High hiding yellow acrylic topcoat and method of making same

Abstract

The application discloses a high-hiding yellow acrylic finish and a preparation method thereof, and belongs to the technical field of paints. The high-hiding yellow acrylic finish provided by the application can effectively improve the hiding power, color development and dispersion stability of the finish by selecting components with appropriate mass percentages and the mutual cooperation between the components, and has excellent early water resistance. Meanwhile, the preparation method of the finish is simple to operate, does not require special equipment, and is beneficial to actual production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coating, and particularly relates to a high-hiding yellow acrylic topcoat and a preparation method thereof. BACKGROUND

[0002] The hiding power of a coating refers to the ability of a color paint to cover a substrate or a base color, which is related to the scattering and absorption of light by pigments and is an important property of the color paint. Among common color paints, yellow, orange and red paints exhibit poor hiding power, especially yellow paint. Compared with traditional organic pigments, lead-chromium pigments have a low oil absorption value, good dispersibility and little influence on the production process of water-based coatings. Some lead-chromium pigments, such as chrome yellow and molybdenum-chromium red, have a high refractive index and are more likely to achieve high hiding power. However, they contain hexavalent chromium, lead and cadmium, which pollute the environment and harm human health, and lead-free pigments are gradually used to replace lead-chromium pigments. At present, the poor hiding power of yellow paint is a technical problem in the coating industry. The addition of a certain amount of titanium white powder can effectively improve the hiding power of yellow paint, but the amount of titanium white powder cannot be too high, otherwise the color will be diluted, especially for deep yellow paint. In addition, increasing the thickness of the paint film, increasing the PVC, using a color topcoat similar to the color of the base paint or intermediate paint is often used to improve the hiding power of yellow paint. However, these methods will bring inconvenience to construction or production, and the cost is also relatively high. SUMMARY

[0003] The present application aims to overcome the shortcomings of the prior art and provide a high-hiding yellow acrylic topcoat with excellent color development, strong hiding power, good dispersion stability and good early water resistance, and a preparation method thereof.

[0004] To achieve the above-mentioned purpose, in the first aspect of the present application, the present application provides a high-hiding yellow acrylic topcoat, which comprises the following components by mass percentage:

[0005] 25-50% polymer resin A, 10-28% polymer resin B, 0.4-1% wet dispersant, 0.1-0.5% defoaming agent, 12-20% pigment composition, 1.5-6% filler, 0.1-0.3% pH adjuster, 2.5-5% film-forming aid, 0.6-2% anti-settling agent, 0.3-0.6% thickening agent, and the balance water;

[0006] The polymer resin A comprises an acrylic copolymer emulsion, and the polymer resin B comprises polystyrene microspheres, and the mass ratio of the polymer resin A to the polymer resin B is (5-8):(2-5);

[0007] The pigment composition comprises modified zinc oxide and inorganic-organic composite yellow pigment;

[0008] The wet dispersant comprises a non-ionic surfactant of a fatty alcohol alkyl ether and a styrene maleic anhydride derivative in a mass ratio of (1-2):(4-8).

[0009] The high-hiding yellow acrylic finish paint provided by the application can effectively improve the hiding power, color development and dispersion stability of the finish paint by selecting appropriate mass percentages of components and the mutual synergy between the components, and has excellent early water resistance.

[0010] Specifically, the polymer resin A and the polymer resin B of specific types and mass percentage ranges are compounded in a specific mass ratio, which can effectively increase the microscopic unevenness of the paint film formed by the finish paint, the increase in the surface roughness of the paint film can reduce the light transmittance of the finish paint; specifically, the polymer resin B selected by the application is polystyrene microspheres, which have a core-shell structure, a relatively high film formation temperature and a relatively large surface roughness, and the grafts on the surface thereof will migrate to the surface of the paint film within a certain range to form a heterogeneous structure on the surface of the paint film, and the polymer resin B can also be well compounded with the polymer resin A, and the film formation of the paint film is good. The pigment composition selected by the application is compounded with modified zinc oxide and inorganic-organic composite yellow pigments, which not only have good thermal stability, weather resistance and chemical resistance on the basis of environmental protection and safety, but also can effectively improve the hiding power of the finish paint; in addition, the type of the wet dispersant selected by the application has excellent synergistic effect, good wetting and dispersing capacity for pigments, improves color floating and blooming, and also improves the stability of the pigments, thereby effectively improving the color development effect of the finish paint, reducing the hiding thickness of the coating, and improving the stability of the finish paint.

[0011] Preferably, the polymer resin A is an acrylic copolymer emulsion.

