A water-soluble UV ink and its preparation method

Abstract

This invention belongs to the field of UV ink technology, specifically relating to a water-soluble UV ink and its preparation method. By weight, the water-soluble UV ink comprises the following raw materials: 65-70 parts of waterborne polyurethane acrylate, 5.6-6.8 parts of photosensitive monomer, 3.7-4.5 parts of pigment, 3.5-4.5 parts of dispersant, 3-5 parts of photoinitiator, 1-2 parts of modified polyvinyl alcohol, 0.5-1 part of photoactivator, 0.5-1 part of surfactant, and 65-70 parts of deionized water. This ink exhibits excellent properties such as fast curing speed, strong adhesion, high hardness, good wash fastness, and clear printed patterns.

Description

Technical Field

[0001] This invention belongs to the field of UV ink technology, specifically relating to a water-soluble UV ink and its preparation method. Background Technology

[0002] Water-based UV inkjet inks are mainly composed of water-based resins, photoinitiators, colorants, and other additives. The water-based resins should contain unsaturated functional groups with high photocuring activity to ensure rapid UV curing and faster drying. Currently, commonly used water-based resins for preparing UV inks include acrylates and their modified forms. Under the influence of an electric field, inkjet inks are ejected from the nozzles of an inkjet printer onto the substrate to form images. Therefore, water-based UV inks need to possess good stability, non-clogging nozzles, good moisture retention, non-corrosive printhead properties, and resistance to fading.

[0003] Water-based UV ink uses water and environmentally friendly solvents as diluents, employs UV irradiation curing technology, and uses water-based UV-curable resin as a prepolymer. A photoinitiator initiates the polymerization and film formation of the prepolymer. This ink combines the advantages of UV inks and water-based inks, retaining the rapid drying characteristics of UV inks while also offering advantages such as environmental friendliness and high efficiency.

[0004] Polyvinyl alcohol (PVA0588) has a low degree of polymerization, which can improve the viscosity of waterborne polyurethane acrylate, but its poor water resistance will affect the adhesion, hardness and other properties of the ink film, thus limiting the application of PVA0588 in waterborne UV inkjet inks. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, one of the objectives of this invention is to provide a water-soluble UV ink that has excellent properties such as fast curing speed, strong adhesion, high hardness, good wash fastness, and clear printed patterns.

[0006] The second objective of this invention is to provide a method for preparing water-soluble UV ink, which is simple in process, easy to operate, and suitable for industrial production.

[0007] The objective of this invention is achieved through the following technical solution: A water-soluble UV ink, by weight, comprises the following raw materials: 65-70 parts of waterborne polyurethane acrylate, 5.6-6.8 parts of photosensitive monomer, 3.7-4.5 parts of pigment, 3.5-4.5 parts of dispersant, 3-5 parts of photoinitiator, 1-2 parts of modified polyvinyl alcohol, 0.5-1 part of photoactivator, 0.5-1 part of surfactant, and 65-70 parts of deionized water; The structure of the photosensitive monomer is as follows: .

[0008] Preferably, the method for preparing the photosensitive monomer includes the following steps: (1) Under inert gas protection, thionyl chloride was added to anhydrous ethanol, followed by pyrrolidine-3-carboxylic acid. The mixture was stirred at 30-40°C for 8-12 h and concentrated to obtain residue 1. Dichloromethane, triethylamine and acryloyl chloride were added to residue 1 and stirred at 40-50°C for 5-8 h. The mixture was concentrated to obtain residue 2. Anhydrous ethanol and sodium hydroxide solution were added to residue 2 and the mixture was stirred for 1-3 h and then purified to obtain intermediate 1. The structural formula of intermediate 1 is: ; (2) The intermediate 1, Wilsmeer reagent and triethylamine were added to dichloromethane, and then hydrazine hydrate was added. After stirring, the mixture was purified to obtain intermediate 2. The structural formula of intermediate 2 is as follows: ; (3) Add the intermediate 2 to anhydrous ethanol, then add sodium hydroxide and carbon disulfide, stir, filter, and dry the filter cake; add concentrated sulfuric acid to the filter cake in portions, continue stirring, adjust the pH, and purify by distillation to obtain the photosensitive monomer.

