High-adhesiveness water-based printing ink and preparation method thereof

Abstract

The invention discloses high-adhesiveness water-based printing ink and a preparation method thereof, and belongs to the technical field of printing, and the high-adhesiveness water-based printing ink comprises the following components: water-based acrylic resin, SiO2 (at) TiO2 (at) EPS composite filler, pigment, a dynamic covalent cross-linking agent, nano cellulose, a wetting dispersant, a defoaming agent and deionized water. The preparation method comprises the following steps: firstly, preparing an EPS terpolymer containing a multi-functional group, and then modifying a SiO2 / TiO2 preassembly to prepare a composite filler; meanwhile, a dynamic covalent cross-linking agent generated by the reaction of furan methacrylate and maleimide propyl triethoxy silane is prepared; and finally, mixing the components step by step to obtain the ink. The multi-stage structure of the composite filler enhances the interface effect and covering power, the dynamic covalent cross-linking agent forms a reversible network to improve the stability and the self-repairing property, and the nano cellulose and other components have the synergistic effect, so that the ink has good adhesiveness and stability.

Description

Technical Field

[0001] This invention relates to the field of printing technology, specifically to a highly adhesive water-based printing ink and its preparation method. Background Technology

[0002] Water-based printing inks, using water as the primary solvent, are characterized by low volatile organic compound (VOC) emissions and environmental friendliness, and have been widely used in various printing scenarios such as food packaging, pharmaceutical packaging, books and periodicals, plastic films, and paper. With increasingly stringent environmental regulations and rising market demand for green printing, their share in the packaging printing field continues to expand, becoming an important alternative to traditional solvent-based inks, especially in food contact printing where safety requirements are high, where they demonstrate irreplaceable advantages.

[0003] Traditional water-based printing inks typically use water-based resins (such as water-based acrylic resins and water-based polyurethane resins) as the film-forming matrix, combined with pigments to provide color, and fillers to enhance mechanical properties. Wetting and dispersing agents, defoamers, and other additives are also added to improve processing performance. In existing technologies, to improve ink performance, inorganic fillers such as silica and titanium dioxide are often introduced to enhance film hardness, or conventional crosslinking agents such as isocyanate derivatives and epoxy compounds are used to improve film density. However, these fillers often suffer from poor dispersibility and poor compatibility with the resin matrix, and crosslinking agents may also affect ink storage performance due to insufficient reaction stability.

[0004] However, traditional water-based printing inks still have shortcomings in practical applications: on the one hand, they have insufficient adhesion, especially on non-polar substrates such as polyethylene and polypropylene, where the interface between the ink and the substrate is weak, and they are prone to peeling, scratching, and other phenomena; on the other hand, they have limited opacity, and due to the low matching degree of the optical properties of the fillers, the printed matter needs to be overprinted multiple times to achieve the ideal opacity effect. Summary of the Invention

[0005] To address the technical deficiencies in the prior art, this invention proposes a highly adhesive water-based printing ink and its preparation method, solving the aforementioned technical problems and meeting practical needs. The specific technical solution is as follows: A highly adhesive water-based printing ink, by weight, comprises the following components: 50-70 parts water-based acrylic resin, 5-15 parts SiO2@TiO2@EPS composite filler, 10-25 parts pigment, 5-10 parts dynamic covalent crosslinking agent, 3-8 parts nanocellulose, 1-3 parts wetting and dispersing agent, 0.5-1.5 parts defoamer, and 20-35 parts deionized water.

[0006] As a further technical solution of the present invention, the dynamic covalent crosslinking agent is prepared by reacting furan methacrylate with maleimide propyltriethoxysilane in a molar ratio of 1:1.

[0007] As a further technical solution of the present invention, the SiO2@TiO2@EPS composite filler is prepared by the following method: a) Provide porous SiO2 nanospheres and nano-TiO2 particles with a particle size smaller than the pore size of SiO2 nanospheres; b) Load nano-TiO2 particles onto the surface and pores of porous SiO2 nanospheres to form a SiO2@TiO2 pre-assembly; c) The SiO2@TiO2 pre-assembled body is surface modified using EPS terpolymer to obtain the SiO2@TiO2@EPS composite filler; The EPS terpolymer is a random copolymer of glycidyl methacrylate (GMA), phosphate ester functional monomer (EMPA), silane ester functional monomer (MOSi), and styrene (St).

[0008] As a further technical solution of the present invention, the phosphate ester functional monomer is ethyl phosphate methacrylate; the silane ester functional monomer is γ-methacryloyloxypropyltrimethoxysilane.

