Ultraviolet curing curtain coating bright white finish and preparation process thereof

Abstract

The invention discloses an ultraviolet curing curtain coating bright white finish and a preparation process thereof, and relates to the technical field of coatings, and the ultraviolet curing curtain coating bright white finish comprises the following components in parts by mass: 5-20% of polyurethane acrylate resin, 20-50% of modified epoxy acrylate resin, 15-30% of UV active monomer TPGDA, 0.2-1% of a wetting dispersant, 0.1-1% of a defoaming agent A, 0.1-1% of a defoaming agent B, 10-20% of titanium dioxide, and the balance of water. The coating is prepared from the following components in percentage by weight: 1 to 5 percent of white pigment, 2 to 7 percent of photoinitiator, 3 to 5 percent of anti-settling slurry, 0.1 to 1 percent of flatting agent C, 0.1 to 1 percent of flatting agent D and 10 to 20 percent of UV active monomer TMPTA. The ultraviolet curing curtain coating bright white finish has the advantages that the white finish is good in adhesive force, good in cutting property, good in mirror surface effect and high in gloss; meanwhile, the invention provides an oil absorption filter bag single-cylinder cycle manufacturing method, the stability of paint quality can be improved, and the construction defect problem and the paint film surface effect defect problem caused by substandard production environment or material quality can be reduced or solved.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, in particular to an ultraviolet light-cured pour-coated bright white topcoat and a preparation process thereof. Background Art

[0002] With the popularity of modern minimalist style, white gloss products have become a classic of modern fashion furniture. UV-cured glossy white surface is highly praised by some large panel manufacturers, panel furniture factories and high-end furniture customization factories because of its fast and efficient construction, solvent-free and environmentally friendly, and high fullness of paint film. However, users have high requirements for the surface effect of glossy white surface, and usually refer to the effect of mature spray PU glossy white surface that has been widely promoted and used. The titanium dioxide contained in UV glossy white surface paint will compete with the paint resin to absorb ultraviolet light, and the high coating amount of the spray paint will cause problems with the curing gradient of the paint. The paint may be cured in the shallow surface layer first and then in the deep layer. The paint flatness is poor at the microscopic level, and it is difficult to obtain a white paint film with a strong glaze texture, resulting in poor decorativeness and poor aesthetics of the paint film. Its decorative aesthetics cannot reach the effect of spray PU glossy white surface.

[0003] The coating amount of curtain coating is high, and the coating amount needs to be controlled at 110-140g / m 2 Although there is a certain market demand for UV curing spray coating glossy white surface, it currently has certain defects and limitations in technology. The main problems are poor construction stability, poor board surface effect, etc. There is basically no other UV spray coating glossy white surface paint on the market. The main problems are as follows:

[0004] 1. Poor defoaming performance during construction. Since the glossy white topcoat has no solvent, the construction viscosity is high and it is difficult to defoam. The paint contains a large amount of powder pigments and fillers such as titanium dioxide, which have poor defoaming performance. Adding dispersants to dispersed powders will affect the defoaming performance of the paint. Combining the above factors, the defoaming performance of the paint is poor, there are bubbles in the forest curtain, and bubbles are easily generated on the board surface.

[0005] 2. Poor shower curtain stability. Improper use of defoaming agent will cause shower curtain jumping, which will result in egg-like areas on the board without paint. This defect is not easy to rework, which seriously affects construction and use. Improper use of leveling agent will not only fail to solve the shower curtain stability caused by the above, but will affect the defoaming property.

[0006] 3. The glaze texture of the paint film is poor; there are basically no products related to UV-cured glossy white topcoat in the market. The UV-cured glossy white topcoat has a high coating volume, and titanium dioxide has a strong hiding power. The paint liquid curing gradient is inconsistent, resulting in poor glaze texture after the paint film is completely cured; the decorative aesthetics are not good enough, which affects market promotion. There are basically no other related products on the market;

[0007] 4. The whiteness of the paint film is not high enough; the resin is not matched and used properly, the paint is not white enough, and the paint film is not beautiful enough. Summary of the invention

[0008] The purpose of the present invention is to provide a UV-curing spray-coated glossy white topcoat and a preparation process thereof, aiming to solve the above-mentioned technical problems. The UV-curing spray-coated glossy white topcoat of the present invention provides a white topcoat with good adhesion, good cutting performance, good mirror effect and high gloss; at the same time, a single-cylinder circulation manufacturing method for an oil absorption filter bag is provided, which can improve the stability of the paint quality, and can reduce or solve the construction defects and paint film surface effect defects caused by the production environment or substandard material quality.

