Aqueous ink and method for its preparation

Abstract

The application relates to a kind of water-based ink and its preparation method, and belongs to the technical field of printing ink;The application improves the leveling and adhesion of finished product water-based ink by adding acetoacetoxy ethyl methacrylate and styrene when preparing polyacrylate, improves the wear resistance and hydrophobicity of finished product ink, in addition, the application also prepares a curing agent, which can crosslink with carbonyl in acetoacetoxy ethyl methacrylate under normal temperature conditions, accelerate the curing speed of water-based ink under low temperature conditions, and improve the chemical resistance and weather resistance of water-based ink, the surface drying time of the water-based ink of the application under low temperature (10 DEG C) conditions can also be less than 25s, which can meet the printing speed requirements of modern enterprises.

Description

Technical Field

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

[0002] Water-based ink is a printing material that uses water as its main solvent. Its core components include water-based resin, pigments, additives (such as defoamers and dispersants), and water. Compared with traditional solvent-based inks, water-based inks have a much lower content of volatile organic compounds (VOCs), significantly reducing harm to the human body and offering advantages such as safety, non-toxicity, and environmental friendliness. However, water has a higher boiling point than most commonly used solvents, and the curing of water-based inks relies heavily on water evaporation. This results in a slower surface drying speed for water-based inks compared to traditional solvent-based inks, especially in low winter temperatures, where the drying efficiency of water-based inks will be significantly reduced. Insufficient surface drying of water-based inks can lead to color stacking and blurry printing results, requiring companies to reduce printing speed and add heat drying or infrared drying equipment. Based on this, the present invention provides a water-based ink and its preparation method. Summary of the Invention

[0003] The purpose of this invention is to provide a water-based ink and its preparation method to solve the problems mentioned in the background art.

[0004] The objective of this invention can be achieved through the following technical solutions: A water-based ink comprises the following raw materials: 1-3 parts emulsifier, 2-4 parts ethyl acetoacetate methacrylate, 12-18 parts methyl methacrylate, 5-10 parts styrene, 20-25 parts butyl acrylate, 0.3-0.6 parts acrylic acid, 0.1-0.5 parts sodium bicarbonate, 0.1-0.3 parts initiator, 40-60 parts deionized water, 0.2-0.4 parts defoamer, 0.3-0.5 parts leveling agent, 8-20 parts pigment, and 1-4 parts curing agent; A method for preparing a water-based ink includes the following steps: Step 1: Weigh each raw material according to the specified mass fractions; The second step is to prepare an initiator solution by mixing the initiator with a portion of deionized water for later use. The third step involves adding the emulsifier, ethyl acetoacetate methacrylate, methyl methacrylate, styrene, butyl acrylate, acrylic acid, sodium bicarbonate, and all remaining deionized water to an emulsification tank and stirring to disperse and mix them to obtain an emulsion. Step 4: Add the initiator solution dropwise to the emulsion. After the addition is complete, heat the mixture to 75-90°C and react for 80-120 minutes to obtain a polyacrylate emulsion. Then, cool the polyacrylate emulsion to 30-50°C and add the defoamer, leveling agent, pigment, and curing agent. Stir well to obtain the water-based ink.

[0005] Furthermore, the emulsifier is one or a mixture of two of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate.

[0006] Furthermore, the initiator is ammonium persulfate.

[0007] Furthermore, the defoamer is one or a mixture of BYK-024, BYK-028, and DC-57.

[0008] Furthermore, the leveling agent is one or a mixture of EFKA-3777 and TEGO Rad 2700.

[0009] Furthermore, by mass fraction, the ratio of initiator to deionized water used in the second step is 0.1–0.3:4–10.

[0010] Furthermore, the stirring and dispersion conditions in the third step are to stir for 20 to 40 minutes at a speed of 300 to 400 rpm.

[0011] Furthermore, the conditions for achieving uniform mixing in step four are to stir at a speed of 100–200 rpm for 60–100 min.