[0009] In this invention, intermediate 1 is prepared by reacting the secondary amine of pyrrolidine-3-carboxylic acid with acryloyl chloride; intermediate 2 is prepared by reacting the carboxyl group of intermediate 1 with hydrazine hydrate; and photosensitive monomer is prepared by reacting the primary amine of intermediate 2 with carbon disulfide.

[0010] Preferably, the molar ratio of pyrrolidine-3-carboxylic acid, thionyl chloride, triethylamine, acryloyl chloride, and sodium hydroxide in step (1) is 1:(2-2.5):(2.5-3):(1-1.2):(3.5-4.5); and the concentration of the sodium hydroxide solution is 4 mol / L.

[0011] Preferably, in step (2), the molar ratio of intermediate 1, Wilsmeer reagent, triethylamine, and hydrazine hydrate is 1:(1-1.2):(3-4):(4-4.5); and the stirring time is 5-8 hours.

[0012] Preferably, in step (3), the molar ratio of intermediate 2, sodium hydroxide, carbon disulfide, and H2SO in concentrated sulfuric acid is 1:(2-2.5):(2.5-3):(4.5-5); the temperature at which intermediate 2 is added is -5 to -10°C; the stirring temperature is 5-10°C and the stirring time is 3-5 h; the mass fraction of concentrated sulfuric acid is 98 wt%; and the stirring time is 3-5 h.

[0013] Preferably, the modified polyvinyl alcohol is prepared as follows: Polyvinyl alcohol, arecoline, and concentrated hydrochloric acid were added to water, and after the reaction, the pH was adjusted, dialyzed, and dried to obtain the modified polyvinyl alcohol.

[0014] This invention utilizes concentrated hydrochloric acid to catalyze the esterification reaction between the hydroxyl groups of polyvinyl alcohol and the carboxyl groups of arecoline, thereby obtaining modified polyvinyl alcohol.

[0015] Preferably, the molar ratio of polyvinyl alcohol, areca catechin, and HCl in concentrated hydrochloric acid is 1:(0.3-0.5):(0.3-0.5); the mass fraction of concentrated hydrochloric acid is 37wt%; the reaction temperature is 80-100℃ and the reaction time is 5-8h; the pH is adjusted to 9-9.5; the dialysis time is 24-48h; and the polyvinyl alcohol is PVA 0588.

[0016] Preferably, the pigment is carbon black; the dispersant is composed of dispersant 760 and dispersant 750 in a mass ratio of 1:(1-4); the photoinitiator is composed of initiator 819 and TPO in a mass ratio of 1:1; the photoactivator is triethanolamine; and the surfactant is surfactant 104.

[0017] The preparation method of the above-mentioned water-soluble UV ink includes the following steps: S1. Add pigment, dispersant, and photosensitive monomer to 1 / 7-2 / 7 of deionized water, let stand, and then grind to obtain color paste; S2. Add waterborne polyurethane acrylate and modified polyvinyl alcohol to the remaining deionized water, stir evenly, then add photoactivator and surfactant, continue stirring evenly, then add the color paste, stir evenly, then add photoinitiator, stir for 25-35 minutes to obtain the final product.

[0018] Preferably, the settling time in step S1 is 10-16 hours, and the grinding time is 6-7 hours.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention provides a water-soluble UV ink, the raw materials of which include water-based polyurethane acrylate, photosensitive monomer, pigment, dispersant, photoinitiator, modified polyvinyl alcohol, photoactivator, surfactant, and deionized water. This ink has excellent properties such as fast curing speed, strong adhesion, high hardness, good wash fastness, and clear printed patterns.

