High-performance modified water-based acrylic varnish for automobiles

Abstract

The invention discloses a high-performance modified water-based acrylic varnish for automobiles, which is prepared by mixing the following raw materials: modified water-based acrylic resin, a coalescing agent, a water-based anti-settling agent, a water-based dispersing agent and other water-based assistants, the water-based acrylic emulsion is modified by adopting an organosilane flatting agent. The prepared modified water-based acrylic varnish has good leveling performance, the problems that an existing water-based varnish is prone to blistering and sagging and common in weather resistance due to poor leveling performance can be solved, the preparation method of the modified water-based acrylic varnish is simple, production can be conducted under existing equipment, and therefore the modified water-based acrylic varnish is suitable for industrial application and popularization.

Description

Technical Field

[0001] The present invention belongs to the technical field of coating preparation, and particularly relates to a high-performance modified waterborne acrylic clearcoat for automobiles. Background Art

[0002] The use of waterborne automotive coatings is becoming more and more common. Currently, automotive OEMs all use waterborne basecoats in combination with solventborne clearcoats, and their effects can be comparable to those of conventional solventborne automotive coatings, avoiding the defects of easy foaming and poor color retention caused by poor leveling of waterborne clearcoats. However, the high price of imported waterborne coatings has seriously increased the production costs of automobile manufacturers. Therefore, the development of waterborne automotive coatings with good performance is the current research and development focus in the automotive industry. Summary of the Invention

[0003] Aiming at the defects existing in the prior art, the present invention provides a modified waterborne acrylic clearcoat for automobiles, which can solve the problems of heavy orange peel and easy foaming caused by poor leveling of waterborne acrylic emulsions in the current market.

[0004] To achieve the above object, the present invention adopts the following technical solutions: A high-performance modified waterborne acrylic clearcoat for automobiles, which comprises the following components in parts by weight: Modified waterborne acrylic resin: 80 parts; Film-forming aid: 3 parts; Deionized water: 15 parts; Waterborne additive: 3.1 parts.

[0005] Further, the modified waterborne acrylic resin is prepared by mixing a waterborne acrylic emulsion and an organosilane leveling agent in a nitrogen environment in the presence of a catalyst, and maintaining the reaction at 150 - 180 °C for 3 h.

[0006] Furthermore, the catalyst is a platinum-based catalyst, specifically Pt / C, wherein the Pt content is 5 wt% - 20 wt%.

[0007] Furthermore, the carbon atom number of the organosilane leveling agent is less than 6.

[0008] Furthermore, the mass ratio of the waterborne acrylic emulsion, the organosilane leveling agent and the catalyst is 40:1:0.5.

[0009] Further, the film-forming aid is propylene glycol diacetate.

[0010] Further, the waterborne additive comprises the following components in parts by weight: Waterborne anti-settling agent: 0.3 part; Waterborne dispersant: 1 part; Waterborne wetting agent: 0.5 part; 1 part of waterborne ultraviolet absorber; 0.3 part of waterborne defoamer.

[0011] The preparation method of the modified waterborne acrylic clearcoat for automobiles comprises the following steps: (1) Premixing: Under stirring conditions, slowly add the modified waterborne acrylic resin into the film-forming aid, and continue stirring for 5 min to fully mix them; (2) Paint preparation: Then add waterborne additives and deionized water, stir for 10 - 30 min, and then filter to obtain the product.

[0012] Further, the rotation speed of the stirring in step (1) is 800 - 1000 r / min.

[0013] Further, the rotation speed of the stirring in step (2) is 600 - 800 r / min.

[0014] The using method of the modified waterborne acrylic clearcoat for automobiles comprises the following steps: (1) Mix the modified waterborne acrylic clearcoat and the curing agent in a weight ratio of 3:1, and dilute with deionized water until the viscosity of the mixed solution is 25 - 30 S; (2) Spray the basecoat on the surface of the automobile; (3) Spray the mixed solution diluted in step (1) on the basecoat in step (2), and let it flow flat for 10 - 15 minutes; (4) Bake at 70 - 80 °C for 45 - 60 min. After it cools down to room temperature, then place it at normal temperature for 24 - 72 hours.

[0015] Further, the curing agent is an isocyanate curing agent.

[0016] The present invention has the following advantages and beneficial effects: The modified waterborne acrylic clearcoat prepared by the present invention has the following excellent properties and can meet the coating process requirements of automotive coatings: First: It has excellent surface effects, without wrinkling or blistering; it can not be corroded in acidic and alkaline environments and does not damage its performance.

