A matting agent for water-based paints

Abstract

This invention discloses a matting agent for water-based paints, the preparation method of which includes the following: (1) Preparation of nano-silica: Add a preset amount of water to water glass and stir at a constant temperature until completely dissolved. While heating and stirring, add saturated ammonium chloride solution and polymer to the water glass solution and react. Then, age, separate solid and liquid, and dry the filter residue to obtain silica. Grind the silica to obtain nano-silica; (2) Preparation of matting agent: Heat and stir the nano-silica, dispersant, and adhesion promoter to obtain a matting agent. This invention prepares a matting agent for water-based paints by preparing silica from water glass, saturated ammonium chloride, and polymer. Then, the silica is ground to obtain nano-silica. Adhesion additives and dispersants are added to prevent silica from settling. The rough surface of the silica absorbs light from multiple angles or diffusely reflects it to achieve a matting effect.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a matting agent for water-based paints. Background Technology

[0002] Matting agents disperse suspended particles of a certain size in the coating. During film formation, after the moisture in the coating evaporates, the suspended particles are evenly distributed on the surface of the paint film, thereby increasing the diffuse reflection of light on the paint film and reducing the specular reflectivity of the paint film surface, achieving a semi-matte or matte effect.

[0003] Currently, there are various traditional matting agents on the market. However, with the increasing prominence of environmental issues, traditional solvent-based coatings contain a variety of organic components, which produce harmful gases during production and use, which are detrimental to human health and the environment. Therefore, traditional solvent-based coatings are gradually being replaced by environmentally friendly water-based coatings. Water-based coatings, due to their characteristics such as low oil content, low viscosity, weak buoyancy, and strong fluidity, are not compatible with the large particle size, heavy weight, and high oil absorption of traditional matting agents, resulting in poor matting effect of traditional matting agents in water-based coatings.

[0004] CN109957280A discloses a method for preparing silicone matting agent for paint. The method mainly uses acid soaking, water washing, ammonia soaking, drying, high temperature activation and grinding to obtain silicone particles with a particle size of 1500-3000 mesh. This method can reduce the particle size and weight of silicone. However, the method is relatively cumbersome and cannot improve the adhesion of silicone in water-based paints or make it uniformly distributed.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a matting agent for water-based paints, which aims to improve the suspension and adhesion of the matting agent in water-based paints, while improving its dispersibility so that the matting material is evenly distributed during painting.

[0007] To achieve the above objectives, this application first provides a matting agent for water-based paints, employing the following technical solution:

[0008] A matting agent for water-based paints, characterized in that its preparation method includes the following:

[0009] (1) Preparation of nano-silica: Add a preset amount of water to water glass and stir at a constant temperature until completely dissolved. While heating and stirring, add saturated ammonium chloride solution and polymer to the water glass solution and react. Then, age, separate solid and liquid, and dry the filter residue to obtain silica. Grind the silica to obtain nano-silica.

[0010] (2) Preparation of matting agent: The nano-silica, dispersant and adhesion promoter are heated and stirred to obtain the matting agent.

[0011] According to the above technical solution, the present invention converts the saturated ammonium chloride solution into an unsaturated ammonium chloride solution by adding a saturated ammonium chloride solution to the water glass solution. NH4Cl + H2O = NH4OH + HCl, then NaSiO (water glass) + 2HCl = 2NaCl + H2SiO. The consumption of HCl by NaSiO will further promote the hydrolysis of NH4Cl to form a closed loop. This method solves the problem of acidic waste liquid caused by the traditional acid soaking method.

[0012] Preferably, in the above technical solution, the ratio of water glass to water in the step of preparing nano-silica is 1:3-5.

[0013] Preferably, in the above technical solution, in the step of preparing nano-silica, the temperature of water added to the water glass and stirred at a constant temperature is 35-50℃. After the polymer is added and fully dissolved, a saturated ammonium chloride solution is added and stirred evenly to obtain a mixed solution. Then, the solution is aged, separated from the solid liquid, and the filter residue is dried to obtain silica.

