Aluminum powder premix liquid for oil-based metallic finish, oil-based metallic finish, and preparation method and application thereof

Abstract

The application discloses an aluminum powder premix liquid for oil-based metallic finish, the oil-based metallic finish, and a preparation method and application thereof. According to weight parts, the aluminum powder premix liquid comprises 1 part of aluminum powder, 1-3 parts of solvent, 0.25-2.5 parts of microgel, 0.1-4 parts of amino resin, 0.25-4 parts of cellulose acetate butyrate, and 0.25-4 parts of ethylene-vinyl acetate copolymer wax. By controlling the proportion relationship of the raw materials of the aluminum powder premix liquid, the obtained aluminum powder premix liquid has a remarkable effect on improving the brightness and appearance of the oil-based metallic finish. In addition, the application also provides a method for improving the brightness and appearance of the oil-based metallic finish. The microgel, the amino resin, the cellulose acetate butyrate and the ethylene-vinyl acetate copolymer wax are premixed separately in advance, and then are mixed with an aluminum powder dissolving solution to prepare the aluminum powder premix liquid. The aluminum powder wrapping process can obviously improve the orientation of the aluminum powder and the fineness of the aluminum powder premix liquid, so that the aluminum powder premix liquid can better play an improvement role in the preparation of the oil-based metallic finish.

Description

Technical Field

[0001] This invention relates to the field of oil-based coatings technology. More specifically, it relates to aluminum powder premix for oil-based metallic topcoats, oil-based metallic topcoats, their preparation methods, and applications. Background Technology

[0002] In today's industrial and decorative fields, oil-based metallic paints play a crucial role. From automobile manufacturing and machinery equipment to high-end furniture and architectural hardware, many industries rely on oil-based metallic paints to give metal products excellent protective properties and a superior appearance.

[0003] In the automotive industry, vehicle exterior design is not only a symbol of aesthetics but also a direct reflection of brand image. Consumers have extremely high demands for the gloss and mirror-like finish of automotive paint to showcase smooth and bright body lines. Oil-based metallic paint, with its excellent adhesion and weather resistance, has become the preferred choice for ensuring the long-term appearance quality of vehicles during outdoor driving.

[0004] Despite the widespread application of oil-based metallic topcoats, they still do not fully meet the growing market demand for high-quality oil-based metallic topcoats. Among currently available technologies, one way to improve the gloss of oil-based metallic topcoats is by reducing the film thickness during application. However, this method easily leads to other film defects, such as clouding and uneven coloring. Another method is to directly add CAB resin, EVA wax, fast-drying solvents, and other components that improve the orientation of aluminum powder during the topcoat preparation process. However, there is an upper limit to the amount of these components that can be added; once a certain level is reached, the gloss will not improve further, and it can easily lead to a deterioration in the final film appearance. Regarding improving the appearance of oil-based metallic topcoats, the mainstream methods are as follows: 1) reducing the pigment-to-binder ratio, but this method easily leads to poor hiding power, application hiding power, sandpaper mark hiding power, and problems such as clouding and uneven coloring; 2) replacing with smaller particle size aluminum powder, but this can lead to reduced flicker and visual color difference.

[0005] Therefore, although existing technologies have made some progress in improving the gloss and appearance of oil-based metallic paints, they are still limited by various factors and have failed to provide a more effective way to solve this problem. Further in-depth research is urgently needed to provide better solutions. Summary of the Invention

[0006] Based on this, the first objective of the present invention is to provide an aluminum powder premix for oil-based metallic topcoats.

[0007] The second objective of this invention is to provide a method for preparing the aluminum powder premix liquid for preparing the oily metallic topcoat as described above.

[0008] A third objective of this invention is to provide an application of the aluminum powder premix liquid described above in improving the gloss and appearance of oil-based metallic topcoats.

[0009] The fourth objective of this invention is to provide a method for improving the gloss and appearance of oil-based metallic paints.

