Anti-blocking water-based composite ink and preparation method thereof

Abstract

This application belongs to the field of ink technology and discloses an anti-tack water-based composite ink and its preparation method. The preparation method includes the following steps: adding acrylate monomers to a solvent, heating and stirring to react, obtaining an initial emulsion; then adding epoxy monomers and acrylic monomers to the initial emulsion, continuing stirring, and adjusting the pH to alkaline to obtain a polymer emulsion; adding an amine compound to the polymer emulsion, stirring and mixing to obtain an amine emulsion; then adding a cyclic anhydride compound to the amine emulsion, heating and stirring to react, obtaining a composite emulsion; adding long-chain alkyl isocyanate and functional additives to the composite emulsion, heating and stirring to obtain the water-based composite ink. The water-based composite ink prepared by the above method can effectively reduce the residual moisture after the ink film dries during the printing and drying process, forming an ink film with high hardness, high crosslinking density, and anti-tack properties.

Description

Technical Field

[0001] This application relates to the field of ink technology, specifically to an anti-tack water-based composite ink and its preparation method. Background Technology

[0002] Water-based inks are environmentally friendly inks that use water as the main solvent, replacing the large amounts of toxic and harmful organic solvents in traditional solvent-based inks. Their biggest advantage is that they significantly reduce volatile organic compound (VOC) emissions, avoiding pollution to the atmospheric environment. At the same time, they eliminate the risks of flammability and explosion and solvent odors in printing workshops, improving the working environment for operators. In addition, water-based inks use water as a diluent, which is relatively low in cost, and the cleaning equipment does not require organic solvents, further reducing resource consumption and wastewater treatment burden.

[0003] However, due to the high surface tension and latent heat of vaporization of water, water-based inks are difficult to dry completely during high-speed printing. Residual moisture and amines will continue to soften the ink film resin, causing the ink layers to stick together after the printed materials are stacked or rolled up, which is called reverse sticking. In addition, some water-based inks use resins with a low glass transition temperature (Tg). When the temperature rises in summer, transportation or storage environment, the ink layer becomes soft and sticky, and it is easier to stick to the contact surface when under pressure, which further aggravates the reverse sticking defect. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an anti-stickiness water-based composite ink and its preparation method, which aims to solve the problem of ink film stickiness after printing and drying of water-based composite ink.

[0005] To address the aforementioned technical problems, a method for preparing an anti-tack water-based composite ink is proposed, comprising the following steps: S1. Add acrylate monomers to a solvent, heat and stir to react, and obtain an initial emulsion. Then add epoxy monomers and acrylic monomers to the initial emulsion, continue stirring, and adjust the pH to alkaline to obtain a polymer emulsion. The epoxy monomers contain carbon-carbon double bonds and epoxy groups. S2. Add an amine compound to the polymer emulsion, stir and mix to obtain an amine emulsion, then add a cyclic anhydride compound to the amine emulsion, heat and stir to react, and obtain a composite emulsion, wherein the amine compound contains an amine group and the cyclic anhydride compound contains a cyclic anhydride group. S3. Add long-chain alkyl isocyanate and functional additives to the composite emulsion, heat and stir to obtain water-based composite ink, wherein the long-chain alkyl isocyanate is C 12-18 Long-chain alkyl isocyanates.

[0006] In some embodiments, the acrylic monomer in step S1 is acrylic acid and / or methacrylic acid; The acrylate monomers include at least one of methyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, and isooctyl acrylate; Epoxy monomers include at least one of glycidyl methacrylate, glycidyl acrylate, and allyl glycidyl ether; The solvent consists of water and an emulsifier, wherein the emulsifier is a mixture of anionic and nonionic emulsifiers; Anionic emulsifiers include at least one of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, sodium dodecyl diphenyl ether disulfonate, and sodium fatty alcohol polyoxyethylene ether sulfate. Nonionic emulsifiers include at least one of octylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, isotridecyl alcohol polyoxyethylene ether, and secondary alcohol polyoxyethylene ether.

[0007] In some embodiments, step S1 includes: S1.1 Add the anionic emulsifier and nonionic emulsifier to deionized water, stir to dissolve, and obtain a solvent. The mass ratio of anionic emulsifier: nonionic emulsifier: deionized water is (1.2~1.8):(0.4~0.8):(80~100). S1.2 Add the acrylate monomer to the solvent and stir at 800~1000 rpm at room temperature for 30~40 min to obtain a preemulsion, wherein the mass ratio of acrylate monomer to solvent is (30~50):(80~100); S1.3. Take 15-20% of the total mass of the pre-emulsion and add it to the reactor. Heat the reactor to 78-82℃ and add the first initiator. Stir the reactor at 200-300 rpm for 20-30 min to obtain the seed emulsion. Then, add the remaining pre-emulsion and the second initiator dropwise to the seed emulsion. Keep the reactor at 78-82℃ and stir for 60-70 min to obtain the initial emulsion. The mass ratio of pre-emulsion: first initiator: second initiator is (15-20):(0.2-0.3):(0.2-0.3). Both the first and second initiators are 2-5 wt% ammonium persulfate aqueous solutions. S1.4. Add epoxy monomer, acrylic monomer, and third initiator dropwise to the initial emulsion, stir and react at 78~82℃ for 60~70min, cool to 40~45℃, add dimethylethanolamine to adjust the pH to 7.8~8.2 to obtain a polymer emulsion, wherein the mass ratio of epoxy monomer: acrylic monomer: third initiator: initial emulsion is (12~18):(3~8):(0.2~0.3):(80~100), and the third initiator is an aqueous solution of ammonium persulfate with a concentration of 2~5wt%.

