A kind of automobile original exterior water-based black paint and preparation method thereof

Abstract

The present invention belongs to the technical field of automobile coatings, and specifically relates to a kind of automobile original factory exterior water-based black paint and its preparation method. The automobile original factory exterior water-based black paint provided by the present invention comprises the following components and their mass fractions: 25-50 parts of water-based polyurethane resin, 5-15 parts of water-based polyester resin, 1-5 parts of amino resin, 0.5-1 parts of first wetting agent, 0.1-0.5 parts of defoamer, 3-5 parts of thixotropic agent, 3-10 parts of solvent, 10-20 parts of water-based black slurry, 1-3 parts of pH regulator, 1-3 parts of functional additives, 20-30 parts of water; the functional additives include polyethylene glycol and diacetone acrylamide. The automobile original factory exterior water-based black paint provided by the present invention has excellent high-speed shear resistance, stable construction performance, high-pressure water gun resistance, water boiling resistance, excellent heat storage performance, acid resistance, alkali resistance, gasoline resistance, diesel resistance, engine oil resistance, high-speed shear resistance, water resistance, excellent adhesion and other comprehensive performances.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile coatings, and in particular relates to an automobile original exterior water-based black paint and a preparation method thereof. Background Art

[0002] In recent years, with the rapid development of my country's overall economic level and the steady improvement of its comprehensive national strength, people's quality of life has continued to improve. Cars have become mass consumer goods entering thousands of households. The automobile industry has reached a period of rapid development, driving the use of automotive coatings to continue to grow rapidly.

[0003] Traditional paints mostly use organic reagents as solvents, so a large amount of VOCs will be generated during the painting process. Water-based paint generally refers to paint that uses water as a diluent and has a very low organic solvent content. The emergence of water-based paint has greatly reduced the cost of paint and pollution to the environment. Therefore, it has also received great attention in recent years and has now become a hot topic in related fields.

[0004] For example, Chinese patent application CN107057478A discloses a water-based nano-antibacterial ultra-thin automotive interior matte black paint and its preparation method, which comprises: 50-60 parts by weight of water-based chlorinated polypropylene resin, 5-10 parts by weight of nano-antibacterial powder, 3-5 parts by weight of nano-carbon black, 1-2 parts by weight of dispersant, 10-20 parts by weight of deionized water, 5-10 parts by weight of propylene glycol methyl ether, and 2-10 parts by weight of n-butanol. The above raw materials are sequentially put into a cylinder, stirred at 600-800 rpm for more than 15 minutes, then ground to a fineness of ≤15 μm, discharged, and then 0.1-0.5 parts by weight of polyether-modified organic silicon leveling agent and 3-5 parts by weight of matting powder are added, stirred at 1000-1500 rpm for 30 minutes, and the production is completed. Chinese patent application CN106675365A discloses an environmentally friendly UV dual-curing high-gloss black paint and its preparation method. The main paint is prepared by adding 50-60 weight percentages of dual-curing resin, 5-10 weight percentages of acrylic resin, 0.5-1.5 weight percentages of photoinitiator, 0.2-0.8 weight percentages of leveling agent, 0.5-1.5 weight percentages of dispersant, 0.5-3.5 weight percentages of black slurry, and 30-40 weight percentages of solvent in sequence, stirring slowly first, and then stirring at a high speed of 2000-2500 rpm for 30 minutes to prepare the environmentally friendly UV dual-curing high-gloss black paint main paint. The research focus of the above patent application is on how to improve the antibacterial properties of the coating, how to improve the environmental protection, transparency, and compatibility of the colorant in the coating, etc., while ignoring the improvement of the comprehensive properties of the coating, such as water resistance and high-speed shear resistance. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide an original automobile exterior water-based black paint with excellent comprehensive properties such as excellent high-speed shear resistance, stable construction performance, resistance to high-pressure water gun impact, resistance to boiling water, excellent heat storage performance, acid resistance, alkali resistance, gasoline resistance, diesel resistance, engine oil resistance, high-speed shear resistance, water resistance, strong adhesion, etc.

