High light purity acrylic emulsion

Abstract

According to one aspect of the present application, a high light purity acrylic emulsion is provided, raw materials for preparing the high light purity acrylic emulsion include acrylate monomers, crosslinking monomers, carboxyl monomers, emulsifiers and initiators, the acrylate monomers include acrylate hard monomers and acrylate soft monomers, the T g value of the acrylate hard monomers is 15-110℃, the T g value of the acrylate soft monomers is -80- -60℃; and a preparation method of the high light purity acrylic emulsion includes the following steps: S1. preparing a core layer pre-emulsion and a shell layer pre-emulsion; S2. adding emulsifiers into water to obtain a first reaction liquid, and heating to 80-85℃, then adding initiators, the core layer pre-emulsion into the first reaction liquid to obtain a second reaction liquid; S3. adding the shell layer pre-emulsion into the second reaction liquid dropwise, during which, adding crosslinking monomers and carboxyl monomers into the reaction system; S4. after S3 is completed, adding other additives into the reaction system to obtain the high light purity acrylic emulsion.

Description

Technical Field

[0001] This invention belongs to the field of latex technology, and particularly relates to a high-gloss pure acrylic emulsion. Background Technology

[0002] With the rapid development of pure acrylic emulsion paint technology for exterior walls, a wide variety of exterior wall products have emerged. However, problems such as difficult construction, poor water resistance and whitening, poor stain resistance, and low gloss also exist.

[0003] On the one hand, existing pure acrylic emulsion paints for exterior walls are mostly applied manually, inevitably leading to uneven paint application. This results in paint films of varying thicknesses and densities, causing uneven gloss and a mottled appearance. Furthermore, current paints require specific application techniques, such as roller or spray application, to prevent issues like patchy finishes.

[0004] On the other hand, existing pure acrylic emulsion paints for exterior walls tend to soften and become sticky when heated, or soften when soaked in rainwater. The softened paint film is more likely to absorb pollutants from the air. Rainwater carries dust from the air onto the paint film surface, and because the paint film is not water-resistant and has surface pores, tiny pollutants can penetrate into the coating with the rainwater. After the water evaporates, the pollutants remain inside the paint film, forming permanent pollution. This leads to problems such as dirt and discoloration on the paint film, reducing the aesthetic appeal of the exterior wall. Summary of the Invention

[0005] In order to reduce the difficulty of emulsion application and improve the gloss, water resistance and stain resistance of emulsion, the present invention aims to provide a high-gloss pure acrylic emulsion.

[0006] According to one aspect of the present invention, a high-gloss pure acrylic emulsion is provided, characterized in that: the raw materials used to prepare the high-gloss pure acrylic emulsion include acrylate monomers, crosslinking monomers, carboxyl monomers, emulsifiers, and initiators; the acrylate monomers include hard acrylate monomers and soft acrylate monomers; and the T of the hard acrylate monomers... g The value is 15℃~110℃, and the T value of acrylate soft monomers is... gThe temperature range is -80℃ to -60℃. The preparation method of high-gloss pure acrylic emulsion includes the following steps: S1. Prepare the core layer pre-emulsion and shell layer pre-emulsion separately. The core layer pre-emulsion, calculated by mass parts, includes 3-10 parts of acrylate hard monomers, 3-7 parts of acrylate soft monomers, 0-0.5 parts of crosslinking monomers, 0.1-1 parts of carboxyl monomers, 0.5-1 parts of emulsifier, and 0.1-0.3 parts of initiator. The shell layer pre-emulsion includes 12-24 parts of acrylate hard monomers, 2-4 parts of acrylate soft monomers, 0.9-1.5 parts of emulsifier, and 0.1-0.3 parts of initiator. S1. Add 0.5-1 part of emulsifier to 25-35 parts of water by mass to obtain the first reaction solution. Heat the first reaction solution to 80-85℃, then add 0.1-0.3 parts of initiator to it, and then add the core layer pre-emulsion to the reaction system to obtain the second reaction solution; S2. Add the shell layer pre-emulsion to the second reaction solution. During this process, add 1-3 parts of crosslinking monomer and 0.5-2 parts of carboxyl monomer to the reaction system by mass; S3. After S4 is completed, add other additives to the reaction system to obtain a high-gloss acrylic emulsion.