[0008] In some embodiments, the amine compound in step S2 includes at least one of diethylenetriamine, triethylenetetramine, ethylenediamine, and tetraethylenepentamine, and the cyclic anhydride compound includes at least one of succinic anhydride, glutaric anhydride, maleic anhydride, and phthalic anhydride.

[0009] In some embodiments, step S2 includes: S2.1 Add an amine compound to the polymerization emulsion and stir at 35~45℃ and 200~300rpm for 40~60min to obtain an amine emulsion, wherein the molar ratio of the amine group of the amine compound to the epoxy group of the epoxy monomer is (0.4~0.6):1; S2.2 Dissolve the cyclic anhydride compound in 2 to 3 times its own weight of anhydrous ethanol, then add it to the amine emulsion and stir at 400 to 500 rpm for 30 to 40 minutes to obtain a dispersion. The molar ratio of the cyclic anhydride group in the cyclic anhydride compound to the carboxyl group in the acrylic acid monomer is (0.9 to 1.1): 1. S2.3. The dispersion is heated to 60-65℃ at a heating rate of 1-2℃ / min, stirred at 400-500rpm for 2-3 hours, then heated to 75-80℃ and kept at that temperature for 30 minutes. After the reaction is complete, the temperature is lowered to 40℃, and the pH is adjusted to 7.5-8.0 using dimethylethanolamine to obtain the composite emulsion.

[0010] In some embodiments, the long-chain alkyl isocyanate in step S3 includes at least one of octadecyl isocyanate, hexadecyl isocyanate, and dodecyl isocyanate, and the functional additives include at least one of defoamer, antioxidant, and wetting agent. Among them, the defoamer is a polyacrylate defoamer and / or a polyether-modified polysiloxane defoamer; The antioxidants are sterically hindered phenolic antioxidants and / or phosphite antioxidants; The wetting agent is an acetylenic diol wetting agent and / or a polyether-modified organosilicon wetting agent.

[0011] In some embodiments, step S3 includes: S3.1 Add long-chain alkyl isocyanate at 40~45℃ to the composite emulsion, add catalyst under stirring at 1000~1200rpm, heat to 55~65℃, and continue stirring for 2~3h to obtain reaction solution, wherein the mass ratio of long-chain alkyl isocyanate:catalyst:composite emulsion is (6~10):(0.1~0.2):100, and the catalyst includes at least one of bismuth neodecanoate, dibutyltin dilaurate, stannous octoate, and organozinc catalyst; S3.2 Add the quenching agent to the reaction solution at 55~65℃, stir the reaction at 500~600rpm for 20~30min to obtain the quenching solution. The quenching agent is a 3~5wt% aqueous solution of ethanolamine, and the amount of quenching agent added is 0.3~0.8wt% of the mass of the reaction solution. S3.3 After the quenching liquid is cooled to 40℃, add the functional additives and stir and disperse at 400~500rpm to obtain water-based composite ink, wherein the mass of the functional additives is 0.5~1.5wt% of the mass of the quenching liquid.

[0012] In addition, an anti-tack water-based composite ink is provided, which is prepared by the above-described method for preparing an anti-tack water-based composite ink.

[0013] The beneficial effects of this invention are as follows: Step S1 introduces epoxy and carboxyl groups into the polymer chain through copolymerization of acrylate monomers with epoxy and acrylic monomers. Although the carboxyl groups are hydrophilic sites, they provide the reaction basis for subsequent crosslinking and consumption. In step S2, aliphatic amines undergo ring-opening addition with epoxy groups to form the first CN crosslinking network, which improves the cohesive strength and hardness of the ink film. At the same time, cyclic anhydrides and carboxyl groups undergo ring-opening to form ester-acid bonds, constructing the second crosslinking network. This process consumes some of the water-absorbing carboxyl groups and generates hydrolysis-resistant ester bonds, which reduces the ink film's affinity for water and also improves the crosslinking effect. The movement of polymer chains is restricted. In step S3, long-chain alkyl isocyanates undergo multi-site cross-linking reactions with residual carboxyl and hydroxyl groups to form a third dense three-dimensional network, further consuming hydrophilic groups. Simultaneously, the covalently grafted long-chain alkyl groups migrate to the surface during film formation, forming a hydrophobic barrier. This migration process carries the internal hydrophobic long chains to the surface, leaving microscopic channels inside the ink film, which facilitates the outward diffusion and evaporation of deep moisture. On the other hand, the formation of the hydrophobic barrier displaces internal moisture, accelerating its escape from the edges of the ink film or areas not fully covered. Through three-step reactions that progressively consume hydrophilic groups, the ink film transforms from a hydrophilic thermoplastic to a hydrophobic thermosetting state. During drying, internal moisture is more easily discharged, preventing moisture residue from forming a plasticizing effect within the film. At the same time, the triple cross-linking network firmly locks the polymer chains, significantly improving the Tg and heat resistance of the ink film. Ultimately, a coating with high hardness, high cross-linking density, and low hydrophilicity is formed, effectively solving the problem of re-sticking caused by moisture residue or high-temperature softening after printing and drying. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a method for preparing an anti-tack water-based composite ink in one embodiment. Detailed Implementation

[0015] In the description of this application, it should be noted that, unless specific conditions are specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0016] Please refer to Figure 1 This invention proposes a method for preparing an anti-tack water-based composite ink, which includes the following preparation steps: S1. Add acrylate monomers to a solvent, heat and stir to react, and obtain an initial emulsion. Then add epoxy monomers and acrylic monomers to the initial emulsion, continue stirring, and adjust the pH to alkaline to obtain a polymer emulsion. The epoxy monomers contain carbon-carbon double bonds and epoxy groups.

