阅读说明：本技术 UV-Monocoat用水性UV树脂及其制备方法 (Water-based UV resin for UV-Monocoat and preparation method thereof ) 是由 许钧强 齐俊胜 于 2021-08-19 设计创作，主要内容包括：本发明涉及一种UV-Monocoat用水性UV树脂及其制备方法,水性UV树脂为磺酸盐阴离子型聚氨酯改性丙烯酸酯,含8个活性官能基团；本发明的水性UV树脂可与铝银浆、透明色浆、消光剂、光引发剂、助剂和水配制成水性UV-Monocoat；其漆膜具有优异的附着力、耐磨性、耐醇性、耐水煮性、柔韧性、抗划伤性、耐手汗性、耐高温高湿、耐污染性、耐老化、抗粘连性和肤感性,涂膜金属感强,不影响重涂性,安全环保。可用于笔电、手机、鼠标、按键、家电、开关、包装材料、汽车内饰件等塑胶基材如ABS、PC、PET、ABS+PC、ABS+玻纤、PC+玻纤等表面上的一涂,也可在各种金属合金基材底漆或粉未底漆上的面涂。(The invention relates to a water-based UV resin for UV-Monocoat and a preparation method thereof, wherein the water-based UV resin is sulfonate anion type polyurethane modified acrylate and contains 8 active functional groups; the waterborne UV resin can be prepared into waterborne UV-Monocoat with aluminum paste, transparent color paste, a delustering agent, a photoinitiator, an auxiliary agent and water; the paint film has excellent adhesive force, wear resistance, alcohol resistance, boiling resistance, flexibility, scratch resistance, hand perspiration resistance, high temperature and high humidity resistance, pollution resistance, aging resistance, blocking resistance and skin feel, has strong metal feel of the paint film, does not influence recoatability, and is safe and environment-friendly. The coating can be used for one-time coating on the surfaces of plastic base materials such as ABS, PC, PET, ABS + PC, ABS + glass fiber, PC + glass fiber and the like, such as pen power, mobile phones, mice, keys, household appliances, switches, packaging materials, automotive upholstery and the like, and can also be coated on the surfaces of various metal alloy base material primers or powder primers.)

1. The water-based UV resin for the UV-Monocoat is characterized by comprising the following components in percentage by weight: 35.0-40.0% of water-based UV polymer, 3.0-6.0% of ethoxylated trimethylolpropane triacrylate, 0.3-0.5% of fatty alcohol-polyoxyethylene ether and 55.0-60.0% of deionized water;

the water-based UV polymer has a branched structure, contains 8 active functional groups, and has a molecular structural formula shown as the following formula:

in the formula, R is

The R is₁Is H or CH₃；

The preparation steps of the waterborne UV polymer are as follows:

a) preparing epoxy acrylate EA: adding epoxy resin into a four-neck flask provided with a reflux condenser pipe, a thermometer, a dropping funnel and a stirrer, slowly dropping a mixture consisting of a carboxyl acrylic monomer, a catalyst and p-hydroxyanisole when the temperature rises to 80 ℃, slowly heating to 85-90 ℃ after dropping, carrying out heat preservation reaction for 2.5-4 h, then sampling every 30min to detect the acid value of the system, and stopping the reaction when the detected acid value is lower than 5mgKOH/g to prepare epoxy acrylate EA;

b) preparing a polyurethane prepolymer: adding pre-dehydrated polyether glycol sulfonate, polyester glycol, diisocyanate and dibutyltin dilaurate into a four-neck flask provided with a reflux condenser tube, a thermometer, a dropping funnel and a stirrer, stirring and heating, controlling the reaction at 80-90 ℃ for 1.5-2 h, sampling and detecting the NCO value of a system, and cooling to 65 ℃ when the detected NCO value reaches a specified theoretical value to prepare a sulfonate-containing polyurethane prepolymer WPU-1; adding a polymerization inhibitor, then adding dimethylolpropionic acid DMPA (dimethyl formamide) which is subjected to drying treatment in advance, heating to 80-90 ℃, continuing to react for 1.5-2 h, sampling to detect the NCO value of a system, cooling to 50 ℃ when the detected NCO value reaches a specified theoretical value, adding acetone accounting for 8.0-10.0% of the total material amount for dilution, and preparing a polyurethane prepolymer WPU-2 containing a hydrophilic group;