[0007] This invention utilizes a clever and unique core-shell emulsion polymerization method to produce pure acrylic emulsions with good gloss, water resistance, and stain resistance. Furthermore, its application is relatively simple, allowing for spraying or roller coating, and it addresses the issue of blooming in high-gloss emulsions. On one hand, this invention, through appropriate T... g The range of acrylate hard monomers and acrylate soft monomers reduces the use of hard acrylate monomers, resulting in a softer core layer and a harder shell layer. This increases the film-forming temperature of the emulsion and the hardness of the paint film, further improving the stain resistance of the paint film while ensuring that the paint film does not crack under temperature changes and thick coating conditions. On the other hand, through a special process, emulsifiers, crosslinking monomers, and carboxylic acid monomers can be cleverly distributed between the core and shell layers, giving the paint film excellent sealing properties. This slows down the rate at which water permeates through the topcoat, enhancing the water resistance and water-whitening resistance of the paint film.

[0008] Preferably, the acrylate hard monomers include hard monomer I and hard monomer II, wherein the T of hard monomer I is... g The value is 95℃~105℃, and the T value of hard monomer II is... g The value is 10℃~30℃. By further limiting the Tg distribution of the hard monomers, the hard and soft monomers used in this scheme form a specific range of Tg values. g Poor performance can further increase the film-forming temperature of the emulsion, thereby enhancing the hardness and stain resistance of the emulsion.

[0009] Preferably, the mass ratio is calculated as follows: in the core preemulsion, hard monomer I: hard monomer II = 2~6: 1~4; in the shell preemulsion, hard monomer I: hard monomer II = 9~18: 3~6.

[0010] Preferably, the soft monomer comprises isooctyl acrylate. The T of isooctyl acrylate... g The temperature is -54℃.

[0011] Preferably, hard monomer I comprises methyl methacrylate. The T of methyl methacrylate... g It is 104℃.

[0012] Preferably, hard monomer II comprises butyl methacrylate. The T of butyl methacrylate... g The temperature is 21℃, and the addition of butyl methacrylate to the core and shell pre-emulsions can improve the film-forming properties of the emulsion and the flexibility of the paint film.

[0013] Preferably, the crosslinking monomer includes at least one selected from acrylamide, methacrylamide, glycidyl methacrylate, and ethyl acetoacetate methacrylate. The amide group can enhance the stain resistance of the emulsion.

[0014] Preferably, the carboxyl monomer includes at least one of acrylic acid, methacrylic acid, itaconic acid, and maleic acid.

[0015] Preferably, the initiator includes at least one of ammonium persulfate, potassium persulfate, and sodium persulfate.

[0016] Preferably, the raw materials used to prepare the high-gloss pure acrylic emulsion also include organosilicon monomers. Calculated by mass parts, the core layer pre-emulsion includes 0.1 to 1 part organosilicon monomers, and the shell layer pre-emulsion includes 0.8 to 1.5 parts organosilicon monomers. The long- and short-chain crosslinking reactions and copolymerization reactions between organosilicon monomers can improve the degree of crosslinking of the emulsion, thereby enhancing the density and water-whitening resistance of the coating film.

[0017] Preferably, the organosilicon monomer includes at least one of vinyltrimethoxysilane, vinyltriethoxysilane, methacryloxypropyltrimethoxysilane, and vinyltris(β-methoxyethoxy)silane.

[0018] Preferably, the emulsifier includes at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium dodecyl diphenyl ether disulfonate, fatty alcohol polyoxyethylene ether, alkyl polyoxyethylene ether, isooctyl alcohol polyoxyethylene ether phosphate, sodium 3-allyloxy-2-hydroxy-1-propane sulfonate, sodium 2-acrylamido-2-methylpropane sulfonate, Adico SR-10, and Adico SR-20. By combining a suitable emulsifier, the surface tension of the paint film can be further reduced, improving the unevenness problem that occurs during application.

[0019] Preferably, the emulsifier used in the preparation of the shell pre-emulsion includes isooctyl alcohol polyoxyethylene ether phosphate. By optimizing the process and introducing an emulsifier containing phosphate groups, the phosphate ester is allowed to aggregate on the surface of the paint film formed by the pure acrylic emulsion provided by this invention, thereby further improving the stain resistance of the paint film.

