Environment-friendly water-based UV coating and preparation method thereof

Abstract

The invention relates to the field of coatings, in particular to an environment-friendly water-based UV coating and a preparation method thereof. Wherein the water-based UV coating is prepared from the following components in parts by weight: 40 to 80 parts of polyurethane acrylate, 10 to 30 parts of acrylic acid monomer, 5 to 15 parts of diphenylmethane modified methacrylate, 1 to 5 parts of filler, 0.1 to 2 parts of photoinitiator, 0.5 to 1.5 parts of dispersing agent, 0.1 to 0.5 part of defoaming agent, 0.1 to 1 part of flatting agent and 30 to 60 parts of water. The water-based UV coating prepared by the invention takes water as a main solvent, so that the emission of VOC (Volatile Organic Compounds) is remarkably reduced, and the development trend of green coatings is met. Through the synergistic effect of the urethane acrylate and the acrylic monomer, the use of a reactive diluent in a traditional UV coating is reduced, and the toxicity is further reduced. Meanwhile, the diphenylmethane modified methacrylate is better improved in the aspects of wear resistance, corrosion resistance, adhesive force and the like of the coating.

Description

Technical Field

[0001] The present invention relates to the field of coatings, and in particular to an environmentally friendly water-based UV coating and a preparation method thereof. Background Art

[0002] Water-based UV coatings have gradually replaced traditional coatings with their ultra-fast curing speed and excellent physical and chemical properties. Water-based UV coatings eliminate the toxicity and irritation of traditional coatings and are rapidly applied to bamboo and wood floors, furniture, glass, plastic, metal and other fields, becoming a new type of environmentally friendly material.

[0003] Water-based UV curing systems offer advantages such as being non-toxic, pollution-free, non-irritating, fast curing, excellent coating film properties, energy-saving, and safe production. However, existing water-based UV coatings have the following major drawbacks: First, because water-based coatings form a relatively thin film on the substrate surface, friction can cause the film to wear due to its insufficient hardness and toughness, leaving room for improvement in its wear resistance. Second, water-based UV coatings are currently primarily used in wood flooring and furniture, but rarely in exterior wall prefabricated panels. This is primarily because exterior wall prefabricated panels are typically used outdoors, where higher requirements are placed on the coating's corrosion resistance and adhesion. Therefore, there is a need to provide an environmentally friendly water-based UV coating that overcomes these drawbacks and expands its application areas. Summary of the Invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide an environmentally friendly water-based UV coating and a preparation method thereof.

[0005] The purpose of the present invention is achieved by adopting the following technical solutions:

[0006] In a first aspect, the present invention provides an environmentally friendly water-based UV coating, comprising, by weight:

[0007] 40-80 parts of polyurethane acrylate, 10-30 parts of acrylic monomer, 5-15 parts of diphenylmethane modified methacrylate, 1-5 parts of filler, 0.1-2 parts of photoinitiator, 0.5-1.5 parts of dispersant, 0.1-0.5 parts of defoaming agent, 0.1-1 parts of leveling agent, and 30-60 parts of water.

[0008] Preferably, the polyurethane acrylate is hexafunctional polyurethane acrylate, and the brand is Changxing Etercure 6145-100 or DSM AgiSyn 230A2.

[0009] Preferably, the acrylic monomer is one or a mixture of acrylic acid (AA), methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BA), 2-hydroxyethyl acrylate (HEA), methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), and 2-hydroxypropyl methacrylate (HPMA).

[0010] Preferably, the acrylic monomer is obtained by mixing methyl acrylate (MA), butyl acrylate (BA), methyl methacrylate (MMA), and 2-hydroxyethyl methacrylate (HEMA) in a mass ratio of 1 - 2:0.6 - 1.2:2 - 4:1.5 - 2.5.

[0011] Preferably, the filler is silane-activated nano-diatomaceous earth, and the preparation method includes:

[0012] Mix the nano-diatomaceous earth and an aqueous solution of ethanol and ultrasonically disperse them evenly. Dropwise add a silane coupling agent, reflux and stir for 2 - 4 h, then centrifuge, wash with water and dry to obtain silane-activated silica.

