Water-soluble UV inkjet ink and preparation method thereof

Abstract

The invention discloses water-soluble UV ink-jet ink and a preparation method thereof, and belongs to the technical field of ink-jet printing ink preparation. The water-soluble UV ink-jet ink is prepared from the following raw materials in percentage by weight: 30 to 40 percent of polyester type polyurethane prepolymer coated leavening agent emulsion, 38.4 to 57.7 percent of acrylate monomer, 4 to 7 percent of photoinitiator, 8 to 14 percent of water-soluble dye, 0.3 to 0.6 percent of organic silicon flatting agent and 0 to 0.1 percent of surfactant. According to the invention, an inorganic chemical leavening agent is coated by emulsion polymerization to form a polyacrylate emulsion-coated leavening agent emulsion, and then the polyacrylate emulsion-coated leavening agent emulsion is polymerized with diisocyanate and polyester polyol to form a polyester type polyurethane prepolymer-coated leavening agent emulsion; and finally, mixing and stirring with an acrylate monomer, a photoinitiator, a water-soluble dye and an organic silicon flatting agent to form the water-soluble UV ink-jet ink, thereby achieving the purpose that the ink is easy to clean and remove after printing.

Description

Technical Field

[0001] The invention belongs to the technical field of inkjet printing ink preparation, and particularly relates to a water-soluble UV inkjet ink and a preparation method thereof. Background Art

[0002] With the rapid development of digital printing technology, UV inkjet ink, as an emerging printing material, has gradually occupied an important position in various printing applications. UV inkjet ink is mainly composed of the following components: (1) Resin: Resin is one of the main components of UV ink and determines the adhesion, wear resistance and gloss of the ink. Common types of resins include acrylic resin, polyurethane resin and epoxy resin; (2) Monomer: Monomer is a low molecular weight compound that participates in the polymerization reaction and can quickly polymerize to form a solid under UV light irradiation. Common monomers include acrylic monomers and vinyl monomers; (3) Photoinitiator: Photoinitiator is an indispensable component of UV ink. Its function is to absorb UV light and generate free radicals, thereby initiating polymerization reaction. Common photoinitiators include styrene, ketone and phenyl; (4) Additives: In order to improve the performance of the ink, various additives (such as anti-precipitation agents, leveling agents, antioxidants, UV inhibitors, etc.) are added according to the actual needs of use to enhance the stability of the ink and the printing effect.

[0003] The core of UV inkjet technology lies in the ink curing process. After the UV ink is sprayed onto the surface of the substrate through the nozzle, the ink is irradiated with a UV light source. The photoinitiator absorbs the light energy and generates free radicals. These free radicals trigger a polymerization reaction between the resin and the monomer, quickly converting the liquid ink into a solid film. This process has the following significant advantages: (1) Rapid curing: UV ink cures extremely quickly, usually within a few seconds, greatly improving printing efficiency; (2) High adhesion: Because the curing process occurs on the surface of the substrate, the ink can form good adhesion with the substrate, ensuring the durability of the printed pattern; (3) Environmental protection: Solvent-free formulas are often used in UV inkjet inks, which reduces the emission of volatile organic compounds (VOCs) and meets modern environmental protection requirements.

[0004] UV inkjet technology is widely used in various fields due to its advantages of high efficiency, high quality and environmental protection: (1) Packaging and printing: UV inkjet ink is widely used in printing various packaging materials, such as food packaging and cosmetic packaging. Its wear resistance, water resistance and oil resistance make it the preferred material in the packaging industry; (2) Advertising and logo: In the advertising industry, UV inkjet ink can be used for high-quality printing on different materials, such as PVC, acrylic, glass and metal, to meet the needs of various billboards, banners and logos; (3) Interior decoration: With the increasing demand for personalized home furnishings, UV inkjet technology has also been applied to interior decoration, such as printing on walls, floors and furniture. Its rich selection of colors and patterns can meet consumers' pursuit of personalized design; (4) Electronics industry: UV inkjet ink has also been widely used in components such as electronic product housings, buttons and display panels. Its high temperature resistance and corrosion resistance can ensure the stability and reliability of electronic products during use.

