High-stability UV printing ink and preparation method thereof

Abstract

The invention discloses high-stability UV printing ink and a preparation method thereof, and relates to the technical field of printing ink, the printing ink comprises the following components by weight: 40-60 parts of an acrylate oligomer, 20-30 parts of an active diluent monomer, 5-10 parts of a photoinitiator, 10-15 parts of a pigment, 1-3 parts of a dispersant, 3-8 parts of a stimuli-responsive viscosity modifier, and 0.5-2 parts of an auxiliary agent; the stimuli-responsive viscosity regulator endows the ink with dynamic viscosity regulation capability, and ensures stable printing viscosity in different environments; through optimization of an acrylate oligomer compounding system and the like, the dot reproduction precision is remarkably improved, and the pattern definition and the detail reduction capacity are greatly enhanced; a compound photo-initiation system is matched with a specific illumination process, so that the curing efficiency is greatly improved, and the production efficiency is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of inks, in particular to a highly stable UV ink and a preparation method thereof. Background Art

[0002] As an environmentally friendly ink, UV ink has been widely used in printing, packaging and other fields due to its advantages such as fast drying speed, high gloss and good wear resistance. However, existing UV inks still have some problems during use, such as poor viscosity stability. The ink viscosity easily changes under different temperatures and shear rates, resulting in unstable printing quality. Summary of the Invention

[0003] In view of the deficiencies of the prior art, the present invention provides a highly stable UV ink, which solves the above-mentioned problems of the existing UV ink by optimizing the selection and reasonable proportioning of the various components of the ink and adopting a special preparation process.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a highly stable UV ink, composed of the following components, by weight: 40-60 parts of acrylate oligomer, 20-30 parts of active diluent monomer, 5-10 parts of photoinitiator, 10-15 parts of pigment, 1-3 parts of dispersant, 3-8 parts of stimulus-responsive viscosity regulator and 0.5-2 parts of additive.

[0005] Preferably, the preparation method of the stimulus-responsive viscosity modifier comprises the following steps: Step (a): dissolving 10-15 parts of dimethylaminoethyl methacrylate (temperature-sensitive unit), 5-8 parts of perfluorooctylethyl acrylate (shear-sensitive unit), and 2-4 parts of a photoresponsive spiro compound (photoresponsive unit) in supercritical CO2; Step (b): reacting at 55-65 MPa and 45-55° C. for 1.5-2.5 hours; Step (c): Gradual pressure reduction at a rate of 5 MPa / 10 min to normal pressure to obtain microcapsules with a particle size of 0.5-2 μm.

[0006] Preferably, the preparation steps of the photoresponsive spiro compound are as follows: Step (d) reacting 2-nitrobenzaldehyde with morpholinopropylamine in ethanol under reflux for 3 hours to generate a Schiff base intermediate; Step (e) under argon protection, reacting the intermediate with 2-hydroxy-1-naphthaldehyde at 120° C. for 6 hours; Step (f) Purification by column chromatography, eluent: ethyl acetate and petroleum ether in a volume ratio of 1:5, to obtain purple crystals.

[0007] Preferably, the molar ratio of dimethylaminoethyl methacrylate, perfluorooctyl ethyl acrylate and the photoresponsive spiro compound is 1.5-2.0:1:0.5-0.8.

[0008] Preferably, the acrylate oligomer is a mixture of polyurethane acrylate and epoxy acrylate in a mass ratio of 2.5-3.5:1.

[0009] Preferably, the reactive diluent monomer comprises trimethylolpropane triacrylate (TMPTA) and ethoxylated bisphenol A diacrylate (EO-BPADA) in a mass ratio of 2-3:1.

[0010] Preferably, the auxiliary agent is composed of the following components in parts by weight: 0.3-1 part of an organosilicon leveling agent, 0.1-0.5 part of a hindered amine light stabilizer, and 0.1-0.5 part of a fluorine surfactant.

[0011] Preferably, the dispersant is polyester-modified polydimethylsiloxane and BYK-163 in a mass ratio of 2:1, and the photoinitiator comprises acylphosphine oxide and α-hydroxyketone in a mass ratio of 3:1.

[0012] A method for preparing UV ink comprises the following steps: Step (1) pre-dispersing the stimulus-responsive viscosity modifier in 40-50% of the total active diluent monomer, and ultrasonically treating the mixture at a power of 300-500 W and a frequency of 40 kHz for 20-40 minutes; Step (2) adding pigment and dispersant, and ball milling with zirconium oxide beads (Φ0.3-0.5 mm) at a grinding chamber temperature of 20°C for 2-4 hours to a particle size D50 ≤ 2 μm; Step (3) Under nitrogen protection, add the acrylate oligomer and the remaining monomers in three stages at 25-45° C., with an interval of 15-25 minutes between each stage; Step (4) Add photoinitiator and auxiliary agent, and stir at a constant speed for 1-1.5 hours under blue light irradiation at a wavelength of 405nm and a light intensity of 10-15mW / cm².

[0013] Preferably, the three-stage gradient addition in step (3) is specifically as follows: Stage 1: Add 30-40% acrylate oligomer at 25°C and stir at 300-400 rpm; Second stage: add 30-40% acrylate oligomer at 35°C, stirring speed 500-600 rpm; The third stage: adding the remaining components at 45°C, stirring at a rate of 800-1000 rpm.

[0014] Compared with the existing technology, the present invention provides a highly stable UV ink and a preparation method thereof, which has the following beneficial effects: through the stimulus-responsive viscosity regulator pre-dispersion process combined with its core-shell structure design, the viscosity change rate of the ink is controlled at 5.2% or below, ensuring rheological stability under different environments and printing conditions.

[0015] The innovative pigment ball milling dispersion technology and compound dispersant work synergistically to increase the dot reproduction rate to over 92%, which is approximately 10% higher than commercially available inks. This effectively eliminates dot blurring and deformation problems, and meets the high-precision requirements of high-end printing.

[0016] The combination of gradient feeding and blue light excitation process increases the curing speed to over 12m / min, which is over 20% faster than the traditional process, significantly shortening the production cycle and improving printing efficiency.

[0017] Excellent wear resistance: By optimizing molecular mixing and cross-linking processes, the friction fastness reaches level 4 and above, which is 1-2 levels higher than traditional inks, greatly enhancing the durability of printed products and reducing wear and discoloration. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a picture of the product prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0019] 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 creative efforts are within the scope of protection of the present invention.

