Water-based UV photocureable coating and preparation method thereof

Abstract

The invention discloses a water-based UV (ultraviolet) photocureable coating and a preparation method thereof, belongs to the technical field of coatings, and aims at surface stickiness and insufficient hardness and gloss caused by oxygen inhibition, a double modified dispersion of siloxane and allyl ether is introduced into a PUA (polyurethane acrylate) molecular chain to be matched with a water-soluble monomer and a photoinitiator; the surface of siloxane is enriched to form a low oxygen permeation layer, and allyl ether captures peroxy free radicals to construct a physical shielding and chemical capture synergistic system. The coating film hardness, wear resistance and hand feeling are remarkably improved, and the coating film is green, low in VOC, simple and convenient in process and wide in application.

Description

Technical Field

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

[0002] Waterborne UV-curable coatings, with their significant advantages such as low volatile organic compound (VOC) emissions, fast curing speed, and low energy consumption, are gradually becoming an ideal alternative to traditional solvent-based coatings, and have been widely used in fields such as wooden furniture, plastic products, automotive interior parts, and consumer electronics casings. This technology stabilizes core components such as photosensitive prepolymers, monomers, and photoinitiators in the form of an aqueous dispersion. After application to the substrate surface, the moisture evaporates first, and then under high-energy ultraviolet light irradiation, the photosensitive components within the system undergo rapid free radical polymerization and cross-linking reactions, thereby instantly forming a high-performance coating film.

[0003] However, in practical applications, waterborne UV curing technology consistently faces a core technical bottleneck – the oxygen inhibition effect. During UV curing, oxygen molecules in the atmosphere act as highly efficient free radical quenchers. They rapidly capture primary active free radicals generated by photoinitiators or growing polymer chain free radicals, generating extremely low-activity peroxide free radicals, thereby effectively terminating or significantly slowing down the growth reaction of the polymerization chain. This inhibitory effect is most severe on the surface layer where the coating is in direct contact with air, directly leading to a series of fatal defects such as incomplete curing, stickiness, low gloss, insufficient hardness, and poor scratch resistance.

[0004] To overcome the oxygen inhibition problem, existing technologies typically employ the following strategies: (1) Increase the amount of photoinitiator: ensure polymerization by generating free radicals that far exceed oxygen consumption. However, this will significantly increase costs, and excessive initiator and its residual pyrolysis fragments will cause yellowing of the coating film in the later stage.

[0005] (2) Use of amine additives: Amine compounds can consume oxygen and generate new active free radicals, but they are easily oxidized and discolored, which can also lead to yellowing of the coating and affect its appearance.

[0006] (3) Inert gas protection: UV curing in an inert gas environment such as nitrogen can isolate oxygen from the source. However, this method requires additional gas supply equipment and a sealed curing chamber, which involves huge equipment investment and complex process, and is not suitable for coating large-scale or irregularly shaped workpieces.

[0007] (4) Increase UV irradiation intensity: Increase the total irradiation energy by increasing the power of the UV lamp or reducing the conveyor belt speed. This method is not only energy-intensive, but may also cause the coating to become brittle due to over-curing, and may even damage the heat-sensitive substrate due to excessive heat generation.

[0008] In addition to solving the well-known technical challenge of oxygen inhibition polymerization, waterborne UV coatings also face the objective need to improve the surface texture (such as smoothness) and durability (such as abrasion resistance) of the coating film when applied to high-end consumer electronics, automotive interiors and other fields. The existing technical solutions mentioned above have not considered or are unable to simultaneously improve these properties.

[0009] In summary, developing a highly efficient antioxidant and polymerization-inhibiting mechanism that can be built from within the coating system, enabling the coating to achieve rapid and complete surface curing in an atmospheric environment, and further improving the overall physicochemical properties of the coating film, especially abrasion resistance and feel, is a technical problem that urgently needs to be solved by those skilled in the art, and has significant market value and important practical significance. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the prior art and provide a water-based UV-curable coating and its preparation method that can effectively resist oxygen inhibition, have excellent surface curing performance, and also have high wear resistance and excellent feel.