[0012] Furthermore, the curing agent is prepared by the following steps: The ultraviolet absorber and anhydrous ethanol were mixed in a three-necked flask, a condenser and a thermometer were attached, a magnetic stirrer was turned on, and the mixture was heated to 80-130°C. Then, hydrazine hydrate solution was added to the three-necked flask, and the mixture was reacted at 80-130°C for 8-12 hours. After the reaction was completed, the mixture was cooled in an ice-water bath, then vacuum filtered. The resulting solid was washed with deionized water and dried to obtain the curing agent.

[0013] Furthermore, the hydrazine hydrate solution is an aqueous solution of hydrazine hydrate with a mass fraction of 80%.

[0014] Furthermore, the ratio of ultraviolet absorber, anhydrous ethanol, and hydrazine hydrate used is 5.6–6 g: 40–60 mL: 4–8 g.

[0015] Furthermore, the ultraviolet absorber has the following structure And it can be made through the following steps: Step 1: Under ice-water bath conditions, 2-nitroaniline, concentrated hydrochloric acid, and deionized water are mixed in a three-necked flask. Magnetic stirring is turned on, and then sodium nitrite solution is added dropwise to the three-necked flask. After the addition is complete, the reaction is carried out under ice-water bath conditions for 30-60 minutes. After the reaction is completed, urea is added to the reaction solution to prevent the starch-potassium iodide test paper from turning blue. The solution is then filtered to obtain a diazonium salt solution, which is refrigerated at 0°C for later use. Step 2: Under ice-water bath conditions, 4-hydroxyisophthalic acid and ethanol solution are mixed in a three-necked flask, magnetic stirring is turned on, and diazonium salt solution is added dropwise to the three-necked flask. After the addition is completed, the ice-water bath is removed and the reaction is carried out at room temperature for 2-6 hours. After the reaction is completed, the mixture is filtered under vacuum. The obtained solid is washed with deionized water and dried to obtain the ultraviolet absorber precursor. Step 3: Mix the UV absorber precursor, ethanol solution, and sodium hydroxide solution in a three-necked flask, turn on magnetic stirring, heat to reflux, add sodium dithionite to the three-necked flask, and continue the reaction under reflux for 1-2 hours. After the reaction is completed, pour the reaction solution into ice water to cool, and acidify with hydrochloric acid to pH 3-5. Then, filter under vacuum, wash the obtained solid with deionized water and dry to obtain the UV absorber.

[0016] Furthermore, the concentrated hydrochloric acid used in step 1 has a mass fraction of 30-38%.

[0017] Furthermore, the sodium nitrite solution used in step 1 is prepared by mixing 5.5–6.9 g of sodium nitrite with 30–40 mL of deionized water.

[0018] Furthermore, the ratio of 2-nitroaniline, concentrated hydrochloric acid, and sodium nitrite solution used in step 1 is 6.9–8.3 g: 30–50 mL: 30–40 mL.

[0019] Furthermore, the ethanol solution used in steps 2 and 3 is an aqueous ethanol solution with a volume fraction of 40-95%.

[0020] Furthermore, the ratio of 4-hydroxyisophthalic acid, ethanol solution, and diazonium salt solution used in step 2 is 6.9–7.7 g: 40–80 mL: 100–110 mL.

[0021] Furthermore, the sodium hydroxide solution used in step 3 is an aqueous sodium hydroxide solution with a mass fraction of 15-25%.

[0022] Furthermore, the ratio of the amount of ultraviolet absorber precursor, ethanol solution, sodium hydroxide solution, and sodium dithionite used in step 3 is 9.2–10.4 g: 60–100 mL: 50–100 mL: 14–20 g.

[0023] The beneficial effects of this invention are: 1) In the preparation of polyacrylate emulsion, the present invention adds ethyl acetoacetate methacrylate and styrene. The flexible segments of ethyl acetoacetate methacrylate can improve the leveling and adhesion of the finished water-based ink, and prevent the penetration of organic solvents after crosslinking with the curing agent, thereby improving the chemical resistance of the finished ink. The rigid benzene ring structure of styrene can increase the steric hindrance between polyacrylate emulsion molecules, improve the abrasion resistance and hydrophobicity of the polyacrylate emulsion, and accelerate the drying speed of the finished water-based ink.