[0020] 1. Viscosity stability test Reference Standards: Currently, there are no unified national standards specifically for UV ink viscosity stability at specific temperatures and times. This test primarily references general ink stability testing methods and common industry practices. To assess ink stability at different temperatures, physical properties, such as gelation, roughening, and viscosity changes, are often observed after a specific period of temperature exposure.

[0021] Test steps: Prepare several clean, dry containers with sealed lids, accurately weigh appropriate amounts of UV ink samples to be tested, and record the initial mass.

[0022] Place the container containing the ink sample in an oven at a constant temperature of 40°C, with the oven temperature fluctuation range controlled within ±1°C. During the placement process, ensure that the sample containers are placed stably and do not interfere with each other.

[0023] After 30 days in the oven, remove the container and wait for the ink sample temperature to return to room temperature (25°C). During this process, the container can be placed in a room with a stable temperature to cool naturally for at least 2 hours.

[0024] Viscosity measurements are performed using a calibrated rotational viscometer. Before measurement, select an appropriate spindle and speed combination based on the expected viscosity range of the ink sample to ensure the measurement result is within the effective measurement range of the viscometer. Slowly and vertically immerse the viscometer spindle into the ink sample to the required depth. Start the viscometer and measure for the time specified in the instrument's operating manual. Record the measured viscosity value.

[0025] Calculate the viscosity change rate using the formula: Viscosity change rate = (viscosity after 30 days - initial viscosity) / initial viscosity × 100%. The initial viscosity is the viscosity value of the ink sample measured at room temperature before being stored at 40°C.

[0026] 2. Dot Reproducibility Test Reference standards: Refer to the general methods and relevant industry standards for dot reproducibility evaluation in the printing industry, such as the dot quality assessment specifications developed by some printing associations for different printing processes and ink types, which mainly focus on indicators such as dot shape, size accuracy, and clarity at a specific screen count.

[0027] Test steps: Prepare or select a standard 200LPI printing test plate containing dot patterns of different shapes (circular, square, diamond, etc.) and different area percentages (such as 10%, 30%, 50%, 70%, 90%, etc.). The material, surface roughness and other parameters of the test plate must meet the general standards of the printing industry to ensure that it can accurately reflect the dot transfer performance of the ink in actual printing.

[0028] Install the UV ink to be tested on a printing machine that meets industry standards and adjust all parameters of the printing machine to standard conditions, including but not limited to printing pressure, ink supply, and printing speed. Printing pressure should be adjusted according to the printing plate and substrate type used to ensure uniform pressure and good ink transfer. The ink supply should be adjusted to ensure that the dots are printed clearly and completely on the substrate without ink accumulation or dot loss. The printing speed should be set to the recommended speed range for this type of UV ink and substrate during normal production of the printing machine.

[0029] Print on selected substrates (typically industry-standard printing paper or film) on a printing device, printing at least five sheets to ensure the reliability of the test results. During the printing process, closely monitor the operating status of the printing device to ensure a stable and stable printing process with no abnormal fluctuations.

[0030] After printing, wait for the ink to completely dry and cure (for UV inks, standard UV curing equipment can be used to ensure consistent curing conditions). Use a calibrated magnifying glass with a certain magnification (e.g., 10-20x) or a professional dot detector to observe and measure the dots on the printed product. For dot clarity, observe whether the dot edges are clear and sharp, and whether there is any blurring or ghosting. For dot accuracy, measure the actual area of ​​dots at different area percentages, compare it with the theoretical value, and calculate the percentage of dot expansion or reduction.

[0031] Dot reproduction rate is expressed as a percentage using the formula: Dot Reproduction Rate = (Total Area of ​​Actual Accurately Reproduced Dots / Total Area of ​​Theoretical Dots) × 100%. The total area of ​​actual accurately reproduced dot is calculated by adding the areas of dots of varying area percentages whose shapes and sizes meet standard requirements. The total theoretical area of ​​dot is calculated based on the area of ​​the designed dot pattern on the test pattern.

[0032] 3. Curing speed test Reference standards: Refer to industry test standards related to UV ink curing speed, such as the test specifications for UV ink curing performance on standard printing equipment developed by some ink manufacturer associations, and guidance documents on UV curing system performance evaluation provided by printing equipment manufacturers.

[0033] Test steps: Install the UV ink to be tested on standard printing equipment equipped with a standard UV curing lamp. Ensure that the UV curing lamp's model, power, wavelength, and other parameters meet industry standards and that the lamp is within its specified validity period to ensure stable luminous performance. At the same time, inspect and debug the printing equipment's transmission system and ink delivery system to ensure normal operation.

[0034] Select industry-standard substrates, such as common printing paper or plastic film, and install them on the paper or film transport device of the printing equipment.

[0035] Adjust the printing speed of the printing equipment, starting at a lower speed, such as 5m / min. During the printing process, observe the curing state of the ink on the printed material to determine whether the ink is fully cured. This can be determined by the following method: Gently wipe the printed area with a clean cotton ball or soft cloth. If the cotton ball or soft cloth is not stained with ink and the ink surface is dry, smooth, and not sticky, the ink is considered fully cured. If there is ink stain, it means that the ink is not fully cured.

[0036] Gradually increase the printing speed by 1 m / min each time. Repeat the above printing and inspection process until you find the highest printing speed at which the ink is completely cured. This speed is the curing speed of the UV ink, measured in m / min. During the test, keep other printing parameters (such as ink supply, printing pressure, UV curing lamp power and exposure time, etc.) constant.

[0037] 4. Rubbing fastness test Reference Standards: The ISO 2409 cross-cut method and related industry standards for printing ink rubbing fastness testing are primarily referenced. The ISO 2409 cross-cut method is commonly used to evaluate the adhesion of coatings or inks to substrates. By simulating a certain degree of friction, the ink's discoloration and wear are observed, indirectly reflecting the ink's rubbing fastness.

[0038] Test steps: Print the UV ink to be tested on a substrate that meets industry standards, forming a uniform, smooth ink film. After printing, place the printed material under standard environmental conditions (temperature 23°C, relative humidity 50±5%) for drying and curing. The curing time is determined based on the characteristics of the UV ink and standard requirements to ensure that the ink is fully cured.

[0039] Use a single-edged cross-cutting tool that meets the requirements of ISO 2409. Select the appropriate cross-cutting spacing based on the thickness of the ink film (generally, 1mm for thinner films and 2mm or 3mm for thicker films). Cut the ink film with steady pressure, appropriate spacing, and a constant speed, penetrating the substrate surface. Create a series of parallel cuts. Then, make additional, parallel cuts at a 90° angle, intersecting the previous cuts to form a grid.

[0040] Use a soft-bristled brush to gently clean the surface of the crossed area to remove ink debris from cutting.

