Vacuum coating UV wire drawing finish and its preparation method and application

Abstract

The application discloses a UV wire-drawing finish for vacuum coating and a preparation method and application thereof, and the preparation raw materials comprise, in terms of weight parts, fluorocarbon modified UV polyurethane resin 20-30 parts, polyurethane acrylic resin 10-20 parts and nano modified UV polyurethane resin 20-30 parts. The application provides the UV wire-drawing finish for vacuum coating and the preparation method and application thereof, so as to solve the problems of slow curing of the paint film, poor steel wool resistance, anti-graffiti and anti-glare effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology, in particular to a UV wire-drawing finish for vacuum plating and a preparation method and application thereof. BACKGROUND

[0002] Modern industrial coating is one of the most important process links in manufacturing. It plays an extremely important role in improving the commodity nature, decoration of products, prolonging the service life of products and providing special functions. With the use of mobile online office, mobile online education and new energy vehicles, the frequency is greatly improved, and the appearance of electronic products is required to have anti-glare effect, anti-graffiti, high wear resistance and good hand feeling. As electronic products and vehicles are becoming lighter and thinner, the requirements for coating film are also increasing. When the film is less than 10 microns, the above requirements are met while the flexibility and hardness are guaranteed, so the quality of the coating is required to be high. The existing ordinary wear-resistant matte UV cannot meet the thin coating, anti-glare and poor wear resistance of AG coating.

[0003] Therefore, there is an urgent need for a UV wire-drawing finish for vacuum plating with good anti-glare effect. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application provides a UV wire-drawing finish for vacuum plating and a preparation method and application thereof, to solve the problems of poor anti-steel wool, anti-graffiti and anti-glare effect.

[0005] The present application also provides a preparation method of the above-mentioned UV wire-drawing finish for vacuum plating.

[0006] The present application also provides the application of the above-mentioned UV wire-drawing finish for vacuum plating in electronic product shells.

[0007] According to one aspect of the present application, a UV wire-drawing finish for vacuum plating is provided, and the preparation raw materials include, by weight: fluorocarbon modified UV polyurethane resin 20-30 parts, polyurethane acrylic resin 10-20 parts, and nano modified UV polyurethane resin 20-30 parts.

[0008] According to the embodiments of the first aspect of the present application, at least the following beneficial effects are achieved:

[0009] The UV finish of the present application has excellent anti-steel wool, anti-graffiti and anti-glare effects. The fluorocarbon groups of the fluorocarbon modified UV polyurethane resin provide superhydrophobicity for the coating, enhance the anti-graffiti and anti-fingerprint performance, reduce the surface tension of the coating, and improve the excellent properties such as heat resistance and chemical corrosion resistance. The polyurethane groups have good wear resistance and flexibility, so that the coating has high wear resistance and good physical properties.

[0010] The nanoparticles of the nano-modified UV polyurethane resin reduce shrinkage during curing by limiting the movement of polymer chains, form chemical bonds with the functional groups of the resin matrix, improve adhesion, enhance the bonding between the resin and the metal substrate, increase the hardness of the coating, reduce wear and tear, and improve toughness by absorbing impact energy, promoting plastic deformation, or preventing crack propagation.

[0011] In some embodiments of the present application, the polyurethane acrylic resin comprises a 9-15 functional polyurethane acrylic resin.

[0012] The 9-15 functional polyurethane acrylic resin described above has a relatively large number of functional groups and a relatively short chain length, and has high hardness, thereby improving the wear resistance of the paint film.

[0013] The addition of acrylic polyurethane wax paste and matt powder can improve the wear resistance of the coating, and the microcrystalline structure of the wax helps to scatter light, increasing the anti-glare effect of the coating.

[0014] Promote rapid curing: In UV curing coatings, the multi-functional group characteristics of DPEHA enable it to quickly form a hard and transparent coating through photo-induced polymerization

[0015] In some embodiments of the present application, the fluorocarbon-modified UV polyurethane resin comprises Bluecoat L-6905B.

[0016] In some embodiments of the present application, the fluorocarbon-modified UV polyurethane resin has a solid content of 98%, a viscosity of 15000-25000 cps / 25°C, and an acid value of 1 mgKOH / g.

[0017] In some embodiments of the present application, the nano-modified UV polyurethane resin has a solid content of 90%, a viscosity of 1000-2000 cps / 25°C.

