High-glossiness water-based bi-component polyurethane automobile finish paint and preparation method thereof

Abstract

The invention discloses a high-glossiness water-based bi-component polyurethane automobile finish paint and a preparation method thereof, and belongs to the field of automobile paints. According to the finish paint, a hydroxyl acrylate aqueous dispersion, a water-based hydroxyl polyurethane dispersion A and a water-based hydroxyl polyurethane dispersion B are matched to serve as matrix resin, the hydroxyl content of the hydroxyl acrylate aqueous dispersion is 4.2-5.0%, the hydroxyl content of the water-based hydroxyl polyurethane dispersion A is 2.0-3.2%, the hydroxyl content of the water-based hydroxyl polyurethane dispersion B is 5.0-7.0%, the hydroxyl content of the water-based hydroxyl polyurethane dispersion B is 5.0-7.0%, the hydroxyl content of the water-based hydroxyl polyurethane dispersion A is 5.0-5.0%, and the hydroxyl content of the water-based hydroxyl polyurethane dispersion B is 5.0-5.0%. According to the present invention, the epoxy resin has good compatibility, and the paint film obtained by curing the epoxy resin to form the cross-linked interpenetrating network structure has characteristics of high glossiness, high adhesion, high appearance and high mechanical property so as to meet the requirements of the automobile finish on the performance.

Description

Technical Field

[0001] The invention relates to the field of automobile coatings, and in particular to a high-gloss water-based two-component polyurethane automobile topcoat and a preparation method thereof. Background Art

[0002] In the field of automotive coatings, people's demand for cars is increasing day by day, and the performance requirements for coatings are becoming increasingly stringent. Traditional automotive coatings generally use solvents, and volatile organic solvents have serious environmental pollution and pose a threat to human health. Water-based automotive topcoat is a type of coating that uses water as a solvent. It has lower volatile organic compound (VOCs) emissions and has less impact on the environment and human health. Therefore, automotive topcoats are in urgent need of developing towards water-based. At present, the adhesion and glossiness of water-based automotive topcoats cannot meet the industry development requirements at the same time.

[0003] The glossiness of a car is one of the important indicators to measure its appearance quality. Among them, high-gloss paint products have long dominated the paint market due to their bright colors. How to further improve the glossiness of water-based automotive topcoats is an important part of improving the decorativeness of automotive topcoats. The adhesion of automotive topcoats is also one of the main indicators for testing the quality of paint films. At present, water-based two-component polyurethane automotive topcoats have the problem of shrinkage of the paint film due to the cross-linking and curing process of the paint film, which deteriorates the adhesion with the base paint and affects the glossiness of the surface layer.

[0004] The invention aims to provide a high-gloss water-based polyurethane automobile topcoat with high adhesion and the ability to simultaneously meet various performance requirements of automobile topcoats. Summary of the invention

[0005] The invention provides a high-gloss water-based two-component polyurethane automobile topcoat.

[0006] It consists of component A and component B, and the mass ratio of component A to component B is 5-8:1.

[0007] Among them, the components of component A are, by mass, 7-35 parts of water, 5-15 parts of hydroxy acrylate aqueous dispersion, 25-35 parts of aqueous hydroxy polyurethane dispersion A, 5-7 parts of aqueous hydroxy polyurethane dispersion B, 10-35 parts of titanium dioxide, 0.3-0.7 parts of dispersant, 0.1-0.5 parts of wetting agent, 0.1-0.5 parts of defoaming agent, 0.3-0.5 parts of leveling agent, 1-3 parts of film-forming aid, and 1-3 parts of thickener; the hydroxyl content of the hydroxy acrylate aqueous dispersion is 4.2-5.0%; the hydroxyl content of the aqueous hydroxy polyurethane dispersion A is 2.0-3.2%, and the hydroxyl content of the aqueous hydroxy polyurethane dispersion B is 5.0-7.0%.

[0008] The second component includes a water-dispersible polyisocyanate curing agent.

[0009] In one embodiment, the components of component A are, by mass, 7 parts of water, 5 parts of hydroxy acrylate aqueous dispersion, 25 parts of aqueous hydroxy polyurethane dispersion A, 5 parts of aqueous hydroxy polyurethane dispersion B, 10 parts of titanium dioxide, 0.3 parts of dispersant, 0.1 parts of wetting agent, 0.1 parts of defoaming agent, 0.3 parts of leveling agent, 1 part of film-forming aid, and 1 part of thickener; the hydroxy acrylate aqueous dispersion has a hydroxyl content of 4.2%; the aqueous hydroxy polyurethane dispersion A has a hydroxyl content of 2%, and the aqueous hydroxy polyurethane dispersion B has a hydroxyl content of 5%.

