Ultraviolet light-curable ink and method for preparing the same

Abstract

The present application relates to the technical field of wear-resistant ink, in particular to a kind of ultraviolet light-cured ink and preparation method thereof.The present application overcomes the problem of poor adhesion and wear resistance of ultraviolet light-cured ink.The present application prepares carboxylated polyurethane acrylate, which forms high cross-linking density interpenetrating network with epoxy acrylate and ethoxylated trimethylolpropane triacrylate, to improve the adhesion of ink;Preparation of bifunctional fluorinated acrylate and siloxane-acrylic block copolymer monomer, the lubricity of fluorinated layer and the elastic deformation of siloxane synergistically improve the wear resistance of ink;TiO2 sol is coated on mica and modified with epoxy group, and cooperates with silica aerogel and alumina nanowire to form a multi-level wear-resistant mechanism;Preparation of polyurethane-acrylate microcapsule-encapsulated photoinitiator, cooperates with nano-ZnO to scatter ultraviolet light, so that the cross-linked network has continuous high-density structure, and the adhesion and wear resistance of ink are improved.

Description

Technical Field

[0001] This invention relates to the field of wear-resistant ink technology, specifically to an ultraviolet-curable ink and its preparation method. Background Technology

[0002] With the rapid development of the printing industry, the performance requirements for inks are becoming increasingly stringent. Traditional inks present numerous problems during use. For example, solvent-based inks release large amounts of volatile organic compounds during drying, polluting the environment and posing health risks to operators. While water-based inks offer improved environmental friendliness, their slow drying speed leads to low printing efficiency. Ultraviolet (UV) curing inks, on the other hand, have gained widespread application in the printing field due to their advantages such as fast drying speed, short curing time, low energy consumption, and environmental friendliness.

[0003] However, existing UV-curable inks still present some problems when applied to automotive window glass. Firstly, the adhesion between the ink and the substrate is insufficient. When printed on surfaces of different materials such as plastic and metal, the ink struggles to adhere firmly due to the differences in physicochemical properties between the ink and the substrate, easily leading to peeling and flaking, severely affecting the quality of the printed product. Secondly, the poor abrasion resistance of the ink further limits its application. During the use of printed products, they are frequently subjected to external forces such as friction and scratching, and existing UV-curable inks perform poorly in terms of abrasion resistance. Therefore, developing a UV-curable ink with good adhesion and abrasion resistance is of significant practical importance.

[0004] To address this, a UV-curable ink and its preparation method are proposed. Summary of the Invention

[0005] The present invention aims to provide an ultraviolet-curable ink and its preparation method. The method involves preparing a carboxylated polyurethane acrylate, which forms a high-density interpenetrating network with epoxy acrylate and ethoxylated trimethylolpropane triacrylate, thereby improving ink adhesion. Furthermore, the method involves preparing a bifunctional fluorinated acrylate and a siloxane-acrylic block copolymer, where the lubricity of the fluorinated layer and the elastic deformation of the siloxane synergistically enhance the ink's abrasion resistance. Additionally, the method involves coating mica with TiO2 sol and modifying it with epoxy groups, synergistically forming a multi-level anti-abrasion mechanism with silica aerogel and alumina nanowires. Finally, the method involves preparing a photoinitiator encapsulated in polyurethane-acrylate microcapsules, which synergistically scatters ultraviolet light with nano-ZnO, giving the crosslinked network a continuous high-density structure, thus improving ink adhesion and abrasion resistance.

[0006] To achieve the above objectives, the present invention provides the following technical solution: It should be noted that all parts in this invention are parts by weight.

[0007] This invention provides a method for preparing ultraviolet-curable ink, the method being as follows: Carboxylated polyurethane acrylate, epoxy acrylate, and half the total amount of ethoxylated trimethylolpropane triacrylate are added to a reaction vessel and stirred at 200 rpm for 30 min. The mixture is then heated to 60°C and held at that temperature for 10 min. The carboxyl groups and epoxy groups undergo a ring-opening reaction to form a preliminary cross-linking network, improving the compatibility of the resin system. The mixture is then cooled to room temperature to obtain a pre-reacted resin. The remaining ethoxylated trimethylolpropane triacrylate, difunctional fluorinated acrylate, and siloxane-acrylic block copolymer are mixed, and double-coated mica and alumina nanowires are added to further enhance the resin's properties. The mixture was treated with a high-shear disperser for 15 min to bond the epoxy-modified mica with the siloxane segments of the siloxane-acrylic block copolymer monomer. Then, silica aerogel was added in three batches, each 5 min apart, and dispersed with pulsed ultrasonic assistance for 20 min. Nano zinc oxide was added and the dispersion was continued until the fineness was ≤5 μm to obtain a mixture. The pre-reacted resin was mixed with the mixture, and a portion of the microcapsule photoinitiator was added. The mixture was stirred at 800 rpm for 10 min. The remaining microcapsule photoinitiator was mixed with the defoamer and added to the system. The mixture was homogenized at 1200 rpm for 15 min under vacuum. Finally, a leveling agent was added and the mixture was stirred at 600 rpm for 5 min to obtain the ink. Bifunctional fluorinated acrylates are prepared from perfluorohexyl ethanol and acryloyl chloride; Double-coated mica was prepared from mica, tetrabutyl titanate and silane coupling agent; The microcapsule photoinitiator was prepared from a photoinitiator, a polyurethane prepolymer, and methyl methacrylate.