[0018] High solid content can reduce the amount of solvent used, increase the thickness and quality of the coating film, and suitable viscosity facilitates processing, improves coating uniformity, and improves workability, etc. High solid content and suitable viscosity help to reduce material waste and improve material utilization, thereby reducing production costs.

[0019] In some embodiments of the present application, the nano-modified UV polyurethane resin comprises UA-895 from Zhongshan Jiesida.

[0020] In some embodiments of the present application, the polyurethane acrylic resin comprises 6196-100 from Changxing Chemical.

[0021] In some embodiments of the present application, the acrylic polyurethane wax paste comprises BG-06 from Gifu, Japan.

[0022] In some embodiments of the present application, the dispersant includes BYK110 polymeric phosphate ester solution.

[0023] In some embodiments of the present application, the photoinitiator includes at least one of Irgacure 184 and Darocur TPO from BASF.

[0024] In some embodiments of the present application, the raw material for preparing the UV wire drawing finish for vacuum coating further includes an additive.

[0025] The additive includes acrylic polyurethane wax paste, matting powder, photoinitiator, dispersant, diluent, and leveling agent.

[0026] The wax in the acrylic polyurethane wax paste has a microcrystalline structure that helps to scatter light, increasing the anti-glare effect of the coating.

[0027] In some embodiments of the present application, the raw material for preparing the UV wire drawing finish for vacuum coating further includes aliphatic polyurethane resin.

[0028] In some embodiments of the present application, the raw material for preparing the UV wire drawing finish for vacuum coating further includes a hexafunctional monomer, and the hexafunctional monomer includes dipentaerythritol hexaacrylate.

[0029] The dipentaerythritol hexaacrylate in the present application has six acrylic functional groups, which can quickly polymerize with various monomers or polymers through photopolymerization to form a three-dimensional network structure, having high reactivity.

[0030] In some embodiments of the present application, the diluent includes at least one of methyl isobutyl ketone, diacetone alcohol, and butyl acetate.

[0031] In some embodiments of the present application, the diluent includes methyl isobutyl ketone, diacetone alcohol, and butyl acetate.

[0032] In some embodiments of the present application, the diluent includes, by weight fraction, 9-12 parts of methyl isobutyl ketone, 8-12 parts of diacetone alcohol, and 9-15 parts of butyl acetate.

[0033] The diluent in the above weight fraction helps to improve the performance stability and water resistance of the final product.

[0034] In some embodiments of the present application, the raw material includes, by weight fraction, 20-30 parts of fluorocarbon-modified UV polyurethane resin, 10-20 parts of polyurethane acrylic resin, 20-30 parts of nano-modified UV polyurethane resin, 10 parts of aliphatic polyurethane resin, 5-8 parts of acrylic polyurethane wax paste, 5-7 parts of matting powder, 3-5 parts of photoinitiator, 1-2 parts of dispersant, 20-30 parts of diluent, and 0.5-10 parts of leveling agent.

[0035] In some embodiments of the present application, the preparation raw materials include, by weight parts, fluorocarbon modified UV polyurethane resin 20-30 parts, polyurethane acrylic resin 10-20 parts, nano modified UV polyurethane resin 20-30 parts, aliphatic polyurethane resin 10 parts, acrylic polyurethane wax paste 5-8 parts, matting powder 5-7 parts, six monomer 5-6 parts, photoinitiator 3-5 parts, dispersant 1-2 parts, diluent 20-30 parts and leveling agent 0.5-10 parts.

[0036] In some embodiments of the present application, the leveling agent includes polyether modified polydimethylsiloxane.

[0037] According to two aspects of the present application, a preparation method of a wire drawing finish is provided, including: mixing and reacting the preparation raw materials of the vacuum coating film UV wire drawing finish.

[0038] In some embodiments of the present application, the preparation method of the wire drawing finish includes:

[0039] S1. Preheat the polyurethane acrylic resin, nano modified UV polyurethane resin and fluorocarbon modified UV polyurethane resin to obtain a premix 1;

[0040] S2. Add the photoinitiator to part of the diluent to obtain a premix 2;

[0041] S3. Add the premix 2 to the premix 1 and mix;

[0042] S4. Add the six monomer, dispersant, matting powder, acrylic polyurethane wax paste, leveling agent and the remaining diluent to step S3 and mix to obtain the vacuum coating film UV wire drawing finish.

