Invisible fluorescent ink and its preparation method and application

Abstract

The application belongs to the technical field of anti-counterfeiting paint preparation, and particularly relates to a kind of invisible fluorescent inkjet material and its preparation method and application, invisible fluorescent inkjet material, by mass parts, including the following components: ultraviolet excitation fluorescent material 1-10 parts, adhesive 15-30 parts, penetration control agent 0.5-5 parts, heat-resistant stabilizer 0.1-2 parts, rheological modifier 0.1-1 part, water 50-85 parts;The penetration control agent includes silane coupling agent and high molecular penetration agent, and the mass ratio of silane coupling agent and high molecular penetration agent is 1-5:5-1;High molecular penetration agent is selected from polyethylene glycol, hydroxypropyl methyl cellulose or polyvinylpyrrolidone.The information of inkjet is invisible under visible light, and is developed clearly under specific wavelength ultraviolet light.

Description

Technical Field

[0001] This invention belongs to the field of anti-counterfeiting coating preparation technology, specifically relating to an invisible fluorescent inkjet printing material and its preparation method and application. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Decorative base paper is a special industrial paper that meets national standards. It is made from high-quality wood pulp and titanium dioxide as raw materials. After printing and impregnation, it is used as a decorative material for artificial boards. Due to its high value, there are counterfeit products on the market, so there is an urgent need for anti-counterfeiting technology.

[0004] Current anti-counterfeiting technologies for decorative base paper all have certain problems. For example, adding fluorescent anti-counterfeiting fibers during the papermaking process makes them visible under ultraviolet light. However, this method provides fixed anti-counterfeiting information, making it difficult to mark variable information (such as production batch, date, and unique code), and controlling the uniformity of fiber addition is also challenging.

[0005] Some anti-counterfeiting technologies involve printing patterns using water-based inks and ultraviolet fluorescent inks onto the decorative base paper before impregnation. While this method achieves fluorescent anti-counterfeiting, it relies on a printing process with fixed patterns. This cannot meet the production line's need for dynamic, variable information (such as QR codes or serial numbers) marking on each roll (or section) of base paper, and the investment and maintenance costs for printing equipment are relatively high.

[0006] Another anti-counterfeiting technology involves immersing an optical film in a phosphorescent solution, then crushing and grinding it into particles, which are finally mixed with various raw materials to create ink for spraying. This process is cumbersome, costly, and the resulting ink may not be suitable for high-speed coding equipment.

[0007] In addition, existing anti-counterfeiting technologies mainly focus on the physical protection of the printed code (such as coating), which makes it difficult to solve the technical problems of the printed pattern being easily diffused or disappeared after being subjected to subsequent high-temperature resin impregnation treatment. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the purpose of this invention is to provide an invisible fluorescent inkjet printing material, its preparation method, and its applications. The printed pattern information is invisible under visible light but clearly develops under ultraviolet light of a specific wavelength, effectively solving the technical problems of inkjet printing patterns easily diffusing or disappearing after subsequent high-temperature resin impregnation treatment.

[0009] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0010] In a first aspect, the present invention provides an invisible fluorescent coding material, comprising the following components by weight: 1-10 parts of ultraviolet-excited fluorescent material, 15-30 parts of adhesive, 0.5-5 parts of penetration control agent, 0.1-2 parts of heat-resistant stabilizer, 0.1-1 parts of rheology modifier, and 50-85 parts of water.

[0011] The permeation control agent includes a silane coupling agent and a polymeric permeation agent, with a mass ratio of silane coupling agent to polymeric permeation agent of 1-5:5-1;

[0012] The polymeric penetrant is selected from polyethylene glycol, hydroxypropyl methylcellulose, or polyvinylpyrrolidone.

[0013] Secondly, the present invention provides a method for preparing the stealth fluorescent inkjet coding material, comprising the following steps:

[0014] The ultraviolet laser fluorescent material, rheology modifier, part water and part penetration control agent are mixed and sheared to disperse, resulting in a uniform fluorescent slurry.

[0015] Mix the adhesive, heat stabilizer and remaining water evenly to obtain the main material;

[0016] The fluorescent paste is added to the main material in several batches, along with the remaining penetration control agent. The mixed solution is then homogenized and filtered to obtain the final product.

[0017] Thirdly, the present invention provides the application of the invisible fluorescent inkjet printing material in anti-counterfeiting of decorative base paper.