[0009] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0010] A UV-curable spray-coated bright white topcoat comprising the following components calculated by mass percentage:

[0011]

[0012] Preferably, the polyurethane acrylate resin adopts Nippon Paint Changrunfa's YTM601 resin; the modified epoxy acrylate resin adopts the water-washable XZ-02 resin of Hunan Xiangzhangshu New Material Technology Co., Ltd. The YTM601 resin of Nippon Paint Changrunfa is a hexafunctional aliphatic polyurethane resin with high crosslinking density, which is conducive to deep curing of the paint film and can improve the adhesion of the paint. At the same time, after the resin is cured, the paint film has a red phase, which can eliminate the yellow phase produced during the curing of the paint film and improve the whiteness of the paint film; the water-washable XZ-02 resin of Hunan Xiangzhangshu New Material Technology Co., Ltd. retains a hydroxyl group in the molecular structure of this resin, has good adhesion, and has good flexibility of the paint film, which is conducive to the release of shrinkage stress and the improvement of the adhesion of the paint film.

[0013] Preferably, the UV active monomer TPGDA is Nippon Paint's YTM6200; the wetting and dispersing agent is BYK's DISPERBYK-111. The UV active monomer TPGDA mainly adjusts the paint viscosity and can also participate in the curing and film formation; the wetting and dispersing agent is BYK's DISPERBYK-111, which mainly disperses white pigments such as titanium dioxide.

[0014] Preferably, the defoamer A is TEGO-920 defoamer produced by Evonik Degussa, and the defoamer B is MOUSSEX USF 2561 defoamer produced by Centronics. The amount of the defoamer A is 0.1%, and the amount of the defoamer B is 0.7%. The defoamer A is Evonik Degussa TEGO-920 defoamer, which has extremely strong anti-foaming and defoaming properties, but has poor solubility in the paint system, which easily causes fogging of the paint film. At the same time, it is easy to cause shrinkage holes in the paint film in the solvent-free spray coating system. At the same time, it is easy to jump the curtain during spray coating construction, and the paint film surface may also have mold spots and flowery phenomena, so its dosage needs to be strictly controlled; the defoamer B in the formula is the MOUSSEX USF 2561 defoamer of Pioneer Chemical, which does not affect the stability of spray coating even if it is added in a very high amount. On the contrary, it has a certain help to the stability of the paint spray curtain, and this defoamer does not affect the bright color of the paint film; the defoamer B is compounded with a small amount of strong defoamer A to obtain good defoaming and spray coating stability. As shown in Table 1:

[0015]

[0016]

[0017] Preferably, the titanium dioxide is BLR-895 titanium dioxide from Longman Billions; the white pigment is S-10 zinc sulfide from Hongzhi New Materials; the amount of the titanium dioxide is 10%, and the amount of the white pigment is 5%. The titanium dioxide is BLR-895 titanium dioxide from Longman Billions. This titanium dioxide is rutile titanium dioxide and is the main pigment in the formula, which mainly provides the hiding power and whiteness of the paint film; the white pigment is S-10 zinc sulfide from Hongzhi New Materials. The light-transmitting window of this special white pigment is quite different from that of titanium dioxide, which can provide a penetration window for ultraviolet light, improve the transmittance of ultraviolet light, make the curing gradient of the entire paint film consistent, and then make the paint film have a strong glaze texture after curing; the refractive index of this special white pigment is close to that of titanium dioxide, and is greatly different from that of resin and air. It has a hiding power close to that of titanium dioxide. Using a small amount to replace titanium dioxide does not affect the hiding power; this special white pigment has a certain blue phase, which can reduce the yellow-green value of the UV paint film, making the paint itself have a color-hanging and bleaching effect, and the paint film has a high whiteness. As shown in Table 2:

[0018] Titanium dioxide Special white pigment Titanium dioxide + special white pigment Dosage(%) 15 15 10+5 Fineness(μm) 20 20 20 Glaze texture generally Very strong Very strong Adhesion Level 2 Level 1 Level 1 Covering power powerful generally powerful

[0019] Preferably, the photoinitiator is a mixture of one or more of XBPO, TPO and MBF; the anti-settling slurry adopts CMU-H23 fumed silica anti-settling slurry produced by Nippon Paint Changrunfa. The photoinitiator contains XBPO, TPO and MBF, and mainly plays the role of photoinitiator. XBPO is JRCure-1109, TPO is JRCure-1108, and MBF is JRCure-1065; the anti-settling slurry is CMU-H23 fumed silica anti-settling slurry produced by Nippon Paint Changrunfa, and mainly plays the role of anti-settling.

[0020] Preferably, the leveling agent C is MODAREZ MF-A EX leveling agent produced by Centronics Chemicals, and the leveling agent D is Evonik Degussa Digo Rad 2100 leveling agent; the dosage of leveling agent C is 0.3%, and the dosage of leveling agent D is 0.03%. The leveling agent C is MODAREZ MF-A EX leveling agent from Centronics Chemicals. This leveling agent is an acrylic leveling agent containing reactive epoxy functional groups. It improves the leveling and fluidity of coatings and inks in non-aqueous systems. Due to its good compatibility, it is particularly suitable for varnishes. It can improve leveling and fluidity without causing any haze and yellowing, and does not produce the side effect of stabilizing bubbles. At the same time, it can improve the stability of the shower curtain; the leveling agent D is Evonik Degussa Digo Rad2100 leveling agent, this leveling agent is an organic silicon leveling agent with extremely strong fluidity and good substrate wettability, which can significantly reduce and improve the surface tension of the liquid, has good anti-skipping curtain performance, can significantly improve the stability of the curtain and strong anti-shrinkage cratering performance. The optimized combination of leveling agents C and D can well balance the construction performance of the paint such as anti-skipping curtain, anti-shrinkage cratering, leveling and whether it has stable foaming; a very small amount of organic silicon leveling agent D can improve the surface tension of the paint liquid, and produce a synergistic effect with acrylic leveling agent A, significantly improve the anti-shrinkage cratering and anti-skipping curtain of the paint, and finally obtain a very stable curtain, as shown in Table 3:

[0021]

[0022]

[0023] Preferably, the UV active monomer TMPTA is Nippon Paint Long Runfa's YTM6200; the UV active monomer TMPTA mainly plays a role in adjusting viscosity and can also participate in film formation and increase hardness and crosslinking density.

[0024] A preparation process of a UV-curing curtain coating glossy white topcoat, which is applied to any of the UV-curing curtain coating glossy white topcoats described above, comprises the following steps:

[0025] S1: Select the paint tank, make sure the inner wall of the tank has been cleaned and the discharge valve is closed;

[0026] S2: Add polyurethane acrylate resin, modified epoxy acrylate resin and UV active monomer TPGDA into the paint tank in sequence, and disperse them for 5-10 minutes at a medium speed in a disperser, wherein the speed of the medium speed dispersion in the disperser is 1000±200 rpm;

[0027] S3: Add a wetting dispersant, a defoamer A and a defoamer B in sequence under low-speed stirring, and disperse for 5-10 minutes at a medium speed in a disperser, wherein the speed of the medium-speed dispersion in the disperser is 1000±200 rpm;

[0028] S4: titanium dioxide, white pigment and photoinitiator are added in sequence under low-speed stirring, and dispersed at high speed for 20-30 minutes in a disperser to make the paint fineness less than 20um. The speed of the disperser at high speed is 1500±200 rpm;

[0029] S5: Add anti-settling slurry, leveling agent C, leveling agent D and UV active monomer TMPTA in sequence, and disperse for 5-10 minutes at a medium speed in a disperser, wherein the speed of the medium speed dispersion in the disperser is 1000±200 rpm;

[0030] S6: Use an air pump to transport the white paint in step S5 in the paint tank to the oil absorption filter bag for filtration. The filtered paint flows back to the paint tank through the pipeline and is repeatedly filtered again. The cycle filtration time is 2-8 hours.