[0005] Although UV inkjet ink has many advantages, in actual use in certain fields (such as packaging printing and advertising slogan printing), inkjet printing requires adjustment of various parameters such as ink concentration, printing distance, and printing size. In addition, if errors are found in printed patterns or text, reprinting and adjustment are required. During this process, conventional UV inkjet ink cannot be effectively scrubbed off. This inevitably makes it difficult to easily remove the ink from the surface of the substrate previously printed and reuse it, resulting in waste of substrate material.

[0006] Therefore, it is of practical application value to study a UV inkjet ink that is easy to remove by cleaning. Summary of the Invention

[0007] In response to the shortcomings of the prior art, the present invention addresses the technical problems raised in the background art by using emulsion polymerization to coat an inorganic chemical leavening agent to form a polyacrylate emulsion coated with the leavening agent emulsion, which is then polymerized with diisocyanate and polyester polyol to form a polyester polyurethane prepolymer coated with the leavening agent emulsion. Finally, the prepolymer is mixed and stirred with an acrylate monomer, a photoinitiator, a water-soluble dye, and an organosilicon leveling agent to form a water-soluble UV inkjet ink. Specifically, the technical solution of the present invention includes the following: One of the purposes of the present invention is to provide a water-soluble UV inkjet ink, wherein the water-soluble UV inkjet ink comprises the following raw materials in percentage by weight: 30%~40% polyester polyurethane prepolymer coated leavening agent emulsion, 38.4%~57.7% acrylate monomer, 4%~7% photoinitiator, 8%~14% water-soluble dye, 0.3%~0.6% silicone leveling agent and 0~0.1% surfactant.

[0008] Furthermore, the preparation method of the polyester polyurethane prepolymer coated leavening agent emulsion comprises the following steps: An emulsifier, an inorganic chemical leavening agent and deionized water are mixed in a weight ratio of 0.01:4-5:150-200 and then ultrasonically dispersed to form a dispersed slurry; The dispersed slurry, hydroxyl acrylate monomer and potassium persulfate are mixed in a weight ratio of 100:30-50:0.13-0.3, heated to 65° C.-70° C. and reacted for 3 h-5 h to obtain a polyacrylate emulsion-coated leavening agent emulsion; The polyacrylate emulsion-coated leavening agent emulsion, diisocyanate, polyester polyol and dibutyltin dilaurate are mixed in a weight ratio of 15-16:7-11:10-12:0.02-0.03, heated to 75° C.-80° C. and reacted for 1.5 h-2.5 h to obtain the polyester polyurethane prepolymer-coated leavening agent emulsion.

[0009] Furthermore, the emulsifier includes sodium dodecyl sulfate or sodium dodecylbenzene sulfonate.

[0010] Furthermore, the ultrasonic dispersion conditions include ultrasonic power of 300W to 400W and ultrasonic time of 10min to 15min.

[0011] Furthermore, the inorganic chemical leavening agent includes nano calcium carbonate or nano magnesium carbonate.

[0012] Furthermore, the hydroxy acrylate monomer includes hydroxypropyl acrylate or hydroxyethyl methacrylate.

[0013] Furthermore, the diisocyanate includes isophorone diisocyanate or hexamethylene diisocyanate.

[0014] Furthermore, the polyester polyol includes phthalic anhydride polyester polyol HF-8031 or phthalic anhydride polyester polyol HF-8056.

[0015] Furthermore, the acrylate monomer includes 1,6-hexanediol diacrylate, neopentyl glycol diacrylate or dipropylene glycol diacrylate.

[0016] Furthermore, the photoinitiator includes photoinitiator 907, photoinitiator 1173, photoinitiator 184 or photoinitiator 819.

[0017] Furthermore, the water-soluble dye includes Basic Violet 10, Acid Yellow 23 or Acid Red 18.

[0018] Furthermore, the organosilicon leveling agent includes leveling agent WT 4116 or leveling agent WT 4117.

[0019] Furthermore, the surfactant includes polyvinyl alcohol.