[0017] The acrylate monomers include at least one of methyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, and isooctyl acrylate; the epoxy monomers include at least one of glycidyl methacrylate, glycidyl acrylate, and allyl glycidyl ether; and the acrylic monomers are acrylic acid and / or methacrylic acid.

[0018] By copolymerizing acrylate monomers with epoxy monomers and acrylic monomers, epoxy and carboxyl groups are introduced into the polymer chain. Although the carboxyl group is a hydrophilic site, it provides the reaction basis for subsequent crosslinking and consumption.

[0019] The solvent consists of water and an emulsifier, wherein the emulsifier is a mixture of anionic and nonionic emulsifiers; the anionic emulsifier includes at least one of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, sodium dodecyl diphenyl ether disulfonate, and sodium fatty alcohol polyoxyethylene ether sulfate; the nonionic emulsifier includes at least one of octylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, isotridecyl alcohol polyoxyethylene ether, and secondary alcohol polyoxyethylene ether.

[0020] The emulsifier, composed of a mixture of anionic and nonionic emulsifiers, plays a crucial role in providing colloidal stability for emulsion polymerization and subsequent multi-step reactions. Anionic emulsifiers adsorb onto the surfaces of monomer droplets and latex particles, generating electrostatic repulsion through their negatively charged hydrophilic head groups. This prevents latex particles from colliding and agglomerating, ensuring the formation of a stable emulsion with fine particle size and uniform distribution during the S1 polymerization stage. Simultaneously, the micelles they form provide nucleation sites for the polymerization reaction. The polyoxyethylene chains of the nonionic emulsifier extend into the aqueous phase to form a hydration layer, further preventing latex particle aggregation through steric hindrance, an effect that is insensitive to electrolyte and pH fluctuations. Furthermore, during subsequent reactions, the compounded emulsifier system, through the dual stabilizing mechanisms of electrostatic repulsion and steric hindrance, effectively resists pH changes, ionic strength, and organic solvent impacts, preventing demulsification, gelation, or particle size increase, ensuring the smooth implementation of the reaction, and ultimately obtaining a uniform and stable waterborne composite ink.

[0021] Step S1 includes: S1.1 Add the anionic emulsifier and nonionic emulsifier to deionized water and stir to dissolve, obtaining a solvent. The mass ratio of anionic emulsifier:nonionic emulsifier:deionized water is (1.2~1.8):(0.4~0.8):(80~100). This ratio ensures that the emulsifier concentration is higher than the critical micelle concentration, providing sufficient nucleation sites. The anionic emulsifier prevents latex particle aggregation through electrostatic repulsion, while the nonionic emulsifier enhances colloidal stability through steric hindrance. Together, they prepare a uniformly distributed emulsion. The appropriate total amount of emulsifier ensures polymerization stability while avoiding decreased water resistance or foaming problems, laying a good foundation for subsequent pre-emulsification and seed polymerization.

[0022] S1.2 Add the acrylate monomer to the solvent and stir at 800-1000 rpm at room temperature for 30-40 minutes to obtain a pre-emulsion. The mass ratio of acrylate monomer to solvent is (30-50):(80-100). The shear force provided by high-speed stirring breaks the monomer into submicron-sized droplets, which is beneficial for the uniform diffusion of monomer from droplets to latex particles in the subsequent polymerization reaction. The appropriate amount of 30-50 parts of monomer ensures the final solid content of the emulsion while avoiding excessive viscosity or difficulty in heat dissipation during polymerization due to excessive solid content. The pre-emulsification time of 30-40 minutes allows the emulsifier to be fully adsorbed on the surface of the monomer droplets, forming a stable pre-emulsion.

[0023] S1.3. Take 15-20% of the total mass of the pre-emulsion and add it to the reactor. Heat the reactor to 78-82℃ and add the first initiator. Stir the reactor at 200-300 rpm for 20-30 min to obtain the seed emulsion. Then, add the remaining pre-emulsion and the second initiator dropwise to the seed emulsion. Keep the reactor at 78-82℃ and stir for 60-70 min to obtain the initial emulsion. The mass ratio of pre-emulsion: first initiator: second initiator is (15-20):(0.2-0.3):(0.2-0.3). Both the first and second initiators are 2-5 wt% ammonium persulfate aqueous solutions.