[0024] 2) This invention uses 2-nitroaniline and sodium nitrite as raw materials. Utilizing the strong oxidizing properties of sodium nitrite in a strong acid medium, it undergoes a diazotization reaction with 2-nitroaniline to obtain a diazonium salt solution. This solution then undergoes a coupling reaction at the ortho-hydroxyl position of dimethyl 4-hydroxyisophthalate to obtain a UV absorber precursor. The UV absorber is then reduced and cyclized with sodium dithionite to obtain the UV absorber. Finally, hydrazine hydrate is used to react with the UV absorber in a nucleophilic substitution reaction to obtain a curing agent. The curing agent of this invention has a double-terminated hydrazide structure, enabling it to react and crosslink with the carbonyl group of ethyl acetoacetate at room temperature, accelerating the curing speed of water-based inks under low-temperature conditions and broadening the application scenarios of water-based inks. Furthermore, the curing agent also contains a benzotriazole UV absorber structure, which can chemically crosslink the UV absorber to the polyacrylate molecular chain. After curing and crosslinking, the effective components are not easily migrated, enabling the finished water-based ink to have long-lasting weather resistance.

[0025] 3) The water-based ink of the present invention has good weather resistance, leveling and adhesion, and can adapt to low temperature and high humidity environment. The cured water-based ink has long-lasting weather resistance and is not easily affected by chemical solvents and ultraviolet rays. It can be widely used in the printing and packaging field. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1 A water-based ink comprises the following raw materials: 1 part emulsifier, 2 parts ethyl acetoacetate methacrylate, 12 parts methyl methacrylate, 5 parts styrene, 20 parts butyl acrylate, 0.3 parts acrylic acid, 0.1 parts sodium bicarbonate, 0.1 parts initiator, 40 parts deionized water, 0.2 parts defoamer, 0.3 parts leveling agent, 8 parts pigment, and 1 part curing agent.

[0028] The curing agent is prepared by the following steps: Step 1: Under ice-water bath conditions, 6.9g of 2-nitroaniline, 30mL of 38% hydrochloric acid, and 40mL of deionized water were mixed in a three-necked flask. Magnetic stirring was turned on, and then a solution prepared by 5.5g of sodium nitrite and 40mL of deionized water was added dropwise to the three-necked flask. After the addition was complete, the reaction was carried out under ice-water bath conditions for 30min. After the reaction was completed, urea was added to the reaction solution to prevent the starch-potassium iodide test paper from turning blue. The solution was then filtered to obtain a diazonium salt solution, which was refrigerated at 0℃ for later use. Step 2: Under ice-water bath conditions, 6.9 g of 4-hydroxyisophthalic acid and 40 mL of 95% ethanol aqueous solution were mixed in a three-necked flask. Magnetic stirring was turned on, and 100 mL of diazonium salt solution was added dropwise to the three-necked flask. After the addition was completed, the ice-water bath was removed, and the reaction was carried out at room temperature for 2 h. After the reaction was completed, the mixture was filtered under vacuum. The obtained solid was washed with deionized water and dried to obtain the ultraviolet absorber precursor. Step 3: Mix 9.2g of UV absorber precursor, 60mL of 95% ethanol aqueous solution, and 50mL of 25% sodium hydroxide aqueous solution in a three-necked flask. Turn on magnetic stirring and heat to reflux. Then add 14g of sodium dithionite to the three-necked flask and continue the reaction under reflux for 1h. After the reaction is completed, pour the reaction solution into ice water to cool and acidify it to pH 3 with hydrochloric acid. Then filter under vacuum. Wash the obtained solid with deionized water and dry to obtain the UV absorber. Step 4: Mix 5.6g of UV absorber and 40mL of anhydrous ethanol in a three-necked flask, attach a condenser and thermometer, turn on magnetic stirring, heat to 80℃, then add 4g of 80% hydrazine hydrate solution to the three-necked flask, and react at 80℃ for 8h. After the reaction is complete, cool in an ice-water bath, then filter under vacuum. Wash the obtained solid with deionized water and dry to obtain the curing agent.

