Printing ink formula with fluorescent effect and printing process
By preparing NaYF4 fluorescent materials with a particle size of less than 5μm and optimizing the printing process, the problem of low dot precision of fluorescent ink in cigarette packaging anti-counterfeiting was solved, and a printing effect with high fluorescence intensity and clear dots was achieved.
Patent Information
- Application Number
- CN202510922250.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-04
- Publication Date
- 2025-09-16
AI Technical Summary
Existing fluorescent inks for anti-counterfeiting of cigarette packaging have problems such as low dot precision, high viscosity, poor leveling, and unclear printing due to large fluorescent material particles.
By preparing NaYF4 fluorescent materials with a particle size of less than 5μm, potassium acetylacetonate or magnesium acetylacetonate is mixed with water-based polyurethane prepolymer to reduce viscosity and control crystal growth. Combined with vacuum treatment and optimized printing parameters, the uniform distribution of the fluorescent material in the ink is improved.
The ink printing accuracy is improved, the fluorescence intensity is increased, the quality of printed products is improved, and the dot clarity is enhanced.
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of anti-counterfeiting of cigarette packaging, and in particular to an ink formula and a printing process with a fluorescent effect. Background Art
[0002] Anti-counterfeiting has received increasing attention in the global packaging market, and developing an unbreakable anti-counterfeiting system has become an important challenge currently faced.
[0003] Photoluminescent labels, mainly made of fluorescent ink, are one of the current mainstream packaging anti-counterfeiting technologies. They have good concealment, strong anti-counterfeiting capabilities, simple preparation process, low cost, and do not require a large amount of equipment. They can be perfectly integrated with packaging design, packaging structure, information technology and artificial intelligence, and can push products and their packaging to new heights of development. Therefore, they have attracted much attention.
[0004] In the field of cigarette packaging anti-counterfeiting, trademark patterns can be created by overprinting regular ink with fluorescent ink. This ensures that under specific conditions (such as temperature fluctuations or changes in the wavelength of light excitation), only the fluorescent ink layer fluoresces, distinguishing it from the regular ink layer, thus achieving an effective anti-counterfeiting effect. Overprinting requires high precision for the fluorescent ink layer, but current fluorescent inks suffer from low dot accuracy. This is partly because fluorescent materials often have lower color rendering than regular pigments. To enhance the fluorescent layer, a higher amount of fluorescent material is typically used, increasing their viscosity and reducing their leveling properties. This makes transfer and spreading difficult during printing, resulting in unclear dot edges. Furthermore, to achieve a strong luminous effect, fluorescent pigment particles are typically larger than those of regular pigments. These larger particles are more difficult to transfer through fine cell meshes (gravure printing) or anilox rollers (flexographic printing), and are more likely to accumulate at dot edges, leading to dot enlargement and blurring. Summary of the Invention
[0005] The present invention aims to solve the above problems and provides an ink formula and printing process with high printing precision and fluorescent effect.
[0006] The technical solution to the problem solved by the present invention is, in a first aspect, to provide an ink formula with a fluorescent effect, comprising a binder, a solvent, an additive and a fluorescent material, wherein the fluorescent material is prepared by the following steps: S1. preparing a waterborne polyurethane prepolymer using diol, 2,2-dimethylol propionic acid, isocyanate, catalyst and chain extender as raw materials; S2. Potassium acetylacetonate or magnesium acetylacetonate, mixed with the aqueous polyurethane prepolymer, and allowed to stand for 20 to 24 hours to obtain a mixture; S3. Using the mixture as a polymer ligand, a NaYF4 fluorescent material is prepared by a hydrothermal method; the particle size of the fluorescent material does not exceed 5 μm.