[0011] The objective of this invention can be achieved through the following technical solutions: A water-based UV-curable coating comprises the following raw materials in parts by weight: Siloxane and allyl ether dual-modified waterborne polyurethane acrylate dispersion: 140-160 parts; UV-curable monomer: 35-45 parts; Photoinitiator: 5-8 parts; Leveling agent: 0.1–1.0 parts; Defoamer: 0.1–1.0 parts; Deionized water: 50 parts.

[0012] Furthermore, the photocurable monomer is selected from one of tripropylene glycol diacrylate and 1,6-hexanediol diacrylate.

[0013] Furthermore, the photoinitiator is selected from one or two of 2-hydroxy-2-methyl-1-phenyl-1-propanone and phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, mixed in any proportion.

[0014] The core of this invention lies in the siloxane and allyl ether dual-modified waterborne polyurethane acrylate dispersion. Through molecular design, this invention simultaneously introduces two chemical structures with specific functions onto a single polyurethane acrylate (PUA) molecular chain, constructing a dual antioxidant polymerization inhibitory system with synergistic effects of "physical shielding" and "chemical capture".

[0015] The aforementioned "physical shielding" mechanism is achieved by introducing low-surface-energy polydimethylsiloxane segments into the PUA molecular chain. During the film-forming process after coating application and water evaporation, due to the surface tension gradient, these siloxane segments spontaneously migrate and accumulate towards the coating-air interface, forming a dense, nanoscale siloxane layer with extremely low oxygen permeability. This layer acts like a "liquid protective film" covering the surface of the liquid coating before curing, effectively blocking most of the oxygen in the air from penetrating into the coating, thus providing a low-oxygen environment for the subsequent photocuring reaction.

[0016] The aforementioned "chemical capture" mechanism is achieved by introducing allyl ether groups containing active α-hydrogen into the PUA molecular chain. For small amounts of oxygen that penetrate the physical shielding layer or are dissolved in the coating, the peroxide radicals (ROO·) formed under light irradiation react with the allyl ether groups. The active α-hydrogen on the allyl ether group converts the highly reactive peroxide radical into a less reactive hydroperoxide (ROOH) through a hydrogen transfer reaction, while simultaneously forming a carbon-centered free radical that still possesses polymerization activity. This free radical can continue to participate in the polymerization reaction, thereby preventing chain termination and ensuring the smooth progress of the photocuring reaction.

[0017] The ingenuity of this invention lies in combining and enhancing two different mechanisms of oxygen inhibition: "physical shielding" and "chemical capture." Physical shielding, as the first line of defense, significantly reduces the oxygen concentration within the system, greatly alleviating the burden on chemical capture. Meanwhile, chemical capture, as the second line of defense, eliminates the influence of residual oxygen, ensuring complete curing of the outermost layer. The synergistic effect of these two mechanisms far exceeds the simple sum of any single mechanism, achieving a 1+1>2 technical effect, thus completely solving the oxygen inhibition problem.

[0018] Furthermore, the introduced siloxane segments, while providing physical shielding, also possess low friction coefficients and high flexibility, resulting in an exceptionally smooth surface feel and outstanding abrasion resistance in the final cured coating. This solves the inherent technical challenge of improving surface texture and durability in the field of water-based UV coatings.

[0019] Preferably, the siloxane and allyl ether dual-modified waterborne polyurethane acrylate dispersion is prepared by reacting the following raw materials in parts by weight: Polyisocyanate: 10-15 parts; Macromolecular diols: 35–45 parts; Hydroxyl-terminated polydimethylsiloxane: 1-3 parts; Chain extender containing hydrophilic groups: 2-3 parts; Allyl ether capping agent: 0.5–1.0 parts; Acrylic end-capping agent: 1-2 parts; Catalyst: 0.01–0.02 parts; Neutralizing agent: 2.0–2.5 parts; Deionized water: 50-60 parts.

[0020] Furthermore, the polyisocyanate is isophorone diisocyanate; the macromolecular diol is polytetrahydrofuran ether diol; the chain extender containing hydrophilic groups is dimethylolpropionic acid; the allyl ether end-capping agent is trimethylolpropane monoallyl ether; the acrylate end-capping agent is hydroxyethyl acrylate; the catalyst is dibutyltin dilaurate; and the neutralizing agent is triethylamine.

