A high-uniformity pearlescent paint for vehicles and its preparation method

Abstract

The present invention belongs to the technical field of coatings, and discloses a preparation method of a high-uniformity automotive pearlescent paint, which comprises the following preparation steps: (1) adding an aqueous polyurethane dispersion 3UD, a multifunctional amine auxiliary agent, and a surfactant into deionized water, and stirring and mixing uniformly to obtain a polymer solution; (2) adding pearlescent powder, propylene glycol monobutyl ether, and a wetting and dispersing agent into deionized water, stirring and mixing uniformly, and then carrying out an immersion treatment to obtain a pearlescent slurry; the immersion time is not less than 12 h; the dosage of the pearlescent powder in the pearlescent paint is not less than 12 wt%; (3) adding the pearlescent slurry obtained in step (2), polyether polyol PPG1000, an aqueous polyamide wax rheology aid P2100W, and a thickener into the polymer solution obtained in step (1), and stirring and mixing uniformly to obtain a high-uniformity automotive pearlescent paint. The formula of the present invention has a good dispersion effect on a high content of pearlescent powder, and the obtained paint film has the advantages of high gloss, good uniformity, good adhesion, high hardness, and good storage stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings, and particularly relates to a high-uniformity automotive pearlescent paint and a preparation method thereof. Background Art

[0002] With the rapid development of the economy and the rapid rise of the automotive industry, cars have become a commonly used means of transportation for people. The automotive industry has a huge demand for automotive coatings. In addition to having relatively high requirements for the variety and conventional properties of coatings, it also requires unique coating properties and construction properties. Therefore, automotive coatings have become a special type of coating.

[0003] Currently, solvent-based automotive coatings are still the main type. A large amount of volatile organic compounds (VOCs) cause serious pollution to the ecological environment during the coating process and also pose great harm to human health. With the implementation of environmental protection regulations, the development of waterborne automotive coatings has become the mainstream direction.

[0004] Pearlescent pigments are a type of optical effect pigment. Because they can present a certain metallic luster, they are also called non-metallic pigments with metallic luster. Pearlescent pigments have the flash effect of metallic pigments and can also produce the soft color of natural pearls. When irradiated by sunlight, they can produce multi-layered reflections, and the reflected light interacts with each other to present a soft and eye-catching or colorful luster and color. Currently, the research on automotive pearlescent paints is also becoming more and more extensive.

[0005] Patent CN112795266A discloses a water-based environmentally friendly pearlescent paint for automobiles. This paint is a one-component water-based paint and is prepared from the following materials in parts by weight: 10-20 parts of water-based modified acrylic resin; 25-30 parts of water-based amino resin; 15-25 parts of water-based pearlescent paste; 1-3 parts of stabilizer; 1-3 parts of wetting agent; 2-5 parts of leveling agent; 1-4 parts of anti-flash rust agent; 0.5-2 parts of defoaming agent; 2-5 parts of thickener; 5-10 parts of film-forming aid; 1-3 parts of adhesion promoter; 5-15 parts of deionized water. This product has good adhesion, hardness, aging resistance and salt spray resistance, and its performance far exceeds that of traditional solvent-based paints. Patent CN 108795263 A discloses a one-component water-based interference pearlescent flash paint for automobiles. The flash paint is prepared by mixing component A, component B and component C in a weight ratio of 2:7:1; Component A includes 30-50 parts by weight of pearlescent pigment, 15-25 parts by weight of dimethyl carbinol, 10-20 parts by weight of ethylene glycol monobutyl ether, 5-10 parts by weight of neopentyl alcohol, 1-5 parts by weight of leveling agent, 2-4 parts by weight of dispersant and 5-12 parts by weight of 2-amino-2-methyl-1-propanol; Component B includes 40-55 parts by weight of water-based polyurethane dispersion and 50-60 parts by weight of deionized water; Component C is an alkali-swellable rheological aid. This patented technology combines a hydrophobic solvent, neopentyl alcohol, with an alkali-swellable rheological aid to effectively prevent the intrusion of water molecules and greatly improve the water resistance of the product.