[0009] As a further technical solution of the present invention, the wetting and dispersing agent is a polyether-modified siloxane dispersant; the defoamer is a mineral oil or organosilicon defoamer; and the nanocellulose is cellulose nanocrystals or cellulose nanofibers obtained by mechanical grinding or acid hydrolysis, with a length of 0.2-2μm and a diameter of 5-50nm.

[0010] A method for preparing a highly adhesive water-based printing ink includes the following steps: S1. Preparation of EPS terpolymer Glycidyl methacrylate, phosphate functional monomers, silane functional monomers and styrene were mixed in a molar ratio of (2-4):(1-3):(0.5-1.5):(3-5), an initiator was added, and a free radical copolymerization reaction was carried out under nitrogen protection. After the reaction, the product was precipitated, washed and dried to obtain EPS terpolymer. S2. Preparation of SiO2@TiO2@EPS composite filler S2.1. Activation treatment of porous SiO2 nanospheres; S2.2. The activated SiO2 nanospheres were mixed with nano-TiO2 particles, and SiO2@TiO2 pre-assembled bodies were obtained by adsorption and calcination. S2.3. The surface of the SiO2@TiO2 pre-assembled body is modified with the EPS terpolymer obtained in step S1 to obtain the SiO2@TiO2@EPS composite filler; S3. Preparation of dynamic covalent crosslinking agents Furan methacrylate and maleimide propyltriethoxysilane were mixed in a molar ratio of 1:1, and a solvent was added to react the mixture. After the solvent was removed, a dynamic covalent crosslinking agent was obtained. S4. Preparation of water-based printing inks Deionized water, wetting and dispersing agent, and part of the defoamer are mixed and dispersed, and pigment and nanocellulose are added to prepare color paste; then water-based acrylic resin, dynamic covalent crosslinking agent, SiO2@TiO2@EPS composite filler and the remaining deionized water are added, mixed evenly, and the remaining defoamer is added, and filtered to obtain ink.

[0011] As a further technical solution of the present invention, in step S1: the initiator is azobisisobutyronitrile (AIBN), accounting for 1-2% of the total mass of the monomer; the reaction conditions are: stirring at 70-80°C for 8-12 hours in isopropanol; the precipitation solvent is n-hexane, and after washing, the product is vacuum dried at 50°C for 24 hours.

[0012] As a further technical solution of the present invention, in step S2.1: porous SiO2 nanospheres are dispersed in deionized water, the pH is adjusted to 9-10 with NaOH, stirred for 2 hours to activate, centrifuged and washed until neutral, and then dried; in step S2.2: SiO2 nanospheres are dispersed in ethanol, nano-TiO2 particles with a particle size of 10-20 nm are added, ultrasonically dispersed for 30 min, the pH is adjusted to 4-5, reacted at 60℃ for 6 hours, centrifuged and washed, and then calcined at 500℃ for 2 hours; in step S2.3: EPS terpolymer is dissolved in ethyl acetate, ultrasonically dispersed with SiO2@TiO2 pre-assembled body, refluxed at 80℃ for 12 hours, centrifuged and washed, and then vacuum dried at 60℃ for 24 hours; and the mass ratio of SiO2 nanospheres to nano-TiO2 is 1:(0.5-2).

[0013] As a further technical solution of the present invention, in step S3: the reaction solvent is tetrahydrofuran, the reaction conditions are stirring at 60-70°C for 4-6 hours under a nitrogen atmosphere, and the solvent is removed by rotary evaporation to obtain a light yellow viscous liquid.

[0014] As a further technical solution of the present invention, the specific steps of step S4 are as follows: First, mix half of the amount of deionized water, wetting and dispersing agent, and half of the amount of defoamer, and stir at 500-800 rpm for 5 minutes. Then add pigment and nanocellulose, and disperse at 2000-2500 rpm for 30-45 minutes. Add waterborne acrylic resin, dynamic covalent crosslinking agent, composite filler, and the remaining deionized water and defoamer at 800-1000 rpm, and stir for 30 minutes. After defoaming, stir at 300-500 rpm for 10 minutes and then filter.

[0015] The beneficial effects of this invention are as follows: This invention utilizes a SiO2@TiO2@EPS composite filler, modified with EPS copolymer through the multi-level structure of SiO2@TiO2, to enhance compatibility with resins and interfacial bonding with non-polar substrates, thus solving the problem of ink detachment. Simultaneously, it optimizes light scattering to improve hiding power and reduce overprinting. A dynamic covalent crosslinking agent forms a dynamic crosslinking network, improving film density and high-temperature self-healing properties, and enhancing storage stability. Nanocellulose enhances mechanical properties, and additives optimize processability. Overall, the ink exhibits excellent adhesion and hiding power, making it suitable for demanding applications. Detailed Implementation

[0016] The embodiments of the present invention will be described below with reference to relevant examples. The embodiments of the present invention are not limited to the following examples, and the present invention relates to relevant necessary components in this technical field, which should be regarded as well-known technology in this technical field and can be known and mastered by those skilled in this technical field.

