Yellowing-resistant UV curing coating and preparation method thereof

Abstract

The invention relates to a yellowing-resistant UV curing coating and a preparation method thereof, and belongs to the technical field of high polymer materials. The yellowing-resistant UV curing coating comprises the following components in parts by weight: 60-100 parts of epoxy acrylate resin, 50-90 parts of aliphatic polyurethane acrylate resin, 25-50 parts of a diluent, 1-3 parts of a modified flame retardant, 3-5 parts of a modified yellowing-resistant agent, 2-8 parts of a photoinitiator, 1-3 parts of a defoaming agent and 1-5 parts of a flatting agent, the anti-yellowing UV curing coating prepared by the invention not only has good anti-yellowing and heat-resistant effects, but also has excellent adhesive force and flame-retardant effect.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a yellowing-resistant UV-curable coating and its preparation method. Background Technology

[0002] UV-curable coatings, also known as light-curing coatings, are a new type of coating technology that combines economic, energy-saving, and environmental advantages. With its fast curing speed, mild curing conditions, low energy consumption, and zero pollution, it has become a representative technology of green and environmentally friendly coatings, and is widely used in fields such as electronic products, wood products, flooring, packaging and printing, coating of metal and glass parts, medical devices, information recording media, and optical fibers.

[0003] However, traditional UV-curable coatings have problems. Long-term or excessive UV exposure can cause aging and degradation of the adhesive layer components, leading to yellowing. Furthermore, excessively high light intensity or prolonged exposure can accelerate changes in molecular structure, generating colored products. At the same time, oxidation reactions are intensified under high-temperature environments, which can also cause yellowing. In addition, although yellowing-resistant UV-curable coatings have a certain degree of flame retardancy, their flame retardancy is no longer sufficient to meet the increasing demands of practical applications. Therefore, the development of UV-curable coatings with excellent yellowing resistance and their preparation methods has important practical significance and application value. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a UV-curable coating resistant to yellowing and its preparation method.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A UV-curable coating resistant to yellowing and its preparation method, comprising the following raw materials in parts by weight: 60-100 parts epoxy acrylate resin, 50-90 parts aliphatic polyurethane acrylate resin, 25-50 parts diluent, 1-3 parts modified flame retardant, 3-5 parts modified anti-yellowing agent, 2-8 parts photoinitiator, 1-3 parts defoamer, and 1-5 parts leveling agent.

[0007] The diluent is polyethylene glycol dimethacrylate;

[0008] The photoinitiator is TPO;

[0009] The defoamer mentioned is BASF 2410AC;

[0010] The leveling agent mentioned is BYK-UV3500.

[0011] The modified anti-yellowing agent is prepared by the following method:

[0012] Step A1: 1,3-Dimethyl-6-aminourea pyrimidine was added to tetrahydrofuran and dispersed evenly. Allyl isothiocyanate was slowly added under stirring. The temperature was raised to 45-55℃ and the reaction was continued to be stirred for 3-4 hours. After the reaction was completed, the mixture was filtered, washed and dried to obtain the compound.

[0013] Furthermore, the ratio of 1,3-dimethyl-6-aminourea pyrimidine, tetrahydrofuran, and allyl isothiocyanate is 0.01-0.03 mol: 10-15 mL: 0.01-0.03 mol;

[0014] The compound was prepared by reacting the amino group of 1,3-dimethyl-6-aminouracil with the isothiocyanate group of allyl isothiocyanate.

[0015] Step A2: Mix 2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole and triethylamine, heat to 40°C, add 1-epoxyalkylmethyl-3,5-diallyl isocyanurate and chloroform, mix well, then add Amberlyst-15 ion exchange resin, heat to 55°C in an ultrasonic water bath and react for 4-5 hours. After the reaction is complete, filter, rotary evaporate, and vacuum dry to obtain the preproduct.

[0016] Furthermore, the ratio of 2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole, triethylamine, 1-epoxyalkylmethyl-3,5-diallyl isocyanurate, chloroform, and Amberlyst-15 ion exchange resin is 0.01-0.03 mol: 2.1-2.5 mL: 0.01-0.03 mol: 5 mL: 0.8-1.0 g;

[0017] Secondly, the preproduct was prepared by reacting the hydroxyl group of 2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole with the epoxy group of 1-epoxyalkylmethyl-3,5-diallyl isocyanurate.

