High-covering yellow acrylic finishing paint and preparation method thereof

Abstract

The invention discloses a high-covering yellow acrylic finishing paint and a preparation method thereof, and belongs to the technical field of coatings. According to the high-covering yellow acrylic finishing paint provided by the invention, the covering power, the color contrast property and the dispersion stability of the finishing paint can be effectively improved by selecting the components with proper mass percent and mutually cooperating the components, and the early-stage water resistance is excellent. Meanwhile, the preparation method of the finish paint provided by the invention is simple to operate, does not need special equipment, and is beneficial to actual production.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and in particular relates to a high-hiding yellow acrylic topcoat and a preparation method thereof. Background Art

[0002] The hiding power of a paint refers to the ability of a paint to cover a substrate or base color. It is related to the scattering and absorption of light by the pigment and is an important property of the paint. Among common paints, yellow, orange and red paints show poor hiding power, especially yellow. Compared with traditional organic pigments, lead-chromium pigments have lower oil absorption values, better dispersibility, and less impact on the production process of water-based paints. Some lead-chromium pigments have a higher refractive index, such as chrome yellow and molybdenum chromium red, which are easier to obtain hiding power. However, they contain hexavalent chromium, lead, cadmium, etc., which will pollute the environment and endanger human health. Lead-free pigments are gradually being used to replace lead-chromium pigments. At present, the poor hiding power of yellow paint is a technical problem in the paint industry. Titanium dioxide has a high hiding power. Adding a certain amount of white powder can effectively improve the hiding power of yellow paint, but the amount of titanium dioxide added should not be too high, otherwise it will dilute the color, especially dark yellow paint. In addition, increasing the thickness of the paint film, increasing PVC, and using a colored primer or intermediate paint with a color similar to the topcoat are also often used to improve the hiding power of yellow paint. However, these methods will bring inconvenience to construction or production, and the cost is relatively high. Summary of the invention

[0003] The object of the present invention is to overcome the deficiencies of the above-mentioned 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 object, in a first aspect of the present invention, the present invention provides a high-hiding yellow acrylic topcoat, the topcoat comprising the following components in mass percentage:

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

[0006] The polymer resin A comprises an acrylic copolymer emulsion, 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 an inorganic-organic composite yellow pigment;

[0008] The wetting and dispersing agent comprises a nonionic surfactant of 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 topcoat provided by the invention can effectively improve the hiding power, color development and dispersion stability of the topcoat by selecting components with appropriate mass percentages, and the components cooperate with each other, and the topcoat has excellent early water resistance.

[0010] Specifically, the present invention selects polymer resin A and polymer resin B of specific types and mass percentage ranges to be compounded in a specific mass ratio, which can effectively increase the microscopic roughness of the paint film formed by the topcoat. The increased surface roughness of the paint film can enhance the scattering of light, thereby reducing the light transmittance of the topcoat; specifically, the polymer resin B selected by the present invention is polystyrene microspheres, which have a core-shell structure, a high film-forming temperature, a large surface roughness, and the grafted substances on its surface 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. At the same time, it can also be well compounded with the polymer resin A, and the film-forming property of the paint film is good. The pigment composition selected by the present invention is compounded with modified zinc oxide and an inorganic-organic composite yellow pigment. Not only is the type of the selected pigment environmentally friendly and safe, but it also has good thermal stability, weather resistance and chemical resistance, and can also effectively improve the hiding power of the topcoat. In addition, the type of the wetting and dispersing agent selected by the present invention has an excellent synergistic effect, has good wettability and dispersibility for the pigment, improves floating color and blooming, and can also improve the stability of the pigment, thereby effectively improving the color development effect of the topcoat, reducing the covering thickness of the coating, and improving the stability of the topcoat.

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

[0012] More preferably, the minimum film-forming temperature of the acrylic copolymer emulsion is 20-40°C.

[0013] For example, the acrylic copolymer emulsion may be obtained from BASF New Materials Co., Ltd. PRO1552, MT-3628 of Guangdong Landburg New Materials Co., Ltd., and Wanhua Chemical Group Co., Ltd. 0624, etc.

[0014] Exemplarily, the mass ratio of the polymer resin A and the polymer resin B may be any point value or any two point range values ​​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 nonionic surfactant of fatty alcohol alkyl ether and the styrene maleic anhydride derivative can be any point value or any two point range values ​​between (1-2): (4-8), such as 1:4, 1:6, 1:8, 2:4, 2:6, 2:8, etc.