[0014] Preferably, in the above technical solution, in the step of preparing nano-silica, the polymer includes one or more of poly(N-isopropylacrylamide), polyvinyl alcohol, and methyl methacrylate.

[0015] Preferably, in the above technical solution, the aging time in the step of preparing silica from water glass is 7-8 hours.

[0016] Preferably, in the above technical solution, in the step of grinding silica to obtain nano silica, silica is placed in a grinding mill, and a polymer solution is added while grinding. After drying, nano silica is obtained, and the particle size range of the nano silica is 100-200 nm.

[0017] Preferably, in the above technical solution, the specific steps for preparing the matting agent are as follows: under a temperature of 67-78℃, nano-silica is added to an adhesion promoter solution and stirred for 20-30 minutes, and then a dispersant is added to obtain the matting agent.

[0018] Preferably, in the above technical solution, in the step of preparing the matting agent, the nano-silica is 65-77% by mass fraction, the dispersant is 18-32%, and the adhesion promoter is 5-13%.

[0019] Preferably, in the above technical solution, the dispersant includes one or more of cobalt citrate, sodium polyacrylate, sodium silicate, sodium orthophosphate, and sodium pyrophosphate.

[0020] Preferably, in the above technical solution, the adhesion promoter is one or more of erythritol, pentapentine, and glycerol.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The method of this invention for preparing silica is simple, and the silica obtained can meet the requirements of water-based paints for matting agents when used as a matting material. The specific principle is as follows: First, a saturated ammonium chloride solution is added to a water glass solution to form an unsaturated ammonium chloride solution. The ammonium chloride in the unsaturated ammonium chloride solution is easily hydrolyzed to generate NH4·H2O and HCl. Silica is obtained by replacing the silicate ions in the water glass with NaSiO (water glass) + 2HCl = 2NaCl + H2SiO. At a temperature of 35-50℃, due to poly(N-isopropylacrylamide) Intermolecular forces, with the poly(N-isopropylacrylamide) chains in an extended state, can generate van der Waals forces with the silica dimer Si-O in silicic acid, preventing the silica dimer Si-O from combining with silica ions to form silica polymers, thus limiting the increase in silica gel particle size. Secondly, polyvinyl alcohol and methyl methacrylate promote the formation of pores in silica gel particles, improving the porosity of silica. Finally, polyvinyl alcohol and methyl methacrylate form a polymeric protective layer on the surface of nano-silica through hydrogen bonding and electrostatic attraction, reducing the oil absorption of nano-silica.

[0023] (2) In the process of preparing the matting agent by the method of the present invention, firstly, an adhesion promoter is added to the nano-carbon black. Erythritol, pentapentine, and glycerol are uniformly attached to the surface of the nano-carbon black polymer protective layer, which can increase the viscosity of the nano-carbon black and reduce the fluidity of the nano-carbon black in water-based paint. Secondly, a dispersant is added to prevent the nano-carbon black with sodium polyacrylate attached to the surface from sticking together and agglomerating into clumps, which would reduce the matting effect. Detailed Implementation

[0024] The specific embodiments of the present invention will be described in detail below with reference to specific examples, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0025] Example 1

[0026] A matting agent for water-based paints, the preparation method of which includes the following:

[0027] (1) Preparation of nano-silica: Under constant temperature conditions of 35-50℃, add 3-5 parts of water to 1 part of water glass and stir until completely dissolved. Add a polymer to the molten water glass solution and let the polymer dissolve completely. Then add a saturated ammonium chloride solution and stir evenly to obtain a mixed solution. Let the mixed solution stand for 7-8 hours. Use a filter device to separate the solid and liquid after aging. Take the filter residue and remove the filtrate. Dry the filter residue using a low temperature drying method. After drying, silica is obtained. Put the silica into a grinder and add a polymer solution while grinding. After drying, nano-silica is obtained. The particle size range of nano-silica is 100-200nm.

[0028] (2) Preparation of matting agent: At a temperature of 67-78℃, 65-77% nano-silica is added to a 5-13% adhesion promoter solution and stirred for 20-30 minutes. Then, 18-32% dispersant is added to obtain the matting agent.

