Water-based automobile silver powder paint with high brightness and high fine and smooth feeling as well as preparation method and application of water-based automobile silver powder paint

Abstract

The invention relates to a high-brightness and high-fineness water-based automobile silver powder paint as well as a preparation method and application thereof. The water-based automobile silver powder paint provided by the invention is prepared from the following components in percentage by weight: an acrylic acid modified polyurethane dispersion, an organic silicon-polyurethane-acrylate ternary copolymer emulsion, amino resin, an alkynediol surfactant, a thickening agent, superfine nano barium sulfate slurry, silicon dioxide coated aluminum silver slurry, a dispersing agent A, a flatting agent, a defoaming agent, N, N-dimethylformamide, a dispersing agent B, a dispersing agent C, a dispersing agent D, a dispersing agent E and a dispersing agent E, the cleaning agent is prepared from N, N-dimethylethanolamine, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, ethylene glycol isooctyl ether and deionized water. The arrangement effect of the silver powder of the water-based automobile silver powder paint is remarkably improved, so that the water-based automobile silver powder paint has high stability, high brightness and high fineness at the same time, and the basic performance of an original automobile factory paint film can be met.

Description

Technical Field

[0001] The present invention belongs to the technical field of automotive coatings, and particularly relates to a high-brightness and high-fineness waterborne automotive silver paint, and a preparation method and application thereof. Background Art

[0002] Currently, the automotive industries at home and abroad, especially the new energy vehicle industry, are developing at an unprecedented rapid pace. Correspondingly, the supporting automotive coating industry has also shown an unprecedented rapid development trend. Generally speaking, automotive body coatings are mainly divided into solid color paints and metallic pigment paints (commonly known as silver paints). Metallic pigment paints contain metal components such as aluminum powder (commonly known as silver powder), and can exhibit a unique flash decorative effect, so the proportion in automotive painting is increasing day by day. In addition, in response to environmental protection requirements, more and more metallic pigment paints are gradually changing from traditional solvent-based to water-based.

[0003] The particle size of silver powder plays a crucial role in the brightness and fineness of the silver paint film. Usually, in order to give the paint film a better delicate touch rather than an obvious granular feeling, silver powder with a smaller particle size is selected. However, the reduction of the silver powder particle size will lead to a weakening of its light reflection effect, thereby reducing the brightness of the paint film and affecting the display of the metallic texture. Therefore, to achieve the visual effect of the paint film having both high brightness and high fineness, the coating formulation needs to have excellent silver powder arrangement ability, enhance the directional arrangement of medium and small particle size silver powder in the paint film, so as to improve the directional reflection of light, and finally achieve a double improvement in high brightness and angle-dependent color effect.

[0004] Currently, waterborne automotive silver paints have the following main problems: Under the existing technical conditions, the silver powder arrangement effect of waterborne silver paints is usually not good, and additional alignment aids such as CAB, EVA wax, polyamide wax, and lithium magnesium silicate need to be added to improve it. For example, Chinese patent document CN103319965A discloses a waterborne metallic flash paint for automobiles and its preparation method, which discloses the use of anti-settling agents such as Viscalex HV30 to improve the silver powder arrangement effect; secondly, Chinese patent document CN111218183A discloses a preparation method of a high-whiteness flash metallic paint, which discloses the use of polyamide wax and EVA wax to improve the arrangement of aluminum silver paste, thereby improving the brightness of the paint film. However, at present, the use conditions of some alignment aids are relatively harsh, or the effect of improving the arrangement is average and a large amount is required; or the stability is poor, and it is easy to cause problems such as gelation of the paint and large changes in viscosity after storage, affecting the use and performance of the paint.

[0005] In summary, in view of the defects of poor silver powder arrangement effect, and the difficulty in balancing brightness and fineness in the existing waterborne automotive silver powder paint, a waterborne automotive silver powder paint with excellent arrangement effect, high brightness and high fineness is developed. It is of great significance to improve the overall performance of automotive body coatings and meet the market demand for high-quality automotive coatings. Summary of the Invention

[0006] Aiming at the deficiencies of the existing technology, the present invention aims to provide a waterborne automotive silver powder paint with high brightness and high fineness, its preparation method and application. The present invention uses ultrafine nano barium sulfate and organosilicon-polyurethane-acrylate terpolymer emulsion as a new type of directional arrangement aid to improve the arrangement effect of the waterborne silver powder paint, making it have high stability, high brightness and high fineness at the same time, and can meet the basic performance of automotive original factory paint films.

[0007] To achieve the above object, the present invention adopts the following technical solutions: The first object of the present invention is to provide a waterborne automotive silver powder paint with high brightness and high fineness, which includes the following raw materials in weight percentage: 12-18 parts of acrylic-modified polyurethane dispersion, 20-30 parts of organosilicon-polyurethane-acrylate terpolymer emulsion, 2-5 parts of amino resin, 0.5-1.5 parts of alkynediol surfactant, 0.5-2 parts of thickener, 2-5 parts of ultrafine nano barium sulfate slurry, 4-6 parts of silica-coated aluminum silver paste, 0.1-1 part of dispersant A, 0.05-0.5 part of leveling agent, 0.1-1 part of defoaming agent, 0.5-2 parts of N,N-dimethylethanolamine, 5-10 parts of ethylene glycol monobutyl ether, 1-5 parts of propylene glycol monobutyl ether, 1-5 parts of ethylene glycol isooctyl ether, and 20-40 parts of deionized water.