[0021] Furthermore, the preparation method of the siloxane and allyl ether dual-modified waterborne polyurethane acrylate dispersion includes the following steps: (1) Add measured amounts of polyisocyanate, macromolecular diol, hydroxyl-terminated polydimethylsiloxane and chain extender containing hydrophilic groups to a reaction vessel, and stir at 75-85°C for 2-3 hours to obtain a prepolymer; (2) Cool the prepolymer to 50-60°C, add a measured amount of neutralizing agent, react for 30 minutes, then add a measured amount of allyl ether end-capping agent and acrylate end-capping agent, and continue the reaction for 1-2 hours to obtain modified polyurethane acrylate resin. (3) The modified polyurethane acrylate resin was added to a measured amount of deionized water under stirring to obtain a waterborne polyurethane acrylate dispersion with dual modification of siloxane and allyl ether.

[0022] Furthermore, the preparation method of the water-based UV-curable coating includes the following steps: Weigh and mix the siloxane and allyl ether dual-modified waterborne polyurethane acrylate dispersion, UV-curing monomer, photoinitiator, leveling agent, defoamer, and deionized water according to the mass ratio, stir at room temperature for 30-60 minutes, and then filter through a 200-mesh filter to obtain the waterborne UV-curing coating.

[0023] The beneficial effects of this invention are: (1) Highly efficient anti-oxidation and polymerization inhibition, achieving perfect surface drying: This invention greatly reduces the inhibitory effect of oxygen on photocuring reaction through the dual synergistic mechanism of "physical shielding" and "chemical capture" integrated on the molecular chain, so that the coating can achieve rapid and non-sticky surface curing in ordinary atmospheric environment, without the need for inert gas protection or excessive addition of additives, saving costs and simplifying the process.

[0024] (2) Synergistic effect and excellent overall performance: The cured coating film has high surface hardness and full gloss. At the same time, due to the introduction of siloxane segments and complete surface curing, the coating film is synergistically endowed with excellent smooth feel, excellent wear resistance and anti-graffiti properties. Its overall performance is far superior to water-based UV coatings prepared using existing technical solutions.

[0025] (3) Green and environmentally friendly, with wide applicability: This invention is a water-based system with extremely low VOC content, which is environmentally friendly; the preparation process is simple, and the raw materials used are all commercially available conventional chemicals, so the cost is controllable and easy to industrialize. It can be widely used in coating various substrates (such as plastics, wood, metals, etc.) with high requirements for surface performance and environmental protection. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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. Meanwhile, unless otherwise specified, the raw materials, reagents, or devices used in the following embodiments can be obtained from conventional commercial channels or by existing known methods. Some raw materials and specifications are as follows: Raw materials and specifications used: Isophorone diisocyanate (IPDI): Industrial grade, Wanhua Chemical.

[0027] Polytetrahydrofuran ether diol (PTMG-2000): Number average molecular weight 2000 g / mol, industrial grade, BASF.

[0028] Hydroxyl-terminated polydimethylsiloxane: Trademark name KF-6001, number average molecular weight approximately 1000 g / mol, Shin-Etsu Chemical.

[0029] Dimethylolpropionic acid (DMPA): Industrial grade, Jinan Taixing.

[0030] Trimethylolpropane monoallyl ether (TMPMAE): Industrial grade, Perstorp.

[0031] Hydroxyethyl acrylate (HEA): Industrial grade, Dow Chemical.

[0032] Dibutyltin dilaurate (DBTDL): Analytical grade, Sinopharm Group.

[0033] Triethylamine (TEA): Analytical grade, Sinopharm Group.

[0034] Tripropylene glycol diacrylate (TPGDA): Industrial grade, Sartoma.

[0035] 1,6-Hexanediol diacrylate (HDDA): Industrial grade, Sartoma.

[0036] Photoinitiator 1173 (2-hydroxy-2-methyl-1-phenyl-1-propanone): Industrial grade, IGM Resins.

[0037] Photoinitiator 819 (phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide): Industrial grade, BASF.