[0031] S7: The white paint that has completed the oil absorption filter bag single cylinder circulation filtration process in step S6 is determined as the finished paint, and an appropriate amount of the finished paint is randomly taken out for testing, and other finished paints are packaged;

[0032] S8: The paint and paint film that have completed the test in step S7 shall be evaluated according to HG / T 3655-2012.

[0033] Preferably, in the test of step S7, the following steps are included: white melamine board → sanding → roller coating of UV adhesion primer, with a coating amount of 15-20 g / m 2 → UV mercury lamp curing semi-dry, mercury lamp energy 250-350mJ / cm 2 →Roller-coat UV white primer, application amount 18-25g / m 2 → UV lamp curing semi-dry, lamp energy 200-300mJ / cm 2 →Roller-coat UV white primer, application amount 18-25g / m 2 → UV lamp curing semi-dry, lamp energy 200-300mJ / cm 2 →Roller-coat UV white primer, application amount 18-25g / m 2→ UV lamp curing semi-dry, lamp energy 200-300mJ / cm 2 →Roller coating of UV yellowing resistant transparent sanding primer, coating amount 38-45g / m 2 → UV mercury lamp curing, full dry, mercury lamp energy 250-350mJ / cm 2 → 400#+600# sandpaper sanding → dust removal → roller coating UV pre-drying roller coating paint, construction coating amount 5-7g / m 2 → UV coating of bright white topcoat, application amount 110-120g / m 2 → 30℃ infrared leveling 30S → UV lamp curing, fully dry, lamp energy 500-600mJ / cm 2 , and then test various properties after the board temperature drops to room temperature.

[0034] The UV-curable spray-coated bright white topcoat and its preparation process have the following beneficial effects:

[0035] 1. Solve the problem of poor glaze texture of UV coating bright white topcoat; by selecting and matching titanium dioxide and other white pigments, increasing the UV light transmission window of the filler, and improving the curing gradient of the paint liquid, this can not only solve the problem of glaze texture of the paint film, but also improve the problem of paint film adhesion;

[0036] 2. Solve the problem of poor paint construction performance; paint construction performance mainly includes defoaming and curtain stability. The construction performance problem can be solved by optimizing the combination of defoaming agent and flow agent;

[0037] 3. Solve the problem of quality stability between paint batches; through the innovative use of oil absorption filter bag single cylinder circulation process, harmful materials such as foreign oil pollution, additives that are not fully dissolved and dispersed evenly, impurities, etc. in the paint can be absorbed to improve the construction stability of the paint;

[0038] 4. Solve the problem of paint film whiteness; by screening resins, pigments, fillers and initiators, a high white value pouring glossy white topcoat can be obtained. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the technical solution of the present invention, the product of the present invention is further described in detail below in conjunction with embodiments.

[0040] It should be noted that all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0041] The present invention is further described below in conjunction with examples. It should be understood that the examples are only used to illustrate the present invention rather than to limit the scope of the present invention.

[0042] A UV-curable spray-coated bright white topcoat comprising the following components calculated by mass percentage:

[0043]