[0017] A highly adhesive water-based printing ink, by weight, comprises the following components: 50-70 parts water-based acrylic resin, 5-15 parts SiO2@TiO2@EPS composite filler, 10-25 parts pigment, 5-10 parts dynamic covalent crosslinking agent, 3-8 parts nanocellulose, 1-3 parts wetting and dispersing agent, 0.5-1.5 parts defoamer, and 20-35 parts deionized water.

[0018] Furthermore, the dynamic covalent crosslinking agent is prepared by reacting furan methacrylate with maleimide propyltriethoxysilane in a molar ratio of 1:1.

[0019] Furthermore, the wetting and dispersing agent is a polyether-modified siloxane dispersant; the defoamer is a mineral oil or organosilicon defoamer; and the nanocellulose is cellulose nanocrystals or cellulose nanofibers obtained by mechanical grinding or acid hydrolysis, with a length of 0.2-2 μm and a diameter of 5-50 nm.

[0020] This invention uses water-based acrylic resin as a base material to provide the film-forming foundation, forming a continuous phase with other components. The SiO2@TiO2@EPS composite filler consists of porous SiO2 nanospheres loaded with nano-TiO2 to form a multi-level structure, enhancing interfacial interactions. The EPS copolymer contains epoxy groups, phosphate ester groups, siloxane groups, and benzene rings, which not only enhances compatibility with the resin but also improves interfacial adhesion to non-polar substrates through polar groups, solving the problem of peeling. At the same time, the light scattering properties of TiO2 and the porous structure of SiO2 synergistically optimize the hiding power, reducing the need for overprinting.

[0021] The dynamic covalent crosslinking agent is generated by the reaction of furan methacrylate and maleimide propyltriethoxysilane. Its dynamic covalent bonds can form a reversible crosslinking network, which not only improves the film density, but also gives it high-temperature self-healing ability, while improving the storage stability of ink and avoiding delamination.

[0022] Nanocellulose, with its nanoscale properties, synergistically enhances mechanical properties and improves the film's abrasion resistance in conjunction with acrylic resin and fillers. Wetting and dispersing agents ensure uniform dispersion of pigments and fillers, defoamers eliminate processing bubbles, and deionized water adjusts viscosity to optimize processability. The synergistic effect of these components results in inks exhibiting excellent adhesion, hiding power, mechanical properties, and stability, making them suitable for demanding printing applications.

[0023] As one of the preferred embodiments of the present invention, the SiO2@TiO2@EPS composite filler is prepared by the following method: a) Provide porous SiO2 nanospheres and nano-TiO2 particles with a particle size smaller than the pore size of SiO2 nanospheres; b) Load nano-TiO2 particles onto the surface and pores of porous SiO2 nanospheres to form a SiO2@TiO2 pre-assembly; c) The SiO2@TiO2 pre-assembled body is surface modified using EPS terpolymer to obtain the SiO2@TiO2@EPS composite filler; The EPS terpolymer is a random copolymer of glycidyl methacrylate (GMA), phosphate ester functional monomer (EMPA), silane ester functional monomer (MOSi), and styrene (St).

[0024] Furthermore, the phosphate ester functional monomer is ethyl phosphate methacrylate; the silane ester functional monomer is γ-methacryloyloxypropyltrimethoxysilane.

[0025] In the above method for preparing SiO2@TiO2@EPS composite filler, in step a), porous SiO2 nanospheres provide a three-dimensional porous framework. The pore size needs to be larger than the diameter of the nano TiO2 particles to create space conditions for subsequent loading, ensuring that TiO2 can both adhere to the surface and enter the pores to form a three-dimensional distribution.

[0026] Step b) involves loading nano-TiO2 particles onto the surface and pores of SiO2 through adsorption, forming a SiO2@TiO2 pre-assembled structure. This structure combines the porous stability of SiO2 with the light scattering properties of TiO2, providing structural support for the filler and enhancing the ink's hiding power through the optical properties of TiO2.