[0020] Preferably, in step S4: the additives added to the reaction system include a pH adjuster and a film-forming aid; the amount of pH adjuster added is sufficient to make the pH value of the high-gloss pure acrylic emulsion 6.5~8.5; the film-forming aid includes at least one of propylene glycol ester dodecyl, propylene glycol phenyl ether, propylene glycol butyl ether, and Dow COASOL, and the amount of film-forming aid added is sufficient to make the minimum film-forming temperature of the high-gloss pure acrylic emulsion 30~45°C. The film-forming aid can stabilize the film-forming state of the emulsion, and thus work with propylene ester monomers to regulate the film-forming temperature and film-forming effect of the emulsion.

[0021] Preferably, the pH adjuster includes at least one of ammonia, sodium hydroxide, potassium hydroxide, and Dow AMP-95.

[0022] Preferably, in S2, the core layer pre-emulsion is added to the reaction system over a period of 0.5 to 1 hour, and after the addition is complete, the mixture is kept warm for another 0.3 to 1 hour to obtain the second reaction solution; in S3, the shell layer pre-emulsion is added to the second reaction solution over a period of 3.5 to 4.5 hours, and after the addition is complete, the mixture is kept warm for another 0.5 to 1.5 hours.

[0023] Preferably, in S3, the dropping time of the shell preemulsion is divided into a first time period and a second time period, the duration of the first time period and the second time period are equal; S3 includes the following operations: a. During the first time period, a portion of the shell preemulsion is dropped into the second reaction solution; b. After the first time period ends, the dropping of the shell preemulsion is stopped, and crosslinking monomers and carboxyl monomers are added to the reaction system to fully disperse them in the reaction system; c. During the second time period, the remaining shell preemulsion is dropped into the reaction system.

[0024] Preferably, mechanical stirring is maintained throughout the preparation method described above.

[0025] Therefore, this invention discloses a high-gloss pure acrylic emulsion, which has at least the following advantages: First, by selecting suitable acrylate hard monomers and acrylate soft monomers, an emulsion with a high film-forming temperature is synthesized, increasing the hardness of the paint film while ensuring no cracking due to temperature changes and thick coatings, thus improving the problem of easy softening of the paint film when heated in the prior art. Second, by selecting a suitable emulsification system, the emulsifier is rationally distributed between the core and shell layers of the emulsion, which can give the paint film excellent water resistance and water-whitening resistance. At the same time, the synergistic effect of the emulsification system and various additives in the synthesis process gives the pure acrylic emulsion both ultra-low surface tension and high penetration performance. After construction, it can significantly improve the problem of uneven thickness of wall application leading to color blooming, and reduce the difficulty of emulsion construction. Third, by adjusting the process to regulate the aggregated distribution of functional groups such as carboxylic acids, amides, and phosphate esters near the surface of the shell layer, the surface of the paint film is like a "brush". When the paint film comes into contact with water, it quickly wets the surface and removes stains, giving the paint film a self-cleaning function and ensuring that the paint film remains like new for a long time. Finally, the high-gloss pure acrylic emulsion prepared by this invention has excellent properties such as water resistance, water whitening resistance, stain resistance, and yellowing resistance. It also has good stability, versatility, and high permeability, and can effectively solve the problem of color blooming during construction. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0027] Example 1

[0028] 1. Raw material preparation for pure acrylic emulsion

[0029] This embodiment provides a pure acrylic emulsion. The raw materials and their mass fractions required to prepare the pure acrylic emulsion are shown in Table 1. The additives used in this embodiment to prepare the pure acrylic emulsion include the film-forming agent and pH adjuster mentioned in Table 1.

[0030] Table 1. Raw materials required for preparing pure acrylic emulsion in this embodiment.

[0031]

[0032] 2. Method for preparing pure acrylic emulsion

[0033] S1. After preparing the required raw materials according to Table 1, prepare the core layer preemulsion and shell layer preemulsion separately. Specifically, according to the mass parts, take 2 parts of methyl methacrylate, 5 parts of isooctyl acrylate, 1 part of butyl methacrylate, 0.5 parts of acrylamide, 0.3 parts of methacrylic acid, 0.5 parts of vinyltrimethoxy, 0.5 parts of Adico SR-10, 0.5 parts of sodium dodecyl sulfate, 0.2 parts of ammonium persulfate, and 10 parts of deionized water to prepare the core layer preemulsion; mix the remaining methyl methacrylate, remaining isooctyl acrylate, remaining butyl methacrylate, 1.5 parts of vinyltrimethoxysilane, 0.5 parts of Adico SR-10, 0.5 parts of isooctyl alcohol polyoxyethylene ether phosphate, 0.5 parts of sodium 2-acrylamido-2-methylpropanesulfonate, 0.5 parts of ammonium persulfate, and 20 parts of deionized water to prepare the shell layer preemulsion.