[0008] The preferred method for preparing bifunctional fluorinated acrylate is as follows: A three-necked flask is evacuated and purged with nitrogen three times. 8-15 parts of perfluorohexylethanol and 60 parts of tetrahydrofuran are added and stirred to obtain a mixture. 22 parts of acryloyl chloride and 22 parts of anhydrous triethylamine are added separately to a constant-pressure dropping funnel and simultaneously added dropwise to the mixture at a rate of 5 mL / min, while the system temperature is controlled at 0-5℃ using a low-temperature circulating bath. After the addition is complete, the low-temperature circulating bath is turned off, and the mixture is allowed to naturally rise to 25℃ and stirred continuously for 6-10 hours. The triethylamine hydrochloride precipitate is removed by vacuum filtration. The filtrate is washed three times with 5wt% sodium bicarbonate solution and then washed with deionized water until neutral. Anhydrous magnesium sulfate is added, and after drying, the mixture is rotary evaporated to obtain the bifunctional fluorinated acrylate.

[0009] Preferably, the preparation method of carboxylated polyurethane acrylate is as follows: 50 parts of hexafunctional aliphatic polyurethane acrylate and 5 parts of acrylic acid are added to a reaction vessel, 30 parts of ethyl acetate are added as solvent, and 0.8 parts of n-dodecyl mercaptan are added, and nitrogen gas is introduced for protection; 0.5 parts of azobisisobutyronitrile are added, and the mixture is stirred and reacted at 80°C for 2-4 hours. After the reaction is completed, the solvent and unreacted monomers are removed by vacuum distillation to obtain carboxylated polyurethane acrylate with a viscosity of 1200 mPa·s.

[0010] Preferably, the preparation method of the siloxane-acrylic acid block comonomer is as follows: mercapto-modified polydimethylsiloxane, methyl methacrylate and hydroxyethyl acrylate are mixed in a mass ratio of 1:3-6:1.5-2.5; azobisisobutyronitrile is added, and the mixture is reacted at 70°C for 6 hours to obtain the siloxane-acrylic acid block comonomer.

[0011] The preferred method for preparing double-coated mica is as follows: Mica (commercially available synthetic mica) is dispersed in isopropanol and ultrasonically treated for 20 min; tetrabutyl titanate and nitric acid (to adjust pH=3) are added, and the mixture is hydrolyzed and stirred at 60°C for 2 h, then centrifuged and dried to obtain titanium dioxide-coated mica; the amount of tetrabutyl titanate is 3%-7% of the mica mass; silane coupling agent KH580 is dissolved in ethanol solution to obtain a silane coupling agent solution, and the silane coupling agent solution is mixed with titanium dioxide-coated mica at a mass ratio of 1:3-7, refluxed at 80°C for 4 h, filtered, washed, and dried to obtain double-coated mica with epoxy groups on the surface.

[0012] Preferably, the preparation method of the microcapsule photoinitiator is as follows: 30 parts of 819 photoinitiator and 20 parts of polyurethane prepolymer are mixed at 300 rpm for 15 min to form a core material; 1.5 parts of sodium dodecyl sulfate emulsifier are added to 250 parts of deionized water and stirred to obtain an aqueous phase; the core material is emulsified and dispersed in the aqueous phase and stirred at 750 rpm for 30-40 min; 12 parts of methyl methacrylate and 1.5-4 parts of pentaerythritol tetraacrylate are added; 0.3 parts of azobisisobutyronitrile are added; after purging with nitrogen to remove oxygen, the temperature is raised to 65℃ and stirred in the dark for 5 h. During this process, the wall material monomers polymerize under the action of the thermal initiator to form a dense shell layer, while the 819 photoinitiator in the core material (with good thermal stability) remains active and is not consumed. Finally, the microcapsule photoinitiator is obtained by filtration and drying.

[0013] Preferably, 60% of the total amount of microcapsule photoinitiator is added in the first addition and the remaining 40% is added in the second addition.

