Water-based ink and preparation method thereof

Abstract

The invention discloses water-based ink and a preparation method thereof. The invention relates to printing ink and a preparation method thereof, and belongs to the technical field of printing ink. According to the invention, acetoacetoxy ethyl methacrylate and styrene are added during preparation of polyacrylate, so that the leveling property and adhesive force of the finished product water-based ink are improved, and the wear resistance and hydrophobic property of the finished product oil ink are improved; the curing agent can be cross-linked with carbonyl in acetoacetoxy ethyl methacrylate at normal temperature, the curing speed of the water-based ink at low temperature is increased, the chemical resistance and weather resistance of the water-based ink are improved, the surface drying time of the water-based ink at low temperature (10 DEG C) can be lower than 25 s, and the water-based ink has good water-based ink surface drying performance. And the printing speed requirement of modern enterprises can be met.

Description

Technical Field

[0001] The present invention belongs to the technical field of printing inks, and in particular relates to a water-based ink and a preparation method thereof. Background Art

[0002] Water-based ink is a printing material with water as its primary solvent. Its core components include water-based resins, pigments, additives (such as defoamers and dispersants), and water. Compared to traditional solvent-based inks, water-based inks contain far lower levels of volatile organic compounds (VOCs), significantly reducing harm to the human body. They are safe, non-toxic, and environmentally friendly. However, water has a higher boiling point than most common solvents, and the curing of water-based inks relies heavily on the volatilization of water. This results in a slower surface drying rate than traditional solvent-based inks. This is particularly true in winter, when temperatures are low, as the drying efficiency of water-based inks is significantly reduced. Failure to dry the surface of water-based inks in a timely manner can lead to color stacking and blurred prints, necessitating reduced printing speeds and the addition of thermal or infrared drying equipment. Therefore, the present invention provides a water-based ink and a method for its preparation. Summary of the Invention

[0003] The object of the present invention is to provide a water-based ink and a preparation method thereof, so as to solve the problems mentioned in the above background technology.

[0004] The purpose of the present invention can be achieved through the following technical solutions: A water-based ink comprising the following raw materials: 1-3 parts of an emulsifier, 2-4 parts of ethyl acetoacetate, 12-18 parts of methyl methacrylate, 5-10 parts of styrene, 20-25 parts of butyl acrylate, 0.3-0.6 parts of acrylic acid, 0.1-0.5 parts of sodium bicarbonate, 0.1-0.3 parts of an initiator, 40-60 parts of deionized water, 0.2-0.4 parts of a defoaming agent, 0.3-0.5 parts of a leveling agent, 8-20 parts of a pigment, and 1-4 parts of a curing agent; A method for preparing a water-based ink comprises the following steps: The first step is to weigh each raw material according to the mass fraction; The second step is to prepare an initiator solution by mixing the initiator and a portion of deionized water; Step 3: Add the emulsifier, ethyl acetoacetate, methyl methacrylate, styrene, butyl acrylate, acrylic acid, sodium bicarbonate and the remaining deionized water into an emulsifier, stir and disperse, and mix to obtain an emulsion; The fourth step is to add the initiator solution dropwise into the emulsion, heat it to 75-90°C and react for 80-120 minutes to obtain a polyacrylate emulsion, then cool the polyacrylate emulsion to 30-50°C, add a defoamer, a leveling agent, a pigment, and a curing agent, and stir evenly to obtain a water-based ink.

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

[0006] Furthermore, the initiator is ammonium persulfate.

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

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

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

[0010] Furthermore, the stirring and dispersing condition in the third step is stirring at a rotation speed of 300 to 400 rpm for 20 to 40 minutes.

[0011] Furthermore, the stirring condition in the fourth step is to stir uniformly at a rotation speed of 100 to 200 rpm for 60 to 100 minutes.

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

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

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

[0015] Furthermore, the UV absorber has the following structure , and can be made by the following steps: Step 1: Mix 2-nitroaniline, concentrated hydrochloric acid, and deionized water in a three-necked flask under an ice-water bath, start magnetic stirring, then dropwise add sodium nitrite solution to the three-necked flask. After the addition is complete, react in an ice-water bath for 30 to 60 minutes. After the reaction is complete, add urea to the reaction solution so that the reaction solution no longer turns starch potassium iodide test paper blue. Then filter to obtain a diazonium salt solution, and refrigerate at 0°C for later use. Step 2: Mix 4-hydroxyisophthalic acid and ethanol solution in a three-necked flask under ice-water bath conditions, start magnetic stirring, and dropwise add the diazonium salt solution into the three-necked flask. After the addition is complete, remove the ice-water bath and react at room temperature for 2 to 6 hours. After the reaction is complete, vacuum filter and wash the obtained solid with deionized water and dry it to obtain a UV absorber precursor; Step 3: Mix the ultraviolet absorber precursor, ethanol solution, and sodium hydroxide solution in a three-necked flask, start magnetic stirring, heat to reflux, add sodium dithionite to the three-necked flask, and continue to react under reflux conditions for 1 to 2 hours. After the reaction is completed, pour the reaction solution into ice water to cool, and acidify it with hydrochloric acid to pH 3 to 5, then vacuum filter, wash the obtained solid with deionized water and dry it to obtain the ultraviolet absorber.