[0024] Take 15-20% of the total pre-emulsion as seeds, add the first initiator at 78-82℃ and react for 20-30 minutes to form stable seed latex particles, providing a uniform growth template for subsequent monomer polymerization and ensuring controllable latex particle size and narrow distribution. Secondly, use a semi-continuous dripping method to simultaneously add the remaining pre-emulsion and the second initiator, keeping the polymerization reaction in a starved dripping state, with the monomer dripping rate lower than the polymerization rate, preventing monomer accumulation leading to explosive polymerization or secondary nucleation, thus obtaining an initial emulsion with uniform particle size and regular structure. Furthermore, the mass ratio of pre-emulsion to initiator is controlled at (15-20):(0.2-0.3):(0.2-0.3), with a moderate initiator dosage, maintaining a stable polymerization rate while avoiding excessive initiator leading to excessively low molecular weight or residual ions affecting the ink film's water resistance. Finally, the 2-5 wt% ammonium persulfate aqueous solution concentration is designed to facilitate precise control of the initiator addition, ensuring polymerization reproducibility and laying the foundation for subsequent shell functionalization.

[0025] S1.4. Add epoxy monomer, acrylic monomer, and third initiator dropwise to the initial emulsion, stir and react at 78~82℃ for 60~70min, cool to 40~45℃, add dimethylethanolamine to adjust the pH to 7.8~8.2 to obtain a polymer emulsion, wherein the mass ratio of epoxy monomer: acrylic monomer: third initiator: initial emulsion is (12~18):(3~8):(0.2~0.3):(80~100), and the third initiator is an aqueous solution of ammonium persulfate with a concentration of 2~5wt%.

[0026] The epoxy monomers and acrylic monomers are further copolymerized at 78-82°C. Since the reaction occurs on the surface of the already formed seed latex particles, the newly introduced epoxy groups are mainly distributed in the latex particle shell, providing highly accessible reaction sites for the crosslinking reaction of aliphatic amines in subsequent steps, avoiding the waste caused by epoxy groups being embedded inside the latex particles. Secondly, the carboxyl groups of the acrylic monomers are uniformly introduced at this stage, providing additional colloidal stability to the emulsion and serving as key functional groups for reactions with cyclic anhydrides and long-chain alkyl isocyanates in subsequent steps. Furthermore, the amount of the third initiator is moderate, ensuring the shell polymerization reaction proceeds smoothly without initiating new latex particles. Finally, after cooling to 40-45°C, dimethylethanolamine is used to adjust the pH to 7.8-8.2. This neutralizes some of the carboxyl groups, enhancing emulsion stability, and avoids the use of ammonia (to prevent side reactions between ammonia and epoxy groups), ensuring a high retention rate of epoxy groups during storage and subsequent reactions.

[0027] S2. Add an amine compound to the polymer emulsion and stir to mix to obtain an amine emulsion. Then add a cyclic anhydride compound to the amine emulsion and heat and stir to react to obtain a composite emulsion. The amine compound contains an amine group and the cyclic anhydride compound contains a cyclic anhydride group.

[0028] In step S2, the amine compound includes at least one of diethylenetriamine, triethylenetetramine, ethylenediamine, and tetraethylenepentamine, and the cyclic anhydride compound includes at least one of succinic anhydride, glutaric anhydride, maleic anhydride, and phthalic anhydride.

[0029] In the amine compound, the primary amine group preferentially undergoes a ring-opening addition reaction with the epoxy group introduced in step S1, forming a first-order CN covalent crosslinking network. This network significantly improves the cohesive strength and glass transition temperature of the ink film. Secondly, the cyclic anhydride compound undergoes a ring-opening esterification reaction with the carboxyl group in the system under heating conditions, forming an ester-acid structure and constructing a second-order crosslinking network, further increasing the crosslinking density. This reaction simultaneously consumes the hygroscopic carboxyl group, converting it into a hydrolysis-resistant ester bond, thus reducing the ink film's affinity for water from a chemical structural perspective. The synergistic use of the aliphatic amine and the cyclic anhydride makes the two reactions independent yet complementary: the preferential reaction of the amine group with the epoxy group avoids competitive side reactions with the anhydride, while the reaction of the anhydride with the carboxyl group consumes the hydrophilic group and reserves new free carboxyl groups as reaction sites for step S3.

[0030] Step S2 includes: S2.1 Add an amine compound to the polymer emulsion and stir at 35~45℃ and 200~300rpm for 40~60min to obtain an amine emulsion, wherein the molar ratio of the amine group of the amine compound to the epoxy group of the epoxy monomer is (0.4~0.6):1.

[0031] The molar ratio of amine to epoxy groups is controlled at (0.4~0.6):1. Since the total amount of amine groups is lower than that of epoxy groups, all added amine groups are completely consumed by epoxy groups. After the reaction, there are no free amine groups in the system, avoiding competitive side reactions between amine groups and anhydrides when adding cyclic anhydrides in the subsequent S2.2 step. This ensures that the cyclic anhydrides can selectively react with carboxyl groups to generate the desired ester-acid structure. Secondly, the reaction temperature of 35~45℃ is moderate, ensuring the complete ring-opening reaction of the epoxy-amine while avoiding high-temperature-induced epoxy group hydrolysis. Furthermore, stirring at 200~300 rpm for 40~60 min ensures the uniform dispersion and complete reaction of the aliphatic amine in the emulsion, resulting in a uniform distribution of the first CN crosslinking network on the surface of the latex particles.