[0018] Fourthly, the present invention provides a method for preparing anti-counterfeiting marks on decorative base paper using the aforementioned invisible fluorescent coding material, comprising the following steps:

[0019] The invisible fluorescent inkjet printing material is printed onto the designated position of the decorative base paper, dried, impregnated with resin, dried, and cured.

[0020] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows:

[0021] The pattern printed using the inkjet printing material of this invention is completely invisible under normal conditions, without affecting the original appearance and printing performance of the decorative paper. Verification requires specialized equipment, resulting in a high anti-counterfeiting threshold.

[0022] For the high-temperature impregnation process that decorative base paper must undergo, the pattern printed using the inkjet printing material of this invention is firmly bonded to the paper fibers after curing, and can resist the penetration of resin solution and high-temperature baking, maintaining long-term clarity and stability.

[0023] The rheological properties of the inkjet printing material of this invention are adapted to standard industrial inkjet printers, enabling high-speed, online, and variable information printing, perfectly integrating into existing production processes without major equipment modifications.

[0024] The coding material of this invention uses water as the main solvent and does not contain volatile organic compounds (VOCs), making it friendly to the production environment and operators. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0026] Figure 1 This is a comparative schematic diagram of the decorative base paper after inkjet printing and impregnation treatment under ultraviolet light in an embodiment of the present invention. Detailed Implementation

[0027] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0028] Regarding the technical problems mentioned in the background section, existing anti-counterfeiting technologies primarily focus on the physical protection of the printed codes (such as adhesive coating). However, they struggle to address the challenges of diffusion and disappearance of the printed codes during subsequent high-temperature resin impregnation. As carriers of anti-counterfeiting information (such as production batch numbers, unique codes, and QR codes), the diffusion or disappearance of these codes directly renders the anti-counterfeiting marks unreadable. For example, the information may not be clearly readable under ultraviolet light, making it difficult to distinguish counterfeit products and negating the anti-counterfeiting protection for high-value products like decorative paper. Printed codes typically contain key information from the production process (such as batch numbers, dates, and production line numbers). If the codes diffuse or disappear, it disrupts the product's lifecycle traceability, making it impossible to quickly pinpoint the source of quality problems.

[0029] If the inkjet-printed pattern diffuses, it may leave a blurred mark under visible light, compromising the appearance consistency of the decorative base paper and reducing the product's aesthetics and market competitiveness. This is especially problematic for decorative base paper requiring subsequent printing and lamination; such appearance defects could lead to customer rejection and direct economic losses.

[0030] This invention provides an invisible fluorescent coding material, which, by weight, comprises the following components: 1-10 parts of ultraviolet-excited fluorescent material, 15-30 parts of binder, 0.5-5 parts of penetration control agent, 0.1-2 parts of heat-resistant stabilizer, 0.1-1 parts of rheology modifier, and 50-85 parts of water.

[0031] The permeation control agent includes a silane coupling agent and a polymeric permeation agent, with a mass ratio of silane coupling agent to polymeric permeation agent of 1-5:5-1;

[0032] The polymeric penetrant is selected from polyethylene glycol, hydroxypropyl methylcellulose, or polyvinylpyrrolidone.

[0033] Ultraviolet-excited fluorescent materials serve as carriers of anti-counterfeiting information. When excited by ultraviolet light of a specific wavelength, they emit visible light (red, green, blue, etc.) to achieve an "invisible-visible" effect.

[0034] The adhesive is used to firmly bond fluorescent materials to paper fibers. Its glass transition temperature (Tg) is higher than the resin impregnation temperature (180-220℃), ensuring that it does not soften or fall off at high temperatures.

[0035] Silane coupling agents act as a "bridging" agent, with their hydrophilic groups binding to the hydroxyl groups on the surface of paper fibers (cellulose) and their hydrophobic groups binding to the resin in the inkjet printing material, thereby "anchoring" the fluorescent mark to the fiber surface. Polymer penetrants, on the other hand, control the penetration speed and depth of the inkjet printing material into the paper by adjusting its surface tension and viscosity.

[0036] If only silane coupling agents are used, the inkjet printing material is prone to over-penetration, resulting in blurred markings and back-to-back transparency (see-through). If only polymeric penetrants are used, they may be washed away by the resin during subsequent impregnation due to insufficient adhesion. Using both in combination can balance penetration and adhesion, ensuring that the inkjet markings form a clear, firm, non-see-through, and resin-resistant pattern on the paper.