[0006] However, the prior art generally has the defect that the pearlescent powder is unevenly dispersed and arranged, resulting in uneven gloss. Summary of the Invention

[0007] Aiming at the above-mentioned defects and deficiencies of the prior art, the primary object of the present invention is to provide a preparation method of a high-uniformity pearlescent paint for vehicles.

[0008] Another object of the present invention is to provide a high-uniformity pearlescent paint for vehicles prepared by the above method.

[0009] The object of the present invention is achieved by the following technical solutions:

[0010] A preparation method of a high-uniformity pearlescent paint for vehicles, comprising the following preparation steps:

[0011] (1) Add the water-based polyurethane dispersion 3UD of Guangdong Tongde New Materials Co., Ltd., multifunctional amine auxiliary agent and surfactant to deionized water and stir and mix evenly to obtain a polymer solution;

[0012] (2) Add pearlescent powder, propylene glycol monobutyl ether and wetting and dispersing agent to deionized water, stir and mix evenly, and then soak for treatment to obtain a pearlescent slurry; the soaking time is not less than 12h; the dosage of pearlescent powder in the pearlescent paint is not less than 12wt%;

[0013] (3) Add the pearlescent paste from step (2), polyether polyol PPG1000, aqueous polyamide wax rheology additive P2100W, and thickener to the polymer solution from step (1), stir and mix evenly to obtain a high-uniformity automotive pearlescent paint.

[0014] The weight ratio of pearlescent powder, aqueous polyurethane dispersion 3UD, polyether polyol PPG1000, and aqueous polyamide wax rheology additive P2100W is 12 - 15:27 - 33:3:5.4 - 6.6.

[0015] The aqueous polyamide wax rheology additive P2100W is an aqueous polyamide wax rheology additive developed by Elementis. Its user manual states that it can have better anti-settling and anti-sagging properties in aqueous coatings and can effectively improve the arrangement of metallic pigments. At the same time, due to the strong shear-thinning effect provided by this additive, it is particularly suitable for spraying systems. The P2100W polyamide wax rheology additive is applied to aqueous aluminum powder paint, which can provide better thickening performance, effectively control the settlement of aluminum powder, and improve the arrangement and positioning of aluminum powder in the paint film.

[0016] We found through research that for high-concentration pearlescent powder, if it is dispersed according to the introduction in its manual (this product forms a premixed glue with water and co-solvent, dispersed for 30 - 60 minutes, operating temperature below 30°C, paint addition amount 1 - 6%), a satisfactory effect cannot be achieved.

[0017] The applicant previously applied for ZL202211378621.4, a high-performance black car paint color paste and high-stability black car paint. During the development of this product, we found that the aqueous polyurethane dispersion 3UD is a good dispersion system, which uses specific compound surfactants and wetting and dispersing agents to disperse carbon powder.

[0018] In the study on the dispersion of high-concentration pearlescent powder for this project, the pearlescent powder is relatively light, easy to splash and suspend in the air, and the dosage is relatively high. Therefore, good pearlescent arrangement effects cannot be achieved by using general dispersion means. During the experiment, we found that if the pearlescent powder is less than 12%, the pearlescent arrangement effect can be optimized through the selection of surfactants.

[0019] To solve this problem, during the experiment, the soaking time was extended to more than 12h, which is an important means to solve the problem of poor pearlescent consistent arrangement. It should be particularly noted that: polyether polyol PPG1000 and waterborne polyamide wax rheology aid P2100W are another important means to solve the problem of poor pearlescent consistent arrangement. After the pearlescent powder is soaked, polyether polyol PPG1000 and waterborne polyamide wax rheology aid P2100W are supplemented to ensure good dispersion in waterborne coatings while having good stability. It can completely solve the problem of uneven pearlescent arrangement in the case of high-concentration pearlescent powder usage.

[0020] The optional pearlescent powder in the present invention is from Merck KGaA, Germany, with a particle size of 200 - 600 mesh.