[0032] S2.2 Dissolve the cyclic anhydride compound in 2 to 3 times its own weight of anhydrous ethanol, then add it to the amine emulsion and stir at 400 to 500 rpm for 30 to 40 minutes to obtain a dispersion. The molar ratio of the cyclic anhydride group in the cyclic anhydride compound to the carboxyl group in the acrylic acid monomer is (0.9 to 1.1): 1.

[0033] Anhydrous ethanol, used as a co-solvent, ensures that cyclic anhydrides are uniformly dispersed in the aqueous phase at the molecular level, avoiding the problems of uneven dispersion and low contact efficiency that occur when solid particles are added directly. This ensures that the cyclic anhydrides can fully diffuse to the surface of the latex particles and react with the carboxyl groups. Secondly, ethanol is miscible with water, forming a homogeneous system after dropwise addition, preventing emulsion demulsification or excessively high local concentrations. Simultaneously, the addition of ethanol reduces the polarity of the aqueous phase, which is beneficial for the enrichment of cyclic anhydrides at the interface, improving the selectivity and conversion rate of the ring-opening esterification reaction.

[0034] S2.3. The dispersion is heated to 60-65℃ at a heating rate of 1-2℃ / min, stirred at 400-500rpm for 2-3 hours, then heated to 75-80℃ and kept at that temperature for 30 minutes. After the reaction is complete, the temperature is lowered to 40℃, and the pH is adjusted to 7.5-8.0 using dimethylethanolamine to obtain the composite emulsion.

[0035] A slow heating rate of 1-2℃ / min ensures a uniform temperature rise in the system, preventing localized overheating that could lead to hydrolysis of epoxy groups or excessive hydrolysis of acid anhydrides. This also provides activation energy for the ring-opening esterification reaction between cyclic acid anhydrides and carboxyl groups. The reaction is then maintained at 60-65℃ for 2-3 hours. Ethanol acts as a co-solvent, keeping the cyclic acid anhydrides in a molecularly dispersed state. This allows for ring-opening esterification with the carboxyl groups on the latex particle surface under near-homogeneous conditions, resulting in a rapid reaction rate and high conversion rate. This ensures the ring-opening reaction is completed before significant ethanol evaporation, avoiding the precipitation of acid anhydrides as solid particles after ethanol evaporation. After the reaction, the temperature is raised to 75-80℃ and maintained for 30 minutes. The boiling point of ethanol (78.4℃) is used to thoroughly remove residual ethanol, preventing interference from organic solvents in the subsequent S3 step's long-chain alkyl isocyanate grafting reaction and reducing the VOC content of the ink. Finally, after cooling to 40°C, the pH was adjusted to 7.5-8.0 with dimethylethanolamine to neutralize the residual carboxyl groups in the system, improve the stability of the emulsion, and provide a stable alkaline reaction environment for step S3.

[0036] S3. Add long-chain alkyl isocyanate and functional additives to the composite emulsion, heat and stir to obtain water-based composite ink, wherein the long-chain alkyl isocyanate is C 12-18 Long-chain alkyl isocyanates.

[0037] In step S3, the long-chain alkyl isocyanate includes at least one of octadecyl isocyanate, hexadecyl isocyanate, and dodecyl isocyanate, and the functional additives include at least one of defoamer, antioxidant, and wetting agent.

[0038] Long-chain alkyl isocyanates (C12-18) undergo multi-site cross-linking reactions with residual carboxyl and hydroxyl groups in the composite emulsion to form a third dense three-dimensional network, which firmly locks the polymer chains and significantly improves the anti-stickiness of the ink film. At the same time, the covalently grafted long-chain alkyl groups migrate to the surface during film formation to form a hydrophobic barrier. This hydrophobic barrier, on the one hand, repels internal moisture from diffusing to the surface and accelerates evaporation during drying, reducing the residual moisture in the ink film, and on the other hand, prevents external moisture from entering the ink film, avoiding moisture absorption and softening.

[0039] The defoamer is a polyacrylate defoamer and / or a polyether-modified polysiloxane defoamer, specifically including polyacrylate homopolymer emulsion BYK-024, etc., which is used to suppress the generation of bubbles during ink preparation and printing, avoid surface defects such as pinholes and craters in the ink film, and ensure the smoothness and gloss of the coating.

[0040] The antioxidants are sterically hindered phenolic antioxidants and / or phosphite antioxidants, specifically including antioxidant 1010, antioxidant 168, etc., which prevent the long carbon chains grafted with long-chain alkyl isocyanates from undergoing oxidative degradation during high-temperature drying, while inhibiting yellowing of the ink film caused by light and heat, ensuring the integrity of the hydrophobic layer and the storage stability of the ink.

[0041] The wetting agent is an acetylenic diol wetting agent and / or a polyether-modified silicone wetting agent, specifically including acetylenic diol wetting agents TL-104E, TL-604, etc., which are used to reduce the dynamic surface tension of ink, improve the wetting and spreading ability of low surface energy substrates such as plastics and films, and prevent pinholes and craters.

[0042] Step S3 includes: S3.1 Add long-chain alkyl isocyanate at 40~45℃ to the composite emulsion, add catalyst under stirring at 1000~1200rpm, heat to 55~65℃, and continue stirring for 2~3h to obtain reaction solution, wherein the mass ratio of long-chain alkyl isocyanate:catalyst:composite emulsion is (6~10):(0.1~0.2):100, and the catalyst includes at least one of bismuth neodecanoate, dibutyltin dilaurate, stannous octoate, and organozinc catalyst.