[0020] (2) This invention improves the curing speed and adhesion of UV inks by adding photosensitive monomers with specific structures. The acryloyl groups at the ends of the photosensitive monomer molecules of this invention undergo free radical polymerization under the action of photoinitiators, and react synergistically with the acrylate end groups of waterborne polyurethane acrylates to form a cross-linking network, thereby improving the curing speed; its pyrrolidine ring and 1,3,4-thiadiazole ring endow the molecule with high polarity, improves the compatibility with the waterborne system, improves the dispersion stability of pigments and resins in the aqueous phase, prevents pigment agglomeration, and improves water solubility; at the same time, the thiol groups on the thiadiazole ring can form MS covalent bonds or coordination bonds with the surface of the metal substrate, thereby significantly improving the adhesion.

[0021] (3) This invention improves the hardness, wash fastness, and print pattern clarity of UV ink by adding modified polyvinyl alcohol prepared by a specific modification method. The modified polyvinyl alcohol of this invention retains some hydroxyl groups to maintain water solubility, while the arecoside groups introduced by esterification increase steric hindrance; its low viscosity characteristics can reduce the overall viscosity of the ink to ensure inkjet flowability, and improve the pigment dispersion stability and prevent pigment agglomeration through steric hindrance, thereby improving the pattern clarity and integrity, while also improving the hardness and wash fastness of the cured film.

[0022] (4) The present invention also provides a method for preparing water-soluble UV ink, which is simple in process, easy to operate and suitable for industrial production. Attached Figure Description

[0023] Figure 1 The infrared spectrum of the modified polyvinyl alcohol in Example 4 is shown below; curve a is the infrared spectrum of polyvinyl alcohol, and curve b is the infrared spectrum of the modified polyvinyl alcohol. Detailed Implementation

[0024] The present invention will be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments are based on conventional conditions or product instructions. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0025] In this embodiment of the invention, the pigment is carbon black; the dispersant is composed of dispersant 760 and dispersant 750 in a mass ratio of 1:2; the photoinitiator is composed of initiator 819 and TPO in a mass ratio of 1:1; the photoactivator is triethanolamine; and the surfactant is surfactant 104.

[0026] Preparation Example 1 The preparation steps of the photosensitive monomer are as follows: ; (1) Under nitrogen protection at 0℃, thionyl chloride (22 mmol) was added to 50 mL of anhydrous ethanol, stirred until homogeneous, and then pyrrolidine-3-carboxylic acid (10 mmol) was added. The mixture was stirred at 35℃ for 10 h. After concentration, residue 1 was obtained. 50 mL of dichloromethane, triethylamine (28 mmol) and acryloyl chloride (11 mmol) were added to residue 1, and the mixture was stirred at 45℃ for 6 h. After concentration, residue 2 was obtained. 50 mL of anhydrous ethanol and 4 mol / L sodium hydroxide solution (40 mmol) were added to residue 2, and the mixture was stirred at room temperature for 2 h. The reaction solution was concentrated, and water and ethyl acetate were added until the layers were distinct. After separation, the pH of the aqueous phase was adjusted to 2 with 4 mol / L hydrochloric acid solution. The mixture was extracted with n-butanol, the organic phase was washed with saturated sodium chloride, dried with sodium sulfate, and finally purified by column chromatography (V 二氯甲烷 V 甲醇 =6:1), intermediate 1 was prepared; the NMR and mass spectrometry results of intermediate 1 are as follows: 1 HNMR (C8H) 11 NO3,400MHz,DMSO-d6)δ10.83(s,1H),6.62(q,1H),6.02(dd,1H),5.58(dd,1H), 3.82-3.41(m,4H),2.66-2.64(m,1H),2.15-1.92(m,2H);LC-MSm / z:170.07[M+H] + .