[0013] More preferably, the particle size of the nano-diatomaceous earth is 100 ± 10 nm, and the mass fraction of the aqueous solution of ethanol is 40% - 60%.

[0014] More preferably, the silane coupling agent is one or a mixture of KH-550, KH-560, and KH-571.

[0015] More preferably, the mass-volume ratio of nano-diatomaceous earth, silane coupling agent, and aqueous solution of ethanol is 1 g:(0.1 - 0.3) g:(10 - 20) mL.

[0016] Preferably, the photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) or hydroxycyclohexyl phenyl ketone (photoinitiator 184).

[0017] Preferably, the dispersant is one or a mixture of BYK-2013, BYK-190, BYK-192, and BYK-110. More preferably, it is BYK-2013.

[0018] Preferably, the defoamer is one or a mixture of Dow Corning DC-57, Dow Corning DC-51, and Degussa TEGO-825. More preferably, it is Dow Corning DC-57.

[0019] Preferably, the leveling agent is one or a mixture of TEGO-410, TEGO-440, and TEGO-432. More preferably, it is TEGO-410.

[0020] Preferably, the preparation method of the diphenylmethane-modified methacrylate includes:

[0021] Weigh glycidyl methacrylate (GMA) and 4,4'-diaminodiphenylmethane (MDA) and add them to an organic solvent. Dropwise add a catalyst, raise the temperature and stir for reaction treatment. After the reaction is completed, remove the solvent, purify and dry to obtain diphenylmethane-modified methacrylate.

[0022] Preferably, the mass-volume ratio of glycidyl methacrylate (GMA), 4,4'-diaminodiphenylmethane (MDA) and the organic solvent is (1.08 - 1.19) g: 0.75 g: (10 - 20) mL.

[0023] Preferably, the organic solvent is one of acetone, tetrahydrofuran, and N,N-dimethylformamide.

[0024] Preferably, the catalyst is triethylamine, and the addition amount is 1% - 3% of the mass of 4,4'-diaminodiphenylmethane.

[0025] Preferably, the process of raising the reaction temperature includes: first stir at 30 - 40 °C for 1 h, then raise the temperature to 50 - 60 °C and continue to stir for 2 - 5 h.

[0026] Preferably, the reaction stirring speed is 200 - 500 r / min.

[0027] Preferably, the purification is carried out using a dialysis bag with a molecular weight cut-off of 5000 - 8000 Da in pure water for 24 - 48 h.

[0028] In the second aspect, the present invention provides a preparation method of an environmentally friendly waterborne UV coating, including the following steps:

[0029] Step 1, weigh polyurethane acrylate, acrylic monomers, diphenylmethane-modified methacrylate, filler and dispersant and add them to deionized water, and disperse at a speed of 300 - 500 r / min for 20 - 30 min;

[0030] Step 2, then weigh a photoinitiator, an antifoaming agent and a leveling agent and add them to the mixture obtained in Step 1, and disperse at a speed of 200 - 400 r / min for 5 - 15 min to obtain the environmentally friendly waterborne UV coating.

[0031] The beneficial effects of the present invention are:

[0032] 1. The waterborne UV coating prepared by the present invention uses water as the main solvent, significantly reducing VOC emissions and conforming to the development trend of green coatings. Through the synergistic effect of polyurethane acrylate and acrylic monomers, the use of reactive diluents in traditional UV coatings is reduced, further reducing toxicity. At the same time, diphenylmethane-modified methacrylate has a good improvement in aspects such as the abrasion resistance, corrosion resistance, and adhesion of the coating.

[0033] 2. Diphenylmethane-modified methacrylate is prepared by using glycidyl methacrylate (GMA) and 4,4'-diaminodiphenylmethane (MDA) as raw materials and undergoing an epoxy-amine bonding reaction. Compared with directly adding GMA and MDA, in the present invention, GMA and MDA are first subjected to a bonding reaction, and the epoxy group of GMA reacts with the amino group of MDA to form a multiple crosslinked network, which has better high adhesiveness and curability, thereby further improving the abrasion resistance and adhesion of the material.