[0012] More preferably, the acrylic copolymer emulsion has a minimum film formation temperature of 20-40℃.

[0013] Illustratively, the acrylic copolymer emulsion can be PRO1552, MT-3628 of Guangdong Lande Fort New Material Co., Ltd., and 0624, etc.

[0014] Illustratively, the mass ratio of the polymer resin A and the polymer resin B can be any point value or any two-point range value between (5-8):(2-5), such as 5:2, 5:3, 5:5, 6:2, 6:3, 6:5, 8:2, 8:3, 8:5, etc.

[0015] Exemplarily, the mass ratio of the non-ionic surfactant of the fatty alcohol alkyl ether and the styrene maleic anhydride derivative can be any point value or any two-point range value between (1-2):(4-8), such as 1:4, 1:6, 1:8, 2:4, 2:6, 2:8, etc.

[0016] Exemplarily, the non-ionic surfactant of the fatty alcohol alkyl ether can be NOVELUTION KG4, NOVELUTION KG5, NOVELUTION K08, etc. of SACHEM (CHINA) CHEMICAL CO., LTD.; and the styrene maleic anhydride derivative can be Gresssol DP1030, Gresssol DP2200, Gresssol DP1190, etc. of Yueyang Kaimen Water-based Additives Co., Ltd., and DISPERBYK 2010 of BYK-Chemie.

[0017] As a preferred embodiment of the topcoat of the present application, the preparation method of the polymer resin B comprises the following steps:

[0018] (1) styrene maleic anhydride copolymer and ammonia water are added to deionized water, heated to 40-60℃, stirred until the system is clear and transparent, then a part of styrene is added, and the temperature is continuously raised to 70-90℃, stirred for 30-60min, then the remaining part of the initiator aqueous solution is added, and the system is kept for 30-60min after the system turns blue, to obtain a mixed solution;

[0019] (2) the remaining part of styrene and divinylbenzene are mixed uniformly to obtain monomer solution 1, and a part of the monomer solution 1 is taken and mixed uniformly in vinyl triisopropoxy siloxane to obtain monomer solution 2;

[0020] (3) monomer solution 1 and another part of the initiator aqueous solution are added dropwise to the mixed solution in step (1), monomer solution 2 is added dropwise after the addition of monomer solution 1 is completed, and the reaction is continued for 40-70min after the dropwise addition is completed, then the remaining part of the initiator aqueous solution is added and kept for 60-90min, then the temperature is lowered, and the product is discharged, to obtain polystyrene microspheres.

[0021] The present application researches and finds that the polystyrene microspheres prepared by the preparation method provided by the present application have a core-shell structure, and the surface is grafted with organosiloxane chain segments; on the one hand, the surface roughness of the prepared polystyrene microspheres is large, so as to increase the roughness of the paint film surface, increase the scattering of light, reduce the light transmittance of the paint film, and improve the hiding power of the paint film; on the other hand, the organosiloxane chain segments on the surface of the polystyrene microspheres will migrate to the paint film surface within a certain range, forming a heterogeneous structure on the paint film surface, further increasing the microscopic unevenness of the paint film, and improving the hiding power of the paint film.

[0022] As a preferred embodiment of the topcoat of the present application, the mass percentage of styrene maleic anhydride is 15-30%, the mass percentage of divinylbenzene is 1-4%, the mass percentage of vinyl triisopropoxy siloxane is 0.5-2.5%, and the mass percentage of initiator is 1-2% based on the total mass of the reaction monomers.

[0023] It should be noted that the reaction monomers include styrene, divinylbenzene and vinyl triisopropoxy siloxane.

[0024] As a preferred embodiment of the topcoat of the present application, the mass percentage of initiator in the aqueous initiator solution is 1.5-2.5%, and the initiator is 2,2'-azobis(2-methylpropionamidine) dihydrochloride.

[0025] As a preferred embodiment of the topcoat of the present application, the number average relative molecular mass of the styrene maleic anhydride copolymer is 2500-3500.

[0026] Illustratively, the styrene maleic anhydride copolymer can be SER11 of Yueyang Kaimen Water-based Additives Co., Ltd., and the number average relative molecular mass, weight average relative molecular mass and acid value thereof are 2500-3500, 4500-5500 and 480 mgKOH / g, respectively.

[0027] As a preferred embodiment of the topcoat of the present application, in the step (1), the part of styrene accounts for 15-25% of the total mass of styrene; in the step (3), the other part of the aqueous initiator solution accounts for 60-70% of the total mass of the aqueous initiator solution, and the remaining part of the aqueous initiator solution accounts for 10-20% of the total mass of the aqueous initiator solution.