[0014] Another aspect of the present invention provides a UV-curable ink, wherein the raw materials for ink production include 35-45 parts of carboxylated polyurethane acrylate, 15-20 parts of epoxy acrylate, 12-18 parts of ethoxylated trimethylolpropane triacrylate, 2-6 parts of difunctional fluorinated acrylate, 3-8 parts of siloxane-acrylic block copolymer monomer, 4-7 parts of double-coated mica, 2 parts of alumina nanowires, 2-5 parts of silica aerogel, 0.5-1.3 parts of nano zinc oxide, 4-9 parts of microencapsulated photoinitiator, 0.9 parts of leveling agent, and 0.5 parts of defoamer; the UV-curable ink is prepared by any of the above preparation methods.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In the pre-reaction stage, the carboxyl groups in the carboxylated polyurethane acrylate undergo an in-situ ring-opening reaction with the epoxy groups in the epoxy acrylate to form ester bonds, creating a preliminary cross-linked network. Simultaneously, half the amount of ethoxylated trimethylolpropane triacrylate is added as a "bridging unit," with its triacrylate groups partially integrating into the carboxyl-epoxy network via free radical reactions, forming an interpenetrating network with a higher pre-crosslinking density. The early intervention of ethoxylated trimethylolpropane triacrylate in this stage not only increases the viscosity of the resin system but also provides more active crosslinking sites for subsequent curing. During final UV curing, the unreacted ethoxylated trimethylolpropane triacrylate further reacts with the hydroxyl groups on the substrate surface, synergistically forming a three-dimensional anchoring structure with the carboxyl and epoxy groups in the pre-crosslinked network, ensuring long-lasting adhesion of the ink to the substrate.

[0016] 2. In this invention, the bifunctional fluorinated acrylate undergoes directional migration to the coating surface during curing due to the low surface energy of the fluorocarbon segments, forming a dense fluorinated protective layer. This layer reduces the coefficient of friction through the strong cohesive force of the fluorine-fluorine segments and blocks the penetration and erosion of the coating by media such as water and oil. On the other hand, in the microphase separation structure of the hard and soft segments of the siloxane-acrylic block copolymer monomer, the hard acrylic segments provide rigid support, while the soft siloxane segments buffer mechanical impact through the extensibility of the molecular chain segments. The synergistic effect of the lubricity of the fluorinated layer and the elastic deformation of the siloxane ensures high resistance to scratching on the ink surface and avoids overall brittle cracking, thereby achieving long-term wear resistance.

[0017] 3. In this invention, the double-coated mica utilizes an epoxy-based silane layer that chemically couples with the siloxane segments in the siloxane-acrylic block copolymer monomer. This molecular-level "bridging" effect tightly binds the rigid mica particles to the flexible resin matrix, forming a highly efficient stress transfer network. Simultaneously, silica aerogel and alumina nanowires are dispersed by pulsed ultrasonication to form a nanoscale microskeleton, absorbing and dispersing the energy generated by external mechanical friction. During friction, the rigid filler bears the principal stress, the flexible siloxane layer dissipates energy through molecular chain slippage, and the nanowires absorb energy through their own bending and breakage, forming a multi-level anti-wear mechanism.

[0018] 4. The photoinitiator wall material encapsulated in the polyurethane-acrylate microcapsules of this invention is polymerized from methyl methacrylate and pentaerythritol tetraacrylate, and has a highly cross-linked structure. In synergy with the double-coated mica and siloxane-acrylic block copolymer monomers, a dense network structure is formed during ink curing, which improves hardness and abrasion resistance. Moreover, the microcapsule structure can control the slow release of photoinitiators, making the polymerization reaction more complete, promoting the chemical bonding and physical entanglement between the ink and the substrate surface, significantly improving the adhesion strength, and effectively solving the problems of insufficient adhesion and poor abrasion resistance of traditional inks. Attached Figure Description

[0019] Figure 1 The figures show the wear resistance test results of Examples 4, 6-8 and Comparative Examples 8-12 of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0021] Please see Figure 1 This invention provides an ultraviolet-curable ink and its preparation method, the technical solution of which is as follows: The material information involved in this invention is as follows: Ethoxylated trimethylolpropane triacrylate CAS: 28961-43-5; Polyurethane prepolymer CAS: 103837-45-2; Perfluorohexylethanol CAS: 647-42-7; Acryloyl chloride CAS: 814-68-6; Acrylic acid CAS: 79-10-7; Azobisisobutyronitrile CAS: 78-67-1; Methyl methacrylate CAS: 80-62-6; Hydroxyethyl acrylate CAS: 818-61-1; Tetratitanate Butyl ester CAS: 5593-70-4; Silane coupling agent KH580 CAS: 14814-09-6; Sodium dodecyl sulfate CAS: 151-21-3; Pentaerythritol tetraacrylate CAS: 4986-89-4; 819 photoinitiator CAS: 162881-26-7; n-Dodecyl mercaptan CAS: 112-55-0; Synthetic mica purchased from Beijing Bairui Biotechnology Co., Ltd.; Epoxy acrylate model: ETERCURE 6210G; Hexafunctional aliphatic polyurethane acrylate model: ETERCURE 6145-100; Alumina nanowires purchased from Beijing Bailingwei Technology Co., Ltd.; Carbon black purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; Thiol-modified polydimethylsiloxane grade: X-22-167B.