[0041] Select a transparent pressure-sensitive tape of appropriate width (e.g., 15mm or 25mm) that meets standard requirements, such as 3M600 tape. Apply one end of the tape evenly to the center of the crossed-out area. Use your fingers or a dedicated pressure roller to apply even pressure to the tape, ensuring full contact and a secure bond between the tape and the ink film. After application, hold the tape in place for at least 20 seconds to allow for good adhesion.

[0042] Grab one end of the tape and quickly tear it apart at a 60° angle within 0.5-1.0 seconds. Keep your movements steady and continuous to avoid shaking or uneven pulling.

[0043] Observe the ink film within the cross-cut area for any fading or wear, and assess the rubbing fastness according to the standards. The rubbing fastness scale is generally categorized on a scale of 0-5, with 0 indicating no detachment, optimal adhesion, and the highest rubbing fastness; 5 indicates near-complete detachment, poor adhesion, and the lowest rubbing fastness. For specific assessment, refer to the images or text provided in the standards to compare the cross-cut area after testing and determine its rubbing fastness grade.

[0044] Related instruments introduction: Constant temperature oven, model: DHG-9070A, purpose description: used to treat UV ink samples at a constant temperature of 40°C for 30 days, providing a stable high temperature environment for testing. The temperature fluctuation range can be controlled within ±1°C to ensure consistency of test conditions.

[0045] Rotational Viscometer, Model: Brookfield DV2T, Usage: Measure the viscosity of ink samples before and after treatment by selecting the appropriate rotor and speed combination. During measurement, the rotor is vertically immersed in the ink sample. The instrument's principle converts the viscous resistance experienced by the rotor into a viscosity value. This instrument can accurately measure inks of varying viscosity ranges, ensuring that the measurement results are within the valid range.

[0046] Standard printing equipment, model: Heidelberg SpeedmasterCX102, Usage: Used to print the UV ink to be tested on the substrate. This equipment can precisely adjust parameters such as printing pressure, ink supply, and printing speed to ensure printing under standard conditions. The printed dot pattern truly reflects the ink's dot transfer performance and has high repeatability, ensuring reliable test results.

[0047] UV curing equipment, common model: PhoseonFireEdge, Usage: Cures printed ink, provides stable and industry-standard UV curing conditions, such as specific wavelength, light intensity and exposure time, to ensure that the ink is completely dried and cured under the same conditions, avoiding the impact of insufficient curing on the test results of dot reproducibility.

[0048] Magnifiers or dot detectors, common models include the Mitutoyo BHM-150 (magnifier) ​​and the X-Ritee Xact2 (dot detector). Used for observing and measuring dots on printed materials. A magnifier, at 10-20x magnification, allows for intuitive observation of dot edge clarity and ghosting. A dot detector accurately measures the actual area of ​​dots with varying area percentages. By comparing this to theoretical values, it calculates the percentage of dot enlargement or reduction, allowing for accurate assessment of dot reproduction.

[0049] Standard printing equipment, model: Heidelberg SpeedmasterCX102, Instructions: Used to install the UV ink to be tested and perform printing operations. By gradually adjusting the printing speed, the curing performance of the ink at different speeds can be tested. The stable operation of the equipment and precise parameter control help to accurately determine the maximum printing speed at which the ink is completely cured, that is, the curing speed.

[0050] UV curing lamp, model: Hamamatsu LC8 (for use with printing equipment), Usage: As the core component of the UV curing system, it provides ultraviolet light of a specific wavelength and power for ink curing. Its model, power, wavelength, and other parameters meet general industry standards. If used within the validity period, it can ensure stable luminous performance, ensuring that the ink receives sufficient and consistent curing energy during the printing process.

[0051] Cotton balls or soft cloths (no specific model), as long as they meet the cleanliness and softness standards, are used. During the printing process, gently wiping the ink-printed area with a cotton ball or soft cloth can be used to determine whether the ink is fully cured based on whether it is stained with ink and the ink surface condition (dry, smooth, and non-sticky). This is a simple and effective tool for detecting the curing state.

[0052] Single-edged cross-cutting tool, Model: QFH, Instructions: Select the appropriate cross-cutting spacing (1mm, 2mm, or 3mm) based on the ink film thickness and perform the cross-cutting operation on the ink film of the printed product. Cutting at a constant speed creates a cross-cutting pattern to simulate a certain degree of friction, providing a test basis for subsequent evaluation of the ink film's adhesion and friction resistance.

[0053] Soft-bristle brush, no specific model, as long as the bristles are soft and clean. Usage: After the grid operation, it is used to gently clean the surface of the grid area to remove ink debris generated by cutting, so as to prevent the debris from interfering with subsequent test steps (such as applying tape) and result evaluation.

[0054] Transparent pressure-sensitive tape, model number: 3M600. Instructions: Apply the tape evenly to the crossed-out area, applying even pressure to ensure full contact and secure adhesion to the ink film. Then, quickly tear the tape to simulate actual friction in use. The friction fastness grade is assessed based on the discoloration and wear of the ink film.

[0055] Pressure roller, model: Rhopoint 5kg pressure roller, usage: When applying the tape, use the pressure roller to apply uniform pressure on the tape to ensure good adhesion between the tape and the ink film, making the test process more standardized and the results more reliable.

[0056] Example 1 A highly stable UV ink comprises, by weight, 40 parts of an acrylate oligomer (polyurethane acrylate to epoxy acrylate in a mass ratio of 2.5:1), 20 parts of a reactive diluent monomer (trimethylolpropane triacrylate to ethoxylated bisphenol A diacrylate in a mass ratio of 2:1), 5 parts of a photoinitiator (acylphosphine oxide to α-hydroxyketone in a mass ratio of 3:1), 10 parts of a pigment, 1 part of a dispersant (polyester-modified polydimethylsiloxane to BYK-163 in a mass ratio of 2:1), 3 parts of a stimuli-responsive viscosity modifier (dimethylaminoethyl methacrylate, perfluorooctyl ethyl acrylate to a photoresponsive spiro compound in a molar ratio of 1.5:1:0.5), and 0.5 parts of additives (0.3 parts of a silicone leveling agent, 0.1 parts of a hindered amine light stabilizer, and 0.1 parts of a fluorine-based surfactant).