[0028] In the preparation method of the polymer resin B, the ammonia water is added to adjust the pH value of the aqueous solution to 7.5-9, so as to neutralize the styrene maleic anhydride copolymer and help the styrene maleic anhydride copolymer to dissolve in water, thereby obtaining a clear and transparent system.

[0029] As a preferred embodiment of the topcoat of the present application, the preparation method of the modified zinc oxide comprises the following steps:

[0030] After the nano zinc oxide is added to the modified solution and ultrasonically dispersed, the reaction is heated, and after the reaction is completed, the modified zinc oxide is obtained by filtering, washing and drying;

[0031] The preparation method of the modified solution is that 3-glycidyl ether oxypropyl triethoxysilane is added to 95% aqueous ethanol solution, mixed uniformly, and then the pH value is adjusted to 3-4.

[0032] The application researches and finds that the modified zinc oxide prepared by the method has significantly improved stability, can be well compounded with other pigments, improves the floating color of the system, and improves the dispersion stability of the topcoat.

[0033] As a preferred embodiment of the topcoat, the mass percentage of the 3-glycidyloxypropyl triethoxysilane is 0.5-2% based on the mass of the nano zinc oxide.

[0034] As a preferred embodiment of the topcoat, the mass percentage of the 3-glycidyloxypropyl triethoxysilane in the modified solution is 0.5-1%.

[0035] As a preferred embodiment of the topcoat, the ultrasonic dispersion time is 30-60 min.

[0036] As a preferred embodiment of the topcoat, the heating reaction temperature is 40-60℃, and the time is 90-150 min.

[0037] As a preferred embodiment of the topcoat, the drying temperature is 80-100℃.

[0038] Preferably, the pH value is adjusted to 3-4 by adding acetic acid.

[0039] As a preferred embodiment of the topcoat, the pigment composition further comprises at least one of iron oxide yellow, rutile titanium-chromium pigment, and rutile titanium-nickel pigment.

[0040] Preferably, the pigment composition comprises modified zinc oxide, rutile titanium-chromium pigment, iron oxide yellow, and inorganic-organic composite yellow pigment, and the mass ratio of the modified zinc oxide, rutile titanium-chromium pigment, iron oxide yellow, and inorganic-organic composite yellow pigment is 7:5:1:(60-70).

[0041] The application researches and finds that different choices and mass ratios of components in the pigment composition will affect the coloring effect of the topcoat. By selecting the above type of pigment composition, adding a variety of inorganic pigments with high opacity such as modified zinc oxide, rutile titanium-chromium pigment, and iron oxide yellow in the inorganic-organic composite yellow pigment can effectively improve the hiding power of the topcoat, and the amount is relatively low, and the influence on the color tone is small. At the same time, the compounded wet dispersant has a synergistic effect on the color development of the yellow pigment, so that the pigment composition can present obvious yellow after wet dispersion.

[0042] Exemplarily, the rutile titanium chromium pigment is a titanium dioxide modified rutile crystal structure, which can be HEUCODUR YELLOW 9064, HEUCODUR YELLOW 9116, HEUCODUR YELLOW 3R, HEUCODUR YELLOW 253, etc. of Heubach Shanghai Co., Ltd.

[0043] Exemplarily, the iron oxide yellow can be Yellow 311, Yellow 313, Yellow 315, Yellow 810, etc. of Tongling Ruilai Technology Co., Ltd.

[0044] Exemplarily, the inorganic-organic composite yellow pigment is a color titanium pigment composed of an organic pigment and an inorganic titanium yellow pigment, which can be YELLOW T-53-09, YELLOW T-84-03, YELLOW Y-84-01, YELLOW Y-34-70, etc. of Guangzhou Jilang Environmental Protection Technology Co., Ltd.

[0045] As a preferred embodiment of the topcoat of the present application, the defoaming agent comprises a modified silicone defoaming agent containing hydrophobic particles.

[0046] Exemplarily, the defoaming agent can be Coadd DF-9040 of Puwei (Shanghai) New Material Technology Co., Ltd. TM

[0047] As a preferred embodiment of the topcoat of the present application, the filler comprises at least one of wollastonite and aluminum silicate zeolite.

[0048] Exemplarily, the wollastonite can be SC-800 of Guangfu Jiancai (Jiaoling) Refining Co., Ltd., with an average particle size of 3.5 μm and whiteness ≥ 89%.