[0016] Illustratively, the fatty alcohol alkyl ether nonionic surfactant may be NOVELUTION KG4, NOVELUTION KG5, NOVELUTION K08, etc. produced by Sasol (China) Chemical Co., Ltd.; the styrene maleic anhydride derivative may be Gresssol DP1030, Gresssol DP2200, Gresssol DP1190 produced by Yueyang Kaimen Water-based Additive Co., Ltd., DISPERBYK 2010 produced by BYK Chemical, etc.

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

[0018] (1) adding styrene maleic anhydride copolymer and ammonia water to deionized water, heating to 40-60° C. and stirring until the system is clear and transparent, then adding part of styrene, continuing to heat to 70-90° C. and stirring for 30-60 min, then adding part of the initiator aqueous solution to react until the system turns blue and then keeping the temperature for 30-60 min to obtain a mixed solution;

[0019] (2) mixing the remaining styrene and divinylbenzene uniformly to obtain a monomer solution 1, taking a portion of the monomer solution 1 and adding it to vinyl triisopropoxysiloxane and mixing uniformly to obtain a 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), and monomer solution 2 is added dropwise after the addition of monomer solution 1 is completed. The reaction is continued for 40-70 minutes, and then the remaining part of the initiator aqueous solution is added and kept warm for 60-90 minutes, and then the temperature is lowered and the material is discharged to obtain polystyrene microspheres.

[0021] The present invention has been found that the polystyrene microspheres prepared by the preparation method provided by the present invention are of a core-shell structure, and an organic siloxane segment is grafted on the surface; on the one hand, the surface roughness of the prepared polystyrene microspheres is relatively large, thereby increasing the roughness of the paint film surface, thereby increasing the scattering of light, reducing the transmittance of the paint film, and improving the hiding power of the paint film; on the other hand, the organic siloxane segment on the surface of the polystyrene microspheres will migrate to the surface of the paint film within a certain range, forming a heterogeneous structure on the surface of the paint film, 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 invention, based on the total mass of the reactive monomers, 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 the initiator is 1-2%.

[0023] It should be noted that the reactive monomers include styrene, divinylbenzene and vinyl triisopropoxysiloxane.

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

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

[0026] For example, the styrene maleic anhydride copolymer may be SER11 produced by Yueyang Kaimen Waterborne Additive Co., Ltd., whose number average relative molecular mass, weight average relative molecular mass and acid value are 2500-3500, 4500-5500 and 480 mgKOH / g, respectively.

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

[0028] In the preparation method of polymer resin B, the role of adding ammonia water is 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 dissolve in water, thereby obtaining a clear and transparent system.

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

[0030] Adding nano zinc oxide to the modified solution for ultrasonic dispersion and then heating for reaction, filtering, washing and drying after the reaction is completed to obtain modified zinc oxide;

[0031] The preparation method of the modified solution is as follows: 3-glycidyloxypropyltriethoxysilane is added into a 95% ethanol aqueous solution, the mixture is evenly mixed, and then the pH value is adjusted to 3-4.

[0032] The present invention has found that the modified zinc oxide prepared by modifying nano zinc oxide using the method provided by the present invention 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 of the present invention, the mass percentage of the 3-glycidyloxypropyltriethoxysilane is 0.5-2% based on the mass of the nano zinc oxide.

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

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

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

[0037] As a preferred embodiment of the topcoat of the present invention, the drying temperature is 80-100°C.

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

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

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

[0041] The present invention has found that different selections and mass ratios of components in the pigment composition will affect the coloring effect of the topcoat. By selecting the above-mentioned type of pigment composition, wherein a variety of highly opaque inorganic pigments such as modified zinc oxide, rutile titanium chromium pigments and yellow iron oxide are added to the inorganic-organic composite yellow pigment, the covering power of the topcoat can be effectively improved, the dosage is low, and the color tone has little effect. At the same time, the compounded wetting and dispersing agent has a synergistic effect on the color development of the yellow pigment, so that the pigment composition can present a distinct yellow color after being wetted and dispersed.

[0042] For example, the rutile titanium chromium pigment is a rutile crystal structure modified by titanium dioxide, and may be HEUCODUR YELLOW 9064, HEUCODUR YELLOW 9116, HEUCODUR YELLOW 3R, HEUCODUR YELLOW 253, etc., produced by Faber Hertz Shanghai Co., Ltd.