[0010] The second component comprises 9 parts of a water-dispersible polyisocyanate curing agent.

[0011] The relative mass ratio of the aqueous hydroxyl polyurethane dispersion A to the aqueous hydroxyl polyurethane dispersion B is 5-7:1.

[0012] In one embodiment, the aqueous hydroxyl polyurethane dispersion includes aqueous hydroxyl polyurethane dispersion A and aqueous hydroxyl polyurethane dispersion B; the hydroxyl content of aqueous hydroxyl polyurethane dispersion A is 2.0-3.2%, and the hydroxyl content of aqueous hydroxyl polyurethane dispersion B is 5.0-7.0%; the relative mass ratio of aqueous hydroxyl polyurethane dispersion A to aqueous hydroxyl polyurethane dispersion B is 5-7:1, preferably 6:1.

[0013] Preferably, by weight, the hydroxy acrylate aqueous dispersion is 10 parts, the aqueous hydroxy polyurethane dispersion A is 35 parts, and the aqueous hydroxy polyurethane dispersion B is 7 parts.

[0014] Preferably, the aqueous hydroxyl polyurethane dispersion A and the aqueous hydroxyl polyurethane dispersion B are both high molecular weight chain waterborne polyurethanes, preferably aqueous hydroxyl polyether polyurethane dispersions; the solid content of the aqueous hydroxyl polyurethane dispersion A is 35% to 50%, the solid content of the aqueous hydroxyl polyurethane dispersion B is 35% to 50%, and the relative molecular weights are both in the range of 10000-15000. Specifically, the difference between the aqueous hydroxyl polyurethane dispersion A and the aqueous hydroxyl polyurethane dispersion B is the hydroxyl content, and both are high molecular weight chain waterborne polyurethanes. Those skilled in the art can select specific brands of aqueous hydroxyl polyurethane dispersion A and aqueous hydroxyl polyurethane dispersion B within a limited range according to needs, or make aqueous hydroxyl polyether polyurethane dispersions of the corresponding hydroxyl range according to the prior art, without limitation.

[0015] In one embodiment, the water-dispersible polyisocyanate curing agent includes any one or a combination of an adduct of trimethylolpropane and tetramethylol dimethylene diisocyanate, and HDI trimer.

[0016] Preferably, the water-dispersible polyisocyanate curing agent is any one or a combination of Cythane 3174 and Bayhydur XP-7063.

[0017] In one embodiment, the wetting agent is a silicone wetting agent. Specifically, the wetting agent is TG270.

[0018] In one embodiment, the defoaming agent is selected from Tego901w and BYK180.

[0019] In one embodiment, the dispersant is a hydrophilic copolymer dispersant. Specifically, the dispersant is TG755.

[0020] In one embodiment, the leveling agent is any one or a combination of an organosilicon leveling agent and a non-ionic acrylic leveling agent, and preferably, the organosilicon leveling agent and the non-ionic acrylic leveling agent are used together.

[0021] In one embodiment, the aqueous thickener is a polyurethane thickener. Specifically, the polyurethane thickener is any one or a combination of WT-105A, HDA519, RM2020, and BR125P.

[0022] In one embodiment, the titanium dioxide is rutile titanium dioxide. Specifically, the rutile titanium dioxide includes R706 or R5566.

[0023] In one embodiment, the viscosity of component A ranges from 4500 to 5500 cps.

[0024] Furthermore, the coating operation is performed when the components A and B are mixed and diluted to a viscosity range of 300 to 700 cps.

[0025] The present invention also provides a method for preparing any of the above-described quick-drying water-based two-component polyurethane automotive topcoats, the steps being as follows: the preparation process of component A is as follows: water, hydroxy acrylate aqueous dispersion, water-based hydroxy polyurethane dispersion A, water-based hydroxy polyurethane dispersion B, dispersant, wetting agent, defoamer, leveling agent, and film-forming aid are added into a stirring container and stirred evenly at 500 r / min, titanium dioxide is added, and sand-milled at 1200 r / min for 60 minutes until the fineness is less than 30 μm.

[0026] The paint was filtered out using a filter, placed in a new stirring container, a thickener was added, and the mixture was dispersed at a high speed of 1000 r / min for 10 minutes to obtain the component A.

[0027] The component A and the component B are fully mixed and stirred at a mass ratio of 5-8:1 to prepare a quick-drying water-based two-component polyurethane automotive topcoat.