[0006] The technical solution of the present invention is:

[0007] A water-based black paint for original automobile exterior decoration, comprising the following components and their weight fractions: 25-50 parts of water-based polyurethane resin, 5-15 parts of water-based polyester resin, 1-5 parts of amino resin, 0.5-1 parts of first wetting agent, 0.1-0.5 parts of defoaming agent, 3-5 parts of thixotropic agent, 3-10 parts of solvent, 10-20 parts of water-based black slurry, 1-3 parts of pH adjusting agent, 1-3 parts of functional additive, and 20-30 parts of water;

[0008] The functional auxiliary agent includes polyethylene glycol and diacetone acrylamide.

[0009] Furthermore, the original automobile exterior water-based black paint includes the following components and their mass fractions: 38 parts of water-based polyurethane resin, 10 parts of water-based polyester resin, 1.6 parts of amino resin, 0.6 parts of first wetting agent, 0.3 parts of defoaming agent, 4 parts of thixotropic agent, 6 parts of solvent, 15 parts of water-based black slurry, 1.5 parts of pH adjuster, 2 parts of functional additives, and 24 parts of water.

[0010] Furthermore, the functional additive is composed of polyethylene glycol and diacetone acrylamide in a mass ratio of 3-5:15-20.

[0011] Furthermore, the average molecular weight of the polyethylene glycol is 6000.

[0012] The biggest difference between water-based paint and traditional paint is that water is used as the main solvent and only contains a small amount of organic solvent. Therefore, VOC emissions will be significantly reduced and more environmentally friendly. However, the performance and use effect of water-based paint are often not as good as traditional paints because its solvent is mainly water, so the water resistance of the paint film is weak. The present invention has found through extensive research that adding a functional additive composed of polyethylene glycol and diacetone acrylamide to the paint system can effectively improve the water resistance of the paint film.

[0013] Furthermore, the waterborne polyurethane resin is at least one of Covestro 2110, Allnex 6460, and Allnex 6464 (i.e., Allnex DAOTAN® TW 6464 / 36WA); the waterborne polyester resin is at least one of Allnex 6800 (i.e., Allnex VIACRYL® VSC 6800w / 47WA), DSM NEOREZ R1000, DSM NEOREZ R960, and Toyobo MD-1245; the amino resin is at least one of Cytec CYMEL325, Cytec CYMEL327, Cytec CYMEL385, INEOS MF900W / 95, and Yuanbang Resin 1122.

[0014] Resin, as the main film-forming substance of automobile coatings, plays a vital role in the performance of the paint film. The present invention reasonably matches water-based polyurethane resin, water-based polyester resin and amino resin, which can give the coating excellent comprehensive properties, such as resistance to high-pressure water gun impact, resistance to boiling water, excellent heat storage performance, acid resistance, alkali resistance, gasoline resistance, diesel resistance, engine oil resistance, high-speed shear resistance, and excellent adhesion.

[0015] Further, the thixotropic agent is a combination of one or more of Desbaron AQ633E, Desbaron AQ810, Desbaron AQ630, Desbaron AQ600, Core Chemical D777, BASF Rheovis AS 1130, BASF Rheovis AS 1125, BASF PU1191, BYK 8421, and Hemmings 5020.

[0016] Furthermore, the first wetting agent is BYK-347; the defoaming agent is at least one of BYK-011, BYK-015, and TEGO Airex 902W; the solvent is a combination of one or more of ethylene glycol monobutyl ether, propylene glycol butyl ether, ethylene glycol isooctyl ether, and isooctyl alcohol; and the pH adjuster is a 10% by volume aqueous solution of dimethylethanolamine or a 20% by volume aqueous solution of 2-amino-2-methyl-1-propanol.

[0017] Furthermore, the aqueous black slurry includes the following components and their mass percentages: 30-40% carbon black, 4-8% aqueous dispersant, 1-2% second wetting agent, 1-2% neutralizer, 5-10% solvent, and 38-59% water.

[0018] Furthermore, the aqueous dispersant is composed of DISPERBYK-2025 and sodium oleate in a mass ratio of 5-8:1-3.