[0034] 3. The diphenylmethane structure introduced in diphenylmethane-modified methacrylate has good chemical stability and enhanced resistance to chemical erosion, so it can also enhance the corrosion resistance of the coating. Detailed Embodiments

[0035] The technical solutions of the present invention are illustrated below by specific examples. It should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combined steps or the insertion of other method steps between these clearly mentioned steps; it should also be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. Moreover, unless otherwise specified, the numbers of the method steps are only convenient tools for identifying the method steps, rather than limiting the arrangement order of the method steps or the scope in which the present invention can be implemented. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope in which the present invention can be implemented.

[0036] To better understand the above technical solutions, the exemplary embodiments of the present invention are described in more detail below. Although the exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0037] The present invention is further described below in conjunction with the following embodiments.

[0038] Example 1

[0039] An environment-friendly waterborne UV coating, by weight, includes:

[0040] 60 parts of polyurethane acrylate, 20 parts of acrylic monomer, 10 parts of diphenylmethane modified methacrylate, 3 parts of filler, 0.7 part of photoinitiator, 1 part of dispersant, 0.3 part of defoamer, 0.4 part of leveling agent, 45 parts of water.

[0041] Among them, the polyurethane acrylate is a hexafunctional polyurethane acrylate with the brand name Changxing Etercure 6145-100;

[0042] Among them, the acrylic monomer is a mixture of methyl acrylate (MA), butyl acrylate (BA), methyl methacrylate (MMA), and 2-hydroxyethyl methacrylate (HEMA) in a mass ratio of 1.5:0.9:3:2.

[0043] Among them, the filler is silane-activated nano-diatomite, and the preparation method includes:

[0044] Mix 1 g of nano-diatomite with a particle size of 100±10 nm and an aqueous solution of 15 mL of ethanol with a mass fraction of 50%, and ultrasonically disperse them evenly. Drop 0.2 g of silane coupling agent KH-550, reflux and stir for 3 h, then centrifuge, wash with water and dry to obtain silane-activated silica.

[0045] Among them, the photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO); the dispersant is BYK-2013; the defoamer is Dow Corning DC-57; the leveling agent is TEGO-410.

[0046] Among them, the preparation method of diphenylmethane modified methacrylate includes:

[0047] Weigh 1.14 g of glycidyl methacrylate (GMA) and 0.75 g of 4,4'-diaminodiphenylmethane (MDA), add them to 15 mL of acetone, dropwise add triethylamine as a catalyst, and the addition amount is 2% of the mass of 4,4'-diaminodiphenylmethane. First, stir at 35°C for 1 h, then raise the temperature to 55°C and continue to stir for 3 h. The stirring speed is 300 r / min. After the reaction is completed, rotary evaporate to remove the solvent, purify with a dialysis bag with a cut-off molecular weight of 7000 Da for 24 h, and vacuum dry to obtain diphenylmethane modified methacrylate.

[0048] The preparation method of the above-mentioned environment-friendly waterborne UV coating includes the following steps:

[0049] Step 1, weigh polyurethane acrylate, acrylic monomer, diphenylmethane modified methacrylate, filler and dispersant, add them to deionized water, and disperse at a speed of 400 r / min for 25 min;

[0050] Step 2: Weigh the photoinitiator, defoamer and leveling agent and add them into the mixture obtained in Step 1, disperse at a speed of 300 r / min for 10 min, and then an environmentally friendly waterborne UV coating is obtained.

[0051] Example 2

[0052] An environmentally friendly waterborne UV coating, by weight, comprises:

[0053] 40 parts of polyurethane acrylate, 10 parts of acrylic monomer, 5 parts of diphenylmethane modified methacrylate, 1 part of filler, 0.5 part of photoinitiator, 0.5 part of dispersant, 0.1 part of defoamer, 0.1 part of leveling agent, and 30 parts of water.