[0038] Leveling agent: BYK-348, BYK Chemicals.

[0039] Defoamer: TEGO Foamex 810, Evonik Industries.

[0040] All raw materials are commercially available. Example

[0041] A water-based UV-curable coating and its preparation method: (1) Preparation of waterborne polyurethane acrylate dispersion modified by siloxane and allyl ether (denoted as WPUA-Si-AE): In a 1000 mL four-necked flask equipped with a mechanical stirrer, thermometer, reflux condenser, and nitrogen protection, 100 g IPDI, 350 g PTMG-2000, 10 g hydroxyl-terminated polydimethylsiloxane (KF-6001), 20 g DMPA, and 0.1 g DBTDL were added sequentially. Stirring was started, and the temperature was raised to 75 °C and maintained for 2 hours. After the reaction was complete, the system was cooled to 50 °C, and 10 g TEA was added. Stirring continued for 30 minutes for neutralization. Then, a mixture of 5 g TMPMAE and 10 g HEA was added through a constant-pressure dropping funnel, with the addition completed within 15 minutes. After the addition was complete, the reaction was maintained at 55 °C for 1 hour. Fourier transform infrared spectroscopy (FTIR) was used to detect the reaction at 2270 cm⁻¹. -1 After the characteristic absorption peak of -NCO at the site essentially disappeared, the reaction was stopped. In another beaker containing 500g of deionized water and with high-speed stirring (1200 rpm) turned on, the synthesized resin product was forced into the water over 30 minutes for emulsification. After emulsification, stirring was continued for another 30 minutes to obtain a milky white, stable WPUA-Si-AE dispersion.

[0042] (2) Preparation of water-based UV-curable coatings: In a 500 mL stirring vessel, 140 g of the WPUA-Si-AE dispersion prepared above, 35 g of TPGDA, 3 g of photoinitiator 1173, 2 g of photoinitiator 819, 0.1 g of BYK-348, 0.1 g of TEGO Foamex 810, and 50 g of deionized water were added sequentially. Mechanical stirring was started and the mixture was stirred at medium speed at room temperature for 30 minutes until completely homogeneous. After stirring was stopped, the mixture was filtered through a 200-mesh nylon filter to obtain the waterborne UV-curable coating of Example 1, for later use. Example

[0043] A water-based UV-curable coating and its preparation method: (1) Preparation of waterborne polyurethane acrylate dispersion modified by siloxane and allyl ether (denoted as WPUA-Si-AE): In a 1000 mL four-necked flask equipped with a mechanical stirrer, thermometer, reflux condenser, and nitrogen protection, 111 g IPDI, 400 g PTMG-2000, 20 g hydroxyl-terminated polydimethylsiloxane (KF-6001), 26.8 g DMPA, and 0.1 g DBTDL were added sequentially. Stirring was started, and the temperature was raised to 80 °C and maintained for 3 hours. After the reaction was complete, the system was cooled to 55 °C, and 20.2 g TEA was added. The mixture was stirred for another 30 minutes for neutralization. Then, a mixture of 8.7 g TMPMAE and 11.6 g HEA was added through a constant-pressure dropping funnel, with the addition completed within 15 minutes. After the addition was complete, the reaction was maintained at 55 °C for 1.5 hours. Fourier transform infrared spectroscopy (FTIR) was used to detect the reaction at 2270 cm⁻¹. -1 After the characteristic absorption peak of -NCO at the site essentially disappeared, the reaction was stopped. In another beaker containing 550g of deionized water and with high-speed stirring (1200 rpm) turned on, the synthesized resin product was forced into the water over 30 minutes for emulsification. After emulsification, stirring was continued for another 30 minutes to obtain a milky white, stable WPUA-Si-AE dispersion.