[0008] Preferably, the mass ratio of the acrylic-modified polyurethane dispersion to the organosilicon-polyurethane-acrylate terpolymer emulsion is 1:(1.3-2.8).

[0009] Preferably, the acrylic-modified polyurethane dispersion is at least one of Zahn DAOTAN TW6466 / 36WA, DAOTAN TW6462 / 36WA and DAOTAN TW6464 / 36WA; the organosilicon-polyurethane-acrylate terpolymer emulsion is Dolphin New Materials Dolphin 1830; the amino resin is at least one of Zahn CYMEL 325 and CYMEL 327; the alkynediol surfactant is at least one of Evonik Surfynol 440, Surfynol 420 and Surfynol 104 DPM; the thickener is at least one of BASF Viscalex HV 30 and RHEOVIS AS 1130.

[0010] Preferably, by weight percentage, the ultrafine nano-barium sulfate slurry comprises the following components: 30-50 parts of nano-barium sulfate, 10-30 parts of dispersant B, and 20-40 parts of deionized water.

[0011] Preferably, the dispersant B is at least one of BYK-192 and BYK-190 of BYK; the nano-barium sulfate is at least one of BARIFINE BF-20 of Sakai Chemical Industry Co., Ltd. and FB-30 of Hongzhi New Materials Co., Ltd.

[0012] Preferably, the preparation method of the ultrafine nano-barium sulfate slurry comprises: (1) Sequentially put the formulated amount of deionized water and dispersant B into a stirring tank. Under the condition of 300-600 revolutions per minute, after dispersing for 5-15 minutes, then put the formulated amount of nano-barium sulfate. Under the condition of 500-700 revolutions per minute, disperse for more than 30 minutes; (2) Transfer all the liquid materials obtained in step (1) to a horizontal sand mill, and put in high-purity zirconia ceramic microbeads. The mass ratio of the high-purity zirconia ceramic microbeads to the liquid materials obtained in step (1) is (1-1.5):1. Under the condition of 2500-3500 revolutions per minute, sand mill for 1.5-2.5 h. When the fineness of the liquid materials is detected to be <5 μm, continue to keep sand milling for more than 30 minutes, and then discharge to obtain the ultrafine nano-barium sulfate slurry.

[0013] Preferably, the horizontal sand mill is LMZ-05C, manufactured by NETZSCH-Gerätebau GmbH; the particle size of the high-purity zirconia ceramic microbeads is 0.3-0.6 mm.

[0014] Preferably, the silica-coated aluminum silver paste is Anhui Xuyang 3016A water-based aluminum silver paste; the dispersant A is at least one of BYK-192 and BYK-190 of BYK; the leveling agent is at least one of BYK-381, BYK-345 and BYK-347 of BYK; the defoaming agent is at least one of TEGO 810 of Degussa, Airex 902W of Degussa and BYK-011 of BYK.

[0015] Another object of the present invention is to provide a preparation method of the above-mentioned high-brightness and high-delicacy water-based automotive silver paint, comprising the following steps: (1) Take main cylinder A, and sequentially put the formulated amount of deionized water, N,N-dimethylethanolamine, acrylic-modified polyurethane dispersion, silicone-polyurethane-acrylate terpolymer emulsion and amino resin. Under the condition of 300-600 revolutions per minute, disperse for 15-20 minutes; (2) Sequentially put the formulated amount of propylene glycol monobutyl ether, alkynediol surfactant and defoaming agent into main cylinder A in step (1). Under the condition of 300-600 revolutions per minute, disperse for 5-15 minutes; (3) Put the formulated amount of ultrafine nano barium sulfate slurry into the main cylinder A in step (2), and disperse it for 5 - 15 minutes under the condition of 300 - 600 revolutions per minute; (4) Take another auxiliary cylinder B, and successively put the formulated amount of silica-coated aluminum silver paste, ethylene glycol monobutyl ether, and ethylene glycol isooctyl ether. After soaking for 1 - 3 hours, stir for 25 - 35 minutes to ensure no caking or agglomeration. Then, successively add the formulated amount of dispersant A and leveling agent, and stir for 25 - 35 minutes to ensure no caking or agglomeration. While stirring, put the auxiliary cylinder B into the main cylinder A in step (3), and disperse it for 15 - 20 minutes under the condition of 300 - 600 revolutions per minute; (5) Put the formulated amount of thickener into the main cylinder A in step (4), and disperse it for 25 - 35 minutes at 500 - 800 revolutions per minute; (6) Adjust the pH with N,N-dimethylethanolamine while dispersing to make the pH value within the range of 8.0 - 9.0; (7) After the pH value is adjusted, keep dispersing for 10 - 15 minutes at 300 - 600 revolutions per minute to obtain the high-brightness and high-smoothness waterborne automotive silver paint.

[0016] Another object of the present invention is to provide the application of the above-mentioned high-brightness and high-smoothness waterborne automotive silver paint in the preparation of automotive coatings or in the field of automotive coating application.