[0037] Antioxidants are used to capture free radicals generated by the resin during high-temperature impregnation, preventing the adhesive from oxidizing, degrading, and yellowing; light stabilizers are used to inhibit fluorescence quenching caused by ultraviolet light, extending the service life of anti-counterfeiting marks; the two work together to resist both thermal aging and photoaging, solving the problem of fluorescence intensity decay at high temperatures.

[0038] Rheology modifiers are used to adjust the viscosity of materials to suit industrial inkjet printers, ensuring that the printhead does not clog and the pattern remains continuous during high-speed printing.

[0039] The printed information using this inkjet printing material exhibits excellent durability, capable of withstanding subsequent impregnation processes on the decorative base paper (typically involving high temperatures of 150-220°C and resin penetration) without becoming blurred, diffused, disappearing, or reacting adversely with the resin.

[0040] In some embodiments, the invisible fluorescent coding material, by weight, comprises the following components: 5-10 parts of ultraviolet-excited fluorescent material, 20-30 parts of adhesive, 2-4 parts of penetration control agent, 1-2 parts of heat-resistant stabilizer, 0.5-1 part of rheology modifier, and 50-75 parts of water.

[0041] The permeation control agent includes a silane coupling agent and a polymeric permeation agent, with a mass ratio of 1-2:1-4.

[0042] The polymeric penetrant is selected from polyethylene glycol, hydroxypropyl methylcellulose, or polyvinylpyrrolidone.

[0043] Preferably, the invisible fluorescent coding material comprises, by weight, the following components: 5-10 parts of ultraviolet-excited fluorescent material, 20-30 parts of adhesive, 3-4 parts of penetration control agent, 1-1.5 parts of heat-resistant stabilizer, 0.5-1 part of rheology modifier, and 54-75 parts of water.

[0044] The permeation control agent includes a silane coupling agent and a polymeric permeation agent, with a mass ratio of silane coupling agent to polymeric permeation agent of 1:1-3;

[0045] The polymeric penetrant is selected from hydroxypropyl methylcellulose or polyvinylpyrrolidone.

[0046] In some embodiments, the ultraviolet-excited fluorescent material is a rare-earth-doped aluminate or silicate phosphor. Its excitation wavelength is around 254 nm or 365 nm, and the emitted light color can be selected from red, green, blue, etc.

[0047] Preferably, the rare earth element is at least one of europium (Eu), dysprosium (Dy), or manganese (Mn).

[0048] In some embodiments, the polymeric penetrant is selected from polyvinylpyrrolidone.

[0049] Preferably, the mass ratio of silane coupling agent to polymeric penetrant is 1-2:1-2.

[0050] In some embodiments, the adhesive is a waterborne acrylic resin, a waterborne polyurethane resin, or a mixture thereof, and the glass transition temperature of the adhesive is higher than the resin impregnation temperature.

[0051] In some embodiments, the heat stabilizer includes an antioxidant and a light stabilizer, wherein the mass ratio of the antioxidant to the light stabilizer is 1-3:1-3.

[0052] Heat stabilizers are used to prevent fluorescent materials from quenching or adhesives from aging during high-temperature processing.

[0053] Antioxidants primarily capture free radicals generated during high-temperature impregnation (180-220℃) of the resin, preventing yellowing and decreased adhesion caused by oxidative degradation of the adhesive. Light stabilizers (especially HALS) effectively prevent "fluorescence quenching" of fluorescent materials due to prolonged exposure to light (including UV lamps used for inspection) by capturing free radicals induced by UV light and decomposing hydrogen peroxide. Both address different aging factors during thermal processing and long-term use, respectively, jointly ensuring the thermal and optical stability of the marking throughout its lifespan.

[0054] Preferably, the antioxidant is a hindered phenol or a phosphite; the light stabilizer is a hindered amine.

[0055] In some embodiments, the silane coupling agent is γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, or vinyltrimethoxysilane.

[0056] Used to adjust the penetration depth of the inkjet printing material into the paper fibers, ensuring clear markings without penetrating the back of the paper.

[0057] In some embodiments, the rheology modifier is a polyurethane thickener or an alkali-swellable thickener.

[0058] Rheology modifiers are used to adjust the viscosity of materials to make them suitable for the printing requirements of piezoelectric or thermal inkjet printers.