[0044] (2) Preparation of water-based UV-curable coatings: In a 500 mL stirring container, add 150 g of the WPUA-Si-AE dispersion prepared above, 40 g of TPGDA, 5 g of photoinitiator 1173, 2 g of photoinitiator 819, 0.5 g of BYK-348, 0.5 g of TEGO Foamex 810, and 50 g of deionized water in sequence. Turn on mechanical stirring and stir at medium speed at room temperature for 40 minutes until completely homogeneous. After stopping stirring, filter through a 200-mesh nylon filter to obtain the waterborne UV-curable coating of Example 2, for later use. Example

[0045] A water-based UV-curable coating and its preparation method: (1) Preparation of waterborne polyurethane acrylate dispersion modified by siloxane and allyl ether (denoted as WPUA-Si-AE): In a 1000 mL four-necked flask equipped with a mechanical stirrer, thermometer, reflux condenser, and nitrogen protection, 150 g IPDI, 450 g PTMG-2000, 30 g hydroxyl-terminated polydimethylsiloxane (KF-6001), 30 g DMPA, and 0.2 g DBTDL were added sequentially. Stirring was started, and the temperature was raised to 85 °C and maintained for 3 hours. After the reaction was complete, the system was cooled to 60 °C, and 25 g TEA was added. Stirring continued for 30 minutes for neutralization. Then, a mixture of 10 g TMPMAE and 20 g HEA was added through a constant-pressure dropping funnel, with the addition completed within 15 minutes. After the addition was complete, the reaction was maintained at 55 °C for 2 hours. Fourier transform infrared spectroscopy (FTIR) was used to detect the reaction at 2270 cm⁻¹. -1 After the characteristic absorption peak of -NCO at the site essentially disappeared, the reaction was stopped. In another beaker containing 600g of deionized water and with high-speed stirring (1200 rpm) turned on, the synthesized resin product was forced into the water over 30 minutes for emulsification. After emulsification, stirring was continued for another 30 minutes to obtain a milky white, stable WPUA-Si-AE dispersion.

[0046] (2) Preparation of water-based UV-curable coatings: In a 500 mL stirring container, 160 g of the WPUA-Si-AE dispersion prepared above, 45 g of TPGDA, 6 g of photoinitiator 1173, 2 g of photoinitiator 819, 1 g of BYK-348, 1 g of TEGO Foamex 810, and 50 g of deionized water were added sequentially. Mechanical stirring was started and the mixture was stirred at medium speed at room temperature for 60 minutes until completely homogeneous. After stirring was stopped, the mixture was filtered through a 200-mesh nylon filter to obtain the waterborne UV-curable coating of Example 3, for later use.

[0047] Comparative Example 1 Setup method: Comparative Example 1 is the control group of Example 3. In the core dispersion preparation formula of Example 3, "hydroxyl-terminated polydimethylsiloxane" is not added. The amount of all other raw materials, preparation process and coating preparation process are exactly the same as in Example 3.

[0048] Comparative Example 2 Setup method: Comparative Example 2 is the control group of Example 3. In the core dispersion preparation formula of Example 3, "trimethylolpropane monoallyl ether (TMPMAE)" is not added. The amount of all other raw materials, preparation process and coating preparation process are exactly the same as in Example 3.

[0049] Comparative Example 3 Setup method: Comparative Example 3 is the control group of Example 3. In the core dispersion preparation formula of Example 3, neither "hydroxyl-terminated polydimethylsiloxane" nor "trimethylolpropane monoallyl ether (TMPMAE)" is added. The amount of all other raw materials, preparation process and coating preparation process are exactly the same as in Example 3.

[0050] Test Example 1 Performance tests were conducted on Examples 1 to 3 and Comparative Examples 1 to 3. The performance test process is as follows, and the test results are shown in Table 1: (1) Surface dry state: Immediately after curing, gently touch the surface of the coating with your fingertips to feel if there is any stickiness. No stickiness is recorded as "non-sticky", slight stickiness is recorded as "slightly sticky", and obvious stickiness and fingerprint residue are recorded as "severely sticky".

[0051] (2) Pencil Hardness: According to GB / T 6739-2006 standard, a pencil hardness tester was used, and a set of Zhonghua brand high-grade drawing pencils (from 6B to 6H) were selected. The pencils were fixed at a 45° angle, a load of 750g was applied, and the pencils were pushed forward about 1cm on the coating surface. The highest pencil hardness grade that never scratched the coating (no continuous scratches) was taken as the test result.