[0007] In the present invention, potassium acetylacetonate or magnesium acetylacetonate is mixed with a waterborne polyurethane prepolymer, and the hydrogen bonds between the waterborne polyurethane prepolymer molecules are destroyed through the coordination effect of the metal ions and the carbonyl groups of the polyurethane, thereby reducing the viscosity of the waterborne polyurethane prepolymer. The viscosity-reduced mixture containing β-diketone, potassium ions or magnesium ions, and carboxyl groups is then used as a polymer ligand. The low viscosity facilitates the diffusion of the polymer ligand to adsorb rare earth ions. After adsorption, the β-diketone forms a complex with the rare earth ions in the early stage of the reaction, thereby regulating the growth of crystals and obtaining micron-sized crystals with uniform size. The carboxyl groups strongly chelate with the rare earth ions in the middle and late stages of the reaction, thereby delaying the release of the rare earth ions in the hydrothermal reaction, reducing the nucleation rate, and reducing crystal surface defects, thereby improving the fluorescence intensity of the crystals. The doping of potassium ions or magnesium ions causes the crystal lattice to expand or contract, thereby reducing the symmetry of the rare earth ions with respect to the surrounding chemical environment, and further increasing the fluorescence intensity. Finally, a fluorescent material with small and uniform particle size and high fluorescence intensity was obtained. The amount of this fluorescent material used in the ink can be reduced, thereby improving the printing dot accuracy of the ink.
[0008] In step S1 , the selection of diol is not limited. Preferably, the diol is selected from at least one of polycarbonate diol (PCDL), polytetramethylene glycol (PTMG), and polyoxypropylene glycol (PPG).
[0009] Preferably, the molecular weight of the diol does not exceed 1500. If the molecular weight is too large, the molecular weight of the obtained waterborne polyurethane prepolymer increases and is adsorbed on the crystal surface, affecting the fluorescence intensity of the crystal.
[0010] The selection of isocyanate is not limited. Preferably, the isocyanate is selected from at least one of isophorone diisocyanate (IPDI) and diphenyl toluene isocyanate (MDI).
[0011] Preferably, the molar ratio of the diol to the isocyanate is (1.5-3): 1. For example, it can be 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, or 3.0:1.
[0012] Preferably, the molar amount of the 2,2-dimethylolpropionic acid is 10% to 20% of the total molar amount of the diol and the isocyanate. For example, it can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%.
[0013] The choice of chain extender is not limited in principle. For example, the chain extender is 1,4-butanediol.
[0014] In some preferred embodiments, the chain extender includes 1,4-butanediol and tannic acid. Tannic acid, whose molecular structure contains 25 phenolic hydroxyl groups, 10 ester bonds, and one pyran heterocycle, is used as a crosslinker in the synthesis of polyurethane. The addition of tannic acid also makes the polyurethane fluorescent under ultraviolet light, further enhancing the material's fluorescence intensity.
[0015] Preferably, the molar ratio of 1,4-butanediol to tannic acid is (25-35): 1. For example, it can be 25:1, 26:1, 27:1, 28:1, 29:1, 30:1, 31:1, 32:1, 33:1, 34:1, or 35:1.
[0016] In step S2, preferably, when potassium acetylacetonate is used, the mass concentration of potassium ions in the mixture is 2% to 4%. For example, it can be 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, or 4%.
[0017] Preferably, when magnesium acetylacetonate is used, the mass concentration of magnesium ions in the mixture is 1% to 2%. For example, it can be 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2%.
[0018] Preferably, magnesium acetylacetonate is used to obtain a fluorescent material with higher fluorescence intensity.
[0019] After potassium acetylacetonate or magnesium acetylacetonate is mixed with the waterborne polyurethane prepolymer, it is necessary to allow the mixture to stand for the interaction between the two. For example, the standing time may be 20 hours, 21 hours, 22 hours, 23 hours, or 24 hours.
[0020] In step S3, a micron-sized material is obtained by a hydrothermal method.
[0021] Preferably, the hydrothermal temperature is 140-200° C. For example, it can be 140° C., 150° C., 160° C., 170° C., 180° C., 190° C., or 200° C.
[0022] The amount of fluorescent material in the ink formula can be reduced. Preferably, in parts by mass, the formula includes 40-50 parts of a binder, 20-30 parts of a solvent, 2-10 parts of an additive, and 10-15 parts of a fluorescent material. For example, the binder can be 40 parts, 41 parts, 42 parts, 43 parts, 44 parts, 45 parts, 46 parts, 47 parts, 48 parts, 49 parts, and 50 parts; the solvent can be 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, and 30 parts; the additive can be 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, and 10 parts; and the fluorescent material can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, and 15 parts.