[0010] The fifth objective of this invention is to provide an oil-based metallic topcoat.

[0011] The sixth objective of this invention is to provide a method for preparing the oil-based metallic topcoat as described above.

[0012] A seventh object of the present invention is to provide an application of the oil-based metallic topcoat as described above in automotive body painting.

[0013] To achieve the first objective mentioned above, the present invention adopts the following technical solution:

[0014] This invention discloses an aluminum powder premix liquid for oil-based metallic topcoat, wherein the aluminum powder premix liquid contains 1 part aluminum powder by weight.

[0015] Solvent 1-3 parts;

[0016] 0.25-2.5 parts of microgel;

[0017] 0.1-4 parts of amino resin;

[0018] 0.25-4 parts of cellulose acetate butyrate; and

[0019] 0.25-4 parts of ethylene-vinyl acetate copolymer wax.

[0020] Furthermore, by weight, the aluminum powder premix liquid contains

[0021] 1 part aluminum powder;

[0022] Solvent 1-2 parts;

[0023] 0.25-2.5 parts of microgel;

[0024] 0.1-1 part of amino resin;

[0025] 0.25-1 part of cellulose acetate butyrate; and

[0026] 0.25-1 part of ethylene-vinyl acetate copolymer wax.

[0027] To achieve the second objective mentioned above, the present invention adopts the following technical solution:

[0028] This invention discloses a method for preparing the aluminum powder premixed solution as described above, comprising the following steps:

[0029] Aluminum powder is dissolved in a solvent to obtain an aluminum powder solution;

[0030] While stirring, add the remaining solvent, microgel, amino resin, ethylene-vinyl acetate copolymer wax and cellulose acetate butyrate in sequence. After stirring evenly, add aluminum powder solution and stir for 15-20 minutes to control the fineness to below 15 micrometers to obtain aluminum powder premix.

[0031] To achieve the third objective mentioned above, the present invention adopts the following technical solution:

[0032] This invention discloses an application of the aluminum powder premix liquid described above in improving the gloss and appearance of oil-based metallic topcoats.

[0033] To achieve the fourth objective mentioned above, the present invention adopts the following technical solution:

[0034] This invention discloses a method for improving the gloss and appearance of oil-based metallic topcoat, wherein the method involves adding the aluminum powder premix liquid as described above into the raw material of the oil-based metallic topcoat.

[0035] Furthermore, the aluminum powder premix liquid accounts for 5-35 wt% of the total mass of the oil-based metallic topcoat raw materials.

[0036] To achieve the fifth objective mentioned above, the present invention adopts the following technical solution:

[0037] This invention discloses an oil-based metallic topcoat, which, by weight, comprises...

[0038] 5-35 parts of the aluminum powder premix liquid as described above;

[0039] 35-45 parts acrylic resin;

[0040] 8-15 parts of amino resin;

[0041] 0-10 parts of microgel;

[0042] Solvent 14-26 parts.

[0043] Furthermore, by weight, the oil-based metallic topcoat also contains 4-7 parts of additives, including leveling agents, wetting agents, anti-settling waxes, and pH adjusters.

[0044] To achieve the sixth objective mentioned above, the present invention adopts the following technical solution:

[0045] This invention discloses a method for preparing the oil-based metallic topcoat as described above, comprising the following steps:

[0046] While stirring, add acrylic resin, microgel, amino resin, aluminum powder premix and solvent, mix evenly, and adjust to the application viscosity and resistance to obtain oil-based metallic topcoat.

[0047] To achieve the seventh objective mentioned above, the present invention adopts the following technical solution:

[0048] This invention discloses the application of the oil-based metallic topcoat described above in automobile body painting.

[0049] The beneficial effects of this invention are as follows:

[0050] This invention discloses an aluminum powder premix for oil-based metallic topcoats. By introducing microgels, amino resins, cellulose acetate butyrate (CAB resin), ethylene-vinyl acetate copolymer wax (EVA wax), and controlling the ratio between aluminum powder and the above raw materials, it is beneficial to improve the orientation of aluminum powder and the fineness of the aluminum powder premix, so that the obtained aluminum powder premix can better improve the brightness and appearance of oil-based metallic topcoats.