[0043] For example, the yellow iron oxide may be Yellow 311, Yellow 313, Yellow 315, Yellow 810, etc., produced by Tongling Ruilai Technology Co., Ltd.

[0044] Illustratively, the inorganic-organic composite yellow pigment is a colored titanium pigment composited with an organic pigment and an inorganic titanium yellow pigment, and may be YELLOW T-53-09, YELLOW T-84-03, YELLOWY-84-01, YELLOW Y-34-70, etc. manufactured by Guangzhou Jilang Environmental Protection Technology Co., Ltd.

[0045] As a preferred embodiment of the topcoat of the present invention, the defoamer includes a modified silicone defoamer containing hydrophobic particles.

[0046] For example, the defoaming agent may be Coadd from Puwei (Shanghai) New Material Technology Co., Ltd. TM DF-9040.

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

[0048] Exemplarily, the wollastonite may be SC-800 produced by Guangdong Fujian Building Materials (Jiaoling) Refining Co., Ltd., which has an average particle size of 3.5 μm and a whiteness of ≥89%.

[0049] For example, the aluminum silicate zeolite may be ZEOCROS CG180 produced by Guangzhou Dongbo Chemical Co., Ltd., which has an average particle size of 1.2 μm and a specific gravity of 2 g / mL.

[0050] As a preferred embodiment of the topcoat of the present invention, the pH adjuster includes N,N-dimethylethanolamine.

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

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

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

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

[0056] Preferably, the anti-settling agent is a prefabricated water slurry of 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 prefabricated water slurry of 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 may be HP-337 from Hangzhou Haidisi New Materials Co., Ltd.

[0059] As a preferred embodiment of the topcoat of the present invention, the thickener includes a non-ionic polyurethane thickener.

[0060] For example, the thickener may be U505.

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

[0062] (1) mixing water and a wetting and dispersing agent for a first dispersion, adding a portion of a defoaming agent for a second dispersion, then adding a pigment composition and a filler for a third dispersion to obtain a slurry, and then sand-grinding the slurry to obtain a refined slurry;

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

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

[0065] The preparation method of the topcoat provided by the invention is simple to operate and is beneficial to actual production.

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

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

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

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

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

[0071] The high-hiding yellow acrylic topcoat provided by the present invention can effectively improve the hiding power, color development and dispersion stability of the topcoat by selecting components with appropriate mass percentages, and the components cooperate with each other, and the early water resistance is excellent. At the same time, the preparation method of the topcoat provided by the present invention is simple to operate, does not require special equipment, and is conducive to actual production. DETAILED DESCRIPTION

[0072] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0073] The reagents, methods and equipment used in the present invention, unless otherwise specified, are all conventional reagents, methods and equipment in the art; and the components used in the embodiments 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, homemade, the preparation method includes the following steps:

[0077] (1) Add 10g of styrene maleic anhydride copolymer SMA (SER11, Yueyang Kaimen Water-based Additive Co., Ltd.), 74g of deionized water and 3.5g of ammonia water in a 250mL four-necked flask, heat to 50°C under stirring, and stir until the system becomes clear and transparent. Take 0.75g of 2,2'-azobisisobutylamidine dihydrochloride V50 and 36.75g of deionized water in a beaker, stir and dissolve to obtain an initiator aqueous solution. Then, add 5g of styrene and 20% initiator aqueous solution, stir for 30min, then heat to 85°C. When the reaction system turns blue, keep warm for 30min;

[0078] (2) 43 g of styrene and 1 g of divinylbenzene were added to a beaker, and the mixture was uniformly mixed to obtain a monomer solution 1. One third of the monomer solution 1 was added with 1 g of vinyl triisopropoxysiloxane, and the mixture was uniformly mixed to obtain a monomer solution 2.

[0079] (3) adding monomer solution 1 and 65% initiator aqueous solution to the flask simultaneously, and starting to add monomer solution 2 after the addition of monomer solution 1 is completed. The addition time of the monomer solution and the initiator aqueous solution is about 180 minutes;

[0080] (4) After the addition is completed, the reaction is continued for 60 minutes, and then the remaining portion of the initiator aqueous solution is added and kept warm for 60 minutes. When the temperature drops to room temperature, the material is discharged to obtain polystyrene microspheres.

[0081] Wetting and dispersing agent 1: a mixture of a nonionic surfactant of fatty alcohol alkyl ether (NOVELUTION KG4, Sasol China Chemical Co., Ltd.) and a styrene maleic anhydride derivative (Gresssol DP1030, Yueyang Kaimen Waterborne Additive Co., Ltd.) in a mass ratio of 1:7.