[0027] In step c), the composite filler is randomly copolymerized from glycidyl methacrylate (GMA), ethyl phosphate methacrylate (EMPA), γ-methacryloyloxypropyltrimethoxysilane (MOSi), and styrene (St). The epoxy groups of GMA react with the substrate to enhance adhesion, the phosphate groups of EMPA provide polar sites to improve interfacial interaction, the silane groups of MOSi react with the hydroxyl groups on the surfaces of SiO2 and TiO2 to achieve a strong bond, and styrene improves compatibility with the resin. Ultimately, through the synergistic effect of multiple functional groups, the composite filler is adapted to both inorganic components and organic resin phases, improving the overall system stability and adhesion performance.

[0028] A method for preparing a highly adhesive water-based printing ink includes the following steps: S1. Preparation of EPS terpolymer Glycidyl methacrylate, phosphate functional monomers, silane functional monomers and styrene were mixed in a molar ratio of (2-4):(1-3):(0.5-1.5):(3-5), an initiator was added, and a free radical copolymerization reaction was carried out under nitrogen protection. After the reaction, the product was precipitated, washed and dried to obtain EPS terpolymer. S2. Preparation of SiO2@TiO2@EPS composite filler S2.1. Activation treatment of porous SiO2 nanospheres; S2.2. The activated SiO2 nanospheres were mixed with nano-TiO2 particles, and SiO2@TiO2 pre-assembled bodies were obtained by adsorption and calcination. S2.3. The surface of the SiO2@TiO2 pre-assembled body is modified with the EPS terpolymer obtained in step S1 to obtain the SiO2@TiO2@EPS composite filler; S3. Preparation of dynamic covalent crosslinking agents Furan methacrylate and maleimide propyltriethoxysilane were mixed in a molar ratio of 1:1, and a solvent was added to react the mixture. After the solvent was removed, a dynamic covalent crosslinking agent was obtained. S4. Preparation of water-based printing inks Deionized water, wetting and dispersing agent, and part of the defoamer are mixed and dispersed, and pigment and nanocellulose are added to prepare color paste; then water-based acrylic resin, dynamic covalent crosslinking agent, SiO2@TiO2@EPS composite filler and the remaining deionized water are added, mixed evenly, and the remaining defoamer is added, and filtered to obtain ink.

[0029] In the above preparation method, step S1 involves free radical copolymerization of monomers in a specific molar ratio to generate an EPS terpolymer. The proportions of epoxy groups, phosphate ester groups, silane ester groups, and benzene rings in this copolymer are well-matched, laying the molecular foundation for subsequent bonding with fillers, resins, and substrates, ensuring synergistic effects of functional groups. Step S2 enhances the surface activity of SiO2 nanospheres through activation treatment, promoting stable loading of TiO2 particles on the surface and pores, and strengthening the bonding force through calcination. Further modification with the EPS copolymer allows the composite filler to possess both the structural support of the inorganic phase and the compatibility of the organic phase, improving its dispersibility in the resin and its interfacial bonding with the substrate. The dynamic covalent crosslinking agent generated in step S3 (1:1 ratio) can form a reversible crosslinking network, endowing the ink with self-healing ability and storage stability after film formation. Step S4, a stepwise mixing process, first ensures uniform dispersion of pigments and nanocellulose, then sequentially adds resin, crosslinking agent, and composite filler, and finally defoaming and filtering to prevent component agglomeration and ensure ink fineness and uniformity. The overall method, through the coordinated efforts of each step, enables the final ink to possess high adhesion, excellent hiding power, good mechanical properties, and storage stability, making it suitable for demanding printing scenarios.

[0030] As one of the preferred embodiments of the present invention, in step S1: the initiator is azobisisobutyronitrile (AIBN), accounting for 1-2% of the total mass of the monomer; the reaction conditions are: stirring at 70-80°C for 8-12 hours in isopropanol; the precipitation solvent is n-hexane, and after washing, the product is vacuum dried at 50°C for 24 hours.

[0031] Azobisisobutyronitrile (AIBN) was selected as the initiator, and its dosage was 1-2% of the total mass of glycidyl methacrylate, phosphate functional monomers, silane functional monomers, and styrene. Isopropanol was used as the solvent, which can effectively dissolve the monomers and ensure that the reaction takes place in a homogeneous system. A temperature of 70-80℃ is suitable for the decomposition characteristics of AIBN, and stirring for 8-12 hours promotes the full copolymerization of monomers to form a copolymer with a uniform structure. Hexane was used as the precipitation solvent, which can efficiently precipitate the copolymer. Washing removes unreacted monomers and impurities, improving purity. Vacuum drying at 50℃ for 24 hours can completely remove the solvent and avoid high temperature damage to the copolymer structure, finally obtaining a pure and stable EPS terpolymer.