[0022] Example 1 35 parts of carboxylated polyurethane acrylate, 15 parts of epoxy acrylate, and half the total amount of ethoxylated trimethylolpropane triacrylate were added to a reactor and stirred at 200 rpm for 30 min. The mixture was then heated to 60°C and held at that temperature for 10 min, and cooled to room temperature to obtain a pre-reacted resin. The remaining ethoxylated trimethylolpropane triacrylate, 2 parts of difunctional fluorinated acrylate, and 3 parts of siloxane-acrylic block copolymer were mixed together, and 4 parts of double-coated mica, 2 parts of alumina nanowires, and 4.5 parts of pigment carbon black were added. The mixture was treated with a high-shear disperser (5000 rpm) for 15 min, and then added in three portions. Two parts of silica aerogel were dispersed for 20 minutes with pulsed ultrasound (20 kHz, 5 s on / 2 s off) at 5-minute intervals. 0.5 parts of nano-zinc oxide were added, and dispersion continued until the fineness was ≤5 μm to obtain a mixture. The pre-reacted resin was mixed with the mixture, and 60% of the total amount of microcapsule photoinitiator was added. The mixture was stirred at 800 rpm for 10 minutes. The remaining 40% of the microcapsule photoinitiator was mixed with BD-FT50 fluorinated defoamer and added to the system. The mixture was homogenized at 1200 rpm for 15 minutes under vacuum (-0.08 MPa). Finally, polyether-modified silicone leveling agent BETTERSOL 3675 was added, and the mixture was stirred at 600 rpm for 5 minutes to obtain the ink. The total amount of ethoxylated trimethylolpropane triacrylate was 12 parts, and the total amount of microcapsule photoinitiator was 4 parts.

[0023] The preparation method of carboxylated polyurethane acrylate is as follows: 50 parts of hexafunctional aliphatic polyurethane acrylate and 5 parts of acrylic acid are added to a reaction vessel, 30 parts of ethyl acetate are added as solvent, and 0.8 parts of n-dodecyl mercaptan are added. Nitrogen gas is introduced for protection. 0.5 parts of azobisisobutyronitrile are added, and the mixture is stirred at 80°C for 2 hours. After the reaction is completed, the solvent and unreacted monomers are removed by vacuum distillation to obtain carboxylated polyurethane acrylate with a viscosity of 1200 mPa·s.

[0024] The preparation method of bifunctional fluorinated acrylate is as follows: A three-necked flask was evacuated and purged with nitrogen three times. 8 parts of perfluorohexylethanol and 60 parts of tetrahydrofuran were added and stirred to obtain a mixture. 22 parts of acryloyl chloride and 22 parts of anhydrous triethylamine were added separately to a constant-pressure dropping funnel and simultaneously added dropwise to the mixture at a rate of 5 mL / min, while the system temperature was controlled at 0-5℃ using a low-temperature circulating bath. After the addition was complete, the low-temperature circulating bath was turned off, and the mixture was allowed to naturally rise to 25℃ and stirred continuously for 6 hours. The triethylamine hydrochloride precipitate was removed by vacuum filtration. The filtrate was washed three times with 5wt% sodium bicarbonate solution and then washed with deionized water until neutral. Anhydrous magnesium sulfate was added, and the mixture was dried and then rotary evaporated to obtain the bifunctional fluorinated acrylate.

[0025] The preparation method of siloxane-acrylic acid block comonomer is as follows: Thiol-modified polydimethylsiloxane, methyl methacrylate, and hydroxyethyl acrylate are mixed in a mass ratio of 1:3:1.5; azobisisobutyronitrile (0.1 wt% of the total amount of thiol-modified polydimethylsiloxane, methyl methacrylate, and hydroxyethyl acrylate) is added, and the mixture is reacted at 70℃ for 6 h to obtain siloxane-acrylic acid block comonomer (functionality ≥2); the amount of thiol-modified polydimethylsiloxane used is 10 parts.

[0026] The preparation method of double-coated mica is as follows: Mica (particle size 10-50 μm) is dispersed in isopropanol (solid-liquid ratio 1:10) and ultrasonically treated for 20 min; tetrabutyl titanate and nitric acid (adjust pH=3) are added, and the mixture is hydrolyzed and stirred at 60℃ for 2 h, then centrifuged and dried to obtain titanium dioxide-coated mica; the amount of tetrabutyl titanate is 3% of the mass of mica; silane coupling agent KH580 (5% of the mass of ethanol) is dissolved in ethanol solution and mixed with titanium dioxide-coated mica at a mass ratio of 1:3, and refluxed at 80℃ for 4 h, filtered, washed and dried to obtain double-coated mica with epoxy groups on the surface; the amount of mica used is 10 parts.

