Water-based color paint having high wettability on sealant and use thereof

Abstract

The application discloses a water-based color paint with high wettability on sealant and application thereof. The water-based color paint comprises, in parts by weight, 20-25 parts of acrylic resin, 0.3-1.0 parts of phosphoric acid modified acrylic resin, 3-10 parts of amino resin, 3-5 parts of polyurethane resin, 3-5 parts of polyester resin, 2-8 parts of pigment, 2-8 parts of functional filler paste, 3-12 parts of auxiliary agent, 5-10 parts of organic solvent and 30-50 parts of water, wherein the functional filler paste is a semi-finished product obtained by pre-mixing superfine nano barium sulfate, acrylic resin B and water. By adding the functional filler paste containing the superfine nano barium sulfate in the water-based color paint formula, the wettability problem of the water-based color paint on the sealant for automobiles, especially the wettability problem of the sealant at a brush mark, can be effectively solved, and meanwhile, the requirements on the paint film performance such as the paint film adhesion and appearance in application can be met.

Description

Technical Field

[0001] This invention relates to the field of water-based paint technology. More specifically, it relates to a water-based paint with high wetting properties on sealants and its application. Background Technology

[0002] A car body is primarily assembled from sturdy steel sheets stamped into various components. These components are then joined together using sophisticated welding techniques to form a complete car body. Take a car door as an example: it is actually connected by spot welding two layers of steel sheets. This design achieves functions such as machinability, lightweight structure, heat insulation, and sound insulation. Upon closer inspection, it can be seen that spot welding leaves gaps at the joints. Imagine if these gaps weren't addressed; they would not only affect the car's aesthetics but could also allow dust and water to enter the body, corroding the interior. Currently, car manufacturers address these gaps by using polyvinyl chloride (PVC) sealant. When applying the sealant, in addition to filling the gaps, aesthetics are also considered. Modern machines are used to apply the sealant, typically in thin rectangular or semi-cylindrical shapes. Then, a brush is used to carefully smooth the edges, and after curing, the sealant proceeds to the next painting step.

[0003] With the gradual development of environmental awareness, most paint systems have been updated to water-based paint systems, gradually replacing solvent-based paints. However, due to the high surface tension of water, wetting problems on sealants, which were almost non-existent when using solvent-based paints, frequently occur when using water-based paints. These problems vary depending on the paint color, the sealant manufacturer, and even batch variations. For example, numerous pinholes may appear on the sealant, especially at the edges of brush-treated sealants. The common solution to pinhole problems is to add appropriate emulsifiers and surface conditioning agents (such as leveling agents and wetting / dispersing agents) and adjust the proportions to resolve the wetting issue. However, this is not a universal solution. Adding extra emulsifiers and surface conditioning agents to some paint systems may introduce new film problems. For example, the addition of emulsifiers, due to their partial hydrophilicity, can easily lead to a decrease in film performance such as adhesion and water resistance; while surface conditioning agents can reduce the surface tension of the paint, they can easily cause problems with film adhesion and a decline in appearance.

[0004] Therefore, it is necessary to develop a water-based automotive paint that has good wetting properties on sealants and whose film properties, such as adhesion and appearance, meet application requirements. Summary of the Invention

[0005] One object of the present invention is to provide a water-based paint with high wettability on sealants.

[0006] Another object of the present invention is to provide an application of the water-based paint described above in automotive body painting.

[0007] To achieve the first objective mentioned above, the present invention adopts the following technical solution:

[0008] This invention discloses a water-based paint with high wetting properties on sealants, wherein, by weight, the water-based paint comprises...

[0009] 20-25 parts acrylic resin;

[0010] 0.3-1.0 parts of phosphoric acid modified acrylic resin;

[0011] 3-10 parts of amino resin;

[0012] 3-5 parts of polyurethane resin;

[0013] 3-5 parts of polyester resin;

[0014] 2-8 parts pigment;

[0015] 2-8 parts of functional filler slurry;

[0016] 3-12 parts of auxiliary agent;

[0017] 5-10 parts organic solvent;

[0018] 30-50 parts water;

[0019] The acrylic resin comprises acrylic resin A with a Tg value of 21-31℃ and a particle size of 80-160nm, and acrylic resin B with a Tg value of 7-17℃ and a particle size of 40-80nm.

[0020] The functional filler slurry is a semi-finished product obtained by pre-mixing ultrafine nano barium sulfate, acrylic resin B, and water.

[0021] Furthermore, the mass ratio of acrylic resin A to acrylic resin B is 2-4:1.