[0027] (2) Intermediate 1 (10 mmol), Wilsmeier reagent (CAS: 149409-22-3, 11 mmol), and triethylamine (34 mmol) were dissolved in 60 mL of dichloromethane, and then hydrazine hydrate (42 mmol) was added. The mixture was stirred for 7 h, and the mixture was washed successively with saturated sodium bicarbonate solution and water. The organic layer was dried with sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude residue was purified by recrystallization from 95% ethanol to obtain intermediate 2. The NMR and mass spectrometry results of intermediate 2 are as follows: 1 HNMR (C8H) 13 N3O2,400MHz,DMSO-d6)δ9.03(s,1H),6.62(q,1H),6.02(dd,1H),5.58(dd,1H),4.50(s ,2H),3.82-3.41(m,4H),2.74-2.72(m,1H),2.15-1.92(m,2H);LC-MSm / z:184.10[M+H] + .

[0028] (3) At -8°C, intermediate 2 (10 mmol) was added to 10 mL of anhydrous ethanol, stirred until homogeneous, and then sodium hydroxide (22 mmol) and carbon disulfide (27 mmol) were added. The mixture was stirred at 8°C for 4 h, the reaction solution was filtered, and the filter cake was dried. Concentrated sulfuric acid (98 wt%, 47 mmol) was added to the filter cake in three portions, and the mixture was stirred at 8°C for 4 h. The pH of the system was adjusted to neutral with sodium ethoxide, and the mixed phase was purified by distillation to obtain the photosensitive monomer. The NMR and mass spectrometry results of the photosensitive monomer were as follows: 1 HNMR (C9H) 11 N3OS2,400MHz,DMSO-d6)δ13.00(s,1H),6.62(q,1H),6.02(dd,1H),5.58(dd,1H) ,3.89-3.41(m,4H),3.09-3.07(m,1H),2.22-1.96(m,2H);LC-MSm / z:242.03[M+H] + .

[0029] Preparation Example 2 The preparation steps of the photosensitive monomer are as follows: (1) Under nitrogen protection at 0℃, thionyl chloride (20 mmol) was added to 50 mL of anhydrous ethanol, stirred until homogeneous, and then pyrrolidine-3-carboxylic acid (10 mmol) was added. The mixture was stirred at 30℃ for 12 h. After concentration, residue 1 was obtained. 50 mL of dichloromethane, triethylamine (25 mmol) and acryloyl chloride (10 mmol) were added to residue 1, and the mixture was stirred at 40℃ for 8 h. After concentration, residue 2 was obtained. 50 mL of anhydrous ethanol and 4 mol / L sodium hydroxide solution (35 mmol) were added to residue 2, and the mixture was stirred at room temperature for 1 h. The reaction solution was concentrated, and water and ethyl acetate were added until the layers were distinct. After separation, the pH of the aqueous phase was adjusted to 2 with 4 mol / L hydrochloric acid solution. The mixture was extracted with n-butanol, the organic phase was washed with saturated sodium chloride, dried with sodium sulfate, and finally purified by column chromatography (V 二氯甲烷 V 甲醇 =6:1), intermediate 1 was prepared; the NMR and mass spectrometry results of intermediate 1 were consistent with those of preparation example 1.

[0030] (2) Intermediate 1 (10 mmol), Wilsmeier reagent (10 mmol) and triethylamine (30 mmol) were dissolved in 60 mL of dichloromethane, and then hydrazine hydrate (40 mmol) was added. The mixture was stirred for 5 h. The mixture was washed successively with saturated sodium bicarbonate solution and water. The organic layer was dried with sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude residue was purified by recrystallization from 95% ethanol to obtain intermediate 2. The NMR and mass spectrometry results of intermediate 2 were consistent with those of preparation example 1.

