High-flexibility sandstone paint and preparation method thereof

Abstract

The application provides a high-flexibility sandstone coating, which comprises the following components: 0.6-2 parts of protective glue, 0.05-0.3 parts of hydroxyl cellulose, 13.5-31 parts of modified acrylic emulsion, 6-14.5 parts of filler, 1.5-5.5 parts of auxiliary agent, and 26-54.5 parts of water-based solvent. The coating layer prepared from the high-flexibility sandstone coating has excellent flexibility and can still maintain excellent anti-cracking performance in an environment with large temperature difference.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of paint technology, and particularly relates to a high-flexibility sandstone paint and a preparation method thereof. BACKGROUND

[0002] Compared with the real stone paint, the sandstone paint can solve the defects of the real stone paint, and has the characteristics of good weather resistance, good stain resistance, good construction, high construction efficiency, high cost performance and the like, is suitable for the exterior wall decoration of high-rise building, hotel, villa and apartment, and is also suitable for the spraying decoration of prefabricated plate surface such as synthetic insulation board, integrated board and metal aluminum plate.

[0003] However, the coating prepared by the sandstone paint used in the market at present is prone to cracks due to the thermal expansion and cold shrinkage when used in the environment with large temperature difference, and loses the protection effect on the base material. Especially when used in the wall body with cracks in the component or surface, it is difficult to cover the surface defects.

[0004] Therefore, it is necessary to seek a paint which still has good flexibility and good decoration in the cold and hot alternating environment. SUMMARY

[0005] The present application aims to provide a high-flexibility sandstone paint and a preparation method thereof, and the coating prepared by the high-flexibility sandstone paint has excellent flexibility and still has excellent anti-cracking performance in the environment with large temperature difference.

[0006] According to the first aspect of the present application, a high-flexibility sandstone paint is provided, comprising the following components: 0.6-2 parts of protective glue, 0.05-0.3 parts of hydroxy cellulose, 13.5-31 parts of modified acrylic emulsion, 6-14.5 parts of filler, 1.5-5.5 parts of auxiliary agent, and 26-54.5 parts of water-based solvent; the modified acrylic emulsion is prepared by polymerization of hard acrylic monomer, soft acrylic monomer, and functional monomer; the hard acrylic monomer is at least one selected from methyl methacrylate and styrene, and the soft acrylic monomer is at least one selected from methyl acrylate, ethyl acrylate, and butyl acrylate; the functional monomer includes at least three of diacetone acrylamide, methacrylic acid, phosphate functional monomer, glycerol methacrylate, and acrylamide; the modified acrylic emulsion is prepared by the following steps: S1. preparing core monomer pre-emulsion and shell monomer pre-emulsion: uniformly mixing part of the hard acrylic monomer, part of the soft acrylic monomer, part of the functional monomer, and an emulsifier to prepare the core monomer pre-emulsion; uniformly mixing the remaining hard acrylic monomer, the remaining soft acrylic monomer, the remaining functional monomer, and an emulsifier to prepare the shell monomer pre-emulsion; S2. preparing core layer emulsion: uniformly mixing part of the core monomer pre-emulsion and an initiator at 75-80°C, and keeping the temperature until reflux appears in the reaction solution, then increasing the temperature of the reaction solution to 90-95°C and keeping the temperature; until blue light appears in the reaction solution, then decreasing the temperature of the reaction solution to 80-85°C, and dropping the first mixed solution into the reaction solution, the dropping time being 1-1.5 hours, the first mixed solution being prepared by mixing the remaining core monomer pre-emulsion and an initiator; after the dropping of the first mixed solution is completed, keeping the temperature of the reaction system at 80-85°C for 1-1.5 hours to prepare the core layer emulsion; S3. dropping the shell monomer pre-emulsion and an initiator into the core layer emulsion at 80-90°C, the dropping time being 1.25-1.75 hours, and keeping the temperature of the reaction system for 1-1.5 hours after the dropping is completed to prepare the modified acrylic emulsion.

[0007] The protective glue in the raw material of the high-flexibility sandstone paint provided by the present application has a gel reaction with the hydroxyethyl cellulose and the modified acrylic emulsion, so that colored particles can be prepared, and the stone-like effect can be achieved through the colored particles. The modified acrylic emulsion prepared from specific polymerized monomers is selected as the emulsion of the high-flexibility sandstone paint, which can effectively improve the film-forming performance of the colored particles prepared from the high-flexibility sandstone paint, reduce the possibility of color bleeding of the colored particles, and improve the flexibility of the coating prepared from the high-flexibility sandstone paint, so that the coating can still maintain excellent anti-cracking performance in an environment with large temperature difference.