[0020] A second object of the present invention is to provide a method for preparing a water-soluble UV inkjet ink, the method comprising the following steps: The polyester polyurethane prepolymer coated leavening agent emulsion and the acrylate monomer are mixed, heated to 40° C. to 50° C. and stirred for 20 min to 30 min, then the water-soluble dye, silicone leveling agent and surfactant are added and stirred for 20 min to 30 min, and finally the photoinitiator is added and stirred in a light-proof environment for 30 min to 40 min to obtain the water-soluble UV inkjet ink.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The present invention utilizes inorganic chemical leavening agents (nano-calcium carbonate and nano-magnesium carbonate) that can release carbon dioxide gas under acidic conditions to achieve expansion. The inorganic chemical leavening agents are first pretreated to form a dispersed slurry. Then, by utilizing the advantages of emulsion polymerization coating, an acrylic acid hydroxyl ester monomer having a hydroxyl group and a carbon-carbon double bond is used as a polymerization encapsulation monomer. Under the catalysis of an initiator potassium persulfate, the inorganic chemical leavening agent is polymerized and coated to form a polyacrylate emulsion encapsulating the leavening agent emulsion. This not only achieves the encapsulation of the inorganic chemical leavening agent, but also solves the problem that simply adding an inorganic chemical leavening agent will cause agglomeration and uneven dispersion, necessitating the additional addition of a dispersant, and the introduction of the dispersant will increase the viscosity of the finally prepared UV inkjet ink, thereby reducing the ink printing efficiency. The polyacrylate emulsion coated leavening agent emulsion and diisocyanate and polyester polyol are polymerized under the catalysis of dibutyltin dilaurate to form a polyester polyurethane prepolymer coated leavening agent emulsion, which is then mixed and stirred with acrylate monomer, photoinitiator, water-soluble dye, silicone leveling agent and surfactant to form a water-soluble UV inkjet ink. Compared with the polyether polyurethane prepolymer-coated leavening agent emulsion prepared using polyethylene glycol, the polyester polyurethane prepolymer-coated leavening agent emulsion does not contain structurally stable and hydrolysis-resistant ether bonds. Therefore, the water-soluble UV inkjet ink prepared by the present invention is immersed in a hot acetic acid solution after printing, cross-linking, curing and drying. The hot acetic acid solution can not only partially hydrolyze the ester bonds and urea bonds in the polyester polyurethane, thereby promoting the cross-linking and curing structure of the water-soluble UV inkjet ink, but also enable the acetic acid solution to further react with the polymer-coated inorganic chemical leavening agent to generate carbon dioxide gas, thereby causing the surface of the dry ink formed after printing and curing to bulge, breaking away from the stickiness to the printed base material, so that the ink can be easily removed after finally rinsing and rubbing with water. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions of the present invention through 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 those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0023] Unless otherwise specified, the raw materials and reagents used in the present invention are commercially available or can be prepared by known methods.

[0024] Nano calcium carbonate and nano magnesium carbonate were purchased from Shijiazhuang Jinghuang Technology Co., Ltd. Silicone leveling agent WT 4116, WT 4117 Guangzhou Yangsong Trading Co., Ltd. Basic Violet 10, Acid Yellow 23, Acid Red 18, and Pigment Red 254 were purchased from Shanghai Jingyan Chemical Co., Ltd.; Phthalic anhydride polyester polyol HF-8031, Phthalic anhydride polyester polyol HF-8056 Huafeng Group Co., Ltd.

[0025] Preparation Example 1: The preparation of polyester polyurethane prepolymer coated leavening agent emulsion specifically includes the following processes: Weigh 4 parts by weight of nano-calcium carbonate and 150 parts by weight of deionized water, mix and stir, then add 0.01 parts by weight of sodium lauryl sulfate, and then perform ultrasonic dispersion treatment at room temperature with an ultrasonic power of 300W for 10 minutes. Weigh 100 parts by weight of the ultrasonically dispersed dispersion slurry and add it to the reactor, then take 30 parts by weight of hydroxypropyl acrylate and 0.13 parts by weight of potassium persulfate and add them to the above reactor to mix with the dispersion slurry. At this time, nitrogen is introduced into the reactor to exhaust the air in the reactor, the reactor is closed, and the reactor is heated to 65°C and the reaction time is 3 hours. After the reaction is completed, it is naturally cooled to room temperature to obtain a polyacrylate emulsion coated with a leavening agent emulsion; 15 parts by weight of a polyacrylate emulsion-coated leavening agent emulsion was weighed and placed into a reactor and stirred at 100 rpm. Then, 7 parts by weight of isophorone diisocyanate, 10 parts by weight of phthalic anhydride polyester polyol HF-8031, and 0.02 parts by weight of dibutyltin dilaurate were added to the reactor and mixed with the polyacrylate emulsion-coated leavening agent emulsion. Nitrogen was then introduced into the reactor as a protective gas. The reactor was then heated to 75°C and the reaction timed for 1.5 hours. After the reaction was complete, the mixture was poured out while hot and allowed to cool naturally to obtain a polyester-type polyurethane prepolymer-coated leavening agent emulsion.