[0017] The principle and concept of the present invention: Based on the problems existing in the existing waterborne automotive silver powder paint: the arrangement effect of silver powder is usually not good, and additional alignment aids such as CAB, EVA wax, polyamide wax, lithium magnesium silicate, etc. need to be added to improve it. However, the current alignment aids have harsh usage conditions, large dosages, general alignment improvement effects, and poor stability. After use, it is easy to cause problems such as gelation of the coating and large viscosity changes after storage, which affect the use and performance of the coating. It is difficult to balance the film brightness, fineness, and stability effects of the prepared waterborne automotive silver powder paint. Based on this, the present invention has developed a high-brightness and high-fineness waterborne automotive silver powder paint. First of all, the present invention selects two main resins with strong alkali swelling properties - acrylic-modified polyurethane dispersion and organosilicon-polyurethane-acrylate terpolymer emulsion, and limits their specific proportions. The present invention has found through experiments that when the dosage of the organosilicon-polyurethane-acrylate terpolymer emulsion is too large, the film is brittle, resulting in poor mechanical properties such as impact resistance of the film; while when the dosage of the acrylic-modified polyurethane dispersion is too large, on the one hand, the formulation cost increases, and on the other hand, the silver powder alignment effect decreases. The present invention has proven through research that only under the specific proportion conditions of the present invention can the two main resins achieve a better silver powder alignment effect in the film and ensure the performance requirements such as impact resistance and water resistance. Secondly, the organosilicon-polyurethane-acrylate terpolymer emulsion adopted by the present invention is a terpolymer compound, which not only has the functions of ordinary acrylic emulsions, but also has the functions of organosilicon and polyurethane. Among them, the modified organosilicon can make the film have a better leveling effect, and the modified polyurethane provides better film performance.

[0018] In addition, the present invention also utilizes the high dispersibility characteristics of nano-barium sulfate for flaky pigments and fillers to improve the silver powder alignment effect, and its mechanism of action is as Figure 1 shown. Because barium sulfate belongs to an inert substance, compared with other traditional alignment aids (such as EVA wax, lithium magnesium silicate, etc.), barium sulfate hardly has post-reactions in the coating system, has extremely high stability, and avoids problems such as coating gelation and post-thickening caused by the instability of the alignment aids.

[0019] The present invention uses self-made nano-barium sulfate slurry and organosilicon-polyurethane-acrylate terpolymer emulsion to improve the alignment effect of waterborne silver powder paint, without the need to additionally add other silver powder alignment aids such as polyamide wax, EVA wax, lithium magnesium silicate, etc. At the same time, the storage stability of the paint liquid is improved, and the film can have a good silver powder alignment and flashing effect, making it have high stability, high brightness, and high fineness at the same time, and can meet the basic performance of automotive original factory paint films.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a high-brightness and high-fineness waterborne automotive aluminum paint, which can enable the paint film to simultaneously have the effects of high stability, high brightness and high fineness, meeting the basic performance requirements of the original automotive paint film.

[0021] Meanwhile, the preparation method of the high-brightness and high-fineness waterborne automotive aluminum paint provided by the present invention, compared with the prior art, does not require additional addition of other aluminum powder arrangement aids such as polyamide wax, EVA wax, lithium magnesium silicate, etc., simplifies the production process, reduces the production cost, and is suitable for large-scale production.

[0022] Applying the high-brightness and high-fineness waterborne automotive aluminum paint provided by the present invention to the preparation of automotive coatings or in the field of automotive coating application can significantly improve the construction performance and coating effect of the coatings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the mechanism of the ultrafine nano-barium sulfate slurry of the present invention to improve the arrangement of aluminum powder; Figure 2 is the measurement principle of the BYK mac i multi-angle color difference meter; Figure 3 is the relationship diagram between the G value and the fineness of the paint film; Figure 4 is the 100-fold microscope effect of Example 1; Figure 5 is the 100-fold microscope effect of Comparative Example 1; Figure 6 is the 100-fold microscope effect of Comparative Example 2; Figure 7 is the 100-fold microscope effect of Comparative Example 3; Figure 8 is the 100-fold microscope effect of Comparative Example 4; Figure 9 is the 100-fold microscope effect of Comparative Example 5; Figure 10 is the 100-fold microscope effect of Comparative Example 6. DETAILED DESCRIPTION OF THE INVENTION

[0024] The above content of the present invention will be further described in detail below through specific embodiments in the form of examples. However, it should not be understood that the scope of the above subject matter of the present invention is limited to the following examples.

[0025] 1. Raw materials Table 1 Sources of Formulation Raw Materials

[0026] 2. Equipment and Instruments The multi-angle color difference meter is purchased from BYK Company, Germany, model BYK mac i; The horizontal sand mill was purchased from NETZSCH Geratebau GmbH, Germany, with the model LMZ-05C.

[0027] Example 1 Preparation of the high-brightness and high-fineness waterborne automotive aluminum paint and its preparation method of the present invention The preparation of the ultrafine nano barium sulfate slurry of the present invention comprises the components shown in the following table: Table 2 Components of the ultrafine nano barium sulfate slurry

[0028] The preparation method of the ultrafine nano barium sulfate slurry of the present invention comprises: (1) Sequentially put the formulated amount of deionized water and dispersant B into the stirring tank. After dispersing for 10 minutes at 400 revolutions per minute, then put the formulated amount of nano barium sulfate. After dispersing for more than 30 minutes at 600 revolutions per minute; (2) Transfer all the liquid materials obtained in step (1) to a horizontal sand mill, and put in high-purity zirconia ceramic microbeads. The mass ratio of the high-purity zirconia ceramic microbeads to the liquid materials obtained in step (1) is 1.2:1. Grind for 2 h at 3000 revolutions per minute. When the fineness of the liquid materials is detected to be <5 μm, continue to grind for more than 30 minutes and then discharge to obtain the ultrafine nano barium sulfate slurry. The horizontal sand mill is NETZSCH LMZ-05C of Germany; the particle size of the high-purity zirconia ceramic microbeads is 0.3 mm.