[0008] The modified acrylic emulsion is prepared by selecting a core-shell polymerization method, which is beneficial to prepare the emulsion with small latex particle size and concentrated latex particle size distribution, and is convenient for large-scale production. In S3, the reaction process of the core layer emulsion and the shell monomer pre-emulsion is adjusted by adjusting the dropping speed of the shell monomer pre-emulsion and the initiator. If the dropping time is too long or the temperature during dropping is too high, the polymerization degree of the emulsion is too large, gel is generated, and side reactions are prone to occur. If the dropping time is too short or the temperature during dropping is too low, the reaction may not be complete. Moreover, by adding the core monomer pre-emulsion and the initiator in batches, the reaction temperature and the reaction process are more conducive to be controlled, thereby reducing the reaction failure rate. If the core monomer pre-emulsion and the initiator are added at one time in S2 to prepare the core layer emulsion, more heat is generated during the preparation process, it is difficult to control the reaction temperature, and gel is prone to occur in the core layer emulsion during the preparation process. Secondly, blue light appears in S2, which means that the main substance in the reaction system is the latex particle with a particle size distribution of 50-200 nm. Due to scattering, the latex particle will appear blue when the light passes through the latex particle in the particle size range.

[0009] Preferably, the emulsifier comprises an anionic emulsifier and a non-ionic emulsifier.

[0010] Preferably, the acrylic hard monomer is methyl methacrylate, the acrylic soft monomer is butyl acrylate, and the mass ratio of the acrylic hard monomer, the acrylic soft monomer and the functional monomer is 1-1.5:2-3:0.2-1. When methyl methacrylate is selected as the acrylic hard monomer, butyl acrylate is selected as the soft monomer, and the feeding ratio of the acrylic hard monomer, the acrylic soft monomer and the functional monomer is 1-1.5:2-3:0.2-1, the glass transition temperature of the prepared modified acrylic emulsion is in a suitable range, and the elasticity and brittleness of the prepared modified acrylic emulsion can be balanced, so that the coating prepared by the high-flexibility sandstone coating has good hardness, tensile strength and excellent flexibility, ductility and durability.

[0011] Preferably, the functional monomer comprises diacetone acrylamide, methacrylic acid and glyceryl methacrylate, and the molar ratio of diacetone acrylamide, methacrylic acid and glyceryl methacrylate is 1:1:1. The inventors find that when the functional monomers with the above specific ratio are used, the flexibility of the modified acrylic emulsion can be improved, the crack resistance and flexibility of the coating prepared by the high-flexibility sandstone coating under high and low temperature environments are further improved, and the possibility of cracking of the coating is reduced.

[0012] Preferably, the functional monomer further comprises ethoxyethyl ethylene urea methacrylate, and the molar ratio of diacetone acrylamide: ethoxyethyl ethylene urea methacrylate is 3-4:1. Through the inventor's repeated experiments, it is found that, on the basis of selecting diacetone acrylamide, methacrylic acid, and glycerol methacrylate as the modified monomer, adding a specific proportion of ethoxyethyl ethylene urea methacrylate to participate in polymerization can further improve the elasticity of the modified acrylic emulsion, and can also make the compatibility between the modified acrylic emulsion and materials such as quartz sand and hydroxyethyl cellulose better, thereby improving the dispersion performance of the high-flexibility sandstone paint during storage.

[0013] Preferably, the protective glue is a lithium magnesium silicate, and the hydroxy cellulose is hydroxyethyl cellulose. When the lithium magnesium silicate with a layered structure is used as the protective glue and the hydroxyethyl cellulose is used as the hydroxy cellulose, the toughness and strength of the colored particles prepared through the gel reaction of the protective glue, the hydroxy cellulose, and the modified acrylic emulsion during preparation can be improved, so that the colored particles can be uniformly and stably dispersed in the paint. Since the crystal structure unit of the lithium magnesium silicate is a micro-thin sheet with a thickness of several nanometers, water will be generated during the dispersion of the protective glue mixed with the aqueous solvent, and a large amount of aqueous solvent will penetrate into the lithium magnesium silicate in the sheet layer, which will expand the lithium magnesium silicate along the sheet until the sheets are separated from each other. Since the surface of the sheet has a negative charge and the end surface has a positive charge, under the action of the electrostatic repulsion and the intermolecular van der Waals force, the sheet will form a "card house" structure in the aqueous solvent. During the preparation of the paint, the protective glue with the "card house" structure and the hydroxyethyl cellulose with the hydroxy structure further gelatinize with the modified acrylic emulsion to form a semi-gelatinized protective layer with a thickness of 30-50 μm on the surface of the colored particles, so that the colored particles can stably exist in the protective glue solution, and the bleeding resistance of the high-flexibility sandstone paint is further improved. In addition, the protective glue, the hydroxyethyl cellulose, and the modified acrylic emulsion produce weak hydrogen bond crosslinking, thereby enhancing the flexibility of the coating.