[0018] Step A3: Disperse the compound and benzoyl peroxide evenly in xylene, then add the pre-product and stir evenly. Under nitrogen protection, heat to 90°C and react for 4.5 h. Distill under reduced pressure, cool, wash, filter, and vacuum dry to obtain the modified anti-yellowing agent.

[0019] Furthermore, the ratio of the compound, benzoyl peroxide, xylene, and preproduct is 0.01-0.03 mol: 0.16 g: 50-60 mL: 0.01-0.03 mol;

[0020] Finally, a modified anti-yellowing agent was prepared by copolymerizing the carbon-carbon double bonds of the compound and the preproduct.

[0021] The modified flame retardant is prepared by the following method:

[0022] Step B1: Under nitrogen atmosphere, γ-glycidoxypropyltrimethoxysilane and anhydrous ethanol are mixed evenly, then phosphoric acid and triethylamine are added, and the mixture is heated to 70-80℃ and reacted for 5 hours. After the reaction is completed, the system is cooled to room temperature, washed, rotary evaporated, and dried to obtain the intermediate.

[0023] Furthermore, the ratio of γ-glycidoxypropyltrimethoxysilane, anhydrous ethanol, phosphoric acid, and triethylamine is 0.01-0.03 mol: 40-60 mL: 0.01-0.03 mol: 0.5-1 g;

[0024] The intermediate was prepared by reacting the silanol groups from the hydrolysis of γ-glycidoxypropyltrimethoxysilane with the hydroxyl groups of phosphoric acid.

[0025] Step B2: Mix 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and the intermediate evenly, then add N,N-dimethylacetamide, heat to 130-140℃, stir and react for 3 hours. After the reaction is completed, distill under reduced pressure, wash, and dry under vacuum to obtain the modified flame retardant.

[0026] Furthermore, the ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, intermediate, and N,N-dimethylacetamide is 0.01-0.03 mol: 0.01-0.03 mol: 30-50 mL;

[0027] Finally, the modified flame retardant was prepared by reacting the epoxy groups of the intermediate with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0028] A method for preparing a UV-curable coating resistant to yellowing specifically includes the following steps:

[0029] S1. Mix epoxy acrylate resin, aliphatic polyurethane acrylate resin and diluent evenly, stir at 800-1000 rpm for 5-10 min to obtain pretreated material.

[0030] S2. Mix the pretreatment material, modified flame retardant, modified anti-yellowing agent, photoinitiator, defoamer and leveling agent, stir at 1000-1200 rpm for 30-50 min, filter, and use a UV curing mechanism to obtain an anti-yellowing UV-cured coating.

[0031] The beneficial effects of this invention are:

[0032] The anti-yellowing UV-curable coating of the present invention has good anti-yellowing and heat resistance, and also has excellent adhesion and flame retardant effect, further extending its service life.

[0033] The modified anti-yellowing agent prepared by this invention has excellent anti-yellowing effect. The nitrogen atom of 1,3-dimethyl-6-aminoureapyrimidine in the compound can capture alkyl and peroxy radicals generated by the thermal degradation of epoxy acrylate resin through its lone pair electrons, terminating the chain reaction, delaying the thermo-oxidative aging process, and effectively improving the thermal stability and aging resistance of the material. Simultaneously, thiourea has good anti-ozone aging and anti-thermal oxidation properties, can capture free radicals, terminate the chain reaction, and delay the aging of the resin, thereby effectively extending the service life of the coating and reducing the cost of use. In addition, 2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole, through… By utilizing its conjugated double bonds and aromatic rings, it can efficiently absorb ultraviolet light. Through inducing internal thermal vibrations, it breaks intrinsic hydrogen bonds, converting the energy of ultraviolet light into heat or light energy, significantly reducing the yellowing effect of ultraviolet light on materials. The six-membered ring structure of 1-epoxyethylenemethyl-3,5-diallyl isocyanurate in the preproduct contains no active hydrogens, endowing the isocyanurate ring with good thermal and hydrolytic stability, improving the heat resistance of the material, and reducing the possibility of yellowing of the coating due to high temperatures. Furthermore, this modified anti-yellowing agent has good compatibility with coatings and can be uniformly dispersed in the coating matrix, synergistically exerting its heat resistance and anti-yellowing effects.