[0026] Preparation Example 2: The preparation of polyester polyurethane prepolymer coated leavening agent emulsion specifically includes the following processes: Weigh 4.4 parts by weight of nano-calcium carbonate and 170 parts by weight of deionized water, mix and stir, then add 0.01 parts by weight of sodium lauryl sulfate, and then perform ultrasonic dispersion treatment at room temperature with an ultrasonic power of 350W for 12 minutes. Weigh 100 parts by weight of the ultrasonically dispersed dispersion slurry and add it to the reactor, then take 40 parts by weight of hydroxypropyl acrylate and 0.2 parts by weight of potassium persulfate and add them to the above reactor to mix with the dispersion slurry. At this time, nitrogen is introduced into the reactor to exhaust the air in the reactor, the reactor is closed, and the reactor is heated to 65°C and the reaction time is 4 hours. After the reaction is completed, it is naturally cooled to room temperature to obtain a polyacrylate emulsion coated with a leavening agent emulsion; 15 parts by weight of a polyacrylate emulsion-coated leavening agent emulsion was weighed and placed into a reactor and stirred at 100 rpm. Then, 9 parts by weight of isophorone diisocyanate, 11 parts by weight of phthalic anhydride polyester polyol HF-8031, and 0.025 parts by weight of dibutyltin dilaurate were added to the reactor and mixed with the polyacrylate emulsion-coated leavening agent emulsion. Nitrogen was then introduced into the reactor as a protective gas. The reactor was then heated to 75°C and the reaction timed for 2 hours. After the reaction was completed, the mixture was poured out while hot and allowed to cool naturally to obtain a polyester-type polyurethane prepolymer-coated leavening agent emulsion.

[0027] Preparation Example 3: The preparation of polyester polyurethane prepolymer coated leavening agent emulsion specifically includes the following processes: Weigh 4.6 parts by weight of nano-magnesium carbonate and 180 parts by weight of deionized water, mix and stir, then add 0.01 parts by weight of sodium dodecylbenzenesulfonate, and then perform ultrasonic dispersion treatment at room temperature with an ultrasonic power of 350W for 15 minutes. Weigh 100 parts by weight of the ultrasonically dispersed dispersion slurry and add it to the reactor, then take 45 parts by weight of hydroxyethyl methacrylate and 0.25 parts by weight of potassium persulfate and add them to the above reactor to mix with the dispersion slurry. At this time, nitrogen is introduced into the reactor to exhaust the air in the reactor, the reactor is closed, and the reactor is heated to 70°C and the reaction time is 4 hours. After the reaction is completed, it is naturally cooled to room temperature to obtain a polyacrylate emulsion coated with a leavening agent emulsion; 16 parts by weight of a polyacrylate emulsion-coated leavening agent emulsion was weighed and placed into a reactor and stirred at 100 rpm. Then, 9 parts by weight of hexamethylene diisocyanate, 11 parts by weight of phthalic anhydride polyester polyol HF-8056, and 0.03 parts by weight of dibutyltin dilaurate were added to the reactor and mixed with the polyacrylate emulsion-coated leavening agent emulsion. Nitrogen was then introduced into the reactor as a protective gas. The reactor was then heated to 80°C and the reaction timed for 2 hours. After the reaction was complete, the mixture was poured out while hot and allowed to cool naturally to obtain a polyester-type polyurethane prepolymer-coated leavening agent emulsion.