[0057] Prepare UV ink according to the above preparation method: Step (1) pre-dispersing the stimulus-responsive viscosity modifier in 40% of the total active diluent monomer, and ultrasonically treating the mixture at a power of 300 W and a frequency of 40 kHz for 20 minutes; Step (2) adding pigment and dispersant, and ball milling with zirconium oxide beads (Φ0.3 mm) at a grinding chamber temperature of 20°C for 2 hours to a particle size D50 ≤ 2 μm; Step (3) under nitrogen protection, the acrylate oligomer and the remaining monomers were added in three stages at 25-45°C, with an interval of 15 minutes between each stage. The first stage: 30% of the acrylate oligomer was added at 25°C, with a stirring rate of 300 rpm; the second stage: 30% of the acrylate oligomer was added at 35°C, with a stirring rate of 500 rpm; the third stage: the remaining components were added at 45°C, with a stirring rate of 800 rpm; Step (4) Add photoinitiator and auxiliary agent, and stir at a constant speed for 1 hour under blue light irradiation with a wavelength of 405 nm and a light intensity of 10 mW / cm².

[0058] Example 2 A highly stable UV ink comprises, by weight, 50 parts of an acrylate oligomer (polyurethane acrylate to epoxy acrylate in a 3:1 mass ratio), 20 parts of a reactive diluent monomer (trimethylolpropane triacrylate to ethoxylated bisphenol A diacrylate in a 2:1 mass ratio), 5 parts of a photoinitiator (acylphosphine oxide to α-hydroxyketone in a 3:1 mass ratio), 10 parts of a pigment, 1 part of a dispersant (polyester-modified polydimethylsiloxane to BYK-163 in a 2:1 mass ratio), 3 parts of a stimuli-responsive viscosity modifier (dimethylaminoethyl methacrylate, perfluorooctyl ethyl acrylate to a photoresponsive spiro compound in a 1.5:1:0.5 molar ratio), and 0.5 parts of additives (0.3 parts of a silicone leveling agent, 0.1 parts of a hindered amine light stabilizer, and 0.1 parts of a fluorine-based surfactant).

[0059] Prepare UV ink according to the above preparation method: Step (1) pre-dispersing the stimulus-responsive viscosity modifier in 40% of the total active diluent monomer, and ultrasonically treating the mixture at a power of 300 W and a frequency of 40 kHz for 20 minutes; Step (2) adding pigment and dispersant, and ball milling with zirconium oxide beads (Φ0.3 mm) at a grinding chamber temperature of 20°C for 2 hours to a particle size D50 ≤ 2 μm; Step (3) under nitrogen protection, the acrylate oligomer and the remaining monomers were added in three stages at 25-45°C, with an interval of 15 minutes between each stage. The first stage: 30% of the acrylate oligomer was added at 25°C, with a stirring rate of 300 rpm; the second stage: 30% of the acrylate oligomer was added at 35°C, with a stirring rate of 500 rpm; the third stage: the remaining components were added at 45°C, with a stirring rate of 800 rpm; Step (4) Add photoinitiator and auxiliary agent, and stir at a constant speed for 1 hour under blue light irradiation with a wavelength of 405 nm and a light intensity of 10 mW / cm².

[0060] Example 3 A highly stable UV ink comprises, by weight, 40 parts of an acrylate oligomer (polyurethane acrylate to epoxy acrylate in a mass ratio of 2.5:1), 25 parts of a reactive diluent monomer (trimethylolpropane triacrylate to ethoxylated bisphenol A diacrylate in a mass ratio of 2.5:1), 5 parts of a photoinitiator (acylphosphine oxide to α-hydroxyketone in a mass ratio of 3:1), 10 parts of a pigment, 1 part of a dispersant (polyester-modified polydimethylsiloxane to BYK-163 in a mass ratio of 2:1), 3 parts of a stimuli-responsive viscosity modifier (dimethylaminoethyl methacrylate, perfluorooctyl ethyl acrylate to a photoresponsive spiro compound in a molar ratio of 1.5:1:0.5), and 0.5 parts of additives (0.3 parts of a silicone leveling agent, 0.1 parts of a hindered amine light stabilizer, and 0.1 parts of a fluorine-based surfactant).

[0061] Prepare UV ink according to the above preparation method: Step (1) pre-dispersing the stimulus-responsive viscosity modifier in 40% of the total active diluent monomer, and ultrasonically treating the mixture at a power of 300 W and a frequency of 40 kHz for 20 minutes; Step (2) adding pigment and dispersant, and ball milling with zirconium oxide beads (Φ0.3 mm) at a grinding chamber temperature of 20°C for 2 hours to a particle size D50 ≤ 2 μm; Step (3) under nitrogen protection, the acrylate oligomer and the remaining monomers were added in three stages at 25-45°C, with an interval of 15 minutes between each stage. The first stage: 30% of the acrylate oligomer was added at 25°C, with a stirring rate of 300 rpm; the second stage: 30% of the acrylate oligomer was added at 35°C, with a stirring rate of 500 rpm; the third stage: the remaining components were added at 45°C, with a stirring rate of 800 rpm; Step (4) Add photoinitiator and auxiliary agent, and stir at a constant speed for 1 hour under blue light irradiation with a wavelength of 405 nm and a light intensity of 10 mW / cm².

[0062] Example 4 A highly stable UV ink comprises, by weight, 40 parts of an acrylate oligomer (polyurethane acrylate to epoxy acrylate in a mass ratio of 2.5:1), 20 parts of a reactive diluent monomer (trimethylolpropane triacrylate to ethoxylated bisphenol A diacrylate in a mass ratio of 2:1), 8 parts of a photoinitiator (acylphosphine oxide to α-hydroxyketone in a mass ratio of 3:1), 10 parts of a pigment, 1 part of a dispersant (polyester-modified polydimethylsiloxane to BYK-163 in a mass ratio of 2:1), 3 parts of a stimuli-responsive viscosity modifier (dimethylaminoethyl methacrylate, perfluorooctyl ethyl acrylate to a photoresponsive spiro compound in a molar ratio of 1.5:1:0.5), and 0.5 parts of additives (0.3 parts of a silicone leveling agent, 0.1 parts of a hindered amine light stabilizer, and 0.1 parts of a fluorine-based surfactant).

[0063] Prepare UV ink according to the above preparation method: Step (1) pre-dispersing the stimulus-responsive viscosity modifier in 40% of the total active diluent monomer, and ultrasonically treating the mixture at a power of 300 W and a frequency of 40 kHz for 20 minutes; Step (2) adding pigment and dispersant, and ball milling with zirconium oxide beads (Φ0.3 mm) at a grinding chamber temperature of 20°C for 2 hours to a particle size D50 ≤ 2 μm; Step (3) under nitrogen protection, the acrylate oligomer and the remaining monomers were added in three stages at 25-45°C, with an interval of 15 minutes between each stage. The first stage: 30% of the acrylate oligomer was added at 25°C, with a stirring rate of 300 rpm; the second stage: 30% of the acrylate oligomer was added at 35°C, with a stirring rate of 500 rpm; the third stage: the remaining components were added at 45°C, with a stirring rate of 800 rpm; Step (4) Add photoinitiator and auxiliary agent, and stir at a constant speed for 1 hour under blue light irradiation with a wavelength of 405 nm and a light intensity of 10 mW / cm².