[0014] Preferably, the filler comprises titanium white, kaolin, and quartz sand, and the quartz sand accounts for 86-98% of the filler. The quartz sand is used as the main filler of the high-flexibility sandstone paint, which can present a better stone-like effect with the colored particles.

[0015] Preferably, the quartz sand is modified quartz sand modified by an epoxy silane coupling agent. The modification reaction of the epoxy silane coupling agent with the quartz sand grafts an epoxy group onto the surface of the modified quartz sand, so that the prepared modified quartz sand has better suspension dispersion stability, thereby improving the material dispersion stability of the high-flexibility quartz sand paint. Moreover, the modified quartz sand grafted with the epoxy group can further cross-link with the modified acrylic emulsion having an amine group to form stable chemical bonds, thereby further increasing the adhesion between the modified quartz sand and the modified acrylic emulsion and the adhesion of the coating layer prepared from the high-flexibility quartz sand paint to the substrate.

[0016] Preferably, the modified quartz sand is prepared according to the following steps: first, uniformly mixing the quartz sand with toluene, then adding the epoxy silane coupling agent into the reaction system to obtain a first reaction liquid, and then reacting the first reaction liquid at 60-80℃ for 5.5-6.5 hours, precipitating, centrifuging, washing, and drying to obtain the modified quartz sand. The mass ratio of the quartz sand to the epoxy silane coupling agent is 15-20:1. This preparation method has mild conditions and simple operation, is conducive to large-scale production, and can reduce the cost of raw materials. Moreover, when the mass ratio of the quartz sand to the epoxy silane coupling agent is 15-20:1, the grafting rate of the quartz sand can be further improved. If the amount of the quartz sand is too large, the content of the epoxy silane coupling agent is too small, and the grafting rate of the modified quartz sand is small. If the amount of the quartz sand is too small, the content of the epoxy silane coupling agent is too large, and partial self-polymerization easily occurs, which also makes the grafting rate of the modified quartz sand small.

[0017] Preferably, the auxiliary agent includes a bactericide, a subsidence stabilizer, a dispersant, a wetting stabilizer, an antifoaming agent, an antifreezing agent, a film-forming auxiliary agent, a multifunctional auxiliary agent, propylene glycol, and a thickening agent.

[0018] Preferably, the subsidence stabilizer is at least one selected from modified bentonite, special xanthan gum, and modified cellulose ether.

[0019] Optionally, the titanium white is at least one selected from a product with a brand of BLR-698 produced by the Longmen Company and a rutile-type titanium white with a brand of ATR-311 produced by the Ananda Company.

[0020] Optionally, the wetting stabilizer is at least one selected from a product with a brand of G-399 produced by the Wangge Company, a product with a brand of DC809 produced by the Gresih Company, and a product with a brand of W-2520 produced by the Pufa Company.

[0021] Optionally, the hydroxyethyl cellulose is at least one selected from a product with a brand of BR30000H produced by the Yin Xiong Company, a product with a brand of EHM500 produced by the Akzo Nobel Company, and a product with a brand of 250HBR produced by the Ashland Company.

[0022] According to another aspect of the present application, a method for preparing the high-flexibility sandstone coating is provided, comprising the following steps: uniformly mixing protective glue, hydroxyl cellulose, part of modified acrylic emulsion, fillers, part of additives and part of water-based solvent, so that colored particles are generated in the reaction system; when the particle size of the colored particles reaches a preset target particle size, adding the remaining modified acrylic emulsion, the remaining additives and the remaining water-based solvent into the reaction system, and uniformly stirring to obtain the high-flexibility sandstone coating. The preparation method provided by the present application can adjust the particle size range of the colored particles according to market demand. Moreover, the preparation method has the advantages of simple preparation process, convenient operation, low cost, mild conditions and good economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The schematic diagram of the elongation at break of the coating prepared in Example 1 and the coating prepared in Comparative Example 1 is shown in the figure, and the corresponding relationship of the figure marks is as follows: 1 is Example 1, and 2 is Comparative Example 1. DETAILED DESCRIPTION