[0029] Example 2

[0030] A matting agent for water-based paints, the preparation method of which includes the following:

[0031] (1) Preparation of nano-silica: Under constant temperature of 50℃, 5 parts of water are added to 1 part of water glass and stirred until completely dissolved. A mixed polymer of polyvinyl alcohol and poly(N-isopropylacrylamide) is added to the molten water glass solution. After the mixed polymer is fully dissolved, a saturated ammonium chloride solution is added and stirred evenly to obtain a mixed solution. The mixed solution is allowed to stand for 8 hours. The aged material is separated into solid and liquid by a filtration device. The filter residue is removed and the filtrate is removed. The filter residue is dried by low temperature drying to obtain silica. The silica is placed in a grinder and the mixed solution of polyvinyl alcohol and poly(N-isopropylacrylamide) is added while grinding. After drying, nano-silica is obtained, wherein the particle size range of nano-silica is 200nm.

[0032] (2) Preparation of matting agent: At a temperature of 74°C, 73% nano-silica is added to a 5-13% adhesion promoter solution and stirred for 20 minutes. Then, a 25% dispersant solution is added to obtain the matting agent. The adhesion promoter is made of erythritol, pentapentine, and glycerol. The dispersant is made of cobalt citrate, sodium silicate, sodium pyrophosphate, sodium polyacrylate, and sodium orthophosphate.

[0033] Example 3

[0034] A matting agent for water-based paints, the preparation method of which includes the following:

[0035] (1) Preparation of nano-silica: Under constant temperature of 35℃, 3 parts of water are added to 1 part of water glass and stirred until completely dissolved. A mixed polymer of poly(N-isopropylacrylamide) and methyl methacrylate is added to the molten water glass solution. After the polymer is fully dissolved, a saturated ammonium chloride solution is added and stirred evenly to obtain a mixed solution. The mixed solution is allowed to stand for 7 hours. The aged material is separated into solid and liquid by a filtration device. The filter residue is removed and the filtrate is removed. The filter residue is dried by low temperature drying to obtain silica. Silica is placed in a grinder and the mixed solution of poly(N-isopropylacrylamide) and methyl methacrylate is added while grinding. After drying, nano-silica is obtained, wherein the particle size range of nano-silica is 100nm.

[0036] (2) Preparation of matting agent: At a temperature of 67°C, 65% nano-silica was added to a 13% adhesion promoter solution and stirred for 30 minutes. Then, a 32% dispersant solution was added to obtain the matting agent. The adhesion promoter was made of erythritol, pentapentol, and glycerol. The dispersant was made of cobalt citrate, sodium silicate, sodium pyrophosphate, sodium polyacrylate, and sodium orthophosphate.

[0037] Example 4

[0038] A matting agent for water-based paints, the preparation method of which includes the following:

[0039] (1) Preparation of nano-silica: Under constant temperature of 40℃, 4 parts of water are added to 1 part of water glass and stirred until completely dissolved. A mixed polymer of polyvinyl alcohol, poly(N-isopropylacrylamide) and methyl methacrylate is added to the molten water glass solution. After the polymer is fully dissolved, a saturated ammonium chloride solution is added and stirred evenly to obtain a mixed solution. The mixed solution is allowed to stand for 7.5 hours. The aged material is separated into solid and liquid by a filtration device. The filter residue is removed and the filtrate is removed. The filter residue is dried by low temperature drying to obtain silica. The silica is placed in a grinder and the mixed solution of polyvinyl alcohol, poly(N-isopropylacrylamide) and methyl methacrylate is added while grinding. After drying, nano-silica is obtained, wherein the particle size range of nano-silica is 150 nm.

[0040] (2) Preparation of matting agent: At a temperature of 73°C, 70% nano-silica is added to a 5% adhesion promoter solution and stirred for 25 minutes. Then, a 25% dispersant solution is added to obtain the matting agent. The adhesion promoter is made of erythritol, pentapentol and glycerol. The dispersant is made of cobalt citrate, sodium silicate, sodium pyrophosphate, sodium polyacrylate and sodium orthophosphate.