[0054] Among them, the polyurethane acrylate is a hexafunctional polyurethane acrylate with the brand name of DSM AgiSyn 230A-2.

[0055] Among them, the acrylic monomer is a mixture of methyl acrylate (MA), butyl acrylate (BA), methyl methacrylate (MMA), and 2-hydroxyethyl methacrylate (HEMA) in a mass ratio of 1:0.6:2:1.5.

[0056] Among them, the filler is silane-activated nano-diatomite, and the preparation method includes:

[0057] Mix 1 g of nano-diatomite with a particle size of 100±10 nm and an aqueous solution of 10 mL of ethanol with a mass fraction of 40%, ultrasonically disperse evenly, dropwise add 0.1 g of silane coupling agent KH-560, reflux and stir for 2 h, then centrifuge, wash with water and dry to obtain silane-activated silica.

[0058] Among them, the photoinitiator is hydroxycyclohexyl phenyl ketone (photoinitiator 184); the dispersant is BYK-190; the defoamer is Dow Corning DC-51; the leveling agent is TEGO-440.

[0059] Among them, the preparation method of diphenylmethane modified methacrylate includes:

[0060] Weigh 1.08 g of glycidyl methacrylate (GMA) and 0.75 g of 4,4'-diaminodiphenylmethane (MDA), add them into 10 mL of tetrahydrofuran, dropwise add a small amount of triethylamine as a catalyst, and the addition amount is 1% of the mass of 4,4'-diaminodiphenylmethane. First, stir at 30 °C for 1 h, then raise the temperature to 50 °C and continue to stir for 2 h. The stirring speed is 200 r / min. After the reaction is completed, rotary evaporate to remove the solvent, purify with a dialysis bag with a cut-off molecular weight of 7000 Da for 24 h, and vacuum dry to obtain diphenylmethane modified methacrylate.

[0061] The preparation method of the above-mentioned environment-friendly waterborne UV coating comprises the following steps:

[0062] Step 1: Weigh polyurethane acrylate, acrylic monomer, diphenylmethane-modified methacrylate, filler and dispersant, add them into deionized water, and disperse at a speed of 300 r / min for 30 min;

[0063] Step 2: Weigh photoinitiator, defoamer and leveling agent again and add them into the mixture obtained in Step 1, disperse at a speed of 200 r / min for 15 min, and then the environment-friendly waterborne UV coating is obtained.

[0064] Example 3

[0065] An environment-friendly waterborne UV coating, by weight, comprises:

[0066] 50 parts of polyurethane acrylate, 15 parts of acrylic monomer, 10 parts of diphenylmethane-modified methacrylate, 2 parts of filler, 1 part of photoinitiator, 1.2 parts of dispersant, 0.2 part of defoamer, 0.6 part of leveling agent, and 50 parts of water.

[0067] Among them, the polyurethane acrylate is a hexafunctional polyurethane acrylate with the brand name of Changxing Etercure 6145-100.

[0068] Among them, the acrylic monomer is obtained by mixing methyl acrylate (MA), butyl acrylate (BA), methyl methacrylate (MMA), and 2-hydroxyethyl methacrylate (HEMA) in a mass ratio of 1.2:0.7:2.5:2.

[0069] Among them, the filler is silane-activated nano-diatomite, and the preparation method comprises:

[0070] Mix 1 g of nano-diatomite with a particle size of 100±10 nm and an aqueous solution of 15 mL of ethanol with a mass fraction of 50%, disperse them evenly by ultrasonic wave, drop 0.2 g of silane coupling agent KH-560, reflux and stir for 3 h, then centrifuge, wash with water and dry to obtain silane-activated silica.

[0071] Among them, the photoinitiator is hydroxycyclohexyl phenyl ketone (photoinitiator 184); the dispersant is BYK-192; the defoamer is Dow Corning DC-51; the leveling agent is TEGO-410.