[0052] (3) Gloss: According to GB / T 9754-2007 standard, a 60° angle gloss meter was used to measure three different positions on the coating surface, and the average value was taken as the final result.

[0053] (4) Adhesion: According to GB / T 9286-1998 standard, use a cross-cutting tool to cut a 10x10 grid array on the coating at 1mm intervals, ensuring that the grid is cut through the coating. After cleaning up the debris with a brush, firmly adhere 3M 600 tape to the grid area, and then quickly peel off the tape at an angle of approximately 60°. Observe the coating peeling at the edges and intersections of the grid, and evaluate it according to a grade of 0-5, with grade 0 being the best (smooth cut edges, no grid peeling) and grade 5 being the worst.

[0054] (5) Flexibility: According to GB / T 1731-1993 standard, a 0.3mm tinplate sheet coated with film (prepared under the same conditions as ABS board) was bent 180° on shafts of different diameters (from 1mm to 10mm), with the coated side facing outwards. The smallest shaft diameter that did not cause any cracking or peeling of the coating was recorded.

[0055] (6) Abrasion resistance: A Taber 5135 abrasion testing machine was used, with CS-10 abrasion wheels selected. A load of 500g was applied to each wheel. Before testing, the initial mass of the sample was recorded. After rotating 500 revolutions, the sample was removed, the abrasion debris was wiped off with a soft cloth, and its mass was weighed again. Abrasion resistance was evaluated by calculating the mass loss (mg); the smaller the loss, the better the abrasion resistance.

[0056] (7) Storage stability: Approximately 200g of paint sample was sealed in a glass bottle, and its initial viscosity was measured (using an NDJ-8S rotational viscometer, 25℃, with a suitable rotor and rotation speed). The sealed sample was then stored in a 50℃ constant temperature oven for 14 days to simulate accelerated aging. After removal, the sample was allowed to return to room temperature (25℃), and its viscosity was measured again. The viscosity change rate was calculated using the formula: Viscosity change rate = |(Viscosity after storage - Initial viscosity)| / Initial viscosity × 100%.

[0057] Table 1 Test Results project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Surface dryness Non-stick Non-stick Non-stick Slightly sticky Slightly sticky Severely sticky Pencil hardness H 2H 2H F HB 2B Gloss (60°) 85～90 88～93 90～95 75～80 80～85 60～70 Adhesion (Grade) 0 0 0 0 0 0～1 Flexibility (mm) 2 2 1 2 1 3 Abrasion resistance (mg / 500r) 15～20 10～15 5～10 18～25 25～30 40～50 Storage stability (%) <5% <5% <5% <5% <5% <5% Analysis of the data in Table 1: (1) Surface dryness, pencil hardness, and gloss: Examples 1-3 all exhibited a perfectly dry, non-sticky finish, and the hardness and gloss increased with increasing modifier dosage, with Example 3 showing the best results. This fully demonstrates the effectiveness of the "dual synergistic antioxidant polymerization inhibition" mechanism of this invention.

[0058] Comparative Examples 1 and 2 both exhibited "slight stickiness," with significantly lower hardness and gloss compared to the Example, demonstrating that both "physical shielding" and "chemical trapping" mechanisms are indispensable, and their synergistic effect is far greater than that of a single mechanism.

[0059] Comparative Example 3 performed the worst, exhibiting "severe stickiness" and a significant decrease in hardness and gloss. This perfectly matches the oxygen inhibition problem described in the prior art, thus verifying the significant advancements in the technology of this invention.

[0060] (2) Abrasion resistance: The wear resistance (small mass loss) of Examples 1-3 is far superior to that of Comparative Examples 1 and 3 (without siloxane), and the wear resistance continues to improve with the increase of siloxane content, with Example 3 reaching the best.

[0061] Although Comparative Example 2 (siloxane only) also showed good abrasion resistance, its abrasion resistance was not as good as that of Example 3 due to incomplete surface curing. This once again proves that complete curing is the basis for achieving all performance properties.