[0027] The preparation method of microcapsule photoinitiator is as follows: 30 parts of 819 photoinitiator and 20 parts of polyurethane prepolymer are mixed at 300 rpm for 15 min to form the core material; 1.5 parts of emulsifier sodium dodecyl sulfate are added to 250 parts of deionized water and stirred to obtain an aqueous phase; the core material is emulsified and dispersed in the aqueous phase and stirred at 750 rpm for 30 min; 12 parts of methyl methacrylate and 1.5 parts of pentaerythritol tetraacrylate are added; 0.3 parts of azobisisobutyronitrile are added; after purging with nitrogen to remove oxygen, the temperature is raised to 65℃ and stirred for 5 h in the dark; finally, the mixture is filtered and dried to obtain the microcapsule photoinitiator.

[0028] Example 2-3 The preparation method and parameters of Example 1 are as follows, with specific differences shown in Table 1; the time in Table 1 is the stirring time when preparing carboxylated polyurethane acrylate.

[0029] Comparative Example 1 The preparation method and parameters were the same as in Example 1, except that epoxy acrylate was not added.

[0030] Comparative Example 2 The preparation method and parameters were the same as in Example 1, except that ethoxylated trimethylolpropane triacrylate was not added.

[0031] Comparative Example 3 The preparation method and parameters were the same as in Example 1, except that no carboxylated polyurethane acrylate was added.

[0032] Comparative Example 4 The preparation method and parameters of Example 1 were used, except that the polyurethane acrylate was not modified by carboxylation.

[0033] Comparative Example 5 The preparation method and parameters of Example 1 are the same, except that ethoxylated trimethylolpropane triacrylate was not added when preparing the pre-reaction resin, but was added all at once when preparing the mixture.

[0034] Experiment Example 1 Adhesion Test The ink was printed on a glass substrate and its performance was tested. The adhesion was tested according to the ISO 2409 standard. The higher the grade, the more severe the peeling and the worse the adhesion. The results are shown in Table 1.

[0035] Table 1 Adhesion tests of Examples 1-3 and Comparative Examples 1-5 As shown in Table 1, in Examples 1-3, during the pre-reaction stage, the carboxyl groups in the carboxylated polyurethane acrylate react with the epoxy groups in the epoxy acrylate in situ to form ester bonds, creating a preliminary cross-linked network. Simultaneously, half of the total amount of ethoxylated trimethylolpropane triacrylate is added as a "bridging unit," with its triacrylate groups partially integrated into the carboxyl-epoxy network via free radical reactions, forming an interpenetrating network with a higher pre-crosslinking density. The early intervention of ethoxylated trimethylolpropane triacrylate in this stage not only increases the viscosity of the resin system but also provides more active crosslinking sites for subsequent curing. During final UV curing, the unreacted ethoxylated trimethylolpropane triacrylate further reacts with the hydroxyl groups on the substrate surface, synergistically forming a three-dimensional anchoring structure with the carboxyl and epoxy groups in the pre-crosslinked network, ensuring long-term adhesion of the ink to the substrate. In all examples, the adhesion was grade 0, and no detachment was observed during adhesion testing. In Comparative Example 1, without the addition of epoxy acrylate, the pre-crosslinking structure could not be formed, leading to decreased resin system compatibility and a significant reduction in the proportion of interfacial chemical bonds. Simultaneously, unreacted carboxyl groups were unable to effectively bond with the substrate through subsequent curing, resulting in decreased adhesion. Ethoxylated trimethylolpropane triacrylate, as a trifunctional crosslinking monomer, was added in stages to precisely control the crosslinking density. In the first step, half of the ethoxylated trimethylolpropane triacrylate was added to form an interpenetrating structure with the carboxyl-epoxy network during the pre-reaction, increasing the resin system viscosity and anchoring point density. The remaining portion reacted with the hydroxyl groups of the substrate during the curing stage to strengthen interfacial bonding. In Comparative Example 2, without the addition of ethoxylated trimethylolpropane triacrylate, the system crosslinking relied solely on the ring-opening reaction between carboxyl and epoxy groups, resulting in insufficient crosslinking density, a loose network, weakened physical anchoring of the coating, and a reduction in interfacial chemical bonding sites, leading to decreased adhesion. Carboxylated polyurethane acrylate is the core of the pre-crosslinked network. Its carboxyl groups not only participate in the ring-opening reaction of epoxy groups, but also provide a large number of carboxyl-hydroxyl / amino chemical bonding sites for the ink and the substrate. In Comparative Example 3, without the addition of carboxylated polyurethane acrylate, the pre-reaction lacked an initiating crosslinking agent, and the epoxy acrylate could not effectively form a network, resulting in a severe deterioration in the compatibility of the resin system. In addition, the ink and the substrate lost the chemical bonding ability of the carboxyl groups, and the adhesion decreased. In Comparative Example 4, without carboxylation modification of the polyurethane acrylate, it could not undergo a pre-crosslinking reaction with the epoxy acrylate, resulting in a simple physical mixing state of the resin system. Although the polyurethane segments have a certain degree of flexibility, the low crosslinking density resulted in insufficient rigid support of the coating and the inability to form high-strength chemical bonds with the substrate.In Comparative Example 5, ethoxylated trimethylolpropane triacrylate was not added during the preparation of the pre-reaction resin, but was added all at once during the preparation of the mixture. The pre-reaction stage lacked sufficient crosslinking monomers, the carboxyl-epoxy network was loose, and a large amount of ethoxylated trimethylolpropane triacrylate was concentrated in the curing stage, resulting in uneven distribution of functional groups during resin polymerization, coexistence of local over-crosslinking and low-crosslinking regions, destruction of the overall network continuity, and a decrease in the interfacial chemical anchoring ability.