[0029] The preparation method of this water-based ink includes the following steps: Step 1: Weigh each raw material according to the specified mass fractions; The second step is to prepare an initiator solution by mixing the initiator with 4 parts of deionized water for later use. Step 3: Add the emulsifier, ethyl acetoacetate methacrylate, methyl methacrylate, styrene, butyl acrylate, acrylic acid, sodium bicarbonate and all remaining deionized water to the emulsification tank and stir for 40 minutes at 300 rpm to obtain the emulsion. Step 4: Add the initiator solution dropwise to the emulsion. After the addition is complete, heat the mixture to 75°C and react for 120 minutes to obtain a polyacrylate emulsion. Then, cool the polyacrylate emulsion to 30°C and add defoamer, leveling agent, pigment, and curing agent. Stir the mixture at 100 rpm for 100 minutes to obtain the water-based ink.

[0030] In this embodiment, the emulsifier used is sodium dodecyl sulfate, the initiator used is ammonium persulfate, the defoamer used is BYK-024, and the leveling agent used is EFKA-3777.

[0031] Example 2 A water-based ink comprises the following raw materials: 2 parts emulsifier, 3 parts ethyl acetoacetate methacrylate, 15 parts methyl methacrylate, 7.5 parts styrene, 22.5 parts butyl acrylate, 0.45 parts acrylic acid, 0.3 parts sodium bicarbonate, 0.2 parts initiator, 50 parts deionized water, 0.3 parts defoamer, 0.4 parts leveling agent, 14 parts pigment, and 2.5 parts curing agent.

[0032] The curing agent is prepared by the following steps: Step 1: Under ice-water bath conditions, 7.6g of 2-nitroaniline, 40mL of 35% hydrochloric acid, and 35mL of deionized water were mixed in a three-necked flask. Magnetic stirring was turned on, and then a solution prepared by 6.2g of sodium nitrite and 40mL of deionized water was added dropwise to the three-necked flask. After the addition was complete, the reaction was carried out under ice-water bath conditions for 45min. After the reaction was completed, urea was added to the reaction solution to prevent the starch-potassium iodide test paper from turning blue. The solution was then filtered to obtain a diazonium salt solution, which was refrigerated at 0℃ for later use. Step 2: Under ice-water bath conditions, 7.3 g of 4-hydroxyisophthalic acid and 60 mL of 70% ethanol aqueous solution were mixed in a three-necked flask. Magnetic stirring was turned on, and 105 mL of diazonium salt solution was added dropwise to the three-necked flask. After the addition was completed, the ice-water bath was removed, and the reaction was carried out at room temperature for 4 h. After the reaction was completed, the mixture was filtered under vacuum. The obtained solid was washed with deionized water and dried to obtain the ultraviolet absorber precursor. Step 3: Mix 9.8g of UV absorber precursor, 80mL of 70% ethanol aqueous solution, and 75mL of 20% sodium hydroxide aqueous solution in a three-necked flask. Turn on magnetic stirring and heat to reflux. Add 17g of sodium dithionite to the three-necked flask and continue the reaction under reflux for 1.5h. After the reaction is completed, pour the reaction solution into ice water to cool and acidify it to pH 4 with hydrochloric acid. Then filter under vacuum. Wash the obtained solid with deionized water and dry to obtain the UV absorber. Step 4: Mix 5.8g of UV absorber and anhydrous ethanol in a three-necked flask, attach a condenser and thermometer, turn on magnetic stirring, heat to 80°C, add 6g of 80% hydrazine hydrate solution to the three-necked flask, and react at 80°C for 10 hours. After the reaction is complete, cool in an ice-water bath, then filter under vacuum. Wash the obtained solid with deionized water and dry to obtain the curing agent.