[0029] The preparation of the high-brightness and high-fineness waterborne automotive aluminum paint of the present invention comprises the raw materials shown in the following table: Table 3 Raw materials of the high-brightness and high-fineness waterborne automotive aluminum paint of the present invention

[0030] The preparation method of the high-brightness and high-fineness waterborne automotive aluminum paint of the present invention comprises the following steps: (1) Take main cylinder A, and sequentially put the formulated amount of deionized water, N,N-dimethylethanolamine, acrylic acid-modified polyurethane dispersion, silicone-polyurethane-acrylate terpolymer emulsion and amino resin. Disperse for 15 minutes at 400 revolutions per minute; (2) Sequentially put the formulated amount of propylene glycol monobutyl ether, acetylenic diol surfactant and defoamer into main cylinder A in step (1). Disperse for 10 minutes at 500 revolutions per minute; (3) Put the formulated amount of ultrafine nano barium sulfate slurry into main cylinder A in step (2). Disperse for 10 minutes at 500 revolutions per minute; (4) Take another auxiliary cylinder B, and sequentially add the formulated amounts of silica-coated aluminum silver paste, ethylene glycol monobutyl ether, and 2-ethylhexyl glycol ether. After soaking for 2 hours, stir for 30 minutes. Ensure that there are no lumps or agglomerations, then sequentially add the formulated amounts of dispersant A and leveling agent, and stir for 30 minutes. Ensure that there are no lumps or agglomerations, and while stirring, pour auxiliary cylinder B into the main cylinder A in step (3). Disperse at 500 revolutions per minute for 15 minutes; (5) Add the formulated amount of thickener to the main cylinder A in step (4), and disperse at 600 revolutions per minute for 30 minutes; (6) While dispersing, adjust the pH with N,N-dimethylethanolamine to make the pH value within the range of 8.0 - 9.0; (7) After the pH value adjustment is completed, keep dispersing at 500 revolutions per minute for 10 minutes to obtain the high-brightness and high-smoothness waterborne automotive silver paint.

[0031] Example 2 Preparation of the high-brightness and high-smoothness waterborne automotive silver paint of the present invention The preparation of the ultrafine nano barium sulfate slurry of the present invention includes the components shown in the following table: Table 4 Components of the ultrafine nano barium sulfate slurry

[0032] The preparation method of the ultrafine nano barium sulfate slurry of the present invention includes: (1) Sequentially add the formulated amounts of deionized water and dispersant B to the stirring cylinder. After dispersing at 300 revolutions per minute for 15 minutes, then add the formulated amount of nano barium sulfate, and disperse at 500 revolutions per minute for more than 30 minutes; (2) Transfer all the liquid materials obtained in step (1) to a horizontal sand mill, and add high-purity zirconia ceramic microspheres. The mass ratio of the high-purity zirconia ceramic microspheres to the liquid materials obtained in step (1) is 1:1. Grind at 3000 revolutions per minute for 2.5 h. When the fineness of the liquid material is detected to be <5 μm, continue to grind for more than 30 minutes and then discharge to obtain the ultrafine nano barium sulfate slurry. The horizontal sand mill is Netzsch LMZ-05C of Germany; the particle size of the high-purity zirconia ceramic microspheres is 0.4 mm.

[0033] The preparation of the high-brightness and high-smoothness waterborne automotive silver paint of the present invention includes the raw materials shown in the following table: Table 5 Raw materials of the high-brightness and high-smoothness waterborne automotive silver paint of the present invention

[0034] The preparation method of the high-brightness and high-smoothness waterborne automotive silver paint of the present invention includes the following steps: (1) Take the main cylinder A, and sequentially add the formulated amounts of deionized water, N,N-dimethylethanolamine, acrylic-modified polyurethane dispersion, silicone-polyurethane-acrylate terpolymer emulsion, and amino resin. Disperse for 20 minutes at 300 revolutions per minute. (2) Sequentially add the formulated amounts of propylene glycol monobutyl ether, alkynediol surfactant, and defoamer to the main cylinder A in step (1). Disperse for 15 minutes at 300 revolutions per minute. (3) Add the formulated amount of ultrafine nano-barium sulfate slurry to the main cylinder A in step (2). Disperse for 15 minutes at 300 revolutions per minute. (4) Take another auxiliary cylinder B, and sequentially add the formulated amounts of silica-coated aluminum silver paste, ethylene glycol monobutyl ether, and ethylene glycol isooctyl ether. After soaking for 1 hour, stir for 35 minutes. Ensure no caking or agglomeration, then sequentially add the formulated amounts of dispersant A and leveling agent, and stir for 35 minutes. Ensure no caking or agglomeration, and then while stirring, put the auxiliary cylinder B into the main cylinder A in step (3). Disperse for 20 minutes at 300 revolutions per minute. (5) Add the formulated amount of thickener to the main cylinder A in step (4). Disperse for 35 minutes at 500 revolutions per minute. (6) While dispersing, adjust the pH with N,N-dimethylethanolamine to make the pH value within the range of 8.0 - 9.0. (7) After the pH value adjustment is completed, keep dispersing at 300 revolutions per minute for 15 minutes to obtain the high-brightness and high-fineness waterborne automotive silver paint.