[0032] As one of the preferred embodiments of the present invention, in step S2.1: porous SiO2 nanospheres are dispersed in deionized water, the pH is adjusted to 9-10 with NaOH, stirred for 2 hours to activate, centrifuged and washed until neutral, and then dried; in step S2.2: SiO2 nanospheres are dispersed in ethanol, nano-TiO2 particles with a particle size of 10-20 nm are added, ultrasonically dispersed for 30 min, the pH is adjusted to 4-5, reacted at 60℃ for 6 hours, centrifuged and washed, and then calcined at 500℃ for 2 hours; in step S2.3: EPS terpolymer is dissolved in ethyl acetate, ultrasonically dispersed with SiO2@TiO2 pre-assembled body, refluxed at 80℃ for 12 hours, centrifuged and washed, and then vacuum dried at 60℃ for 24 hours; and the mass ratio of SiO2 nanospheres to nano-TiO2 is 1:(0.5-2).

[0033] Specifically, step S2 involves a three-step process to construct a high-performance composite filler. In S2.1, adjusting the pH to 9-10 with NaOH activates the surface of porous SiO2 nanospheres, generating more hydroxyl sites and enhancing their subsequent binding ability with TiO2. Centrifugation and washing to neutrality prevent residual alkali from interfering with the reaction. In S2.2, 15nm nano-TiO2 is selected, dispersed with ethanol, and ultrasonically treated to ensure uniform distribution of TiO2. The pH is adjusted to 4-5 to promote its adsorption on the SiO2 surface and within the pores. A reaction at 60℃ strengthens the loading, and calcination at 500℃ further stabilizes the bonding. The mass ratio of SiO2 nanospheres to nano-TiO2 is 1:1.25 to balance the loading and dispersibility. In S2.3, ethyl acetate dissolves the EPS copolymer, and ultrasonic dispersion and reflux at 80℃ promote its full grafting onto the SiO2@TiO2 surface. Vacuum drying ensures the purity of the filler.

[0034] As one of the preferred embodiments of the present invention, in step S3: the reaction solvent is tetrahydrofuran, the reaction conditions are stirring at 60-70°C for 4-6 hours under a nitrogen atmosphere, and the solvent is removed by rotary evaporation to obtain a light yellow viscous liquid.

[0035] The principle of preparing the dynamic covalent crosslinking agent in step S3 is based on the Diels-Alder (DA) cycloaddition reaction of furan and maleimide. Tetrahydrofuran, as a polar aprotic solvent, can effectively dissolve furan methacrylate and maleimide propyltriethoxysilane, ensuring sufficient contact between the two in a homogeneous system. A nitrogen atmosphere can isolate oxygen, prevent the double bond from being oxidized, and ensure the specificity of the reaction. 60-70℃ is the suitable temperature for the DA reaction, which can promote the efficient cycloaddition reaction. Stirring for 4-6 hours ensures that the two monomers react completely in a 1:1 molar ratio. After removing the solvent by rotary evaporation, the resulting pale yellow viscous liquid is the dynamic covalent crosslinking agent containing reversible DA bonds. The siloxane groups in its molecular structure can combine with the substrate or resin, while the dynamic covalent bonds give the crosslinking network reversibility, providing the ink with self-healing properties and storage stability at high temperatures.

[0036] As one of the preferred embodiments of the present invention, the specific steps of step S4 are as follows: First, mix half of the amount of deionized water, wetting and dispersing agent, and half of the amount of defoamer, and stir at 500-800 rpm for 5 minutes. Then add pigment and nanocellulose, and disperse at 2000-2500 rpm for 30-45 minutes. Add waterborne acrylic resin, dynamic covalent crosslinking agent, composite filler, and the remaining deionized water and defoamer at 800-1000 rpm, and stir for 30 minutes. After defoaming, stir at 300-500 rpm for 10 minutes and then filter.

[0037] Specifically, first mix 15 parts deionized water, 2 parts wetting and dispersing agent, and 0.5 parts defoamer, and stir at 650 rpm for 5 minutes. Then add 15 parts pigment and 6 parts nanocellulose, and disperse at 2500 rpm for 30 minutes. Add 60 parts waterborne acrylic resin, 7.5 parts dynamic covalent crosslinking agent, 10 parts composite filler, 15 parts deionized water, and 0.5 parts defoamer at 1000 rpm, stir for 30 minutes, and then stir at 500 rpm for 10 minutes to defoam before filtering.

[0038] The technical solution of the present invention will be further described below through embodiments and comparative examples.