[0021] In the above preparation method of a high-uniformity automotive pearlescent paint, the multifunctional amine aid uses AMP-95.

[0022] The concentration of AMP-95 is 10%. AMP-95 is used to adjust the system pH value to 6 - 8. In practical applications, if ammonia water is used instead, the reaction is rapid, but the smell is strong. If other amine aid neutralizers are used to adjust the acid value, the acid value will change later, and the system dispersion will become poor, resulting in particles.

[0023] In the above preparation method of a high-uniformity automotive pearlescent paint, the surfactant uses a combination of gemini non-ionic surfactant 104E and silicone surfactant BYK-346, and the weight ratio of gemini non-ionic surfactant 104E to silicone surfactant BYK-346 is 1:0.5 - 2.

[0024] In the present invention, both gemini non-ionic surfactant 104E and silicone surfactant BYK-346 mainly play a leveling role, and their synergistic effect further improves the leveling effect.

[0025] In the above preparation method of a high-uniformity automotive pearlescent paint, the weight ratio of each material in step (1) is: 27 - 33 parts of waterborne polyurethane dispersion, 0.5 - 2 parts of multifunctional amine aid, 0.2 - 0.5 parts of surfactant, and 10 - 30 parts of deionized water.

[0026] In the above preparation method of a high-uniformity automotive pearlescent paint, the wetting and dispersing agent in step (2) is an aqueous solution of a copolymer BYK-2012 containing a pigment affinity group.

[0027] In the above preparation method of a high-uniformity automotive pearlescent paint, the weight ratio of each material in step (2) is: 12 - 15 parts of pearlescent powder, 4 - 8 parts of propylene glycol monobutyl ether, 0.3 - 0.8 parts of wetting and dispersing agent, and 10 - 20 parts of deionized water.

[0028] In the above-mentioned preparation method of a high-uniformity automotive pearlescent paint, the thickener described in step (3) is a non-ionic polyurethane thickener 0620. For the non-ionic polyurethane thickener 0620, the thickening effect can be seen in 1 minute. If other types of thickeners are used, such as polyurethane thickener 0630, the dosage will increase by 3 - 5 times, and the thickening speed is slow, about 5 minutes, but the storage stability will be better, and other functional effects are similar;

[0029] If 0620 and 0630 are compounded, the thickening speed will be relatively moderate and suitable for the processing speed;

[0030] When using the thickener, organic solvents such as n-pentanol and PMA are used for dilution, and the concentration is 60%.

[0031] In the above-mentioned preparation method of a high-uniformity automotive pearlescent paint, the weight ratio of each material in step (3) is as follows: polyether polyol PPG1000 3 parts, waterborne polyamide wax rheology aid P2100W 5.4 - 6.6 parts, thickener 2 - 5 parts.

[0032] Meanwhile, the present invention also discloses a high-uniformity automotive pearlescent paint prepared by the method described in any one of the above.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] The present invention uses a waterborne polyurethane dispersion as the film-forming matrix, and is used in combination with a specific gemini non-ionic surfactant and an organosilicon surfactant, as well as a compounded specific dispersant and rheology aid; it has a good dispersion effect on a high content of pearlescent powder, and the obtained paint film has the advantages of high gloss and uniformity, high adhesion and hardness. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is the SEM scanning electron microscope imaging diagram of the pearlescent paint of Example 1 of the present invention; the acceleration voltage is 5000v, and the magnification is adjusted to 200;

[0036] Figure 2 It is the SEM scanning electron microscope imaging diagram of the pearlescent paint of Example 1 of the present invention; the acceleration voltage is 5000v, and the magnification is adjusted to 2000. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The present invention will be further described in detail below with reference to the embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, all parts are by weight.

[0038] Example 1

[0039] A preparation method of a high - uniformity automotive pearlescent paint in this embodiment includes the following preparation steps:

[0040] (1) By weight, 27 parts of aqueous polyurethane dispersion 3UD, 1 part of multifunctional amine auxiliary AMP - 95 (10% solution), 0.1 part of Gemini non - ionic surfactant 104E, and 0.2 part of silicone surfactant BYK - 346 are added to 25 parts of deionized water and stirred and mixed evenly to obtain a polymer solution.