[0028] Based on the above, compared with the prior art, the present invention has the following beneficial effects: 1. The high-gloss water-based two-component polyurethane automotive topcoat provided by the present invention uses hydroxy acrylate aqueous dispersion, water-based hydroxy polyurethane dispersion A and water-based hydroxy polyurethane dispersion B as base resins, and adopts a water-dispersible polyisocyanate curing agent to cure and form a film. The hydroxy acrylate aqueous dispersion is matched with two water-based hydroxy polyurethane dispersions with a specific hydroxyl range, which has good miscibility, and the paint film obtained by curing to form a cross-linked interpenetrating network structure has unexpected gloss. However, the combination of the hydroxy acrylate aqueous dispersion with one of the water-based hydroxy polyurethane dispersions, or any combination of the relative amounts of the two water-based hydroxy polyurethane dispersions, will affect the miscibility of the system, resulting in a large amount of scattered light in the coating after film formation, low gloss, and failure to meet the gloss requirements of the automotive topcoat. 2. In the high-gloss water-based two-component polyurethane automotive topcoat provided by the present invention, the hydroxyl acrylate aqueous dispersion, the water-based hydroxyl polyurethane dispersion A and the water-based hydroxyl polyurethane dispersion B all contain a certain amount of hydroxyl polar groups. While forming a cross-linked structure, the hydroxyl groups can also have a certain interaction force with the substrate, thereby improving the adhesion of the paint film; DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments; the technical features designed in the different implementation modes of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] In the description of the present invention, it should be noted that all terms used in the present invention (including technical terms and scientific terms) have the same meanings as those generally understood by ordinary technicians in the field to which the present invention belongs, and cannot be understood as limiting the present invention; it should be further understood that the terms used in the present invention should be understood to have the same meanings as these terms in the context of this specification and in the relevant fields, and should not be understood in an idealized or overly formal sense, unless explicitly defined in the present invention.

[0031] The comparative examples and example formulations of the present invention are shown in Table 1 and Table 2.

[0032] Table 1 is the formulation of Example 1 and Comparative Examples 1 to 5, where the values ​​are in parts by mass: Component A Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 water 22.5 22.5 22.5 32.5 22.5 22.5 Hydroxyacrylate aqueous dispersion 10 10 10 0 10 10 Waterborne Hydroxylated Polyurethane Dispersion A 35 42 0 35 37.8 33.6 Waterborne Hydroxylated Polyurethane Dispersion B 7 0 42 7 4.2 8.4 Titanium dioxide 20 20 20 20 20 20 Dispersants 0.5 0.5 0.5 0.5 0.5 0.5 Wetting Agents 0.3 0.3 0.3 0.3 0.3 0.3 Defoaming agent 0.3 0.3 0.3 0.3 0.3 0.3 Leveling agent 0.4 0.4 0.4 0.4 0.4 0.4 Film-forming aids 2 2 2 2 2 2 Thickener 2 2 2 2 2 2 Component B Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Polyisocyanate curing agent 15 15 15 15 15 15 Among them, the aqueous polyurethane dispersion A and the aqueous polyurethane dispersion B are both homemade high molecular weight chain aqueous hydroxyl polyether type urethane, the hydroxyl content of aqueous polyurethane dispersion A is 2.0%, the hydroxyl content of aqueous polyurethane dispersion B is 6.6%, and the relative molecular weights of aqueous polyurethane dispersion A and aqueous polyurethane dispersion B are both 10,000.

[0033] The hydroxy acrylate aqueous dispersion is NeoCry1TMXK-540 produced by DSM, which has a hydroxyl content of 4.2% and a solid content of 40%.

[0034] In addition, other components include titanium dioxide R706, dispersant TG755, wetting agent TG270, defoaming agent Tego901w, leveling agent TG700, film-forming aid diethylene glycol butyl ether, and thickener U805.

[0035] The coating preparation method described in Example 1 is as follows: weigh each component according to the formula ratio, add water, hydroxy acrylate aqueous dispersion, aqueous hydroxy polyurethane dispersion A, aqueous hydroxy polyurethane dispersion B, dispersant, wetting agent, defoaming agent, leveling agent, and film-forming aid into a stirring container and stir evenly at 500 r / min, add titanium dioxide, and sand grind at 1200 r / min for 60 min to a fineness of <30 μm.

[0036] The paint was filtered out using a filter, placed in a new stirring container, a thickener was added, and the mixture was dispersed at a high speed of 1000 r / min for 10 minutes to obtain the component A.

[0037] Component A and component B are fully mixed and stirred according to a mass ratio to prepare a high-gloss water-based two-component polyurethane automotive topcoat.

[0038] The coatings described in Comparative Examples 1 to 5 were prepared according to the formulations described in Example 1.

[0039] It should be noted that the specific parameters or some commonly used reagents in the above embodiments are specific embodiments or preferred embodiments of the present invention, rather than limiting the present invention; those skilled in the art can make adaptive adjustments within the scope of the present invention.