[0028] Preparation Example 4: The preparation of polyester polyurethane prepolymer coated leavening agent emulsion specifically includes the following processes: Weigh 5 parts by weight of nano-magnesium carbonate and 200 parts by weight of deionized water, mix and stir, then add 0.01 parts by weight of sodium dodecylbenzenesulfonate, and then perform ultrasonic dispersion treatment at room temperature with an ultrasonic power of 400W for 15 minutes. Weigh 100 parts by weight of the ultrasonically dispersed dispersion slurry and add it to the reactor, then take 50 parts by weight of hydroxyethyl methacrylate and 0.3 parts by weight of potassium persulfate and add them to the above reactor to mix with the dispersion slurry. At this time, nitrogen is introduced into the reactor to exhaust the air in the reactor, the reactor is closed, and the reactor is heated to 70°C and the reaction time is 5 hours. After the reaction is completed, it is naturally cooled to room temperature to obtain a polyacrylate emulsion coated with a leavening agent emulsion; 16 parts by weight of a polyacrylate emulsion-coated leavening agent emulsion was weighed and placed into a reactor and stirred at 100 rpm. Then, 11 parts by weight of hexamethylene diisocyanate, 12 parts by weight of phthalic anhydride polyester polyol HF-8056, and 0.03 parts by weight of dibutyltin dilaurate were added to the reactor and mixed with the polyacrylate emulsion-coated leavening agent emulsion. Nitrogen was then introduced into the reactor as a protective gas. The reactor was then heated to 80°C and the reaction timed for 2.5 hours. After the reaction was completed, the mixture was poured out while hot and allowed to cool naturally to obtain a polyester-type polyurethane prepolymer-coated leavening agent emulsion.

[0029] Preparation Example 5: The preparation of polyester polyurethane prepolymer coated leavening agent emulsion specifically includes the following processes: The nano-magnesium carbonate in Preparation Example 3 was replaced by sodium carbonate, and the deionized water was replaced by anhydrous ethanol, while the other conditions remained unchanged.

[0030] Preparation Example 6: The preparation of polyether polyurethane prepolymer coated leavening agent emulsion specifically includes the following processes: The phthalic anhydride polyester polyol HF-8056 in Preparation Example 3 was replaced with polyethylene glycol 400, and the other conditions remained unchanged.

[0031] Preparation Example 7: The preparation of polyester polyurethane prepolymer specifically includes the following processes: 11 parts by weight of hexamethylene diisocyanate, 12 parts by weight of phthalic anhydride polyester polyol HF-8056, and 0.03 parts by weight of dibutyltin dilaurate were added to a reactor and mixed and stirred. Nitrogen was then introduced into the reactor as a protective gas. The reactor was then heated to 80°C and the reaction timed for 2.5 hours. After the reaction was complete, the mixture was poured out while hot and allowed to cool naturally to obtain a polyester-type polyurethane prepolymer.

[0032] Example 1: A method for preparing a water-soluble UV inkjet ink specifically comprises the following steps: According to weight percentage, 30% of the polyester polyurethane prepolymer-coated leavening agent emulsion obtained in Preparation Example 1 and 57.7% of 1,6-hexanediol diacrylate were put into a sample bottle, and then placed in a water bath and mixed and heated to 40°C. Then, magnetic stirring was performed at a speed of 400 r / min for 20 minutes, and then 8% of water-soluble dye basic violet 10 and 0.3% of silicone leveling agent WT 4116 were added and continued to mix and stir for 20 minutes. Then, the mixture was transferred to a dark environment, and finally 4% of photoinitiator 907 was added, stirred in the dark for 30 minutes, and cooled to room temperature to obtain a water-soluble UV inkjet ink.

[0033] Example 2: A method for preparing a water-soluble UV inkjet ink specifically comprises the following steps: According to weight percentage, 34% of the polyester polyurethane prepolymer-coated leavening agent emulsion obtained in Preparation Example 2 and 50.6% of neopentyl glycol diacrylate were put into a sample bottle, and then placed in a water bath and mixed and heated to 40°C. Then, magnetic stirring was performed at a speed of 400 r / min for 25 minutes, and then 10% of water-soluble dye Acid Yellow 23, 0.3% of silicone leveling agent WT 4116 and 0.1% of polyvinyl alcohol were added and continued to mix and stir for 25 minutes, and then transferred to a dark environment. Finally, 5% of photoinitiator 1173 was added, stirred in the dark for 35 minutes, and cooled to room temperature to obtain a water-soluble UV inkjet ink.