[0041] (2) 15 parts of pearlescent powder, 8 parts of propylene glycol butyl ether, and 0.6 part of wetting and dispersing agent BYK - 2012 are added to 20 parts of deionized water, stirred and mixed evenly, and then soaked for 12 h to obtain a pearlescent slurry.

[0042] (3) The pearlescent slurry in step (2), 5 parts of a dispersant (prepared by mixing 3 parts of polyether polyol PPG1000 and 2 parts of cosolvent n - pentanol), 6.6 parts of aqueous polyamide wax rheology aid P2100W, and 2 parts of non - ionic polyurethane thickener (0620 solution with a concentration of 66%) are added to the polymer solution in step (1), stirred and mixed evenly to obtain a high - uniformity automotive pearlescent paint.

[0043] Example 2

[0044] A preparation method of a high - uniformity automotive pearlescent paint in this embodiment includes the following preparation steps:

[0045] (1) By weight, 30 parts of aqueous polyurethane dispersion 3UD, 1 part of multifunctional amine auxiliary AMP - 95 (10% solution), 0.2 part of Gemini non - ionic surfactant 104E, and 0.1 part of silicone surfactant BYK - 346 are added to 20 parts of deionized water and stirred and mixed evenly to obtain a polymer solution.

[0046] (2) 12 parts of pearlescent powder, 6 parts of propylene glycol butyl ether, and 0.5 part of wetting and dispersing agent BYK - 2012 are added to 16 parts of deionized water, stirred and mixed evenly, and then soaked for 12 h to obtain a pearlescent slurry.

[0047] (3) The pearlescent slurry in step (2), 5 parts of a dispersant (prepared by mixing 3 parts of polyether polyol PPG1000 and 2 parts of cosolvent n - pentanol), 6 parts of aqueous polyamide wax rheology aid P2100W, and 3.2 parts of non - ionic polyurethane thickener (66% 0620 solution) are added to the polymer solution in step (1), stirred and mixed evenly to obtain a high - uniformity automotive pearlescent paint.

[0048] Example 3

[0049] A preparation method of a high - uniformity automotive pearlescent paint in this embodiment includes the following preparation steps:

[0050] (1) By weight, 33 parts of aqueous polyurethane dispersion 3UD, 1 part of multifunctional amine auxiliary AMP-95 (10% solution), 0.2 part of gemini nonionic surfactant 104E, and 0.1 part of silicone surfactant BYK-346 are added to 30 parts of deionized water and stirred and mixed evenly to obtain a polymer solution.

[0051] (2) 13 parts of pearlescent powder, 5 parts of propylene glycol monobutyl ether, and 0.4 part of wetting and dispersing agent BYK-2012 are added to 12 parts of deionized water, stirred and mixed evenly, and then soaked for 12 h to obtain a pearlescent slurry.

[0052] (3) The pearlescent slurry in step (2), 5 parts of a dispersant (prepared by mixing 3 parts of polyether polyol PPG1000 and 2 parts of cosolvent n-amyl alcohol), 5.4 parts of aqueous polyamide wax rheology aid P2100W, and 4 parts of nonionic polyurethane thickener (66% 0620 solution) are added to the polymer solution in step (1), stirred and mixed evenly to obtain a high-uniformity automotive pearlescent paint.

[0053] Example 4

[0054] It is substantially the same as Example 2, except that the amount of aqueous polyamide wax rheology aid P2100W is 6.3 parts, the amount of aqueous polyurethane dispersion 3UD is 28 parts; the pearlescent powder is 13 parts; and the soaking time is extended to 15 h.

[0055] Example 5

[0056] It is substantially the same as Example 2, except that the amount of aqueous polyamide wax rheology aid P2100W is 5.7 parts, the amount of aqueous polyurethane dispersion 3UD is 32 parts; the pearlescent powder is 14 parts; and the soaking time is extended to 14 h.