[0033] The preparation method of this water-based ink includes the following steps: Step 1: Weigh each raw material according to the specified mass fractions; The second step is to prepare an initiator solution by mixing the initiator with 7 parts of deionized water for later use. Step 3: Add the emulsifier, ethyl acetoacetate methacrylate, methyl methacrylate, styrene, butyl acrylate, acrylic acid, sodium bicarbonate and all remaining deionized water to the emulsification tank and stir for 30 minutes at 350 rpm to obtain the emulsion. Step 4: Add the initiator solution dropwise to the emulsion. After the addition is complete, heat the mixture to 83°C and react for 100 minutes to obtain a polyacrylate emulsion. Then, cool the polyacrylate emulsion to 40°C and add defoamer, leveling agent, pigment, and curing agent. Stir the mixture at 150 rpm for 80 minutes to obtain the water-based ink.

[0034] In this embodiment, the emulsifier used is sodium dodecyl sulfate, the initiator used is ammonium persulfate, the defoamer used is BYK-028, and the leveling agent used is EFKA-3777.

[0035] Example 3 A water-based ink comprises the following raw materials: 3 parts emulsifier, 4 parts ethyl acetoacetate methacrylate, 18 parts methyl methacrylate, 10 parts styrene, 25 parts butyl acrylate, 0.6 parts acrylic acid, 0.5 parts sodium bicarbonate, 0.3 parts initiator, 60 parts deionized water, 0.4 parts defoamer, 0.5 parts leveling agent, 20 parts pigment, and 4 parts curing agent.

[0036] The curing agent is prepared by the following steps: Step 1: Under ice-water bath conditions, mix 8.3g of 2-nitroaniline, 50mL of 30% hydrochloric acid, and 30mL of deionized water in a three-necked flask, turn on the magnetic stirrer, and then add dropwise a solution prepared by 6.9g of sodium nitrite and 40mL of deionized water to the three-necked flask. After the addition is complete, react under ice-water bath conditions for 60min. After the reaction is complete, add urea to the reaction solution so that the reaction solution can no longer turn starch potassium iodide test paper blue. Then filter to obtain a diazonium salt solution, and refrigerate at 0℃ for later use. Step 2: Under ice-water bath conditions, 6.9–7.7 g of 4-hydroxyisophthalic acid and 40–80 mL of 40–95% (v / v) ethanol aqueous solution were mixed in a three-necked flask. Magnetic stirring was turned on, and 110 mL of diazonium salt solution was added dropwise to the three-necked flask. After the addition was completed, the ice-water bath was removed, and the reaction was carried out at room temperature for 6 h. After the reaction was completed, the mixture was filtered under vacuum. The obtained solid was washed with deionized water and dried to obtain the ultraviolet absorber precursor. Step 3: Mix 10.4g of UV absorber precursor, 100mL of 40% ethanol aqueous solution, and 50mL of 25% sodium hydroxide aqueous solution in a three-necked flask. Turn on magnetic stirring and heat to reflux. Add 20g of sodium dithionite to the three-necked flask and continue the reaction under reflux for 2 hours. After the reaction is completed, pour the reaction solution into ice water to cool and acidify it to pH 5 with hydrochloric acid. Then, filter under vacuum. Wash the obtained solid with deionized water and dry to obtain the UV absorber. Step 4: Mix 6g of ultraviolet absorber and anhydrous ethanol in a three-necked flask, attach a condenser and thermometer, turn on magnetic stirring, heat to 80°C, then add 8g of 80% hydrazine hydrate solution to the three-necked flask, and react at 80°C for 12 hours. After the reaction is complete, cool in an ice-water bath, then filter under vacuum. Wash the obtained solid with deionized water and dry to obtain the curing agent.

[0037] The preparation method of this water-based ink includes the following steps: Step 1: Weigh each raw material according to the specified mass fractions; The second step is to prepare an initiator solution by mixing the initiator with 10 parts of deionized water for later use. Step 3: Add the emulsifier, ethyl acetoacetate methacrylate, methyl methacrylate, styrene, butyl acrylate, acrylic acid, sodium bicarbonate and all remaining deionized water to the emulsification tank and stir for 20 minutes at 400 rpm to obtain the emulsion. Step 4: Add the initiator solution dropwise to the emulsion. After the addition is complete, heat the mixture to 90°C and react for 80 minutes to obtain a polyacrylate emulsion. Then, cool the polyacrylate emulsion to 50°C and add defoamer, leveling agent, pigment, and curing agent. Stir the mixture at 200 rpm for 60 minutes to obtain the water-based ink.