[0035] Example 3 Preparation of the high-brightness and high-fineness waterborne automotive silver paint of the present invention The preparation of the ultrafine nano-barium sulfate slurry of the present invention includes the following components shown in the table: Table 6 Components of the ultrafine nano-barium sulfate slurry

[0036] The preparation method of the ultrafine nano-barium sulfate slurry of the present invention includes: (1) Sequentially add the formulated amounts of deionized water and dispersant B to the stirring cylinder. After dispersing for 5 minutes at 600 revolutions per minute, then add the formulated amount of nano-barium sulfate and disperse for more than 30 minutes at 700 revolutions per minute. (2) Transfer all the liquid materials obtained in step (1) to a horizontal sand mill, and add high-purity zirconia ceramic microspheres. The mass ratio of the high-purity zirconia ceramic microspheres to the liquid materials obtained in step (1) is 1.5:1. Grind at 3000 revolutions per minute for 1.5 h. When the fineness of the liquid material is detected to be <5 μm, continue to grind for more than 30 minutes and then discharge to obtain the ultrafine nano-barium sulfate slurry. The horizontal sand mill is Netzsch LMZ-05C of Germany; the particle size of the high-purity zirconia ceramic microspheres is 0.5 mm.

[0037] The preparation of the high-brightness and high-fineness waterborne automotive silver powder paint of the present invention includes the raw materials shown in the following table: Table 7 Raw materials of the high-brightness and high-fineness waterborne automotive silver powder paint of the present invention

[0038] The preparation method of the high-brightness and high-fineness waterborne automotive silver powder paint of the present invention includes the following steps: (1) Take the main cylinder A, and successively add the formulated amounts of deionized water, N,N-dimethylethanolamine, acrylic acid-modified polyurethane dispersion, silicone-polyurethane-acrylate terpolymer emulsion and amino resin, and disperse for 15 minutes under the condition of 600 revolutions per minute; (2) Successively add the formulated amounts of propylene glycol monobutyl ether, acetylenic diol surfactant and defoamer to the main cylinder A in step (1), and disperse for 5 minutes under the condition of 600 revolutions per minute; (3) Add the formulated amount of ultrafine nano-barium sulfate slurry to the main cylinder A in step (2), and disperse for 5 minutes under the condition of 600 revolutions per minute; (4) Take another auxiliary cylinder B, and successively add the formulated amounts of silica-coated aluminum silver paste, ethylene glycol monobutyl ether and ethylene glycol isooctyl ether. After soaking for 3 hours, stir for 25 minutes to ensure no caking or agglomeration. Then, successively add the formulated amounts of dispersant A and leveling agent, and stir for 25 minutes to ensure no caking or agglomeration. While stirring, put the auxiliary cylinder B into the main cylinder A in step (3), and disperse for 15 minutes under the condition of 600 revolutions per minute; (5) Add the formulated amount of thickener to the main cylinder A in step (4), and disperse for 25 minutes at 800 revolutions per minute; (6) While dispersing, adjust the pH with N,N-dimethylethanolamine to make the pH value within the range of 8.0 - 9.0; (7) After the pH value adjustment is completed, keep dispersing at 600 revolutions per minute for 10 minutes to obtain the high-brightness and high-fineness waterborne automotive silver powder paint.

[0039] Example 4 The high-brightness and high-fineness waterborne automotive silver powder paint of the present invention and its preparation The preparation of the ultrafine nano-barium sulfate slurry of the present invention includes the components shown in the following table: Table 8 Components of the ultrafine nano-barium sulfate slurry

[0040] The preparation method of the ultrafine nano-barium sulfate slurry of the present invention includes: (1) Successively add the formulated amounts of deionized water and dispersant B to the stirring cylinder, disperse for 10 minutes under the condition of 500 revolutions per minute, and then add the formulated amount of nano-barium sulfate, and disperse for more than 30 minutes under the condition of 600 revolutions per minute; (2) Transfer all the feed liquid obtained in step (1) to a horizontal sand mill, and add high-purity zirconia ceramic beads. The mass ratio of the high-purity zirconia ceramic beads to the feed liquid obtained in step (1) is 1.3:1. Grind for 2 h under the condition of 3000 revolutions per minute. When the fineness of the feed liquid is detected to be <5 μm, continue to grind for more than 30 min and then discharge the material to obtain the ultrafine nano barium sulfate slurry. The horizontal sand mill is Netzsch LMZ-05C from Germany; the particle size of the high-purity zirconia ceramic beads is 0.6 mm.