[0051] This invention also discloses a method for preparing the above-mentioned aluminum powder premix liquid. In this method, microgel, amino resin, ethylene-vinyl acetate copolymer wax and a portion of solvent are premixed separately, and then blended with aluminum powder solution to obtain aluminum powder premix liquid. Compared with the prior art of directly adding aluminum powder solution to oil-based metal topcoat, this premixing method can show better improvement in the preparation of oil-based metal topcoat, and is less likely to cause other paint film problems.

[0052] The present invention also discloses an oil-based metallic topcoat, wherein the introduction of the aluminum powder premix liquid obtained above can effectively improve the brightness and appearance of the oil-based metallic topcoat, especially the small-angle brightness (e.g., 15°L and 25°L), and will not cause other paint film problems. Detailed Implementation

[0053] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0054] In the context of illustrating and explaining the purpose of the present invention through the following examples, the components of the composition are explained using parts by weight as a general standard. Unless otherwise specified, for the sake of brevity, "parts" and "parts by weight" are used interchangeably in the embodiments of the present invention.

[0055] According to a specific embodiment of the present invention, the present invention provides an aluminum powder premix liquid for oil-based metallic topcoat, wherein, by weight, the aluminum powder premix liquid comprises...

[0056] 1 part aluminum powder;

[0057] Solvent 1-3 parts;

[0058] 0.25-2.5 parts of microgel;

[0059] 0.1-4 parts of amino resin;

[0060] 0.25-4 parts of cellulose acetate butyrate; and

[0061] 0.25-4 parts of ethylene-vinyl acetate copolymer wax.

[0062] Furthermore, by weight, the aluminum powder premix liquid contains

[0063] 1 part aluminum powder;

[0064] Solvent 1-2 parts;

[0065] 0.25-2.5 parts of microgel;

[0066] 0.1-1 part of amino resin;

[0067] 0.25-1 part of cellulose acetate butyrate; and

[0068] 0.25-1 part of ethylene-vinyl acetate copolymer wax.

[0069] In this aluminum powder premix, microgels, amino resins, cellulose acetate butyrate, and ethylene-vinyl acetate copolymer waxes are introduced to improve the orientation of aluminum powder and the fineness of the premix. The ratio of aluminum powder to the above materials (i.e., microgels, amino resins, cellulose acetate butyrate, and ethylene-vinyl acetate copolymer waxes) is controlled. As a result, the aluminum powder premix can significantly improve the brightness and appearance of oil-based metal topcoats, especially the small-angle brightness (e.g., 15°L and 25°L), without causing other paint film problems.

[0070] The aluminum powder used in this invention is a commercially available product. As an example, the aluminum powder selected in this invention is STAPA ZP11072.

[0071] The addition of microgels is primarily to increase the thixotropic properties of the aluminum powder premix. The microgels used in this invention can be those commonly used in the field of oil-based coatings, and the microgels used to prepare the aluminum powder premix are consistent with those in the oil-based metallic topcoat formulation. As an example, the microgels selected in this invention use ZXS SETALUX-1850-SA-50 resin as the active ingredient, with a solid content adjusted to 25-30 wt%. In some specific embodiments, the solid content of the microgel is 25 wt%, 30 wt%, or 26-29 wt%, etc. In this invention, the microgel using ZXS SETALUX-1850-SA-50 resin as the active ingredient and with a solid content of 25 wt% is designated as SETALUX-1850-SA-25, and the microgel using ZXS SETALUX-1850-SA-50 resin as the active ingredient and with a solid content of 30 wt% is designated as SETALUX-1850-SA-30.