[0034] S2. Calculate by mass parts, add 0.5 parts of sodium dodecylbenzenesulfonate 2 to the remaining deionized water in the raw materials to obtain the first reaction solution. Heat the first reaction solution to 80°C, then add 0.3 parts of ammonium persulfate to it, and then add the core layer pre-emulsion dropwise to the reaction system over a period of 0.5 hours. After the addition is complete, continue to keep it warm for another 0.5 hours to obtain the second reaction solution.

[0035] S3. Add shell pre-emulsion dropwise to the second reaction solution over a period of 2 hours. Stop adding shell pre-emulsion dropwise and add 0.7 parts of methacrylic acid and 1.5 parts of glycidyl methacrylate to the reaction system. After dispersing for 10 minutes, add the remaining shell pre-emulsion dropwise to the reaction system over a period of 2 hours. After the addition is complete, continue to keep warm for 1 hour.

[0036] S4. After completing S3, cool down to 50℃, add 1 part ammonia water to adjust the pH of the emulsion to between 6.5 and 8.5, then slowly add 3 parts of alcohol ester twelve, keep the temperature at 50℃, stir for 0.5 hours, and a high-gloss pure acrylic emulsion is obtained.

[0037] Example 2

[0038] 1. Raw material preparation for pure acrylic emulsion

[0039] This embodiment provides a pure acrylic emulsion. The raw materials and formulations required for preparing the pure acrylic emulsion are shown in Table 2. The additives used in this treatment group to prepare the pure acrylic emulsion include the film-forming agent and pH adjuster mentioned in Table 2.

[0040] Table 2. Raw materials required for preparing pure acrylic emulsion in this embodiment.

[0041]

[0042] 2. Method for preparing pure acrylic emulsion

[0043] S1. After preparing the required raw materials according to Table 2, prepare the core layer preemulsion and shell layer preemulsion separately. Specifically, according to the mass parts, take 4 parts methyl methacrylate, 3 parts isooctyl acrylate, 4 parts butyl methacrylate, 1 part methacrylic acid, 0.1 parts vinyltrimethoxysilane, 0.3 parts Adico SR-20, 0.3 parts sodium dodecyl sulfate, 0.1 parts ammonium persulfate, and 5 parts deionized water to prepare the core layer preemulsion; mix the remaining methyl methacrylate, remaining isooctyl acrylate, remaining butyl methacrylate, 0.9 parts methacryloxypropyltrimethoxysilane, 0.4 parts Adico SR-20, 0.2 parts fatty alcohol polyoxyethylene ether, 0.3 parts sodium 2-acrylamido-2-methylpropanesulfonate, 0.2 parts ammonium persulfate, and 15 parts deionized water to prepare the shell layer preemulsion.

[0044] S2. Calculate by mass parts, add 0.3 parts sodium dodecylbenzenesulfonate and 0.2 parts fatty alcohol polyoxyethylene ether to the remaining deionized water in the raw materials to obtain the first reaction solution. Heat the first reaction solution to 80°C, then add 0.2 parts ammonium persulfate to it, and then add the core layer pre-emulsion dropwise to the reaction system over a period of 0.5 hours. After the dropwise addition is complete, continue to keep it warm for another 0.5 hours to obtain the second reaction solution.

[0045] S3. Add shell pre-emulsion dropwise to the second reaction solution over a period of 2 hours. Stop adding shell pre-emulsion dropwise and add 2 parts acrylic acid and 1 part methacrylamide to the reaction system. After dispersing for 10 minutes, add the remaining shell pre-emulsion dropwise to the reaction system over a period of 2 hours. After the addition is complete, continue to keep warm for 1 hour.

[0046] S4. After completing S3, cool down to 50°C, add 3 parts ammonia water to adjust the pH of the emulsion to between 7 and 7. Then slowly add 2 parts Dow COASOL, keep the temperature at 50°C, and stir for 0.5 hours to obtain a high-gloss pure acrylic emulsion.