[0022] Furthermore, the acrylic resin A is selected from one or more of DIC's EMA-1015, EMA-1032, and Wanhua Chemical's ACKETONE2033, and the acrylic resin B is selected from one or more of DIC's EMA-1036, ACW-1011, and Wanhua Chemical's ACKETONE2025.

[0023] Furthermore, the ultrafine nano-barium sulfate is selected from BARIFINE BF-21 and / or BARIFINE BF-25, with an average particle size of 0.03-0.05 μm.

[0024] Furthermore, the weight percentage of the ultrafine nano barium sulfate in the water-based paint is 0.3-5%, more preferably 0.5-2%.

[0025] Furthermore, the functional filler slurry is prepared according to the following steps:

[0026] Mix 25-35 parts by weight of acrylic resin B and 45-55 parts by weight of water evenly, add 18-22 parts by weight of ultrafine nano barium sulfate while stirring, stir at 400-600 rpm for 30 minutes, and then grind until the fineness is ≤5μm to obtain the product.

[0027] Furthermore, the acid value of the phosphoric acid modified acrylic resin is 160-220 mg KOH / g.

[0028] Furthermore, the phosphoric acid modified acrylic resin is selected from one or more of NAC's ACS-1016, ACS-1212, and Lubrizol's lubrizol2062.

[0029] Furthermore, the amino resin comprises amino resin A with a number average molecular weight of 600-700, a weight average molecular weight of 900-1200, and an imino content of 1.5-2.0%, and amino resin B with a number average molecular weight of 1000-1200, a weight average molecular weight of 2000-3000, and an imino content of 0.5-1.0%.

[0030] Furthermore, the mass ratio of amino resin A to amino resin B is 5-9:1.

[0031] Furthermore, the amino resin A is selected from one or more of Zhanxin's CYMEL 202, CYMEL 370, and CYMEL 254;

[0032] The amino resin B is selected from Mitsui Chemicals' UVAN60SE and / or Zenshin's CYMEL 250.

[0033] Furthermore, the polyurethane resin is selected from NAC's N2-4000 and / or DSM's NEOREZ R-9603;

[0034] The polyester resin is selected from one or more of DIC's PRS-1045, NP-6100, and NP-5000.

[0035] Furthermore, the pigment contains 0.1-5 parts of aluminum powder, wherein the aluminum powder is selected from one or more of 4660NS, 4640NS, MH-8801, and 7640NS.

[0036] Furthermore, the pigment also includes one or more of HOSTAPERM VIOLET RL, EMPEROR 2000 carbon black, PaliotolGelb L 2140HD, SICOTRANS YELLOW L1916, IRGAZIN Yellow 5GLT, and SR1C.

[0037] Furthermore, the adjuvant contains 0.1-2 parts of a rheology modifier, wherein the rheology modifier is selected from one or more of BASF's RHEOVISAS1130, ADEKA's ADEKANOL UH-814N, BYK Chemical's BYK-465, and AQUTIX-8461;

[0038] The additives also include at least one of a light stabilizer, a wetting and dispersing agent, and an emulsifier, in a total mass fraction of 1-5 parts.

[0039] To achieve the second objective mentioned above, the present invention adopts the following technical solution:

[0040] This invention discloses the application of water-based paint as described above in automobile body painting.

[0041] The beneficial effects of this invention are as follows:

[0042] This invention adds a functional filler slurry containing ultrafine nano-barium sulfate to the water-based paint formulation, thereby increasing the surface tension of the water-based paint and thus giving it higher surface energy. This allows the paint droplets to flow faster after being applied to the sealant surface, enabling them to fill brush marks. Compared to traditional methods of adding emulsifiers and surface conditioning additives, this invention has the following advantages:

[0043] 1) It can eliminate coating adhesion problems and appearance degradation caused by emulsifiers and surface modifiers because the functional filler paste containing ultrafine nano barium sulfate has little impact on adhesion and appearance.

[0044] 2) Since the paint film is usually thinner in the sealant area, it dries faster, so the initial flow rate is more important. After adding functional filler paste, the initial flow rate of the paint of the present invention is faster and more suitable for body painting containing sealant.

[0045] 3) The ultrafine nano barium sulfate in the functional filler slurry can replace some organic pigments and form thickening associations with polyurethane, resulting in a decrease in the thixotropy of the paint. This is beneficial for producing smaller particles during electrostatic rotary cup atomization, which is more conducive to filling the brush marks of sealant.