[0019] In the production and storage of water-based paints, the dispersion of pigments is a crucial link in the coating preparation process. However, due to the unique properties of carbon black such as small particle size, high specific surface area and high oil absorption, it is very difficult to wet, disperse and grind it. The aqueous dispersant composed of DISPERBYK-2025 and sodium oleate added in the preparation of the aqueous black slurry of the present invention can not only be firmly adsorbed on the surface of the pigment particles, so that the dispersed pigment particles are separated, maintain a stable dispersion state, improve the storage stability of the coating, but also improve the blackness and coloring ability of the coating. During the application process, the coating is often subjected to mechanical shear forces, such as high-speed stirring. If the coating has poor shear stability, various quality problems will occur. The present invention has found through a large number of creative experiments that the aqueous dispersant composed of DISPERBYK-2025 and sodium oleate added in the preparation of the aqueous black slurry of the present invention can also improve the high-speed shear resistance of the coating, improve the construction performance of the coating and its appearance decorative performance, etc.

[0020] Furthermore, the second wetting agent is composed of sodium dioctyl sulfosuccinate and wetting agent PE-100 in a mass ratio of 2-3:12-14.

[0021] The second wetting agent composed of sodium dioctyl sulfosuccinate and wetting agent PE-100 added in the preparation of the aqueous black slurry of the present invention can not only improve the wetting performance of the pigment, accelerate the wetting process of the carbon black surface, improve the dispersion efficiency, and give full play to the performance of the dispersant, but also can synergize with the aqueous dispersant to further improve the storage stability of the coating, improve the grinding efficiency, and further improve the blackness, coloring ability and high-speed shear resistance of the coating.

[0022] In addition, the present invention also provides a method for preparing an original automobile exterior water-based black paint, comprising the following steps:

[0023] (1) Add the formulated amount of waterborne polyurethane resin, waterborne polyester resin, water and pH adjuster into a container in sequence, and stir at a speed of 300-600 r / min for 5-10 min to obtain liquid A;

[0024] (2) Adding the formulated amount of thixotropic agent and defoaming agent to the liquid A obtained in step (1) while stirring, and stirring at a speed of 300-600 r / min for 5-10 min to obtain liquid B;

[0025] (3) Add the solvent, aqueous black slurry, amino resin and first wetting agent in the formula amount to the liquid B obtained in step (2), stir at a speed of 300-600 r / min for 10-20 min, add the functional additive, and stir at a speed of 600-800 r / min for 15-25 min to obtain.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] (1) The water-based black paint for automobile original exterior decoration provided by the present invention has high blackness and strong coloring ability, which is suitable for the continuous coating process requirements of the robot in the original paint shop. The hue is stable. After mass production, the color deviation between different workpieces and different positions of the same workpiece at different angles needs to meet the color difference requirements.

[0028] (2) The original automobile exterior water-based black paint provided by the present invention has excellent high-speed shear resistance, stable construction performance, and no clouding or blooming.

[0029] (3) The original automobile exterior water-based black paint provided by the present invention has excellent storage stability.

[0030] (4) The original automobile exterior water-based black paint provided by the present invention has excellent resistance to high-pressure water gun impact, water boiling, and heat storage, and has excellent comprehensive properties such as acid resistance, alkali resistance, gasoline resistance, diesel resistance, engine oil resistance, high-speed shear resistance, good water resistance, and strong adhesion. DETAILED DESCRIPTION

[0031] The present invention is further illustrated below through the description of specific implementation modes, but this is not a limitation of the present invention. Those skilled in the art can make various modifications or improvements based on the basic idea of ​​the present invention, but as long as they do not deviate from the basic idea of ​​the present invention, they are all within the scope of the present invention.

[0032] Unless otherwise specified, the raw materials used in the present invention are commercially available.

[0033] The purchasing information of each raw material in the following examples and comparative examples is shown in Table 1.

[0034] Table 1: Purchase information of each raw material

[0035]

[0036] Example 1: A water-based black slurry

[0037] The aqueous black slurry includes the following components and their mass percentages: 30% carbon black, 4% aqueous dispersant, 1% second wetting agent, 1% neutralizer, 5% solvent, and 59% water; the aqueous dispersant is composed of DISPERBYK-2025 and sodium oleate in a mass ratio of 5:3; the second wetting agent is composed of sodium dioctyl sulfosuccinate and wetting agent PE-100 in a mass ratio of 2:14; the neutralizer is triethanolamine; and the solvent is glycerol.