[0049] Exemplarily, the aluminum silicate zeolite can be ZEOCROS CG180 of Guangzhou Dongbo Chemical Co., Ltd., with an average particle size of 1.2 μm and specific gravity of 2 g / mL.

[0050] As a preferred embodiment of the topcoat of the present application, the pH regulator comprises N,N-dimethylethanolamine.

[0051] As a preferred embodiment of the topcoat of the present application, the film-forming aid comprises at least one of alcohol ester twelve and ethylene glycol butyl ether.

[0052] Preferably, the film-forming aid comprises alcohol ester twelve and ethylene glycol butyl ether in a mass ratio of 1: (0.5-1.5).

[0053] More preferably, the film-forming aid comprises alcohol ester twelve and ethylene glycol butyl ether in a mass ratio of 1:1.​

[0054] The present application has found that when the film-forming aid is further selected to include the above-mentioned substances, especially the above-mentioned substances in the mass ratio, the comprehensive performance of the topcoat obtained is better.

[0055] As a preferred embodiment of the topcoat of the present application, the anti-settling agent includes a water-based polyamide wax.

[0056] Preferably, the anti-settling agent is a pre-prepared water slurry of the water-based polyamide wax, and the mass ratio of the water-based polyamide wax to water in the anti-settling agent is 1: (2-4).

[0057] More preferably, the anti-settling agent is a pre-prepared water slurry of the water-based polyamide wax, and the mass ratio of the water-based polyamide wax to water in the anti-settling agent is 1:3.

[0058] Illustratively, the water-based polyamide wax can be HP-337 of Hangzhou Haidis New Material Co., Ltd.

[0059] As a preferred embodiment of the topcoat of the present application, the thickening agent includes a non-ionic polyurethane thickening agent.

[0060] Illustratively, the thickening agent can be U505.

[0061] In a second aspect of the present application, the present application provides a preparation method of the topcoat, the preparation method comprising the following steps:

[0062] (1) mixing water and a wetting dispersant for first dispersion, then adding part of a defoaming agent for second dispersion, followed by adding a pigment composition and a filler for third dispersion to obtain a slurry, and then sanding the slurry to obtain a refined slurry;

[0063] (2) mixing a polymer resin A and a polymer resin B for fourth dispersion, then adding a pH adjuster for fifth dispersion to obtain a mixture;

[0064] (3) adding the refined slurry in step (1) to the mixture in step (2) for sixth dispersion, then adding an anti-settling agent for seventh dispersion, followed by adding the remaining part of the defoaming agent and a film-forming aid for eighth dispersion, and finally adding a thickening agent in batches to adjust the viscosity and then filtering to obtain the topcoat.

[0065] The preparation method of the topcoat provided by the present application is simple to operate and is conducive to actual production.

[0066] As a preferred embodiment of the preparation method of the present application, the fineness of the refined slurry is ≤30 μm.

[0067] As a preferred embodiment of the preparation method of the present application, the viscosity is 85-90 KU.

[0068] As a preferred embodiment of the preparation method of the present application, the first dispersion speed is 400-800 rpm for 3-10 min; the second dispersion speed is 400-800 rpm for 10-15 min; the third dispersion speed is 800-1500 rpm for 15-30 min; the fourth dispersion speed is 300-800 rpm for 5-8 min; the fifth dispersion speed is 300-800 rpm for 5-8 min; the sixth dispersion speed is 600-1000 rpm for 10-15 min; the seventh dispersion speed is 600-1000 rpm for 10-15 min; and the eighth dispersion speed is 800-1200 rpm for 10-15 min.

[0069] As a preferred embodiment of the preparation method of the present application, the filtration is through a 100-300 mesh filter screen.

[0070] Compared with the prior art, the present application has the following beneficial effects:

[0071] The high-hiding yellow acrylic finish provided by the present application can effectively improve the hiding power, color development and dispersion stability of the finish by selecting suitable mass percentages of components and the mutual synergy between the components, and has excellent early water resistance. Meanwhile, the preparation method of the finish is simple to operate and does not require special equipment, which is conducive to actual production. DETAILED DESCRIPTION

[0072] For the purpose of better illustrating the object, technical scheme and advantages of the present application, the present application will be further described in combination with specific examples.

[0073] The reagents, methods and equipment used in the present application are all conventional reagents, methods and equipment in the art unless otherwise specified; and the components used in the examples and comparative examples are consistent unless otherwise specified.

[0074] Polymer resin A-1: acrylic copolymer emulsion, PRO 1552, BASF New Materials Co., Ltd.

[0075] Polymer resin A-2: acrylic copolymer emulsion, 0624, Wanhua Chemical Group Co., Ltd.