[0034] Example 3: A method for preparing a water-soluble UV inkjet ink specifically comprises the following steps: According to weight percentage, 38% of the polyester polyurethane prepolymer-coated leavening agent emulsion obtained in Preparation Example 3 and 43.4% of dipropylene glycol diacrylate were put into a sample bottle, and then placed in a water bath and mixed and heated to 45°C. Then, magnetic stirring was carried out at a speed of 400 r / min for 25 minutes, and then 12% of water-soluble dye Acid Red 18, 0.5% of silicone leveling agent WT 4117 and 0.1% of polyvinyl alcohol were added and continued to mix and stir for 25 minutes. Then, the mixture was transferred to a dark environment, and finally 6% of photoinitiator 184 was added, stirred in the dark for 35 minutes, and cooled to room temperature to obtain a water-soluble UV inkjet ink.

[0035] Example 4: A method for preparing a water-soluble UV inkjet ink specifically comprises the following steps: According to weight percentage, 40% of the polyester polyurethane prepolymer-coated leavening agent emulsion obtained in Preparation Example 4 and 38.4% of dipropylene glycol diacrylate were put into a sample bottle, and then placed in a water bath and mixed and heated to 50°C. Then, magnetic stirring was carried out at a speed of 400 r / min for 30 minutes, and then 14% of the water-soluble dye Acid Red 18 and 0.6% of the silicone leveling agent WT 4117 were added and continued to mix and stir for 30 minutes, and then transferred to a dark environment. Finally, 7% of the photoinitiator 819 was added, stirred in the dark for 40 minutes, and cooled to room temperature to obtain a water-soluble UV inkjet ink.

[0036] Comparative Example 1: A method for preparing a water-soluble UV inkjet ink specifically comprises the following steps: The polyester polyurethane prepolymer-coated leavening agent emulsion in Example 4 was replaced by the polyester polyurethane prepolymer-coated leavening agent emulsion obtained in Preparation Example 5, and the other conditions remained the same as in Example 4.

[0037] Comparative Example 2: A method for preparing a water-soluble UV inkjet ink specifically comprises the following steps: The polyester polyurethane prepolymer-coated leavening agent emulsion in Example 4 was replaced by the polyether polyurethane prepolymer-coated leavening agent emulsion obtained in Preparation Example 6, and the other conditions remained the same as in Example 4.

[0038] Comparative Example 3: A method for preparing a water-soluble UV inkjet ink specifically comprises the following steps: According to weight percentage, 32% of the polyester polyurethane prepolymer obtained in Preparation Example 7, 8% of nano-magnesium carbonate and 38.4% of dipropylene glycol diacrylate were put into a sample bottle, and then placed in a water bath and mixed and heated to 45°C. Then, magnetic stirring was carried out at a speed of 400 r / min for 25 minutes, and then 14% of water-soluble dye Acid Red 18 and 0.6% of silicone leveling agent WT 4117 were added and continued to mix and stir for 25 minutes. Then, the mixture was transferred to a dark environment, and finally 7% of photoinitiator 184 was added, stirred in the dark for 35 minutes, and cooled to room temperature to obtain a water-soluble UV inkjet ink.

[0039] Comparative Example 4: A method for preparing a water-soluble UV inkjet ink specifically comprises the following steps: According to weight percentage, 32% of the polyester polyurethane prepolymer obtained in Preparation Example 7, 8% of nano-magnesium carbonate, 37.3% of dipropylene glycol diacrylate and 1% of polyvinyl alcohol were put into a sample bottle, and then placed in a water bath and mixed and heated to 45°C. Then, magnetic stirring was carried out at a speed of 400 r / min for 25 minutes, and then 14% of water-soluble dye Acid Red 18, 0.6% of silicone leveling agent WT 4117 and 0.1% of polyvinyl alcohol were added and continued to mix and stir for 25 minutes. Then, the mixture was transferred to a dark environment, and finally 7% of photoinitiator 184 was added, stirred in the dark for 35 minutes, and cooled to room temperature to obtain a water-soluble UV inkjet ink.

[0040] Comparative Example 5: A method for preparing a water-soluble UV inkjet ink specifically comprises the following steps: The dipropylene glycol diacrylate in Example 4 was replaced by ethoxyethoxyethyl acrylate, and the other conditions remained the same as in Example 4.

