CN-121991576-A - Water-based middle coating with low film thickness and high appearance for automobile and preparation method and application thereof

Abstract

The invention discloses a low-film-thickness high-appearance water-based middle coating for an automobile, and a preparation method and application thereof. The raw materials for forming the aqueous middle coating comprise, by weight, 20-40 parts of aqueous polyester dispersion, 10-20 parts of aqueous acrylic resin, 5-10 parts of amino resin, 2-4 parts of polypropylene glycol oligomer, 1-5 parts of transparent filler paste, 1-3 parts of organic solvent, 1-5 parts of deionized water and auxiliary agents, wherein the aqueous polyester dispersion has a number average molecular weight of 5000-10000, a Tg of 4-10 ℃, an acid value of 3-16KOHmg/g and a hydroxyl value of 10-15KOHmg/g. The aqueous intercoat is used for coating automobiles, can achieve the mechanical and chemical properties of the original coating level under the condition of extremely low dry film thickness (below 16 mu m), and has better properties (such as anti-collision property, anti-falling property and corrosion resistance) and appearance.

Inventors

• CHEN JIANFANG
• LIU NING
• LIU YANG

Assignees

• 立邦汽车涂料(天津)有限公司

Dates

Publication Date

20260508

Application Date

20241031

Claims (10)

1. 1. The low-film-thickness high-appearance water-based middle coating for the automobile is characterized by comprising the following components in parts by weight: 20-40 parts of aqueous polyester dispersion, 10-20 parts of aqueous acrylic resin, 5-10 parts of amino resin, 2-4 parts of polypropylene glycol oligomer, 1-5 parts of transparent filler slurry, 1-3 parts of organic solvent, 1-5 parts of deionized water and auxiliary agents; Wherein the aqueous polyester dispersion has a number average molecular weight of 5000-10000, a Tg of 4-10deg.C, an acid value of 3-16KOHmg/g, and a hydroxyl value of 10-15KOHmg/g.
2. 2. The aqueous basecoat of claim 1, wherein the aqueous polyester dispersion is selected from VYLONAL MD-1335 available from yolkex corporation, allnex corporation At least one or more of AZ 541w/42WA, WATERSOL ZHW-1346 supplied by DIC company, SZ 265G 3-75 supplied by Covestro company, and UCOAT N-800 supplied by Sanyo chemical industry Co., ltd.
3. 3. The aqueous intercoat of claim 1 wherein the minimum film forming temperature of the aqueous acrylic resin is 25-45 ℃; Preferably, the aqueous acrylic resin is selected from at least one or more of XK-82 or XK-86 supplied by EMA-1015S, covestro supplied by Japanese paint Co., ltd, ACW-1033, ACW-1011, and PZW-1001 supplied by Noroo.
4. 4. The aqueous basecoat of claim 1, wherein the polypropylene glycol oligomer has an average number average molecular weight of 950-1050; Preferably, the polypropylene glycol oligomer is selected from one or more of PRIMEPOL PX-1000, SANNIX GP-1000 available from Sanyo chemical industry Co.
5. 5. The aqueous basecoat of claim 1, wherein the mass ratio of the aqueous polyester dispersion, aqueous acrylic resin to polypropylene glycol oligomer is (30-37): (11-13): 2.
6. 6. The aqueous basecoat of claim 1, wherein the amino resin is a partially methylated water soluble amino resin; Preferably, the amino resin is selected from at least one or more of CYMEL 325, CYMEL 370 and CYMEL 250 provided by Allnex corporation.
7. 7. The aqueous middle coating according to claim 1, wherein the auxiliary agent comprises 1-2 parts of defoamer, 1-2 parts of surfactant, 1-5 parts of tackifier and 0.01-0.05 part of pH regulator in parts by weight; preferably, the raw materials further comprise 0-10 parts of black non-transparent filler slurry and/or 0-40 parts of other non-transparent filler slurry.
8. 8. The method for preparing an aqueous intercoat according to any one of claims 1 to 7, comprising the steps of: Sequentially and uniformly mixing transparent filler slurry, polypropylene glycol oligomer, partial deionized water, aqueous polyester dispersion and aqueous acrylic resin; Adding a mixed material formed by partial auxiliary agent and partial deionized water into the obtained material, and then adding a mixed material formed by amino resin, an organic solvent and partial auxiliary agent; and after uniformly mixing, adding the rest deionized water and the rest auxiliary agent, and respectively adjusting the pH value, the viscosity and the brightness to obtain the water-based middle coating.
9. 9. Use of an aqueous basecoat according to any of claims 1 to 7 in automotive low film thickness basecoat applications.
10. 10. The use according to claim 9, characterized in that the dry film thickness of the aqueous intercoat after coating is below 16 μm.