[0038] In this embodiment, the emulsifier used is sodium dodecylbenzenesulfonate, the initiator used is ammonium persulfate, the defoamer used is DC-57, and the leveling agent used is TEGO Rad 2700.

[0039] Comparative Example 1 The difference between this comparative example and Example 2 is that the curing agent prepared according to the present invention is not used; instead, a conventional ultraviolet absorber is used.

[0040] A water-based ink comprises the following raw materials: 2 parts emulsifier, 3 parts ethyl acetoacetate methacrylate, 15 parts methyl methacrylate, 7.5 parts styrene, 22.5 parts butyl acrylate, 0.45 parts acrylic acid, 0.3 parts sodium bicarbonate, 0.2 parts initiator, 50 parts deionized water, 0.3 parts defoamer, 0.4 parts leveling agent, 14 parts pigment, and 2.5 parts ultraviolet absorber.

[0041] The preparation method of this water-based ink includes the following steps: Step 1: Weigh each raw material according to the specified mass fractions; The second step is to prepare an initiator solution by mixing the initiator with 7 parts of deionized water for later use. Step 3: Add the emulsifier, ethyl acetoacetate methacrylate, methyl methacrylate, styrene, butyl acrylate, acrylic acid, sodium bicarbonate and all remaining deionized water to the emulsification tank and stir for 30 minutes at 350 rpm to obtain the emulsion. Step 4: Add the initiator solution dropwise to the emulsion. After the addition is complete, heat the mixture to 83°C and react for 100 minutes to obtain a polyacrylate emulsion. Then, cool the polyacrylate emulsion to 40°C and add defoamer, leveling agent, pigment, and ultraviolet absorber. Stir the mixture at 150 rpm for 80 minutes to obtain the water-based ink.

[0042] In this comparative example, the emulsifier used was sodium dodecyl sulfate, the initiator used was ammonium persulfate, the defoamer used was BYK-028, the leveling agent used was EFKA-3777, and the ultraviolet absorber used was Tinuvin P.

[0043] Comparative Example 2 This comparative example uses commercially available water-based inks.

[0044] Experimental Example 1 The water-based inks from Examples 1-3 and Comparative Example 1, along with the commercially available water-based ink from Comparative Example 2, were subjected to performance tests. The surface drying time of each component of the water-based ink was tested at 10°C according to GB / T9278-2008, and the lightfastness was tested according to GB / T15102-2017. The test results are shown in Table 1. Table 1

[0045] As can be seen from Table 1, the curing agent of the present invention can effectively improve the UV resistance of water-based inks and increase the surface drying time at low temperatures. The surface drying time of the water-based inks of the present invention is all below 25 seconds, which can meet the printing speed requirements of modern enterprises.

