Water-based fluorescent ink

Abstract

The embodiment of the invention provides water-based fluorescent ink. The water-based fluorescent ink is prepared from the following components in percentage by mass: 10 to 25 percent of fluorescent dye, 3 to 6 percent of organic pigment, 0.1 to 0.3 percent of nonionic oxidized high-density polyethylene wax emulsion, 0.3 to 0.7 percent of surfactant and the balance of auxiliaries, wherein the mass ratio of the fluorescent dye to the organic pigment is (3-6): 1. The water-based fluorescent ink can synergistically give consideration to both excellent fluorescent color development effect and good anti-back-penetration performance.

Description

Technical Field

[0001] This invention relates to the field of ink technology, and more specifically to a water-based fluorescent ink. Background Technology

[0002] Water-based fluorescent inks are widely used in marking, painting, advertising, security and anti-counterfeiting, and personalized design due to their vibrant colors and strong visual impact. These inks typically rely on fluorescent dyes to achieve their luminescent effect. However, traditional water-based fluorescent inks have inherent performance limitations, namely, the color rendering effect (fluorescence intensity) of the ink is difficult to balance with its application effect on specific substrates (such as polyethylene terephthalate film, hereinafter referred to as PET film).

[0003] Specifically, while water-based inks based on small-molecule fluorescent dyes offer high fluorescence efficiency and vibrant colors, they suffer from several drawbacks. Firstly, after film formation, these dyes tend to migrate and penetrate within the PET film, resulting in blurred printed outlines and severe "back-seepage" (ink seeping into the back of the PET film, affecting the appearance of both sides and subsequent processing). This defect significantly limits their application in high-end labels, transparent thin-film circuits, and other fields requiring precision printing. Secondly, water-based inks using pigments (usually polymer-coated phosphors) effectively mitigate migration and back-seepage issues due to their larger particle size, but their fluorescence and color rendering are generally inferior to those of small-molecule dyes. Furthermore, the luminescence intensity and color saturation of pigments are relatively low, failing to achieve the visual effects of small-molecule dyes and thus failing to meet the demands of applications requiring extremely high color rendering.

[0004] Therefore, there is an urgent need in the field to develop an aqueous fluorescent ink that can synergistically achieve excellent fluorescence color rendering and good anti-backlighting performance, thereby overcoming the above-mentioned defects of the prior art. Summary of the Invention

[0005] This invention provides an aqueous fluorescent ink that achieves a synergistic effect of excellent fluorescence color rendering and good anti-seepage performance.

[0006] This invention provides an aqueous fluorescent ink, comprising, by mass percentage: 10%-25% fluorescent dye, 3%-6% organic pigment, 0.1%-0.3% nonionic oxidized high-density polyethylene wax emulsion, 0.3%-0.7% surfactant, with the remainder being additives;

[0007] The mass ratio of the fluorescent dye to the organic pigment is (3-6):1.

[0008] In one possible implementation, the organic pigment is selected from any one or a combination of several of the following: green PG7, PG15; orange POr43, POr34; red PV19, PR254; and yellow PY74, PY128, PY150, PY155, and PY181.

[0009] In one possible implementation, the melting point of the nonionic oxidized high-density polyethylene wax emulsion is 120-150°C.

[0010] In one possible implementation, the nonionic oxidized high-density polyethylene wax emulsion is selected from any one or a combination of several of BYKAQUACER 528, BYK AQUACER 530, CLARIANT LICOWAX PE 520, and BASF LUWAX OA3.

[0011] In one possible implementation, the organic pigment has a particle size of 80-150 nm.

[0012] In one possible implementation, the surfactant is selected from any one or a combination of several of fluorocarbon surfactants and siloxane surfactants.

[0013] In one possible implementation, the surfactant is selected from any one or a combination of several of DOW DC-193, Capstone FS-31, Daikin TG656, TEGO WET 260, and TEGO GLIDE 410.

[0014] In one possible implementation, based on the water-based fluorescent ink, the additives comprise, by mass percentage: 15%-25% water-based polycarbonate polyurethane, 15%-25% organic solvent, 0.1%-0.5% bactericide, 0.1-0.2% pH adjuster, and the balance being deionized water.

[0015] In one possible implementation, the product comprises, by weight percentage: 15% of the fluorescent dye, 5% of the organic pigment, 0.3% of the nonionic oxidized high-density polyethylene wax emulsion, 0.5% of the surfactant, 20% of the waterborne polycarbonate polyurethane, 18% of the organic solvent, 0.2% of the bactericide, 0.1% of the pH adjuster, and the balance being deionized water.