[0043] Long-chain alkyl isocyanates are preheated to 40-45°C to significantly reduce their viscosity and achieve good flowability, facilitating rapid dispersion into tiny droplets under high-shear stirring at 1000-1200 rpm, thus increasing the contact area with latex particles in the aqueous phase. The mass ratio of long-chain alkyl isocyanates to the composite emulsion is controlled at (6-10):100. This ratio ensures the formation of a dense hydrophobic layer after grafting while avoiding excessive cross-linking or gelation due to excess isocyanate. A catalyst is added to catalyze the reaction between isocyanate groups and carboxyl and hydroxyl groups, improving grafting efficiency. The temperature is raised to 55-65°C and stirred for 2-3 hours to provide sufficient activation energy for multi-site cross-linking reactions between isocyanate and carboxyl, hydroxyl, and free carboxyl groups in the ester-acid structure generated in step S2, forming a third dense three-dimensional network. Simultaneously, the long-chain alkyl groups are firmly anchored to the polymer side chains through covalent bonds, laying the chemical foundation for surface migration and hydrophobic barrier construction during film formation.

[0044] S3.2 Add quenching agent to the reaction solution at 55~65℃, stir and react at 500~600rpm for 20~30min to obtain quenching solution, wherein the quenching agent is an aqueous solution of ethanolamine with a concentration of 3~5wt%, and the amount of quenching agent added is 0.3~0.8wt% of the mass of the reaction solution.

[0045] The amine groups of ethanolamine react rapidly with residual isocyanate groups to form stable urea bonds, completely eliminating residual -NCO and preventing viscosity increases, gelation, or bubble formation during storage or printing. The amount of quencher added is controlled at 0.3~0.8wt% of the reaction solution mass, with a concentration of 3~5wt%, ensuring the conversion rate of residual -NCO while avoiding excessive residue that could affect ink film performance. Stirring at 500~600rpm for 20~30min ensures uniform dispersion. The hydroxyl groups of ethanolamine act as hydrophilic groups to improve the water dispersion stability of the ink, and the quenching reaction produces no harmful byproducts, ensuring the storage stability and printing safety of the ink.

[0046] S3.3 After the quenching liquid is cooled to 40℃, add the functional additives and stir and disperse at 400~500rpm to obtain water-based composite ink, wherein the mass of the functional additives is 0.5~1.5wt% of the mass of the quenching liquid.

[0047] In addition, an anti-tack water-based composite ink is provided, which is prepared by the above-described method for preparing an anti-tack water-based composite ink.

[0048] For example, the present invention provides the following specific embodiments to illustrate the specific preparation method: Example 1: S1.1 Add sodium dodecylbenzenesulfonate and octylphenol polyoxyethylene ether to deionized water and stir to dissolve to obtain a solvent, wherein the mass ratio of sodium dodecylbenzenesulfonate: octylphenol polyoxyethylene ether: deionized water is 1.5:0.6:90; S1.2 Add methyl methacrylate to the solvent and stir at 900 rpm at room temperature for 35 min to obtain a pre-emulsion, wherein the mass ratio of methyl methacrylate to solvent is 40:90; S1.3. Take 18% of the total mass of the pre-emulsion and add it to the reactor. Heat the reactor to 80°C and add the first initiator. Stir the reactor at 250 rpm for 25 min to obtain the seed emulsion. Then, continue to add the remaining pre-emulsion and the second initiator dropwise to the seed emulsion. Keep the reactor at 80°C and stir for 65 min to obtain the initial emulsion. The mass ratio of pre-emulsion: first initiator: second initiator is 18:0.25:0.25. Both the first initiator and the second initiator are 3 wt% ammonium persulfate aqueous solutions. S1.4. Glycidyl methacrylate, acrylic acid, and the third initiator were added dropwise to the initial emulsion. The mixture was stirred at 80°C for 65 min, cooled to 42°C, and dimethylethanolamine was added to adjust the pH to 7.8-8.2 to obtain a polymer emulsion. The mass ratio of glycidyl methacrylate: acrylic acid: third initiator: initial emulsion was 15:5:0.25:90. The third initiator was a 3 wt% aqueous solution of ammonium persulfate. S2.1 Add diethylenetriamine to the polymer emulsion and stir at 40°C and 250 rpm for 50 min to obtain an amine emulsion, wherein the molar ratio of the amino group of diethylenetriamine to the epoxy group of glycidyl methacrylate is 0.5:1. S2.2 Dissolve succinic anhydride in 2 to 3 times its own weight of anhydrous ethanol, then add it to the amine emulsion and stir at 450 rpm for 35 min to obtain a dispersion, wherein the molar ratio of anhydride groups in succinic anhydride to carboxyl groups in acrylic acid is 1:1. S2.3. The dispersion was heated to 62℃ at a heating rate of 1.5℃ / min, stirred at 450rpm for 2.5h, then heated to 78℃ and kept at that temperature for 30min. After the reaction was completed, the temperature was lowered to 40℃, and the pH was adjusted to 7.5~8.0 using dimethylethanolamine to obtain the composite emulsion. S3.1 Add octadecyl isocyanate at 42℃ to the composite emulsion, add bismuth neodecanoate under stirring at 1100 rpm, heat to 60℃, and continue stirring for 2.5 h to obtain the reaction solution, wherein the mass ratio of octadecyl isocyanate:bismuth neodecanoate:composite emulsion is 8:0.15:100; S3.2 Add quenching agent to the reaction solution at 60℃, stir at 550 rpm for 25 min to obtain quenching solution, wherein the quenching agent is a 4 wt% aqueous solution of ethanolamine, and the amount of quenching agent added is 0.5 wt% of the mass of the reaction solution; S3.3 After the quenching liquid is cooled to 40℃, add the functional additives and stir and disperse at 400~500rpm to obtain water-based composite ink. The mass of the functional additives is 1% of the mass of the quenching liquid, and the functional additives are composed of BYK-024, antioxidant 1010 and TL-104E in a mass ratio of 0.4:0.2:0.4.