[0072] Among them, the preparation method of the diphenylmethane-modified methacrylate comprises:

[0073] Weigh 1.16 g of glycidyl methacrylate (GMA) and 0.75 g of 4,4'-diaminodiphenylmethane (MDA), add them to 16 mL of acetone, dropwise add triethylamine as a catalyst, and the addition amount is 1.5% of the mass of 4,4'-diaminodiphenylmethane. First, stir at 40 °C for 1 h, then raise the temperature to 55 °C and continue stirring for 4 h. The stirring speed is 200 r / min. After the reaction is completed, rotary evaporate to remove the solvent, purify with a dialysis bag with a molecular weight cut-off of 7000 Da for 24 h, and then vacuum dry to obtain diphenylmethane-modified methacrylate.

[0074] The preparation method of the above-mentioned environment-friendly waterborne UV coating includes the following steps:

[0075] Step 1, weigh polyurethane acrylate, acrylic monomer, diphenylmethane-modified methacrylate, filler and dispersant, add them to deionized water, and disperse at a speed of 400 r / min for 20 min;

[0076] Step 2, weigh photoinitiator, defoamer and leveling agent, add them to the mixed solution in Step 1, and disperse at a speed of 300 r / min for 15 min to obtain the environment-friendly waterborne UV coating.

[0077] Example 4

[0078] An environment-friendly waterborne UV coating, by weight, includes:

[0079] 80 parts of polyurethane acrylate, 30 parts of acrylic monomer, 15 parts of diphenylmethane-modified methacrylate, 5 parts of filler, 1.2 parts of photoinitiator, 1.5 parts of dispersant, 0.5 part of defoamer, 1 part of leveling agent, and 60 parts of water.

[0080] Among them, the polyurethane acrylate is a six-functional polyurethane acrylate with the brand name DSM AgiSyn 230A2.

[0081] Among them, the acrylic monomer is a mixture of methyl acrylate (MA), butyl acrylate (BA), methyl methacrylate (MMA), and 2-hydroxyethyl methacrylate (HEMA) in a mass ratio of 2:1.2:4:2.5.

[0082] Among them, the filler is silane-activated nano-diatomite, and the preparation method includes:

[0083] Mix 1 g of nano-diatomite with a particle size of 100 ± 10 nm and an aqueous solution of 20 mL of ethanol with a mass fraction of 60%, ultrasonically disperse evenly, dropwise add 0.3 g of silane coupling agent KH-571, reflux and stir for 4 h, then centrifuge, wash with water and dry to obtain silane-activated silica.

[0084] Among them, the photoinitiator is hydroxycyclohexane phenone (photoinitiator 184); the dispersant is BYK-110; the defoaming agent is TEGO-825; and the leveling agent is TEGO-432.

[0085] Wherein, the preparation method of diphenylmethane modified methacrylate comprises:

[0086] 1.08-1.19 g of 2,3-epoxypropyl methacrylate (GMA) and 0.75 g of 4,4'-diaminodiphenylmethane (MDA) were weighed and added to 10-20 mL of N,N-dimethylformamide. A small amount of triethylamine was added dropwise as a catalyst in an amount of 1%-3% of the mass of 4,4'-diaminodiphenylmethane. The mixture was stirred at 30-40° C. for 1 h, then heated to 50-60° C. and stirred for 2-5 h at a stirring speed of 200-500 r / min. After the reaction was completed, the solvent was removed by rotary evaporation, and the mixture was purified using a dialysis bag with a molecular weight cutoff of 7000 Da for 24-48 h. After vacuum drying, diphenylmethane-modified methacrylate was obtained.

[0087] The preparation method of the above-mentioned environmentally friendly water-based UV coating comprises the following steps:

[0088] Step 1: Weigh polyurethane acrylate, acrylic monomer, diphenylmethane-modified methacrylate, filler, and dispersant, add them to deionized water, and disperse at a speed of 500 r / min for 20 minutes;

[0089] In the second step, the photoinitiator, defoaming agent and leveling agent are weighed and added to the mixed solution in the first step, and dispersed at a speed of 400 r / min for 5 minutes to obtain an environmentally friendly water-based UV coating.