[0024] In order to enable personnel in the art to better understand the technical solutions in the present application, the technical solutions of the present application will be described clearly and completely in the following with reference to the accompanying drawings of the embodiments and examples of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0025] Example 1

[0026] The present embodiment provides a high-flexibility sandstone coating, and the specific preparation method is as follows:

[0027] (1) Preparation of modified acrylic emulsion

[0028] The preparation raw materials of the modified acrylic emulsion include: 15 parts of acrylic hard monomer, 25 parts of acrylic soft monomer, 10 parts of functional monomer, 1 part of anionic emulsifier, 3.5 parts of non-ionic emulsifier, 0.5 part of initiator, and 0.5 part of pH regulator. Among them, the acrylic hard monomer is methyl methacrylate (MMA), the acrylic soft monomer is butyl acrylate (BA), and the functional monomer is diacetone acrylamide (DAAM), methacrylic acid, glyceryl monomethacrylate, and ethylene urea methacrylate (UMA). According to the molar ratio, diacetone acrylamide:methacrylic acid:glyceryl monomethacrylate:ethylene urea methacrylate = 3:3:3:1.

[0029] The modified acrylic emulsion is prepared according to the following steps:

[0030] S1. Preparation of core monomer pre-emulsion and shell monomer pre-emulsion:

[0031] Take 1 / 2 of the acrylic hard monomer, 1 / 2 of the acrylic soft monomer, 1 / 2 of the functional monomer, and the emulsifier, mix uniformly, and prepare the core monomer pre-emulsion; mix the remaining acrylic hard monomer, the remaining acrylic soft monomer, the remaining functional monomer, and the emulsifier uniformly, and prepare the shell monomer pre-emulsion. In actual production application, the addition amount of acrylic hard monomer, acrylic soft monomer, anionic emulsifier, and non-ionic emulsifier in the core monomer pre-emulsion can be adjusted according to the actual situation.

[0032] S2. Preparation of core layer emulsion:

[0033] Mix 1 / 3 of the core monomer pre-emulsion with 1 / 3 of the initiator uniformly, and keep at 78℃ until the reaction solution appears backflow, then heat the reaction solution to 90℃ and keep; until blue light appears in the reaction solution, cool the reaction system to 85℃, and add the first mixed solution dropwise, the dropwise time is 1.5 hours, the first mixed solution is prepared by mixing the remaining 2 / 3 of the core monomer pre-emulsion with 1 / 3 of the initiator. After the first mixed solution is added, the reaction system is kept at 85℃ for 1 hour to prepare the core layer emulsion.

[0034] S3. At 85℃, add the shell monomer pre-emulsion and the remaining 1 / 3 of the initiator to the core layer emulsion, and the dropwise time is 1.5 hours. After the dropwise addition is completed, the reaction system is kept for 1 hour to prepare the modified acrylic emulsion.

[0035] (2) Preparation of modified quartz sand

[0036] The modified quartz sand is modified by an epoxy silane coupling agent, which is 3-(2,3-epoxypropoxy) propyl trimethoxysilane.

[0037] The modified quartz sand is prepared according to the following steps:

[0038] First, the quartz sand is mixed with toluene and ultrasonically dispersed for 30 minutes. Then, the epoxy silane coupling agent is added to the reaction system, and ultrasonic dispersion is continued for 5 minutes to obtain a first reaction liquid. The first reaction liquid is then reacted at 70°C for 6 hours, precipitated, centrifuged, washed, and dried to obtain the modified quartz sand. The mass ratio of the quartz sand to the epoxy silane coupling agent is 15:1.

[0039] (3) Preparation of high-flexibility sandstone paint

[0040] The raw materials for preparing the high-flexibility sandstone paint include the following components: 1.1 parts of protective glue, 0.3 parts of hydroxyl cellulose, 22 parts of modified acrylic emulsion, 30.3 parts of filler, 3.4 parts of auxiliary agent, and 26-54.5 parts of water-based solvent. The filler includes 27 parts of modified quartz sand, 0.6 parts of titanium dioxide, and 2.7 parts of kaolin. The auxiliary agent includes bactericide, anti-settling stabilizer, dispersant, wetting stabilizer, defoaming agent, antifreeze, film-forming aid, multifunctional auxiliary agent, propylene glycol, and thickening agent. In this embodiment, the amounts of the auxiliary agents can be adjusted according to actual conditions.