[0076] Polymer resin B: polystyrene microspheres, self-made, the preparation method comprising the following steps:

[0077] (1) In a 250 mL four-necked flask, 10 g of styrene maleic anhydride copolymer SMA (SER11, Yueyang Kaimen Water-based Additives Co., Ltd.), 74 g of deionized water and 3.5 g of ammonia water were sequentially added, and the system was heated to 50°C under stirring until it became transparent. 0.75 g of 2,2'-azobis (isobutylamidine) dihydrochloride V50 and 36.75 g of deionized water were stirred and dissolved in a beaker to obtain an initiator aqueous solution. Then, 5 g of styrene and 20% initiator aqueous solution were added, and the system was heated to 85°C after stirring for 30 min. When the reaction system turned blue, it was kept at 85°C for 30 min.

[0078] (2) 43 g of styrene and 1 g of divinylbenzene were mixed in a beaker to obtain monomer solution 1. One third of the monomer solution 1 was added to 1 g of vinyl triisopropoxy siloxane to obtain monomer solution 2.

[0079] (3) The monomer solution 1 and 65% initiator aqueous solution were simultaneously added dropwise to the flask. After the addition of the monomer solution 1 was completed, the addition of the monomer solution 2 was started. The dropwise addition of the monomer solution and the initiator aqueous solution was completed in about 180 min.

[0080] (4) After the dropwise addition was completed, the reaction was continued for 60 min, then the remaining initiator aqueous solution was added, and the temperature was kept at 85°C for 60 min. The temperature was then lowered to room temperature, and the product was discharged.

[0081] Wetting dispersant 1: a mixture of a fatty alcohol alkyl ether nonionic surfactant (NOVELUTION KG4, SACHEM China Chemical Co., Ltd.) and a styrene maleic anhydride derivative (Gresssol DP1030, Yueyang Kaimen Water-based Additives Co., Ltd.) in a mass ratio of 1:7.

[0082] Wetting dispersant 2: the difference from wetting dispersant 1 is that the mass ratio of NOVELUTION KG4 and Gresssol DP1030 is 1.5:7.

[0083] Wetting dispersant 3: the difference from wetting dispersant 1 is that the mass ratio of NOVELUTION KG4 and Gresssol DP1030 is 2:7.

[0084] Wetting dispersant 4: the difference from wetting dispersant 1 is that the mass ratio of NOVELUTION KG4 and Gresssol DP1030 is 1:4.

[0085] Wetting dispersant 5: the difference from wetting dispersant 1 is that the mass ratio of NOVELUTION KG4 and Gresssol DP1030 is 1:5.5.

[0086] Wetting dispersant 6: the difference from wetting dispersant 1 is that the mass ratio of NOVELUTION KG4 and Gresssol DP1030 is 1:8.

[0087] Wetting dispersant 7: the difference from wetting dispersant 1 is that NOVELUTION K08 is used instead of NOVELUTION KG4, and Gresssol DP1190 is used instead of Gresssol DP1030.

[0088] Wetting dispersant 8: the difference from wetting dispersant 1 is that the mass ratio of NOVELUTION KG4 and Gresssol DP1030 is 1:10.

[0089] Wetting dispersant 9: the difference from wetting dispersant 1 is that the mass ratio of NOVELUTION KG4 and Gresssol DP1030 is 2:3.5.

[0090] Defoaming agent: modified silicone defoaming agent containing hydrophobic particles, Coadd TM DF-9040, Puwei (Shanghai) New Material Technology Co., Ltd.

[0091] Pigment composition 1: a mixture of modified zinc oxide, rutile titanium-chromium pigment (HEUCODUR YELLOW 9064, Heubach Shanghai Co., Ltd.), iron oxide yellow (Yellow 311, Tongling Ruili Technology Co., Ltd.), and inorganic-organic composite yellow pigment (YELLOW T-53-09, Guangzhou Jilang Environmental Protection Technology Co., Ltd.) in a mass ratio of 7:5:1:65;

[0092] wherein the modified zinc oxide is self-made, and the preparation method comprises the following steps:

[0093] 0.5 g of 3-glycidyloxypropyl triethoxysilane is added into 100 g of 95% ethanol, stirred uniformly, then acetic acid is added dropwise until the pH is 3-4, 50 g of nano-zinc oxide is then added, ultrasonic dispersion is performed for 30 min, then reaction is performed at 50°C under mechanical stirring for 120 min, after cooling to room temperature, suction filtration is performed, 95% ethanol is used for washing 5 times, and finally drying is performed in a 100°C oven to obtain the modified zinc oxide.