[0039] Example 1 Preparation of a water-based printing ink with high adhesion S1. Preparation of EPS terpolymer Glycidyl methacrylate (GMA, 40 g), ethyl phosphate methacrylate (EMPA, 30 g), γ-methacryloyloxypropyltrimethoxysilane (MOSi, 15 g), and styrene (St, 50 g) were mixed (molar ratio approximately 3.3:2.0:1.0:3.8), and azobisisobutyronitrile (AIBN) was added as an initiator at 1.5% of the total monomer mass. The reaction was carried out under nitrogen protection in an isopropanol solution at 75°C with stirring for 10 hours. After the reaction was complete, the solution was added dropwise to n-hexane to precipitate the product. After filtration, the product was washed three times with n-hexane and finally dried under vacuum at 50°C for 24 hours to obtain a white powdery EPS terpolymer.

[0040] S2. Preparation of SiO2@TiO2@EPS composite filler S2.1. Disperse 5g of porous SiO2 nanospheres in 100mL of deionized water, adjust the pH to 9.5 with NaOH solution, and stir for 2 hours to activate. Centrifuge and wash until neutral, then dry at 80℃.

[0041] S2.2. The activated SiO2 nanospheres were dispersed in 200 mL of ethanol, and 6.25 g of nano-TiO2 particles with a particle size of approximately 15 nm (SiO2:TiO2 mass ratio = 1:1.25) were added. The mixture was ultrasonically dispersed for 30 minutes. The pH was adjusted to 4.5 with dilute hydrochloric acid, and the reaction was carried out at 60 °C for 6 hours. The solid was collected by centrifugation, washed three times each with deionized water and ethanol, and finally calcined in a muffle furnace at 500 °C for 2 hours to obtain the SiO2@TiO2 pre-assembled body.

[0042] S2.3. Dissolve 2g of EPS terpolymer in 50mL of ethyl acetate, add 5g of SiO2@TiO2 pre-assembled material, and ultrasonically disperse for 30 minutes to ensure homogeneity. Then reflux at 80℃ for 12 hours. After the reaction, centrifuge, wash three times with ethyl acetate, and vacuum dry at 60℃ for 24 hours to obtain the final product, SiO2@TiO2@EPS composite filler.

[0043] S3. Preparation of dynamic covalent crosslinking agents 15.0 g of furan methacrylate and 24.7 g of maleimide propyltriethoxysilane were mixed in 100 mL of tetrahydrofuran (THF) at a molar ratio of 1:1. The mixture was stirred at 65 °C for 5 hours under a nitrogen atmosphere. After the reaction was completed, the THF solvent was removed by rotary evaporation to obtain a pale yellow viscous liquid dynamic covalent crosslinking agent.

[0044] S4. Preparation of water-based printing inks Add 15 parts deionized water, 2 parts wetting and dispersing agent (polyether-modified siloxane, BYC-844), and 0.5 parts defoamer (organosilicon, BYK-25550) to a dispersion vessel and stir at 650 rpm for 5 minutes. Add 15 parts pigment (pigment red 122) and 6 parts nanocellulose, increase the speed to 2500 rpm, and disperse at high speed for 30 minutes to obtain a uniform color paste. Reduce the speed to 1000 rpm and add 60 parts water-based acrylic resin, 7.5 parts dynamic covalent crosslinking agent, 10 parts SiO2@TiO2@EPS composite filler, and the remaining 15 parts deionized water and 0.5 parts defoamer in sequence. After the addition is complete, maintain the stirring speed at 1000 rpm for 30 minutes to ensure all components are thoroughly mixed. Finally, reduce the speed to 500 rpm and stir for 10 minutes to remove air bubbles. Filter through a 200-mesh sieve to obtain the high-adhesion water-based printing ink.

[0045] Comparative Example 1 The difference from Example 1 is that the EPS surface modification step of the SiO2@TiO2@EPS composite filler is omitted. After obtaining the SiO2@TiO2 pre-assembled body in step S2.2, the EPS copolymer modification in step S2.3 is not performed, and it is directly used as a filler. The remaining components, dosages, and preparation processes remain unchanged.

[0046] Comparative Example 2 The difference from Example 1 is that the dynamic covalent crosslinking agent is replaced with an equal amount of ordinary crosslinking agent. Step S3 is omitted, and 7.5 parts of an aziridine crosslinking agent (such as XL-702) are used instead. The remaining components, amounts, and preparation process remain unchanged.

[0047] Comparative Example 3 The difference from Example 1 is that the SiO2@TiO2@EPS composite filler is replaced with a simple physically mixed filler. Step S2 is omitted, and 5 parts of fumed SiO2 and 5 parts of rutile titanium dioxide (totaling 10 parts) are added directly. The remaining components, amounts, and preparation process remain unchanged.