[0041] Example 5

[0042] A matting agent for water-based paints, the preparation method of which includes the following:

[0043] (1) Preparation of nano-silica: Under constant temperature of 50℃, 5 parts of water are added to 1 part of water glass and stirred until completely dissolved. A mixed polymer of polyvinyl alcohol, poly(N-isopropylacrylamide) and methyl methacrylate is added to the molten water glass solution. After the polymer is fully dissolved, a saturated ammonium chloride solution is added and stirred evenly to obtain a mixed solution. The mixed solution is allowed to stand for 8 hours. The aged material is separated into solid and liquid by a filtration device. The filter residue is removed and the filtrate is removed. The filter residue is dried by low temperature drying to obtain silica. Silica is placed in a grinder and the mixed solution of polyvinyl alcohol, poly(N-isopropylacrylamide) and methyl methacrylate is added while grinding. After drying, nano-silica is obtained, wherein the particle size range of nano-silica is 200nm.

[0044] (2) Preparation of matting agent: At a temperature of 78°C, 77% nano-silica is added to 5% adhesion promoter and stirred for 20 minutes, and then 18% dispersant is added to obtain matting agent. The adhesion promoter is made of erythritol, pentapentol and glycerol, and the dispersant is made of cobalt citrate, sodium silicate, sodium pyrophosphate, sodium polyacrylate and sodium orthophosphate.

[0045] Comparative Example 1

[0046] The method is basically the same as in Example 5, except that the preparation method of the silica is different. A matting agent for water-based paints is prepared by the following method:

[0047] (1) Preparation of nano-silica: Under constant temperature of 50℃, add 2 parts of water to 1 part of water glass and stir until completely dissolved. Add 6 mol / L hydrochloric acid solution to the molten water glass solution and stir evenly to obtain a mixed solution. Let the mixed solution stand for 8 hours. Use a filter device to separate the solid and liquid after aging. Take the filter residue and remove the filtrate. Dry the filter residue using a low temperature drying method. After drying, silica is obtained. Put the silica into a grinder for grinding to obtain nano-silica.

[0048] (2) Preparation of matting agent: At a temperature of 78°C, 77% nano-silica is added to 5% adhesion promoter and stirred for 20 minutes, and then 18% dispersant is added to obtain matting agent. The adhesion promoter is made of erythritol, pentapentol and glycerol, and the dispersant is made of cobalt citrate, sodium silicate, sodium pyrophosphate, sodium polyacrylate and sodium orthophosphate.

[0049] Comparative Example 2

[0050] The method is basically the same as in Example 5, except that the preparation method of the silica is different. A matting agent for water-based paints is prepared by the following method:

[0051] (1) Preparation of nano-silica: Under constant temperature of 50℃, 6 parts of water are added to 1 part of water glass and stirred until completely dissolved. Saturated ammonium chloride solution is added to the molten water glass solution and stirred evenly to obtain a mixed solution. The mixed solution is allowed to stand and age for 8 hours. The aged material is separated into solid and liquid by a filtration device. The filter residue is removed and the filtrate is removed. The filter residue is dried by low temperature drying to obtain silica. The silica is then ground in a grinder to obtain nano-silica. The particle size range of nano-silica is 200nm.

[0052] (2) Preparation of matting agent: At a temperature of 78°C, 77% nano-silica is added to 5% adhesion promoter and stirred for 20 minutes, and then 18% dispersant is added to obtain matting agent. The adhesion promoter is made of erythritol, pentapentol and glycerol, and the dispersant is made of cobalt citrate, sodium silicate, sodium pyrophosphate, sodium polyacrylate and sodium orthophosphate.