[0016] In one possible implementation, the waterborne polycarbonate polyurethane is selected from any one or a combination of several of WPC-101, WPC-TX1, WPC-028, WS-6110, WS-6021, and RA-5300.

[0017] In one possible embodiment, the organic solvent is selected from any one or a combination of several of diethylene glycol, ethylene glycol, 1,5-pentanediol, polyethylene glycol with a molecular weight of 200-400, glycerol, propylene glycol, diethylene glycol butyl ether, and propylene glycol methyl ether.

[0018] In one possible implementation, the bactericide is PROXEL™ GXL;

[0019] In one possible implementation, the pH adjuster is triethanolamine.

[0020] The water-based fluorescent ink provided in this invention effectively overcomes the contradiction between achieving excellent fluorescence and resisting PET back-seepage in traditional technologies through the synergistic effect of specific components and a special mass ratio of fluorescent dyes and organic pigments. Specifically, the fluorescent dye ensures excellent fluorescence performance, while the organic pigments and non-ionic oxidized high-density polyethylene wax emulsion enhance the ink's adhesion and barrier properties on PET substrates, reducing back-seepage. Surfactants optimize dispersibility, and additives adjust overall performance. Ultimately, the ink exhibits both bright and long-lasting fluorescence on PET substrates and excellent back-seepage resistance, meeting the needs of PET-related printing applications. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] Addressing the technical challenge of existing fluorescent inks in achieving both excellent fluorescence rendering and good backsight resistance, the inventors conducted in-depth analysis and discovered that the core issue lies in the disordered selection of components and the lack of scientific control over their proportions. For example, simply increasing the amount of fluorescent dye to enhance color intensity can easily lead to dye aggregation that exceeds the coating capacity of the film-forming components, exacerbating the risk of backsight transmission. Conversely, blindly adding film-forming aids to strengthen backsight resistance will dilute the dye concentration, hinder the optical effects of fluorescent groups, and weaken color rendering performance.

[0023] Therefore, the inventors constructed a technical solution with the precise determination of the chemical composition of the ink and the proportion of each component as the core of the invention. By systematically regulating the types and content of fluorescent dyes, wax emulsions and other functional additives, a synergistic mechanism among the components was constructed, thereby achieving simultaneous optimization of color development performance and anti-backlight performance.

[0024] Based on this, embodiments of the present invention provide an aqueous fluorescent ink, comprising, by mass percentage: 10%-25% fluorescent dye, 3%-6% organic pigment, 0.1%-0.3% nonionic oxidized high-density polyethylene wax emulsion, 0.3%-0.7% surfactant, with the remainder being additives;

[0025] The mass ratio of fluorescent dye to organic pigment is (3-6):1.

[0026] In this embodiment, small molecule fluorescent dyes are the main fluorescent generators. The organic pigment particles are uniformly dispersed in the ink. On the one hand, their surfaces can physically adsorb and firmly "anchor" some of the free fluorescent dye molecules to their surfaces and the surrounding ink film. This greatly restricts the free migration of fluorescent dye molecules in the PET film and their penetration to the back of the film.

[0027] On the other hand, the uniformly distributed organic pigment particles and the non-ionic oxidized high-density polyethylene wax emulsion together form a dense microscopic physical barrier after film formation, effectively blocking the migration paths of anchored fluorescent dye molecules and a small number of free dye molecules, thereby significantly suppressing back-slip phenomenon. The addition of high-density polyethylene wax emulsion further enhances the performance of the ink film. Specifically, during the ink drying process, wax particles float to the surface of the ink film and form a very thin, dense hydrophobic protective layer. This wax film acts as a surface seal for the underlying ink layer; at the same time, the presence of wax particles enhances the hardness and abrasion resistance of the ink film, making the printed pattern more durable and less prone to damage from scratches, indirectly protecting the durability of the fluorescent color rendering effect.

[0028] This application's water-based fluorescent ink precisely combines components such as fluorescent dyes, organic pigments, and non-ionic oxidized high-density polyethylene wax emulsion, and controls the specific mass ratio of fluorescent dyes to organic pigments, specifically addressing the core pain point of the mutual incompatibility between fluorescent color rendering effect and anti-PET back-see-through performance in traditional technologies.

[0029] Among them, fluorescent dyes ensure that the ink has high brightness and long-lasting fluorescent color performance; organic pigments and wax emulsions work together to form a dense barrier layer, which enhances the adhesion of the ink to the PET substrate surface and significantly reduces the risk of back see-through; surfactants improve the uniformity of component dispersion, and additives optimize the ink's printability.