[0046] 4) Ultrafine nano barium sulfate helps to increase the specific gravity of paint droplets, making it easier for paint droplets to flow into the sealant brush marks;

[0047] 5) Ultrafine nano barium sulfate is easier to wet with the raw materials in the sealant, thereby improving the wettability of water-based paint on the sealant.

[0048] 6) Under the combined action of acrylic resin, amino resin, phosphate-modified acrylic resin, polyurethane resin, polyester resin, functional filler paste and additives, the resulting water-based paint has a non-volatile content of 20-25%, a viscosity of 60-70S (FORD-4# cup 25℃), and VOC ≤ 420g / L, which fully meets the requirements of GB / T38597-2020 "Technical Requirements for Coatings with Low Volatile Organic Compound Content". The appearance, adhesion and various resistance properties of the paint film all meet the standards.

[0049] Therefore, the water-based paint for automobiles provided by this invention is suitable for painting automobile bodies, and is particularly beneficial for improving pinholes in areas with sealant brush marks. Attached Figure Description

[0050] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0051] Figure 1 The images show before and after photos of problematic paint being sprayed onto a rectangular sealant surface that was not treated with a brush. Figure 1 Image a is a magnified photo taken 100 times before spraying. Figure 1 Photo b in the middle is the photo after spraying.

[0052] Figure 2 The images show before and after the problematic paint was sprayed onto a rectangular sealant surface that had undergone simulated brush treatment. Figure 2 Image a is a magnified photo taken 100 times before spraying. Figure 2 Photo b in the middle is the photo after spraying. Detailed Implementation

[0053] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further explains the invention. Similar components in the drawings are indicated by the same reference numerals. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0054] Unless otherwise stated, the term "parts" in the embodiments of this invention has the same meaning as parts by weight.

[0055] The wettability of paint on a substrate depends primarily on the difference in surface tension between the two. Generally, the surface tension of the paint should be lower than that of the substrate to ensure good wettability and adhesion. Wetting performance can be measured by the contact angle between the liquid and the solid, and calculated using Young's equation.

[0056] Generally, the sealant used on car bodies is semi-cylindrical or cuboid in shape. After curing, its surface is uniform with a relatively consistent surface tension. However, areas where the sealant edges have been brushed create a unique micron-scale surface due to the fine brush marks, producing brush marks of 10-50 μm. These micron-sized brush marks create an air layer, preventing complete water wetting and resulting in a very low contact area between water and the sealant surface, forming a hydrophobic structure similar to the lotus leaf effect. Taking a cuboid sealant as an example, measurements of the water contact angle on the sealant surface show that the water contact angle on a cuboid sealant surface without brush marks is approximately 87-89°, with an average surface tension of approximately 39.9 mJ / m. 2 However, in areas with brush marks, the water contact angle is approximately 84-125°, and the average surface tension is approximately 35.6 mJ / m. 2 This means that the area with brush marks has a lower surface tension, forming a highly hydrophobic structure. Therefore, when spraying water-based paint onto sealant, especially on areas where the sealant edges have been brushed, water-based paint is more likely to cause sealant wetting problems compared to solvent-based paint because water has a surface tension of 60 mN / m, while most solvents have a surface tension of less than 30 mN / m.

[0057] To better illustrate the aforementioned issues, magnified photographs (100x magnification) of water-based paint with wetting problems (hereinafter referred to as problematic paint) applied to an untreated rectangular sealant surface are provided (see [link]). Figure 1 ) and 100x magnified photos of the problematic paint applied to a rectangular sealant surface before and after simulated brush treatment (see) Figure 2 ),Depend on Figure 1 and Figure 2 The comparison reveals that areas touched up with a brush after painting are more prone to the problem of water-based paint not wetting the sealant.

[0058] Considering that the above problems are caused by the wetting properties of water-based paints, the first step is to try using emulsifiers and surface conditioning agents (such as leveling agents and wetting and dispersing agents) to improve the wetting properties of water-based paints. The specific solutions are as follows:

[0059] Example 1: Increase the amount of emulsifier

[0060] Prepare water-based paints according to the formulation amounts in Table 1. See Table 4 for paint and coating film characteristics data.

[0061] Table 1 Example 1 Water-based paint formulation

[0062]

[0063]

[0064] This example provides a method for preparing water-based paints, the steps of which are as follows:

[0065] In the first container, acrylic resin EMA-1015 and acrylic resin ACW-1011 were added and stirred for 5 minutes. Then, emulsifier FS-640 was added, and amino resin CYMEL 254 and amino resin UVAN60SE were added while stirring. After stirring for 20 minutes, the pH value was adjusted to 8-8.5 with pH adjuster DMEA. Then, polyester resin NP-5000 and polyurethane resin NEOREZ R-9603 were added, and water was used to adjust the rotor viscosity B6 to 7000-10000 rpm to obtain a mixed resin solution.