c) preparation of UV curable polyurethane prepolymer: heating to 65 ℃ in the WPU-2 prepolymer, beginning to drop metered pentaerythritol triacrylate, dropping within 1-2 h, heating to 70-75 ℃ after the dropping is finished, continuing to react until the detected NCO value reaches half of that of the polyurethane prepolymer, stopping the reaction, and cooling to 40 ℃ to obtain a UV-curable polyurethane prepolymer WPU-PETA;

d) preparing a UV-curable epoxy modified polyurethane prepolymer: adding 3.0-5.0% of acetone into WPU-PETA to adjust the viscosity of the system to a proper value, adding metered EA while stirring, heating to 65-70 ℃, reacting for 1-2.0 h, sampling and detecting the NCO value of the system, cooling to 40 ℃ when the detected NCO value is constant, and stopping the reaction to prepare UV-curable epoxy modified polyurethane prepolymer EA-WPU-PETA;

e) preparation of aqueous UV polymer dispersion: adding metered triethylamine and deionized water into the EA-WPU-PETA prepolymer, quickly stirring for 30min, heating to 40 ℃, and distilling under reduced pressure to remove acetone to obtain a water-based UV polymer dispersion;

f) preparation of a UV-Monocoat aqueous UV resin: adding ethoxylated trimethylolpropane triacrylate and fatty alcohol-polyoxyethylene ether into the aqueous UV polymer dispersion, quickly stirring for 30min, standing, filtering and packaging to obtain the UV-Monocoat aqueous UV resin;

wherein the diisocyanate is one of isophorone diisocyanate (IPDI) or dicyclohexylmethane diisocyanate (HMDI);

the polyester dihydric alcohol is one of poly neopentyl glycol adipate PNA or poly trimethylolpropane adipate PTA, and the molecular weight of the polyester dihydric alcohol is M_n＝1000；

In the step a), the molar ratio of the epoxy resin to the carboxyl-containing acrylic monomer is 1: 2; the addition amount of the catalyst is 1.5-2.5% of the total amount of reactants; the addition amount of the p-hydroxyanisole is 0.1-0.5% of the total amount of reactants;

in step b), the molar ratio of the diisocyanate to the polyglycol is NCO: OH is 3.5-3.8: 1; the molar ratio of the polyether glycol sulfonate to the polyester glycol is 1:1 to 1.2; the addition amount of the dimethylolpropionic acid is 6.0-8.0% of the total feeding amount; the addition amount of the dibutyltin dilaurate is 0.03-0.05% of the amount of diisocyanate; the addition amount of the polymerization inhibitor is 0.04-0.06% of the total feeding amount; the content of the hydrophilic group is 15.0-25.0 mmol per hundred grams of WPU-2 prepolymer, and the molar ratio of the sulfonate to the carboxylate is 2: 1;

in the step c), the mol ratio of the WPU-2 to the pentaerythritol triacrylate is NCO: PETA is 2.0-2.2: 1;

in the step d), the molar ratio of EA to WPU-PETA is OH: NCO is 3.0-3.3: 2, and the addition amount of EA is 25.0-55.0% of the total amount of EA-WPU-PETA prepolymer;

in the step e), the molar ratio of triethylamine to dimethylolpropionic acid is 1-1.02: 1; the addition amount of the deionized water is 55.0-60.0% of the total amount of the aqueous UV dispersoid.

2. The waterborne UV resin of claim 1, wherein the epoxy resin is one of bisphenol A epoxy resin E-44 or bisphenol A epoxy resin E-51.

3. The waterborne UV resin of claim 1, wherein the carboxyl group containing acrylic monomer is one of acrylic acid or methacrylic acid.

4. The waterborne UV resin of claim 1, wherein the catalyst is at least one of N, N-dimethylaniline, tetrabutylammonium bromide, N-dimethylethanolamine, N-dimethylformamide and triphenylphosphine.

5. The waterborne UV resin of claim 1, wherein the catalyst is one of a mixture of N, N-dimethylaniline and tetrabutylammonium bromide in a mass ratio of 1:1 or a mixture of N, N-dimethylethanolamine and N, N-dimethylformamide in a mass ratio of 1: 1.