[0043] In some embodiments of the present application, step S3 further includes filtering after the mixing.

[0044] Thereby the mixing uniformity of the vacuum coating film UV wire drawing finish can be further improved and large particle impurities therein can be removed.

[0045] According to three aspects of the present application, a composite coating is provided, which includes a primer layer, an electroplating film layer, a middle coating layer and a top coating layer arranged in sequence;

[0046] The preparation raw materials of the top coating layer include the vacuum coating film UV wire drawing finish.

[0047] In some embodiments of the present application, the arrangement method includes:

[0048] D1. Spray the treatment agent on the surface of the substrate and level to obtain a treatment agent coating layer;

[0049] D2. Spraying a primer on the surface of the treatment agent coating, and leveling, curing to obtain the primer layer;

[0050] D3. NCVM electroplating on the surface of the primer layer to obtain the electroplated film layer;

[0051] D4. Spraying a midcoat on the surface of the midcoat layer, and leveling, curing to obtain the midcoat layer;

[0052] D5. Spraying a UV finishing varnish for vacuum plating on the surface of the midcoat layer, leveling, and light curing to obtain the finishing varnish layer.

[0053] In some embodiments of the present application, in step D1, the leveling temperature is 50-60℃.

[0054] In some embodiments of the present application, the leveling temperature is 53℃, 55℃ or 57℃.

[0055] In some embodiments of the present application, in step D1, the leveling time is 5-15 min.

[0056] In some embodiments of the present application, the leveling time is 6 min, 7 min, 8 min, 10 min or 12 min.

[0057] In some embodiments of the present application, in step D1, the material of the substrate comprises at least one of polycarbonate and acrylonitrile-butadiene-styrene plastic.

[0058] In some embodiments of the present application, in step D2, the leveling temperature is 50-60℃.

[0059] In some embodiments of the present application, in step D2, the leveling temperature is 53℃, 55℃ or 57℃.

[0060] In some embodiments of the present application, in step D2, the leveling time is 5-15 min.

[0061] In some embodiments of the present application, in step D2, the leveling time is 6 min, 8 min, 10 min or 12 min.

[0062] In some embodiments of the present application, in step D2, the curing mode comprises light curing.

[0063] In some embodiments of the present application, the light used for light curing has an energy of 700-900 mJ / cm 2 .

[0064] In some embodiments of the application, in step D3, the target material for the NCVM electroplating comprises indium.

[0065] In some embodiments of the application, in step D4, the temperature for the flow leveling is 50-60°C.

[0066] In some embodiments of the application, in step D4, the temperature for the flow leveling is 52°C, 55°C or 58°C.

[0067] In some embodiments of the application, in step D4, the duration for the flow leveling is 5-15 min.

[0068] In some embodiments of the application, in step D4, the duration for the flow leveling is 6 min, 8 min, 10 min or 12 min.

[0069] In some embodiments of the application, in step D4, the energy of the light used for the photo-curing is 800-1000 mJ / cm 2 .

[0070] In some embodiments of the application, in step D4, the energy of the light used for the photo-curing is 850 mJ / cm 2 , 900 mJ / cm 2 or 950 mJ / cm 2 .

[0071] According to some embodiments of the application, in step D5, the temperature for the flow leveling is 50-70°C.

[0072] According to some embodiments of the application, in step D5, the temperature for the flow leveling is 55°C, 60°C or 65°C.

[0073] According to some embodiments of the application, in step D5, the duration for the flow leveling is 5-15 min.

[0074] According to some embodiments of the application, in step D5, the duration for the flow leveling is 7 min, 10 min or 12 min.

[0075] According to some embodiments of the application, in step D5, the way of curing is photo-curing.

[0076] According to some embodiments of the application, in step D5, the energy of the light used for the photo-curing is 800-1000 mJ / cm 2 .

[0077] According to some embodiments of the application, in step D5, the energy of the light used for the photo-curing is 800 mJ / cm 2 , 900 mJ / cm 2 or 1000 mJ / cm2 .

[0078] In some embodiments of the present application, the composite coating further comprises a treatment agent coating layer disposed on the surface of the primer layer away from the electroplated film layer.

[0079] In some embodiments of the present application, the thickness of the treatment agent coating layer is 10-20 μm.