[0038] The preparation method of the aqueous black slurry is:

[0039] Add water, aqueous dispersant, second wetting agent and solvent into the cylinder, stir at 300r / min for 5min, add carbon black and neutralizer, stir at 800r / min for 25min, and grind to a fineness of less than 10um.

[0040] Example 2: A water-based black slurry

[0041] The aqueous black slurry includes the following components and their mass percentages: 40% carbon black, 8% aqueous dispersant, 2% second wetting agent, 2% neutralizer, 10% solvent, and 38% water; the aqueous dispersant is composed of DISPERBYK-2025 and sodium oleate in a mass ratio of 8:1; the second wetting agent is composed of sodium dioctyl sulfosuccinate and wetting agent PE-100 in a mass ratio of 3:12; the neutralizer is triethanolamine; and the solvent is glycerol.

[0042] The preparation method of the aqueous black slurry is:

[0043] Add water, aqueous dispersant, second wetting agent and solvent into the cylinder, stir at 400r / min for 10min, add carbon black and neutralizer, stir at 1000r / min for 35min, and grind to a fineness of less than 10um.

[0044] Example 3: A water-based black slurry

[0045] The aqueous black slurry includes the following components and their mass percentages: 35% carbon black, 6% aqueous dispersant, 1.8% second wetting agent, 1.6% neutralizer, 7% solvent, and 48.6% water; the aqueous dispersant is composed of DISPERBYK-2025 and sodium oleate in a mass ratio of 7:2; the second wetting agent is composed of sodium dioctyl sulfosuccinate and wetting agent PE-100 in a mass ratio of 3:13.

[0046] The preparation method of the aqueous black slurry is:

[0047] Add water, aqueous dispersant, second wetting agent and solvent into the cylinder, stir at 350r / min for 7min, add carbon black and neutralizer, stir at 900r / min for 30min, and grind to a fineness of less than 10um.

[0048] Example 4: A water-based black paint for original exterior decoration of automobiles

[0049] The original automobile exterior water-based black paint comprises the following components and their weight fractions: 25 parts of water-based polyurethane resin, 5 parts of water-based polyester resin, 1 part of amino resin (CYMEL327), 0.5 parts of first wetting agent, 0.1 parts of defoaming agent, 3 parts of thixotropic agent, 3 parts of solvent, 10 parts of water-based black slurry prepared in Example 1, 1 part of pH adjusting agent, 1 part of functional additive, and 20 parts of water; the functional additive is composed of polyethylene glycol with an average molecular weight of 6000 and diacetone acrylamide in a weight ratio of 5:20; the first wetting agent is BYK-347; the defoaming agent is TEGO® Airex 902W; the thixotropic agent is Desbaron AQ810 and BASF Rheovis® AS 1130 is composed in a mass ratio of 2:1; the solvent is composed of ethylene glycol monobutyl ether, propylene glycol butyl ether and isooctyl alcohol in a mass ratio of 5:2:1; the pH adjuster is a 20% volume fraction of 2-amino-2-methyl-1-propanol aqueous solution.

[0050] The method for preparing the original automobile exterior water-based black paint comprises the following steps:

[0051] (1) Add the formulated amount of waterborne polyurethane resin, waterborne polyester resin, water and pH adjuster into a container in sequence, and stir at a speed of 300 r / min for 5 min to obtain liquid A;

[0052] (2) Adding the formulated amount of thixotropic agent and defoaming agent to the liquid A obtained in step (1) while stirring, and stirring at a speed of 300 r / min for 5 min to obtain liquid B;

[0053] (3) Add the solvent, aqueous black slurry, amino resin and first wetting agent in the formula amount to the liquid B obtained in step (2), stir at a speed of 300 r / min for 10 min, add the functional additive, and stir at a speed of 600 r / min for 15 min to obtain the product.

