion. Instead of using a core-shell stepwise polymerization method, this emulsion involves the semi-continuous polymerization of conventional acrylate monomers such as butyl acrylate, methyl methacrylate, and methacrylic acid after a one-time pre-emulsification. This emulsion does not contain phosphate-containing acrylate monomers, long-chain alkyl polyether acrylate monomers, or silane-coupled vinyl monomers. The resulting emulsion has a solid content of approximately 48% and a pH of approximately 8.0.

[0048] Comparative Example 2 This comparative example is basically the same as Example 1, except that long-chain alkyl polyether acrylate monomers are not added to the shell monomers, and the remaining monomers are supplemented with methyl methacrylate. Although this emulsion still has a core-shell structure and a certain affinity for inorganic particles, there is a lack of obvious reversible hydrophobic association structure between the latex particles.

[0049] Comparative Example 3 This comparative example is basically the same as Example 1, except that: no phosphate-containing acrylate monomers are added to the shell monomers, and the remaining monomers are supplemented with methyl methacrylate. This emulsion can still form a shear-responsive shell, but the affinity of the latex particles for the surface of inorganic particles such as colored sand is weakened.

[0050] Application testing The emulsions obtained in Examples 1-3 and Comparative Examples 1-3 were used to prepare stone-like paints. By weight, the stone-like paint could be formulated as follows: 80 parts deionized water, 3 parts dispersant, 2 parts wetting agent, 2 parts defoamer, 8 parts film-forming aid, 1 part preservative, 1.5 parts hydroxyethyl cellulose, 120 parts emulsion, 700 parts natural colored sand, and a suitable amount of pH adjuster. The amount of emulsion used in each group of stone-like paints was kept consistent, and they were prepared under the same stirring conditions.

[0051] The obtained stone-like paint was tested for storage stability, spraying continuity, anti-sagging, and coating appearance. During the test, spraying was carried out continuously for 30 minutes using a spray gun of the same diameter and under the same spraying pressure. The occurrence of phenomena such as gun clogging, material interruption, pulsed material discharge, spraying defects, and uneven distribution of sand particles was observed.

[0052] The test results are shown in Table 1: Table 1 The results above show that the stone-like paint emulsions obtained in Examples 1-3, when used in stone-like paint systems, can balance storage stability, spraying continuity, and anti-sagging properties. Compared with ordinary acrylic emulsions, this invention improves the spraying smoothness and uniformity of stone-like paint by setting a shear-responsive shell layer containing carboxylate structural units, phosphate structural units, long-chain alkyl polyether side chain structural units, and silane structural units on the outer layer of the latex particles. This allows the latex particles to provide better structural support under low shear conditions and reduce flow resistance under high shear conditions during spraying.

[0053] Compared to Comparative Example 2, which does not contain long-chain alkyl polyether acrylate monomers, Examples 1-3 exhibit better spray pressure stability and anti-sagging properties, indicating that the long-chain alkyl polyether side-chain structural units play an important role in forming reversible hydrophobic associative structures. Compared to Comparative Example 3, which does not contain phosphate-containing acrylate monomers, Examples 1-3 show more uniform sand particle distribution and less sedimentation tendency during storage, indicating that the phosphate structural units can enhance the interfacial affinity between latex particles and inorganic colored sand.

[0054] In summary, this invention does not simply rely on adding thickeners or thixotropic agents to improve the sprayability of stone paint. Instead, it uses the shell monomer design of core-shell structured latex particles to enable the emulsion itself to have shear response capability and inorganic particle affinity, thereby achieving a comprehensive effect in the stone paint system: static anti-settling, easy flow during spraying, anti-sagging after spraying, and uniform distribution of coating particles.

[0055] The above are merely preferred embodiments of the present invention. Those skilled in the art, inspired by the technical concept of the present invention, may make various adjustments and substitutions to the yarn material, weaving structure, cross angle, anchoring method, heat treatment conditions, and coating structure. All such adjustments and substitutions should be considered to fall within the protection scope of the present invention.

Claims

1. A stone-like paint emulsion that is easy to spray, characterized in that, It includes an aqueous phase and core-shell structured latex particles dispersed in the aqueous phase, wherein the core-shell structured latex particles include a flexible film-forming core layer and a shear-responsive shell layer covering the outside of the flexible film-forming core layer; Based on a total monomer mass of 100 parts, the core layer monomer forming the flexible film-forming core layer is 40 to 70 parts, and the shell monomer forming the shear-responsive shell layer is 30 to 60 parts. The shell monomers include methyl methacrylate, butyl acrylate, carboxyl-containing unsaturated monomers, phosphate-containing acrylate monomers, long-chain alkyl polyether acrylate monomers, and silane-coupled vinyl monomers. Wherein, the carboxyl units formed by the carboxyl-containing unsaturated monomers are at least partially neutralized to form carboxylate structural units, and the shear-response shell contains the carboxylate structural units, phosphate structural units, long-chain alkyl polyether side-chain structural units, and silane structural units.