[0041] The preparation of the high-brightness and high-fineness waterborne automotive silver powder paint of the present invention comprises the raw materials as shown in the following table: Table 9 Raw Materials of the High-Brightness and High-Fineness Waterborne Automotive Silver Powder Paint of the Present Invention

[0042] The preparation method of the high-brightness and high-fineness waterborne automotive silver powder paint of the present invention comprises the following steps: (1) Take main cylinder A, and sequentially add the formulated amounts of deionized water, N,N-dimethylethanolamine, acrylic-modified polyurethane dispersion, silicone-polyurethane-acrylate terpolymer emulsion and amino resin, and disperse for 20 minutes under the condition of 400 revolutions per minute; (2) Sequentially add the formulated amounts of propylene glycol monobutyl ether, alkynediol surfactant and defoamer to main cylinder A in step (1), and disperse for 10 minutes under the condition of 500 revolutions per minute; (3) Add the formulated amount of ultrafine nano barium sulfate slurry to main cylinder A in step (2), and disperse for 10 minutes under the condition of 500 revolutions per minute; (4) Take another auxiliary cylinder B, sequentially add the formulated amounts of silica-coated aluminum silver paste, ethylene glycol monobutyl ether and ethylene glycol isooctyl ether, soak for 2 hours, stir for 30 minutes, ensure no caking and no agglomeration, then sequentially add the formulated amounts of dispersant A and leveling agent, stir for 30 minutes, ensure no caking and no agglomeration, and while stirring, put auxiliary cylinder B into main cylinder A in step (3), and disperse for 20 minutes under the condition of 500 revolutions per minute; (5) Add the formulated amount of thickener to main cylinder A in step (4), and disperse for 30 minutes at 700 revolutions per minute; (6) While dispersing, adjust the pH with N,N-dimethylethanolamine to make the pH value in the range of 8.0-9.0; (7) After the pH value is adjusted, keep dispersing for 10 minutes at 500 revolutions per minute to obtain the high-brightness and high-fineness waterborne automotive silver powder paint.

[0043] Comparative Example 1 Compared with Example 1, the addition amount of the acrylic acid-modified polyurethane dispersion in this example is 8 parts, and the addition amount of the silicone-polyurethane-acrylate terpolymer emulsion is 31 parts. Other conditions are the same as those in Example 1.

[0044] The preparation method described in Example 1 was adopted to prepare the aqueous automotive silver paint.

[0045] Comparative Example 2 Compared with Example 1, the addition amount of the acrylic acid-modified polyurethane dispersion in this example is 20 parts, and the addition amount of the silicone-polyurethane-acrylate terpolymer emulsion is 19 parts. Other conditions are the same as those in Example 1.

[0046] The preparation method described in Example 1 was adopted to prepare the aqueous automotive silver paint.

[0047] Comparative Example 3 Compared with Example 1, in this example, the ultrafine nano-barium sulfate slurry was replaced with the EVA wax type silver powder orientation aid BYK AQUACER 526. Other conditions are the same as those in Example 1.

[0048] The preparation method described in Example 1 was adopted to prepare the aqueous automotive silver paint.

[0049] Comparative Example 4 Compared with Example 1, in this example, the ultrafine nano-barium sulfate slurry was replaced with the polyamide wax silver powder orientation aid Disparlon AQH-810. Other conditions are the same as those in Example 1.

[0050] The preparation method described in Example 1 was adopted to prepare the aqueous automotive silver paint.

[0051] Comparative Example 5 Compared with Example 1, in the preparation method of the high-brightness and high-fineness aqueous automotive silver paint in this example, in step (6), N,N-dimethylethanolamine was used to adjust the pH to 7.5. Other conditions are the same as those in Example 1.

[0052] Comparative Example 6 Compared with Example 1, in the preparation method of the high-brightness and high-fineness aqueous automotive silver paint in this example, in step (6), N,N-dimethylethanolamine was used to adjust the pH to 9.5. Other conditions are the same as those in Example 1.

[0053] Experiment 1 The aqueous automotive silver paints prepared in Examples 1-4 and Comparative Examples 1-6 of the present invention were subjected to performance tests. The test methods and test results are shown in Tables 10, 11, 12 and 13.

[0054] (1) Detection items and test methods Table 10

[0055] The names of the relevant standards are as follows: GB / T 9754 "Paints and varnishes - Determination of specular gloss at 20°, 60° and 85° of non - metallic - pigmented paint films"; GB / T 9286 "Paints and varnishes - Cross - cut test"; GB / T 6739 "Paints and varnishes - Determination of film hardness by pencil test"; GB / T 1732 "Method for the determination of impact resistance of film"; GB / T 9753 "Paints and varnishes - Conical mandrel test"; GB / T 1733 "Method for the determination of water resistance of film"; GB / T 9274 "Paints and varnishes - Determination of resistance to liquid media"; GB / T 1740 "Method for the determination of resistance to damp heat of film"; GB / T 6753.3 "Test methods for storage stability of paints"; GB / T 1865 "Paints and varnishes - Artificial weathering and exposure to artificial radiation - Filtered xenon - arc radiation".

[0056] Description of the test items: For the lightness, aluminum powder arrangement effect and fineness of the paint film, in addition to direct visual assessment, data - based measurement and assessment can usually be carried out using the BYKmac i multi - angle color difference meter. Among them: L value: It reflects the brightness of the paint film. The BYK mac i can directly measure the L values at different viewing angles (15°, 25°, 45°, 75° and 110°). Its measurement principle is as Figure 2 shown. The larger the L value, the brighter the paint film.