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

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

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

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

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

[0087] Wetting and dispersing agent 7: The difference from wetting and dispersing agent 1 is that NOVELUTION KG4 is replaced by NOVELUTION K08, and Gresssol DP1190 is replaced by Gresssol DP1030;

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

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

[0090] Defoamer: Modified silicone defoamer 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, Faber Hertz Shanghai Co., Ltd.), yellow iron oxide (Yellow 311, Tongling Ruilai Technology Co., Ltd.), and inorganic-organic composite yellow pigment (YELLOW T-53-09, Guangzhou Jilang Environmental Protection Technology Co., Ltd.) in a ratio of 7:5:1:65;

[0092] The modified zinc oxide is homemade, and the preparation method comprises the following steps:

[0093] Add 0.5 g of 3-glycidyloxypropyltriethoxysilane to 100 g of 95% ethanol, stir evenly, add acetic acid dropwise until the pH is 3-4, add 50 g of nano zinc oxide, ultrasonically disperse for 30 minutes, then react for 120 minutes at 50°C with mechanical stirring, cool to room temperature, filter, wash with 95% ethanol 5 times, and finally dry in an oven at 100°C to obtain modified zinc oxide.

[0094] Pigment composition 2: The difference from pigment composition 1 is that no rutile titanium chromium pigment is added, and a mixture of modified zinc oxide, yellow iron oxide (Yellow 311, Tongling Ruilai Technology Co., Ltd.), and inorganic-organic composite yellow pigment (YELLOW T-53-09, Guangzhou Jilang Environmental Protection Technology Co., Ltd.) is formed in a ratio of 7.5:1:69.5;

[0095] Pigment composition 3: The difference from pigment composition 1 is that zinc oxide is used instead of modified zinc oxide.

[0096] Filler: a mixture of wollastonite (SC-800, Guangfu Building Materials (Jiaoling) Refining Co., Ltd.) and aluminum silicate zeolite (ZEOCROSCG180, Guangzhou Dongbo Chemical Co., Ltd.) in a mass ratio of 1:1.

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

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

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

[0100] Thickener: nonionic polyurethane, U505, Wanhua Chemical Group Co., Ltd.

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

[0102] The embodiment of the present invention provides a high-hiding yellow acrylic topcoat, the components (mass percentage) of the topcoat are shown in Table 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 topcoat provided in Example 1 comprises the following steps:

[0112] (1) Water and a wetting dispersant were added to a dispersion kettle, and the mixture was dispersed at 600 rpm for 6 min. 40% of a defoaming agent was then added and the mixture was dispersed for 12 min.

[0113] (2) adding the pigment composition 1 and the filler to the dispersion kettle of step (1) at a speed of 200 rpm, adjusting the speed to 1200 rpm for dispersion for 22 min, and then sand-grinding the slurry to a slurry fineness of ≤30 μm;

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

[0115] (4) Add the slurry of step (2) to the dispersion kettle of step (3), disperse at a speed of 800 rpm for 12 minutes, then add the anti-settling agent, and continue to disperse for 12 minutes. Then, add 60% of the defoamer and the film-forming aid in sequence, and disperse at 1000 rpm for 12 minutes. Finally, add the thickener in small amounts at a speed of 1000 rpm, adjust the viscosity of the paint to 85-90 KU, filter with a 200-mesh filter, collect the filtrate, and obtain a high-hiding yellow acrylic topcoat.

[0116] The preparation methods of the high hiding yellow acrylic topcoats provided in Examples 2-13 and Comparative Examples 1-5 are consistent with that in Example 1.

[0117] Effect example

[0118] The effect examples of the present invention verify the performance of the high hiding yellow acrylic topcoat prepared by Examples 1-13 and Comparative Examples 1-5, including the following aspects:

[0119] (1) Liquid paint state: After sealing the paint sample, place it in a 50℃ oven for 14 days, take it out and cool it to room temperature, and then observe its appearance to see if there is floating color or floating. Use 1-8 levels to assess the degree of floating color and floating: 1 means almost no floating color or floating; 8 means very serious floating color and floating; the middle 2-7 levels are rated according to the severity of floating color and floating. Then stir it with a spatula and observe if there is any abnormality.