[0066] In the second container, solvent isooctyl alcohol, ethylene glycol isooctyl ether and aluminum powder are added and soaked for 15 minutes. After stirring evenly, phosphoric acid modified acrylic resin ACS-1016 is added and stirred for 20 minutes. While stirring, emulsifier FS-640, wetting and dispersing agent BYK-192 and light stabilizer Tinuvin123 are added and stirred for 5 minutes to obtain aluminum powder dispersion.

[0067] Slowly pour the aluminum powder dispersion from the second container into the first container while stirring, and stir at 500-600 rpm for 20 minutes.

[0068] While stirring, add the color paste SR1C into the first container and stir for 5 minutes. Slowly add the rheology modifier ADEKANOLUH-814N and stir at 500-600 rpm for 15 minutes. While stirring, add pure water, the remaining leveling agent BYK-345, and the solvent SHELLSOL TK.

[0069] The pH value is adjusted using pH adjuster DMEA, and the viscosity and solids content are adjusted using water to obtain water-based paint.

[0070] Example 2: Increase the amount of leveling agent

[0071] The water-based paint was prepared according to the formulation amounts in Table 2. The preparation process is the same as in Example 1. The coating and film characteristics data are shown in Table 4.

[0072] Table 2 Example 2 Water-based paint formulation

[0073]

[0074]

[0075] Example 3: Increase the amount of wetting and dispersing agent

[0076] The water-based paint was prepared according to the formulation amounts in Table 3. The preparation process is the same as in Example 1. The paint and coating film characteristics data are shown in Table 4.

[0077] Table 3 Example 3 Water-based paint formulation

[0078]

[0079]

[0080] Performance Test 1

[0081] The prepared water-based paint was used to prepare a composite coating film. The preparation of the composite coating film was carried out in accordance with conventional methods in the field, and the application process is as follows:

[0082] ED board → partial application of sealant → baking at 135℃ for 25 minutes → water-based dark gray intermediate coat → baking at 140℃ for 20 minutes → water-based color paint → baking at 80℃ for 4 minutes → clear varnish → baking at 140℃ for 30 minutes.

[0083] The conventional sealant is made into a rectangle with dimensions of 75mm*20mm*(2-3)mm on the electrophoresis plate; the sealant used to simulate edge brush treatment is applied by lightly scraping a 75mm*20mm area onto the electrophoresis plate with the edge of a cut tinplate, resulting in a stringy surface (see...). Figure 2 ).

[0084] The film thicknesses of the above-mentioned intermediate coat, color paint, and clear coat are 10-15μm, 8-10μm, and 20-25μm, respectively.

[0085] Table 4. Coating and Coating Film Properties Data

[0086] Test Project Test methods Problem paint Example 1 Example 2 Example 3 Original paint viscosity (F-4# cup, 25℃, s) MS600-35 4.3 65 65 65 65 Solid content 110℃*1h MS600-35 4.3 22.6 22.6 22.6 22.6 VOC content (g / L) GB24409-2020 370 368 371 371 Specific gravity (g / cm3) 3 ​ MS600-35 4.2 1.0230 1.0230 1.0232 1.0231 Surface tension of the coating liquid (mN / m) Contact Angle Meter 22.7 22.3 22.6 22.7 Visual appearance of paint film MS600-35 6.1 OK NG OK OK FI index MS600-35 6.2 6.80 6.33 6.46 6.76 Adhesion MS600-35 6.8 Level 0 Level 3, NG Level 0 Level 0 Water resistance 40℃*10 days MS653-01 6.6 OK Adhesion NG Adhesion NG OK Wetting status of sealant brush marks Visual inspection NG NG OK NG

[0087] The above tests show that increasing the amount of emulsifier does not improve the wetting of the sealant brush marks, and it also causes problems with adhesion and water resistance.

[0088] Increasing the amount of silicone-based leveling agent can improve the wetting of the sealant brush marks and make it meet the requirements, but it will also reduce the water resistance and fail to meet the application needs.

[0089] Increasing the amount of wetting and dispersing agent does not reduce the appearance, color, adhesion, or other important properties of the coating film as measured in actual tests, but it does not solve the wetting problem on the sealant and instead increases the cost of raw materials.

[0090] To better address the aforementioned problems, this invention provides a water-based paint with high wetting properties on sealants, comprising, by weight, parts of...