[0057] FI value: It reflects the metamerism of lightness (L value). Its specific calculation formula: FI = 2.69×(L 15° -L 110° ) 1.11 / L 45° 0.86 The FI value indicates the change in the brightness of the paint film when observed from different angles. Generally, for silver paint with good metal orientation, the specular reflection generated by parallel light hitting the paint film is strong. The brightness is high at small angles (15°, 25°) and low at large angles (45°, 75°, 110°), and the FI value will be relatively large. Conversely, if the metal arrangement in the paint film is poor and the silver flakes "stand up" instead of "lying flat", it will lead to strong light scattering, lower brightness at small angles, and higher brightness at large angles, resulting in a smaller FI value. Therefore, the size of the FI value is an important criterion for evaluating the quality of the aluminum silver flake orientation in the paint film.

[0058] G value: It reflects the gritty effect of the paint film and indicates whether the paint film is rough or delicate. It is usually specified that the G value of a very uniform solid-color paint = 0. The smaller the G value, the more obvious the delicate feeling of the paint film. The relationship diagram between the G value and the paint film fineness is shown below Figure 3 as follows.

[0059] If only high fineness is pursued, using medium or relatively fine particle size aluminum silver paste can relatively easily make the G value small, but at the same time, the brightness L value of the paint film will be relatively small, and the visual metal effect will be relatively poor. Therefore, the paint formulation needs to have relatively good silver powder orientation to enhance the "laying flat" of the silver flakes in order to make the paint film have both high fineness and high brightness.

[0060] (2)Test Results Table 11 Test Results of High-Brightness and High-Delicacy Waterborne Automotive Silver Paint in Examples 1 - 4 of the Present Invention

[0061] Table 12 Test Results of Waterborne Automotive Silver Paint in Comparative Examples 1 - 6

[0062] Table 13 Measurement Results of BYK-mac i Multi-Angle Color Difference Meter

[0063] (3)Analysis of Experimental Results Compared with Example 1, in Comparative Example 1 and Comparative Example 2, the mass ratio of the acrylic-modified polyurethane dispersion and the silicone-polyurethane-acrylate terpolymer emulsion was adjusted. In Comparative Example 3 and Comparative Example 4, the ultrafine nano-barium sulfate slurry was replaced with a commercially available silver powder orientation aid. In Comparative Example 5 and Comparative Example 6, the reaction pH was adjusted. Combining the experimental results such as paint performance tests and color difference meter data, it can be seen that: The change in the mass ratio of the acrylic-modified polyurethane dispersion and the silicone-polyurethane-acrylate terpolymer emulsion affects the FI value, G value, water resistance, cupping test, and impact resistance of the automotive paint film, making it fail to meet the performance requirements of the automotive paint film. Using a commercially available silver powder orientation aid has little effect on the paint film properties such as water resistance, but the L value and FI value are on the low side, indicating that the silver powder arrangement effect is slightly worse than that of the ultrafine nano-barium sulfate slurry of the present invention. Moreover, after storing at 40 °C for 30 days, the paint thickens moderately, indicating that its storage stability is even worse. Adjusting the pH value ≤ 7.5 results in incomplete resin swelling and a decrease in the lightness of the paint film; adjusting the pH value ≥ 9.5 leads to excessive resin swelling, poor storage stability, and a significant viscosity reduction, indicating that a pH value in the range of 8.0 - 9.0 is more suitable.

[0064] Experiment Two To further observe the arrangement effect of the waterborne automotive silver powder paint of the present invention, the waterborne automotive silver powder paints prepared in Example 1 and Comparative Examples 1 - 6 were observed under a 100-fold microscope. The microscope was purchased from LEICA Company in Germany, and its model is DM2700M.

[0065] The experimental results are as Figures 4 to 10 shown. It can be seen from the experimental results that the silver powder of the waterborne automotive silver powder paint prepared in Example 1 of the present invention is closely arranged, and the blackening area is very small. The directional arrangement effect of its silver powder is significantly better than that of Comparative Examples 2 - 5.

[0066] In summary, the present invention combines the acrylic-modified polyurethane dispersion with the silicone-polyurethane-acrylate terpolymer emulsion, and at the same time adds nano-barium sulfate slurry to assist the directional arrangement of silver powder, which can achieve a high FI value (FI > 15), a high L value (L15° > 140), and a low G value (G < 4.5). Moreover, after storing the paint at 40 °C for 30 days, there is no abnormality, and the paint film performance is normal, indicating that the present invention meets the requirements of high brightness, high fineness, and high stability at the same time; and the ratio of the acrylic-modified polyurethane dispersion to the silicone-polyurethane-acrylate terpolymer emulsion is appropriate, ensuring that the paint film has excellent properties, such as water resistance, heat and humidity resistance for more than 10 days, the cross-cut adhesion test is grade 0, and there are no abnormal paint film phenomena such as obvious color change; the paint film has good flexibility, and the test results of impact resistance and cupping resistance are higher than the paint film index requirements of most original automotive paints.

[0067] The above embodiments are only illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A high-brightness and high-fineness water-based automotive silver paint, characterized in that: In terms of weight percentage, the following raw materials are included: 12-18 parts of acrylic acid modified polyurethane dispersion, 20-30 parts of silicone-polyurethane-acrylate ternary copolymer emulsion, 2-5 parts of amino resin, 0.5-1.5 parts of acetylene glycol surfactant, 0.5-2 parts of thickener, 2-5 parts of ultrafine nano barium sulfate slurry, 4-6 parts of silica-coated aluminum silver paste, 0.1-1 parts of dispersant A, 0.05-0.5 parts of leveling agent, 0.1-1 parts of defoaming agent, 0.5-2 parts of N,N-dimethylethanolamine, 5-10 parts of ethylene glycol butyl ether, 1-5 parts of propylene glycol butyl ether, 1-5 parts of ethylene glycol isooctyl ether and 20-40 parts of deionized water.