[0094] Pigment composition 2: the difference from pigment composition 1 is that the rutile titanium-chromium pigment is not added, and a mixture of modified zinc oxide, iron oxide yellow (Yellow 311, Tongling Ruili Technology Co., Ltd.), and inorganic-organic composite yellow pigment (YELLOW T-53-09, Guangzhou Jilang Environmental Protection Technology Co., Ltd.) in a mass ratio of 7.5:1:69.5 is formed;

[0095] Pigment composition 3: the difference from pigment composition 1 is that the modified zinc oxide is replaced by zinc oxide.

[0096] Filler: a mixture of wollastonite (SC-800, Guangfu Jiancai (Jiangling) Fine Chemical Co., Ltd.) and aluminum silicate zeolite (ZEOCRO SCG180, Guangzhou Dongbo Chemical Co., Ltd.) in a mass ratio of 1:1.

[0097] pH regulator: N,N-dimethylethanolamine, commercially available.

[0098] Film-forming aid: a mixture of alcohol ester twelve and ethylene glycol butyl ether in a mass ratio of 1:1, both of which are commercially available.

[0099] Anti-settling agent: a pre-prepared water slurry of water-based polyamide wax (HP-337, Hangzhou Haidis New Material Co., Ltd.), wherein the mass ratio of water-based polyamide wax to water is 1:3.

[0100] Thickening agent: non-ionic polyurethane, U505, Wanhua Chemical Group Co., Ltd.

[0101] Examples 1-13 and Comparative Examples 1-5

[0102] The present application provides a high-hiding yellow acrylic finish, the components (mass percentage) of which are shown in Tables 1-3;

[0103] Table 1

[0104]

[0105]

[0106] Table 2

[0107]

[0108] Table 3

[0109]

[0110]

[0111] The preparation method of the high-hiding yellow acrylic finish provided in Example 1 includes the following steps:

[0112] (1) Add water and wetting dispersant into a dispersion kettle in sequence, disperse at a speed of 600 rpm for 6 min, then add 40% defoaming agent, and disperse for 12 min;

[0113] (2) In the dispersing kettle of step (1), add pigment composition 1 and filler, and then adjust the rotation speed to 1200 rpm, disperse for 22 min, and then sand the slurry until the fineness is less than or equal to 30 μm;

[0114] (3) In another dispersing kettle, add polymer resin A and polymer resin B, disperse at a rotation speed of 600 rpm for 6 min, add pH regulator, and continue to disperse for 6 min;

[0115] (4) In the dispersing kettle of step (3), add the slurry of step (2), disperse at a rotation speed of 800 rpm for 12 min, and then add anti-settling agent, and continue to disperse for 12 min. Then, add 60% defoaming agent and film-forming aid in sequence, disperse at 1000 rpm for 12 min. Finally, add thickening agent in small amounts and multiple times at a rotation speed of 1000 rpm, adjust the viscosity of the paint to 85-90 KU, filter through a 200 mesh screen, collect the filtrate, and obtain high-hiding yellow acrylic topcoat.

[0116] The preparation method of the high-hiding yellow acrylic topcoat provided by Examples 2-13 and Comparative Examples 1-5 is consistent with that of Example 1.

[0117] Effect Example

[0118] The performance of the high-hiding yellow acrylic topcoat prepared by Examples 1-13 and Comparative Examples 1-5 is verified in the effect example, including the following aspects:

[0119] (1) Liquid paint state: After the sample paint is sealed, it is placed in an oven at 50°C for 14 days, and then taken out and cooled to room temperature. The appearance is observed to see if there is a color floating phenomenon. The color floating degree is graded from 1 to 8: 1 indicates almost no color floating; 8 indicates very serious color floating; and 2-7 are graded according to the severity of color floating. Then, the paint is stirred with a spatula, and abnormal conditions are observed.

[0120] (2) Color development test: After the sample paint is stirred uniformly, a 200 μm wire bar applicator is used to apply it on black and white paper, the wet film is dried at room temperature for 24 h, and the color is compared by visual observation. The closer the color is to the main color system (deep yellow according to the national standard), the better the color development. The color development is graded from 1 to 8: 1 indicates very light color; 8 indicates deep color, very close to the main color system; and 2-7 are graded according to the color depth.

[0121] (3) Thickness of the covered layer: Air-assisted spraying is used to spray on black and white paper until the paint film completely covers the black and white paper. Then, the paint film is dried at room temperature for 24 h, and the thickness of the paint film, i.e. the thickness of the covered layer, is measured by an ultrasonic coating thickness gauge.