[0091] 20-25 parts acrylic resin;

[0092] 0.3-1.0 parts of phosphoric acid modified acrylic resin;

[0093] 3-10 parts of amino resin;

[0094] 3-5 parts of polyurethane resin;

[0095] 3-5 parts of polyester resin;

[0096] 2-8 parts pigment;

[0097] 2-8 parts of functional filler slurry;

[0098] 3-12 parts of auxiliary agent;

[0099] 5-10 parts organic solvent;

[0100] 30-50 parts water;

[0101] The acrylic resin comprises acrylic resin A with a Tg value of 21-31℃ and a particle size of 80-160nm, and acrylic resin B with a Tg value of 7-17℃ and a particle size of 40-80nm.

[0102] The functional filler slurry is a semi-finished product obtained by pre-mixing ultrafine nano barium sulfate, acrylic resin B, and water.

[0103] Furthermore, the acrylic resin A includes, but is not limited to, one or more of DIC's EMA-1015, EMA-1032, and Wanhua Chemical's ACKETONE2033, and the acrylic resin B includes, but is not limited to, one or more of DIC's EMA-1036, ACW-1011, and Wanhua Chemical's ACKETONE2025. In the water-based paint system of the present invention, selecting the above two different acrylic resins for combination helps to improve the low-temperature reaction rate, appearance, high-temperature resistance, and prevent paint cracking of the prepared water-based paint. When acrylic resin B is used to dissolve and disperse ultrafine nano-barium sulfate, it helps to improve the dispersibility and stability of the functional filler slurry, and improve surface tension and specific gravity.

[0104] Furthermore, the mass ratio of acrylic resin A to acrylic resin B is 2-4:1, which is more advantageous for the water-based paint system of the present invention; for example, the mass ratio of acrylic resin A to acrylic resin B can be 2:1, 2.5:1, 3:1, 3.5:1, 4:1, etc.

[0105] Furthermore, the functional filler slurry is prepared according to the following steps:

[0106] Mix 25-35 parts by weight of acrylic resin B and 45-55 parts by weight of water evenly, add 18-22 parts by weight of ultrafine nano barium sulfate while stirring, stir at 400-600 rpm for 30 minutes, and then grind until the fineness is ≤5μm to obtain the product.

[0107] Furthermore, the acrylic resin B, water, and ultrafine nano barium sulfate were mixed in a weight ratio of 3:5:2.

[0108] Furthermore, the ultrafine nano-barium sulfate is selected from BARIFINE BF-21 and / or BARIFINE BF-25, with an average particle size of 0.3-0.5 μm.

[0109] Furthermore, the weight percentage of the ultrafine nano barium sulfate in the water-based paint is 0.3-5%, more preferably 0.5-2%. For example, the weight percentage of the ultrafine nano barium sulfate in the water-based paint can also be 0.5-1%, 0.5-1.5%, 1-1.5%, 1-2%, 1.5-2%, etc.

[0110] Research has found that introducing ultrafine nano-barium sulfate and preparing it into a functional filler slurry in this invention is key to solving the wetting problem of water-based paints. Compared with additives such as emulsifiers, leveling agents, and wetting and dispersing agents, the functional filler slurry prepared using ultrafine nano-barium sulfate has minimal impact on the adhesion and appearance of water-based paints. This avoids new film problems caused by the introduction of the functional filler slurry, avoids the difficulties in formula design due to the limited addition range of traditional additives, and avoids the increased difficulty in production process control caused by the various process requirements of adding traditional additives.

[0111] Compared to traditional fillers, such as filler slurries prepared with ultrafine talc powder, functional filler slurries prepared with ultrafine nano-barium sulfate are advantageous in obtaining a more suitable specific gravity for paint droplets. This allows the paint droplets to flow into the sealant brush marks more easily and quickly before surface drying, perfectly filling the sealant brush marks. Compared to micron-sized barium sulfate (e.g., Bast 90), functional filler slurries prepared with ultrafine nano-barium sulfate are advantageous in obtaining a more suitable surface tension and particle size distribution for this system. This is beneficial for solving the wetting problem of water-based paints on sealants and does not affect the appearance of the coating or the saturation of the color. In addition, because the particle size of micron-sized barium sulfate is too large after dispersion, it does not help to wet the aforementioned 10-50μm brush mark structure.

[0112] Furthermore, the acid value of the phosphoric acid modified acrylic resin is 160-220 mgKOH / g, including but not limited to one or more of NAC's ACS-1016, ACS-1212, and Lubrizol 2062.