[0023] Among them, preferably, the connecting material is selected from at least one of waterborne polyurethane, cross-linked modified waterborne polyurethane, and waterborne polyurethane modified by organic-inorganic hybrid materials.
[0024] Preferably, the solvent is water.
[0025] The selection of additives is not limited, and the additives are used to compensate for the deficiencies of the ink in terms of dispersibility, plasticity, weather resistance, etc. For example, the additives may include at least one of a leveling agent, a dispersant, a plasticizer, a heat stabilizer, and a light stabilizer.
[0026] For example, the leveling agent is selected from at least one of polyether-modified silicone, fluorine-modified acrylate, and mineral oil; the dispersant is selected from at least one of BYK-163 and S-100; the plasticizer is selected from at least one of diisodecyl adipate, tributyl phosphate, and dimethyl phthalate; the heat stabilizer is selected from at least one of methyl tin heat stabilizer, stearyl benzoylmethane, dibenzoylmethane, and epoxy butyl stearate; the light stabilizer is selected from at least one of 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-hexyloxyphenol, 2-hydroxy-4-n-octyloxybenzophenone, and bis(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate.
[0027] The ink preparation method is not limited, and can be prepared by a one-time mixing method or a batch mixing method.
[0028] In a second aspect, another object of the present invention is to provide a printing process for the above-mentioned ink formula with fluorescent effect, comprising the following steps: after the binder, solvent, additive and fluorescent material are made into ink, it is treated at a vacuum degree of 20~40kPa for 5~10 minutes and then used for overprinting.
[0029] The vacuum treatment step before printing uses vacuum to degas the ink. This process, during which bubbles rise, evenly distributes the fluorescent material throughout the ink, preventing it from settling and potentially affecting the quality of the printed product. Examples of vacuum levels include 20kPa, 25kPa, 30kPa, 35kPa, and 40kPa, and treatment times include 5, 6, 7, 8, 9, and 10 minutes.
[0030] Using the above-mentioned ink with a low content of fluorescent material can increase printing accuracy. Preferably, during overprinting, the printing pressure is 290-310N, the printing speed is 0.25-0.35m / min, and the screen speed is 175-200lpi. For example, the printing pressure can be 290N, 295N, 300N, 305N, or 310N; the printing speed can be 0.25m / min, 0.26m / min, 0.27m / min, 0.28m / min, 0.29m / min, 0.3m / min, 0.31m / min, 0.32m / min, 0.33m / min, 0.34m / min, or 0.35m / min; and the screen speed can be 175lpi, 180lpi, 185lpi, 190lpi, 195lpi, or 200lpi.
[0031] Beneficial effects of the present invention: 1. The present invention provides a fluorescent material and ink formulation. By using a mixture of potassium acetylacetonate or magnesium acetylacetonate and a waterborne polyurethane prepolymer as a polymer ligand for rare earth ions, a fluorescent material with small and uniform particle size and high fluorescence intensity can be obtained. The amount of this fluorescent material used in the ink can be reduced.
[0032] 2. The present invention provides a printing process using the above-mentioned ink formulation. Due to the low amount of fluorescent material in the ink, the screen speed can reach 175-200 lpi, improving printing precision. Furthermore, vacuum degassing is performed before printing, and the upward movement of bubbles is utilized to uniformly distribute the fluorescent material in the ink, thereby improving the quality of the printed product. DETAILED DESCRIPTION
[0033] The following are specific embodiments of the present invention and further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.
[0034] Example 1 A fluorescent ink formulation includes, by weight, 45 parts of a water-based polyurethane binder, 25 parts of deionized water as a solvent, 3 parts of diisodecyl adipate as a plasticizer, 2 parts of BYK-163 as a dispersant, and 15 parts of a fluorescent material. The ink is prepared by mixing the water-based polyurethane, water, plasticizer, dispersant, and fluorescent material and stirring at 3000 rpm until uniform.