[0053] Comparative Example 3

[0054] The method is basically the same as in Example 5, except that the preparation method of the silica is different. A matting agent for water-based paints is prepared by the following method:

[0055] (1) Preparation of silica: Under constant temperature of 50℃, 5 parts of water are added to 1 part of water glass and stirred until completely dissolved. A mixed polymer of polyvinyl alcohol, poly(N-isopropylacrylamide) and methyl methacrylate is added to the molten water glass solution. After the polymer is fully dissolved, a saturated ammonium chloride solution is added and stirred evenly to obtain a mixed solution. The mixed solution is allowed to stand for 8 hours. The aged material is separated into solid and liquid by a filtration device. The filter residue is removed and the filtrate is removed. The filter residue is dried by low temperature drying to obtain silica.

[0056] (2) Preparation of matting agent: At a temperature of 78°C, 77% nano-silica is added to 5% adhesion promoter and stirred for 20 minutes, and then 18% dispersant is added to obtain matting agent. The adhesion promoter is made of erythritol, pentapentol and glycerol, and the dispersant is made of cobalt citrate, sodium silicate, sodium pyrophosphate, sodium polyacrylate and sodium orthophosphate.

[0057] Comparative Example 4

[0058] The basic components are the same as in Embodiment 5, the difference being that the preparation method of the matting agent is different. A matting agent for water-based paints is prepared by the following method:

[0059] (1) Preparation of nano-silica: Under constant temperature of 50℃, 5 parts of water are added to 1 part of water glass and stirred until completely dissolved. A mixed polymer of polyvinyl alcohol, poly(N-isopropylacrylamide) and methyl methacrylate is added to the molten water glass solution. After the polymer is fully dissolved, a saturated ammonium chloride solution is added and stirred evenly to obtain a mixed solution. The mixed solution is allowed to stand for 8 hours. The aged material is separated into solid and liquid by a filtration device. The filter residue is removed and the filtrate is removed. The filter residue is dried by low temperature drying to obtain silica. Silica is placed in a grinder and the mixed solution of polyvinyl alcohol, poly(N-isopropylacrylamide) and methyl methacrylate is added while grinding. After drying, nano-silica is obtained, wherein the particle size range of nano-silica is 200nm.

[0060] (2) Preparation of matting agent: At a temperature of 78°C, 77% nano-silica is added to 5% adhesion promoter and stirred for 20 minutes. Then, 18% dispersant is added to obtain the matting agent. The adhesion promoter is made of glycerol and the dispersant is made of cobalt citrate, sodium silicate, sodium pyrophosphate, sodium polyacrylate, and sodium orthophosphate.

[0061] Comparative Example 5

[0062] The basic components are the same as in Embodiment 5, the difference being that the preparation method of the matting agent is different. A matting agent for water-based paints is prepared by the following method:

[0063] (1) Preparation of nano-silica: Under constant temperature of 50℃, 5 parts of water are added to 1 part of water glass and stirred until completely dissolved. A mixed polymer of polyvinyl alcohol, poly(N-isopropylacrylamide) and methyl methacrylate is added to the molten water glass solution. After the polymer is fully dissolved, a saturated ammonium chloride solution is added and stirred evenly to obtain a mixed solution. The mixed solution is allowed to stand for 8 hours. The aged material is separated into solid and liquid by a filtration device. The filter residue is removed and the filtrate is removed. The filter residue is dried by low temperature drying to obtain silica. Silica is placed in a grinder and the mixed solution of polyvinyl alcohol, poly(N-isopropylacrylamide) and methyl methacrylate is added while grinding. After drying, nano-silica is obtained, wherein the particle size range of nano-silica is 200nm.

[0064] (2) Preparation of matting agent: At a temperature of 78°C, 77% nano-silica is added to 5% adhesion promoter and stirred for 20 minutes, and then 18% dispersant is added to obtain matting agent. The adhesion promoter is made of erythritol, pentapentol and glycerol, and the dispersant is made of sodium silicate, sodium pyrophosphate and sodium polyacrylate.