[0030] Ultimately, the ink achieves both high fluorescence color rendering and strong anti-seepage properties on PET substrates, exhibiting both bright and long-lasting fluorescence on PET substrates and excellent anti-seepage capabilities, solving the dilemma of traditional technologies and making it suitable for PET-related printing scenarios.

[0031] In one specific embodiment, the melting point of the nonionic oxidized high-density polyethylene wax emulsion is 120-150°C.

[0032] The melting point of the nonionic oxidized high-density polyethylene wax emulsion matches the heat transfer temperature during the printing process (typically 150-180℃). Specifically, when the heating element reaches the set heat transfer temperature, the nonionic oxidized high-density polyethylene wax emulsion melts rapidly, reducing the system viscosity and fully spreading and wetting the substrate. After cooling following the transfer, the molten nonionic oxidized high-density polyethylene wax emulsion solidifies quickly, forming a continuous, dense, and non-porous film structure on the substrate surface. This dense film effectively blocks fluorescent dye molecules from penetrating to the back of the substrate, significantly reducing the probability of ink back-slip, while improving the color adhesion and abrasion resistance of the printed pattern, ensuring the appearance quality and stability of the printed product.

[0033] This invention does not limit the specific selection of organic pigments, which can be any one or a combination of several of the following: green PG7, PG15; orange POr43, POr34; red PV19, PR254; and yellow PY74, PY128, PY150, PY155, and PY181.

[0034] The organic pigments provided in this embodiment are chemically stable, have good compatibility with water-based resin systems, and are easy to disperse to form stable suspensions, thus avoiding the problems of anchoring failure or ink stability reduction caused by pigment flocculation or sedimentation.

[0035] This invention does not limit the specific selection of fluorescent dyes; any one or a combination of several of the following can be used: DAYGLO's A / AX series, BRILLIANT's BFE series, and SINLOIHI's SF series. Specifically, the fluorescent dyes of the above-mentioned types exemplified in this application can achieve spectral complementarity and synergistic brightening, significantly improving the fluorescence intensity and color vibrancy of the printed pattern. Simultaneously, these dyes exhibit excellent compatibility with nonionic oxidized high-density polyethylene wax emulsions, enabling uniform dispersion in the system and avoiding uneven color development caused by dye aggregation, further optimizing the density and weather resistance of the transferred film.

[0036] This invention does not limit the specific selection of the nonionic oxidized high-density polyethylene wax emulsion, which can be any one or a combination of several of BYKAQUACER 528, BYK AQUACER 530, CLARIANT LICOWAX PE 520, and BASF LUWAX OA3.

[0037] This embodiment provides the selection of nonionic oxidized high-density polyethylene wax emulsion, which avoids charge reactions with anionic or cationic fluorescent dyes, resins or additives that may be present in the ink system, ensuring excellent chemical and storage stability of the entire formulation and preventing product failure due to demulsification and flocculation.

[0038] In one specific embodiment, the pigment particles of the organic pigment have a particle size of 80-150 nm.

[0039] Within this particle size range, organic pigment particles possess a sufficiently high specific surface area, providing a large number of active sites to efficiently anchor fluorescent dye molecules through physical adsorption. Furthermore, pigment particles in this size range can remain suspended for extended periods under Brownian motion, resisting sedimentation and clumping, thus ensuring the stability and uniformity of the ink.

[0040] In one specific embodiment, the surfactant is selected from any one or a combination of several of fluorocarbon surfactants and siloxane surfactants.

[0041] This embodiment optimizes ink printing smoothness, media compatibility, and high-temperature stability by combining and proportioning surfactants (fluorocarbon or siloxane-based) with nonionic oxidized high-density polyethylene wax emulsions. This combination avoids printhead needle breakage issues caused by other surfactants (such as acetylenic diol surfactants, which easily lead to decreased printing smoothness and abnormal viscosity during high-temperature storage), while simultaneously reducing back-seepage of PET films through the wax emulsion. This formulation provides low surface tension and sufficient kinetic stability.

[0042] This invention does not limit the specific choice of surfactant, which can be any one or a combination of several of DOW DC-193, Capstone FS-31, Daikin TG656, TEGO WET 260, and TEGO GLIDE 410. By selecting these specific surfactants, the wetting properties of the ink on different substrates (especially low surface energy PET films) can be specifically improved, the uniformity of the printed pattern can be improved, and the foam level can be controlled.

[0043] In one specific embodiment, based on water-based fluorescent ink, the additives by mass percentage include: 15%-25% water-based polycarbonate polyurethane, 15%-25% organic solvent, 0.1%-0.5% bactericide, 0.1-0.2% pH adjuster, and the balance being deionized water.