[0047] Example 3

[0048] 1. Raw material preparation for pure acrylic emulsion

[0049] This embodiment provides a pure acrylic emulsion. The raw materials and formulations required for preparing the pure acrylic emulsion are shown in Table 3. The additives used in this treatment group to prepare the pure acrylic emulsion include the initiator, film-forming agent, and pH adjuster mentioned in Table 3.

[0050] Table 3. Raw materials required for preparing pure acrylic emulsion in this embodiment.

[0051]

[0052] 2. Method for preparing pure acrylic emulsion

[0053] S1. After preparing the required raw materials according to Table 3, prepare the core layer preemulsion and shell layer preemulsion separately. Specifically, according to the mass parts, take 2 parts of methyl methacrylate, 7 parts of isooctyl acrylate, 2 parts of butyl methacrylate, 1 part of methacrylic acid, 0.2 parts of vinyltrimethoxysilane, 0.2 parts of Adico SR-10, 0.4 parts of sodium dodecyl sulfate, 0.2 parts of sodium persulfate, and 7 parts of deionized water to mix and prepare the core layer preemulsion; take the remaining methyl methacrylate, the remaining isooctyl acrylate, the remaining butyl methacrylate, 0.4 parts of vinyltrimethoxysilane, 0.4 parts of vinyltris(β-methoxyethoxy)silane, 0.4 parts of Adico SR-10, 0.3 parts of isooctyl alcohol polyoxyethylene ether phosphate, 0.2 parts of sodium 3-allyloxy-2-hydroxy-1-propanesulfonate, 0.4 parts of sodium persulfate, and 9 parts of deionized water to mix and prepare the shell layer preemulsion.

[0054] S2. Calculate by mass parts, add 0.4 parts sodium dodecyl sulfate and 0.1 parts alkyl polyoxyethylene ether to the remaining deionized water in the raw materials to obtain the first reaction solution. Heat the first reaction solution to 80°C, then add 0.4 parts sodium persulfate to it, and then add the core layer pre-emulsion dropwise to the reaction system over a period of 0.5 hours. After the dropwise addition is complete, continue to keep it warm for another 0.5 hours to obtain the second reaction solution.

[0055] S3. Add shell pre-emulsion dropwise to the second reaction solution over a period of 2 hours. Then, stop adding shell pre-emulsion and add 1 part itaconic acid, 0.5 parts methacrylamide, and 0.5 parts ethyl acetoacetate to the reaction system. After dispersing for 10 minutes, add the remaining shell pre-emulsion dropwise to the reaction system over a period of 2 hours. After the addition is complete, continue to keep the system warm for 1 hour.

[0056] S4. After completing S3, cool down to 50°C, add 1 part of Dow AMP-95 to adjust the pH of the emulsion to around 7, then slowly add 4 parts of propylene glycol butyl ether, keep the temperature at 50°C, stir for 0.5 hours, and a high-gloss pure acrylic emulsion is obtained.

[0057] Example 4

[0058] 1. Raw material preparation for pure acrylic emulsion

[0059] This embodiment provides a pure acrylic emulsion. The raw materials and formulations required for preparing the pure acrylic emulsion are shown in Table 4. The additives used in this treatment group to prepare the pure acrylic emulsion include the initiator, film-forming agent, and pH adjuster mentioned in Table 4.

[0060] Table 4. Raw materials required for preparing pure acrylic emulsion in this embodiment.

[0061]

[0062] 2. Method for preparing pure acrylic emulsion

[0063] S1. After preparing the required raw materials according to Table 4, prepare the core layer preemulsion and shell layer preemulsion separately. Specifically, according to the mass parts, take 6 parts of methyl methacrylate, 6 parts of isooctyl acrylate, 3 parts of butyl methacrylate, 0.5 parts of methacrylamide, 0.5 parts of methacrylic acid, 0.5 parts of vinyltrimethoxysilane, 0.5 parts of Adico SR-10, 0.2 parts of potassium persulfate, and 10 parts of deionized water to prepare the core layer preemulsion. Mix the remaining methyl methacrylate, remaining isooctyl acrylate, remaining butyl methacrylate, 1.5 parts of methacryloxypropyltrimethoxysilane, 0.3 parts of Adico SR-10, 0.2 parts of sodium dodecylbenzene sulfonate, 0.2 parts of isooctyl alcohol polyoxyethylene ether phosphate, 0.3 parts of 2-acrylamido-2-methylpropanesulfonate, 0.5 parts of potassium persulfate, and 20 parts of deionized water to prepare the shell layer preemulsion.