[0044] The resin used in the present invention is Nippon Paint Changrunfa's Yatumei YTM601 resin, and the paint film has a red phase after curing, which is very conducive to use in white paint; the water-washed XZ-02 resin used by Xiangzhangshu New Material Technology Co., Ltd. not only has good initial yellowing and yellowing resistance, but also retains a hydroxyl group in the resin molecular structure, and has good adhesion. The combination of the two resins can significantly improve the whiteness of the paint while also having good adhesion; the white pigment used is zinc sulfide white pigment, which is different from the light-transmitting window of rutile titanium dioxide. When used in combination with titanium dioxide, it can improve the ultraviolet transmittance of white paint, change the paint film curing gradient and the deep curing performance of the paint film, and obtain a paint film with good adhesion and strong glaze texture. This zinc sulfide white pigment is not limited to Hongzhi New Material S-10 zinc sulfide, and other companies' zinc sulfide white pigments also have similar effects and functions. The key to using Evonik Degussa Digo's TEGO-920 defoamer is to use MOUSSEX USF of Pioneer Chemical in combination. 2561 defoamer, this defoamer not only has a certain defoaming property in the coating, but also helps to stabilize the coating curtain to a certain extent, and has no negative impact on the brightness of the paint film; a large amount of MODAREZ MF-A EX leveling agent from Pioneer Chemical is used. This leveling agent does not stabilize the foam but can stabilize the coating curtain and is of great help to the stability of the coating curtain. Its disadvantage is that the anti-shrinkage property is slightly poor. In order to solve the anti-shrinkage property and further improve the stability of the coating curtain, Evonik Degussa high Rad 2100 leveling agent.

[0045] According to the weight proportions in the above table, a preparation process of a UV-curable curtain coating bright white topcoat is adopted for preparation, comprising the following steps:

[0046] S1: Select the paint tank, make sure the inner wall of the tank has been cleaned and the discharge valve is closed;

[0047] S2: Add polyurethane acrylate resin, modified epoxy acrylate resin and UV active monomer TPGDA into the paint tank in sequence, and disperse them for 5-10 minutes at a medium speed in a disperser, wherein the speed of the medium speed dispersion in the disperser is 1000±200 rpm;

[0048] S3: Add a wetting dispersant, a defoamer A and a defoamer B in sequence under low-speed stirring, and disperse for 5-10 minutes at a medium speed in a disperser, wherein the speed of the medium-speed dispersion in the disperser is 1000±200 rpm;

[0049] S4: titanium dioxide, white pigment and photoinitiator are added in sequence under low-speed stirring, and dispersed at high speed for 20-30 minutes in a disperser to make the paint fineness less than 20um. The speed of the disperser at high speed is 1500±200 rpm;

[0050] S5: Add anti-settling slurry, leveling agent C, leveling agent D and UV active monomer TMPTA in sequence, and disperse for 5-10 minutes at a medium speed in a disperser, wherein the speed of the medium speed dispersion in the disperser is 1000±200 rpm;

[0051] S6: Use an air pump to transport the white paint in step S5 in the paint tank to the oil absorption filter bag for filtration. The filtered paint flows back to the paint tank through the pipeline and is repeatedly filtered again. The cycle filtration time is 2-8 hours.

[0052] S7: The white paint that has completed the oil absorption filter bag single cylinder circulation filtration process in step S6 is defined as the finished paint, and a proper amount of the finished paint is randomly taken out for testing, and other finished paints are packaged; the test includes the following steps: white melamine board → sanding → roller coating UV adhesion primer, the construction coating amount is 15-20g / m 2 → UV mercury lamp curing semi-dry, mercury lamp energy 250-350mJ / cm 2 →Roller-coat UV white primer, application amount 18-25g / m 2 → UV lamp curing semi-dry, lamp energy 200-300mJ / cm 2 →Roller-coat UV white primer, application amount 18-25g / m 2 → UV lamp curing semi-dry, lamp energy 200-300mJ / cm 2 →Roller-coat UV white primer, application amount 18-25g / m 2 → UV lamp curing semi-dry, lamp energy 200-300mJ / cm 2 →Roller coating of UV yellowing resistant transparent sanding primer, coating amount 38-45g / m 2 → UV mercury lamp curing, full dry, mercury lamp energy 250-350mJ / cm 2 → 400#+600# sandpaper sanding → dust removal → roller coating UV pre-drying roller coating paint, construction coating amount 5-7g / m 2 → UV coating of bright white topcoat, application amount 110-120g / m 2 → 30℃ infrared leveling 30S → UV gallium lamp curing, full dry, gallium lamp energy 500-600mJ / cm2 , after the board temperature drops to room temperature, test various properties;

[0053] S8: The paint and paint film that have completed the test in step S7 shall be evaluated according to HG / T 3655-2012.