[0080] In some embodiments of the present application, the thickness of the treatment agent coating layer is 13 μm, 15 μm or 17 μm.

[0081] Unless otherwise specified, the thickness of the coating defined in the present application is the dry film thickness.

[0082] According to some embodiments of the present application, the thickness of the primer layer is 20-30 μm.

[0083] According to some embodiments of the present application, the thickness of the primer layer is 23 μm, 25 μm or 27 μm.

[0084] According to some embodiments of the present application, the thickness of the electroplated film layer is 20-30 nm.

[0085] According to some embodiments of the present application, the thickness of the primer layer is 23 nm, 25 nm or about 27 nm.

[0086] According to some embodiments of the present application, the material of the electroplated film layer comprises indium.

[0087] According to some embodiments of the present application, the thickness of the intermediate coating layer is 4-8 μm.

[0088] According to some embodiments of the present application, the thickness of the intermediate coating layer is 5 μm, 6 μm or 7 μm.

[0089] According to some embodiments of the present application, the thickness of the top coating layer is 6-10 μm.

[0090] According to some embodiments of the present application, the thickness of the top coating layer is 6 μm, 8 μm or 10 μm.

[0091] According to some embodiments of the present application, a method for disposing the composite coating is provided, which comprises spraying the UV wire drawing top coating for vacuum plating on the surface of the intermediate coating layer, followed by flow leveling and photocuring to obtain the top coating layer.

[0092] According to the four aspects of the present application, the composite coating is applied to the shell of an electronic product.

[0093] According to some embodiments of the present application, the electronic product comprises at least one of a smart phone, a notebook, a mobile camera and a smart wearable device.

[0094] In some embodiments of the present application, the paint film of the electronic product shell is not higher than 10 μm. DETAILED DESCRIPTION

[0095] The words "preferably", "more preferably" and the like used herein mean certain embodiments of the application which can provide certain benefits under certain circumstances. However, other embodiments can also be preferred or provide superior benefits under the same or other circumstances. Additionally, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude those other embodiments from the scope of the application.

[0096] When a numerical range is disclosed herein, the range is to be construed as continuous, and to include each and every value and sub-range within the range. Further, when a range is disclosed, the range is inclusive of the minimum and maximum values, and of each integer within the range. Further, when a plurality of ranges is provided, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood to be inclusive of all sub-ranges included therein.

[0097] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of the present application.

[0098] The reagents, methods and devices used in the present application are conventional reagents, methods and devices in the technical field, unless otherwise specified.

[0099] The sources of the raw materials used in the specific embodiments are as follows, unless otherwise specified:

[0100] The nano-modified UV polyurethane resin is UA-895 of Zhongshan Jiesida;

[0101] The nano-hybrid polyurethane resin is Lanke Lu L-6905B;

[0102] The polyurethane acrylic resin is 6196-100 of Changxing Chemical;

[0103] The aliphatic polyurethane resin is Zhenxin 266;

[0104] The dipentaerythritol hexaacrylate is DPHA from Changxing Chemical;

[0105] The acrylic polyurethane wax paste is BG-06 from Gifu, Japan;

[0106] The dispersant is BYK110 polymeric phosphate ester solution;

[0107] The leveling agent is BYK 333 polyether-modified polydimethylsiloxane;

[0108] The photoinitiator is Irgacure 184 and / or Darocur TPO from Jiuri Company;

[0109] The treating agent is PAP30737 from Songjing;

[0110] The primer is PEB10060 A from Songjing;

[0111] The midcoat is SP120-20013-1 from Songjing.

[0112] In order to further understand the working principle and effective technical effects of the present application, the following examples are used for illustration.

[0113] Example 1

[0114] In this example, a UV wire drawing finish for vacuum plating is prepared, and the preparation raw material ratio is shown in Table 1, and the specific steps are as follows:

[0115] S1. Preheat the polyurethane acrylic resin, nano-modified UV polyurethane resin, and nano-hybrid polyurethane resin to obtain a premix 1;

[0116] S2. Add the photoinitiator to part of the diluent to obtain a premix 2;

[0117] S3. Add the premix 2 to the premix 1 and mix;

[0118] S4. Add the dipentaerythritol hexaacrylate, dispersant, matting powder, acrylic polyurethane wax paste, leveling agent, and remaining diluent to step S3 and mix to obtain the UV wire drawing finish for vacuum plating.