[0017] Second: It has a long shelf life and significant sunscreen and color retention effects; Third: It does not contain harmful solvents such as benzene and is environmentally friendly; Fourth: It does not need to be heated during use, which not only reduces environmental pollution, but also is convenient for operation and reduces labor; Fifth: It has low cost and is relatively cheap compared with imported products; Sixth: The preparation process is simple and can be prepared based on existing equipment, which is suitable for industrialized popularization and application. Specific embodiments

[0018] A modified waterborne acrylic varnish for automobiles, the preparation of which comprises the following steps: (1) Preparation of the modified waterborne acrylic resin: In a nitrogen environment, sequentially add a waterborne acrylic emulsion, a platinum-based catalyst, and 1 / 2 of the raw material amount of an organosilane leveling agent within 0.5 h, and then, under the condition of 150 - 180 °C, while stirring, continue to dropwise add the remaining organosilane leveling agent. After all are added, keep the temperature for reaction for 3 h, cool and discharge to obtain the modified waterborne acrylic resin; (2) Premixing: Under the stirring condition of 800 - 1000 r / min, slowly add 80 parts of the modified waterborne acrylic resin to 3 parts of the film-forming auxiliary propylene glycol diacetate by weight, and continue to stir for 5 min to fully mix them; (3) Paint preparation: Weigh 0.3 part of a waterborne anti-settling agent, 1 part of a waterborne dispersing agent, 0.5 part of a waterborne wetting agent, 1 part of a waterborne ultraviolet absorber, and 0.3 part of a waterborne defoaming agent respectively to prepare a waterborne auxiliary agent; then add it and 15 parts of deionized water to the mixture in step (2), stir at 600 - 800 r / min for 10 - 30 min, and then filter to obtain the modified waterborne acrylic varnish.

[0019] Among them, the catalyst in step (1) is a platinum-based catalyst. The mass ratio of the waterborne acrylic emulsion, the organosilane leveling agent to the platinum-based catalyst used is 40:1:0.5.

[0020] To make the content of the present invention easier to understand, the following further describes the technical solution of the present invention in conjunction with specific embodiments, but the present invention is not limited thereto.

[0021] In the case of clarifying and explaining the object of the present invention through the following examples, the components of the composition are explained with weight parts as the general standard. Without special instructions, for the sake of simplicity, the "parts" described in the embodiments of the present invention have the same meaning as weight parts.

[0022] Specific raw material description: Waterborne acrylic emulsion: Purchased from BASF.

[0023] Organosilane leveling agent: Purchased from BYK Chemie GmbH.

[0024] Catalyst Pt / C: Purchased from Ruike.

[0025] Curing agent: 3300 purchased from Wanhua.

[0026] Waterborne dispersing agent: BYK191 purchased from BYK Chemie GmbH.

[0027] Waterborne defoaming agent: BYK022 purchased from BYK Chemie GmbH.

[0028] Water-based wetting agent: TEGO 4100 was purchased from Degussa.

[0029] Water-based UV absorber: Tinuvin 400 was purchased from BASF Germany.

[0030] Water-based anti-settling agent: 299 was purchased from King Industries.

[0031] The modified water-based acrylic resin used in the examples of the present invention was prepared in the laboratory. The specific preparation method was to introduce nitrogen into a four-necked flask equipped with a condenser and a stirrer, and then sequentially add 40 parts of water-based acrylic emulsion, 0.5 part of catalyst Pt / C and 0.5 part of silicone leveling agent within 0.5 h. Then, at 150 - 180 °C, while stirring, continue to dropwise add 0.5 part of silicone leveling agent. After all the additions were completed, keep the temperature for reaction for 3 h, and then cool and discharge. Examples

[0032] Table 1 Raw material formula

[0033] The preparation method of the modified water-based acrylic varnish includes the following steps: (1) Premixing: According to the formula dosage in Table 1, add the film-forming auxiliary agent to the dispersion tank, stir at 800 r / min, and then slowly add the modified water-based acrylic resin, and continue to stir at 800 r / min for 5 min to fully mix them; (2) Paint preparation: Then add the water-based auxiliary agent and deionized water, stir at 600 r / min for 10 min and then filter to obtain the modified water-based acrylic varnish.