[0057] Example 6

[0058] It is substantially the same as Example 2, except that the silicone surfactant BYK-346 is removed, and the amount of gemini nonionic surfactant 104E is adjusted to 0.3 part.

[0059] Comparative Example 1

[0060] It is substantially the same as Example 2, except that the soaking time is shortened to 9 h.

[0061] Comparative Example 2

[0062] It is substantially the same as Example 2, except that the soaking time is shortened to 3 h.

[0063] Comparative Example 3

[0064] It is substantially the same as Example 2, except that there is no soaking, and it is directly stirred and dispersed.

[0065] Comparative Example 4

[0066] It is generally the same as Example 2, except that: the waterborne polyamide wax rheology aid P2100W is replaced with Hangzhou Haidis HP-337.

[0067] Comparative Example 5

[0068] It is generally the same as Example 2, except that: the polyether polyol PPG1000 is replaced with Shandong Dongda polyether polyol MN-1000.

[0069] Comparative Example 6

[0070] It is generally the same as Example 2, except that: the dosage of the waterborne polyurethane dispersion 3UD is increased, and the dosage of the polyether polyol PPG1000 is decreased; specifically, the dosage of the waterborne polyurethane dispersion 3UD is increased to 40 parts; the dosage of the polyether polyol PPG1000 is decreased to 1 part.

[0071] Comparative Example 7

[0072] It is generally the same as Example 2, except that: the dosage of the waterborne polyamide wax rheology aid P2100W remains unchanged, and the dosage of the polyether polyol PPG1000 is decreased alone. Specifically, the dosage of the polyether polyol PPG1000 is decreased to 1 part.

[0073] Performance Test

[0074] Test Item 1: Adhesion, referring to GB / T 9286-1998;

[0075] Test Item 2: Hardness, referring to GB / T6739-2006;

[0076] Test Item 3: Glossiness, test angle 60°; referring to GB / T 9754-2007;

[0077] Test Item 4: Scanning electron microscope photograph of the coating pearlescent flakes.

[0078] The performance test results are shown in Table 1 below.

[0079] Table 1

[0080] Glossiness Adhesion Hardness Storage stability Example 1 99 1 H 8 Example 2 112 0 2H 10 Example 3 100 0 2H 8 Example 4 115 0 2H 8 Example 5 100 0 2H 8 Example 6 98 1 2H 6 Comparative example 1 99 1 H 6 Comparative example 2 98 1 H 6 Comparative example 3 95 2 HB 6 Comparative example 4 99 0 2H 6 Comparative example 5 98 1 2H 6 Comparative example 6 100 1 H 8 Comparative example 7 102 0 H 8

[0081] As can be seen from the results in Table 1, the present invention uses a waterborne polyurethane dispersion as a film-forming matrix, and is used in combination with a specific gemini nonionic surfactant and an organosilicon surfactant, as well as a compounded specific dispersant and rheology aid; it has a good dispersion effect on high-content pearlescent powder, and the obtained paint film has the advantages of high glossiness and uniformity, high adhesion and high hardness.

[0082] By Figure 1 and Figure 2 performing SEM scanning electron microscopy imaging on the pearlescent paint of the present invention with an acceleration voltage of 5000 v, adjusting the magnification to 200 - 2000, and observing the film morphology, it can be seen that the coating is evenly distributed on the film surface, the pearlescent consistency is well arranged, the pearlescent powder is perfectly coated, and the glossiness is good.

[0083] As can be seen from Table 1 of the present invention, compared with Comparative Examples 1 - 3, Example 2 has the advantages of higher glossiness and storage stability. The fundamental reason is that soaking can improve the surface affinity of the pearlescent powder and the dispersion uniformity of the pearlescent powder. The pearlescent pigment and the matrix are arranged and distributed more evenly, with good pearlescent effect, and also have good thixotropic effect and good storage stability.