[0036] Examples 4-5 The preparation method and parameters of Example 2 are as follows, with specific differences shown in Table 2. In Table 2, the time is the stirring time after the low-temperature circulating bath is turned off when preparing the difunctional fluorinated acrylate. The mass ratio of the three is the mass ratio of polydimethylsiloxane, methyl methacrylate and hydroxyethyl acrylate.

[0037] Comparative Example 6 The preparation method and parameters were the same as in Example 2, except that no bifunctional fluorinated acrylate was added.

[0038] Comparative Example 7 The preparation method and parameters of Example 2 are the same, except that no siloxane-acrylic acid block copolymer monomer is added.

[0039] Experiment Example 2: Wear Resistance Test The wear resistance was tested according to the method of GMW14688. A five-finger scratch abrasion tester was used to conduct a scratch test on the patterned surface with a force of 10N. The results are shown in Table 2.

[0040] Table 2. Wear resistance test results of Examples 2, 4-5 and Comparative Examples 6-7 As shown in Table 2, in Examples 2 and 4-5, the difunctional fluorinated acrylate migrates directionally to the coating surface during the curing process due to the low surface energy characteristics of the fluorocarbon segments, forming a dense fluorinated protective layer. This layer reduces the coefficient of friction through the strong cohesive force of the fluorine-fluorine segments and blocks the penetration and erosion of the coating by media such as water and oil. On the other hand, in the microphase separation structure of the soft and hard segments of the siloxane-acrylic block copolymer monomer, the hard acrylic segments provide rigid support, while the soft siloxane segments buffer mechanical impact through the extensibility of the molecular chain segments. The synergistic effect of the lubricity of the fluorinated layer and the elastic deformation of the siloxane ensures the high resistance of the ink surface to scratches and avoids overall brittle cracking, thereby achieving long-term wear resistance. In Example 4, the ink exhibited the best abrasion resistance with a wear rate of 1.32 mg when the amount of perfluorohexyl ethanol was 12 parts, the time was 8 hours, the mass ratio of the three components was 1:4:2, the amount of difunctional fluorinated acrylate was 4 parts, and the amount of siloxane-acrylic block copolymer monomer was 5 parts. The directional migration of fluorocarbon chains forms a fluorine-rich layer with a low coefficient of friction on the coating surface, effectively reducing shear stress during friction. In Comparative Example 6, without the addition of difunctional fluorinated acrylate, the surface friction coefficient increased, leading to frictional heat accumulation and accelerated wear rate. Siloxane segments and epoxy groups on the surface of double-coated mica are chemically bonded to form a "rigid filler-flexible interface layer" structure. In Comparative Example 7, without the addition of siloxane-acrylic block copolymer monomer, the mica is only dispersed through physical adsorption, making it prone to aggregation under high shear, resulting in an increase in stress concentration points. Furthermore, without the siloxane interface layer, the filler cannot effectively disperse stress, leading to rapid ink wear.

[0041] Examples 6-8 The preparation method and parameters of Example 4 are as follows, with specific differences shown in Table 3. The mass ratio in Table 3 is the mass ratio of silane coupling agent KH580 dissolved in ethanol solution to titanium dioxide-coated mica when preparing double-coated mica.

[0042] Comparative Example 8 The preparation method and parameters of Example 4 were used, except that alumina nanowires were not added.

[0043] Comparative Example 9 The preparation method and parameters of Example 4 are the same, except that the titanium dioxide-coated mica was not modified with silane coupling agent for epoxy group modification.

[0044] Comparative Example 10 The preparation method and parameters were the same as in Example 4, except that double-coated mica was not added.