[0122] (4) Finger Rub Test: After the sample paint is stirred evenly, a 250 μm wire rod applicator is used to spread on black and white paper. Before the paint film is dry to the touch, gently rub the same area with the palm of the hand 20 times, then place the paint film at room temperature for 24 hours, and then visually compare the color difference between the rubbed area and the non-rubbed area. The smaller the color difference, the better the dispersion stability of the pigment. The color difference is graded from 1 to 8: 1 indicates almost no color difference; 8 indicates a very large color difference; and 2-7 are graded according to the size of the color difference.

[0123] (5) Early water resistance: The panels are prepared and tested according to Table 5 of HG / T 5176-2017. The yellow acrylic water-based paint of the present application is used as the topcoat, and the matching primer is JT-205D from Guangzhou Jitai Chemical Co., Ltd.

[0124] The results are shown in Table 4.

[0125] Table 4

[0126]

[0127]

[0128] As can be seen from Table 4, when the technical solution provided by the present application is used, the product obtained has excellent comprehensive effect, which is reflected in that there is almost no color bleeding after storage, the color development is excellent, the thickness of the covered coating is small, and the dispersion stability of the pigment is excellent, and it also has good early water resistance. Specifically, the liquid paint grade of the product obtained is below 4, and there is no abnormality after spatula stirring; the color development test is 5 or more; the thickness of the covered coating is not more than 105 μm, the finger rub test is 3 or less, and the early water resistance is more than 24 hours.

[0129] As can be seen from Examples 1, 3-5 and Comparative Examples 1-2, the mass ratio between the polymer resin A and the polymer resin B in the topcoat and the mass percentage of the addition will affect the comprehensive performance of the product. When the mass percentage of the polymer resin B in Comparative Example 1 is too small, the covering thickness of the paint film is higher than 110 μm, i.e. the hiding power of the paint film is poor; when the mass percentage of the polymer resin B in Comparative Example 2 is too large, the liquid state of the product obtained is poor, and the spatula stirring after storage will cause gelation.

[0130] As can be seen from Example 1, Examples 6-10 and Comparative Examples 3-4, the mass ratio of the wet dispersant also affects the comprehensive performance of the product. When the mass ratio of Gresssol DP1030 in the wet dispersant of Comparative Example 3 is too high, the hiding power of the topcoat obtained is slightly improved, but the early water resistance is poor; when the mass ratio of NOVELUTION KG4 in the wet dispersant of Comparative Example 4 is too high, the hiding power of the topcoat obtained is also improved to some extent, but the early water resistance of the paint film is significantly reduced, and the early water resistance time is less than 24 h;

[0131] As can be seen from Example 1 and Comparative Example 5, the type of pigment composition also affects the comprehensive performance of the product. When the pigment composition used in Comparative Example 5 is not provided by the present application, the liquid paint state of the product obtained is poor, and the paint appears to be thickened after being stirred with a spatula after being placed; and the grade in the pencil test is 4, i.e. the pigment stability is reduced.

[0132] Finally, it should be noted that the above examples are used to illustrate the technical solutions of the present application and are not intended to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A high-coverage yellow acrylic topcoat, characterized in that, The topcoat comprises the following components by weight percentage: 25-50% Polymer Resin A, 10-28% Polymer Resin B, 0.4-1% Wetting and Dispersing Agent, 0.1-0.5% Defoamer, 12-20% Pigment Composition, 1.5-6% Filler, 0.1-0.3% pH Adjuster, 2.5-5% Film-Forming Aid, 0.6-2% Anti-Settling Agent, 0.3-0.6% Thickener, Balance: Water; The polymer resin A comprises an acrylic copolymer emulsion, the polymer resin B comprises polystyrene microspheres, and the mass ratio of polymer resin A to polymer resin B is (5-8):(2-5). The pigment composition comprises modified zinc oxide and an inorganic-organic composite yellow pigment; The wetting and dispersing agent comprises a nonionic surfactant of fatty alcohol alkyl ethers and a styrene maleic anhydride derivative in a mass ratio of (1-2):(4-8); The preparation method of the polymer resin B includes the following steps: (1) Add styrene-maleic anhydride copolymer and ammonia water to deionized water and heat to 40-60℃ and stir until the system is clear and transparent. Then add some styrene and continue to heat to 70-90℃ and stir for 30-60 min. Then add some initiator aqueous solution and react until the system turns blue. Keep warm for 30-60 min to obtain a mixed solution. (2) Mix the remaining styrene and divinylbenzene evenly to obtain monomer solution 1. Take part of monomer solution 1 and add it to vinyltriisopropoxysiloxane and mix evenly to obtain monomer solution 2. (3) Add monomer solution 1 and another part of the initiator aqueous solution to the mixed solution in step (1). After the monomer solution 1 is added, add monomer solution 2. After the addition is completed, continue the reaction for 40-70 min. Then add the remaining part of the initiator aqueous solution and keep warm for 60-90 min. Then cool down and discharge the material to obtain polystyrene microspheres.