[0064] S2. Calculate by mass parts, add 0.5 parts of sodium dodecyl sulfate to the remaining deionized water in the raw materials to obtain the first reaction solution. Heat the first reaction solution to 80°C, then add 0.3 parts of potassium persulfate to it, and then add the core layer pre-emulsion dropwise to the reaction system over a period of 0.5 hours. After the addition is complete, continue to keep it warm for another 0.5 hours to obtain the second reaction solution.

[0065] S3. Add shell pre-emulsion dropwise to the second reaction solution over a period of 2 hours. Stop adding shell pre-emulsion dropwise and add 1.5 parts methacrylic acid and 1.5 parts acrylamide to the reaction system. After dispersing for 10 minutes, add the remaining shell pre-emulsion dropwise to the reaction system over a period of 2 hours. After the addition is complete, continue to keep warm for 1 hour.

[0066] S4. After completing S3, cool down to 50℃, add 1 part ammonia water to adjust the pH of the emulsion to between 7 and 7, then slowly add 2 parts of alcohol ester dodecyl, keep the temperature at 50℃, stir for 0.5 hours, and a high-gloss pure acrylic emulsion is obtained.

[0067] Example 5

[0068] 1. Raw material preparation for pure acrylic emulsion

[0069] This embodiment provides a pure acrylic emulsion. The raw materials and formulations required for preparing the pure acrylic emulsion are shown in Table 5. The additives used in this treatment group to prepare the pure acrylic emulsion include the initiator, film-forming agent, and pH adjuster mentioned in Table 5.

[0070] Table 5. Raw materials required for preparing pure acrylic emulsion in this embodiment.

[0071]

[0072] 2. Method for preparing pure acrylic emulsion

[0073] S1. After preparing the required raw materials according to Table 5, prepare the core layer preemulsion and shell layer preemulsion separately. Specifically, according to the mass parts, take 3 parts methyl methacrylate, 4 parts isooctyl acrylate, 2 parts butyl methacrylate, 0.5 parts methacrylic acid, 0.5 parts vinyltrimethoxysilane, 0.3 parts sodium dodecyl sulfate, 0.5 parts sodium dodecylbenzene sulfonate, 0.1 parts ammonium persulfate, and 5.5 parts deionized water to prepare the core layer preemulsion; mix the remaining methyl methacrylate, remaining isooctyl acrylate, remaining butyl methacrylate, 1.5 parts vinyltriethoxysilane, 0.6 parts sodium dodecylbenzene sulfonate, 0.5 parts isooctyl alcohol polyoxyethylene ether phosphate, 0.3 parts 2-acrylamido-2-methylpropanesulfonate, 0.6 parts ammonium persulfate, and 15 parts deionized water to prepare the shell layer preemulsion.

[0074] S2. Calculate by mass parts, add 0.5 parts sodium dodecyl sulfate and 0.3 parts isooctanol polyoxyethylene ether phosphate to the remaining deionized water in the raw materials to obtain the first reaction solution. Heat the first reaction solution to 80°C, then add 0.3 parts ammonium persulfate to it, and then add the core layer pre-emulsion dropwise to the reaction system over a period of 0.5 hours. After the dropwise addition is complete, continue to keep it warm for another 0.5 hours to obtain the second reaction solution.

[0075] S3. Add shell pre-emulsion dropwise to the second reaction solution over a period of 2 hours. Then, stop adding shell pre-emulsion and add 0.5 parts methacrylic acid, 2 parts acrylamide, and 1 part glycidyl methacrylate to the reaction system. After dispersing for 10 minutes, add the remaining shell pre-emulsion dropwise to the reaction system over a period of 2 hours. After the addition is complete, continue to keep the system warm for 1 hour.

[0076] S4. After completing S3, cool down to 50℃, add 2.5 parts of 10% sodium hydroxide solution to adjust the pH of the emulsion to around 7, then slowly add 2 parts of alcohol ester dodecyl, keep the temperature at 50℃, stir for 0.5 hours, and a high-gloss pure acrylic emulsion is obtained.