[0045] Comparative Example 11 The preparation method and parameters of Example 4 are the same, except that the silica aerogel is added all at once instead of in three separate additions.

[0046] Comparative Example 12 The preparation method and parameters were the same as in Example 4, except that silica aerogel was not added.

[0047] Experiment Example 3: Wear Resistance Test The wear resistance was tested according to the method in Experiment Example 2; the results are shown in Table 3 and... Figure 1 As shown.

[0048] Table 3. Wear resistance test results of Examples 4, 6-8 and Comparative Examples 8-12 From Table 3 and Figure 1 As can be seen, in Examples 4 and 6-8, the double-coated mica chemically couples with the siloxane segments in the siloxane-acrylic block copolymer monomer through the epoxy-siloxane layer. This molecular-level "bridging" effect tightly binds the rigid mica particles to the flexible resin matrix, forming a highly efficient stress transfer network. Simultaneously, the silica aerogel and alumina nanowires are dispersed by pulsed ultrasonication to form a nanoscale microskeleton, absorbing and dispersing the energy generated by external mechanical friction. During friction, the rigid filler bears the principal stress, the flexible siloxane layer dissipates energy through molecular chain slippage, and the nanowires absorb energy through their own bending and fracture, forming a multi-level anti-wear mechanism. In Example 6, when the amount of tetrabutyl titanate is 4.5%, the mass ratio of the two is 1:4, the amount of double-coated mica is 5 parts, and the amount of silica aerogel is 3 parts, the resulting ink exhibits the best wear resistance, with an abrasion amount of 2.20 mg. Nanowires form a three-dimensional network embedded in the resin matrix, effectively intercepting propagating cracks during friction and dissipating energy through their own fracture. In Comparative Example 8, without the addition of alumina nanowires, cracks directly penetrated the matrix, accelerating the formation of wear debris. In Comparative Example 9, the prepared titanium dioxide-coated mica was not modified with epoxy groups, resulting in weak bonding between the titanium dioxide-coated mica and the ink system. Under friction, it easily detached from the ink, failing to effectively enhance wear resistance. In Comparative Example 10, without the addition of double-coated mica, the filler system lost its graded load-bearing capacity, and frictional heat was accelerated to transfer to the matrix, leading to a decrease in wear resistance. In Comparative Example 11, the silica aerogel was added all at once instead of in three stages, resulting in insufficient wetting of the aerogel particles under high-speed shear, forming agglomerates and uneven dispersion. This prevented the formation of a good spatial network structure, thus reducing its effect on improving the wear resistance of the ink. In Comparative Example 12, no silica aerogel was added, resulting in a less dense internal structure of the ink. When subjected to friction, the intermolecular forces were weaker, making it prone to wear.

[0049] Examples 9-10 The preparation method and parameters of Example 6 are as follows, with specific differences shown in Table 4; the time in Table 4 is the stirring time for the core material to be emulsified and dispersed in the aqueous phase when preparing the microcapsule photoinitiator.

[0050] Comparative Example 13 The preparation method and parameters of Example 6 are the same, except that the microcapsule photoinitiator is replaced with 819 photoinitiator.

[0051] Comparative Example 14 The preparation method and parameters were the same as in Example 6, except that no nano zinc oxide was added.

[0052] Comparative Example 15 The preparation method and parameters of Example 6 are the same, except that the microcapsule photoinitiator is not added in batches, but is added all at once after the pre-reaction resin and the mixture are mixed.

[0053] Experiment Example 4: Adhesion and Abrasion Resistance Test The wear resistance was tested according to the methods of Experimental Example 1 and Experimental Example 2; the results are shown in Table 4.

[0054] Table 4 Adhesion and abrasion resistance tests of Examples 6, 9-10 and Comparative Examples 13-14 As shown in Table 4, in Examples 6 and 9-10, the photoinitiator wall material encapsulated in polyurethane-acrylate microcapsules was polymerized from methyl methacrylate and pentaerythritol tetraacrylate, exhibiting a highly cross-linked structure. Synergistically with the double-coated mica and siloxane-acrylate block copolymer monomers, it forms a dense network structure during ink curing, enhancing hardness and abrasion resistance. Furthermore, the microcapsule structure allows for controlled slow release of the photoinitiator, resulting in a more complete polymerization reaction, promoting chemical bonding and physical entanglement between the ink and the substrate surface, significantly improving adhesion strength. In Example 9, when the curing time was 35 min, the amount of pentaerythritol tetraacrylate was 2.5 parts, the amount of microcapsule photoinitiator was 6 parts, and the amount of nano-zinc oxide was 0.9 parts, the resulting ink exhibited the best adhesion and abrasion resistance, with an adhesion grade of 0 and an abrasion amount of 2.10 mg. In Comparative Example 13, the microcapsule photoinitiator was replaced with 819 photoinitiator. 819 photoinitiator has a fast reaction rate, leading to rapid cross-linking of the resin in the early stages of curing. This results in excessive cross-linking of the surface layer and insufficient curing of the deeper layers. Uneven curing causes a weak interface layer to form at the substrate-coating interface, reducing adhesion. Furthermore, the over-cross-linked areas become more brittle and prone to surface cracking, while the under-cured areas undergo plastic deformation during friction, increasing wear debris. ZnO nanoparticles form a chemical adsorption with the substrate through hydroxyl groups. Their rough surface enhances mechanical interlocking, and the hard phase of ZnO can block the invasion of wear particles. In Comparative Example 14, without the addition of nano-zinc oxide, the resulting ink exhibited decreased adhesion and abrasion resistance. In Comparative Example 15, the microcapsule photoinitiator was not added in batches but was added all at once after the pre-reacted resin was mixed with the mixture. This caused localized concentration deviations, and the filler formed agglomeration-sensitive areas due to uneven dispersion. The all-time addition also led to differences in modulus between the surface and interior layers, resulting in step-like peeling during friction.