[0041] The high-flexibility sandstone paint is prepared according to the following steps:

[0042] The first mixed slurry containing protective glue is mixed with the second mixed slurry containing hydroxyl cellulose, part of the modified acrylic emulsion, filler, part of the auxiliary agent, and part of the water-based solvent. The reaction system is stirred uniformly at a dispersion speed of 1200 rpm to generate colored particles. When the particle size of the colored particles reaches the preset target particle size, the third mixed slurry is added to the reaction system. After stirring uniformly at a dispersion speed of 1000 rpm, the high-flexibility sandstone paint is prepared. The third mixed slurry contains the remaining modified acrylic emulsion, the remaining auxiliary agent, and the remaining water-based solvent.

[0043] The preparation operations of the first mixed slurry, the second mixed slurry, and the third mixed slurry are as follows: the first mixed slurry: part of the water-based solvent, part of the bactericide, and the anti-settling stabilizer are mixed and stirred at a speed of 500 rpm for 15 minutes. Then, part of the protective glue is added to the reaction system, and stirring is continued for 30 minutes to prepare the first mixed slurry.

[0044] The second mixed slurry: sequentially mixing part of the aqueous solvent, part of the bactericide, the anti-freezing agent, the dispersing agent, the wetting stabilizer, part of the defoaming agent, the titanium white, the calcined kaolin, the hydroxyethyl cellulose, and uniformly stirring at a speed of 1500 rpm for 15 minutes, adding the multifunctional additive, mixing uniformly, and preparing a premix slurry. Mixing the premix slurry with the remaining bactericide, the film-forming aid, the modified acrylic emulsion, and the remaining defoaming agent uniformly, adding the protective glue to the reaction system, mixing uniformly at a speed of 1500 rpm, and finally adding the modified quartz sand to prepare the second mixed slurry.

[0045] The third mixed slurry: sequentially mixing the water, the modified acrylic emulsion, the defoaming agent, the film-forming aid, the propylene glycol, the bactericide, the thickening agent, and the multifunctional additive uniformly to prepare the third mixed slurry.

[0046] Example 2

[0047] This example refers to the preparation method provided in Example 1 to prepare a high-flexibility sandstone paint. The difference between this example and Example 1 is that in the process of preparing the modified acrylic emulsion, the addition of ethylene urea methacrylate ethoxy ester is omitted. That is, diacetone acrylamide, methacrylic acid, and glyceryl methacrylate are selected as functional monomers, and the rest of the raw material ratio and the preparation method are strictly consistent with Example 1.

[0048] Example 3

[0049] This example refers to the preparation method provided in Example 1 to prepare a high-flexibility sandstone paint. The difference between this example and Example 1 is that in the process of preparing the modified acrylic emulsion, diacetone acrylamide is selected as the functional monomer, and the amount of diacetone acrylamide is consistent with the amount of functional monomers in Example 1. The rest of the raw material ratio and the preparation method are strictly consistent with Example 1.

[0050] Example 4

[0051] This example refers to the preparation method provided in Example 1 to prepare a high-flexibility sandstone paint. The difference between this example and Example 1 is that in the process of preparing the modified acrylic emulsion, methacrylic acid is selected as the functional monomer, and the amount of methacrylic acid is consistent with the amount of functional monomers in Example 1. The rest of the raw material ratio and the preparation method are strictly consistent with Example 1.

[0052] Example 5

[0053] This embodiment refers to the preparation method provided in embodiment 1 to prepare a high-flexibility sandstone paint. The difference between this embodiment and embodiment 1 is that in the process of preparing the modified acrylic emulsion, glyceryl methacrylate is selected as the functional monomer, and the amount of the functional monomer is consistent with that in embodiment 1. The remaining raw material ratio and preparation method are strictly consistent with those in embodiment 1.

[0054] Embodiment 6

[0055] This embodiment refers to the preparation method provided in embodiment 1 to prepare a high-flexibility sandstone paint. The difference between this embodiment and embodiment 1 is that in S3 of preparing the modified acrylic emulsion, the dropping temperature and time are adjusted. In this embodiment, the shell monomer pre-emulsion and initiator are added to the core layer emulsion at 80°C, and the dropping time is 1.75 hours. The remaining raw material ratio and preparation method are strictly consistent with those in embodiment 1.