[0077] Example 6

[0078] This comparative example prepares pure acrylic emulsion according to the proportions and methods of Example 1. The difference from Example 1 is that no organosilicon is added during the preparation process. Apart from the above differences, the operation and steps for preparing pure acrylic emulsion in this comparative example are strictly consistent with those in Example 1.

[0079] Test Example 1

[0080] 1. Preparation of water-based high-gloss topcoat varnish

[0081] The emulsions prepared in Examples 1-6 were formulated into varnishes according to the formulations shown in Table 6. Subsequently, the formulated water-based high-gloss topcoat varnishes were tested on a substrate.

[0082] Table 6. Water-based high-gloss clear coat formulation

[0083]

[0084] 2. Testing Methods

[0085] (1) Emulsion particle size: The prepared emulsion was tested using a Malvern laser particle size analyzer;

[0086] (2) Viscosity: The prepared emulsion was tested using a HAKKE rotational viscometer;

[0087] (3) Minimum film-forming temperature: The prepared emulsion was tested using a Jingke QMB-II minimum film-forming temperature tester;

[0088] (4) Surface tension of the emulsion: The prepared emulsion was tested using a German KRUSS surface tension tester;

[0089] (5) Stain resistance: The varnish was tested according to the standard of HG / T 5065-2016 "Topcoat Varnish for Architectural Coatings". The stain resistance was tested using method B. The lower the reduction rate coefficient, the better the performance.

[0090] (6) Water resistance and water whitening performance: The varnish was tested according to the standard of HG / T 5065-2016 "Topcoat Varnish for Architectural Coatings" on a multicolor paint substrate, and the bubbling and discoloration were observed.

[0091] (7) Gloss: The varnish was tested according to GB / T9754-2007 "Determination of 20°, 60° and 85° specular gloss of paint film without metallic pigments". During the test, the axis of the incident beam was at 60° to the normal of the test surface.

[0092] 3. Results and Analysis

[0093] 3.1 Test results and analysis of the prepared emulsion

[0094] The test results of the prepared emulsions are shown in Table 7. The emulsions prepared in Examples 1-4 simultaneously meet the following requirements: solid content of 37-42%, particle size of 60-100 nm, viscosity below 1000 CPS (3#30r), minimum film-forming temperature of 30-45 °C, and surface tension of 30-40 mN / m (72 mN / m for pure water). This invention achieves this by adjusting the combination of soft and hard monomers between the shell and core layers of the emulsion, making the shell layer harder than the core layer, thus maximizing the film-forming temperature with less use of hard monomers. Furthermore, by adjusting the process and selecting the emulsion system, the surface tension of the emulsion can be further reduced by utilizing the rational arrangement of carboxyl, amide, and phosphate groups. When no emulsifier containing phosphate groups is added, as shown in Example 2, the surface tension increases, and the viscosity also increases, affecting the leveling effect and stain resistance of the emulsion. As in Example 6, where no organosilicon was added, the film-forming temperature decreased slightly, but the surface tension remained good.

[0095] Table 7. Test results of the emulsion prepared in Test Example 1

[0096]

[0097] 3.2 Test results and analysis of the prepared varnish

[0098] The test results of the prepared varnish and commercially available varnish are shown in Table 8. Table 8 shows that the varnishes prepared in Examples 1-6, compared with commercially available samples, exhibit superior water resistance, whitening resistance, and stain resistance. For Example 2, the emulsion system did not introduce phosphate ester groups, resulting in a decrease in stain resistance. Furthermore, Example 6, lacking the addition of organosilicon, showed a decrease in stain resistance, water resistance, and water-whitening resistance. In addition, the varnish prepared by this invention is highly versatile; its application to stone-like paint substrates using either roller coating or spray coating methods does not significantly affect its gloss.

[0099] Table 8. Test results of varnish

[0100]

[0101] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention, but such modifications or substitutions are all within the scope of protection of the present invention.