[0059] Secondly, the present invention provides a method for preparing the stealth fluorescent inkjet coding material, comprising the following steps:

[0060] The ultraviolet laser fluorescent material, rheology modifier, part water and part penetration control agent are mixed and sheared to disperse, resulting in a uniform fluorescent slurry.

[0061] Mix the adhesive, heat stabilizer and remaining water evenly to obtain the main material;

[0062] The fluorescent paste is added to the main material in several batches, along with the remaining penetration control agent. The mixed solution is then homogenized and filtered to obtain the final product.

[0063] Ultraviolet laser fluorescent materials (especially at the nanoscale) are prone to agglomeration. If all raw materials are mixed at once, the phosphor is difficult to disperse evenly, leading to nozzle clogging during coding and resulting in bright spots or uneven luminescence. Pre-dispersion at high speed in a small amount of water and dispersant (partially a penetration control agent) can break down agglomerates and form a stable and uniform slurry, which is beneficial to improving the stability and reliability of the product and is the key to the preparation process.

[0064] In some embodiments, when preparing the fluorescent paste, the water used accounts for 20%-40% of the total water volume.

[0065] Thirdly, the present invention provides the application of the invisible fluorescent inkjet printing material in anti-counterfeiting of decorative base paper.

[0066] Fourthly, the present invention provides a method for preparing anti-counterfeiting marks on decorative base paper using the aforementioned invisible fluorescent coding material, comprising the following steps:

[0067] The invisible fluorescent inkjet printing material is printed onto the designated position of the decorative base paper, dried, impregnated with resin, dried, and cured.

[0068] In some embodiments, the drying process is infrared or hot air drying.

[0069] In some embodiments, after impregnation with resin, the resin is dried and cured at 180-210°C.

[0070] The present invention will be further described below with reference to the embodiments.

[0071] In the following examples and comparative examples, the hindered phenolic antioxidant, specifically ADK STAB AO-60 / AO-60RG, was purchased from Adicon (China) Investment Co., Ltd.

[0072] Hindered amine light stabilizer, Tiangang® HS-770 light stabilizer 770, purchased from Beijing Tiangang Additives Co., Ltd.

[0073] Polyurethane thickener, Sinuo SN-768 nonionic associative polyurethane thickener, purchased from Shanghai Sinuo New Materials Co., Ltd.

[0074] Example 1

[0075] An invisible fluorescent coding material, by weight, comprises the following components: 5 parts ultraviolet-excited fluorescent material, 20 parts adhesive, 3 parts penetration control agent, 1 part heat-resistant stabilizer, 1 part rheology modifier, and 70 parts water.

[0076] The permeation control agent includes a silane coupling agent and a polymeric permeation agent, with a mass ratio of 1:1 between the silane coupling agent and the polymeric permeation agent.

[0077] The polymeric penetrant is polyvinylpyrrolidone, and the silane coupling agent is γ-aminopropyltriethoxysilane;

[0078] The ultraviolet-excited fluorescent material is a rare-earth europium (Eu)-doped aluminate, with a europium doping concentration of 2.0 mol%.

[0079] The adhesive is a water-based acrylic resin;

[0080] The heat stabilizer includes antioxidants and light stabilizers, with a mass ratio of 2:3. The antioxidants are hindered phenolic antioxidants, and the light stabilizers are hindered amine light stabilizers.

[0081] The rheology modifier is a polyurethane thickener.

[0082] The preparation method of the above-mentioned stealth fluorescent inkjet printing material includes the following steps:

[0083] a. Pre-dispersion: The UV-excited fluorescent material is mixed with 30% of the total water volume of deionized water, rheology modifier and half of the amount of permeation control agent, and then subjected to high-speed shear dispersion to form a uniform fluorescent slurry.

[0084] b. Mixing of main ingredients: Under low-speed stirring at 400 rpm, add the high-temperature adhesive, heat-resistant stabilizer and the remaining deionized water into the reaction vessel and stir until homogeneous.

[0085] c. Blending: While stirring continuously, slowly add the fluorescent paste prepared in step (a) to the main mixture in step (b) (the volume of paste added per minute shall not exceed 10% of the initial volume of the main mixture, and stirring shall be carried out while adding to facilitate system homogenization and prevent local flocculation), and add the remaining permeation control agent at the same time.

[0086] d. Homogenization and Filtration: The mixed liquid is processed by a homogenizer and then filtered through a precision filter (5μm filter bag) to obtain the final invisible fluorescent inkjet coding material.