[0072] The addition of amino resin is primarily to stabilize the microgels in the aluminum powder premix and prevent them from coarsening. The amino resin used in this invention can be a commonly used amino resin product in the field of oil-based coatings, and the amino resin used to prepare the aluminum powder premix is ​​consistent with the amino resin in the oil-based metallic topcoat formulation. As examples, the amino resins selected in this invention include, but are not limited to, Changchun Chemical BR 20SE, BR128NP, and Newpes Setamine US-101BB-72.

[0073] Cellulose acetate butyrate can promote the orientation of aluminum powder and, to a certain extent, help the aluminum powder maintain a stable dispersion in the coating, playing a role similar to encapsulation assistance. The cellulose acetate butyrate used in this invention is a commercially available product. As an example, the cellulose acetate butyrate selected in this invention includes, but is not limited to, CAB 381-0.1, CAB 381-0.5, CAB 381-2, and CAB 381-20.

[0074] Ethylene-vinyl acetate copolymer wax can improve the leveling effect of aluminum powder by reducing Bénard vortices. The ethylene-vinyl acetate copolymer wax used in this invention is a commercially available product. As an example, the ethylene-vinyl acetate copolymer wax selected in this invention includes, but is not limited to, BYK Chemical CERAFAK 107 wax additive and Hemings DeuRheo 556S.

[0075] In this invention, the solvent used for the aluminum powder premix solution may be selected from one or more of butyl acetate, xylene, S-100#, S-150#, methanol, n-butanol, propylene glycol methyl ether acetate, DBE, and ethyl acetate.

[0076] According to a specific embodiment of the present invention, the present invention also provides a method for preparing an aluminum powder premix solution, comprising the following steps:

[0077] Aluminum powder is dissolved in a solvent to obtain an aluminum powder solution;

[0078] While stirring, add the remaining solvent, microgel, amino resin, ethylene-vinyl acetate copolymer wax and cellulose acetate butyrate in sequence. After stirring evenly, add aluminum powder solution and stir for 15-20 minutes to control the fineness to below 15 micrometers to obtain aluminum powder premix.

[0079] In this preparation method, the solvent used to dissolve the aluminum powder can be the same as or different from the solvent used to disperse the microgel, amino resin, and other components, and can be adjusted according to actual needs.

[0080] In this preparation method, the stirring rate is controlled at 500-700 r / min.

[0081] According to a specific embodiment of the present invention, the present invention also provides an application of the aluminum powder premix liquid as described above in improving the gloss and appearance of oil-based metallic topcoats.

[0082] According to a specific embodiment of the present invention, the present invention also provides a method for improving the brightness and appearance of oil-based metallic topcoat, the method being to add the aluminum powder premix liquid as described above to the raw material of the oil-based metallic topcoat.

[0083] During the development of this technical solution, it was discovered that modifying the aluminum powder encapsulation process—specifically, pre-mixing the aluminum powder with microgels, amino resins, ethylene-vinyl acetate copolymer wax, and cellulose acetate butyrate—improves the orientation of the aluminum powder and the fineness of the premixed aluminum powder solution. Compared to the existing technology of directly adding the dissolved aluminum powder solution to the raw materials of oil-based metallic topcoats, this method imparts higher gloss and a superior appearance to the oil-based metallic topcoat, especially at small angles (e.g., 15°L and 25°L). Furthermore, since the composition and dosage of the oil-based metallic topcoat remain essentially unchanged, only the method of adding the raw materials is altered; therefore, it does not change the physicochemical properties of the coating itself, nor does it increase the cost of the coating.

[0084] Furthermore, the aluminum powder premix liquid accounts for 5-35 wt% of the total mass of the oil-based metallic topcoat raw materials.

[0085] The aluminum powder premix provided by this invention is applicable to various oil-based metallic topcoat systems for automotive coating, including but not limited to oil-based acrylic systems, oil-based polyester systems, and oil-based alkyd systems. An oil-based acrylic system is provided as an example below.