6. The waterborne UV resin of claim 1, wherein the polymerization inhibitor is one of 2,2,6, 6-tetramethylpiperidine nitroxide radical HTEMPO or hydroquinone.

7. The aqueous UV resin of claim 1, wherein the aqueous UV polymer has a synthetic chemical reaction formula as follows:

in the formula, R is

The R is₁Is H or CH₃；

The above-mentionedIs IPDI or HMDI;

the above-mentionedIs polyether glycol sulfonate SPPG;

the above-mentionedIs PNA or PTA.

Technical Field

The invention relates to a water-based UV resin, in particular to a water-based UV resin for UV-Monocoat and a preparation method thereof, belonging to the technical field of UV resins.

Background

The ultraviolet curing has the advantages of fast reaction, room temperature operation, low energy consumption, no solvent, little pollution and the like. The photocuring technology has the advantages of fast curing, high production efficiency, energy conservation, environmental protection, high quality, economy, suitability for various base materials and the like, and is widely applied to various industries such as printing, packaging, advertising, building materials, decoration, electronics, communication, computers, shops, automobiles, aviation, aerospace, instruments and meters, sports, sanitation and the like.

According to the trends report, the volume of all-ball pens in 2020 exceeds two hundred million for the first time, the annual growth amplitude is 22.5%, and the expected volume of all-ball pens in 2021 reaches 2.17 hundred million. Computer, communications, and consumer electronics 3C products have increased demands for corrosion protection and appearance decoration, which are related to the properties of the coatings used. The quality of the surface coating process has become one of the important indexes for determining the grade of the product.

The traditional spraying process is a primary coating color paint and UV finishing two-coating process, and is developed into a UV one-coating process in recent two years, namely UV-Monocoat. With the updating of 3C products, the change of base materials and the strict requirements of national environmental protection on VOCs emission, in order to further improve the appearance performance, the production efficiency and the yield, a new process of aqueous UV-Monocoat is provided.

Most notebook computer materials are plastic base materials such as ABS, PS, PC, PET, ABS + PC, ABS + glass fiber, PC + glass fiber and the like, and the UV-Monocoat single coating is required to have excellent adhesive force, wear resistance, alcohol resistance, boiling resistance, scratch resistance, hand perspiration resistance, high and low temperature impact resistance, aging resistance, blocking resistance and skin feel, the metal feeling of the coating film is strong, the recoating property is not influenced, and the UV-Monocoat single coating is convenient to construct, safe and environment-friendly.

At present, the water-based UV resin is difficult to meet the technical requirements of UV-Monocoat, particularly has poor adhesive force to composite base materials such as ABS + glass fiber, PC + glass fiber and the like, is difficult to meet the technical requirements of a dark single coating, and the market more urgently develops a UV resin suitable for the UV-Monocoat single-coating water-based paint.

Disclosure of Invention

The invention aims to provide a UV-Monocoat aqueous UV resin and a preparation method thereof.

The invention grafts sulfonic acid and carboxyl groups on the molecular chain of epoxy acrylate, and the end group is a multi-active functional group modified polyamino acid WPU chain segment. The carboxyl salt type WPU is weak acid and weak base salt, more hydrophilic monomers are needed for preparing stable WPU dispersion, and the stable WPU dispersion can be stable under alkaline conditions and has reduced water resistance. And the sulfonate WPU is strong acid and strong alkali salt, can prepare WPU dispersoid with high stability and high solid content, and has better cohesiveness, water resistance and acid and alkali resistance than the carboxylate WPU. The invention combines the characteristics of the sulfonic acid and the carboxyl group, introduces the sulfonic acid and the carboxyl group into the molecular structure, and the molar ratio of the sulfonate to the carboxylate is 2:1, thereby improving the water resistance and the acid and alkali resistance of the coating film; the epoxy resin can improve the adhesion to the substrate so as to improve the mechanical property of the coating.

The invention uses DMPA (hydrophilic group) and polyurethane to form the hard segment of WPU; the soft segment of WPU is formed by polyether diol sulfonate (hydrophilic group), polyester diol and polyurethane; the polyether polyester mixed dihydric alcohol is used as a soft segment, so that the problem of viscosity of the coating before UV curing can be effectively solved, and a certain mechanical stress can be borne.