[0087] The application method of the above-mentioned inkjet printing material in the anti-counterfeiting production of decorative base paper includes the following steps:

[0088] a. Preparation of base paper: Unroll the unprinted decorative base paper (titanium white paper or plain paper).

[0089] b. Fluorescent inkjet printing: Before the impregnation process, an industrial inkjet printer is used to print invisible fluorescent inkjet printing material onto the set position of the base paper. The printed information is encrypted letters.

[0090] c. Drying: Infrared or hot air drying methods are used to quickly fix the coding area.

[0091] d. Impregnation and post-treatment: The inkjet-printed base paper is impregnated with melamine resin or urea-formaldehyde resin according to conventional processes, and then dried and cured at 200℃.

[0092] e. Testing and Inspection: The finished decorative paper shows no visible marks under natural light, which does not affect its appearance; however, the anti-counterfeiting information can be clearly read by irradiating it with a 254nm or 365nm ultraviolet lamp, such as... Figure 1 As shown.

[0093] Example 2

[0094] An invisible fluorescent coding material, by weight, comprises the following components: 10 parts of ultraviolet-excited fluorescent material, 30 parts of binder, 4 parts of penetration control agent, 1.5 parts of heat-resistant stabilizer, 0.5 parts of rheology modifier, and 54 parts of water.

[0095] The permeation control agent includes a silane coupling agent and a polymeric permeation agent, with a mass ratio of 1:3.

[0096] The polymeric penetrant is hydroxypropyl methylcellulose, and the silane coupling agent is γ-aminopropyltriethoxysilane;

[0097] The ultraviolet-excited fluorescent material is a rare-earth dysprosium (Dy)-doped aluminate, with a dysprosium doping concentration of 1.5 mol%.

[0098] The adhesive is a water-based acrylic resin;

[0099] The heat stabilizer includes antioxidants and light stabilizers, with a mass ratio of antioxidant to light stabilizer of 1:3. The antioxidant is a hindered phenolic antioxidant, and the light stabilizer is a hindered amine light stabilizer.

[0100] The rheology modifier is a polyurethane thickener.

[0101] The preparation method of the above-mentioned stealth fluorescent inkjet printing material includes the following steps:

[0102] a. Pre-dispersion: The UV-excited fluorescent material is mixed with 35% deionized water, rheology modifier and half of the permeation control agent, and then subjected to high-speed shear dispersion to form a uniform fluorescent slurry.

[0103] b. Mixing of main ingredients: Under low-speed stirring at 200 rpm, add the high-temperature adhesive, heat-resistant stabilizer and the remaining deionized water into the reaction vessel and stir until homogeneous.

[0104] c. Blending: While stirring continuously, slowly add the fluorescent paste prepared in step (a) to the main mixture in step (b), and add the remaining permeation control agent at the same time.

[0105] d. Homogenization and Filtration: The mixed liquid is processed by a homogenizer and then filtered through a precision filter (5μm filter bag) to obtain the final invisible fluorescent inkjet coding material.

[0106] Example 3

[0107] An invisible fluorescent coding material, by weight, comprises the following components: 5 parts of ultraviolet-excited fluorescent material, 15 parts of adhesive, 1 part of penetration control agent, 2 parts of heat-resistant stabilizer, 1 part of rheology modifier, and 76 parts of water.

[0108] The permeation control agent includes a silane coupling agent and a polymeric permeation agent, with a mass ratio of 2:1 between the silane coupling agent and the polymeric permeation agent.

[0109] The polymeric penetrant is polyethylene glycol, and the silane coupling agent is γ-aminopropyltriethoxysilane;

[0110] The ultraviolet-excited fluorescent material is a rare-earth manganese (Mn)-doped aluminate, with a rare-earth manganese doping concentration of 3.0 mol%.

[0111] The adhesive is a water-based acrylic resin;

[0112] The heat stabilizer includes antioxidants and light stabilizers, with a mass ratio of 3:1. The antioxidants are hindered phenolic antioxidants, and the light stabilizers are hindered amine light stabilizers.

[0113] The rheology modifier is a polyurethane thickener.

[0114] The preparation method of the above-mentioned stealth fluorescent inkjet printing material includes the following steps:

[0115] a. Pre-dispersion: The UV-excited fluorescent material is mixed with 25% deionized water, rheology modifier and half of the permeation control agent, and then subjected to high-speed shear dispersion to form a uniform fluorescent slurry.