[0084] By comparing Example 2 with Comparative Examples 4 and 5, after replacing the waterborne polyamide wax rheology aid P2100W with Hangzhou Haidis HP - 337, its advantage is that the latter has better storage stability and orientation arrangement effect. The fundamental reason is that P2100W expands and activates in the pre - dispersed state to exhibit excellent thixotropy, and strengthens the uniform arrangement of the pigment, increasing the film glossiness; from Comparative Example 5, it can be concluded that polyether polyol PPG1000 has strong irreplaceability in this product.

[0085] By comparing Example 2 with Comparative Example 6, the ratio of the waterborne polyurethane dispersion 3UD, polyether polyol PPG1000 and the proper ratio of compounding with the waterborne polyamide wax rheology aid P2100W are relatively important; by comparing Example 2 with Comparative Example 7, simply reducing the amount of polyether polyol PPG1000 will result in uneven dispersion of the matrix and a trace amount of colloidal particle phenomenon, indicating that PPG1000 has a solubilizing and wetting effect on the system. Regarding the internal synergistic relationship between PPG1000, 3UD and P2100W, due to the confidentiality of raw material details, further research is still needed. The existing research can only draw the above conclusions.

[0086] The above - mentioned embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above - mentioned embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A preparation method of a high - uniformity automotive pearlescent paint, characterized in that, It includes the following preparation steps: (1) Add aqueous polyurethane dispersion 3UD, multifunctional amine auxiliary agent, and surfactant into deionized water, stir and mix evenly to obtain a polymer solution; (2) Add pearlescent powder, propylene glycol monobutyl ether, and wetting and dispersing agent into deionized water, stir and mix evenly, and then soak for treatment to obtain a pearlescent slurry; the soaking time is not less than 12 h; the dosage of pearlescent powder in the pearlescent paint is not less than 12 wt%; (3) Add the pearlescent slurry in step (2), polyether polyol PPG1000, aqueous polyamide wax rheology aid P2100W, and thickener into the polymer solution in step (1), stir and mix evenly to obtain a high-uniformity automotive pearlescent paint; The weight ratio of pearlescent powder, aqueous polyurethane dispersion 3UD, polyether polyol PPG1000, and aqueous polyamide wax rheology aid P2100W is 12 - 15:27 - 33:3:5.4 - 6.6; the multifunctional amine auxiliary agent uses AMP-95; the surfactant uses a combination of gemini non-ionic surfactant 104E and silicone surfactant BYK-346; the weight ratio of gemini non-ionic surfactant 104E and silicone surfactant BYK-346 is 1:0.5 - 2.

2. The preparation method of a high - uniformity automotive pearlescent paint according to claim 1, characterized in that, In step (1), the weight ratio of each material is: 27 - 33 parts of aqueous polyurethane dispersion, 0.5 - 2 parts of multifunctional amine auxiliary agent, 0.2 - 0.5 parts of surfactant, and 10 - 30 parts of deionized water.

3. The preparation method of a high - uniformity automotive pearlescent paint according to claim 1, characterized in that, In step (2), the wetting and dispersing agent is an aqueous copolymer solution BYK-2012 containing pigment affinity groups.

4. The preparation method of a high - uniformity automotive pearlescent paint according to claim 2 or 3, characterized in that, In step (2), the weight ratio of each material is: 12 - 15 parts of pearlescent powder, 4 - 8 parts of propylene glycol monobutyl ether, 0.3 - 0.8 parts of wetting and dispersing agent, and 10 - 20 parts of deionized water.

5. The preparation method of a high - uniformity automotive pearlescent paint according to claim 1, characterized in that, In step (3), the thickener is a non-ionic polyurethane thickener.

6. The preparation method of a high - uniformity automotive pearlescent paint according to claim 5, characterized in that, In step (3), the weight ratio of each material is: 3 parts of polyether polyol PPG1000, 5.4 - 6.6 parts of aqueous polyamide wax rheology aid P2100W, and 2 - 5 parts of thickener.

7. A high - uniformity automotive pearlescent paint, characterized in that, It is prepared by the method described in any one of claims 1 - 6.

Images