The invention adopts alicyclic diisocyanate such as isophorone diisocyanate (IPDI) or dicyclohexyl methane diisocyanate (HMDI), and introduces polyfunctional group PETA, while PETA pentaerythritol triacrylate is a monomer containing one side hydroxyl group, low volatility and fast curing, has high unsaturation degree, and has the characteristics of high crosslinking density, fast curing, good flexibility, low volatility, scratch resistance, heat resistance, chemical resistance and the like.

In order to improve the adhesion and flexibility of a coating film, a proper amount of active monomer is added into the waterborne UV polymer as a diluent, a trifunctional active monomer is selected to oxidize trimethylolpropane triacrylate (EOTPTA), the EOTPTA has three functional groups of olefin, ester and ether, the crosslinking speed is high, and due to the extension of a nonpolar carbon chain, the viscosity and the contractility of the ETPTA are smaller than those of TMPTA, and the flexibility and the adhesion are stronger; low acid value, less irritation to human body and environment friendship. Since EOTPTA is insoluble in water, an emulsifier is added to improve its water solubility.

The Monocoat single coating prepared from the waterborne UV resin has excellent adhesive force, flexibility, chemical resistance, aging resistance, oil resistance, wear resistance and tensile strength.

In order to solve the technical problems, the invention provides a water-based UV resin for UV-Monocoat, which comprises the following components in percentage by weight: 35.0-40.0% of water-based UV polymer, 3.0-6.0% of ethoxylated trimethylolpropane triacrylate, 0.3-0.5% of fatty alcohol-polyoxyethylene ether and 55.0-60.0% of deionized water.

The waterborne UV polymer is sulfonate anionic polyurethane modified acrylate, has a branched chain structure, contains 8 active functional groups, and has a molecular structural formula shown as the following formula:

in the formula, R is

R₁Is H or CH₃。

The synthesis reaction formula of the waterborne UV polymer is shown as follows:

in step (b), of formulaIs isophorone diiso-butyl etherCyanate IPDI or dicyclohexylmethane diisocyanate HMDI; in the formulaIs polyether glycol Sulfonate (SPPG); in the formulaIs poly (neopentyl glycol adipate) diol PNA or poly (trimethylolpropane adipate) diol PTA, M_n＝1000。

The invention provides a preparation method of a UV-Monocoat water-based UV resin, which comprises the following preparation steps of the preparation method according to parts by mass:

a) preparing epoxy acrylate EA: adding epoxy resin into a four-neck flask provided with a reflux condenser pipe, a thermometer, a dropping funnel and a stirrer, slowly dropping a mixture consisting of a carboxyl acrylic monomer, a catalyst and p-hydroxyanisole when the temperature rises to 80 ℃, slowly heating to 85-90 ℃ after dropping, carrying out heat preservation reaction for 2.5-4 h, then sampling every 30min to detect the acid value of the system, and stopping the reaction when the detected acid value is lower than 5mgKOH/g to prepare epoxy acrylate EA;

b) preparing a polyurethane prepolymer: adding pre-dehydrated polyether glycol sulfonate, polyester glycol, diisocyanate and dibutyltin dilaurate into a four-neck flask provided with a reflux condenser tube, a thermometer, a dropping funnel and a stirrer, stirring and heating, controlling the reaction at 80-90 ℃ for 1.5-2 h, sampling and detecting the NCO value of a system, and cooling to 65 ℃ when the detected NCO value reaches a specified theoretical value to prepare a sulfonate-containing polyurethane prepolymer WPU-1; adding a polymerization inhibitor, then adding dimethylolpropionic acid DMPA (dimethyl formamide) which is subjected to drying treatment in advance, heating to 80-90 ℃, continuing to react for 1.5-2 h, sampling to detect the NCO value of a system, cooling to 50 ℃ when the detected NCO value reaches a specified theoretical value, adding acetone accounting for 8.0-10.0% of the total material amount for dilution, and preparing a polyurethane prepolymer WPU-2 containing a hydrophilic group;

c) preparation of UV curable polyurethane prepolymer: heating to 65 ℃ in the WPU-2 prepolymer, beginning to drop metered pentaerythritol triacrylate, dropping within 1-2 h, heating to 70-75 ℃ after the dropping is finished, continuing to react until the detected NCO value reaches half of that of the polyurethane prepolymer, stopping the reaction, and cooling to 40 ℃ to obtain a UV-curable polyurethane prepolymer WPU-PETA;