[0086] According to a specific embodiment of the present invention, the present invention also provides an oil-based metallic topcoat, wherein, by weight, the oil-based metallic topcoat comprises...

[0087] 5-35 parts of aluminum powder premix solution;

[0088] 35-45 parts acrylic resin;

[0089] 8-15 parts of amino resin;

[0090] 0-10 parts of microgel;

[0091] Solvent 14-26 parts.

[0092] In an embodiment of the present invention, the amount of each raw material in the oil-based metallic topcoat formulation is calculated as 100 parts by weight relative to the total mass of the raw materials.

[0093] Preferably, the oil-based metallic topcoat comprises, by weight, parts of...

[0094] 12-32 parts of aluminum powder premix solution;

[0095] 38-43 parts acrylic resin;

[0096] 8-13 parts of amino resin;

[0097] 0-10 parts of microgel;

[0098] Solvent 14-26 parts.

[0099] The acrylic resin used in oil-based metallic topcoats can be a commonly used acrylic resin product in the field of oil-based coatings. As a film-forming resin, the acrylic resin, after undergoing a cross-linking reaction with amino resins, provides various physicochemical properties to the paint film. As an example, the acrylic resins selected in this invention include, but are not limited to, Mitsubishi ACR-8421, Mitsubishi HR-7030, and HR-7107, etc., and their dosage is the conventional addition amount in oil-based metallic topcoats. Preferably, the acrylic resin includes acrylic resin A and acrylic resin B, and acrylic resin A and acrylic resin B are of different types. As an example, acrylic resin A is selected from Mitsubishi ACR-8421, etc., and acrylic resin B is selected from Mitsubishi HR-7030 or HR-7107, etc.

[0100] The amino resin used in oil-based metallic topcoats is generally consistent with the amino resin in the aluminum powder premix. As an example, the amino resins selected in this invention include, but are not limited to, Changchun Chemical BR 20SE, BR128NP, and Newpes Setamine US-101BB-72. Furthermore, in this embodiment, the amount of amino resin used can also be calculated based on its proportion in the total raw materials of the oil-based metallic topcoat, generally accounting for 10-15 wt% of the total raw materials. This proportion also includes the amount of amino resin introduced into the aluminum powder premix.

[0101] The microgels used in oil-based metallic topcoats are generally consistent with those in the aluminum powder premix. Furthermore, in this embodiment, the microgels do not need to be added in excessive amounts to reduce unnecessary waste; they can be added at 5-20 wt% of the total raw material content of the oil-based metallic topcoat, including the amount of microgels introduced from the aluminum powder premix.

[0102] In this embodiment, the selected solvents include, but are not limited to, one or more of butyl acetate, xylene, S-100#, S-150#, methanol, n-butanol, propylene glycol methyl ether acetate, DBE, and ethyl acetate.

[0103] It should be noted that, depending on the needs of the actual application, conventional additives may also be added to the oil-based metallic topcoat, such as leveling agents (BYK-333, BYK-358, BYK-342, etc.), wetting agents (BYK-163, BYK-161, etc.), anti-settling waxes (DISparon 4200-10, DISparon 6901-20X, etc.), and pH adjusters (triethylamine, etc.). If all or part of these additives are added to the aluminum powder premix, they will not have a significant positive effect on the fineness and stability of the aluminum powder premix. On the contrary, additives such as anti-settling waxes will increase the dispersion time and affect the fineness. Therefore, these additives are generally added during the paint manufacturing process.

[0104] According to a specific embodiment of the present invention, the present invention provides a method for preparing the oil-based metallic topcoat as described above, comprising the following steps:

[0105] While stirring, add acrylic resin, microgel, amino resin, aluminum powder premix and solvent, mix evenly, and adjust to the application viscosity and resistance to obtain oil-based metallic topcoat.

[0106] According to one specific embodiment of the present invention, the present invention provides the application of the oil-based metallic topcoat as described above in automotive body painting.

[0107] The technical solution of the present invention will be described below with reference to specific embodiments.