[0113] Furthermore, the amino resin comprises amino resin A with a number-average molecular weight of 600-700, a weight-average molecular weight of 900-1200, and an imino content of 1.5-2.0%, and amino resin B with a number-average molecular weight of 1000-1200, a weight-average molecular weight of 2000-3000, and an imino content of 0.5-1.0%. This invention has found that if both amino resin A and amino resin B react slowly, the sag resistance is poor, and the paint appearance deteriorates; if both react quickly, pinholes are easily formed, affecting the paint film performance and leading to paint defects. In the technical solution of this invention, selecting the aforementioned two different amino resins in combination with other components in the technical solution of this invention helps to improve its anti-sag properties, appearance, and chemical resistance, provides a longer leveling time, and improves its anti-cracking performance. For example, the amino resin A includes, but is not limited to, one or more of Zanxin's CYMEL 202, CYMEL370, and CYMEL 254; the amino resin B includes, but is not limited to, Mitsui Chemicals' UVAN60SE and / or Zanxin's CYMEL 250.

[0114] Furthermore, the mass ratio of amino resin A to amino resin B is 5-9:1, which is more advantageous for the water-based paint system of the present invention; for example, the mass ratio of amino resin A to amino resin B can be 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, etc.

[0115] Furthermore, the polyurethane resin includes, but is not limited to, NAC's N2-4000 and / or DSM's NEOREZ R-9603.

[0116] Furthermore, the polyester resin includes, but is not limited to, one or more of DIC's PRS-1045, NP-6100, and NP-5000.

[0117] Furthermore, the pigment contains 0.1-5 parts of aluminum powder, which is selected from one or more of 4660NS, 4640NS, MH-8801, and 7640NS. Of course, the pigment may also contain pigment components commonly used in the art, such as HOSTAPERM VIOLET RL, EMPEROR 2000 carbon black, Paliotol Gelb L 2140HD, SICOTRANS YELLOW L 1916, IRGAZIN Yellow 5GLT, SR1C, etc. Additionally, it should be noted that the method of using functional filler paste to solve the wetting problem is applicable to water-based paints containing different pigment systems.

[0118] Furthermore, the adjuvant contains 0.1-2 parts of a rheology modifier, which is selected from one or more of BASF's RHEOVISAS1130, ADEKA's ADEKANOL UH-814N, BYK Chemical's BYK-465, and AQUTIX-8461.

[0119] Furthermore, the additive also includes at least one of the commonly used light stabilizers, wetting and dispersing agents, and emulsifiers, in a total mass fraction of 1-5 parts. Preferably, the additive also includes 0.1-1.0 parts of a light stabilizer (e.g., Tinuvin 123), 0.1-1.0 parts of a wetting and dispersing agent (e.g., BYK-192), and 0.7-3 parts of an emulsifier (e.g., FS-640), and the total mass fraction of the light stabilizer, wetting and dispersing agent, and emulsifier reaches 1-5 parts.

[0120] Furthermore, the adjuvant also contains 0.1-2 parts of a pH adjuster, which, exemplarily, includes, but is not limited to, at least one of dimethylethanolamine (DMEA) and triethanolamine.

[0121] Furthermore, the organic solvent has a strong ability to dissolve resins. It can effectively adjust the evaporation rate, which is beneficial for film leveling, and it does not contain benzene-based solvents, including but not limited to ethylene glycol butyl ether, isooctanol, dipropylene glycol methyl ether, ethylene glycol isooctyl ether, ethanol, and one or more of SHELLSOL TK.

[0122] The present invention also provides a method for preparing the above-mentioned water-based paint, comprising the following steps:

[0123] 1) Preparation of functional filler slurry

[0124] In a grinding mill, acrylic resin B and water are mixed evenly according to the formula. Ultrafine nano barium sulfate is added while stirring. After high-speed dispersion for 30 minutes, the mixture is ground to a fineness of ≤5μm to obtain a functional filler slurry. It should be noted that the acrylic resin B and water used in the preparation of the functional filler slurry are not included in the proportion of acrylic resin and water in the water-based paint raw material formula.

[0125] 2) Preparation of mixed resin solution

[0126] Add acrylic resin A and acrylic resin B to container A and stir for 5 minutes. Then add some emulsifier and add amino resin A and amino resin B while stirring. Stir for 20 minutes and adjust the pH value to 8-8.5 with pH adjuster. Then add polyester resin and polyurethane resin and adjust with water to a rotor viscosity B6 of 7000-10000 rpm to obtain a mixed resin solution.