2. The easy-to-spray stone paint emulsion according to claim 1, characterized in that, Based on a total mass of 100 parts of the core layer monomers, the core layer monomers include 40-65 parts of butyl acrylate, 5-25 parts of isooctyl acrylate, 20-45 parts of methyl methacrylate, and 0-15 parts of styrene.

3. The easy-to-spray stone paint emulsion according to claim 1, characterized in that, Based on a total mass of 100 parts of the shell monomers, the shell monomers include 35-65 parts of methyl methacrylate, 15-35 parts of butyl acrylate, 3-10 parts of methacrylic acid, 1-5 parts of acrylic acid, 1-6 parts of phosphate ester-containing acrylate monomers, 1-8 parts of long-chain alkyl polyether acrylate monomers, and 0.5-3 parts of silane-coupled vinyl monomers.

4. The easy-to-spray stone paint emulsion according to claim 1, characterized in that, The long-chain alkyl polyether acrylate monomer is at least one of dodecyl polyoxyethylene methacrylate, hexadecyl polyoxyethylene methacrylate, octadecyl polyoxyethylene methacrylate, dodecyl polyoxyethylene acrylate, hexadecyl polyoxyethylene acrylate, and octadecyl polyoxyethylene acrylate.

5. The easy-to-spray stone paint emulsion according to claim 1, characterized in that, The phosphate-containing acrylate monomer is at least one of hydroxyethyl methacrylate phosphate, hydroxyethyl acrylate phosphate, polyoxyethylene ether phosphate acrylate, and polyoxyethylene ether phosphate methacrylate. The silane-coupled vinyl monomer is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, methacryloyloxypropyltrimethoxysilane, and methacryloyloxypropyltriethoxysilane.

6. The easy-to-spray stone paint emulsion according to claim 1, characterized in that, The real stone paint emulsion also includes an emulsifier, which includes anionic emulsifiers and nonionic emulsifiers; The anionic emulsifier is at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium allyloxyhydroxypropyl sulfonate, and fatty alcohol polyoxyethylene ether sulfate. The nonionic emulsifier is at least one of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, and isomeric alcohol polyoxyethylene ether.

7. The easy-to-spray stone paint emulsion according to claim 1, characterized in that, The solid content of the real stone paint emulsion is 45-52%, the pH value is 7.5-8.8, the average particle size of the core-shell structured latex particles is 100-220 nm, and the mass ratio of the flexible film-forming core layer to the shear-responsive shell layer is 1:0.4-1:1.

2.

8. A method for preparing a sprayable stone paint emulsion as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Mix and pre-emulsify the core layer monomer, emulsifier and water to obtain the core layer pre-emulsion; S2. Mix and pre-emulsify the shell monomer, emulsifier and water to obtain a shell pre-emulsion, wherein the shell monomer includes methyl methacrylate, butyl acrylate, carboxyl-containing unsaturated monomer, phosphate ester-containing acrylate monomer, long-chain alkyl polyether acrylate monomer and silane-coupled vinyl monomer. S3. Add water, emulsifier and buffer to the reactor, heat up and add initiator and part of the core layer pre-emulsion to carry out seed polymerization to obtain seed latex particles; S4. Continue to add the remaining core layer pre-emulsion to the system containing the seed latex particles, so that a flexible film-forming core layer is formed on the outside of the seed latex particles; S5. After the flexible film-forming core layer is formed, the shell pre-emulsion is continued to be added dropwise to the reaction system, so that the shell monomers continue to polymerize on the outside of the flexible film-forming core layer to form a shear-responsive shell layer. S6. After the heat preservation reaction, the temperature is lowered, and an alkaline neutralizing agent is added to adjust the pH value so that the carboxyl units in the shear response shell are at least partially neutralized to form carboxylate structural units, thereby obtaining the real stone paint emulsion that is easy to spray.

9. The method for preparing the easy-to-spray stone paint emulsion according to claim 8, characterized in that, In step S3, the temperature for seed polymerization is 75–85°C; In step S4, the core layer pre-emulsion is added over a period of 1.5 to 3.5 hours. In step S5, the dropwise addition time of the shell pre-emulsion is 1 to 3 hours; In step S6, the alkaline neutralizing agent is at least one of ammonia, triethylamine, dimethylethanolamine, and 2-amino-2-methyl-1-propanol.

10. The method for preparing the easy-to-spray stone paint emulsion according to claim 8, characterized in that, In step S5, the shell pre-emulsion is added after the core pre-emulsion has been added and kept warm for 10-40 minutes; After the pre-emulsion in the shell layer is added, the reaction is continued at 75-85°C for 0.5-2 hours, and then the temperature is lowered to 40-50°C before adding the alkaline neutralizing agent.

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