[0116] b. Mixing of main ingredients: Under low-speed stirring at 500 rpm, add the high-temperature adhesive, heat-resistant stabilizer and the remaining deionized water into the reaction vessel and stir until homogeneous.

[0117] c. Blending: While stirring continuously, slowly add the fluorescent paste prepared in step (a) to the main mixture in step (b), and add the remaining permeation control agent at the same time.

[0118] d. Homogenization and Filtration: The mixed liquid is processed by a homogenizer and then filtered through a precision filter (5μm filter bag) to obtain the final invisible fluorescent inkjet coding material.

[0119] Example 4

[0120] The difference from Example 1 is that the polymeric penetrant polyvinylpyrrolidone is replaced with polyethylene glycol, while everything else is the same as in Example 1.

[0121] Example 5

[0122] The difference from Example 1 is that the polymeric penetrant polyvinylpyrrolidone is replaced with hydroxypropyl methylcellulose, while everything else is the same as in Example 1.

[0123] Example 6

[0124] The difference from Example 1 is that the silane coupling agent γ-aminopropyltriethoxysilane is replaced with γ-(2,3-epoxypropoxy)propyltrimethoxysilane, while all other aspects are the same as in Example 1.

[0125] Example 7

[0126] The difference from Example 1 is that the silane coupling agent γ-aminopropyltriethoxysilane is replaced with vinyltrimethoxysilane, while all other aspects are the same as in Example 1.

[0127] Comparative Example 1

[0128] The difference from Example 1 is that the polymeric penetrant is replaced with a silane coupling agent, while everything else is the same as in Example 1.

[0129] Comparative Example 2

[0130] The difference from Example 1 is that the silane coupling agent is replaced with a polymeric penetrant, while everything else is the same as in Example 1.

[0131] Comparative Example 3

[0132] The difference from Example 1 is that the polymeric penetrant polyvinylpyrrolidone is replaced with sodium fatty alcohol polyoxyethylene ether sulfate (AES), while all other aspects are the same as in Example 1.

[0133] Comparative Example 4

[0134] The difference from Example 1 is that the polymeric penetrant polyvinylpyrrolidone is replaced with sodium dodecylbenzenesulfonate (SDBS), while all other aspects are the same as in Example 1.

[0135] Comparative Example 5

[0136] The difference from Example 1 is that the silane coupling agent γ-aminopropyltriethoxysilane is replaced with methyltrimethoxysilane, while all other aspects are the same as in Example 1.

[0137] Comparative Example 6

[0138] The difference from Example 1 is that the silane coupling agent γ-aminopropyltriethoxysilane is replaced with phenyltrimethoxysilane, while all other aspects are the same as in Example 1.

[0139] Comparative Example 7

[0140] The difference from Example 1 is that the mass ratio of silane coupling agent to polymeric penetrant is 1:6; all other aspects are the same as in Example 1.

[0141] Comparative Example 8

[0142] The difference from Example 1 is that the mass ratio of silane coupling agent to polymeric penetrant is 6:1; all other aspects are the same as in Example 1.

[0143] The performance of the inkjet printing materials prepared in the examples and comparative examples was tested, and the test results are shown in Table 1:

[0144] (1) Marking morphology (transparency): Visual inspection and microscopic observation of the back of the paper after printing.

[0145] (2) Relative fluorescence intensity (initial): Measured by a fluorescence spectrophotometer, based on Example 1.

[0146] (3) Fluorescence intensity retention rate after impregnation: measured after impregnation using the standard impregnation process (200℃, 90s). Impregnation medium: melamine-formaldehyde resin impregnation liquid, solid content 50±2%, viscosity 25±5 seconds (Ford-4 cup, 25℃), pH value 9.0-9.5.

[0147] Fluorescence intensity retention rate (%) = I After soaking / I Before impregnation ×100%;

[0148] in: I Before impregnation: Fluorescence intensity of the sample under ultraviolet light excitation at a specific wavelength before impregnation treatment;

[0149] I After impregnation: Fluorescence intensity of the sample under the same conditions after impregnation treatment.

[0150] (4) Adhesion (cross-cut test): The cross-cut test of the tape was performed according to ASTM D3359 standard.

[0151] (5) Fluorescence quenching rate (used to characterize the thermal stability of the inkjet printing material): measured after aging in a 200℃ oven for 2 hours, fluorescence quenching rate (%) = (1 I t / I 0)×100%; where: I 0: Initial fluorescence intensity (before thermal aging). I t Fluorescence intensity after thermal aging for time t.