[0127] 3) Preparation of aluminum powder dispersion

[0128] Add some organic solvent and aluminum powder to container B, soak for 15 minutes and stir evenly, then add phosphoric acid modified acrylic resin and stir for 20 minutes. Add emulsifier and other additives (such as wetting and dispersing agents and light stabilizers) while stirring, and stir for 5 minutes to obtain aluminum powder dispersion.

[0129] 4) Preparation of water-based paints

[0130] With stirring, slowly add the aluminum powder dispersion from container B into container A, and stir at 500-600 rpm for 20 minutes.

[0131] Add the functional pigment paste and other pigments (e.g., color paste) to container A while stirring. Stir for 5 minutes, then slowly add some of the auxiliary agent (e.g., rheology modifier). Stir at 500-600 rpm for 15 minutes, then add water, some of the auxiliary agent (e.g., leveling agent), and some of the organic solvent while stirring.

[0132] The pH value is adjusted by a pH adjuster, and the viscosity and solids content are adjusted by water to obtain water-based paint.

[0133] The present invention also provides an application of the water-based paint described above in automotive body painting.

[0134] In application, the prepared water-based paint is applied to a substrate that has been treated with sealant and coated with intermediate paint, then baked at 80°C for 4 minutes, followed by spraying with clear varnish and baking at 140°C for 30 minutes.

[0135] The technical solution of the present invention will be described in detail below through examples.

[0136] Examples 1-5

[0137] Prepare water-based paints according to the formulation amounts in Table 5. See Table 7 for paint and coating film characteristics data.

[0138] Table 5. Water-based paint formulations for Examples 1-5

[0139]

[0140]

[0141] This invention provides a method for preparing water-based paints, the steps of which are as follows:

[0142] 1) Preparation of functional filler slurry

[0143] In a grinding mill, acrylic resin BACW-1011 and water are mixed evenly according to the formula. Under stirring, ultrafine nano barium sulfate BARIFINE BF-21 is added. After high-speed dispersion for 30 minutes, it is ground to a fineness of ≤5μm to obtain functional filler slurry.

[0144] 2) Preparation of mixed resin solution

[0145] Add acrylic resin A EMA-1015 (or EMA-1032) and acrylic resin B ACW-1011 to container A, stir for 5 minutes, then add some emulsifier, and while stirring, add amino resin A CYMEL 254 and amino resin BUVAN60SE, stir for 20 minutes, adjust the pH value to 8-8.5 with pH adjuster DMEA, then add polyester resin NP-5000 and polyurethane resin NEOREZ R-9603, and adjust with water to a rotor viscosity B6 of 7000-10000 rpm to obtain a mixed resin solution.

[0146] 3) Preparation of aluminum powder dispersion

[0147] Add isooctyl alcohol, ethylene glycol isooctyl ether and aluminum powder 4660NS to container B, soak for 15 minutes and stir evenly, then add phosphate modified acrylic resin ACS-1016 and stir for 20 minutes. While stirring, add emulsifier FS-640, wetting and dispersing agent BYK-192 and light stabilizer Tinuvin123, and stir for 5 minutes to obtain aluminum powder dispersion.

[0148] 4) Preparation of water-based paints

[0149] With stirring, slowly add the aluminum powder dispersion from container B into container A, and stir at 500-600 rpm for 20 minutes.

[0150] Add the color paste SR1C and functional pigment paste to container A while stirring. Stir for 5 minutes, then slowly add the rheology modifier ADEKANOL UH-814N. Stir at 500-600 rpm for 15 minutes. While stirring, add pure water, leveling agent BYK-345 and SHELLSOL TK.

[0151] The pH value is adjusted using pH adjuster DMEA, and the viscosity and solids content are adjusted using water to obtain water-based paint.

[0152] Comparative Examples 1-2

[0153] The water-based paint was prepared according to the formulation amounts in Table 6. The preparation steps were the same as in Examples 1-5. The coating and film characteristics data are shown in Table 7.

[0154] Table 6. Waterborne paint formulations for Comparative Examples 1-2

[0155]

[0156]

[0157] Performance Test 2

[0158] The prepared water-based paint was used to prepare a composite coating film. The preparation of the composite coating film was carried out in accordance with conventional methods in the field, and the application process is as follows:

[0159] ED board → partial application of sealant → baking at 135℃ for 25 minutes → water-based dark gray intermediate coat → baking at 140℃ for 20 minutes → water-based color paint → baking at 80℃ for 4 minutes → clear varnish → baking at 140℃ for 30 minutes.

[0160] The conventional sealant is made into a rectangle with dimensions of 75mm*20mm*(2-3)mm on the electrophoresis plate; the sealant used to simulate edge brush treatment is applied by lightly scraping a 75mm*20mm area onto the electrophoresis plate with the edge of a cut tinplate, resulting in a stringy surface (see...). Figure 2 ).