[0044] This embodiment achieves media compatibility of ink on PET film and cotton fabric by compounding waterborne polycarbonate polyurethane (WPU) with organic alcohol solvent. Specifically, WPU provides broad-spectrum adhesion and imparts excellent tensile strength, hardness, and chemical resistance to the film layer; while the organic alcohol solvent solves the potential smudging problem of WPU by promoting rapid curing and can temporarily lower the glass transition temperature of WPU, giving it better fluidity in the early stage of film formation and further enhancing adhesion.

[0045] In one specific embodiment, the product comprises, by weight percentage: 15% fluorescent dye, 5% organic pigment, 0.3% nonionic oxidized high-density polyethylene wax emulsion, 0.5% surfactant, 20% waterborne polycarbonate polyurethane, 18% organic solvent, 0.2% bactericide, 0.1% pH adjuster, and the balance being deionized water.

[0046] This invention, through the precise design and optimization of the addition amounts of each component, transforms the entire formulation from a simple mixture into a highly synergistic and functionally coupled organic whole. It not only successfully balances high fluorescence color development with excellent back-seepage resistance and exhibits outstanding compatibility with both PET and cotton fabrics, but also provides water-based fluorescent ink products with excellent storage stability, mechanical stability, and usage stability, meeting the demands of commercial production and high-quality applications.

[0047] This invention does not limit the specific selection of waterborne polycarbonate polyurethane, but can use any one or a combination of several of WPU-101, WPU-TX1, WPU-028, WS-6110, WS-6021, and RA-5300; by selecting these specific waterborne polycarbonate polyurethanes, the adhesion, durability, drying speed and fluorescence retention of ink on specific substrates can be specifically improved.

[0048] This invention does not limit the specific selection of organic solvents, which can be any one or a combination of several of the following: diethylene glycol, ethylene glycol, 1,5-pentanediol, polyethylene glycol with a molecular weight of 200-400, glycerol, propylene glycol, diethylene glycol butyl ether, and propylene glycol methyl ether. By selecting or combining these different solvents, the drying rate of the ink can be synergistically adjusted, the wettability and penetration of different substrates can be improved, and the resin film formation can be promoted, thereby taking into account printing smoothness, pattern quality, and media compatibility.

[0049] This invention does not limit the specific choice of bactericide, which can be 1,2-benzisothiazolin-3-one (BIT), for example, added in the form of the commercial product PROXEL™ GXL; this bactericide can effectively prevent the growth of microorganisms, ensure the long-term storage stability of ink, and has good compatibility with fluorescent components and other additives in the system, without affecting the fluorescent color development effect and physical properties of ink.

[0050] This invention does not limit the specific choice of pH adjuster; triethanolamine can be used. By adding triethanolamine, the pH value of the ink system is adjusted and stabilized within the neutral pH range. This not only effectively maintains the stability of the resin emulsion but also provides a more stable chemical environment for the fluorescent dye. Furthermore, the dispersing and wetting aid functions of triethanolamine further enhance the stability of the pigment dispersion system and the wetting properties of the ink on the substrate.

[0051] The technical solution of the present invention and how the technical solution of the present invention solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0052] 1. The specific components and their contents of the water-based fluorescent ink in the embodiments are shown in Table 1.

[0053] Table 1. Composition and content (%) of water-based fluorescent inks in each embodiment.

[0054]

[0055] Note: The parameters in Table 1 represent the percentage of the component in the total mass of the aqueous fluorescent ink of the corresponding embodiment.

[0056] 2. The specific components and their contents of the comparative water-based fluorescent inks are shown in Table 2.

[0057] Table 2. Composition and content (%) of water-based fluorescent inks in each comparative example

[0058]

[0059] Note: The parameters in Table 2 represent the percentage of the total mass of the corresponding component in the water-based fluorescent ink.

[0060] 3. Performance test results of the examples and comparative examples.

[0061] Inkjet flow, back-view effect, and color rendering test methods:

[0062] The water-based fluorescent inks prepared in the above embodiments and comparative examples were respectively printed on an EPSON I3200 four-head heat press printer. The printing medium was a heat-tearable double-sided PET heat press film. The test settings were 6-pass, high-speed bidirectional printing (continuous printing for 50m, testing solid color + pattern output). The nozzle status before and after printing, the back transparency after printing powder dissolution, and the fluorescent color development effect of the pattern after heat press transfer are detailed in Table 3 below.

[0063] Criteria for judging fluorescence color development effect: Irradiate the sample with a UV lamp with a wavelength between 360-500nm, and judge the fluorescence effect using a luminance meter based on the fluorescence color development brightness of the sample.