[0054] A preparation process for UV-curing glossy white topcoat provided by the technical solution of the present invention is a production process using an oil-absorbing filter bag single-cylinder circulation. The oil-absorbing filter bag single-cylinder circulation process refers to using an air pump to transport the paint to be inspected in the paint tank that has been fully fed and dispersed into the oil-absorbing filter bag. The oil-absorbing filter bag is fixed in a metal container and filtered by continuously inputting paint pressure. The filtered paint flows back to the paint tank through a pipe at the end of the metal container, and the cycle is repeated. The key to this oil-absorbing filter bag single-cylinder circulation process is to use an oil-absorbing filter bag and require a certain cycle time. The cycle time is controlled at 2-8 hours. The specific duration needs to be determined according to the weight of the paint, and 4 to 8 hours is the best time.

[0055] At present, the spray coating glossy white topcoat produced by ordinary conventional processes has a 30% failure rate in terms of curtain stability and plate surface shrinkage due to the instability of the production environment, differences between raw material batches, and differences in the front end, process, and back end of paint production. After analysis and research, the oil absorption filter bag single cylinder circulation process was adopted for production, which significantly reduced the failure rate. After a period of observation, the failure rate can be controlled within 2%, as shown in Table 4:

[0056] Process of the present invention General Process Paint batch quality complaint rate Paint batch complaints of shrinkage or curtain jumping are around 2% The paint batch complaint rate is about 30%

[0057] The technical solution of the present invention provides a single-cylinder circulation production process of an oil-absorbing filter bag for UV-curing glossy white topcoat, which is not only suitable for glossy white topcoat, but also for all spray paints, and even more suitable for all paints. The filter bag in the single-cylinder circulation process of the oil-absorbing filter bag can absorb harmful materials such as foreign oil stains, additives that are not fully dissolved and dispersed, and impurities in the paint, thereby improving the construction stability of the paint. Even if the pollutants introduced by the process links such as resin, monomer, or feeding and dispersion are not properly controlled, they can be absorbed by the oil-absorbing filter bag, thereby providing guarantee for the quality of the paint.

[0058] Comparative Examples 1-6 with different resin ratios and corresponding performance results:

[0059]

[0060] It can be seen from the test results in the above table that Example 1 has poor cutting performance with chipped edges of the saw board, Examples 2 and 3 have poor paint film effects with shrinkage holes in the paint film, and Example 2 also has poor defoaming performance with bubbles in the shower curtain, Examples 4 and 5 have poor paint film effects with mildew spots on the paint film, and have a small amount of shower curtain bubbles, while Example 6 has no other defects and is the best ratio among the six examples.

[0061] The preparation process of the UV-curable curtain coating bright white topcoat of the present invention has the following advantages:

[0062]

[0063]

[0064] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in the industry can smoothly implement the present invention as shown in the specification and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with the profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention still belong to the present invention.

Claims

1. A UV-curing glossy white topcoat, characterized in that: Includes the following components calculated by mass percentage:

2. The UV-curable curtain coating bright white topcoat according to claim 1, characterized in that: The polyurethane acrylate resin adopts Nippon Paint Changrunfa's YTM7601 resin; the modified epoxy acrylate resin adopts the water-washable XZ-02 resin of Hunan Xiangzhangshu New Material Technology Co., Ltd.

3. The UV-curable curtain coating bright white topcoat according to claim 1, characterized in that: The UV active monomer TPGDA is Nippon Paint's YTM6200; the wetting and dispersing agent is BYK's DISPERBYK-111.

4. The UV-curable curtain coating bright white topcoat according to claim 1, characterized in that: The defoamer A is TEGO-920 defoamer produced by Evonik Degussa, and the defoamer B is MOUSSEX USF 2561 defoamer produced by Centronics. The dosage of the defoamer A is 0.1%, and the dosage of the defoamer B is 0.7%.

5. The UV-curable curtain coating bright white topcoat according to claim 1, characterized in that: The titanium dioxide is BLR-895 titanium dioxide produced by Lomon Billions; the white pigment is S-10 zinc sulfide produced by Hongzhi New Materials; the amount of the titanium dioxide is 10%, and the amount of the white pigment is 5%.