d) preparing a UV-curable epoxy modified polyurethane prepolymer: adding 3.0-5.0% of acetone into WPU-PETA to adjust the viscosity of the system to a proper value, adding metered EA while stirring, heating to 65-70 ℃, reacting for 1-2.0 h, sampling and detecting the NCO value of the system, cooling to 40 ℃ when the detected NCO value is constant, and stopping the reaction to prepare UV-curable epoxy modified polyurethane prepolymer EA-WPU-PETA;

e) preparation of aqueous UV polymer dispersion: adding metered triethylamine and deionized water into the EA-WPU-PETA prepolymer, quickly stirring for 30min, heating to 40 ℃, and distilling under reduced pressure to remove acetone to obtain a water-based UV polymer dispersion;

f) preparation of a UV-Monocoat aqueous UV resin: and adding ethoxylated trimethylolpropane triacrylate and fatty alcohol-polyoxyethylene ether into the aqueous UV polymer dispersion, quickly stirring for 30min, standing, filtering and packaging to obtain the UV-Monocoat aqueous UV resin.

Wherein the epoxy resin is one of bisphenol A epoxy resin E-44 or bisphenol A epoxy resin E-51; the carboxyl-containing acrylic monomer is one of acrylic acid or methacrylic acid.

The catalyst is at least one of N, N-dimethylaniline, tetrabutylammonium bromide, N-dimethylethanolamine, N-dimethylformamide and triphenylphosphine; further, it is preferably one of a mixture of N, N-dimethylaniline and tetrabutylammonium bromide in a mass ratio of 1:1 and a mixture of N, N-dimethylethanolamine and N, N-dimethylformamide in a mass ratio of 1: 1.

The diisocyanate is at least one of isophorone diisocyanate (IPDI) and dicyclohexylmethane diisocyanate (HMDI); the polymerization inhibitor is one of 2,2,6, 6-tetramethyl piperidine nitroxide radical HTEMPO or hydroquinone.

In the step a), the molar ratio of the epoxy resin to the carboxyl-containing acrylic monomer is 1: 2; the addition amount of the catalyst is 1.5-2.5% of the total amount of reactants; the addition amount of the p-hydroxyanisole is 0.1-0.5% of the total amount of reactants.

In step b), the molar ratio of the diisocyanate to the polyglycol is NCO: OH is 3.5-3.8: 1; the molar ratio of the polyether glycol sulfonate to the polyester glycol is 1:1 to 1.2; the addition amount of the dimethylolpropionic acid is 6.0-8.0% of the total feeding amount; the addition amount of the dibutyltin dilaurate is 0.03-0.05% of the amount of diisocyanate; the addition amount of the polymerization inhibitor is 0.04-0.06% of the total feeding amount; the content of the hydrophilic group is 15.0-25.0 mmol per hundred grams of WPU-2 prepolymer, and the molar ratio of the sulfonate to the carboxylate is 2: 1.

In the step c), the mol ratio of the WPU-2 to the pentaerythritol triacrylate is NCO: PETA is 2.0-2.2: 1.

In the step d), the molar ratio of EA to WPU-PETA is OH: NCO is 3.0-3.3: 2, and the addition amount of EA is 25.0-55.0% of the total amount of EA-WPU-PETA prepolymer.

In the step e), the molar ratio of triethylamine to dimethylolpropionic acid is 1-1.02: 1; the addition amount of the deionized water is 55.0-60.0% of the total amount of the aqueous UV dispersoid.

The UV-Monocoat water-based UV resin contains 8 functional active groups, and has the characteristics of no sagging due to physical self-drying, good curing speed, good silver powder wrapping and arranging property, good color adding property, easy extinction, good adhesion to various plastic base materials and the like. The waterborne UV resin can be prepared into waterborne Monocoat photocureable coating with auxiliaries such as aluminum paste, transparent pigment, flatting agent, photoinitiator and the like and deionized water; the paint film has excellent adhesive force, wear resistance, alcohol resistance, boiling resistance, flexibility, scratch resistance, hand perspiration resistance, high and low temperature impact resistance, pollution resistance, aging resistance, blocking resistance and skin feel, and the paint film has strong metal feel and does not influence recoatability. The construction is convenient, safe and environment-friendly. The coating is widely applied to the surface of various plastic base materials such as ABS, PS, PC, PET, ABS + PC, ABS + glass fiber, PC + glass fiber and the like, such as notebook computer cover shells, pen panel, mice, keys, mobile phone rear covers, household appliances, wall switches, packaging materials, automobile interior parts and the like, and can also be coated on the surface of metal base material priming paint such as stainless steel, aluminum alloy, zinc alloy, magnesium alloy and the like.