[0064] A color rendering brightness of 80 or above is considered excellent.

[0065] 70-80 is considered good;

[0066] 60-70 is considered passing;

[0067] A score below 60 is considered failing.

[0068] High-temperature stability test method: The aqueous fluorescent inks prepared in the comparative example and the example were placed in an aging oven at 60°C under the same conditions and aged for 15 days. The viscosity parameters before and after aging were tested and recorded, and the change rate was calculated to confirm the aging stability.

[0069] Among them, a change rate of less than 5% is considered acceptable.

[0070] The test results are shown in Table 3 below.

[0071] Table 3 Performance test results of water-based fluorescent inks in various embodiments and comparative examples

[0072]

[0073] As can be seen from Table 3:

[0074] The aqueous fluorescent inks prepared in Examples 1-6 have good effects in terms of fluorescence color development and anti-backlighting performance.

[0075] In Example 6 and Comparative Example 4, acetylenic diol surfactants were used, but no fluorocarbon or siloxane surfactants were added, resulting in a decrease in the ink's printing smoothness.

[0076] In Comparative Examples 1 and 4, where no polyethylene wax emulsion was added, the back-transparency of the PET film and the fluorescence color development effect decreased.

[0077] In Comparative Examples 2 and 5, the ratio of fluorescent dye to organic pigment was not between 3 and 6:1, and the fluorescence color development effect was not obvious.

[0078] In the comparative example 3, fluorescent dyes were added but no organic pigments were added, and the back-transparency phenomenon of the PET film was significantly aggravated.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A water-based fluorescent ink, characterized in that, The composition by mass percentage includes: 10%-25% fluorescent dye, 3%-6% organic pigment, 0.1%-0.3% nonionic oxidized high-density polyethylene wax emulsion, 0.3%-0.7% surfactant, and the remainder being additives; wherein the mass ratio of the fluorescent dye to the organic pigment is (3-6):

1.

2. The water-based fluorescent ink according to claim 1, characterized in that, The organic pigments are selected from any one or a combination of several of the following: green PG7, PG15; orange POr43, POr34; red PV19, PR254; and yellow PY74, PY128, PY150, PY155, and PY181.

3. The aqueous fluorescent ink according to claim 1 or 2, characterized in that, The melting point of the nonionic oxidized high-density polyethylene wax emulsion is 120-150℃.

4. The aqueous fluorescent ink according to any one of claims 1-3, characterized in that, The nonionic oxidized high-density polyethylene wax emulsion is selected from any one or a combination of several of BYK AQUACER 528, BYK AQUACER 530, CLARIANT LICOWAX PE 520, and BASFLUWAX OA3.

5. The aqueous fluorescent ink according to any one of claims 1-4, characterized in that, The organic pigment has a particle size of 80-150 nm.

6. The water-based fluorescent ink according to claim 5, characterized in that, The surfactant is selected from any one or a combination of several of fluorocarbon surfactants and siloxane surfactants.

7. The aqueous fluorescent ink according to any one of claims 5-6, characterized in that, The surfactant is selected from any one or a combination of several of the following: DOW DC-193, Capstone FS-31, Daikin TG656, TEGO WET 260, and TEGO GLIDE 410.

8. The aqueous fluorescent ink according to any one of claims 5-7, characterized in that, Based on the water-based fluorescent ink, the additives, by mass percentage, comprise: 15%-25% water-based polycarbonate polyurethane, 15%-25% organic solvent, 0.1%-0.5% bactericide, 0.1-0.2% pH adjuster, and the balance being deionized water.

9. The aqueous fluorescent ink according to claim 8, characterized in that, The composition, by weight percentage, includes: 15% of the fluorescent dye, 5% of the organic pigment, 0.3% of the nonionic oxidized high-density polyethylene wax emulsion, 0.5% of the surfactant, 20% of the waterborne polycarbonate polyurethane, 18% of the organic solvent, 0.2% of the bactericide, 0.1% of the pH adjuster, and the balance being deionized water.

10. The aqueous fluorescent ink according to any one of claims 8-9, characterized in that, The waterborne polycarbonate polyurethane is selected from any one or a combination of several of WPC-101, WPC-TX1, WPC-028, WS-6110, WS-6021, and RA-5300. And / or, the organic solvent is selected from any one or a combination of several of diethylene glycol, ethylene glycol, 1,5-pentanediol, polyethylene glycol with a molecular weight of 200-400, glycerol, propylene glycol, diethylene glycol butyl ether, and propylene glycol methyl ether; And / or, the bactericide is selected from PROXEL™ GXL; And / or, the pH adjuster is selected from triethanolamine.

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