[0049] Example 2: The process is basically the same as in Example 1, except that in step S1, the acrylate monomer is butyl methacrylate, the epoxy monomer is glycidyl acrylate, and the acrylic monomer is methacrylic acid.

[0050] Comparative Example 1: It is basically the same as Example 1, except that glycidyl methacrylate was not added in step S1.4, that is, no epoxy monomer was added.

[0051] Comparative Example 2: It is basically the same as Example 1, except that acrylic acid was not added in step S1.4, that is, no acrylic acid monomer was added.

[0052] Comparative Example 3: It is basically the same as Example 1, except that diethylenetriamine was not added in step S2.1, that is, no amine compound was added.

[0053] Comparative Example 4: It is basically the same as Example 1, except that succinic anhydride was not added in step S2.2, that is, no cyclic anhydride compound was added.

[0054] Comparative Example 5: It is basically the same as Example 1, except that acetic anhydride is used instead of succinic anhydride in step S2.2.

[0055] Comparative Example 6: It is basically the same as Example 1, except that octadecyl isocyanate was not used in step S3.1, that is, long-chain alkyl isocyanate was not used.

[0056] Performance testing: Anti-tack test: The test was conducted according to GB / T 13217.8-2009, and the test results are shown in Table 1.

[0057] Table 1 Ink anti-tack test: As shown in Table 1, the adhesion degree of the water-based composite ink film after drying in Examples 1-2 of this application is ≤5%, which can effectively achieve the anti-tack effect. However, compared with Example 1, Comparative Examples 1-4 and Comparative Example 6 lack one of the following raw materials: epoxy monomer, acrylic monomer, amine compound, cyclic anhydride compound, and long-chain alkyl isocyanate. This results in the absence of the cross-linking network in the reaction process, which leads to a decrease in the anti-tack effect of the ink film. Further observation of Examples 1 and Comparative Example 5 shows that when the original cyclic anhydride compound is replaced with a chain anhydride compound, the chain anhydride has an extremely fast hydrolysis rate in the water-based emulsion. It cannot reach the surface of the latex particles in the form of intact anhydride to undergo a ring-opening esterification reaction with the carboxyl groups to generate an ester-acid structure and construct a second cross-linking network, which in turn leads to a decrease in the anti-tack effect of the ink film.

[0058] The above embodiments are preferred embodiments of this application, but the implementation of this application is not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of this application shall be considered equivalent substitutions and shall be included within the protection scope of this application.

Claims

1. A method for preparing an anti-blocking water-based composite ink, characterized by, The preparation method includes the following steps: S1. Add acrylate monomers to a solvent, heat and stir to react, and obtain an initial emulsion. Then add epoxy monomers and acrylic monomers to the initial emulsion, continue stirring, and adjust the pH to alkaline to obtain a polymer emulsion. The epoxy monomers contain carbon-carbon double bonds and epoxy groups. S2. Add an amine compound to the polymer emulsion, stir and mix to obtain an amine emulsion, then add a cyclic anhydride compound to the amine emulsion, heat and stir to react, and obtain a composite emulsion, wherein the amine compound contains an amine group and the cyclic anhydride compound contains a cyclic anhydride group. S3. Add long-chain alkyl isocyanate and functional additives to the composite emulsion, heat and stir to obtain water-based composite ink, wherein the long-chain alkyl isocyanate is C 12-18 Long-chain alkyl isocyanates.

2. The method of claim 1, wherein the water-based composite ink is prepared by adding the water-based pigment ink, the water-based binder, and the water-based surfactant to the water-based carrier, and then stirring the mixture. In step S1, the acrylic monomer is acrylic acid and / or methacrylic acid; The acrylate monomers include at least one of methyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, and isooctyl acrylate; Epoxy monomers include at least one of glycidyl methacrylate, glycidyl acrylate, and allyl glycidyl ether; The solvent consists of water and an emulsifier, wherein the emulsifier is a mixture of anionic and nonionic emulsifiers; Anionic emulsifiers include at least one of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, sodium dodecyl diphenyl ether disulfonate, and sodium fatty alcohol polyoxyethylene ether sulfate. Nonionic emulsifiers include at least one of octylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, isotridecyl alcohol polyoxyethylene ether, and secondary alcohol polyoxyethylene ether.