[0035] The fluorescent material is prepared by the following steps: S1. Prepare polycarbonate diol with a molecular weight of 1000, dimethylolpropionic acid, isophorone diisocyanate, dibutyltin dilaurate catalyst, 1,4-butanediol chain extender, and acetone solvent. The molar ratio of polycarbonate diol, dimethylolpropionic acid, isophorone diisocyanate, and 1,4-butanediol is 1:0.6:2.5:0.5, and a sufficient amount of dibutyltin dilaurate is provided.
[0036] Mix polycarbonate diol with a small amount of acetone and a small amount of dibutyltin dilaurate catalyst and stir thoroughly. Then, add isophorone diisocyanate dropwise to the system and stir thoroughly at 45°C under a nitrogen atmosphere for 1 hour. Add 2,2-dimethylolpropionic acid and continue stirring thoroughly at 45°C for 1 hour. Set the temperature to 75°C, add a small amount of dibutyltin dilaurate catalyst, reflux for 3 hours, and cool to room temperature. Then, add 1,4-butanediol and a small amount of dibutyltin dilaurate, stir thoroughly, set the temperature to 65°C, reflux for at least 3 hours, and then add acetylacetone dropwise to cap the mixture to obtain a waterborne polyurethane prepolymer.
[0037] S2. Potassium acetylacetonate hemihydrate was purchased directly from the market and dispersed with aqueous ammonia at a volume concentration of 1.5% in a mass ratio of 10:90; the dispersion was then mixed with the aqueous polyurethane prepolymer prepared in step S1 in a mass ratio of 3:7 and allowed to stand for 22 hours to obtain a mixture.
[0038] S3. Dissolve YCl3·6H2O, YbCl3·6H2O, and Er(NO3)3 in water at a molar ratio of 39:10:1 to obtain a rare earth solution. Add the rare earth solution dropwise to the mixture prepared in step S2 while stirring. After the addition is complete, add an aqueous sodium fluoride solution in an amount 10 times the total molar amount of the rare earth elements. Stir for 30 minutes, then transfer the mixture to a reactor. After a sealed reaction at 180°C for 15 hours, cool, centrifuge, and collect the precipitate. Rinse the precipitate with 50% (volume fraction) ethanol solution and dry it at 80°C under vacuum for 12 hours to obtain the fluorescent material.
[0039] A printing process comprising the following steps: The ink prepared above was treated at a vacuum of 30 kPa for 8 minutes and then used for overprinting. During overprinting, the printing pressure was 300 N, the printing speed was 0.3 m / min, and the screen speed was 175 lpi.
[0040] Example 2 This embodiment is substantially the same as embodiment 1, with the only difference being that magnesium acetylacetonate is used.
[0041] Specifically, in step S2, magnesium acetylacetonate dihydrate is purchased directly from the market and dispersed with ammonia water having a volume concentration of 1.5% at a mass ratio of 10:90; then, the dispersion is mixed with the aqueous polyurethane prepolymer prepared in step S1 at a mass ratio of 1.5:8.5, and the mixture is allowed to stand for 22 hours to obtain a mixture.
[0042] Example 3 This embodiment is substantially the same as embodiment 2, the only difference being that the amount of magnesium acetylacetonate is different.
[0043] Specifically, in step S2, magnesium acetylacetonate dihydrate is purchased directly from the market and dispersed with ammonia water having a volume concentration of 1.5% at a mass ratio of 10:90; then, the dispersion is mixed with the aqueous polyurethane prepolymer prepared in step S1 at a mass ratio of 3:7, and the mixture is allowed to stand for 22 hours to obtain a mixture.
[0044] Example 4 This embodiment is substantially the same as embodiment 1, with the only difference being that the molecular weight of the polycarbonate diol is 1500.
[0045] Example 5 This embodiment is substantially the same as embodiment 1, with the only difference being that the molecular weight of the polycarbonate diol is 2000.