[0108] Examples 1-3

[0109] A method for preparing an oil-based metallic topcoat includes the following steps:

[0110] S1. According to the formula amount in Table 1 for the premixing process, dissolve aluminum powder with butyl acetate to obtain aluminum powder solution for later use.

[0111] S2. While stirring, add xylene, microgel, amino resin, ethylene-vinyl acetate copolymer wax and cellulose acetate butyrate to the container in sequence. Stir for 10 minutes until the mixture is uniform. Then add the aluminum powder solution prepared in S1 and stir for 15 minutes to obtain the aluminum powder premix.

[0112] S3. According to the formula in Table 1, while stirring, add acrylic resin 1, acrylic resin 2, microgel, amino resin, polyethylene wax, polyamide wax, leveling agent, wetting and dispersing agent, DBE, triethylamine, n-butanol, aluminum powder premix obtained in step S2, methanol, ethyl acetate, butyl acetate and xylene to the container, adjust to a suitable viscosity and resistance, and prepare the oily metal topcoat.

[0113] Table 1

[0114]

[0115]

[0116] Comparative Examples 1-4

[0117] A method for preparing an oil-based metallic topcoat includes the following steps:

[0118] S1. According to the formula amount in Table 2 for the premixing process, dissolve aluminum powder with butyl acetate to obtain aluminum powder solution for later use.

[0119] S2. While stirring, add xylene, microgel (if any), amino resin (if any), ethylene-vinyl acetate copolymer wax (if any), and cellulose acetate butyrate (if any) to the container in sequence. Stir for 10 minutes until the mixture is uniform. Then add the aluminum powder solution prepared in S1 and stir for 15 minutes to obtain the aluminum powder premix.

[0120] S3. According to the formulation in Table 2, while stirring, add acrylic resin 1, acrylic resin 2, microgel, amino resin, polyethylene wax, polyamide wax, leveling agent, wetting and dispersing agent, ethylene-vinyl acetate copolymer wax (if any), cellulose acetate butyrate (if any), DBE, triethylamine, n-butanol, the aluminum powder premix obtained in step S2, methanol, ethyl acetate, butyl acetate and xylene to the container, adjust to a suitable viscosity and resistance, and prepare the oily metallic topcoat.

[0121] Table 2

[0122]

[0123]

[0124] Comparative Examples 5-7

[0125] A method for preparing an oil-based metallic topcoat includes the following steps:

[0126] S1. According to the formula amount in Table 3 for the premixing process, dissolve aluminum powder with butyl acetate to obtain aluminum powder solution for later use.

[0127] S2. While stirring, add xylene, acrylic resin 1 (if any), acrylic resin 2 (if any), amino resin (if any), ethylene-vinyl acetate copolymer wax (if any), and cellulose acetate butyrate (if any) to the container in sequence. Stir for 10 minutes until the mixture is uniform, then add the aluminum powder solution prepared in S1 and stir for 15 minutes to obtain the aluminum powder premix.

[0128] S3. According to the formulation in Table 3, while stirring, add acrylic resin 1, acrylic resin 2, microgel, amino resin, polyethylene wax, polyamide wax, leveling agent, wetting and dispersing agent, ethylene-vinyl acetate copolymer wax (if any), cellulose acetate butyrate (if any), DBE, triethylamine, n-butanol, the aluminum powder premix obtained in step S2, methanol, ethyl acetate, butyl acetate and xylene to the container, adjust to a suitable viscosity and resistance, and prepare the oily metallic topcoat.

[0129] Table 3

[0130]

[0131]

[0132] Performance testing

[0133] Plate making:

[0134] 1) Substrate material: ED electrophoresis plate.

[0135] 2) Substrate surface treatment: Degrease the substrate by rinsing it with a mixture of ethanol and toluene (ethanol / toluene = 1:1, v / v).

[0136] 3) Painting method: 3C / 2B.

[0137] 4) Mid-coat selection: ORGA 500 gray.