[0056] Embodiment 7

[0057] This embodiment refers to the preparation method provided in embodiment 1 to prepare a high-flexibility sandstone paint. The difference between this embodiment and embodiment 1 is that in S3 of preparing the modified acrylic emulsion, the dropping temperature and time are adjusted. In this embodiment, the shell monomer pre-emulsion and initiator are added to the core layer emulsion at 90°C, and the dropping time is 1.25 hours. The remaining raw material ratio and preparation method are strictly consistent with those in embodiment 1.

[0058] Embodiment 8

[0059] This embodiment refers to the preparation method provided in embodiment 1 to prepare a high-flexibility sandstone paint. The difference between this embodiment and embodiment 1 is that the step of preparing modified quartz sand is omitted, and in the process of preparing the high-flexibility sandstone paint, equal mass of unmodified quartz sand is used instead of the modified quartz sand selected in embodiment 1. The remaining raw material ratio and preparation method are strictly consistent with those in embodiment 1.

[0060] Embodiment 9

[0061] This embodiment refers to the preparation method provided in embodiment 1 to prepare a high-flexibility sandstone paint. The difference between this embodiment and embodiment 1 is that in the process of preparing the modified quartz sand, the mass ratio of quartz sand to epoxy silane coupling agent is 10:1. The remaining raw material ratio and preparation method are strictly consistent with those in embodiment 1.

[0062] Embodiment 10

[0063] This example refers to the preparation method provided in Example 1 to prepare a high-flexibility sandstone paint. The difference between this example and Example 1 is that in the process of preparing the modified quartz sand, the mass ratio of quartz sand to epoxy silane coupling agent is 20:1. The remaining raw material ratio and preparation method are strictly the same as those of Example 1.

[0064] Example 11

[0065] This example refers to the preparation method provided in Example 1 to prepare a high-flexibility sandstone paint. The difference between this example and Example 1 is that in the process of preparing the modified quartz sand, the mass ratio of quartz sand to epoxy silane coupling agent is 25:1. The remaining raw material ratio and preparation method are strictly the same as those of Example 1.

[0066] Comparative Example 1

[0067] This comparative example refers to the preparation method provided in Example 1 to prepare a high-flexibility sandstone paint. The difference between this comparative example and Example 1 is that in the process of preparing the high-flexibility sandstone paint, equal mass of emulsion produced by Badefu Company with the trade name RS-9723A is used instead of the modified acrylic emulsion used in Components A and B in Example 1. The remaining raw material ratio and preparation method are strictly the same as those of Example 1.

[0068] Comparative Example 2

[0069] This comparative example refers to the preparation method provided in Example 1 to prepare a high-flexibility sandstone paint. The difference between this comparative example and Example 1 is that in the process of preparing the modified acrylic emulsion, all the core monomer pre-emulsion and initiator are mixed at one time to prepare the core layer emulsion. The specific operation is as follows: all the core monomer pre-emulsion and initiator are mixed uniformly at 78°C and kept until reflux appears in the reaction solution. The reaction solution is heated to 90°C and kept until blue light appears in the reaction solution. The reaction solution is cooled to 85°C and the reaction system is kept at 85°C for 1 hour to obtain the core layer emulsion. The remaining raw material ratio and preparation method are strictly the same as those of Example 1.

[0070] Comparative Example 3

[0071] This comparative example refers to the preparation method provided in Example 1 to prepare a high-flexibility sandstone paint. The difference between this comparative example and Example 1 is that in the process of preparing the modified acrylic emulsion, the dropping temperature and time are adjusted. In this comparative example, the shell monomer pre-emulsion and initiator are added to the core layer emulsion at 75°C, and the dropping time is 2 hours. The remaining raw material ratio and preparation method are strictly the same as those of Example 1.

[0072] Comparative Example 4

[0073] A high-flexibility sandstone paint was prepared according to the preparation method provided in Example 1. The difference between the present comparative example and Example 1 is that the dropping temperature and dropping time were adjusted in S3 for preparing the modified acrylic emulsion. In the present comparative example, the shell monomer pre-emulsion and initiator were dropped into the core layer emulsion at 95°C, and the dropping time was 1 hour. The rest of the raw material ratio and preparation method were strictly kept consistent with Example 1.

[0074] Test Example

[0075] Tested object: high-flexibility sandstone paints provided in Examples 1-11 and Comparative Examples 1-4.

[0076] Test item and test method:

[0077] (1) Storage stability: according to GB / T 6753.3-1986, the storage stability of the paint was detected after 1 month of storage, and whether the color particles had bleeding phenomenon was detected.

[0078] (2) Cold-heat cycle resistance: according to HG / T 0004-2012, the cold-heat cycle resistance of the coating prepared from the tested object was tested.