[0031] (3) At -10°C, the intermediate 2 (10 mmol) was added to 10 mL of anhydrous ethanol and stirred until homogeneous. Then, sodium hydroxide (20 mmol) and carbon disulfide (25 mmol) were added and stirred at 5°C for 5 h. The reaction solution was filtered and the filter cake was dried. Concentrated sulfuric acid (98 wt%, 45 mmol) was added to the filter cake in three portions and stirred at 5°C for 5 h. The pH of the system was adjusted to neutral with sodium ethoxide and the mixed phase was purified by distillation to obtain the photosensitive monomer. The NMR and mass spectrometry results of the photosensitive monomer were consistent with those of Preparation Example 1.

[0032] Preparation Example 3 The preparation steps of the photosensitive monomer are as follows: (1) Under nitrogen protection at 0℃, thionyl chloride (25 mmol) was added to 50 mL of anhydrous ethanol, stirred until homogeneous, and then pyrrolidine-3-carboxylic acid (10 mmol) was added. The mixture was stirred at 40℃ for 8 h. After concentration, residue 1 was obtained. 50 mL of dichloromethane, triethylamine (30 mmol) and acryloyl chloride (12 mmol) were added to residue 1, and the mixture was stirred at 50℃ for 5 h. After concentration, residue 2 was obtained. 50 mL of anhydrous ethanol and 4 mol / L sodium hydroxide solution (45 mmol) were added to residue 2, and the mixture was stirred at room temperature for 3 h. The reaction solution was concentrated, and water and ethyl acetate were added until the layers were distinct. After separation, the pH of the aqueous phase was adjusted to 2 with 4 mol / L hydrochloric acid solution. The mixture was extracted with n-butanol, the organic phase was washed with saturated sodium chloride, dried with sodium sulfate, and finally purified by column chromatography (V 二氯甲烷 V 甲醇 =6:1), intermediate 1 was prepared; the NMR and mass spectrometry results of intermediate 1 were consistent with those of preparation example 1.

[0033] (2) Intermediate 1 (10 mmol), Wilsmeier reagent (12 mmol) and triethylamine (40 mmol) were dissolved in 60 mL of dichloromethane, and then hydrazine hydrate (45 mmol) was added. The mixture was stirred for 8 h. The mixture was washed successively with saturated sodium bicarbonate solution and water. The organic layer was dried with sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude residue was purified by recrystallization from 95% ethanol to obtain intermediate 2. The NMR and mass spectrometry results of intermediate 2 were consistent with those of preparation example 1.

[0034] (3) At -5°C, the intermediate 2 (10 mmol) was added to 10 mL of anhydrous ethanol and stirred until homogeneous. Then, sodium hydroxide (25 mmol) and carbon disulfide (30 mmol) were added and stirred at 10°C for 3 h. The reaction solution was filtered and the filter cake was dried. Concentrated sulfuric acid (98 wt%, 50 mmol) was added to the filter cake in three portions and stirred at 10°C for 3 h. The pH of the system was adjusted to neutral with sodium ethoxide and the mixed phase was purified by distillation to obtain the photosensitive monomer. The NMR and mass spectrometry results of the photosensitive monomer were consistent with those of Preparation Example 1.

[0035] Preparation Example 4 The preparation steps of modified polyvinyl alcohol are as follows: Polyvinyl alcohol (PVA 0588, 10 mmol), arecoline (4 mmol), and concentrated hydrochloric acid (4 mmol, 37 wt%) were added to 50 mL of water and reacted at 90 °C for 7 h. The pH of the system was adjusted to 9.2, and then dialyzed in deionized water for 36 h. After drying, the modified polyvinyl alcohol was obtained.

[0036] Preparation Example 5 The preparation steps of modified polyvinyl alcohol are as follows: Polyvinyl alcohol (PVA 0588, 10 mmol), arecaine (3 mmol), and concentrated hydrochloric acid (3 mmol, 37 wt%) were added to 50 mL of water and reacted at 80 °C for 8 h. The pH of the system was adjusted to 9, and then dialyzed in deionized water for 24 h. After drying, the modified polyvinyl alcohol was obtained.