[0041] Comparative Example 6: A method for preparing a water-soluble UV inkjet ink specifically comprises the following steps: The water-soluble dye Acid Red 18 in Example 4 was replaced by Pigment Red 254, and the other conditions remained the same as in Example 4.

[0042] The viscosity of the water-soluble UV inkjet inks prepared in Examples 1 to 4 and Comparative Examples 1 to 6 was measured using a rotational viscometer at a temperature of 25±1°C. The torque percentage reading was controlled within a range of 10% to 90% and the measurement was started. The results are shown in Table 1 below.

[0043] Table 1 Viscosity test

[0044] The water-soluble UV inkjet inks prepared in Examples 1-4 and Comparative Examples 1-6 were evenly coated on the surface of an acrylic sheet. The sheet was then placed on the conveyor belt of a UV curing machine and cured under light. After irradiation, the cured water-soluble UV inkjet ink was considered completely dry, with the surface dry and non-sticky. The minimum time required for the water-soluble UV inkjet ink to completely dry was recorded. The results are shown in Table 2 below.

[0045] Table 2 Curing time test

[0046] After the drying test, the acrylic sheet was placed in a hot acetic acid solution with a molar concentration of 0.01 mol / L and a temperature of 70±5°C and soaked for 5 minutes. The ink on the surface of the acrylic sheet was observed to see if any swelling or protrusions appeared. The acetic acid solution on the surface was then removed and rinsed with water until the pH of the rinse water was neutral. Wearing gloves, the swollen and protruding ink material was gently rubbed, and then rinsed with water again. Finally, it was recorded whether the ink on the surface of the acrylic sheet was completely detached and cleaned. The results are shown in Table 3 below.

[0047] Table 3 Flushing removal test

[0048] The water-soluble UV inkjet inks prepared in Examples 1 to 4 and Comparative Examples 1 to 6 were respectively loaded into ink cartridges of desktop printers, and the printing clarity and printing smoothness were tested. The results are shown in Table 4 below.

[0049] Table 4 Print test

[0050] The following conclusions can be drawn from the test results in Tables 1 to 4 above: (1) It can be found from Examples 1 to 4 that the present invention forms a polyacrylate emulsion-coated leavening agent emulsion by coating an inorganic chemical leavening agent through emulsion polymerization, and then polymerizes it with diisocyanate and polyester polyol to form a polyester polyurethane prepolymer-coated leavening agent emulsion, and finally mixes and stirs it with an acrylate monomer, a photoinitiator, a water-soluble dye and an organosilicon leveling agent to form a water-soluble UV inkjet ink, which has good viscosity performance, a short curing time, is easy to rinse and remove, and has a good printing effect.

[0051] (2) Comparative Example 1 shows that the viscosity and cleaning effect of the ink are good, and the curing time is slightly worse. However, during the actual printing image test, the nozzle is severely clogged, the ink drips, and the printing cannot be completed. This may be because the particle size of the sodium carbonate is too large, causing the nozzle to be clogged and the ink output to be poor.

[0052] (3) Comparative Example 2 shows that the viscosity and printing effect of the ink are good, and the curing time is slightly worse. However, when the flushing test is performed again, it is found that the ink surface does not swell or fall off, and the ink cannot be removed. This may be due to the ether bond structure contained in the polyether polyurethane prepolymer constructed by polyethylene glycol 400. This structure is relatively stable and is not easily hydrolyzed and broken under acidic conditions. Therefore, acetic acid is difficult to penetrate, resulting in difficulty in effective contact with the inorganic chemical leavening agent, making it difficult to flush.

[0053] (4) Comparative Example 3 shows that the viscosity and curing time of the ink are good, but when flushing, it is found that only part of the expanded protrusions on the ink surface fall off, and there is a lot of ink residue, and the printing effect is poor. The reason for this may be that the nano-magnesium carbonate has not been coated and is prone to agglomeration and uneven dispersion when added directly, resulting in poor flushing effect. The agglomeration makes the nano-calcium carbonate particles aggregate larger, which may further affect the printing effect.

[0054] (5) Comparative Example 4 shows that the ink has a good flushing effect, but the viscosity increases further, the curing time becomes longer, and the printing effect is poor. This may be because although the polyvinyl alcohol dispersant has good dispersing properties, it has a high viscosity. When mixed with this system, the overall viscosity of the ink may increase. The increased viscosity leads to uneven ink discharge and poor printing effect.