[0079] (3) Elongation at break: according to GB / T 528-2009, the elongation at break of the coating prepared from the tested object was tested.

[0080] (4) Adhesion to substrate: according to GB / T 9286-1998, the adhesion to substrate of the coating prepared from the tested object was tested.

[0081] Test results: the test results are shown in Table 1, and the comparison of the elongation at break of Example 1 and Comparative Example 1 is shown in Figure 1 Figure 1 1 in Table 1 is Example 1, and 2 is Comparative Example 1.

[0082] Table 1. Test performance corresponding to each tested object

[0083] Group Storage stability Cold heat cycle resistance Elongation at break Adhesion Example 1 No bleeding, no delamination Grade 1 210％ Grade 0 Example 2 No bleeding, no delamination Grade 1 180％ Grade 0 Example 3 No bleeding, no delamination Grade 1 150％ Grade 0 Example 4 No bleeding, no delamination Grade 1 145％ Grade 0 Example 5 No bleeding, no delamination Grade 1 130％ Grade 0 Example 6 No bleeding, no delamination Grade 1 190％ Grade 0 Example 7 No bleeding, no delamination Grade 1 200％ Grade 0 Example 8 No bleeding, no delamination Grade 1 170％ Grade 1 Example 9 No bleeding, no delamination Grade 1 150％ Grade 1 Example 10 No bleeding, no delamination Grade 1 180％ Grade 0 Example 11 No bleeding, no delamination Grade 1 150％ Grade 1 Comparative Example 1 No bleeding, no delamination Grade 1 30％ Grade 1 Comparative Example 2 / / / / Comparative Example 3 Bleeding, delamination Grade 2 110％ Grade 1 Comparative Example 4 Bleeding, delamination Grade 2 125％ Grade 1 Comparative Example 5 Bleeding, delamination Grade 2 Grade 1 Comparative Example 6 Bleeding, delamination Grade 2 Grade 1 Comparative Example 7 Bleeding, delamination Grade 2 Grade 1 Comparative Example 8 Bleeding, delamination Grade 2 Grade 1 Comparative Example 9 Bleeding, delamination Grade 2 Grade 1 Comparative Example 10 Bleeding, delamination Grade 2 Grade 1 Comparative Example 11 Bleeding, delamination Grade 2 Grade 1 Comparative Example 12 Bleeding, delamination Grade 2 Grade 1 Comparative Example 13 Bleeding, delamination Grade 2 Grade 1 Comparative Example 14 Bleeding, delamination Grade 2 Grade 1 Comparative Example 15 Bleeding, delamination Grade 2 Grade 1 Comparative Example 16 Bleeding, delamination Grade 2 Grade 1 Comparative Example 17 Bleeding, delamination Grade 2 Grade

[0084] Result analysis:

[0085] The high-flexibility sandstone paints prepared from Examples 1-11 and the paints prepared from Comparative Examples 1-4 were compared in terms of the test performance corresponding to each in Table 1. It can be seen that, compared with the paints and coatings of Comparative Examples 1-4, the paints of Examples 1-11 have better storage stability, and the coatings have better cold-heat cycle resistance, elongation at break, and adhesion to substrate.

[0086] ​Comparing the test data of examples 1-11 with the test data of comparative example 1, it can be seen that, compared with the coating corresponding to comparative example 1 prepared by using the commercially available emulsion, the elongation at break of the coating corresponding to examples 1-11 is larger and the coating is more resistant to cold and hot cycles, which indicates that the modified acrylic emulsion prepared by using the specific steps can make the prepared coating have higher flexibility and still maintain excellent anti-cracking performance in an environment with large temperature difference. In comparative example 2, the modified acrylic emulsion is not prepared by step-by-step synthesis, and in the process of preparing the modified acrylic emulsion, the mixed slurry for preparing the modified acrylic emulsion has a gel phenomenon, so the coating and the coating layer cannot be prepared.

[0087] Comparing the properties of comparative examples 3-4, example 1, and examples 6-7 in table 1, it can be seen that, with the increase of the dropping time and the decrease of the dropping temperature in S3 for preparing the modified acrylic emulsion, the elongation at break of the prepared coating presents a trend of first increasing and then decreasing, which indicates that, when the dropping temperature is 80-90℃ and the dropping time is 1.25-1.75h, the prepared modified acrylic emulsion can better improve the flexibility and the anti-cracking performance of the coating.