[0048] Performance testing The tinting strength of the ink was tested according to GB / T 14624.2 2008. The initial drying time of the ink was tested in accordance with GB / T 13217.5 2008; The test reference for adhesion fastness (coated paper) is GB / T 13217.7-2009 "Test Method for Adhesion Fastness of Liquid Ink"; Test Condition 1: The test is conducted at a temperature of 30℃ and a humidity of 65%; Test Condition 2: The test is conducted at a temperature of 50℃ and a humidity of 65%. According to the above performance testing methods, adhesion strength, tinting strength, and adhesion firmness were tested for Example 1 and Comparative Examples 1-3. The specific results are shown in the table below:

[0049] By comparing the performance test results of Example 1 with those of Comparative Examples 1-3, the following conclusions can be drawn: Comparative Example 1 omitted the surface modification step of the SiO2@TiO2@EPS composite filler and directly used the SiO2@TiO2 pre-assembled body as the filler. The test results showed that the adhesion strength at 30℃ and 50℃ decreased to 92.5% and 90.9%, respectively (compared to 98.2% and 97.4% in Example 1), and the tinting strength also decreased from 95% to 92%. This indicates that the surface modification of the EPS terpolymer, through its multifunctional groups such as epoxy groups, phosphate ester groups, silane ester groups, and benzene rings, can significantly improve the compatibility of the composite filler with waterborne acrylic resin and the interfacial bonding strength with the substrate, which is a key factor in ensuring high ink adhesion and tinting strength.

[0050] In Comparative Example 2, after replacing the dynamic covalent crosslinking agent with a common aziridine crosslinking agent, the adhesion strength at 50°C decreased from 97.4% to 92.5% (a more significant decrease), and the tinting strength also slightly decreased. This indicates that the dynamic covalent crosslinking agent, through the reversible DA cycloaddition reaction between furan and maleimide, forms a dynamic crosslinking network that not only improves film density but also endows the ink with self-healing capabilities at high temperatures, allowing it to maintain excellent adhesion performance even at higher temperatures. In contrast, common crosslinking agents lack reversibility and have poor high-temperature stability.

[0051] Comparative Example 3: After replacing the composite filler with a physically mixed fumed SiO2 and titanium dioxide, the initial drying time decreased from 30 mm to 38 mm (significantly worse drying performance), the tinting strength decreased to 88% (decreased hiding power), and the adhesion strength at 30℃ and 50℃ decreased to 85.9% and 83.9% respectively (significant decrease). This demonstrates that the multi-level structure of the SiO2@TiO2@EPS composite filler, characterized by "porous SiO2-loaded TiO2 + EPS surface modification," can synergistically optimize the composite: the porous framework of SiO2 provides a three-dimensional distribution space for TiO2, enhancing light scattering and hiding power; EPS modification improves the compatibility between inorganic fillers and organic resins; and multifunctional groups enhance interfacial bonding. Simple physical mixing cannot achieve the above synergistic effect, leading to a significant decrease in the overall performance of the ink.

[0052] In summary, the superior performance of the high-adhesion water-based printing ink of the present invention is achieved through the EPS modification of the SiO2@TiO2@EPS composite filler, the reversible crosslinking network of the dynamic covalent crosslinking agent, and the synergistic effect of the multi-level structure of the composite filler. The design of each component is crucial to the ink's adhesion, hiding power, stability, and mechanical properties.

[0053] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A water-based printing ink with high adhesion, characterized in that, By weight, it comprises the following components: 50-70 parts of waterborne acrylic resin, 5-15 parts of SiO2@TiO2@EPS composite filler, 10-25 parts of pigment, 5-10 parts of dynamic covalent crosslinking agent, 3-8 parts of nanocellulose, 1-3 parts of wetting and dispersing agent, 0.5-1.5 parts of defoamer, and 20-35 parts of deionized water.

2. The high-adhesion water-based printing ink according to claim 1, characterized in that, The dynamic covalent crosslinking agent is prepared by reacting furan methacrylate with maleimide propyltriethoxysilane in a molar ratio of 1:

1.

3. The high-adhesion water-based printing ink according to claim 1, characterized in that, The SiO2@TiO2@EPS composite filler was prepared by the following method: a) Provide porous SiO2 nanospheres and nano-TiO2 particles with a particle size smaller than the pore size of SiO2 nanospheres; b) Load nano-TiO2 particles onto the surface and pores of porous SiO2 nanospheres to form a SiO2@TiO2 pre-assembly; c) The SiO2@TiO2 pre-assembled body is surface modified using EPS terpolymer to obtain the SiO2@TiO2@EPS composite filler; The EPS terpolymer is a random copolymer of glycidyl methacrylate (GMA), phosphate ester functional monomer (EMPA), silane ester functional monomer (MOSi), and styrene (St).