[0065] Comparative Example 6

[0066] The method is basically the same as in Example 5, except that the preparation method of the matting agent is different. A matting agent for water-based paints is prepared by the following method:

[0067] (1) Preparation of nano-silica: Under constant temperature of 50℃, 5 parts of water are added to 1 part of water glass and stirred until completely dissolved. A mixed polymer of methyl methacrylate is added to the molten water glass solution. After the polymer is fully dissolved, a saturated ammonium chloride solution is added and stirred evenly to obtain a mixed solution. The mixed solution is allowed to stand for 8 hours. The aged material is separated into solid and liquid by a filtration device. The filter residue is removed and the filtrate is removed. The filter residue is dried by low temperature drying to obtain silica. The silica is placed in a grinder and a mixed solution of polyvinyl alcohol, poly(N-isopropylacrylamide) and methyl methacrylate is added while grinding. After drying, nano-silica is obtained, wherein the particle size range of nano-silica is 200nm.

[0068] (2) Preparation of matting agent: The obtained nano-silica is used directly as a matting agent.

[0069] Using the above-described Example 5 and Comparative Examples 1-3, silica was prepared to obtain Products 1, 2, 3 and 4. The quality of the silica products was tested according to GB10517 requirements, and the test results are shown in Table 1.

[0070] Table 1 Product Quality of Product 1, Product 2, Product 3 and Product 4

[0071]

[0072] The main performance ranges of the matting agents obtained using Examples 1-5 of the present invention are shown in Table 2 below. The detection methods for the test items are as follows: Particle size determination involves diluting the obtained nano-silica sample to approximately 0.1 wt%, sonicating it for 0.5 hours until the sample is uniformly dispersed, and then performing dynamic light scattering measurement in the range of 0.4-10000 nm using a Malvern nanolaser particle size analyzer. Viscosity was measured according to GB12007.2.

[0073] The adhesion test method involves uniformly applying a matting agent to a coating thickness greater than 50 μm, using a scribing tool to cut out a cross-shaped grid pattern on the coated area, then applying strong adhesive tape to the grid pattern and peeling it off. The adhesion ISO rating is divided into 0, 1, 2, 3, and 4, and the judgment criteria are as follows:

[0074] iOS Level 0: The edges of the cut are completely smooth, and there is no separation of the grid edges;

[0075] iOS Level 1: Small pieces peel off at the intersection of the cuts, and the actual damage within the gridded area does not exceed 5%;

[0076] iOS Level 2: There is peeling at the edges or intersections of the cut, with the peeling area within the gridded area being less than 15% (5% ≤ 5%).

[0077] iOS Level 3: There is partial or large-scale peeling along the cut edge, and some grids are peeled off in whole, with 15% ≤ peeling area within the grid area < 35%;

[0078] iOS Level 4: Large areas of the cut edge are peeling off, or some squares are partially peeling off, or some squares are completely peeling off, with 35% ≤ peeling area within the gridded area < 65%.

[0079] Table 2 Performance of the water-based paint matting agent obtained in this invention

[0080] Testing items Test results Testing items Test results <![CDATA[Specific surface area (m 2 / g)]]> 350-380 Dispersion good Average particle size (μm) 150 Viscosity (CPS) 70 Oil absorption value (ml / 100g) 100-230 Adhesion (IOS rating) 1

[0081] The water-based paint matting agent prepared in Example 5 and the water-based paint matting agents prepared in Comparative Examples 1-5 were mixed with Nippon Paint water-based paint and applied to the wall surface. The matting effect of the mixture and Nippon Paint water-based paint at 20°, 60°, and 85° was observed. The matting effect was determined according to the national standard GB / T9754-2007. The water-based paint mixed with the matting agent was applied to a vertical paint film applicator in the same manner and at the same content. The gloss of the film at 20°, 60°, and 85° was measured, and the reflectivity was tested using a light trapping machine. The mixture was stirred rapidly at 2000 rpm for 5 minutes to simulate the paint drying time. After standing for 40 minutes, the sedimentation of silica particles in each matting agent was detected. The results are shown in Table 3.