[0055] (6) Comparative Example 5 shows that although the viscosity, cleaning effect and printing effect of the ink are good, the curing time is long. This may be because ethoxyethoxyethyl acrylate contains only a single olefin structure compared to dipropylene glycol diacrylate and is a monofunctional monomer. After polymerization, the monofunctional monomer mainly exhibits linear polymer properties. Although the viscosity is low, the curing time caused by ultraviolet light irradiation is prolonged, which is not conducive to practical use.

[0056] (7) Comparative Example 6 shows that the viscosity and printing effect of the ink are good, the curing time is slightly worse, but there is still ink residue after flushing. This may be because Pigment Red 254 is a water-insoluble dye. Although acetic acid soaking can make the resin in the ink swell and bulge and peel off the acrylic plate, part of the water-insoluble dye Pigment Red 254 is still solidified on the surface of the acrylic plate, making it impossible to be completely dissolved and rinsed away by water.

[0057] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A water-soluble UV inkjet ink, characterized in that: The water-soluble UV inkjet ink comprises the following raw materials in weight percentage: 30%~40% polyester polyurethane prepolymer coated leavening agent emulsion, 38.4%~57.7% acrylate monomer, 4%~7% photoinitiator, 8%~14% water-soluble dye, 0.3%~0.6% silicone leveling agent and 0~0.1% surfactant.

2. The water-soluble UV inkjet ink according to claim 1, characterized in that: The preparation method of the polyester polyurethane prepolymer coated leavening agent emulsion comprises the following steps: An emulsifier, an inorganic chemical leavening agent and deionized water are mixed in a weight ratio of 0.01:4-5:150-200 and then ultrasonically dispersed to form a dispersed slurry; The dispersed slurry, hydroxyl acrylate monomer and potassium persulfate are mixed in a weight ratio of 100:30-50:0.13-0.3, heated to 65° C.-70° C. and reacted for 3 h-5 h to obtain a polyacrylate emulsion-coated leavening agent emulsion; The polyacrylate emulsion-coated leavening agent emulsion, diisocyanate, polyester polyol and dibutyltin dilaurate are mixed in a weight ratio of 15-16:7-11:10-12:0.02-0.03, heated to 75° C.-80° C. and reacted for 1.5 h-2.5 h to obtain the polyester polyurethane prepolymer-coated leavening agent emulsion.

3. The water-soluble UV inkjet ink according to claim 2, characterized in that: The inorganic chemical leavening agent includes nano calcium carbonate or nano magnesium carbonate.

4. The water-soluble UV inkjet ink according to claim 2, characterized in that: The hydroxy acrylate monomer includes hydroxypropyl acrylate or hydroxyethyl methacrylate.

5. The water-soluble UV inkjet ink according to claim 2, characterized in that: The diisocyanate includes isophorone diisocyanate or hexamethylene diisocyanate.

6. The water-soluble UV inkjet ink according to claim 2, characterized in that: The polyester polyol includes phthalic anhydride polyester polyol HF-8031 or phthalic anhydride polyester polyol HF-8056.

7. The water-soluble UV inkjet ink according to claim 1, characterized in that: The acrylate monomer includes 1,6-hexanediol diacrylate, neopentyl glycol diacrylate or dipropylene glycol diacrylate.

8. The water-soluble UV inkjet ink according to claim 1, characterized in that: The water-soluble dye includes Basic Violet 10, Acid Yellow 23 or Acid Red 18.

9. The water-soluble UV inkjet ink according to claim 1, characterized in that: The organosilicon leveling agent includes leveling agent WT 4116 or leveling agent WT 4117.

10. A method for preparing a water-soluble UV inkjet ink according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: The polyester polyurethane prepolymer coated leavening agent emulsion and the acrylate monomer are mixed, heated to 40° C. to 50° C. and stirred for 20 min to 30 min, then the water-soluble dye, silicone leveling agent and surfactant are added and stirred for 20 min to 30 min, and finally the photoinitiator is added and stirred in a light-proof environment for 30 min to 40 min to obtain the water-soluble UV inkjet ink.

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