[0046] Example 6 This embodiment is substantially the same as embodiment 1, except that the chain extender comprises 1,4-butanediol and tannic acid, and the molar ratio of 1,4-butanediol to tannic acid is 30:1.
[0047] Specifically, in step S1, polycarbonate diol with a molecular weight of 1000, dimethylolpropionic acid, isophorone diisocyanate, a dibutyltin dilaurate catalyst, 1,4-butanediol, tannic acid, and an acetone solvent are prepared. The molar ratio of polycarbonate diol, dimethylolpropionic acid, isophorone diisocyanate, and 1,4-butanediol is 1:0.6:2.5:0.484:0.016, and a sufficient amount of dibutyltin dilaurate is provided.
[0048] Mix polycarbonate diol with a small amount of acetone and a small amount of dibutyltin dilaurate catalyst and stir thoroughly. Then, add isophorone diisocyanate dropwise to the system and stir thoroughly at 45°C under a nitrogen atmosphere for 1 hour. Add 2,2-dimethylolpropionic acid and continue stirring thoroughly at 45°C for 1 hour. Set the temperature to 75°C, add a small amount of dibutyltin dilaurate catalyst, reflux for 3 hours, and cool to room temperature. Then, add 1,4-butanediol, tannic acid, and a small amount of dibutyltin dilaurate. Stir thoroughly, set the temperature to 65°C, reflux for at least 3 hours, and then add acetylacetone dropwise to cap the mixture to obtain a waterborne polyurethane prepolymer.
[0049] Example 7 This example is essentially the same as Example 1, differing only in the amount of fluorescent material used in the ink formulation. In parts by mass, the ink formulation includes 50 parts of aqueous polyurethane as a binder, 25 parts of deionized water as a solvent, 3 parts of diisodecyl adipate as a plasticizer, 2 parts of BYK-163 as a dispersant, and 10 parts of the fluorescent material.
[0050] Example 8 This example is essentially the same as Example 1, differing only in the amount of fluorescent material used in the ink formulation. In parts by mass, the ink formulation includes 48 parts of aqueous polyurethane as a binder, 25 parts of deionized water as a solvent, 3 parts of diisodecyl adipate as a plasticizer, 2 parts of BYK-163 as a dispersant, and 12 parts of the fluorescent material.
[0051] Example 9 This example is essentially the same as Example 1, differing only in the amount of fluorescent material used in the ink formulation. In parts by mass, the ink formulation includes 30 parts of aqueous polyurethane as a binder, 25 parts of deionized water as a solvent, 3 parts of diisodecyl adipate as a plasticizer, 2 parts of BYK-163 as a dispersant, and 30 parts of the fluorescent material.
[0052] In this embodiment, due to the large amount of fluorescent material used, the screen speed needs to be reduced to 100 lpi during printing.
[0053] Comparative Example 1 This comparative example is basically the same as Example 1, except that potassium acetylacetonate is not added during the preparation of the fluorescent material.
[0054] Specifically, in step S2, deionized water and ammonia water with a volume concentration of 1.5% are mixed in a mass ratio of 10:90; then, the solution is mixed with the waterborne polyurethane prepolymer prepared in step S1 in a mass ratio of 3:7, and the mixture is allowed to stand for 22 hours to obtain a mixture.
[0055] Comparative Example 2 This comparative example is substantially the same as Example 1, except that potassium acetylacetonate is replaced by potassium chloride.
[0056] Specifically, in step S2, potassium chloride and ammonia water with a volume concentration of 1.5% are mixed in a mass ratio of 10:90; then, the solution is mixed with the aqueous polyurethane prepolymer prepared in step S1 in a mass ratio of 3:7, and the mixture is allowed to stand for 22 hours to obtain a mixture.
[0057] Comparative Example 3 This comparative example is substantially the same as Example 1, except that potassium acetylacetonate is replaced by acetylacetone.
[0058] Specifically, in step S2, acetylacetone was dispersed with ammonia water having a volume concentration of 1.5% at a mass ratio of 10:90; then, the dispersion was mixed with the aqueous polyurethane prepolymer prepared in step S1 at a mass ratio of 3:7, and the mixture was allowed to stand for 22 hours to obtain a mixture.