2. The high-coverage yellow acrylic topcoat according to claim 1, characterized in that, Based on the total mass of the reacting monomers, the styrene-maleic anhydride copolymer comprises 15-30% by mass, divinylbenzene comprises 1-4% by mass, vinyltriisopropoxysiloxane comprises 0.5-2.5% by mass, and the initiator comprises 1-2% by mass. And / or, in the aqueous solution of the initiator, the initiator has a mass percentage of 1.5-2.5%, and the initiator is 2,2'-azobisisobutylamidine dihydrochloride; And / or, the number-average relative molecular weight of the styrene-maleic anhydride copolymer is 2500-3500; And / or, in step (1), a portion of the styrene accounts for 15-25% of the total mass of the styrene; in step (3), another portion of the initiator aqueous solution accounts for 60-70% of the total mass of the initiator aqueous solution, and the remaining portion of the initiator aqueous solution accounts for 10-20% of the total mass of the initiator aqueous solution.

3. The high-coverage yellow acrylic topcoat according to claim 1, characterized in that, The method for preparing the modified zinc oxide includes the following steps: Nano zinc oxide was added to the modified solution, ultrasonically dispersed, and then heated to react. After the reaction was completed, the solution was filtered, washed, and dried to obtain modified zinc oxide. The modified solution is prepared by adding 3-glycidyl etheroxypropyltriethoxysilane to a 95% ethanol aqueous solution, mixing thoroughly, and then adjusting the pH to 3-4.

4. The high-coverage yellow acrylic topcoat according to claim 3, characterized in that, The mass percentage of the 3-glycidyl etheroxypropyltriethoxysilane is 0.5-2% based on the mass of nano-zinc oxide. And / or, in the modified solution, the mass percentage of 3-glycidyl etheroxypropyltriethoxysilane is 0.5-1%; And / or, the ultrasonic dispersion time is 30-60 min; And / or, the heating reaction is carried out at a temperature of 40-60°C for a time of 90-150 min; And / or, the drying temperature is 80-100°C.

5. The high-coverage yellow acrylic topcoat according to claim 1, characterized in that, The pigment composition further includes at least one of iron oxide yellow, rutile titanium chromium pigment, and rutile titanium nickel pigment.

6. The high-coverage yellow acrylic topcoat according to claim 1, characterized in that, The defoamer includes a modified silicone defoamer containing hydrophobic particles; And / or, the filler includes at least one of wollastonite and aluminosilicate zeolite; And / or, the pH adjuster includes N,N-dimethylethanolamine; And / or, the film-forming aid includes at least one of alcohol ester dodecyl and ethylene glycol butyl ether; And / or, the anti-settling agent comprises water-based polyamide wax; And / or, the thickener includes a nonionic polyurethane thickener.

7. The high-coverage yellow acrylic topcoat according to claim 6, characterized in that, The film-forming aid comprises dodecayl alcohol ester and ethylene glycol butyl ether in a mass ratio of 1:(0.5-1.5); And / or, the anti-settling agent is a pre-prepared water slurry of waterborne polyamide wax, wherein the mass ratio of waterborne polyamide wax to water in the anti-settling agent is 1:(2-4).

8. The method for preparing a high-octane yellow acrylic topcoat according to any one of claims 1-7, characterized in that, The preparation method includes the following steps: (1) After mixing water and wetting and dispersing agent for the first dispersion, add some defoamer for the second dispersion, then add pigment composition and filler for the third dispersion to obtain slurry, and then grind the slurry to obtain refined slurry; (2) Mix polymer resin A and polymer resin B for the fourth dispersion, then add pH adjuster for the fifth dispersion to obtain a mixture; (3) Add the refined slurry from step (1) to the mixture in step (2) for sixth dispersion, then add the anti-settling agent for seventh dispersion, then add the remaining defoamer and film-forming aid for eighth dispersion, and finally add the thickener in batches to adjust the viscosity and filter to obtain a high-coverage yellow acrylic topcoat.

9. The preparation method according to claim 8, characterized in that, The fineness of the refined slurry is ≤30μm; And / or, the viscosity is 85-90 KU.

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