[0119] Examples 2-6

[0120] Examples 2-6 each prepare a UV wire drawing finish for vacuum plating, and the difference from Example 1 is that the amount of some preparation raw materials is different, and the specific amount is shown in Table 1.

[0121] For the convenience of expression, the following two tables are used to express the ratio of the examples and the product performance, respectively, Table 1: weight parts table of each preparation raw material of UV wire drawing finish paint in examples; Table 2: performance test result table of UV wire drawing finish paint prepared based on the ratio of examples.

[0122] Comparative Example 1

[0123] This comparative example prepared a UV wire drawing finish paint for vacuum plating. The difference between this comparative example and Example 1 is that butyl acetate is used to replace di-pentaerythritol hexaacrylate in Example 1, and the rest of the conditions are the same.

[0124] Comparative Example 2

[0125] This comparative example prepared a UV wire drawing finish paint for vacuum plating. The difference between this comparative example and Example 1 is that polyurethane acrylic resin is used to replace nano-modified UV polyurethane resin and fluorocarbon-modified UV polyurethane resin in Example 1, and the rest of the conditions are the same.

[0126] Comparative Example 3

[0127] This comparative example prepared a UV wire drawing finish paint for vacuum plating. The difference between this comparative example and Example 1 is that silica matting powder is used to replace acrylic polyurethane wax paste in Example 1, and the rest of the conditions are the same.

[0128] Table 1. Weight parts table of each preparation raw material of UV wire drawing finish paint in examples

[0129]

[0130]

[0131] Test Example

[0132] This test example uses the UV wire drawing finish paint for vacuum plating obtained from the example as part of the raw material to prepare a composite coating for a mobile phone middle frame, and the specific process is as follows:

[0133] D1. The treatment agent is sprayed on the substrate (PC material) to a film thickness of 15 μm, and leveled at 60°C for 10 min to obtain a treatment agent coating layer loaded on the surface of the substrate;

[0134] D2. The primer is sprayed on the surface of the treatment agent coating layer to a film thickness of 30 μm, leveled at 60°C for 10 min, and cured with light with an arm length range of 200-450 nm and an energy of 800 mJ / cm 2 to obtain a primer layer;

[0135] D3. NCVM electroplating is performed on the primer layer, and the electroplating target material is indium to obtain an electroplating film layer with a thickness of 25 nm;

[0136] D4. Spray the midcoat on the electroplated film layer, the spray film thickness is 8 μm, level at 55 °C for 10 min; and cure with energy light, the wavelength range of the used light is 200-450 nm; obtain the midcoat layer; 2 photocure with energy light, the wavelength range of the used light is 200-450 nm; obtain the midcoat layer;

[0137] D5. Spray the UV wire drawing topcoat obtained in the example on the midcoat layer, the spray film thickness is 8 μm, level at 65 °C for 10 min; and photocure with energy light, the wavelength range of the used light is 200-450 nm; obtain the topcoat layer.

[0138] Table 2. Performance test results of the UV wire drawing topcoat prepared based on the ratio of the example

[0139]

[0140] In the example, the film thickness of the paint is controlled at 6-10 microns, and the specific indicators of the performance test include:

[0141] 1. The anti-graffiti test refers to drawing three 3 cm long marks on the paint film surface with ZEBRA (oil-based pen), and after 10 min, wiping with a dust-free cloth, no oil-based pen residue marks are considered as qualified.

[0142] 2. The steel wool test refers to testing 2000 times with 0000 steel wool under a weight of 1000 g, a stroke of 20 mm*20 mm, and a speed of 1 s / time, and then wiping the test site with a dust-free cloth soaked in alcohol, observing the scratch level of the test site surface, and the test sample gloss (transmittance for transparent pieces) before testing, and the change in the gloss value before and after the wear test should be less than 5% for qualified.

[0143] 3. The bending test refers to spraying the sample with the face outward, and bending 180 degrees on a cylindrical shaft of a certain diameter at the same position within 1-2 seconds, the cylindrical diameter is 20, 16, 14, 12, and 10 mm respectively, and the appearance of the paint film after bending is checked for no cracks for qualified.

[0144] 4. The haze test is to place the sample on the test table of the haze meter, and the instrument display reading is used as the judgment result to evaluate the anti-glare performance of the paint. The higher the haze value, the better the anti-glare effect, and a higher haze means that the material has stronger light scattering ability, which helps to reduce glare.