[0088] The above examples are only used to illustrate the technical solutions of the present application and not to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A high flexibility sandstone coating characterized in that, The protective glue 0.6-2 parts, hydroxyl cellulose 0.05-0.3 parts, modified acrylic emulsion 13.5-31 parts, filler 6-14.5 parts, auxiliary agent 1.5-5.5 parts, and water-based solvent 26-54.5 parts are included. The modified acrylic emulsion is prepared by polymerization of acrylic hard monomers, acrylic soft monomers, and functional monomers; the acrylic hard monomers are at least one selected from methyl methacrylate and styrene, the acrylic soft monomers are at least one selected from methyl acrylate, ethyl acrylate, and butyl acrylate; the functional monomers include diacetone acrylamide, methacrylic acid, and glyceryl methacrylate, and the molar ratio of diacetone acrylamide: methacrylic acid: glyceryl methacrylate is 1:1:1; the functional monomers also include methacrylic acid ethylene urea ethoxy ester, and the molar ratio of diacetone acrylamide: methacrylic acid ethylene urea ethoxy ester is 3-4:

1. The modified acrylic emulsion is prepared by the following steps: S1. Preparation of core monomer pre-emulsion and shell monomer pre-emulsion: uniformly mix part of the acrylic hard monomers, part of the acrylic soft monomers, part of the functional monomers, and an emulsifier to prepare the core monomer pre-emulsion; uniformly mix the remaining acrylic hard monomers, the remaining acrylic soft monomers, and the remaining functional monomers and an emulsifier to prepare the shell monomer pre-emulsion; S2. Preparation of core layer emulsion: uniformly mix part of the core monomer pre-emulsion and an initiator at 75-80°C, and keep warm until the reaction solution appears reflux; increase the temperature of the reaction solution to 90-95°C and keep warm; until blue light appears in the reaction solution, decrease the temperature of the reaction solution to 80-85°C, and drop the first mixed solution into the reaction solution, the dropping time is 1-1.5 hours, the first mixed solution is prepared by mixing the remaining core monomer pre-emulsion and the initiator; after the dropping of the first mixed solution is completed, keep the reaction system at a temperature of 80-85°C for 1-1.5 hours to prepare the core layer emulsion; S3. At 80-90°C, drop the shell monomer pre-emulsion and the initiator into the core layer emulsion, the dropping time is 1.25-1.75 hours, and after the dropping is completed, keep the reaction system for 1-1.5 hours to prepare the modified acrylic emulsion.

2. The high flexibility sandstone coating as claimed in claim 1, wherein, The acrylic hard monomers are methyl methacrylate, and the acrylic soft monomers are butyl acrylate, and the mass ratio of the acrylic hard monomers: the acrylic soft monomers: the functional monomers is 1-1.5:2-3:0.2-1.

3. The high flexibility sandstone coating as claimed in claim 1, wherein, The protective glue is lithium magnesium silicate, and the hydroxyl cellulose is hydroxyethyl cellulose.

4. The high flexibility sandstone coating as claimed in claim 1, wherein, The filler includes titanium white, kaolin, and quartz sand, and the quartz sand accounts for 86-98% in the filler.

5. The high flexibility sandstone coating as claimed in claim 4, wherein, The quartz sand is modified quartz sand modified by an epoxy silane coupling agent.

6. The high flexibility sandstone coating as claimed in claim 5, wherein, The modified quartz sand is prepared by the following steps: The quartz sand is mixed with toluene, and then an epoxy silane coupling agent is added to the reaction system to obtain a first reaction liquid, and the first reaction liquid is reacted at 60-80℃ for 5.5-6.5 hours, precipitated, centrifuged, washed and dried to obtain the modified quartz sand, wherein the mass ratio of the quartz sand to the epoxy silane coupling agent is 15-20:

1.

7. The high flexibility sandstone coating as claimed in claim 1, wherein, The auxiliary agents include bactericides, anti-settling stabilizers, dispersants, wetting stabilizers, antifoaming agents, antifreezing agents, film-forming aids, multifunctional aids, propylene glycol and thickening agents.

8. A process for the preparation of a high flexibility sandstone coating as claimed in any one of claims 1 to 7, characterized in that, The method comprises the following steps: The protective glue, the hydroxyl cellulose, part of the modified acrylic emulsion, the filler, part of the auxiliary agent and part of the water-based solvent are mixed uniformly to generate colored particles in the reaction system, and when the particle size of the colored particles reaches a preset target particle size, the remaining modified acrylic emulsion, the remaining auxiliary agent and the remaining water-based solvent are added to the reaction system, and the high-flexibility sandstone coating is prepared after uniform stirring.

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