[0120] (2) Color development test: After the sample paint is stirred evenly, it is scraped on black and white cardboard using a 200μm wire rod applicator. The wet film after scraping is placed at room temperature to dry for 24 hours, and the color is compared visually. The closer the color is to the main color system (national standard dark yellow), the better the color development. The color development is rated on a 1-8 scale: 1 indicates a very light color; 8 indicates a dark color, very close to the main color system; the intermediate 2-7 levels are rated according to the depth of the color.

[0121] (3) Thickness of hiding coating: Use air spray to spray on white and black cardboard until the paint film completely covers the black and white cardboard. Then, place the paint film at room temperature to dry for 24 hours, and use an ultrasonic coating thickness gauge to test the thickness of the paint film, i.e. the thickness of the hiding coating.

[0122] (4) Finger rubbing test: After the paint sample is stirred evenly, use a 250μm wire rod applicator to scrape and apply it on black and white cardboard. Before the paint film is dry, use the fingertips to gently rub the same area on the paint film 20 times. Then, after the paint film is left to dry at room temperature for 24 hours, visually compare the color difference between the finger rubbing area and the non-finger rubbing area. The smaller the color difference, the better the dispersion stability of the pigment. The color difference is graded from 1 to 8: 1 means almost no color difference; 8 means a very large color difference; the intermediate 2-7 levels are rated according to the size of the color difference.

[0123] (5) Early water resistance: Plates were prepared and tested according to Table 5 of HG / T 5176-2017. The yellow acrylic water-based paint of the present invention was used as a topcoat, and the matching primer was JT-205D produced by Guangzhou Jitai Chemical Co., Ltd.

[0124] The results obtained are shown in Table 4;

[0125] Table 4

[0126]

[0127]

[0128] It can be seen from Table 4 that when the technical solution provided by the present invention is adopted, the obtained product has excellent comprehensive effects, which is reflected in that there is almost no floating color after placement, excellent color development, small thickness of the covering coating, excellent dispersion stability of the pigment, and good early water resistance; specifically, the liquid paint grade of the obtained product is below grade 4, and there is no abnormality after scraper stirring; the color development test is above grade 5; the thickness of the covering coating does not exceed 105 μm, the finger rubbing test is all grade 3 or below, and the early water resistance is all above 24 hours;

[0129] It can be seen from Example 1, Examples 3-5 and Comparative Examples 1-2 that the mass ratio between polymer resin A and polymer resin B in the topcoat and the added mass percentage will affect the comprehensive performance of the product. When the added mass fraction of polymer resin B in Comparative Example 1 is too small, the covering thickness of the paint film is higher than 110 μm, that is, the covering power of the paint film is poor; when the added mass percentage of polymer resin B in Comparative Example 2 is too much, the obtained product liquid paint is in poor condition, and gumming will occur when stirred with a spatula after standing.

[0130] It can be seen from Example 1, Examples 6-10 and Comparative Examples 3-4 that the mass ratio of the wetting and dispersing agent will also affect the comprehensive performance of the product. When the proportion of Gresssol DP1030 in the wetting and dispersing agent of Comparative Example 3 is too high, the hiding power of the obtained topcoat is slightly improved, but the early water resistance is poor; when the proportion of NOVELUTION KG4 in the wetting and dispersing agent of Comparative Example 4 is too high, the hiding power of the obtained topcoat is also improved, but the early water resistance of the paint film is significantly reduced, and the early water resistance time is less than 24h;

[0131] It can be seen from Example 1 and Comparative Example 5 that the type of pigment composition will also affect the comprehensive performance of the product. When the pigment composition used in Comparative Example 5 is not provided by the present invention, the obtained product liquid paint is in poor condition, and coarsening will occur when stirred with a scraper after being placed; and the grade in the finger grinding test is 4, that is, the pigment stability is reduced.

[0132] Finally, it should be noted that the above embodiments are intended to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A high hiding yellow acrylic topcoat, characterized in that: The topcoat comprises the following components in percentage by mass: 25-50% polymer resin A, 10-28% polymer resin B, 0.4-1% wetting and dispersing agent, 0.1-0.5% defoaming agent, 12-20% pigment composition, 1.5-6% filler, 0.1-0.3% pH regulator, 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 the polymer resin A to the 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 ether and a styrene maleic anhydride derivative in a mass ratio of (1-2):(4-8).