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

[0017] Furthermore, the sodium nitrite solution used in step 1 is prepared from 5.5-6.9 g of sodium nitrite and 30-40 mL of deionized water.

[0018] Furthermore, the amount 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 step 2 and step 3 is an ethanol aqueous solution with a volume fraction of 40 to 95%.

[0020] Furthermore, the amount 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 a sodium hydroxide aqueous solution with a mass fraction of 15 to 25%.

[0022] Furthermore, the amount ratio of the 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] Beneficial effects of the present invention: 1) In the present invention, acetoacetoxyethyl methacrylate and styrene are added during the preparation of the polyacrylate emulsion. The introduced flexible chain segments of acetoacetoxyethyl methacrylate can improve the leveling and adhesion of the finished water-based ink and, after cross-linking with the curing agent, prevent the penetration of organic solvents, thereby improving the chemical resistance of the finished ink. The introduced rigid benzene ring structure of styrene can increase the chain segment steric hindrance between the molecules of the polyacrylate emulsion, thereby improving the wear resistance and hydrophobicity of the polyacrylate emulsion and accelerating the drying speed of the finished water-based ink.

[0024] 2) The present invention uses 2-nitroaniline and sodium nitrite as raw materials, and utilizes the strong oxidizing property of sodium nitrite in a strong acid medium to undergo a diazotization reaction with 2-nitroaniline to obtain a diazonium salt solution, and then the diazonium salt solution undergoes a coupling reaction at the ortho position of the hydroxyl group of 4-hydroxyisophthalic acid dimethyl ester to obtain a UV absorber precursor, and then the UV absorber is reduced and cyclized with a reducing agent, sodium dithionite, to obtain a UV absorber, and finally hydrazine hydrate is used to undergo a nucleophilic substitution reaction with the UV absorber to obtain a curing agent. The curing agent of the present invention has a double-ended hydrazide structure, which can react and cross-link with the carbonyl group of acetoacetoxyethyl methacrylate at room temperature, accelerate the curing speed of water-based ink under low temperature conditions, and broaden the application scenarios of water-based ink. In addition, the curing agent also has a benzotriazole UV absorber structure, which can connect the UV absorber to the polyacrylate molecular chain in a chemical cross-linking manner. After curing and cross-linking, the active ingredients are not easy to migrate, and the finished water-based ink can have long-term weather resistance.

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

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

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

[0028] Wherein, the curing agent is prepared by the following steps: Step 1: Mix 6.9 g of 2-nitroaniline, 30 mL of 38% concentrated hydrochloric acid, and 40 mL of deionized water in a three-necked flask under ice-water bath conditions, start magnetic stirring, and then dropwise add a solution prepared by 5.5 g of sodium nitrite and 40 mL of deionized water into the three-necked flask. After the addition is complete, react in an ice-water bath for 30 minutes. After the reaction is complete, add urea to the reaction solution so that the reaction solution no longer turns the starch potassium iodide test paper blue. Then filter to obtain a diazonium salt solution, which is refrigerated at 0°C for later use. Step 2: 6.9 g of 4-hydroxyisophthalic acid and 40 mL of 95% by volume ethanol aqueous solution were mixed in a three-necked flask under ice-water bath conditions, and 100 mL of diazonium salt solution was added dropwise to the three-necked flask under magnetic stirring. After the addition was complete, the ice-water bath was removed and the mixture was reacted at room temperature for 2 h. After the reaction was completed, vacuum filtration was performed, and the obtained solid was washed with deionized water and dried to obtain a UV absorber precursor; Step 3: 9.2 g of ultraviolet absorber precursor, 60 mL of 95% by volume ethanol aqueous solution, and 50 mL of 25% by mass sodium hydroxide aqueous solution were mixed in a three-necked flask, magnetic stirring was turned on, and after heating to reflux, 14 g of sodium dithionite was added to the three-necked flask, and the reaction was continued under reflux conditions for 1 hour. After the reaction was completed, the reaction solution was poured into ice water to cool, and acidified to pH 3 with hydrochloric acid, and then vacuum filtered. The obtained solid was washed with deionized water and dried to obtain the ultraviolet absorber; Step 4: 5.6 g of ultraviolet absorber and 40 mL of anhydrous ethanol were mixed in a three-necked flask, a condenser and a thermometer were installed, magnetic stirring was turned on, and the temperature was heated to 80° C. After that, 4 g of 80% by mass hydrazine hydrate solution was added to the three-necked flask, and the mixture was reacted at a temperature of 80° C. for 8 h. After the reaction was completed, the mixture was cooled in an ice-water bath, and then vacuum filtered. The obtained solid was washed with deionized water and dried to obtain the curing agent.