[0054] Example 5: A water-based black paint for original exterior decoration of automobiles

[0055] The original automobile exterior water-based black paint comprises the following components and their weight fractions: 50 parts of water-based polyurethane resin, 15 parts of water-based polyester resin, 5 parts of amino resin (CYMEL327), 1 part of the first wetting agent, 0.5 parts of defoaming agent, 5 parts of thixotropic agent, 10 parts of solvent, 20 parts of water-based black slurry prepared in Example 2, 3 parts of pH adjusting agent, 3 parts of functional additives, and 30 parts of water; the functional additives are composed of polyethylene glycol with an average molecular weight of 6000 and diacetone acrylamide in a weight ratio of 3:15; the first wetting agent is BYK-347; the defoaming agent is TEGO® Airex 902W; the thixotropic agent is Desbaron AQ810 and BASF's Rheovis®AS 1130 is composed in a mass ratio of 6:1; the solvent is composed of ethylene glycol monobutyl ether, propylene glycol butyl ether and isooctyl alcohol in a mass ratio of 3:2:2; the pH adjuster is a 20% volume fraction of 2-amino-2-methyl-1-propanol aqueous solution.

[0056] The method for preparing the original automobile exterior water-based black paint comprises the following steps:

[0057] (1) Add the formulated amount of waterborne polyurethane resin, waterborne polyester resin, water and pH adjuster into a container in sequence, and stir at a speed of 600 r / min for 10 min to obtain liquid A;

[0058] (2) Adding the formulated amount of thixotropic agent and defoaming agent to the liquid A obtained in step (1) while stirring, and stirring at a speed of 600 r / min for 10 min to obtain liquid B;

[0059] (3) Add the solvent, aqueous black slurry, amino resin and first wetting agent in the formula amount to the liquid B obtained in step (2), stir at a speed of 600 r / min for 20 min, add the functional additive, and stir at a speed of 800 r / min for 25 min to obtain the product.

[0060] Example 6: A water-based black paint for original exterior decoration of automobiles

[0061] The original automobile exterior water-based black paint comprises the following components and their weight fractions: 38 parts of water-based polyurethane resin, 10 parts of water-based polyester resin, 1.6 parts of amino resin (CYMEL327), 0.6 parts of first wetting agent, 0.3 parts of defoaming agent, 4 parts of thixotropic agent, 6 parts of solvent, 15 parts of water-based black slurry prepared in Example 3, 1.5 parts of pH adjusting agent, 2 parts of functional additives, and 24 parts of water; the functional additives are composed of polyethylene glycol with an average molecular weight of 6000 and diacetone acrylamide in a mass ratio of 4:17; the first wetting agent is BYK-347; the defoaming agent is TEGO® Airex 902W; the thixotropic agent is Desbaron AQ810 and BASF's Rheovis® AS 1130 is composed of a mass ratio of 3:1; the solvent is composed of ethylene glycol monobutyl ether, propylene glycol butyl ether and isooctyl alcohol in a mass ratio of 2:3:3; the pH adjuster is a 20% volume fraction of 2-amino-2-methyl-1-propanol aqueous solution.

[0062] The method for preparing the original automobile exterior water-based black paint comprises the following steps:

[0063] (1) Add the formulated amount of waterborne polyurethane resin, waterborne polyester resin, water and pH adjuster into a container in sequence, and stir at a speed of 500 r / min for 8 minutes to obtain liquid A;

[0064] (2) Adding the formulated amount of thixotropic agent and defoaming agent to the liquid A obtained in step (1) while stirring, and stirring at a speed of 400 r / min for 7 minutes to obtain liquid B;

[0065] (3) Add the solvent, aqueous black slurry, amino resin and first wetting agent in the formula amount to the liquid B obtained in step (2), stir at a speed of 450 r / min for 15 min, add the functional additive, and stir at a speed of 700 r / min for 20 min to obtain the product.

[0066] Comparative Example 1: A water-based black slurry

[0067] The composition and preparation method of the aqueous black slurry are similar to those of Example 3;

[0068] The difference from Example 3 is that the aqueous dispersant consists of DISPERBYK-2025 and sodium palmitoleate in a mass ratio of 7:2.

[0069] Comparative Example 2: A water-based black slurry

[0070] The composition and preparation method of the aqueous black slurry are similar to those of Example 3;

[0071] The difference from Example 3 is that the second wetting agent is composed of sodium alkylnaphthalene sulfonate and wetting agent PE-100 in a mass ratio of 3:13.

[0072] Comparative Example 3: A water-based black paint for original automobile exterior

[0073] The composition and preparation method of the original automobile exterior water-based black paint are similar to those of Example 6;

[0074] The difference from Example 6 is that the aqueous black slurry prepared in Comparative Example 1 is used.