[0034] The modified flame retardant prepared by this invention exhibits both high flame retardancy and environmental friendliness through a synergistic effect of phosphorus-oxygen-silicon. Its phosphorus-based components generate a phosphate protective layer during combustion, which isolates oxygen and promotes char formation, thus providing heat and oxygen insulation and inhibiting flame spread. It also generates free radicals, capturing combustion-supporting free radicals during combustion, interrupting the combustion chain reaction, and preventing further combustion and fire spread. The synergistic effect of high-bond-energy Si-O bonds and phosphorus-oxygen double bonds enhances the thermal stability of the material. Simultaneously, silicon improves the adhesion of coatings, making the coating more robust and durable. Additionally, γ-glycidyl ether... Oxypropyltrimethoxysilane promotes the formation of a dense char layer on its surface during combustion, inhibiting heat transfer and oxygen diffusion, slowing down the combustion process, and reducing smoke generation. Furthermore, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, as a phosphaphenanthrene compound with high thermal stability, promotes the formation of a dense and continuous char layer during combustion, synergistically enhancing the flame-retardant effect with the phosphorus-oxygen double bond and extending service life. In addition, the modified flame retardant prepared in this invention is halogen-free, helping to reduce environmental pollution and ecosystem damage, is harmless to human health, and achieves sustainable development. Detailed Implementation

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1: A method for preparing a UV-curable coating resistant to yellowing, specifically including the following steps:

[0037] S1. Weigh the raw materials according to the following parts by weight: 60 parts epoxy acrylate resin, 50 parts aliphatic polyurethane acrylate resin, 25 parts diluent, 1 part modified flame retardant (prepared in this embodiment), 3 parts modified anti-yellowing agent (prepared in this embodiment), 2 parts photoinitiator, 1 part defoamer, and 1 part leveling agent; mix the epoxy acrylate resin, aliphatic polyurethane acrylate resin, and polyethylene glycol dimethacrylate evenly, and stir at 800 rpm for 5 minutes to obtain the pretreated material.

[0038] S2. Mix the pretreatment material, modified flame retardant, modified anti-yellowing agent, TPO, BASF 2410AC and BYK-UV3500, stir at 1000 rpm for 30 min, filter, and use a UV curing mechanism to obtain an anti-yellowing UV-cured coating.

[0039] The modified anti-yellowing agent is prepared by the following method:

[0040] Step A1: 0.01 mol of 1,3-dimethyl-6-aminourea pyrimidine was added to 10 mL of tetrahydrofuran and dispersed evenly. 0.01 mol of allyl isothiocyanate was slowly added under stirring. The temperature was raised to 45 °C and the reaction was continued to be stirred for 3 h. After the reaction was completed, the mixture was filtered, washed and dried to obtain the compound.

[0041] Step A2: Mix 0.01 mol of 2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole and 2.1 mL of triethylamine, heat to 40 °C, add 0.01 mol of 1-epoxyalkylmethyl-3,5-diallyl isocyanurate and 5 mL of chloroform, mix well, then add 0.8 g of Amberlyst-15 ion exchange resin, heat to 55 °C in an ultrasonic water bath and react for 4 h. After the reaction is complete, filter, rotary evaporate, and vacuum dry to obtain the preproduct;

[0042] Step A3: Disperse 0.01 mol of the compound and 0.16 g of benzoyl peroxide evenly in 50 mL of xylene, then add 0.01 mol of the preproduct and stir evenly. Under nitrogen protection, heat to 90 °C and react for 4.5 h. Distill under reduced pressure, cool, wash, filter, and vacuum dry to obtain the modified anti-yellowing agent.

[0043] The modified flame retardant is prepared by the following method:

[0044] Step B1: Under nitrogen atmosphere, 0.01 mol γ-glycidoxypropyltrimethoxysilane and 40 mL anhydrous ethanol were mixed evenly, and then 0.01 mol phosphoric acid and 0.5 g triethylamine were added. The mixture was heated to 70 °C and reacted for 5 h. After the reaction was completed, the system was cooled to room temperature, washed, rotary evaporated, and dried to obtain the intermediate.