[0161] The film thicknesses of the above-mentioned intermediate coat, color paint, and clear coat are 10-15μm, 8-10μm, and 20-25μm, respectively.

[0162] Table 7. Coating and Coating Film Properties Data

[0163]

[0164] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A water-based paint with high wetting properties on sealants, characterized in that, The water-based paint comprises, by weight parts 20-25 parts acrylic resin; 0.3-1.0 parts of phosphoric acid modified acrylic resin; 3-10 parts of amino resin; 3-5 parts of polyurethane resin; 3-5 parts polyester resin; 2-8 parts pigment; 2-8 parts of functional filler slurry; 3-12 parts of auxiliary agent; 5-10 parts organic solvent; 30-50 parts water; The acrylic resin comprises acrylic resin A with a Tg value of 21-31℃ and a particle size of 80-160nm, and acrylic resin B with a Tg value of 7-17℃ and a particle size of 40-80nm. The functional filler slurry is a semi-finished product obtained by pre-mixing ultrafine nano barium sulfate, acrylic resin B, and water.

2. The water-based paint according to claim 1, characterized in that, The mass ratio of acrylic resin A to acrylic resin B is 2-4:1; Preferably, the acrylic resin A is selected from one or more of DIC's EMA-1015, EMA-1032, and Wanhua Chemical's ACKETONE2033; The acrylic resin B is selected from one or more of DIC's EMA-1036, ACW-1011, and Wanhua Chemical's ACKETONE2025.

3. The water-based paint according to claim 1, characterized in that, The ultrafine nano-barium sulfate is selected from BARIFINE BF-21 and / or BARIFINE BF-25, with an average particle size of 0.03-0.05 μm; Preferably, the ultrafine nano barium sulfate has a weight percentage of 0.3-5% in the water-based paint, more preferably 0.5-2%.

4. The water-based paint according to claim 1, characterized in that, The functional filler slurry was prepared according to the following steps: Mix 25-35 parts by weight of acrylic resin B and 45-55 parts by weight of water evenly, add 18-22 parts by weight of ultrafine nano barium sulfate while stirring, stir at 400-600 rpm for 30 minutes, and then grind until the fineness is ≤5μm to obtain the product.

5. The water-based paint according to claim 1, characterized in that, The acid value of the phosphoric acid modified acrylic resin is 160-220 mg KOH / g; Preferably, the phosphoric acid modified acrylic resin is selected from one or more of NAC's ACS-1016, ACS-1212, and Lubrizol's lubrizol2062.

6. The water-based paint according to claim 1, characterized in that, The amino resin comprises amino resin A with a number average molecular weight of 600-700, a weight average molecular weight of 900-1200, and an imino content of 1.5-2.0%, and amino resin B with a number average molecular weight of 1000-1200, a weight average molecular weight of 2000-3000, and an imino content of 0.5-1.0%. Preferably, the mass ratio of amino resin A to amino resin B is 5-9:1; Preferably, the amino resin A is selected from one or more of Zhanxin's CYMEL 202, CYMEL 370, and CYMEL 254; The amino resin B is selected from Mitsui Chemicals' UVAN60SE and / or Zenshin's CYMEL 250.

7. The water-based paint according to claim 1, characterized in that, The polyurethane resin is selected from NAC's N2-4000 and / or DSM's NEOREZ R-9603; The polyester resin is selected from one or more of DIC's PRS-1045, NP-6100, and NP-5000.

8. The water-based paint according to claim 1, characterized in that, The pigment contains 0.1-5 parts of aluminum powder, wherein the aluminum powder is selected from one or more of 4660NS, 4640NS, MH-8801, and 7640NS; Preferably, the pigment further comprises one or more of HOSTAPERM VIOLET RL, EMPEROR 2000 carbon black, Paliotol Gelb L2140HD, SICOTRANS YELLOW L1916, IRGAZIN Yellow 5GLT, and SR1C.

9. The water-based paint according to claim 1, characterized in that, The adjuvant contains 0.1-2 parts of a rheology modifier, which is selected from one or more of BASF's RHEOVIS AS1130, ADEKA's ADEKANOL UH-814N, BYK Chemical's BYK-465, and AQUTIX-8461. The additives also include at least one of a light stabilizer, a wetting and dispersing agent, and an emulsifier, in a total mass fraction of 1-5 parts.

10. The application of the water-based paint as described in any one of claims 1-9 in automobile body painting.

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