[0064] Example 5 A highly stable UV ink comprises, by weight, 40 parts of an acrylate oligomer (polyurethane acrylate to epoxy acrylate in a mass ratio of 2.5:1), 20 parts of a reactive diluent monomer (trimethylolpropane triacrylate to ethoxylated bisphenol A diacrylate in a mass ratio of 2:1), 5 parts of a photoinitiator (acylphosphine oxide to α-hydroxyketone in a mass ratio of 3:1), 10 parts of a pigment, 1 part of a dispersant (polyester-modified polydimethylsiloxane to BYK-163 in a mass ratio of 2:1), 6 parts of a stimuli-responsive viscosity modifier (dimethylaminoethyl methacrylate, perfluorooctyl ethyl acrylate to a photoresponsive spiro compound in a molar ratio of 1.8:1:0.7), and 0.5 parts of additives (0.3 parts of a silicone leveling agent, 0.1 parts of a hindered amine light stabilizer, and 0.1 parts of a fluorine-based surfactant).

[0065] Prepare UV ink according to the above preparation method: Step (1) pre-dispersing the stimulus-responsive viscosity modifier in 40% of the total active diluent monomer, and ultrasonically treating the mixture at a power of 300 W and a frequency of 40 kHz for 20 minutes; Step (2) adding pigment and dispersant, and ball milling with zirconium oxide beads (Φ0.3 mm) at a grinding chamber temperature of 20°C for 2 hours to a particle size D50 ≤ 2 μm; Step (3) under nitrogen protection, the acrylate oligomer and the remaining monomers were added in three stages at 25-45°C, with an interval of 15 minutes between each stage. The first stage: 30% of the acrylate oligomer was added at 25°C, with a stirring rate of 300 rpm; the second stage: 30% of the acrylate oligomer was added at 35°C, with a stirring rate of 500 rpm; the third stage: the remaining components were added at 45°C, with a stirring rate of 800 rpm; Step (4) Add photoinitiator and auxiliary agent, and stir at a constant speed for 1 hour under blue light irradiation with a wavelength of 405 nm and a light intensity of 10 mW / cm².

[0066] Example 6 A highly stable UV ink comprises, by weight, 40 parts of an acrylate oligomer (polyurethane acrylate to epoxy acrylate in a mass ratio of 2.5:1), 20 parts of a reactive diluent monomer (trimethylolpropane triacrylate to ethoxylated bisphenol A diacrylate in a mass ratio of 2:1), 5 parts of a photoinitiator (acylphosphine oxide to α-hydroxyketone in a mass ratio of 3:1), 10 parts of a pigment, 1 part of a dispersant (polyester-modified polydimethylsiloxane to BYK-163 in a mass ratio of 2:1), 3 parts of a stimuli-responsive viscosity modifier (dimethylaminoethyl methacrylate, perfluorooctylethyl acrylate to photoresponsive spiro compound in a molar ratio of 1.5:1:0.5), and 1.5 parts of additives (0.7 parts of a silicone leveling agent, 0.3 parts of a hindered amine light stabilizer, and 0.5 parts of a fluorine-based surfactant).

[0067] Prepare UV ink according to the above preparation method: Step (1) pre-dispersing the stimulus-responsive viscosity modifier in 40% of the total active diluent monomer, and ultrasonically treating the mixture at a power of 300 W and a frequency of 40 kHz for 20 minutes; Step (2) adding pigment and dispersant, and ball milling with zirconium oxide beads (Φ0.3 mm) at a grinding chamber temperature of 20°C for 2 hours to a particle size D50 ≤ 2 μm; Step (3) under nitrogen protection, the acrylate oligomer and the remaining monomers were added in three stages at 25-45°C, with an interval of 15 minutes between each stage. The first stage: 30% of the acrylate oligomer was added at 25°C, with a stirring rate of 300 rpm; the second stage: 30% of the acrylate oligomer was added at 35°C, with a stirring rate of 500 rpm; the third stage: the remaining components were added at 45°C, with a stirring rate of 800 rpm; Step (4) Add photoinitiator and auxiliary agent, and stir at a constant speed for 1 hour under blue light irradiation with a wavelength of 405 nm and a light intensity of 10 mW / cm².

[0068] Comparative Example 1 A UV ink comprises, by weight, 40 parts of an acrylate oligomer (polyurethane acrylate to epoxy acrylate in a ratio of 2.5:1), 20 parts of a reactive diluent monomer (trimethylolpropane triacrylate to ethoxylated bisphenol A diacrylate in a ratio of 2:1), 5 parts of a photoinitiator (acylphosphine oxide to α-hydroxyketone in a ratio of 3:1), 10 parts of a pigment, 1 part of a dispersant (polyester-modified polydimethylsiloxane to BYK-163 in a ratio of 2:1), and 0.5 parts of additives (0.3 parts of a silicone leveling agent, 0.1 parts of a hindered amine light stabilizer, and 0.1 parts of a fluorine surfactant).

[0069] Prepare UV ink according to the above preparation method: Step (1) pre-dispersing the stimulus-responsive viscosity modifier in 40% of the total active diluent monomer, and ultrasonically treating the mixture at a power of 300 W and a frequency of 40 kHz for 20 minutes; Step (2) adding pigment and dispersant, and ball milling with zirconium oxide beads (Φ0.3 mm) at a grinding chamber temperature of 20°C for 2 hours to a particle size D50 ≤ 2 μm; Step (3) under nitrogen protection, the acrylate oligomer and the remaining monomers were added in three stages at 25-45°C, with an interval of 15 minutes between each stage. The first stage: 30% of the acrylate oligomer was added at 25°C, with a stirring rate of 300 rpm; the second stage: 30% of the acrylate oligomer was added at 35°C, with a stirring rate of 500 rpm; the third stage: the remaining components were added at 45°C, with a stirring rate of 800 rpm; Step (4) Add photoinitiator and auxiliary agent, and stir at a constant speed for 1 hour under blue light irradiation with a wavelength of 405 nm and a light intensity of 10 mW / cm².