[0045] Step B2: Mix 0.01 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 0.01 mol of intermediate evenly, then add 30 mL of N,N-dimethylacetamide, heat to 130 °C, stir and react for 3 h. After the reaction is complete, distill under reduced pressure, wash, and dry under vacuum to obtain the modified flame retardant.

[0046] Example 2: A method for preparing a UV-curable coating resistant to yellowing, specifically including the following steps:

[0047] S1. Weigh the raw materials according to the following parts by weight: 80 parts epoxy acrylate resin, 70 parts aliphatic polyurethane acrylate resin, 37.5 parts diluent, 2 parts modified flame retardant (prepared in this embodiment), 4 parts modified anti-yellowing agent (prepared in this embodiment), 5 parts photoinitiator, 2 parts defoamer, and 3 parts leveling agent; mix the epoxy acrylate resin, aliphatic polyurethane acrylate resin, and polyethylene glycol dimethacrylate evenly, and stir at 900 rpm for 7.5 min to obtain the pretreated material;

[0048] S2. Mix the pretreatment material, modified flame retardant, modified anti-yellowing agent, TPO, BASF 2410AC and BYK-UV3500, stir at 1100 rpm for 40 min, filter, and use a UV curing mechanism to obtain an anti-yellowing UV-cured coating.

[0049] The modified anti-yellowing agent is prepared by the following method:

[0050] Step A1: 0.02 mol of 1,3-dimethyl-6-aminoureapyrimidine was added to 12.5 mL of tetrahydrofuran and dispersed evenly. 0.02 mol of allyl isothiocyanate was slowly added under stirring. The temperature was raised to 50 °C and the reaction was continued to be stirred for 3.5 h. After the reaction was completed, the mixture was filtered, washed and dried to obtain the compound.

[0051] Step A2: Mix 0.02 mol of 2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole and 2.3 mL of triethylamine, heat to 40 °C, add 0.02 mol of 1-epoxyalkylmethyl-3,5-diallyl isocyanurate and 5 mL of chloroform, mix well, then add 0.89 g of Amberlyst-15 ion exchange resin, heat to 55 °C in an ultrasonic water bath and react for 4.5 h. After the reaction is complete, filter, rotary evaporate, and vacuum dry to obtain the preproduct;

[0052] Step A3: Disperse 0.02 mol of the compound and 0.16 g of benzoyl peroxide evenly in 55 mL of xylene, then add 0.02 mol of the preproduct and stir evenly. Under nitrogen protection, heat to 90 °C and react for 4.5 h. Distill under reduced pressure, cool, wash, filter, and vacuum dry to obtain the modified anti-yellowing agent.

[0053] The modified flame retardant is prepared by the following method:

[0054] Step B1: Under nitrogen atmosphere, 0.02 mol γ-glycidoxypropyltrimethoxysilane and 50 mL anhydrous ethanol were mixed evenly, and then 0.02 mol phosphoric acid and 0.75 g triethylamine were added. The mixture was heated to 75 °C and reacted for 5 h. After the reaction was completed, the system was cooled to room temperature, washed, rotary evaporated, and dried to obtain the intermediate.

[0055] Step B2: Mix 0.02 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 0.02 mol of intermediate evenly, then add 40 mL of N,N-dimethylacetamide, heat to 135 °C, stir and react for 3 h. After the reaction is completed, distill under reduced pressure, wash, and dry under vacuum to obtain the modified flame retardant.

[0056] Example 3: A method for preparing a UV-curable coating resistant to yellowing, specifically including the following steps:

[0057] S1. Weigh the raw materials according to the following parts by weight: 100 parts epoxy acrylate resin, 90 parts aliphatic polyurethane acrylate resin, 50 parts diluent, 3 parts modified flame retardant (prepared in this embodiment), 5 parts modified anti-yellowing agent (prepared in this embodiment), 8 parts photoinitiator, 3 parts defoamer, and 5 parts leveling agent; mix the epoxy acrylate resin, aliphatic polyurethane acrylate resin, and polyethylene glycol dimethacrylate evenly, and stir at 1000 rpm for 10 min to obtain the pretreated material.