2. The topcoat according to claim 1, characterized in that The preparation method of the polymer resin B comprises the following steps: (1) adding styrene maleic anhydride copolymer and ammonia water to deionized water, heating to 40-60° C. and stirring until the system is clear and transparent, then adding part of styrene, continuing to heat to 70-90° C. and stirring for 30-60 min, then adding part of the initiator aqueous solution to react until the system turns blue and then keeping the temperature for 30-60 min to obtain a mixed solution; (2) mixing the remaining styrene and divinylbenzene uniformly to obtain a monomer solution 1, taking a portion of the monomer solution 1 and adding it to vinyl triisopropoxysiloxane and mixing uniformly to obtain a monomer solution 2; (3) Monomer solution 1 and another part of the initiator aqueous solution are added dropwise to the mixed solution in step (1), and monomer solution 2 is added dropwise after the addition of monomer solution 1 is completed. The reaction is continued for 40-70 minutes, and then the remaining part of the initiator aqueous solution is added and kept warm for 60-90 minutes, and then the temperature is lowered and the material is discharged to obtain polystyrene microspheres.

3. The topcoat according to claim 2, characterized in that At least one of the following: a. Based on the total mass of the reactive monomers, the mass percentage of styrene maleic anhydride is 15-30%, the mass percentage of divinylbenzene is 1-4%, the mass percentage of vinyl triisopropoxysiloxane is 0.5-2.5%, and the mass percentage of the initiator is 1-2%; b. In the aqueous initiator solution, the mass percentage of the initiator is 1.5-2.5%, and the initiator is 2,2'-azobisisobutylamidine dihydrochloride; c. The number average relative molecular weight of the styrene maleic anhydride copolymer is 2500-3500; d. In the step (1), part of the styrene accounts for 15-25% of the total mass of the styrene; in the step (3), another part of the initiator aqueous solution accounts for 60-70% of the total mass of the initiator aqueous solution, and the remaining part of the initiator aqueous solution accounts for 10-20% of the total mass of the initiator aqueous solution.

4. The topcoat according to claim 1, characterized in that The preparation method of the modified zinc oxide comprises the following steps: Adding nano zinc oxide to the modified solution for ultrasonic dispersion and then heating for reaction, filtering, washing and drying after the reaction is completed to obtain modified zinc oxide; The preparation method of the modified solution is as follows: 3-glycidyloxypropyltriethoxysilane is added into a 95% ethanol aqueous solution, the mixture is evenly mixed, and then the pH value is adjusted to 3-4.

5. The topcoat according to claim 4, characterized in that The mass percentage of the 3-glycidyloxypropyltriethoxysilane is 0.5-2% based on the mass of the nano zinc oxide; And / or, in the modified solution, the mass percentage of 3-glycidyloxypropyltriethoxysilane is 0.5-1%; And / or, the ultrasonic dispersion time is 30-60 min; And / or, the heating reaction temperature is 40-60°C and the time is 90-150min; And / or, the drying temperature is 80-100°C.

6. The topcoat according to claim 1, characterized in that The pigment composition further comprises at least one of yellow iron oxide, rutile titanium chromium pigment and rutile titanium nickel pigment.

7. The topcoat according to claim 1, characterized in that The defoamer includes a modified silicone defoamer containing hydrophobic particles; And / or, the filler comprises at least one of wollastonite and aluminum silicate zeolite; and / or, the pH adjuster comprises N,N-dimethylethanolamine; And / or, the film-forming aid includes at least one of alcohol ester dodecaned 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.

8. The topcoat according to claim 7, characterized in that The film-forming aid comprises alcohol ester dodecanedrine and ethylene glycol butyl ether in a mass ratio of 1:(0.5-1.5); And / or, the anti-settling agent is a prefabricated water slurry of 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).

9. The method for preparing a topcoat according to any one of claims 1 to 8, wherein: The preparation method comprises the following steps: (1) mixing water and a wetting and dispersing agent for a first dispersion, adding a portion of a defoaming agent for a second dispersion, then adding a pigment composition and a filler for a third dispersion to obtain a slurry, and then sand-grinding the slurry to obtain a refined slurry; (2) mixing polymer resin A and polymer resin B for a fourth dispersion, and then adding a pH adjuster for a fifth dispersion to obtain a mixture; (3) adding the refined slurry in step (1) to the mixture in step (2) for the sixth dispersion, then adding the anti-settling agent for the seventh dispersion, and then adding the remaining part of the defoamer and the film-forming aid for the eighth dispersion, and finally adding the thickener in batches to adjust the viscosity and filtering to obtain the topcoat.

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

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