[0040] Example 1 and Comparative Examples 1 to 5 were sprayed on a substrate and dried to form a film, and the gloss, adhesion, appearance, and impact resistance performance tests were performed. The test results are shown in Table 3. The test method was carried out in accordance with the relevant test standards.

[0041] Table 3 Performance test results of Example 1 and Comparative Examples 1 to 5: Test items Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Testing standards 60° gloss 90 76 80 69 78 80 GB / T 9754-1988 Adhesion 0 2 1 2 1 1 GB / T 9286-1988 Appearance Smooth Severe shrinkage and shrinkage holes Slight orange peel A small amount of shrinkage, slight orange peel A small amount of pitting A small amount of shrinkage, slight orange peel GB / T 1729-19796 Impact resistance (front / back) (kg·cm) 50 / 50 30 / 30 30 / 40 30 / 40 50 / 30 30 / 40 GB / T 1732-1993 According to the test results, the high-gloss water-based two-component polyurethane automotive topcoat provided by the present invention has excellent gloss, appearance and adhesion, as well as high mechanical properties. The above excellent performance is achieved by using a specific combination of three film-forming resins of hydroxy acrylate aqueous dispersion, water-based hydroxy polyurethane dispersion A and water-based hydroxy polyurethane dispersion B, and a specific ratio range of water-based hydroxy polyurethane dispersion A and water-based hydroxy polyurethane dispersion B, which is also the inventive concept of the present invention.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high gloss water-based two-component polyurethane automotive topcoat, characterized in that: It comprises component A and component B, and the mass ratio of component A to component B is 5-8:1; Wherein, the components of component A are, by mass, 7-35 parts of water, 5-15 parts of hydroxy acrylate aqueous dispersion, 25-35 parts of aqueous hydroxy polyurethane dispersion A, 5-7 parts of aqueous hydroxy polyurethane dispersion B, 10-35 parts of titanium dioxide, 0.3-0.7 parts of dispersant, 0.1-0.5 parts of wetting agent, 0.1-0.5 parts of defoaming agent, 0.3-0.5 parts of leveling agent, 1-3 parts of film-forming aid, and 1-3 parts of thickener; the hydroxy acrylate aqueous dispersion has a hydroxyl content of 4.2-5.0%; the hydroxyl content of aqueous hydroxy polyurethane dispersion A is 2.0-3.2%, and the hydroxyl content of aqueous hydroxy polyurethane dispersion B is 5.0-7.0%; The second component includes a water-dispersible polyisocyanate curing agent.

2. The high gloss water-based two-component polyurethane automotive topcoat according to claim 1, characterized in that: The relative mass ratio of the aqueous hydroxyl polyurethane dispersion A to the aqueous hydroxyl polyurethane dispersion B is 5-7:

1. Requirement 2.

3. The high gloss water-based two-component polyurethane automotive topcoat according to claim 1, characterized in that: The water-dispersible polyisocyanate curing agent includes any one or a combination of an adduct of trimethylolpropane and tetramethylbenzene dimethylene diisocyanate and HDI trimer.

4. The high gloss water-based two-component polyurethane automotive topcoat according to claim 1, characterized in that: The wetting agent is a silicone wetting agent.

5. The high gloss water-based two-component polyurethane automotive topcoat according to claim 1, characterized in that: The dispersant is a hydrophilic copolymer dispersant.

6. The high gloss water-based two-component polyurethane automotive topcoat according to claim 1, characterized in that: The leveling agent is any one or a combination of an organic silicon leveling agent and a non-ionic acrylic leveling agent.

7. The high gloss water-based two-component polyurethane automotive topcoat according to claim 1, characterized in that: The aqueous thickener is a polyurethane thickener.

8. The high gloss water-based two-component polyurethane automotive topcoat according to claim 1, characterized in that: The titanium dioxide is rutile titanium dioxide.

9. A method for preparing the high gloss waterborne two-component polyurethane automotive topcoat as claimed in any one of claims 1 to 9, characterized in that: Here are the steps: The preparation process of component A is as follows: water, hydroxy acrylate aqueous dispersion, aqueous hydroxy polyurethane dispersion A, aqueous hydroxy polyurethane dispersion B, dispersant, wetting agent, defoamer, leveling agent, and film-forming aid are added into a stirring container and stirred evenly at 500 r / min, titanium dioxide is added, and sand-milled at 1200 r / min for 60 min to a fineness of less than 30 μm; the paint is filtered out with a filter, placed in a new stirring container, a thickener is added, and high-speed dispersion is performed at 1000 r / min for 10 min to obtain the component A.