Detailed Description

The preparation of the UV-Monocoat aqueous UV resin according to the invention is further described in connection with the following examples. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the invention.

Example 1:

an aqueous UV resin A for UV-Monocoat is prepared by the following steps:

a) preparation of epoxy acrylate E44A: in the case of a reflux condenser tube, a thermometer and a dropping funnel

Adding 0.1mol of bisphenol A epoxy resin E-44 into a four-neck flask of a hopper and a stirrer, slowly dropwise adding a mixture consisting of 0.2mol of acrylic acid, 1.5 parts of N, N-dimethylaniline and 0.2 part of p-hydroxyanisole when the temperature rises to 80 ℃, slowly heating to 85-90 ℃ after dropwise adding, carrying out heat preservation reaction for 3 hours, and then carrying out heat preservation reaction for 3 hours every 40 minutes

Sampling the acid value of a detection system, and stopping reaction when the detected acid value is lower than 5mgKOH/g to prepare epoxy acrylate E44A;

b) preparing a polyurethane prepolymer: adding 0.2mol of polyether diol sulfonate SPPG subjected to dehydration treatment in advance, 0.1mol of polyester diol PNA, 0.36mol of HMDI and 0.05 part of dibutyltin dilaurate into a four-neck flask provided with a reflux condenser tube, a thermometer, a dropping funnel and a stirrer, stirring, heating, reacting for 1.5h at 80-85 ℃, sampling and detecting the NCO value of a system, and cooling to 65 ℃ when the detected NCO value reaches a specified theoretical value to prepare a sulfonate-containing polyurethane prepolymer WPU-1; adding 0.02 part of polymerization inhibitor HTEMPO, then adding 0.1mol of dimethylolpropionic acid DMPA which is subjected to drying treatment in advance, heating to 80-90 ℃, continuing to react for 2 hours, sampling to detect the NCO value of the system, and when the detected NCO value reaches a specified theoretical value, cooling to 50 ℃, adding acetone accounting for 10.0 percent of the total material amount for dilution, thus obtaining a polyurethane prepolymer WPU-2 containing hydrophilic groups;

c) preparation of UV curable polyurethane prepolymer: heating to 65 ℃ in the WPU-2 prepolymer, beginning to drop 0.08mol of pentaerythritol triacrylate in a metered amount, dropping within 1.5h, heating to 70-72 ℃ after the dropping is finished, continuing to react until the detected NCO value reaches half of the polyurethane prepolymer, stopping the reaction, and cooling to 40 ℃ to obtain a UV-curable polyurethane prepolymer WPU-PETA;

d) preparing a UV-curable epoxy modified polyurethane prepolymer: adding 4.0% of acetone into WPU-PETA to adjust the viscosity of the system to a proper value, adding 0.1mol E44A with stirring, heating to 65-70 ℃, reacting for 1 hour, sampling and detecting the NCO value of the system, cooling to 40 ℃ when the detected NCO value is constant, and stopping the reaction to prepare UV-curable epoxy modified polyurethane prepolymer EA-WPU-PETA;

e) preparation of aqueous UV polymer dispersion: adding 0.1mol of metered triethylamine and deionized water into the EA-WPU-PETA prepolymer, quickly stirring for 30min, heating to 40 ℃, and removing acetone by reduced pressure distillation to prepare an aqueous UV polymer dispersion with the solid content of 36.5%;

f) preparation of a UV-Monocoat aqueous UV resin: adding 95.6 parts of aqueous UV polymer dispersion with the solid content of 36.5 percent into a reaction kettle, adding 4.0 parts of ethoxylated trimethylolpropane triacrylate and 0.4 part of MOA-15, quickly stirring for 30min, standing, filtering and packaging to obtain the UV-Monocoat aqueous UV resin A.