[0037] Preparation Example 6 The preparation steps of modified polyvinyl alcohol are as follows: Polyvinyl alcohol (PVA 0588, 10 mmol), arecaine (5 mmol), and concentrated hydrochloric acid (5 mmol, 37 wt%) were added to 50 mL of water and reacted at 100 °C for 5 h. The pH of the system was adjusted to 9.5, and then dialyzed in deionized water for 48 h. After drying, the modified polyvinyl alcohol was obtained.

[0038] Example 1 A water-soluble UV ink, by weight, comprises the following raw materials: 68 parts of waterborne polyurethane acrylate, 1.5 parts of modified polyvinyl alcohol of Preparation Example 4, 4.2 parts of pigment, 4 parts of dispersant, 6.5 parts of photosensitive monomer of Preparation Example 1, 4 parts of photoinitiator, 0.7 parts of photoactivator, 0.9 parts of surfactant, and 68 parts of deionized water.

[0039] The preparation method of the above-mentioned water-soluble UV ink includes the following steps: S1. Add pigment, dispersant, and photosensitive monomer to 1 / 6 of deionized water, let stand for 14 hours, add zirconia beads (the mass ratio of zirconia beads to grinding material is 3:1, and the grinding speed is 2500 rpm) and grind for 6.5 hours to obtain color paste; S2. Add waterborne polyurethane acrylate and modified polyvinyl alcohol to the remaining deionized water and stir until homogeneous. Then add photoactivator and surfactant and continue stirring until homogeneous. Then add the above color paste and stir until homogeneous. Finally add photoinitiator and stir at room temperature for 30 minutes to obtain the final product.

[0040] Example 2 A water-soluble UV ink, by weight, comprises the following raw materials: 65 parts of waterborne polyurethane acrylate, 1 part of modified polyvinyl alcohol of Preparation Example 5, 3.7 parts of pigment, 3.5 parts of dispersant, 5.6 parts of photosensitive monomer of Preparation Example 2, 3 parts of photoinitiator, 0.5 parts of photoactivator, 0.5 parts of surfactant, and 65 parts of deionized water.

[0041] The preparation method of the above-mentioned water-soluble UV ink includes the following steps: S1. Add pigment, dispersant, and photosensitive monomer to 1 / 7 of deionized water, let stand for 10 hours, add zirconia beads (the mass ratio of zirconia beads to grinding material is 3:1, and the grinding speed is 2500 rpm) and grind for 6 hours to obtain color paste; S2. Add waterborne polyurethane acrylate and modified polyvinyl alcohol to the remaining deionized water and stir until homogeneous. Then add photoactivator and surfactant and continue stirring until homogeneous. Then add the above color paste and stir until homogeneous. Finally add photoinitiator and stir at room temperature for 25 minutes to obtain the final product.

[0042] Example 3 A water-soluble UV ink, by weight, comprises the following raw materials: 70 parts of waterborne polyurethane acrylate, 2 parts of modified polyvinyl alcohol of Preparation Example 6, 4.5 parts of pigment, 4.5 parts of dispersant, 6.8 parts of photosensitive monomer of Preparation Example 3, 5 parts of photoinitiator, 1 part of photoactivator, 1 part of surfactant, and 70 parts of deionized water.

[0043] The preparation method of the above-mentioned water-soluble UV ink includes the following steps: S1. Add pigment, dispersant, and photosensitive monomer to 2 / 7 of deionized water, let stand for 16 hours, add zirconia beads (the mass ratio of zirconia beads to grinding material is 3:1, and the grinding speed is 2500 rpm) and grind for 7 hours to obtain color paste; S2. Add waterborne polyurethane acrylate and modified polyvinyl alcohol to the remaining deionized water and stir evenly. Then add photoactivator and surfactant and continue stirring evenly. Then add the above color paste and stir evenly. Finally add photoinitiator and stir at room temperature for 35 minutes to obtain the final product.