[0152] (6) Viscosity stability (used to characterize the inkjet printing suitability of inkjet printing materials): Examine the viscosity change after standing and the stability of continuous printing.

[0153] 1. Viscosity testing standards:

[0154] Test method: Refer to GB / T 2794-2013 "Determination of viscosity of adhesives", and use a rotational viscometer (Brookfield DV-II+ or equivalent equipment) at 25±0.5℃.

[0155] Specific parameters:

[0156] Rotor model: Select according to the estimated viscosity range (e.g., LV-3 or RV-4);

[0157] Rotational speed: 20 rpm;

[0158] Balancing time: 3 minutes;

[0159] Number of readings: Take 3 consecutive readings and average the results.

[0160] Evaluation criteria:

[0161] High viscosity: Viscosity value >500 mPa·s (25℃) makes it difficult for ink to supply ink to the inkjet printer, and problems such as broken lines and ink splatter are likely to occur during printing.

[0162] Low viscosity: Viscosity value <10 mPa·s (25℃) leads to unstable droplet shape and reduced printing accuracy;

[0163] Good viscosity: viscosity value in the range of 20-100 mPa·s (25℃), suitable for industrial inkjet printers.

[0164] 2. Settlement stability test standards

[0165] Test method: Refer to GB / T 6753.3-1986 "Test Method for Storage Stability of Coatings";

[0166] Specific steps:

[0167] The prepared inkjet printing material is loaded into a 100ml stoppered graduated cylinder, with the liquid level approximately 200mm.

[0168] Let stand at 25±2℃;

[0169] The height of the supernatant and the state of the precipitate were observed and recorded at 24h, 48h, 72h and 7d.

[0170] Evaluation criteria:

[0171] Easy to settle: Obvious stratification occurs within 24 hours, with the upper clear liquid height >10mm or the bottom sediment height >5mm;

[0172] Good stability: No obvious stratification within 7 days, or the height of the upper clear liquid is <5mm, and the precipitate is loose and can be easily redispersed.

[0173] 3. Liquidity Assessment Criteria

[0174] Test method: Use a Forte 4 cup viscometer (GB / T 1723-93);

[0175] Specific steps:

[0176] Adjust the temperature of the inkjet printing material to 25±1℃;

[0177] Block the nozzle of the 4-cup with your finger and fill the cup with the sample;

[0178] Quickly remove your finger and start the stopwatch at the same time;

[0179] Record the time (s) when the sample stream first interrupts;

[0180] Evaluation criteria:

[0181] Poor fluidity: Outflow time > 60 seconds indicates excessive viscosity, which is not conducive to printing.

[0182] Good fluidity: The outflow time is within the range of 15-30 seconds, indicating that it has suitable fluidity and leveling properties, making it suitable for industrial inkjet printing applications;

[0183] Excessive fluidity: outflow time <10 seconds indicates that the viscosity is too low, which can easily cause problems such as droplet tailing and diffusion during printing.

[0184] 4. Comprehensive evaluation of inkjet printing adaptability

[0185] Continuous printing stability test:

[0186] Load the coding material into an industrial inkjet printer (such as Videojet, Domino, etc.).

[0187] Print continuously for 4 hours under standard printing parameters (printing speed 100m / min, resolution 300dpi);

[0188] Check the print quality and printhead condition every 30 minutes.

[0189] Evaluation indicators:

[0190] Printhead clogging: If more than 3 printouts or printhead clogging occur during continuous printing, the machine must be stopped and cleaned.

[0191] Good stability: After 4 hours of continuous printing, the printing quality did not decrease significantly, and there was no need to clean the printhead.

[0192] Table 1. Relevant properties of the inkjet printing materials prepared in the examples and comparative examples.