3. The method of claim 2, wherein the water-based composite ink is prepared by adding the water-based pigment ink, the water-based binder, and the water-based surfactant to the water-based carrier, and then stirring the mixture. Step S1 includes: S1.1 Add the anionic emulsifier and nonionic emulsifier to deionized water, stir to dissolve, and obtain a solvent. The mass ratio of anionic emulsifier: nonionic emulsifier: deionized water is (1.2~1.8):(0.4~0.8):(80~100). S1.2 Add the acrylate monomer to the solvent and stir at 800~1000 rpm at room temperature for 30~40 min to obtain a preemulsion, wherein the mass ratio of acrylate monomer to solvent is (30~50):(80~100); S1.

3. Take 15-20% of the total mass of the pre-emulsion and add it to the reactor. Heat the reactor to 78-82℃ and add the first initiator. Stir the reactor at 200-300 rpm for 20-30 min to obtain the seed emulsion. Then, add the remaining pre-emulsion and the second initiator dropwise to the seed emulsion. Keep the reactor at 78-82℃ and stir for 60-70 min to obtain the initial emulsion. The mass ratio of pre-emulsion: first initiator: second initiator is (15-20):(0.2-0.3):(0.2-0.3). Both the first and second initiators are 2-5 wt% ammonium persulfate aqueous solutions. S1.

4. Add epoxy monomer, acrylic monomer, and third initiator dropwise to the initial emulsion, stir and react at 78~82℃ for 60~70min, cool to 40~45℃, add dimethylethanolamine to adjust the pH to 7.8~8.2 to obtain a polymer emulsion, wherein the mass ratio of epoxy monomer: acrylic monomer: third initiator: initial emulsion is (12~18):(3~8):(0.2~0.3):(80~100), and the third initiator is an aqueous solution of ammonium persulfate with a concentration of 2~5wt%.

4. The method of claim 1, wherein the water-based composite ink is prepared by adding the water-based pigment ink, the water-based binder, and the water-based surfactant to the water-based carrier, and then stirring the mixture. In step S2, the amine compound includes at least one of diethylenetriamine, triethylenetetramine, ethylenediamine, and tetraethylenepentamine, and the cyclic anhydride compound includes at least one of succinic anhydride, glutaric anhydride, maleic anhydride, and phthalic anhydride.

5. The method of claim 1 or 4, wherein the water-based composite ink is prepared by adding the water-soluble or water-dispersible polymer to the water-based composite ink. Step S2 includes: S2.1 Add an amine compound to the polymerization emulsion and stir at 35~45℃ and 200~300rpm for 40~60min to obtain an amine emulsion, wherein the molar ratio of the amine group of the amine compound to the epoxy group of the epoxy monomer is (0.4~0.6):1; S2.2 Dissolve the cyclic anhydride compound in 2 to 3 times its own weight of anhydrous ethanol, then add it to the amine emulsion and stir at 400 to 500 rpm for 30 to 40 minutes to obtain a dispersion. The molar ratio of the cyclic anhydride group in the cyclic anhydride compound to the carboxyl group in the acrylic acid monomer is (0.9 to 1.1):

1. S2.

3. The dispersion is heated to 60-65℃ at a heating rate of 1-2℃ / min, stirred at 400-500rpm for 2-3 hours, then heated to 75-80℃ and kept at that temperature for 30 minutes. After the reaction is complete, the temperature is lowered to 40℃, and the pH is adjusted to 7.5-8.0 using dimethylethanolamine to obtain the composite emulsion.

6. The method for preparing an anti-tack water-based composite ink according to claim 1, characterized in that, In step S3, the long-chain alkyl isocyanate includes at least one of octadecyl isocyanate, hexadecyl isocyanate, and dodecyl isocyanate, and the functional additives include at least one of defoamer, antioxidant, and wetting agent. Among them, the defoamer is a polyacrylate defoamer and / or a polyether-modified polysiloxane defoamer; The antioxidants are sterically hindered phenolic antioxidants and / or phosphite antioxidants; The wetting agent is an acetylenic diol wetting agent and / or a polyether-modified organosilicon wetting agent.

7. A method for preparing an anti-tack water-based composite ink according to claim 1 or 6, characterized in that, Step S3 includes: S3.1 Add long-chain alkyl isocyanate at 40~45℃ to the composite emulsion, add catalyst under stirring at 1000~1200rpm, heat to 55~65℃, and continue stirring for 2~3h to obtain reaction solution, wherein the mass ratio of long-chain alkyl isocyanate:catalyst:composite emulsion is (6~10):(0.1~0.2):100, and the catalyst includes at least one of bismuth neodecanoate, dibutyltin dilaurate, stannous octoate, and organozinc catalyst; S3.2 Add the quenching agent to the reaction solution at 55~65℃, stir the reaction at 500~600rpm for 20~30min to obtain the quenching solution. The quenching agent is a 3~5wt% aqueous solution of ethanolamine, and the amount of quenching agent added is 0.3~0.8wt% of the mass of the reaction solution. S3.3 After the quenching liquid is cooled to 40℃, add the functional additives and stir and disperse at 400~500rpm to obtain water-based composite ink, wherein the mass of the functional additives is 0.5~1.5wt% of the mass of the quenching liquid.

8. A water-based composite ink with anti-tack properties, characterized in that, The anti-tack water-based composite ink is prepared by any one of the preparation methods of the anti-tack water-based composite ink according to claims 1-7.

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