[0059] Comparative Example 4 This comparative example is basically the same as Example 1, and the only difference is that the printing process is different.
[0060] The ink in Example 1 is used for printing, and the printing process comprises the following steps: The ink was not vacuum treated and was directly used for overprinting. During overprinting, the printing pressure was 300N, the printing speed was 0.3m / min, and the screen speed was 175lpi.
[0061] Detection The fluorescence intensity of the fluorescent materials obtained in Example and Comparative Examples 1, 2, and 3 at 540 nm was detected, and the results are shown in Table 1 below.
[0062] The ink layer adhesion of the printed products obtained in Example 1 and Comparative Example 4 was tested in accordance with GB / T 13217.7-2023 Test Method for Ink Adhesion. The results are shown in Table 1 below.
[0063] Table 1. Fluorescence intensity I Peelability Example 1 7679 95% Example 2 8254 - Example 3 8012 - Example 4 7885 - Example 5 7702 - Example 6 7886 - Example 7 - - Example 8 - - Example 9 - - Comparative Example 1 6610 - Comparative Example 2 7118 - Comparative Example 3 6455 - Comparative Example 4 - 85% As shown in Table 1, the fluorescent material of the present application has good fluorescence intensity, so that its usage in the ink can be relatively low, making the ink at least suitable for overprinting at a screen speed of 175 lpi, thereby improving printing accuracy.
[0064] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the spirit of the present invention or exceeding the scope of the appended claims.
Claims
1. A formula of an ink having a fluorescent effect, comprising a binder, a solvent, an additive, and a fluorescent material, characterized in that: The fluorescent material is prepared by the following steps: S1. preparing a waterborne polyurethane prepolymer using diol, 2,2-dimethylol propionic acid, isocyanate, catalyst and chain extender as raw materials; S2. Potassium acetylacetonate or magnesium acetylacetonate, mixed with the aqueous polyurethane prepolymer, and allowed to stand for 20 to 24 hours to obtain a mixture; S3. Using the mixture as a polymer ligand, a NaYF4 fluorescent material is prepared by a hydrothermal method; the particle size of the fluorescent material does not exceed 5 μm.
2. The ink formulation with fluorescent effect according to claim 1, characterized in that: When the potassium acetylacetonate is used, the mass concentration of potassium ions in the mixture is 2% to 4%.
3. The ink formula with fluorescent effect according to claim 1, characterized in that: When the magnesium acetylacetonate is used, the mass concentration of magnesium ions in the mixture is 1% to 2%.
4. The ink formulation with fluorescent effect according to claim 1, characterized in that: The molecular weight of the diol does not exceed 1500.
5. The ink formula with fluorescent effect according to claim 1, characterized in that: The chain extender includes 1,4-butanediol and tannic acid.
6. The ink formula with fluorescent effect according to claim 5, characterized in that: The molar ratio of the 1,4-butanediol to the tannic acid is (25-35):
1.
7. The ink formula with fluorescent effect according to claim 1, characterized in that: In parts by mass, the composition comprises 40 to 50 parts of a binder, 20 to 30 parts of a solvent, 2 to 10 parts of an auxiliary agent, and 10 to 15 parts of a fluorescent material.
8. The ink formula with fluorescent effect according to claim 1, characterized in that: The connecting material is selected from at least one of waterborne polyurethane, cross-linked modified waterborne polyurethane, and waterborne polyurethane modified by organic-inorganic hybrid materials.
9. A printing process using the ink formulation with fluorescent effect according to any one of claims 1 to 8, characterized in that: After the linker, solvent, auxiliary agent and fluorescent material are made into ink, the ink is treated under a vacuum degree of 20-40 kPa for 5-10 minutes and then used for overprinting.
10. The printing process of the ink formulation with fluorescent effect according to claim 9, characterized in that: During overprinting, the printing pressure is 290~310N, the printing speed is 0.25~0.35m / min, and the screen speed is 175~200lpi.