[0075] Comparative Example 4: A water-based black paint for original exterior decoration of automobiles

[0076] The composition and preparation method of the original automobile exterior water-based black paint are similar to those of Example 6;

[0077] The difference from Example 6 is that the aqueous black slurry prepared in Comparative Example 2 is used.

[0078] Comparative Example 5: A water-based black paint for original exterior decoration of automobiles

[0079] The composition and preparation method of the original automobile exterior water-based black paint are similar to those of Example 6;

[0080] The difference from Example 6 is that the functional additive is composed of polyethylene glycol with an average molecular weight of 4000 and diacetone acrylamide in a mass ratio of 4:17.

[0081] Comparative Example 6: A water-based black paint for original exterior decoration of automobiles

[0082] The composition and preparation method of the original automobile exterior water-based black paint are similar to those of Example 6;

[0083] The difference from Example 6 is that the functional additive is composed of polyethylene glycol with an average molecular weight of 6000 and diacetone acrylamide in a mass ratio of 17:4.

[0084] Comparative Example 7: A water-based black paint for original exterior decoration of automobiles

[0085] The composition and preparation method of the original automobile exterior water-based black paint are similar to those of Example 6;

[0086] The difference from Example 6 is that the amino resin (CYMEL327) is replaced by INEOS Resimene 717 trimethyl etherified amino resin.

[0087] Test Example 1: Comprehensive Performance Test

[0088] The original automobile exterior water-based black paint prepared in Examples 4 to 6 of the present invention and Comparative Example 7 was matched with PPG water-based primer and two-component clearcoat, and a board test was made on PP material. The process was 3C3B, and the baking conditions were 85°C*30min. The comprehensive performance of the paint film was tested, and the test results are shown in Table 2.

[0089] Table 2 Test results of comprehensive performance of paint film

[0090]

[0091] As can be seen from Table 2, the original automobile exterior water-based black paint prepared in Examples 4 to 6 of the present invention has excellent resistance to high-pressure water gun impact, water boiling, and heat storage, and is resistant to acid, alkali, gasoline, diesel, and engine oil, and has an adhesion of level 0, and has excellent comprehensive performance. Compared with Comparative Example 7, the original automobile exterior water-based black paint prepared in the present invention has better comprehensive performance.

[0092] Test Example 2: Water resistance test

[0093] With reference to GB / T1733-93 "Determination of Water Resistance of Paint Film", the paint films prepared by Examples 4 to 6 of the present invention and Comparative Examples 5 and 6 after the application of the automotive original exterior water-based black paint were tested for water resistance, and the test results are shown in Table 3.

[0094] Table 3 Paint film water resistance test results

[0095]

[0096] It can be seen from Table 3 that after the original car exterior water-based black paint prepared in Examples 4 to 6 of the present invention was applied, the paint film was immersed in 40°C water for 240 hours without discoloration, blistering, or loss of gloss, and the adhesion reached level 0, which has excellent water resistance. Under the same conditions, the paint film after the original car exterior water-based black paint prepared in Comparative Example 5 showed discoloration, blistering, and loss of gloss, and the adhesion was level 1; the paint film after the original car exterior water-based black paint prepared in Comparative Example 6 had serious blistering, discoloration, loss of gloss, and adhesion of level 2. It can be seen that the functional additives composed of polyethylene glycol with an average molecular weight of 6000 and diacetone acrylamide added in the present invention interact with each other and play a role in improving the water resistance of the paint film.

[0097] Test Example 3: High-speed shear resistance test

[0098] The original automobile exterior water-based black paint prepared in Examples 4 to 6 of the present invention and Comparative Examples 3 and 4 was sheared at a speed of 800 r / min for 20 days using a conical paddle stirring device to perform a high-speed shear resistance test. The test results are shown in Table 4.

[0099] Table 4 Test results of high-speed shear resistance of water-based black paint for original automobile exterior

[0100]

[0101] As can be seen from Table 4, the ΔE of the original automobile exterior water-based black paints prepared in Examples 4 to 6 of the present invention are all low, which indicates that the original automobile exterior water-based black paints prepared in the present invention have excellent high-speed shear resistance, among which Example 6 has the lowest ΔE, which is the best example of the present invention. Compared with Comparative Examples 3 and 4, Example 6 of the present invention has better high-speed shear resistance.