Example 2:

an aqueous UV resin B for UV-Monocoat is prepared by the following steps:

a) preparation of epoxy acrylate E44A: in the case of a reflux condenser tube, a thermometer and a dropping funnel

Adding 0.1mol of bisphenol A epoxy resin E-44 into a four-neck flask of a hopper and a stirrer, slowly dropwise adding a mixture consisting of 0.2mol of acrylic acid, 1.5 parts of N, N-dimethylaniline and 0.2 part of p-hydroxyanisole when the temperature rises to 80 ℃, slowly heating to 85-90 ℃ after dropwise adding, carrying out heat preservation reaction for 3 hours, and then carrying out heat preservation reaction for 3 hours every 40 minutes

Sampling the acid value of a detection system, and stopping reaction when the detected acid value is lower than 5mgKOH/g to prepare epoxy acrylate E44A;

b) preparing a polyurethane prepolymer: adding 0.2mol of polyether diol sulfonate SPPG subjected to dehydration treatment in advance, 0.12mol of polyester diol PTA, 0.4mol of IPDI and 0.05 part of dibutyltin dilaurate into a four-neck flask provided with a reflux condenser tube, a thermometer, a dropping funnel and a stirrer, stirring, heating, reacting for 2 hours at 80-90 ℃, sampling and detecting the NCO value of a system, and cooling to 65 ℃ when the detected NCO value reaches a specified theoretical value to obtain a sulfonate-containing polyurethane prepolymer WPU-1; adding 0.02 part of polymerization inhibitor HTEMPO, then adding 0.1mol of dimethylolpropionic acid DMPA which is subjected to drying treatment in advance, heating to 85-90 ℃, continuing to react for 2 hours, sampling to detect the NCO value of the system, and when the detected NCO value reaches a specified theoretical value, cooling to 50 ℃, adding acetone accounting for 10.0 percent of the total material amount for dilution, thus obtaining a polyurethane prepolymer WPU-2 containing hydrophilic groups;

c) preparation of UV curable polyurethane prepolymer: heating to 65 ℃ in the WPU-2 prepolymer, beginning to drop metered 0.1mol of pentaerythritol triacrylate, dropping within 1.5h, heating to 73-75 ℃ after the dropping is finished, continuing to react until the detected NCO value reaches half of that of the polyurethane prepolymer, stopping the reaction, and cooling to 40 ℃ to obtain a UV-curable polyurethane prepolymer WPU-PETA;

d) preparing a UV-curable epoxy modified polyurethane prepolymer: adding 5.0% acetone into WPU-PETA to adjust to proper system viscosity, adding 0.1mol E44A with stirring, heating to 65-70 ℃ to react for 1.5h, sampling and detecting the NCO value of the system, cooling to 40 ℃ when the detected NCO value is constant to stop the reaction, and obtaining the UV-curable epoxy modified polyurethane prepolymer EA-WPU-PETA;

e) preparation of aqueous UV polymer dispersion: adding 0.1mol of metered triethylamine and deionized water into the EA-WPU-PETA prepolymer, quickly stirring for 30min, heating to 40 ℃, and removing acetone by reduced pressure distillation to prepare an aqueous UV polymer dispersion with the solid content of 36.3%;

f) preparation of a UV-Monocoat aqueous UV resin: adding 94.5 parts of aqueous UV polymer dispersion with the solid content of 36.3 percent into a reaction kettle, adding 5.0 parts of ethoxylated trimethylolpropane triacrylate and 0.5 part of MOA-15, quickly stirring for 30min, standing, filtering and packaging to obtain the UV-Monocoat aqueous UV resin B.

The aqueous UV silver powder Monocoat is prepared by using the aqueous UV resin in the example of the invention, and the formula is shown in Table 1:

table 1: aqueous UV silver powder Monocoat formula

The spraying process comprises the following steps: ABS substrate → spraying aqueous silver powder paint (12-15 um) → baking (60 ℃ x 10min) → UV curing (medium pressure mercury lamp, 80-100 mW/cm)²,800～1000mJ/cm²)。

The performance of the waterborne UV silver powder Monocoat coating film is tested according to relevant standards, and the test results are shown in Table 2:

table 2: film coating performance test results

Although the present invention has been described in detail and with reference to exemplary embodiments thereof, it will be apparent to one skilled in the art that various changes, modifications and variations can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.