[0044] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the photosensitive monomer in Preparation Example 1 was replaced with acrylomorpholine.

[0045] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the modified polyvinyl alcohol in Preparation Example 4 was replaced with PVA 0588.

[0046] Experimental Example 1 Infrared spectroscopy analysis was performed on the modified polyvinyl alcohol prepared in Example 4. The results are shown in [reference needed]. Figure 1 .

[0047] Figure 1 This is the infrared spectrum of the modified polyvinyl alcohol prepared in Example 4. Curve a is the infrared spectrum of polyvinyl alcohol, and curve b is the infrared spectrum of the modified polyvinyl alcohol. Compared to curve a, curve b has a larger infrared spectrum in the 3200-3600 cm⁻¹ range. -1 The stretching absorption strength of the hydroxyl groups decreased significantly, indicating that the hydroxyl groups of polyvinyl alcohol underwent an esterification reaction with the carboxyl groups of areca catechin; at 1600-1650 cm⁻¹ -1 The peak shape changed significantly, which is consistent with the characteristic peaks of arecoline pyridine ring C=N, ring C=C skeletal vibration, and newly formed ester bond C=O; in the 1400-1500 cm⁻¹ range... -1 New multiple absorption peaks were observed for the CN and CH rings of the pyridine ring. These spectroscopic changes confirm that arecoline was successfully grafted onto the polyvinyl alcohol molecular chain via esterification.

[0048] Experimental Example 2 Adhesion performance: Tested according to GB / T 9286-2021 standard using the cross-cut test method; Hardness: Tested according to GB / T 6739-2022 standard, using the 9B-9H hardness gradient; Wash fastness: Tested according to GB / T 3921-2008 standard. A 4cm × 10cm piece of dyed fabric is placed in a steel can with a liquor ratio of 1:50. The soap solution contains 5g / L soap flakes and 2g / L sodium carbonate. The mixture is then rotated at 60℃ for 30 minutes. After washing and drying, the fabric is graded using a standard gray scale, ranging from 1 to 5, with 5 being the best. Curing speed: Apply water-based UV ink to kraft paper with a thickness of 15μm, place it in a 100W UV curing lamp box and irradiate it. Rub the cured surface with blank white paper until there is no ink residue, and record the shortest time required. The experimental results are shown in Table 1.

[0049] Table 1

[0050] The experimental results in Table 1 show that the water-soluble UV ink prepared by this invention exhibits excellent performance in terms of adhesion, hardness, curing speed, wash fastness, and print pattern clarity. In Comparative Example 1, replacing the photosensitive monomer with acryloylmorpholine resulted in decreased adhesion and prolonged curing speed, indicating that the photosensitive monomer of this invention significantly enhances adhesion and curing rate through the thiadiazole ring and acryloyl group. In Comparative Example 2, replacing modified polyvinyl alcohol with PVA resulted in decreased hardness and wash fastness, and the printed pattern became unclear and unevenly colored, indicating that the arecoline group introduced into the modified polyvinyl alcohol effectively improves pigment dispersion stability, ink flowability, and film wash resistance through steric hindrance.