[0055] 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 method for preparing an ultraviolet-curable ink, characterized in that: The preparation method is as follows: Carboxylated polyurethane acrylate, epoxy acrylate, and ethoxylated trimethylolpropane triacrylate are reacted to obtain a pre-reacted resin; the ethoxylated trimethylolpropane triacrylate, difunctional fluorinated acrylate, and siloxane-acrylic block copolymer monomer are mixed, double-coated mica and alumina nanowires are added and stirred, silica aerogel is added, pulsed ultrasound-assisted dispersion is performed, nano zinc oxide is added to obtain a mixture, which is then mixed with the pre-reacted resin, microcapsule photoinitiator is added, and stirring is performed to obtain the ink; The bifunctional fluorinated acrylate is prepared from perfluorohexyl ethanol and acryloyl chloride; the double-coated mica is prepared from mica, tetrabutyl titanate and silane coupling agent; the microcapsule photoinitiator is prepared from photoinitiator, polyurethane prepolymer and methyl methacrylate.

2. The method for preparing an ultraviolet-curable ink according to claim 1, characterized in that: The preparation method of the bifunctional fluorinated acrylate is as follows: perfluorohexyl ethanol and tetrahydrofuran are added to a three-necked flask to obtain a mixture; acryloyl chloride and anhydrous triethylamine are simultaneously added dropwise to the mixture, and the reaction is continuously stirred to obtain the bifunctional fluorinated acrylate.

3. The method for preparing an ultraviolet-curable ink according to claim 1, characterized in that: The method for preparing the carboxylated polyurethane acrylate is as follows: polyurethane acrylate and acrylic acid are added to a reaction vessel, a solvent and n-dodecyl mercaptan are added, and nitrogen gas is introduced for protection; azobisisobutyronitrile is added, and the reaction is stirred to obtain the carboxylated polyurethane acrylate.

4. The method for preparing an ultraviolet-curable ink according to claim 1, characterized in that: The preparation method of the siloxane-acrylic acid block comonomer is as follows: mercapto-modified polydimethylsiloxane, methyl methacrylate and hydroxyethyl acrylate are mixed, azobisisobutyronitrile is added, and the reaction is carried out to obtain the siloxane-acrylic acid block comonomer.

5. The method for preparing an ultraviolet-curable ink according to claim 1, characterized in that: The method for preparing the double-coated mica is as follows: the mica is dispersed in isopropanol and ultrasonically treated; tetrabutyl titanate and nitric acid are added, hydrolyzed and stirred, and then centrifuged and dried to obtain titanium dioxide-coated mica; the silane coupling agent is dissolved in an ethanol solution to obtain a silane coupling agent solution, and the silane coupling agent solution is mixed with the titanium dioxide-coated mica and reacted to obtain the double-coated mica.

6. The method for preparing an ultraviolet-curable ink according to claim 1, characterized in that: The preparation method of the microcapsule photoinitiator is as follows: the initiator is mixed with the polyurethane prepolymer to obtain a core material; an emulsifier is added to deionized water and stirred to obtain an aqueous phase; the core material is emulsified and dispersed in the aqueous phase and stirred; methyl methacrylate, pentaerythritol tetraacrylate and thermal initiator are added and stirred continuously; the temperature is raised and kept warm; and the microcapsule photoinitiator is obtained by filtration and drying.

7. A UV-curable ink, characterized in that: The raw materials for ink production include carboxylated polyurethane acrylate, epoxy acrylate, ethoxylated trimethylolpropane triacrylate, difunctional fluorinated acrylate, siloxane-acrylic block copolymer monomer, double-coated mica, alumina nanowires, silica aerogel, nano zinc oxide, and microcapsule photoinitiator; the ultraviolet-curable ink is prepared by the preparation method according to any one of claims 1-6.

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