[0145] As can be seen from the comparison between Example 1 and Comparative Example 1, the addition of dipentaerythritol hexaacrylate significantly improves the curing speed.

[0146] Comparing Example 1 with Comparative Example 2, it can be seen that the addition of polyurethane acrylic resin to replace the nano-modified UV polyurethane resin and fluorocarbon-modified UV polyurethane resin in Example 1 significantly reduces the steel wool resistance and the anti-graffiti effect.

[0147] Comparing Example 1 with Comparative Example 3, it can be seen that the addition of silica matting powder to replace the acrylic polyurethane wax paste in Example 1 significantly reduces the anti-glare effect.

[0148] Comparing Example 1 with Example 2, it can be seen that the addition of aliphatic polyurethane resin significantly reduces the steel wool resistance and the anti-graffiti effect.

[0149] Comparing Example 1 with Example 7, it can be seen that the addition of mixed solvent significantly improves the film stability and water resistance.

[0150] Comparing Example 2 with Example 3, it can be seen that the acrylic polyurethane wax paste is significantly worse when it is less than 3%, and when it reaches 5%, the hand feeling is smooth and the anti-graffiti effect has no residue. Comparing Example 6, the hand feeling is obviously rough and the film has particles, and the gloss increases significantly after the steel wool test. The surface of the filler has a low friction coefficient, which forms a smooth touch on the material surface. The microstructure of the acrylic polyurethane wax paste is similar to the lotus effect in nature, with micron or nanometer level roughness, which can reduce the direct contact area and thus reduce friction. The filler is uniformly dispersed in the substrate, which can form a uniform coating on the material surface, improving the consistency and smoothness of the hand feeling.

[0151] Comparing Example 3 with Example 4 and Example 5, it can be seen that when the polyurethane acrylic resin reaches 20%, the film flexibility is significantly worse, and when the nano-modified UV polyurethane resin is less than 30%, the steel wool wear resistance and gloss increase significantly.

[0152] Therefore, it can be seen that the vacuum-coated UV wire coating has good steel wool and graffiti resistance, good anti-glare effect, fast curing speed of the topcoat, no need for additional baking before delivery, low energy consumption, high production efficiency, high film hardness, and high temperature and humidity resistance.

[0153] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Therefore, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present application, which does not deviate from the technical solution of the present application, shall fall within the protection scope of the technical solution of the present application.

Claims

1. A UV brushed topcoat for vacuum coating, characterized in that, The raw materials for preparation, by weight, include: 20-30 parts of fluorocarbon-modified UV polyurethane resin, wherein the fluorocarbon-modified UV polyurethane resin is Lankel L-6905B. 10-20 parts of polyurethane acrylic resin, wherein the polyurethane acrylic resin is Changxing Chemical's 6196-100. 20-30 parts of nano-modified UV polyurethane resin, wherein the nano-modified UV polyurethane resin is UA-895 from Zhongshan Jieshida. 5-8 parts of acrylic polyurethane wax paste, wherein the acrylic polyurethane wax paste is BG-06 from Gifu, Japan. The raw materials for preparing the UV brushed topcoat for vacuum coating also include a hexafunctional monomer, which includes dipentaerythritol hexaacrylate. The raw materials for preparing the UV brushed topcoat for vacuum coating also include additives, which include acrylic polyurethane wax paste, matting agent, photoinitiator, dispersant, diluent, and leveling agent. The diluent comprises: 9-12 parts of methyl isobutyl ketone, 8-12 parts of diacetone alcohol, and 9-15 parts of butyl acetate.

2. The UV brushed topcoat for vacuum coating according to claim 1, characterized in that, The leveling agent includes polyether-modified polydimethylsiloxane.

3. The method for preparing UV brushed topcoat for vacuum coating according to claim 1 or 2, characterized in that, include: The raw materials for preparing the UV brushed topcoat for vacuum coating are mixed and reacted.

4. A composite coating, characterized in that, The composite coating comprises a primer layer, an electroplated film layer, a middle coat layer, and a top coat layer that are stacked sequentially. The raw materials for preparing the topcoat layer include the UV brushing topcoat for vacuum coating as described in claim 1 or 2.

5. The application of the composite coating as described in claim 4 in the casing of an electronic product.

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