[0051] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A water-soluble UV ink, characterized in that, By weight, it includes the following raw materials: 65-70 parts of waterborne polyurethane acrylate, 5.6-6.8 parts of photosensitive monomer, 3.7-4.5 parts of pigment, 3.5-4.5 parts of dispersant, 3-5 parts of photoinitiator, 1-2 parts of modified polyvinyl alcohol, 0.5-1 part of photoactivator, 0.5-1 part of surfactant, and 65-70 parts of deionized water; The structure of the photosensitive monomer is as follows: 。 2. The water-soluble UV ink according to claim 1, characterized in that, The method for preparing the photosensitive monomer includes the following steps: (1) Under inert gas protection, thionyl chloride was added to anhydrous ethanol, followed by pyrrolidine-3-carboxylic acid. The mixture was stirred at 30-40°C for 8-12 h and concentrated to obtain residue 1. Dichloromethane, triethylamine and acryloyl chloride were added to residue 1 and stirred at 40-50°C for 5-8 h. The mixture was concentrated to obtain residue 2. Anhydrous ethanol and sodium hydroxide solution were added to residue 2 and the mixture was stirred for 1-3 h and then purified to obtain intermediate 1. The structural formula of intermediate 1 is: ； (2) The intermediate 1, Wilsmeer reagent and triethylamine were added to dichloromethane, and then hydrazine hydrate was added. After stirring, the mixture was purified to obtain intermediate 2. The structural formula of intermediate 2 is as follows: ； (3) Add the intermediate 2 to anhydrous ethanol, then add sodium hydroxide and carbon disulfide, stir, filter, and dry the filter cake; add concentrated sulfuric acid to the filter cake in portions, continue stirring, adjust the pH, and purify by distillation to obtain the photosensitive monomer.

3. The water-soluble UV ink according to claim 2, characterized in that, The molar ratio of pyrrolidine-3-carboxylic acid, thionyl chloride, triethylamine, acryloyl chloride, and sodium hydroxide in step (1) is 1:(2-2.5):(2.5-3):(1-1.2):(3.5-4.5); the concentration of the sodium hydroxide solution is 4 mol / L.

4. The water-soluble UV ink according to claim 2, characterized in that, In step (2), the molar ratio of intermediate 1, Wilsmeer reagent, triethylamine, and hydrazine hydrate is 1:(1-1.2):(3-4):(4-4.5); the stirring time is 5-8h.

5. The water-soluble UV ink according to claim 2, characterized in that, In step (3), the molar ratio of intermediate 2, sodium hydroxide, carbon disulfide, and H2SO4 in concentrated sulfuric acid is 1:(2-2.5):(2.5-3):(4.5-5); the temperature at which intermediate 2 is added is -5 to -10°C; the stirring temperature is 5-10°C and the stirring time is 3-5 h; the mass fraction of concentrated sulfuric acid is 98 wt%; and the stirring time is 3-5 h.

6. The water-soluble UV ink according to claim 1, characterized in that, The modified polyvinyl alcohol is prepared as follows: Polyvinyl alcohol, arecoline, and concentrated hydrochloric acid were added to water, and after the reaction, the pH was adjusted, dialyzed, and dried to obtain the modified polyvinyl alcohol.

7. The water-soluble UV ink according to claim 6, characterized in that, The molar ratio of polyvinyl alcohol, areca catechin, and concentrated hydrochloric acid HCl is 1:(0.3-0.5):(0.3-0.5); the mass fraction of the concentrated hydrochloric acid is 37wt%; the reaction temperature is 80-100℃ and the reaction time is 5-8h; the pH is adjusted to 9-9.5; the dialysis time is 24-48h; and the polyvinyl alcohol is PVA 0588.

8. The water-soluble UV ink according to claim 1, characterized in that, The pigment is carbon black; the dispersant is composed of dispersant 760 and dispersant 750 in a mass ratio of 1:(1-4); the photoinitiator is composed of initiator 819 and TPO in a mass ratio of 1:1; the photoactivator is triethanolamine; and the surfactant is surfactant 104.

9. A method for preparing the water-soluble UV ink according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Add pigment, dispersant, and photosensitive monomer to 1 / 7-2 / 7 of deionized water, let stand, and then grind to obtain color paste; S2. Add waterborne polyurethane acrylate and modified polyvinyl alcohol to the remaining deionized water, stir evenly, then add photoactivator and surfactant, continue stirring evenly, then add the color paste, stir evenly, then add photoinitiator, stir for 25-35 minutes to obtain the final product.

10. The method for preparing the water-soluble UV ink according to claim 9, characterized in that, The settling time in step S1 is 10-16 hours, and the grinding time is 6-7 hours.

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