[0138] 5) Color paint selection: Oil-based metallic topcoat prepared in the examples / comparative examples.

[0139] 6) Varnish selection: MAC O-1880 clear varnish.

[0140] 7) Film thickness control: intermediate coating film thickness 30-40μm; color paint film thickness 11-13μm; clear varnish film thickness 30-40μm.

[0141] 8) Thinner selection: intermediate coat N-178 / N-197; paint N-283 / N-285; varnish EEP / S-100# = 1:1 (v / v).

[0142] 9) Coating viscosity: intermediate coat 22-24 seconds / 4# FORDCUP / 20℃; color paint 13-14 seconds / 4# FORDCUP / 20℃; clear coat 27-28 seconds / 4# FORDCUP / 20℃.

[0143] 10) Spraying conditions: Intermediate coat leveling 6 min 30 s, baking 140℃*20 min; Color paint 1-Color paint 2 flash drying 1 min 35 s, leveling 8 min 45 s; Clear coat leveling 6 min 30 s, baking 140℃*20 min.

[0144] The specific process parameters are shown in Table 4 below.

[0145] Table 4

[0146]

[0147]

[0148] The test results are shown in Tables 5 to 7.

[0149] Table 5

[0150]

[0151] Table 6

[0152]

[0153]

[0154] Table 7

[0155]

[0156]

[0157] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. An aluminum powder premix for oil-based metallic topcoat, characterized in that, By weight, it contains 1 part aluminum powder; Solvent 1-3 parts; 0.25-2.5 parts of microgel; 0.1-4 parts of amino resin; Cellulose acetate butyrate 0.25-4 parts; as well as 0.25-4 parts of ethylene-vinyl acetate copolymer wax.

2. The aluminum powder premixed solution according to claim 1, characterized in that, By weight, it contains 1 part aluminum powder; Solvent 1-2 parts; 0.25-2.5 parts of microgel; 0.1-1 part of amino resin; 0.25-1 part of cellulose acetate butyrate; and 0.25-1 part of ethylene-vinyl acetate copolymer wax.

3. The method for preparing the aluminum powder premixed solution as described in claim 1 or 2, characterized in that, Includes the following steps: Aluminum powder is dissolved in a solvent to obtain an aluminum powder solution; While stirring, add the remaining solvent, microgel, amino resin, ethylene-vinyl acetate copolymer wax and cellulose acetate butyrate in sequence. After stirring evenly, add aluminum powder solution and stir for 15-20 minutes to control the fineness to below 15 micrometers to obtain aluminum powder premix.

4. The application of the aluminum powder premix liquid as described in claim 1 or 2 in improving the gloss and appearance of oil-based metallic topcoats.

5. A method for improving the gloss and appearance of oil-based metallic topcoats, characterized in that, The aluminum powder premix liquid according to claim 1 or 2 is added to the raw material of oil-based metal topcoat.

6. The method according to claim 5, characterized in that, The aluminum powder premix accounts for 5-35 wt% of the total mass of the raw materials for the oil-based metallic topcoat.

7. An oil-based metallic topcoat, characterized in that, By weight, it contains 5-35 parts of the aluminum powder premix liquid according to claim 1 or 2; 35-45 parts acrylic resin; 8-15 parts of amino resin; 0-10 parts of microgel; Solvent 14-26 parts.

8. The oil-based metallic topcoat according to claim 7, characterized in that, By weight, the oil-based metallic topcoat also contains 4-7 parts of additives, including leveling agents, wetting agents, anti-settling waxes, and pH adjusters.

9. The method for preparing an oil-based metallic topcoat as described in claim 7 or 8, characterized in that, Includes the following steps: While stirring, add acrylic resin, microgel, amino resin, aluminum powder premix and solvent, mix evenly, and adjust to the application viscosity and resistance to obtain oil-based metallic topcoat.

10. The application of the oil-based metallic topcoat as described in claim 7 or 8 in automobile body painting.

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