6. The UV-curable curtain coating bright white topcoat according to claim 1, characterized in that: The photoinitiator is a mixture of one or more of XBPO, TPO and MBF; the anti-settling slurry adopts CMU-H23 fumed silica anti-settling slurry produced by Nippon Paint.

7. The UV-curable curtain coating bright white topcoat according to claim 1, characterized in that: The leveling agent C is MODAREZ MF-A EX leveling agent produced by Centronics Chemicals, and the leveling agent D is Evonik Degussa Digo Rad2100 leveling agent; the dosage of the leveling agent C is 0.3%, and the dosage of the leveling agent D is 0.03%.

8. The UV-curable curtain coating bright white topcoat according to claim 1, characterized in that: The UV active monomer TMPTA is Nippon Paint's YTM6200.

9. A process for preparing a UV-curable curtain coating bright white topcoat, characterized in that: The UV-curable curtain coating bright white topcoat as described in any one of claims 1 to 8 comprises the following steps: S1: Select the paint tank, make sure the inner wall of the tank has been cleaned and the discharge valve is closed; S2: Add polyurethane acrylate resin, modified epoxy acrylate resin and UV active monomer TPGDA into the paint tank in sequence, and disperse them for 5-10 minutes at a medium speed in a disperser, wherein the speed of the medium speed dispersion in the disperser is 1000±200 rpm; S3: Add a wetting dispersant, a defoamer A and a defoamer B in sequence under low-speed stirring, and disperse for 5-10 minutes at a medium speed in a disperser, wherein the speed of the medium-speed dispersion in the disperser is 1000±200 rpm; S4: titanium dioxide, white pigment and photoinitiator are added in sequence under low-speed stirring, and dispersed at high speed for 20-30 minutes in a disperser to make the paint fineness less than 20um. The speed of the disperser at high speed is 1500±200 rpm; S5: Add anti-settling slurry, leveling agent C, leveling agent D and UV active monomer TMPTA in sequence, and disperse for 5-10 minutes at a medium speed in a disperser, wherein the speed of the medium speed dispersion in the disperser is 1000±200 rpm; S6: Use an air pump to transport the white paint in step S5 in the paint tank to the oil absorption filter bag for filtration. The filtered paint flows back to the paint tank through the pipeline and is repeatedly filtered again. The cycle filtration time is 2-8 hours. S7: The white paint that has completed the oil absorption filter bag single cylinder circulation filtration process in step S6 is determined as the finished paint, and an appropriate amount of the finished paint is randomly taken out for testing, and other finished paints are packaged; S8: The paint and paint film that have completed the test in step S7 shall be evaluated according to HG / T 3655-2012.

10. The process for preparing the UV-curable curtain coating bright white topcoat according to claim 9, characterized in that: In the test of step S7, the following steps are included: white melamine board → sanding → roller coating of UV adhesion primer, with a coating amount of 15-20g / m 2 → UV mercury lamp curing semi-dry, mercury lamp energy 250-350mJ / cm 2 →Roller-coat UV white primer, application amount 18-25g / m 2 → UV lamp curing semi-dry, lamp energy 200-300mJ / cm 2 →Roller-coat UV white primer, application amount 18-25g / m 2 → UV lamp curing semi-dry, lamp energy 200-300mJ / cm 2 →Roller-coat UV white primer, application amount 18-25g / m 2 → UV lamp curing semi-dry, lamp energy 200-300mJ / cm 2 →Roller coating of UV yellowing resistant transparent sanding primer, coating amount 38-45g / m 2 → UV mercury lamp curing, full dry, mercury lamp energy 250-350mJ / cm 2 → 400#+600# sandpaper sanding → dust removal → roller coating UV pre-drying roller coating paint, construction coating amount 5-7g / m 2 → UV coating of bright white topcoat, application amount 110-120g / m 2 → 30℃ infrared leveling 30S → UV lamp curing, fully dry, lamp energy 500-600mJ / cm 2 , and then test various properties after the board temperature drops to room temperature.

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