Claims

1. A high light purity acrylic emulsion, characterized in that: the emulsifier comprises isooctanol polyoxyethylene ether phosphate; the preparation method of the high light purity emulsion comprises the following steps: S1. respectively preparing a core layer pre-emulsion and a shell layer pre-emulsion, wherein, according to mass fraction, the core layer pre-emulsion comprises 3-10 parts of the acrylic hard monomer, 3-7 parts of the acrylic soft monomer, 0-0.5 parts of the crosslinking monomer, 0.1-1 part of the carboxyl monomer, 0.1-1 part of the organic silicon monomer, 0.5-1 part of the emulsifier, and 0.1-0.3 part of the initiator, and the shell layer pre-emulsion comprises 12-24 parts of the acrylic hard monomer, 2-4 parts of the acrylic soft monomer, 0.8-1.5 parts of the organic silicon monomer, 0.9-1.5 parts of the emulsifier, and 0.1-0.8 part of the initiator; S2. according to mass fraction, 0.5-1 part of the emulsifier is added into 25-35 parts of water to obtain a first reaction liquid, the first reaction liquid is heated to 80-85℃, then 0.1-0.3 part of the initiator is added, and then the core layer pre-emulsion is added dropwise into the reaction system to obtain a second reaction liquid; S3. the shell layer pre-emulsion is added dropwise into the second reaction liquid, during which, according to mass fraction, 1-3 parts of the crosslinking monomer and 0.5-2 parts of the carboxyl monomer are added into the reaction system; S4. after the completion of S3, other additives are added into the reaction system to prepare the high light purity acrylic emulsion; in S3, the dropwise adding time of the shell layer pre-emulsion is divided into a first period and a second period, and the lengths of the first period and the second period are equal; S3 comprises the following operations: a. in the first period, a part of the shell layer pre-emulsion is added dropwise into the second reaction liquid; b. after the end of the first period, the dropwise adding of the shell layer pre-emulsion is paused, the crosslinking monomer and the carboxyl monomer are added into the reaction system, and they are fully dispersed in the reaction system; c. in the second period, the remaining shell layer pre-emulsion is added dropwise into the reaction system; according to mass ratio: in the core layer pre-emulsion, the hard monomer I: the hard monomer II = 2-6: 1-4; in the shell layer pre-emulsion, the hard monomer I: the hard monomer II = 9-18: 3-6; the crosslinking monomer comprises at least one of acrylamide, methacrylamide, glycidyl methacrylate, and acetoacetoxy methyl methacrylate; the emulsifier further comprises at least one of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium dodecyl diphenyl ether disulfonate, fatty alcohol polyoxyethylene ether, alkyl polyoxyethylene ether, 3-allyloxy-2-hydroxy-1-propane sulfonic acid sodium salt, 2-acrylamido-2-methyl propane sulfonic acid sodium, AIDIC SR-10, and AIDIC SR-20; in S4: the additives added into the reaction system comprise a pH regulator and a film forming aid; the addition amount of the pH regulator satisfies that the pH value of the high light purity acrylic emulsion is 6.5-8.

5. The raw materials for preparing the high light-purity acrylic emulsion include acrylic ester monomers, crosslinking monomers, carboxyl monomers, silicone monomers, emulsifiers and initiators, the acrylic ester monomers include acrylic ester hard monomers and acrylic ester soft monomers, the T g value of the acrylic ester soft monomers is -80℃~ -60℃; The acrylate-based hard monomer includes hard monomer I and hard monomer II, the T g value of the hard monomer I is 95℃~105℃, the T g value of the hard monomer II is 10℃~30℃; the hard monomer II includes butyl methacrylate; ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2. The high light purity acrylic emulsion according to claim 1, wherein ​ ​ ​ 3. The high light purity acrylic emulsion according to claim 1, wherein: ​ 4. The high light purity acrylic emulsion according to claim 1, wherein: ​ 5. The high light purity acrylic emulsion of claim 1, wherein ​ ​ ​ The film forming aid includes at least one of alcohol ester twelve, propylene glycol phenyl ether, propylene glycol butyl ether, and Dow COASOL, and the adding amount of the film forming aid satisfies that the minimum film forming temperature of the high light pure acrylic emulsion is 30-45℃. 6.The high light pure acrylic emulsion according to any one of claims 1-5, characterized in that: In the S2, the dropping time of the core layer pre-emulsion into the reaction system is 0.5-1 hours, and after the dropping is completed, the temperature is kept for 0.3-1 hours to obtain the second reaction liquid. In the S3, the dropping time of the shell layer pre-emulsion into the second reaction liquid is 3.5-4.5 hours, and after the dropping is completed, the temperature is kept for 0.5-1.5 hours.

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