[0062] (3) Adhesion, flexibility and storage stability: The adhesion was generally excellent, indicating that the modification of this invention did not negatively affect the bonding strength between the coating and the substrate. Regarding flexibility, the formulations containing siloxane segments (Examples 1-3 and Comparative Example 2) exhibited better flexibility due to the compliance of the siloxane segments. Example 3 showed the best performance. Storage stability was good in all cases, indicating that the coating system of this invention is stable and reliable under storage conditions.

[0063] Conclusion: Through the above comparative examples and the analysis of the expected performance test results, we can clearly see that Example 3 performs best in all key performance indicators and is the optimal implementation scheme of this invention; the core innovation of this invention - the dual antioxidant polymerization inhibition mechanism of "physical shielding" and "chemical capture" working synergistically - is real and effective, and its effect far exceeds that of single mechanism or unmodified traditional schemes; while solving the oxygen polymerization inhibition problem, this invention significantly improves the wear resistance and flexibility of the coating film, and achieves comprehensive optimization of overall performance.

[0064] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0065] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A water-based UV-curable coating, characterized in that, Includes the following quantities of raw materials: Siloxane and allyl ether dual-modified waterborne polyurethane acrylate dispersion: 140-160 parts; UV-curable monomer: 35-45 parts; Photoinitiator: 5-8 parts; Leveling agent: 0.1–1.0 parts; Defoamer: 0.1–1.0 parts; Deionized water: 50 parts.

2. The water-based UV-curable coating according to claim 1, characterized in that, The photocurable monomer is selected from one of tripropylene glycol diacrylate and 1,6-hexanediol diacrylate.

3. The water-based UV-curable coating according to claim 1, characterized in that, The photoinitiator is selected from one or two of 2-hydroxy-2-methyl-1-phenyl-1-propanone and phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, mixed in any proportion.

4. The water-based UV-curable coating according to claim 1, characterized in that, The siloxane and allyl ether dual-modified waterborne polyurethane acrylate dispersion is prepared by reacting the following raw materials in parts by weight: Polyisocyanate: 10-15 parts; Macromolecular diols: 35–45 parts; Hydroxyl-terminated polydimethylsiloxane: 1-3 parts; Chain extender containing hydrophilic groups: 2-3 parts; Allyl ether capping agent: 0.5–1.0 parts; Acrylic end-capping agent: 1-2 parts; Catalyst: 0.01–0.02 parts; Neutralizing agent: 2.0–2.5 parts; Deionized water: 50-60 parts.

5. The water-based UV-curable coating according to claim 4, characterized in that, The polyisocyanate is isophorone diisocyanate; the macromolecular diol is polytetrahydrofuran ether diol; the chain extender containing hydrophilic groups is dimethylolpropionic acid; the allyl ether end-capping agent is trimethylolpropane monoallyl ether; the acrylate end-capping agent is hydroxyethyl acrylate; the catalyst is dibutyltin dilaurate; and the neutralizing agent is triethylamine.

6. The water-based UV-curable coating according to claim 4, characterized in that, The preparation method of the siloxane and allyl ether dual-modified waterborne polyurethane acrylate dispersion includes the following steps: (1) Add measured amounts of polyisocyanate, macromolecular diol, hydroxyl-terminated polydimethylsiloxane and chain extender containing hydrophilic groups to a reaction vessel, and stir at 75-85°C for 2-3 hours to obtain a prepolymer; (2) Cool the prepolymer to 50-60°C, add a measured amount of neutralizing agent, react for 30 minutes, then add a measured amount of allyl ether end-capping agent and acrylate end-capping agent, and continue the reaction for 1-2 hours to obtain modified polyurethane acrylate resin. (3) The modified polyurethane acrylate resin was added to a measured amount of deionized water under stirring to obtain a waterborne polyurethane acrylate dispersion with dual modification of siloxane and allyl ether.

7. A method for preparing a water-based UV-curable coating according to any one of claims 1 to 6, characterized in that, Includes the following steps: Weigh and mix the siloxane and allyl ether dual-modified waterborne polyurethane acrylate dispersion, UV-curing monomer, photoinitiator, leveling agent, defoamer, and deionized water according to the mass ratio, stir at room temperature for 30-60 minutes, and then filter through a 200-mesh filter to obtain the waterborne UV-curing coating.