[0090] Comparative Example 1

[0091] An environmentally friendly water-based UV coating, comprising, by weight:

[0092] 70 parts of polyurethane acrylate, 20 parts of acrylic monomer, 3 parts of filler, 0.7 parts of photoinitiator, 1 part of dispersant, 0.3 parts of defoamer, 0.4 parts of leveling agent, and 45 parts of water.

[0093] The difference from Example 1 is that the diphenylmethane-modified methacrylate is replaced by an equal amount of polyurethane acrylate, and the other components and preparation process are the same as those in Example 1.

[0094] Comparative Example 2

[0095] An environmentally friendly water-based UV coating, comprising, by weight:

[0096] 60 parts of polyurethane acrylate, 20 parts of acrylic monomers, 10 parts of glycidyl methacrylate, 3 parts of filler, 0.7 parts of photoinitiator, 1 part of dispersant, 0.3 parts of defoamer, 0.4 parts of leveling agent, 45 parts of water.

[0097] The difference from Example 1 is that diphenylmethane-modified methacrylate is replaced with an equal amount of glycidyl methacrylate (GMA), and other components and the preparation process are the same as those in Example 1.

[0098] Comparative Example 3

[0099] An environmentally friendly waterborne UV coating, by weight, includes:

[0100] 60 parts of polyurethane acrylate, 20 parts of acrylic monomers, 6 parts of glycidyl methacrylate, 4 parts of 4,4'-diaminodiphenylmethane, 3 parts of filler, 0.7 parts of photoinitiator, 1 part of dispersant, 0.3 parts of defoamer, 0.4 parts of leveling agent, 45 parts of water.

[0101] The difference from Example 1 is that diphenylmethane-modified methacrylate is replaced by separately adding glycidyl methacrylate (GMA) and 4,4'-diaminodiphenylmethane (MDA), and other components and the preparation process are the same as those in Example 1.

[0102] Experimental Example

[0103] In order to more clearly illustrate the content of the present invention, the present invention has experimentally detected the performance of the waterborne UV coatings prepared in Example 1 and Comparative Examples 1-3, as follows:

[0104] Take 4 SPCC cold-rolled sheets of the same size, mark them respectively, and coat the waterborne UV coatings prepared in Example 1 and Comparative Examples 1-3 on the marked cold-rolled sheets by vacuum spraying, with a spraying thickness of 75 μm. After spraying, irradiate for 30 s under UV light with a radiation energy of 1000 mJ / cm 2 for curing, and then detect the performance after curing.

[0105] The detection items include:

[0106] The pencil hardness is detected with reference to GB / T 6739-2022 to test the scratch resistance of the coating;

[0107] The adhesion is detected with reference to GB / T 9286-2021. After scribing at a 1-mm interval and peeling off the tape, the peeling area is evaluated (0-5 levels, with 0 level being the best).

[0108] The abrasion resistance was detected with reference to ASTM D4060-19. Using a CS-10 grinding wheel, a load of 500 g, and measuring the mass loss after 1000 rotations.

[0109] The detection of alkali resistance and acid resistance was referred to GB / T 9274-1988. The alkali resistance test was to soak in 0.1mol / L NaOH solution for 72h, and the acid resistance test was to soak in 0.05mol / L H2SO4 solution for 72h. After drying, observe whether there are phenomena such as foaming and peeling.

[0110] The test results are shown in the following table:

[0111] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Hardness (pencil) 3H 2H 2H 3H Adhesion (grade) 0 1 1 1 Wear mass loss (mg) 17 42 33 25 Alkali resistance Basically intact Partially blistered Partially blistered Basically intact Acid resistance Basically intact Basically intact Basically intact Basically intact

[0112] It can be seen from the above tests that compared with the comparative example, the waterborne UV coating prepared in Example 1 of the present invention not only performs excellently in terms of hardness, alkali resistance and acid resistance, but also has better performance in adhesion and abrasion resistance.