[0029] The preparation method of the water-based ink comprises the following steps: The first step is to weigh each raw material according to the mass fraction; Step 2: Prepare an initiator solution by mixing the initiator with 4 parts of deionized water; Step 3: Add the emulsifier, ethyl acetoacetate, methyl methacrylate, styrene, butyl acrylate, acrylic acid, sodium bicarbonate and the remaining deionized water into an emulsifier and stir at 300 rpm for 40 minutes to obtain an emulsion; Step 4: Add the initiator solution dropwise to the emulsion, heat it to 75°C, and react for 120 minutes to obtain a polyacrylate emulsion. Then, cool the polyacrylate emulsion to 30°C, add a defoamer, a leveling agent, a pigment, and a curing agent, and stir at a speed of 100 rpm for 100 minutes to obtain a water-based ink.

[0030] The emulsifier used in this embodiment is sodium lauryl 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 of an emulsifier, 3 parts of ethyl acetoacetate, 15 parts of methyl methacrylate, 7.5 parts of styrene, 22.5 parts of butyl acrylate, 0.45 parts of acrylic acid, 0.3 parts of sodium bicarbonate, 0.2 parts of an initiator, 50 parts of deionized water, 0.3 parts of a defoaming agent, 0.4 parts of a leveling agent, 14 parts of a pigment, and 2.5 parts of a curing agent.

[0032] Wherein, the curing agent is prepared by the following steps: Step 1: Mix 7.6 g of 2-nitroaniline, 40 mL of 35% concentrated hydrochloric acid, and 35 mL of deionized water in a three-necked flask under ice-water bath conditions, start magnetic stirring, and then dropwise add a solution prepared by 6.2 g of sodium nitrite and 40 mL of deionized water into the three-necked flask. After the addition is complete, react in an ice-water bath for 45 minutes. After the reaction is complete, add urea to the reaction solution so that the reaction solution no longer turns the starch potassium iodide test paper blue. Then filter to obtain a diazonium salt solution, which is refrigerated at 0°C for later use. Step 2: 7.3 g of 4-hydroxyisophthalic acid and 60 mL of a 70% volume fraction ethanol aqueous solution were mixed in a three-necked flask under ice-water bath conditions, and magnetic stirring was turned on. 105 mL of the diazonium salt solution was added dropwise to the three-necked flask. After the addition was complete, the ice-water bath was removed and the mixture was reacted at room temperature for 4 h. After the reaction was completed, vacuum filtration was performed, and the obtained solid was washed with deionized water and dried to obtain a UV absorber precursor; Step 3: 9.8 g of ultraviolet absorber precursor, 80 mL of 70% by volume ethanol aqueous solution, and 75 mL of 20% by mass sodium hydroxide aqueous solution were mixed in a three-necked flask, magnetic stirring was turned on, and after heating to reflux, 17 g of sodium dithionite was added to the three-necked flask, and the reaction was continued under reflux for 1.5 hours. After the reaction was completed, the reaction solution was poured into ice water to cool, and acidified to pH 4 with hydrochloric acid, and then vacuum filtered. The obtained solid was washed with deionized water and dried to obtain the ultraviolet absorber; Step 4: 5.8 g of ultraviolet absorber and anhydrous ethanol were mixed in a three-necked flask, a condenser and a thermometer were installed, magnetic stirring was turned on, and the temperature was heated to 80° C. After that, 6 g of 80% by mass hydrazine hydrate solution was added to the three-necked flask, and the mixture was reacted at a temperature of 80° C. for 10 hours. After the reaction was completed, the mixture was cooled in an ice-water bath, and then vacuum filtered. The obtained solid was washed with deionized water and dried to obtain the curing agent.