[0058] S2. Mix the pretreatment material, modified flame retardant, modified anti-yellowing agent, TPO, BASF 2410AC and BYK-UV3500, stir at 1200 rpm for 50 min, filter, and use a UV curing mechanism to obtain an anti-yellowing UV-cured coating.

[0059] The modified anti-yellowing agent is prepared by the following method:

[0060] Step A1: 0.03 mol of 1,3-dimethyl-6-aminourea pyrimidine was added to 15 mL of tetrahydrofuran and dispersed evenly. 0.03 mol of allyl isothiocyanate was slowly added under stirring. The temperature was raised to 55 °C and the reaction was continued to be stirred for 4 h. After the reaction was completed, the mixture was filtered, washed and dried to obtain the compound.

[0061] Step A2: Mix 0.03 mol of 2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole and 2.5 mL of triethylamine, heat to 40 °C, add 0.03 mol of 1-epoxyalkylmethyl-3,5-diallyl isocyanurate and 5 mL of chloroform, mix well, then add 1.0 g of Amberlyst-15 ion exchange resin, heat to 55 °C in an ultrasonic water bath and react for 5 h. After the reaction is complete, filter, rotary evaporate, and vacuum dry to obtain the preproduct;

[0062] Step A3: Disperse 0.03 mol of the compound and 0.16 g of benzoyl peroxide evenly in 60 mL of xylene, then add 0.03 mol of the preproduct and stir evenly. Under nitrogen protection, heat to 90 °C and react for 4.5 h. Distill under reduced pressure, cool, wash, filter, and vacuum dry to obtain the modified anti-yellowing agent.

[0063] The modified flame retardant is prepared by the following method:

[0064] Step B1: Under nitrogen atmosphere, 0.03 mol γ-glycidoxypropyltrimethoxysilane and 60 mL anhydrous ethanol were mixed evenly, and then 0.03 mol phosphoric acid and 1 g triethylamine were added. The mixture was heated to 80 °C and reacted for 5 h. After the reaction was completed, the system was cooled to room temperature, washed, rotary evaporated, and dried to obtain the intermediate.

[0065] Step B2: Mix 0.03 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 0.03 mol of intermediate evenly, then add 50 mL of N,N-dimethylacetamide, heat to 140 °C, stir and react for 3 h. After the reaction is completed, distill under reduced pressure, wash, and dry under vacuum to obtain the modified flame retardant.

[0066] Comparative Example 1: This comparative example is a UV-curable coating that is resistant to yellowing. The difference between this example and Example 3 is that an equal amount of [2-hydroxy-4-(octoxy)phenyl]phenyl ketone is used instead of the modified anti-yellowing agent prepared in Example 3. All other aspects are the same.

[0067] Comparative Example 2: This comparative example is a UV-curable coating that is resistant to yellowing. The difference between this example and Example 3 is that an equal amount of magnesium hydroxide is used instead of the modified flame retardant prepared in Example 3. All other aspects are the same.

[0068] Performance testing: The anti-yellowing UV-curable coatings prepared in Examples 1-3 and Comparative Examples 1-2 were applied to PET release film using an automatic coater with a 60µm wire bar at a speed of 30m / min. A high-pressure mercury lamp was used as the UV light source with a light intensity of 25mw / cm². -2The cured coating was aged at 120℃ and 100% humidity for 24 hours to test for yellowing; the flame retardancy rating of the coating was tested according to standard GB / T2408-2008; the adhesion was tested according to standard GB / T9286-88; the test results are shown in Table 1 below:

[0069] Table 1

[0070]

[0071] As can be seen from the test data in Table 1, the anti-yellowing UV-curable coating prepared by the present invention has good anti-yellowing and heat resistance. Table 1 also shows that the anti-yellowing UV-curable coating prepared by the present invention has good adhesion and flame retardant effect, and extends service life.