[0070] Comparative Example 2 A UV ink comprises, by weight, 40 parts of an acrylate oligomer (polyurethane acrylate), 20 parts of a reactive diluent monomer (trimethylolpropane triacrylate and ethoxylated bisphenol A diacrylate in a mass ratio of 2:1), 5 parts of a photoinitiator (acylphosphine oxide and α-hydroxyketone in a mass ratio of 3:1), 10 parts of a pigment, 1 part of a dispersant (polyester-modified polydimethylsiloxane and BYK-163 in a mass ratio of 2:1), 3 parts of a stimuli-responsive viscosity modifier (dimethylaminoethyl methacrylate, perfluorooctylethyl acrylate and a photoresponsive spiro compound in a molar ratio of 1.5:1:0.5), and 0.5 parts of additives (0.3 parts of a silicone leveling agent, 0.1 parts of a hindered amine light stabilizer, and 0.1 parts of a fluorine-based surfactant).

[0071] Prepare UV ink according to the above preparation method: Step (1) pre-dispersing the stimulus-responsive viscosity modifier in 40% of the total active diluent monomer, and ultrasonically treating the mixture at a power of 300 W and a frequency of 40 kHz for 20 minutes; Step (2) adding pigment and dispersant, and ball milling with zirconium oxide beads (Φ0.3 mm) at a grinding chamber temperature of 20°C for 2 hours to a particle size D50 ≤ 2 μm; Step (3) under nitrogen protection, the acrylate oligomer and the remaining monomers were added in three stages at 25-45°C, with an interval of 15 minutes between each stage. The first stage: 30% of the acrylate oligomer was added at 25°C, with a stirring rate of 300 rpm; the second stage: 30% of the acrylate oligomer was added at 35°C, with a stirring rate of 500 rpm; the third stage: the remaining components were added at 45°C, with a stirring rate of 800 rpm; Step (4) Add photoinitiator and auxiliary agent, and stir at a constant speed for 1 hour under blue light irradiation with a wavelength of 405 nm and a light intensity of 10 mW / cm².

[0072] Comparative Example 3 A UV ink comprises, by weight, 40 parts of an acrylate oligomer (polyurethane acrylate to epoxy acrylate in a mass ratio of 2.5:1), 20 parts of a reactive diluent monomer (trimethylolpropane triacrylate), 5 parts of a photoinitiator (acylphosphine oxide to α-hydroxyketone in a mass ratio of 3:1), 10 parts of a pigment, 1 part of a dispersant (polyester-modified polydimethylsiloxane to BYK-163 in a mass ratio of 2:1), 3 parts of a stimuli-responsive viscosity modifier (dimethylaminoethyl methacrylate, perfluorooctylethyl acrylate to photoresponsive spiro compound in a molar ratio of 1.5:1:0.5), and 0.5 parts of additives (0.3 parts of a silicone leveling agent, 0.1 parts of a hindered amine light stabilizer, and 0.1 parts of a fluorine-based surfactant).

[0073] Prepare UV ink according to the above preparation method: Step (1) pre-dispersing the stimulus-responsive viscosity modifier in 40% of the total active diluent monomer, and ultrasonically treating the mixture at a power of 300 W and a frequency of 40 kHz for 20 minutes; Step (2) adding pigment and dispersant, and ball milling with zirconium oxide beads (Φ0.3 mm) at a grinding chamber temperature of 20°C for 2 hours to a particle size D50 ≤ 2 μm; Step (3) under nitrogen protection, the acrylate oligomer and the remaining monomers were added in three stages at 25-45°C, with an interval of 15 minutes between each stage. The first stage: 30% of the acrylate oligomer was added at 25°C, with a stirring rate of 300 rpm; the second stage: 30% of the acrylate oligomer was added at 35°C, with a stirring rate of 500 rpm; the third stage: the remaining components were added at 45°C, with a stirring rate of 800 rpm; Step (4) Add photoinitiator and auxiliary agent, and stir at a constant speed for 1 hour under blue light irradiation with a wavelength of 405 nm and a light intensity of 10 mW / cm².

[0074] Comparative Example 4 A UV ink comprises, by weight, 40 parts of an acrylate oligomer (polyurethane acrylate to epoxy acrylate in a mass ratio of 2.5:1), 20 parts of a reactive diluent monomer (trimethylolpropane triacrylate to ethoxylated bisphenol A diacrylate in a mass ratio of 2:1), 5 parts of a photoinitiator (acylphosphine oxide), 10 parts of a pigment, 1 part of a dispersant (polyester-modified polydimethylsiloxane to BYK-163 in a mass ratio of 2:1), 3 parts of a stimuli-responsive viscosity modifier (dimethylaminoethyl methacrylate, perfluorooctyl ethyl acrylate to a photoresponsive spiro compound in a molar ratio of 1.5:1:0.5), and 0.5 parts of additives (0.3 parts of a silicone leveling agent, 0.1 parts of a hindered amine light stabilizer, and 0.1 parts of a fluorine-based surfactant).

[0075] Prepare UV ink according to the above preparation method: Step (1) pre-dispersing the stimulus-responsive viscosity modifier in 40% of the total active diluent monomer, and ultrasonically treating the mixture at a power of 300 W and a frequency of 40 kHz for 20 minutes; Step (2) adding pigment and dispersant, and ball milling with zirconium oxide beads (Φ0.3 mm) at a grinding chamber temperature of 20°C for 2 hours to a particle size D50 ≤ 2 μm; Step (3) under nitrogen protection, the acrylate oligomer and the remaining monomers were added in three stages at 25-45°C, with an interval of 15 minutes between each stage. The first stage: 30% of the acrylate oligomer was added at 25°C, with a stirring rate of 300 rpm; the second stage: 30% of the acrylate oligomer was added at 35°C, with a stirring rate of 500 rpm; the third stage: the remaining components were added at 45°C, with a stirring rate of 800 rpm; Step (4) Add photoinitiator and auxiliary agent, and stir at a constant speed for 1 hour under blue light irradiation with a wavelength of 405 nm and a light intensity of 10 mW / cm².

[0076] Comparative Example 5 A UV ink comprises, by weight, 40 parts of an acrylate oligomer (polyurethane acrylate to epoxy acrylate in a mass ratio of 2.5:1), 20 parts of a reactive diluent monomer (trimethylolpropane triacrylate to ethoxylated bisphenol A diacrylate in a mass ratio of 2:1), 5 parts of a photoinitiator (acylphosphine oxide to α-hydroxyketone in a mass ratio of 3:1), 10 parts of a pigment, 1 part of a dispersant (polyester-modified polydimethylsiloxane), 3 parts of a stimuli-responsive viscosity modifier (dimethylaminoethyl methacrylate, perfluorooctylethyl acrylate to photoresponsive spiro compound in a molar ratio of 1.5:1:0.5), and 0.5 parts of additives (0.3 parts of a silicone leveling agent, 0.1 parts of a hindered amine light stabilizer, and 0.1 parts of a fluorine-based surfactant).