[0193] Performance indicators Transparent Relative fluorescence intensity (initial) Fluorescence intensity retention rate after immersion (%) Adhesion Fluorescence quenching rate % Viscosity stability Example 1 No see-through back, sharp and clear edges 100% (set as baseline) 95% Grade 5B (No shedding) 5% Good, no settlement after 8 hours Example 2 No see-through back, sharp and clear edges 150% 98% Grade 5B (No shedding) 3% The viscosity is too high; parameters need to be adjusted. Example 3 Slightly see-through back, edges slightly blurred 90% 92% Grade 3B-4B (Minor detachment) 12% Best, with good liquidity Example 4 Clearly see-through back, blurred edges 98% 85% Grade 2B-3B (obvious peeling) 10% If the viscosity is too low, droplet tailing will occur during printing. Example 5 Clearly see-through back, blurred edges 100% 96% Grade 5B (No shedding) 12% High viscosity, poor flowability Example 6 No see-through back, sharp and clear edges 90% 85% Grade 5B (No shedding) 8% High viscosity, poor flowability, and broken printing lines. Example 7 Slightly see-through back, edges slightly blurred 85% 70% Grade 2B-3B (obvious peeling) 7% High viscosity, poor flowability Comparative Example 1 Severe transillumination, unidentifiable 100% The markings have been washed away and cannot be measured. Grade 0B-1B (Large-area peeling) not applicable It settles easily and clogs the nozzles. Comparative Example 2 No see-through back, clear edges 100% <20% (Severe loss) Grade 0B-1B (Large-area peeling) >50% Good, but the solvent is not environmentally friendly. Comparative Example 3 Clearly see-through back, blurred edges 85% <20% (Severe loss) Grade 0B-1B (Large-area peeling) 20% Viscosity fluctuates drastically and is unstable, causing ink droplets and ink splatter during printing. Comparative Example 4 Clearly see-through back, blurred edges <20% (Severe loss) <20% (Severe loss) Grade 0B-1B (Large-area peeling) 10% The viscosity is relatively low, the flowability is good, and the droplets tend to tail and spread during printing. Comparative Example 5 No see-through back, sharp and clear edges 85% 90% Grade 3B-4B (Minor detachment) >50% High viscosity, poor flowability Comparative Example 6 No see-through back, sharp and clear edges 70% 95% Grade 3B-4B (Minor detachment) 23% Low viscosity, excessively good fluidity Comparative Example 7 Clearly see-through back, blurred edges 76% <20% (Severe loss) Grade 0B-1B (Large-area peeling) >50% High viscosity, poor flowability Comparative Example 8 Slightly see-through back, edges slightly blurred 68% 35% Grade 0B-1B (Large-area peeling) 8% Too low viscosity, too high fluidity

[0194] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A stealth fluorescent inkjet printing material, characterized in that: By weight, it includes the following components: 5 parts UV-excited fluorescent material, 20 parts binder, 3 parts permeation control agent, 1 part heat stabilizer, 1 part rheology modifier, and 70 parts water. The permeation control agent includes a silane coupling agent and a polymeric permeation agent, with a mass ratio of 1:1 between the silane coupling agent and the polymeric permeation agent. The polymeric penetrant is polyvinylpyrrolidone; The silane coupling agent is γ-aminopropyltriethoxysilane; The heat stabilizer includes an antioxidant and a light stabilizer, with a mass ratio of antioxidant to light stabilizer of 2:3; the antioxidant is a hindered phenol; and the light stabilizer is a hindered amine.

2. The invisible fluorescent inkjet printing material according to claim 1, characterized in that: The ultraviolet-excited fluorescent material is a rare-earth-doped aluminate or silicate phosphor.

3. The invisible fluorescent inkjet printing material according to claim 1, characterized in that: The rheology modifier is a polyurethane thickener or an alkali-swellable thickener.

4. The method for preparing the stealth fluorescent inkjet printing material according to any one of claims 1-3, characterized in that: Includes the following steps: The ultraviolet laser fluorescent material, rheology modifier, part water and part penetration control agent are mixed and sheared to disperse, resulting in a uniform fluorescent slurry. Mix the adhesive, heat stabilizer and remaining water evenly to obtain the main material; The fluorescent paste is added to the main material in several batches, along with the remaining penetration control agent. The mixed solution is then homogenized and filtered to obtain the final product.

5. The method for preparing the stealth fluorescent inkjet printing material according to claim 4, characterized in that: When preparing fluorescent paste, the water used accounts for 20%-40% of the total water volume.

6. The application of the invisible fluorescent inkjet printing material according to any one of claims 1-3 in anti-counterfeiting of decorative base paper.

7. A method for preparing anti-counterfeiting marks on decorative base paper using the invisible fluorescent inkjet printing material according to any one of claims 1-3, characterized in that: Includes the following steps: The invisible fluorescent inkjet printing material is printed onto the designated position of the decorative base paper, dried, impregnated with resin, dried, and cured.

8. The method for preparing anti-counterfeiting marks on decorative base paper according to claim 7, characterized in that: After impregnation with resin, it is dried and cured at 180-210℃.

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