[0033] The preparation method of the water-based ink comprises the following steps: The first step is to weigh each raw material according to the mass fraction; Step 2: Prepare an initiator solution by mixing the initiator with 7 parts of deionized water; Step 3: Add the emulsifier, ethyl acetoacetate, methyl methacrylate, styrene, butyl acrylate, acrylic acid, sodium bicarbonate and the remaining deionized water into an emulsifier and stir at 350 rpm for 30 min to obtain an emulsion; Step 4: Add the initiator solution dropwise into the emulsion, heat it to 83°C, and react for 100 minutes to obtain a polyacrylate emulsion. Then, cool the polyacrylate emulsion to 40°C, add a defoamer, a leveling agent, a pigment, and a curing agent, and stir at 150 rpm for 80 minutes to obtain a water-based ink.

[0034] The emulsifier used in this embodiment is sodium lauryl 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 of an emulsifier, 4 parts of ethyl acetoacetate, 18 parts of methyl methacrylate, 10 parts of styrene, 25 parts of butyl acrylate, 0.6 parts of acrylic acid, 0.5 parts of sodium bicarbonate, 0.3 parts of an initiator, 60 parts of deionized water, 0.4 parts of a defoaming agent, 0.5 parts of a leveling agent, 20 parts of a pigment, and 4 parts of a curing agent.

[0036] Wherein, the curing agent is prepared by the following steps: Step 1: Mix 8.3 g of 2-nitroaniline, 50 mL of 30% concentrated hydrochloric acid, and 30 mL of deionized water in a three-necked flask under ice-water bath conditions, start magnetic stirring, and then dropwise add a solution prepared by 6.9 g of sodium nitrite and 40 mL of deionized water into the three-necked flask. After the addition is complete, react in an ice-water bath for 60 minutes. After the reaction is complete, add urea to the reaction solution so that the reaction solution no longer turns the starch potassium iodide test paper blue. Then filter to obtain a diazonium salt solution, which is refrigerated at 0°C for later use. Step 2: Mix 6.9-7.7 g of 4-hydroxyisophthalic acid and 40-80 mL of 40-95% ethanol aqueous solution in a three-necked flask under ice-water bath conditions, turn on magnetic stirring, and dropwise add 110 mL of diazonium salt solution to the three-necked flask. After the addition is complete, remove the ice-water bath and react at room temperature for 6 hours. After the reaction is completed, vacuum filter and wash the obtained solid with deionized water and dry it to obtain a UV absorber precursor; Step 3: 10.4 g of ultraviolet absorber precursor, 100 mL of 40% by volume ethanol aqueous solution, and 50 mL of 25% by mass sodium hydroxide aqueous solution were mixed in a three-necked flask, magnetic stirring was turned on, and after heating to reflux, 20 g of sodium dithionite was added to the three-necked flask, and the reaction was continued under reflux conditions for 2 hours. After the reaction was completed, the reaction solution was poured into ice water to cool, and acidified to pH 5 with hydrochloric acid, and then vacuum filtered. The obtained solid was washed with deionized water and dried to obtain the ultraviolet absorber; Step 4: 6 g of ultraviolet absorber and anhydrous ethanol were mixed in a three-necked flask, a condenser and a thermometer were installed, magnetic stirring was turned on, and the temperature was heated to 80° C., 8 g of 80% by mass hydrazine hydrate solution was added to the three-necked flask, and the mixture was reacted at a temperature of 80° C. for 12 h. After the reaction was completed, the mixture was cooled in an ice-water bath, and then vacuum filtered. The obtained solid was washed with deionized water and dried to obtain the curing agent.

[0037] The preparation method of the water-based ink comprises the following steps: The first step is to weigh each raw material according to the mass fraction; Step 2: Prepare an initiator solution by mixing the initiator with 10 parts of deionized water; Step 3: Add the emulsifier, ethyl acetoacetate, methyl methacrylate, styrene, butyl acrylate, acrylic acid, sodium bicarbonate and the remaining deionized water into an emulsifier and stir at 400 rpm for 20 min to obtain an emulsion; Step 4: Add the initiator solution dropwise into the emulsion, heat it to 90°C, and react for 80 minutes to obtain a polyacrylate emulsion. Then, cool the polyacrylate emulsion to 50°C, add a defoamer, a leveling agent, a pigment, and a curing agent, and stir at 200 rpm for 60 minutes to obtain a water-based ink.

[0038] The emulsifier used in this embodiment 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 by the present invention is not used, and a conventional ultraviolet absorber is used instead.