[0046] The present invention provides a detailed description of a water-based ink and its preparation method. Specific examples have been used to illustrate the principles and implementation methods of the invention. The descriptions of these embodiments are merely for the purpose of helping to understand the method and core ideas of the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including manufacturing and using any device or system, and implementing any combination method. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from its principles. In particular, as long as there is no structural conflict, the features in the embodiments disclosed in this invention can be combined with each other in any way. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A water-based ink, characterized in that, The raw materials include the following parts by weight: emulsifier 1-3 parts, ethyl acetoacetate methacrylate 2-4 parts, methyl methacrylate 12-18 parts, styrene 5-10 parts, butyl acrylate 20-25 parts, acrylic acid 0.3-0.6 parts, sodium bicarbonate 0.1-0.5 parts, initiator 0.1-0.3 parts, deionized water 40-60 parts, defoamer 0.2-0.4 parts, leveling agent 0.3-0.5 parts, pigment 8-20 parts, and curing agent 1-4 parts; The curing agent has a double-terminated hydrazide structure, which can react and crosslink with the carbonyl group of ethyl acetoacetate at room temperature, thereby accelerating the curing speed of water-based inks under low-temperature conditions. The curing agent is prepared by the following steps: The ultraviolet absorber was dissolved in anhydrous ethanol and heated to 80°C. Then, hydrazine hydrate solution was added to the system, and the reaction was continued at 80°C to obtain the curing agent. The ultraviolet absorber has the following structure: ; The ultraviolet absorber is prepared by the following steps: 2-Nitroaniline and sodium nitrite solution were mixed and reacted in a strong acid medium under ice-water bath conditions to obtain a diazonium salt solution for later use. Then, 4-hydroxyisophthalic acid, ethanol solution and diazonium salt solution were mixed and reacted at room temperature under ice-water bath conditions to obtain a UV absorber precursor. Finally, the UV absorber precursor was reduced with sodium dithionite under alkaline conditions and then acidified to obtain the UV absorber. Adding ethyl acetoacetate methacrylate and styrene during the preparation of polyacrylate emulsions improves the leveling and adhesion of the finished water-based inks by introducing flexible segments of ethyl acetoacetate methacrylate and prevents the penetration of organic solvents after crosslinking with the curing agent. The rigid benzene ring structure of the introduced styrene can increase the steric hindrance between polyacrylate emulsion molecules. The curing agent has a double-ended hydrazide structure, which can react and crosslink with the carbonyl group of ethyl acetoacetate at room temperature. The curing agent also has a benzotriazole UV absorber structure, which links the UV absorber to the polyacrylate molecular chain through chemical crosslinking.

2. The water-based ink according to claim 1, characterized in that, The emulsifier is one or a mixture of two of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate, the initiator is ammonium persulfate, the defoamer is one or a mixture of one or more of BYK-024, BYK-028, and DC-57, and the leveling agent is one or a mixture of one or more of EFKA-3777 and TEGO Rad 2700.

3. The water-based ink according to claim 1, characterized in that, The hydrazine hydrate solution is an 80% (w / w) aqueous solution of hydrazine hydrate, and the ratio of ultraviolet absorber to hydrazine hydrate used is 5.6–6 g: 4–8 g.

4. The water-based ink according to claim 1, characterized in that, The concentrated hydrochloric acid used has a mass fraction of 30-38%, the sodium nitrite solution used is prepared by 5.5-6.9g of sodium nitrite and 30-40mL of deionized water, the ethanol solution used is an aqueous ethanol solution with a volume fraction of 40-95%, and the sodium hydroxide solution used is an aqueous sodium hydroxide solution with a mass fraction of 15-25%.

5. The water-based ink according to claim 1, characterized in that, The ratio of 2-nitroaniline to sodium nitrite solution used is 6.9–8.3 g: 30–40 mL; the ratio of 4-hydroxyisophthalic acid to diazonium salt solution used is 6.9–7.7 g: 100–110 mL; and the ratio of UV absorber precursor to sodium dithionite used is 9.2–10.4 g: 14–20 g.

6. A method for preparing a water-based ink as described in any one of claims 1 to 5, characterized in that, Includes the following steps: An initiator solution is prepared by mixing an initiator with a portion of deionized water. Then, an emulsifier, ethyl acetoacetate methacrylate, methyl methacrylate, styrene, butyl acrylate, acrylic acid, sodium bicarbonate, and the remaining deionized water are added to a container and mixed to obtain an emulsion. The initiator solution is then added to the emulsion and the reaction is carried out at a controlled temperature of 75–90°C to obtain a polyacrylate emulsion. Finally, the polyacrylate emulsion is mixed with a defoamer, leveling agent, pigment, and curing agent to obtain a water-based ink.

7. The method for preparing a water-based ink according to claim 6, characterized in that, The ratio of initiator to deionized water used in the second step, by mass fraction, is 0.1–0.3:4–10.

8. The method for preparing a water-based ink according to claim 6, characterized in that, The conditions for stirring and dispersing in the third step are to stir at a speed of 300-400 rpm for 20-40 minutes.

9. The method for preparing a water-based ink according to claim 6, characterized in that, The fourth step involves stirring at 100–200 rpm for 60–100 minutes to achieve uniform mixing.

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