Claims

1. A water-based black paint for automobile exterior decoration, characterized in that: The invention comprises the following components and their weight fractions: 25-50 parts of waterborne polyurethane resin, 5-15 parts of waterborne polyester resin, 1-5 parts of amino resin, 0.5-1 parts of first wetting agent, 0.1-0.5 parts of defoaming agent, 3-5 parts of thixotropic agent, 3-10 parts of solvent, 10-20 parts of waterborne black slurry, 1-3 parts of pH adjusting agent, 1-3 parts of functional additive, and 20-30 parts of water; The functional additive is composed of polyethylene glycol and diacetone acrylamide in a mass ratio of 3-5:15-20; the average molecular weight of the polyethylene glycol is 6000.

2. The original automobile exterior water-based black paint according to claim 1, characterized in that: The invention comprises the following components and their weight proportions: 38 parts of waterborne polyurethane resin, 10 parts of waterborne polyester resin, 1.6 parts of amino resin, 0.6 parts of first wetting agent, 0.3 parts of defoaming agent, 4 parts of thixotropic agent, 6 parts of solvent, 15 parts of waterborne black slurry, 1.5 parts of pH adjusting agent, 2 parts of functional additive and 24 parts of water.

3. The original automobile exterior water-based black paint according to claim 1 or 2, characterized in that: The waterborne polyurethane resin is at least one of Covestro 2110, Allnex 6460, and Allnex 6464; the waterborne polyester resin is at least one of Allnex 6800, DSM NEOREZ R1000, DSM NEOREZ R960, and Toyobo MD-1245; the amino resin is at least one of Cytec CYMEL325, Cytec CYMEL327, Cytec CYMEL385, INEOS MF900W / 95, and Yuanbang Resin 1122.

4. The original automobile exterior water-based black paint according to claim 1 or 2, characterized in that: The thixotropic agent is a combination of one or more of Desbaron AQ633E, Desbaron AQ810, Desbaron AQ630, Desbaron AQ600, Core Chemical D777, BASF Rheovis AS 1130, BASF Rheovis AS 1125, BASF PU1191, BYK 8421, and Hemmings 5020.

5. The original automobile exterior water-based black paint according to claim 1 or 2, characterized in that: The first wetting agent is BYK-347; the defoaming agent is at least one of BYK-011, BYK-015, and TEGO Airex 902W; the solvent is a combination of one or more of ethylene glycol monobutyl ether, propylene glycol butyl ether, ethylene glycol isooctyl ether, and isooctyl alcohol; the pH adjuster is a 10% by volume aqueous solution of dimethylethanolamine or a 20% by volume aqueous solution of 2-amino-2-methyl-1-propanol.

6. The original automobile exterior water-based black paint according to claim 1 or 2, characterized in that: The aqueous black slurry comprises the following components and their mass percentages: 30-40% carbon black, 4-8% aqueous dispersant, 1-2% second wetting agent, 1-2% neutralizer, 5-10% solvent, and 38-59% water.

7. The original automobile exterior water-based black paint according to claim 6, characterized in that: The aqueous dispersant is composed of DISPERBYK-2025 and sodium oleate in a mass ratio of 5-8:1-3.

8. The original automobile exterior water-based black paint according to claim 6, characterized in that: The second wetting agent is composed of sodium dioctyl sulfosuccinate and wetting agent PE-100 in a mass ratio of 2-3:12-14.

9. The method for preparing the original water-based black paint for automobile exterior decoration according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) Add the formulated amount of waterborne polyurethane resin, waterborne polyester resin, water and pH adjuster into a container in sequence, and stir at a speed of 300-600 r / min for 5-10 min to obtain liquid A; (2) Adding the formulated amount of thixotropic agent and defoaming agent to the liquid A obtained in step (1) while stirring, and stirring at a speed of 300-600 r / min for 5-10 min to obtain liquid B; (3) Add the solvent, aqueous black slurry, amino resin and first wetting agent in the formula amount to the liquid B obtained in step (2), stir at a speed of 300-600 r / min for 10-20 min, add the functional additive, and stir at a speed of 600-800 r / min for 15-25 min to obtain.

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