2. The high-brightness and high-fineness water-based automotive silver paint according to claim 1, characterized in that: The mass ratio of the acrylic acid-modified polyurethane dispersion to the silicone-polyurethane-acrylate ternary copolymer emulsion is 1:(1.3-2.8).

3. The high-brightness and high-fineness water-based automotive silver paint according to claim 1, characterized in that: The acrylic modified polyurethane dispersion is at least one of DAOTAN TW6466 / 36WA, DAOTAN TW6462 / 36WA and DAOTAN TW6464 / 36WA of allnex; the silicone-polyurethane-acrylate ternary copolymer emulsion is Dolphin 1830 of Dolphin New Materials; the amino resin is at least one of CYMEL 325 and CYMEL 327 of allnex; the acetylene glycol surfactant is at least one of Surfynol 440, Surfynol 420 and Surfynol 104 DPM of Evonik; and the thickener is at least one of Viscalex HV 30 and RHEOVIS AS 1130 of BASF.

4. The high-brightness and high-fineness water-based automotive silver paint according to claim 1, characterized in that: In terms of weight percentage, the ultrafine nano-barium sulfate slurry includes the following components: 30-50 parts of nano-barium sulfate, 10-30 parts of dispersant B and 20-40 parts of deionized water.

5. The high-brightness and high-fineness water-based automotive silver paint according to claim 4, characterized in that: The dispersant B is at least one of BYK-192 and BYK-190; the nano barium sulfate is at least one of Sakai Chemical BARIFINE BF-20 and Hongzhi New Material FB-30.

6. The high-brightness and high-fineness water-based automotive silver paint according to claim 5, characterized in that: The method for preparing the ultrafine nano barium sulfate slurry comprises: (1) Add the formulated amount of deionized water and dispersant B into the mixing tank in sequence, disperse for 5 to 15 minutes at 300 to 600 rpm, then add the formulated amount of nano-barium sulfate, and disperse for more than 30 minutes at 500 to 700 rpm; (2) Transfer all the liquid obtained in step (1) to a horizontal sand mill, add high-purity zirconium oxide ceramic microbeads, and the mass ratio of the high-purity zirconium oxide ceramic microbeads to the liquid obtained in step (1) is (1-1.5):1, sand mill at 2500-3500 rpm for 1.5-2.5 h. When the fineness of the liquid is less than 5 μm, continue sand milling for more than 30 min, then discharge the material to obtain ultrafine nano barium sulfate slurry.

7. The high-brightness and high-fineness water-based automotive silver paint according to claim 6, characterized in that: The horizontal sand mill is produced by NETZSCH Instrument Manufacturing Co., Ltd. of Germany, model LMZ-05C; the particle size of the high-purity zirconia ceramic microbeads is 0.3-0.6 mm.

8. The high-brightness and high-fineness water-based automotive silver paint according to claim 1, characterized in that: The silica-coated aluminum paste is Anhui Xuyang 3016A water-based aluminum paste; the dispersant A is at least one of BYK-192 and BYK-190; the leveling agent is at least one of BYK-381, BYK-345 and BYK-347; the defoaming agent is at least one of TEGO 810, Airex 902W and BYK-011.

9. The method for preparing the high-brightness and high-fineness water-based automotive silver paint according to any one of claims 1 to 8, characterized in that: The steps include: (1) Take the main cylinder A, add the formulated amount of deionized water, N,N-dimethylethanolamine, acrylic acid-modified polyurethane dispersion, silicone-polyurethane-acrylate ternary copolymer emulsion and amino resin in sequence, and disperse for 15-20 minutes at 300-600 rpm; (2) Adding the formulated amounts of propylene glycol butyl ether, acetylene glycol surfactant and defoamer into the main cylinder A in step (1) in sequence, and dispersing for 5 to 15 minutes at 300 to 600 rpm; (3) Add the formulated amount of ultrafine nano barium sulfate slurry into the main cylinder A in step (2) and disperse it for 5 to 15 minutes at 300 to 600 rpm; (4) Take another auxiliary cylinder B, add the formulated amount of silica-coated aluminum silver paste, ethylene glycol butyl ether and ethylene glycol isooctyl ether in sequence, soak for 1 to 3 hours, stir for 25 to 35 minutes to ensure that there is no agglomeration, then add the formulated amount of dispersant A and leveling agent in sequence, stir for 25 to 35 minutes to ensure that there is no agglomeration, and then add the auxiliary cylinder B into the main cylinder A of step (3) while stirring, and disperse for 15 to 20 minutes at 300 to 600 rpm; (5) Add the formulated amount of thickener into the main cylinder A in step (4) and disperse at 500-800 rpm for 25-35 minutes; (6) While dispersing, adjust the pH using N,N-dimethylethanolamine to a pH value within the range of 8.0 to 9.0; (7) After the pH value is adjusted, maintain the speed at 300-600 rpm and disperse for 10-15 minutes to obtain a high-brightness and high-fineness water-based automotive silver paint.

10. Use of the high-brightness and high-fineness water-based automobile silver powder paint according to any one of claims 1 to 9 in the preparation of automobile coatings or in the field of automobile coatings.

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