[0082] Table 3. Performance Test Results of Matting Agent

[0083]

[0084]

[0085] The results are shown in Table 3. The matting agent obtained using the method of the present invention in Example 5, compared with Comparative Example 1, has a better matting effect under specular light at different angles, with less sedimentation and good dispersion performance. This indicates that the use of saturated ammonium chloride and polymer to prepare silica can reduce the binding of silica dimers and silica ions, thus reducing the particle size of silica. The polymer combined with NH4·H2O formed by the hydrolysis of ammonium chloride has a weak electrolyte effect, which can increase the gap between silica dimers, thereby increasing the internal porosity of silica. The high porosity makes the surface of silica rough, which absorbs light from different angles and reduces diffuse reflection. The addition of polymer solution during the grinding of nano silica forms a polymer film structure on the surface of nano silica, reducing the absorption of water from Nippon Paint's water-based paint. The addition of dispersants and adhesion promoters further disperses silica evenly and reduces sedimentation, preventing nano silica from sliding down the wall during painting. Therefore, the matting effect is better. The matting agent obtained using the method of the present invention in Example 5, compared with Comparative Example 3, has smaller particle size of milled silica. Due to its small particle size and light weight, it exhibits better suspension properties in water-based paints. Because of its small particle size and light weight, the silica is less affected by gravity during actual painting, and the nano-silica sinks and settles less along the wall. Compared with Comparative Example 4, the matting agent obtained using the method of the present invention in Example 5 shows better settling and matting effect, indicating that using erythritol, pentapentanol, and glycerol as adhesion promoters can promote better adhesion between silica and water-based paint and the wall surface, reduce relative sliding of silica along the wall surface, reduce silica accumulation, and thus improve matting performance. Compared with Comparative Example 5, the matting agent obtained using the method of the present invention in Example 5 shows that the composition of the dispersant has a significant impact on the matting effect of the matting agent. Compared with Comparative Example 6, the matting agent obtained using the method of the present invention in Example 5 shows that the addition of a dispersant helps to ensure uniform distribution of silica and prevent sedimentation, while the addition of an adhesion promoter increases the adhesion of silica to water-based paints and walls, thereby preventing silica sedimentation and aggregation in the matting agent, which would otherwise result in a low matting effect. Through the above comparison, it is clear that the matting agent prepared using the method of the present invention has the best matting effect.

[0086] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A matting agent for water-based paints, characterized in that, Its preparation methods include the following: (1) Preparation of nano-silica: Add a preset amount of water to water glass and stir at a constant temperature until completely dissolved. While stirring, add saturated ammonium chloride solution and polymer to the water glass solution and react. Then, age, separate solid and liquid, and dry the filter residue to obtain silica. Put the silica into a grinder and grind it while adding polymer solution. After drying, obtain nano-silica. The particle size range of the nano-silica is 100-200nm. The polymer is composed of polyvinyl alcohol, poly(N-isopropylacrylamide) and methyl methacrylate. (2) Preparation of matting agent: A matting agent is obtained by heating and stirring 65-77% nano-silica, 18-32% dispersant, and 5-13% adhesion promoter. The dispersant is composed of cobalt citrate, sodium polyacrylate, sodium silicate, sodium orthophosphate, and sodium pyrophosphate. The adhesion promoter is composed of erythritol, pentapentol, and glycerol.

2. The matting agent for water-based paints according to claim 1, characterized in that, In the step of preparing nano-silica, the ratio of water glass to water is 1:3-5.

3. The matting agent for water-based paints according to claim 1, characterized in that, The water glass is added and stirred at a constant temperature of 35-50℃. The polymer is then added and fully dissolved. A saturated ammonium chloride solution is then added and stirred until homogeneous to obtain a mixed solution. The mixed solution is then aged, separated into solid and liquid components, and the filter residue is dried to obtain silica.

4. The matting agent for water-based paints according to claim 3, characterized in that, In the step of preparing silica from water glass, the aging time is 7-8 hours.

5. The matting agent for water-based paints according to claim 1, characterized in that, The specific steps for preparing the matting agent are as follows: at a temperature of 67-78℃, an adhesion promoter solution is added to nano-silica and stirred for 20-30 minutes, and then a dispersant is added to obtain the matting agent.

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