[0113] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An environmentally friendly waterborne UV coating, characterized in that, By weight parts, it includes: 40 - 80 parts of polyurethane acrylate, 10 - 30 parts of acrylic monomer, 5 - 15 parts of diphenylmethane modified methacrylate, 1 - 5 parts of filler, 0.1 - 2 parts of photoinitiator, 0.5 - 1.5 parts of dispersant, 0.1 - 0.5 parts of defoamer, 0.1 - 1 part of leveling agent, and 30 - 60 parts of water.

2. An environmentally friendly waterborne UV coating according to claim 1, characterized in that, The polyurethane acrylate is a hexafunctional polyurethane acrylate, with the trade name of Changxing Etercure 6145 - 100 or DSM AgiSyn 230A2.

3. An environmentally friendly waterborne UV coating according to claim 1, characterized in that, The acrylic monomer is one or a mixture of acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2 - hydroxyethyl acrylate, methyl methacrylate, 2 - hydroxyethyl methacrylate, and 2 - hydroxypropyl methacrylate.

4. An environmentally friendly waterborne UV coating according to claim 1, characterized in that, The acrylic monomer is obtained by mixing methyl acrylate, butyl acrylate, methyl methacrylate, and 2 - hydroxyethyl methacrylate in a mass ratio of 1 - 2:0.6 - 1.2:2 - 4:1.5 - 2.

5.

5. An environment-friendly waterborne UV coating according to claim 1, characterized in that, The filler is silane - activated nano - diatomaceous earth, and the preparation method includes: Mix the nano - diatomaceous earth and an aqueous solution of ethanol and ultrasonically disperse them evenly. Dropwise add a silane coupling agent, reflux and stir for 2 - 4 h, then centrifuge, wash with water and dry to obtain silane - activated silica; wherein, the silane coupling agent is one or a mixture of KH - 550, KH - 560, and KH - 571, and the mass - to - volume ratio of nano - diatomaceous earth, silane coupling agent, and the aqueous solution of ethanol is 1 g:(0.1 - 0.3) g:(10 - 20) mL.

6. An environmentally friendly waterborne UV coating according to claim 1, characterized in that, The photoinitiator is 2,4,6 - trimethylbenzoyl - diphenylphosphine oxide or photoinitiator 184; the dispersant is one or a mixture of BYK - 2013, BYK - 190, BYK - 192, and BYK - 110; the defoamer is one or a mixture of Dow Corning DC - 57, Dow Corning DC - 51, and Degussa TEGO - 825; the leveling agent is one or a mixture of TEGO - 410, TEGO - 440, and TEGO - 432. More preferably, it is TEGO - 410.

7. An environmentally friendly waterborne UV coating according to claim 1, characterized in that, The preparation method of the diphenylmethane modified methacrylate includes: Weigh glycidyl methacrylate and 4,4'-diaminodiphenylmethane and add them into an organic solvent. Dropwise add a catalyst, raise the temperature and stir for reaction treatment. After the reaction ends, remove the solvent, purify and dry to obtain diphenylmethane modified methacrylate.

8. An environmentally friendly waterborne UV coating according to claim 7, characterized in that, The mass - to - volume ratio of glycidyl methacrylate, 4,4'-diaminodiphenylmethane, and the organic solvent is (1.08 - 1.19) g:0.75 g:(10 - 20) mL; the catalyst is triethylamine, and the addition amount is 1% - 3% of the mass of 4,4'-diaminodiphenylmethane.

9. An environmentally friendly waterborne UV coating according to claim 1, characterized in that, The process of raising the reaction temperature includes: first stir at a temperature of 30 - 40 °C for 1 h, then raise the temperature to 50 - 60 °C and continue to stir for 2 - 5 h.

10. A method for preparing the environment-friendly waterborne UV coating according to claim 1, characterized in that, It includes the following steps: Step 1, weigh polyurethane acrylate, acrylic monomer, diphenylmethane modified methacrylate, filler and dispersant, add them into deionized water, and disperse them at a speed of 300 - 500 r / min for 20 - 30 min; Step 2, weigh photoinitiator, defoamer and leveling agent, add them into the mixture obtained in Step 1, and disperse them at a speed of 200 - 400 r / min for 5 - 15 min to obtain an environmentally friendly waterborne UV coating.