[0034] Comparative examples The preparation method of the modified water-based acrylic varnish includes the following steps: (1) Premixing: By weight, add 3 parts of film-forming auxiliary agent to the dispersion tank, stir at 800 r / min, and then slowly add 80 parts of water-based acrylic resin, 2 parts of silicone leveling agent and 1 part of catalyst Pt / C, and continue to stir at 800 r / min for 5 min to fully mix them; (2) Paint preparation: Then add 1 part of dispersant, 0.5 part of wetting agent, 0.3 part of defoaming agent, 0.3 part of water-based anti-settling agent, 1 part of water-based UV absorber and 15 parts of deionized water, stir at 600 r / min for 10 min and then filter to obtain the modified water-based acrylic varnish.

[0035] Performance testing Spray the obtained modified water-based acrylic varnish on the surface of the metal plate for performance testing. The specific operation is as follows: Ⅰ. Mix the prepared modified waterborne acrylic varnish and the curing agent prepared according to the formulation in Table 2 at a weight ratio of 3:1, dilute with deionized water to adjust the viscosity to 25 - 30S, and then spray it on the metal plate sprayed with waterborne basecoat (spraying pressure is 0.4MPa, control the film thickness at 30 - 40μm), and level for 10 - 15min; Ⅱ. Bake the sprayed metal plate at 70 - 80°C for 40min, test the adhesion, DOI, etc. after cooling, and then test the aging resistance, acid and alkali resistance, gasoline resistance, and water resistance after standing at room temperature for 72h. The specific test methods are shown in Table 3, and the results are shown in Table 4. At the same time, the comparative example and the commercially available oil-based varnish are used as controls.

[0036] Table 2 Raw material formulation of the supporting curing agent

[0037] Table 3 Performance detection methods

[0038] Table 4 Performance detection results

[0039] It can be seen from the results in Table 4 that the modified waterborne acrylic varnish prepared in the examples has excellent performance and meets the coating process requirements of automobile OEMs: that is, the adhesion is 100 / 100 after baking at 70 - 80°C for 40min, the aging resistance is 1000h, the salt spray resistance is 1500h, the acid resistance is 72h, the alkali resistance is 72h, the gasoline resistance is 72h, and the appearance is qualified without shrinkage holes.

[0040] The above are only the preferred embodiments of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope covered by the present invention.

Claims

1. A modified waterborne acrylic varnish for automobiles with high performance, characterized in that: It includes the following components in parts by weight: Modified waterborne acrylic resin: 80 parts; Film-forming auxiliary agent: 3 parts; Deionized water: 15 parts; Waterborne auxiliary agent: 3.1 parts.

2. The modified aqueous acrylic varnish for automobiles according to claim 1, wherein: The modified waterborne acrylic resin is prepared by mixing a waterborne acrylic emulsion with an organosilane leveling agent under a nitrogen environment and in the presence of a catalyst, and holding the reaction at 150 - 180 °C for 3 h.

3. The modified aqueous acrylic clear varnish for automobiles according to claim 2, wherein: The catalyst is a platinum-based catalyst.

4. The modified aqueous acrylic varnish for automobiles according to claim 2, wherein: The mass ratio of the waterborne acrylic emulsion, the organosilane leveling agent to the catalyst used is 40:1:0.

5.

5. The modified aqueous acrylic clear varnish for automobiles according to claim 1, characterized in that: The film-forming auxiliary agent is propylene glycol diacetate.

6. The modified aqueous acrylic clear varnish for automobiles according to claim 1, wherein: The waterborne auxiliary agent includes the following components in parts by weight: Waterborne anti-settling agent: 0.3 part; Waterborne dispersing agent: 1 part; Waterborne wetting agent: 0.5 part; Waterborne ultraviolet absorber: 1 part; Waterborne defoaming agent: 0.3 part.

7. The modified aqueous acrylic clear varnish for automobiles according to claim 1, wherein: Its preparation method comprises the following steps: (1) Premixing: Under stirring conditions, slowly add the modified waterborne acrylic resin into the film-forming auxiliary agent and continue stirring for 5 min; (2) Paint preparation: Then add the waterborne auxiliary agent and deionized water, stir for 10 - 30 min and then filter to obtain the product.

8. The modified aqueous acrylic varnish for automobiles according to claim 7, wherein: The rotation speed of the stirring in step (1) is 800 - 1000 r / min.

9. The modified aqueous acrylic varnish for automobiles according to claim 7, characterized in that: The rotation speed of the stirring in step (2) is 600 - 800 r / min.

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