[0077] Prepare UV ink according to the above preparation method: Step (1) pre-dispersing the stimulus-responsive viscosity modifier in 40% of the total active diluent monomer, and ultrasonically treating the mixture at a power of 300 W and a frequency of 40 kHz for 20 minutes; Step (2) adding pigment and dispersant, and ball milling with zirconium oxide beads (Φ0.3 mm) at a grinding chamber temperature of 20°C for 2 hours to a particle size D50 ≤ 2 μm; Step (3) under nitrogen protection, add the acrylate oligomer and the remaining monomers at once, 45° C., and stir at a rate of 800 rpm; Step (4) Add photoinitiator and auxiliary agent, and stir at a constant speed for 1 hour under blue light irradiation with a wavelength of 405 nm and a light intensity of 10 mW / cm².

[0078] Comparative Example 6 A UV ink comprises, by weight, 40 parts of an acrylate oligomer (polyurethane acrylate to epoxy acrylate in a mass ratio of 2.5:1), 20 parts of a reactive diluent monomer (trimethylolpropane triacrylate to ethoxylated bisphenol A diacrylate in a mass ratio of 2:1), 5 parts of a photoinitiator (acylphosphine oxide to α-hydroxyketone in a mass ratio of 3:1), 10 parts of a pigment, 1 part of a dispersant (polyester-modified polydimethylsiloxane to BYK-163 in a mass ratio of 2:1), 3 parts of a stimuli-responsive viscosity modifier (dimethylaminoethyl methacrylate, perfluorooctyl ethyl acrylate to a photoresponsive spiro compound in a molar ratio of 1.5:1:0.5), and 0.5 parts of additives (0.3 parts of a silicone leveling agent, 0.1 parts of a hindered amine light stabilizer, and 0.1 parts of a fluorine-based surfactant).

[0079] Prepare UV ink according to the above preparation method: Step (1) pre-dispersing the stimulus-responsive viscosity modifier in 40% of the total active diluent monomer, and ultrasonically treating the mixture at a power of 300 W and a frequency of 40 kHz for 20 minutes; Step (2) adding pigment and dispersant, and ball milling with zirconium oxide beads (Φ0.3 mm) at a grinding chamber temperature of 20°C for 2 hours to a particle size D50 ≤ 2 μm; Step (3) under nitrogen protection, the acrylate oligomer and the remaining monomers were added in three stages at 25-45°C, with an interval of 15 minutes between each stage. The first stage: 30% of the acrylate oligomer was added at 25°C, with a stirring rate of 300 rpm; the second stage: 30% of the acrylate oligomer was added at 35°C, with a stirring rate of 500 rpm; the third stage: the remaining components were added at 45°C, with a stirring rate of 800 rpm; Step (4) Add photoinitiator and auxiliary agent, and stir at a constant speed for 1 hour under blue light irradiation with a wavelength of 405 nm and a light intensity of 10 mW / cm².

[0080] Comparative Example 7 Buy UV ink available on the market.

[0081] Table 1 is the ingredient list of Comparative Example 7 The UV inks obtained in Examples 1, 2, 3, 4, 5, 6 and Comparative Examples 1, 2, 3, 4, 5, 6 and 7 were grouped and numbered, respectively, as UM-BH-01, UM-BH-02, UM-BH-03, UM-BH-04, UM-BH-05, UM-BH-06, UM-BH-07, UM-BH-08, UM-BH-09, UM-BH-010, UM-BH-011, UM-BH-012, and UM-BH-013. The products of the examples and comparative examples were subjected to performance tests, specifically including viscosity stability (40°C / 30 days), viscosity change rate, dot reproducibility (200LPI), curing speed (m / min) and friction fastness (grade). The specific test results are shown in Tables 2 and 3.

[0082] Table 2 shows the test results of viscosity stability and dot reproducibility Table 3 shows the test results of curing speed and rubbing fastness Ultrasonic treatment uses the cavitation effect generated by high-frequency vibration to fully disperse the regulator microcapsules in the monomer, avoid agglomeration, ensure their uniform distribution in the ink system, and lay the foundation for the subsequent dynamic regulation effect.

[0083] Comparative Example 1, which did not include this modifier, exhibited a viscosity change rate of 18.7% after 30 days at 40°C. However, Examples 1 to 6, through this treatment step, effectively dispersed the modifier, keeping the viscosity change rate at or below 5.2%. This is because the uniformly dispersed modifier, with its core temperature-sensitive unit (dimethylaminoethyl methacrylate) and light-responsive unit, and its shell shear-sensitive unit (perfluorooctylethyl acrylate), can promptly respond to environmental changes at 25-45°C and a shear rate of 500-5000 s⁻¹. This allows for dynamic viscosity regulation through molecular conformational changes or interactions between groups, ensuring the rheological stability of the ink under various printing conditions.

[0084] The appropriate grinding chamber temperature avoids chemical reactions or property changes in some components of the ink caused by excessively high temperature. The grinding action of the zirconium oxide beads enables the pigment to be more finely dispersed in conjunction with the dispersant (polyester-modified polydimethylsiloxane and BYK-163 in a mass ratio of 2:1).

[0085] In the dot reproduction test, due to improper dispersion process or dispersant selection, the dot reproduction rates of Comparative Examples 1 to 6 were all below 90%, and the commercially available ink in Comparative Example 7 was 84%. However, after this treatment step, Examples 1 to 6 showed uniform pigment dispersion, improved ink fluidity and leveling, and dot reproduction rates of 92% or above, with the highest reaching 95%. This is because the finely dispersed pigment particles reduce light scattering and diffuse reflection, resulting in clear edges and regular shapes of printed dots, thereby improving the clarity and accuracy of the pattern and meeting the requirements of high-precision printing.

[0086] Step (3) Under nitrogen protection, add the acrylate oligomer and the remaining monomers in three stages at 25-45°C, with an interval of 15-25 minutes between each stage. In the first stage, add 30-40% of the acrylate oligomer at 25°C and stir at a low speed (300-400 rpm) to allow the oligomer to slowly blend into the system to avoid agglomeration due to local excessive concentration; in the second stage, heat the mixture to 35°C and add 30-40% of the oligomer and stir at a medium speed (500-600 rpm) to promote initial interaction between molecules; in the third stage, add the remaining components at 45°C and stir at a high speed (800-1000 rpm) to accelerate mixing. At the same time, this temperature is conducive to the movement of active groups in the oligomer and monomer, promoting pre-reaction and mutual entanglement between molecules.