4. The high-adhesion water-based printing ink according to claim 3, characterized in that, The phosphate ester functional monomer is ethyl phosphate methacrylate; the silane ester functional monomer is γ-methacryloyloxypropyltrimethoxysilane.

5. The high-adhesion water-based printing ink according to claim 1, characterized in that, The wetting and dispersing agent is a polyether-modified siloxane dispersant; the defoamer is a mineral oil or organosilicon defoamer; the nanocellulose has a length of 0.2-2 μm and a diameter of 5-50 nm.

6. A method for preparing a highly adhesive water-based printing ink as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Preparation of EPS terpolymer Glycidyl methacrylate, phosphate functional monomers, silane functional monomers and styrene were mixed in a molar ratio of (2-4):(1-3):(0.5-1.5):(3-5), an initiator was added, and a free radical copolymerization reaction was carried out under nitrogen protection. After the reaction, the product was precipitated, washed and dried to obtain EPS terpolymer. S2. Preparation of SiO2@TiO2@EPS composite filler S2.

1. Activation treatment of porous SiO2 nanospheres; S2.

2. The activated SiO2 nanospheres were mixed with nano-TiO2 particles, and SiO2@TiO2 pre-assembled bodies were obtained by adsorption and calcination. S2.

3. The surface of the SiO2@TiO2 pre-assembled body is modified with the EPS terpolymer obtained in step S1 to obtain the SiO2@TiO2@EPS composite filler; S3. Preparation of dynamic covalent crosslinking agents Furan methacrylate and maleimide propyltriethoxysilane were mixed in a molar ratio of 1:1, and a solvent was added to react the mixture. After the solvent was removed, a dynamic covalent crosslinking agent was obtained. S4. Preparation of water-based printing inks Deionized water, wetting and dispersing agent, and part of the defoamer are mixed and dispersed, and pigment and nanocellulose are added to prepare color paste; then water-based acrylic resin, dynamic covalent crosslinking agent, SiO2@TiO2@EPS composite filler and the remaining deionized water are added, mixed evenly, and the remaining defoamer is added, and filtered to obtain ink.

7. The method for preparing the highly adhesive water-based printing ink according to claim 6, characterized in that, In step S1: the initiator is azobisisobutyronitrile (AIBN), accounting for 1-2% of the total monomer mass; the reaction conditions are: stirring at 70-80°C for 8-12 hours in isopropanol; the precipitation solvent is n-hexane, and after washing, the product is vacuum dried at 50°C for 24 hours.

8. The method for preparing the highly adhesive water-based printing ink according to claim 6, characterized in that, In step S2.1: porous SiO2 nanospheres are dispersed in deionized water, the pH is adjusted to 9-10 with NaOH, stirred for 2 hours to activate, centrifuged and washed until neutral, and then dried; in step S2.2: SiO2 nanospheres are dispersed in ethanol, nano-TiO2 particles with a particle size of 10-20 nm are added, ultrasonically dispersed for 30 min, the pH is adjusted to 4-5, reacted at 60℃ for 6 hours, centrifuged and washed, and then calcined at 500℃ for 2 hours; in step S2.3: EPS terpolymer is dissolved in ethyl acetate, ultrasonically dispersed with SiO2@TiO2 pre-assembled body, refluxed at 80℃ for 12 hours, centrifuged and washed, and then vacuum dried at 60℃ for 24 hours; and the mass ratio of SiO2 nanospheres to nano-TiO2 is 1:(0.5-2).

9. The method for preparing the highly adhesive water-based printing ink according to claim 6, characterized in that, In step S3: the reaction solvent is tetrahydrofuran, and the reaction conditions are stirring at 60-70℃ for 4-6 hours under a nitrogen atmosphere. The solvent is removed by rotary evaporation to obtain a pale yellow viscous liquid.

10. The method for preparing the highly adhesive water-based printing ink according to claim 6, characterized in that, The specific steps of step S4 are as follows: First, mix half of the deionized water, wetting and dispersing agent, and half of the defoamer, and stir at 500-800 rpm for 5 minutes. Then add the pigment and nanocellulose, and disperse at 2000-2500 rpm for 30-45 minutes. Add the waterborne acrylic resin, dynamic covalent crosslinking agent, composite filler, and the remaining deionized water and defoamer at 800-1000 rpm, and stir for 30 minutes. After defoaming, stir at 300-500 rpm for 10 minutes and then filter.

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