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

[0041] The preparation method of the water-based ink comprises the following steps: The first step is to weigh each raw material according to the mass fraction; Step 2: Prepare an initiator solution by mixing the initiator with 7 parts of deionized water; Step 3: Add the emulsifier, ethyl acetoacetate, methyl methacrylate, styrene, butyl acrylate, acrylic acid, sodium bicarbonate and the remaining deionized water into an emulsifier and stir at 350 rpm for 30 min to obtain an emulsion; Step 4: Add the initiator solution dropwise into the emulsion, heat it to 83°C, and react for 100 minutes to obtain a polyacrylate emulsion. Then, cool the polyacrylate emulsion to 40°C, add a defoamer, a leveling agent, a pigment, and an ultraviolet absorber, and stir at 150 rpm for 80 minutes to obtain a water-based ink.

[0042] Among them, the emulsifier used in this comparative example is sodium lauryl sulfate, the initiator used is ammonium persulfate, the defoamer used is BYK-028, the leveling agent used is EFKA-3777, and the ultraviolet absorber used is Tinuvin P.

[0043] Comparative Example 2 This comparative example is a commercially available water-based ink.

[0044] Experimental Example 1 The performance tests were conducted on the water-based inks in Examples 1 to 3 and Comparative Example 1, as well as the commercially available water-based ink in Comparative Example 2. The surface drying time of each component of the water-based ink was tested at a temperature of 10°C according to GB / T9278-2008, and the light fastness 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 use of the curing agent of the present invention can effectively improve the UV resistance of the water-based ink and increase the surface-drying time at low temperatures. The surface-drying time of the water-based ink of the present invention is less than 25 seconds, which can meet the printing speed requirements of modern enterprises.

[0046] The above is a detailed introduction to a water-based ink and a preparation method thereof provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enables any technician in the field to practice the present invention, including the manufacture and use of any device or system, and the implementation of any combination method. It should be pointed out that for ordinary technicians in this technical field, the present invention can also be improved and modified in a number of ways without departing from the principles of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed in the present invention can be combined with each other in any way. The fact that these combinations are not exhaustively described in this specification is simply for the sake of omitting space and saving resources. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A water-based ink, characterized in that: The invention comprises the following raw materials in parts by weight: 1 to 3 parts of emulsifier, 2 to 4 parts of ethyl acetoacetate, 12 to 18 parts of methyl methacrylate, 5 to 10 parts of styrene, 20 to 25 parts of butyl acrylate, 0.3 to 0.6 parts of acrylic acid, 0.1 to 0.5 parts of sodium bicarbonate, 0.1 to 0.3 parts of initiator, 40 to 60 parts of deionized water, 0.2 to 0.4 parts of defoaming agent, 0.3 to 0.5 parts of leveling agent, 8 to 20 parts of pigment, and 1 to 4 parts of curing agent; Wherein, the curing agent is prepared by the following steps: After the ultraviolet absorber is dissolved in anhydrous ethanol and heated to 80°C, a hydrazine hydrate solution is added to the system and the reaction is continued at 80°C to obtain a curing agent; Among them, the ultraviolet absorber has the following structure: .

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

3. A water-based ink according to claim 1, characterized in that: The hydrazine hydrate solution is an 80% by mass hydrazine hydrate aqueous solution, and the amount ratio of the ultraviolet absorber to the hydrazine hydrate is 5.6-6g:4-8g.

4. A water-based ink according to claim 1, characterized in that: The ultraviolet absorber is prepared by the following steps: 2-nitroaniline and sodium nitrite solution are mixed and reacted in a strong acid medium under ice-water bath conditions to obtain a diazonium salt solution for standby use. Subsequently, 4-hydroxyisophthalic acid, ethanol solution, and diazonium salt solution are mixed under ice-water bath conditions and reacted at room temperature to obtain a UV absorber precursor. Finally, the UV absorber precursor is reduced with sodium dithionite under alkaline conditions and then acidified to obtain the UV absorber.

5. A water-based ink according to claim 1 or 4, characterized in that: The mass fraction of the concentrated hydrochloric acid used is 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 ethanol aqueous solution with a volume fraction of 40-95%, and the sodium hydroxide solution used is a sodium hydroxide aqueous solution with a mass fraction of 15-25%.

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

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

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

9. The method for preparing a water-based ink according to claim 7, characterized in that: The stirring and dispersing conditions in the third step are stirring at a rotation speed of 300 to 400 rpm for 20 to 40 minutes.

10. The method for preparing a water-based ink according to claim 7, characterized in that: The stirring condition in the fourth step is to stir uniformly at a rotation speed of 100 to 200 rpm for 60 to 100 minutes.

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