[0087] Comparing the curing speed test data, Comparative Examples 1 to 6 all had curing speeds below 11 m / min due to improper addition methods or uncontrolled temperature, while Comparative Example 7 had a curing speed of 10 m / min. By using a gradient addition process, which resulted in more uniform mixing and enhanced intermolecular interactions, Examples 1 to 6 all achieved curing speeds of 12 m / min or higher, with the fastest reaching 14 m / min. In the rubbing fastness test, Examples 1 to 6 all achieved a rubbing fastness rating of 4 or higher, with the highest reaching 5, significantly outperforming the comparative examples. This is because the molecular structure formed by thorough mixing and pre-reaction allows for a denser, more robust cross-linked network to form during the subsequent curing process, enhancing the strength and abrasion resistance of the ink film.

[0088] Blue light irradiation provides the photoinitiator with a specific excitation wavelength, enabling it to efficiently absorb light energy and rapidly generate free radicals to initiate polymerization. The compounded photoinitiator system broadens the absorption spectrum and improves photoinitiation efficiency. The silicone leveling agent, hindered amine light stabilizer, and fluorosurfactant in the additives are evenly dispersed in the ink system during stirring, each performing its own function. The silicone leveling agent improves the ink's surface tension and leveling properties, the hindered amine light stabilizer enhances the ink's anti-aging properties, and the fluorosurfactant reduces surface energy, enhancing the ink's anti-fouling and abrasion resistance.

[0089] Through this treatment step, Examples 1 to 6 significantly outperformed the comparative examples in terms of curing speed and rubbing fastness. Curing speeds reached 12 m / min and above, and rubbing fastness reached level 4 and above, while the comparative examples exhibited curing speeds below 11 m / min and rubbing fastness levels of 3.5 and below. This demonstrates that this step significantly improves the curing efficiency and overall performance of the ink by optimizing the photoinitiation and additive dispersion processes.

[0090] In summary, the present invention achieves a synergistic improvement in multiple aspects of UV ink performance, such as viscosity stability, dot reproducibility, curing speed and friction fastness, through careful design and improvement of the preparation steps, from the microscopic molecular level to the macroscopic ink performance. Compared with traditional inks and comparative products, the present invention has significant technical advantages and application value.

[0091] The above are only specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications based on the present invention to solve substantially the same technical problems and achieve substantially the same technical effects are all included in the scope of protection of the present invention.

Claims

1. A highly stable UV ink, characterized in that: The invention is composed of the following components in parts by weight: 40-60 parts of acrylate oligomer, 20-30 parts of active diluent monomer, 5-10 parts of photoinitiator, 10-15 parts of pigment, 1-3 parts of dispersant, 3-8 parts of stimulus-responsive viscosity regulator and 0.5-2 parts of auxiliary agent.

2. The highly stable UV ink according to claim 1, characterized in that: The preparation method of the stimulus-responsive viscosity modifier comprises the following steps: Step (a): dissolving 10-15 parts of dimethylaminoethyl methacrylate, 5-8 parts of perfluorooctylethyl acrylate, and 2-4 parts of a photoresponsive spiro compound in supercritical CO2; Step (b): reacting at 55-65 MPa and 45-55° C. for 1.5-2.5 hours; Step (c): Gradual pressure reduction at a rate of 5 MPa / 10 min to normal pressure to obtain microcapsules with a particle size of 0.5-2 μm.

3. The high-stability UV ink according to claim 2, characterized in that: The preparation steps of the photoresponsive spiro compound are as follows: Step (d) reacting 2-nitrobenzaldehyde with morpholinopropylamine in ethanol under reflux for 3 hours to generate a Schiff base intermediate; Step (e) under argon protection, reacting the intermediate with 2-hydroxy-1-naphthaldehyde at 120° C. for 6 hours; Step (f) Purification by column chromatography, eluent: ethyl acetate and petroleum ether in a volume ratio of 1:5, to obtain purple crystals.

4. The high-stability UV ink according to claim 2, characterized in that: The molar ratio of the dimethylaminoethyl methacrylate, perfluorooctyl ethyl acrylate and the photoresponsive spiro compound is 1.5-2.0:1:0.5-0.

8.

5. The highly stable UV ink according to claim 1, characterized in that: The acrylate oligomer is a compound of polyurethane acrylate and epoxy acrylate in a mass ratio of 2.5-3.5:

1.

6. The highly stable UV ink according to claim 1, characterized in that: The active diluent monomer comprises trimethylolpropane triacrylate and ethoxylated bisphenol A diacrylate in a mass ratio of 2-3:

1.

7. The highly stable UV ink according to claim 1, characterized in that: The auxiliary agent is composed of the following components in parts by weight: 0.3-1 part of an organosilicon leveling agent, 0.1-0.5 part of a hindered amine light stabilizer, and 0.1-0.5 part of a fluorine surfactant.

8. The highly stable UV ink according to claim 1, characterized in that: The dispersant is a mixture of polyester-modified polydimethylsiloxane and BYK-163 in a mass ratio of 2:1, and the photoinitiator comprises acylphosphine oxide and α-hydroxyketone in a mass ratio of 3:

1.

9. A method for preparing UV ink according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step (1) pre-dispersing the stimulus-responsive viscosity modifier in 40-50% of the total active diluent monomer, and ultrasonically treating the mixture at a power of 300-500 W and a frequency of 40 kHz for 20-40 minutes; Step (2) adding pigment and dispersant, and ball milling with zirconium oxide beads at a grinding chamber temperature of 20° C. for 2-4 hours to a particle size D50 ≤ 2 μm; Step (3) Under nitrogen protection, add the acrylate oligomer and the remaining monomers in three stages at 25-45° C., with an interval of 15-25 minutes between each stage; Step (4) Add photoinitiator and auxiliary agent, and stir at a constant speed for 1-1.5 hours under blue light irradiation at a wavelength of 405nm and a light intensity of 10-15mW / cm².

10. The method for preparing UV ink according to claim 9, wherein: The three-stage gradient addition in step (3) is specifically as follows: Stage 1: Add 30-40% acrylate oligomer at 25°C and stir at 300-400 rpm; Second stage: add 30-40% acrylate oligomer at 35°C, stirring speed 500-600 rpm; The third stage: adding the remaining components at 45°C, stirring at a rate of 800-1000 rpm.

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