Description

Water-based middle coating with low film thickness and high appearance for automobile and preparation method and application thereof Technical Field The invention relates to the field of water-based automobile paint. More particularly, relates to a low-film-thickness high-appearance automotive water-based middle coating, and a preparation method and application thereof. Background The automobile is light, energy-saving and emission-reducing, is an effective way for realizing carbon neutralization, and has important significance for upgrading the automobile industry and sustainable development of human beings. The current automobile coating generally adopts a four-coating process, namely an electrophoresis layer, a middle coating, a top coating and a varnish layer, the main flow process is 3C1B, the conventional middle coating thickness is generally 25-35 mu m, and the middle coating generally adopts a large amount of barium sulfate and talcum powder as fillers, so that the dry film has high specific gravity and the weight ratio is the largest in the whole coating. Therefore, in order to achieve a better weight reduction of automobiles, it is necessary to achieve a weight reduction of painting by reducing the thickness of the intermediate coating film, and to save energy and reduce emission. Disclosure of Invention Based on the facts, the invention aims to provide a low-film-thickness high-appearance automotive water-based middle coating, and a preparation method and application thereof. The aqueous intercoat is used for coating automobiles, can achieve the mechanical and chemical properties of the original coating level under the condition of extremely low dry film thickness (below 16 mu m), and has better properties (such as anti-collision property, anti-falling property and corrosion resistance) and appearance. In order to achieve the above purpose, the invention adopts the following technical scheme: The low-film-thickness high-appearance water-based intermediate coating for the automobile comprises the following components in parts by weight: 20-40 parts of aqueous polyester dispersion, 10-20 parts of aqueous acrylic resin, 5-10 parts of amino resin, 2-4 parts of polypropylene glycol oligomer, 1-5 parts of transparent filler slurry, 1-3 parts of organic solvent, 1-5 parts of deionized water and auxiliary agents; wherein the aqueous polyester dispersion has a number average molecular weight (Mn) of 5000-10000, a Tg of 4-10 ℃, an acid value of 3-16KOHmg/g, and a hydroxyl value of 10-15KOHmg/g. Further, the aqueous polyester dispersion is selected from VYLONAL MD-1335 available from yolkex corporation, allnex corporationAt least one or more of AZ 541w/42WA, WATERSOL ZHW-1346 supplied by DIC company, SZ 265G 3-75 supplied by Covestro company, and UCOAT N-800 supplied by Sanyo chemical industry Co., ltd. Further, the minimum film forming temperature of the aqueous acrylic resin is 25-45 ℃. Further, the aqueous acrylic resin is selected from at least one or more of XK-82 or XK-86 supplied by EMA-1015S, covestro supplied by Japanese paint Co., ltd, ACW-1033, ACW-1011, and PZW-1001 supplied by Noroo. Further, the polypropylene glycol oligomer has an average number average molecular weight of 950 to 1050, preferably 1000. Further, the polypropylene glycol oligomer is selected from one or more of PRIMEPOL PX-1000, SANNIX GP-1000 available from Sanyo chemical industry Co. Further, the mass ratio of the aqueous polyester dispersion, the aqueous acrylic resin and the polypropylene glycol oligomer is (30-37): 11-13): 2. Further, the amino resin is a partially methylated water-soluble amino resin. Further, the amino resin is selected from at least one or more of CYMEL 325, CYMEL 370 and CYMEL 250 provided by Allnex corporation. Further, the auxiliary agent comprises 1-2 parts of defoaming agent, 1-2 parts of surfactant, 1-5 parts of tackifier and 0.01-0.05 part of pH regulator by weight. Further, the raw materials also comprise 0-10 parts of black non-transparent filler slurry and/or 0-40 parts of other non-transparent filler slurry. In yet another aspect, the present invention provides a method for preparing the aqueous middle coating as described above, comprising the steps of: Sequentially and uniformly mixing transparent filler slurry, polypropylene glycol oligomer, partial deionized water, aqueous polyester dispersion and aqueous acrylic resin; Adding a mixed material formed by partial auxiliary agent and partial deionized water into the obtained material, and then adding a mixed material formed by amino resin, an organic solvent and partial auxiliary agent; and after uniformly mixing, adding the rest deionized water and the rest auxiliary agent, and respectively adjusting the pH value, the viscosity and the brightness to obtain the water-based middle coating. In yet another aspect, the present invention provides the use of an aqueous basecoat as described above in automotive low film thickness basecoat applicati