[0072] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a UV-curable coating resistant to yellowing, characterized in that, Specifically, the following steps are included: S1. Weigh the raw materials according to the following parts by weight: 60-100 parts epoxy acrylate resin, 50-90 parts aliphatic polyurethane acrylate resin, 25-50 parts diluent, 1-3 parts modified flame retardant, 3-5 parts modified anti-yellowing agent, 2-8 parts photoinitiator, 1-3 parts defoamer, and 1-5 parts leveling agent; mix the epoxy acrylate resin, aliphatic polyurethane acrylate resin, and diluent evenly, and stir at 800-1000 rpm for 5-10 minutes to obtain the pretreated material. S2. Mix the pretreatment material, modified flame retardant, modified anti-yellowing agent, photoinitiator, defoamer and leveling agent, stir at 1000-1200 rpm for 30-50 min, filter, and use ultraviolet light curing mechanism to obtain anti-yellowing UV curing coating. The modified anti-yellowing agent is prepared by the following method: Step A1: 1,3-Dimethyl-6-aminourea pyrimidine was added to tetrahydrofuran and dispersed evenly. Allyl isothiocyanate was slowly added under stirring. The temperature was raised to 45-55℃ and the reaction was continued to be stirred for 3-4 hours. After the reaction was completed, the mixture was filtered, washed and dried to obtain the compound. Step A2: Mix 2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole and triethylamine, heat to 40°C, add 1-epoxyalkylmethyl-3,5-diallyl isocyanurate and chloroform, mix well, then add Amberlyst-15 ion exchange resin, heat to 55°C in an ultrasonic water bath and react for 4-5 hours. After the reaction is complete, filter, rotary evaporate, and vacuum dry to obtain the preproduct. Step A3: Disperse the compound and benzoyl peroxide evenly in xylene, then add the preproduct and stir evenly. Under nitrogen protection, heat to 90°C and react for 4.5 h. Distill under reduced pressure, cool, wash, filter, and vacuum dry to obtain the modified anti-yellowing agent.

2. The method for preparing a yellowing-resistant UV-curable coating according to claim 1, characterized in that, In step A1, the ratio of 1,3-dimethyl-6-aminourea pyrimidine, tetrahydrofuran, and allyl isothiocyanate is 0.01-0.03 mol: 10-15 mL: 0.01-0.03 mol.

3. The method for preparing a UV-curable coating resistant to yellowing according to claim 1, characterized in that, In step A2, the ratio of 2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole, triethylamine, 1-epoxyethylenemethyl-3,5-diallyl isocyanurate, chloroform, and Amberlyst-15 ion exchange resin is 0.01-0.03 mol: 2.1-2.5 mL: 0.01-0.03 mol: 5 mL: 0.8-1.0 g.

4. The method for preparing a yellowing-resistant UV-curable coating according to claim 1, characterized in that, In step A3, the ratio of the compound, benzoyl peroxide, xylene, and preproduct is 0.01-0.03 mol: 0.16 g: 50-60 mL: 0.01-0.03 mol.

5. The method for preparing a UV-curable coating resistant to yellowing according to claim 1, characterized in that, The modified flame retardant is prepared by the following method: Step B1: Under nitrogen atmosphere, γ-glycidoxypropyltrimethoxysilane and anhydrous ethanol are mixed evenly, then phosphoric acid and triethylamine are added, and the mixture is heated to 70-80℃ and reacted for 5 hours. After the reaction is completed, the system is cooled to room temperature, washed, rotary evaporated, and dried to obtain the intermediate. Step B2: Mix 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and the intermediate evenly, then add N,N-dimethylacetamide, heat to 130-140℃, stir and react for 3 hours. After the reaction is completed, distill under reduced pressure, wash, and dry under vacuum to obtain the modified flame retardant.

6. The method for preparing a UV-curable coating resistant to yellowing according to claim 5, characterized in that, In step B1, the ratio of γ-glycidyl etheroxypropyltrimethoxysilane, anhydrous ethanol, phosphoric acid, and triethylamine is 0.01-0.03 mol: 40-60 mL: 0.01-0.03 mol: 0.5-1 g.

7. The method for preparing a UV-curable coating resistant to yellowing according to claim 5, characterized in that, In step B2, the ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, intermediate, and N,N-dimethylacetamide is 0.01-0.03 mol: 0.01-0.03 mol: 30-50 mL.

8. The method for preparing a UV-curable coating resistant to yellowing according to claim 1, characterized in that, The diluent is polyethylene glycol dimethacrylate, the photoinitiator is TPO, the defoamer is BASF 2410AC, and the leveling agent is BYK-UV3500.

9. A UV-curable coating resistant to yellowing, characterized in that, Prepared according to any one of claims 1-8.

Images