An ink-jet printable water-based rare earth complex invisible fluorescent ink, a photon glass, and a preparation method and application thereof
By preparing cross-linked polymer microspheres and using solid-phase extraction, the industrial-scale preparation of rare-earth complex photonic glass was achieved, filling the technological gap in the composite application of photonic glass and rare-earth complexes. This provides a high-security anti-counterfeiting ink with multi-color fluorescence and structural color effects, suitable for information encryption and optical anti-counterfeiting.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SUN YAT SEN UNIV
- Filing Date
- 2024-01-29
- Publication Date
- 2026-05-12
AI Technical Summary
In the existing technology, there are no reports on the composite application of photonic glass and rare earth complex luminescent materials, and there is a lack of water-based rare earth complex photonic glass inks suitable for industrial preparation. Anti-counterfeiting information is easily cracked and has low information content. There is a lack of inkjet printing inks that are simple to prepare and low in cost on the market.
By preparing submicron-sized polymer microspheres with a certain cross-linking structure, controlling the permeability of rare earth complexes, and doping with different rare earth complexes, the rare earth complexes are spontaneously incorporated into the microspheres using solid-phase extraction to form inkjet-printable rare earth complex photonic glass.
It achieves high-security anti-counterfeiting functions, is simple to operate, low in cost, suitable for industrial preparation, requires no expensive instruments, avoids volatile organic compound pollution, provides multi-color fluorescence and structural color effects, and is suitable for information encryption, optical anti-counterfeiting and specific identification.
Smart Images
Figure CN118085641B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of optical anti-counterfeiting ink technology. More specifically, it relates to an inkjet-printable water-based rare-earth complex invisible fluorescent ink, a water-based rare-earth complex photonic glass, its preparation method, and its application. Background Technology
[0002] In information storage / transmission, product authentication, and tamper detection, the adoption of simple, economical, and highly secure advanced technologies is an increasingly serious challenge facing the research community. Anti-counterfeiting labels with various fluorescent colors play a crucial role in information encryption and decryption. Fluorescent ink anti-counterfeiting technology is the preferred anti-counterfeiting technology for banknotes, tickets, and trademarks in various countries due to its advantages such as simple operation, low cost, convenient verification, and strong reproducibility.
[0003] Invisible ink, a type of anti-counterfeiting ink, is characterized by its superior concealment and enhanced anti-counterfeiting capabilities, and is widely used in the anti-counterfeiting printing of various tickets, documents, trademarks, and logos. In recent years, various materials, including small-molecule fluorescent substances, rare-earth oxides, rare-earth complexes, and carbon dots, have been widely applied in invisible anti-counterfeiting printing inks. Compared to small-molecule fluorescent substances and carbon dots, rare-earth complex luminescent materials have advantages such as high Stokes shift, weak visible light absorption, and high quantum efficiency. Furthermore, compared to inorganic luminescent powders of rare-earth oxides, rare-earth complexes offer advantages such as solubility and high compatibility with printing methods. However, the anti-counterfeiting level provided by a single fluorescent property remains very limited.
[0004] Photonic glass refers to a class of materials capable of producing non-rainbow coherent scattering. Compared to the rainbow structural colors produced by photonic crystals, gratings, and liquid crystals, photonic glass possesses unique non-rainbow structural color characteristics. Furthermore, its structural resonance varies with the angle between the incident and observation directions, exhibiting both angle-dependent and angle-independent structural colors. However, the application of photonic glass as a single material in anti-counterfeiting also presents several problems, such as the ease with which anti-counterfeiting information can be cracked and the limited information content.
[0005] However, there are currently no reports of combining photonic glass with rare earth complex luminescent materials and utilizing their structural color and fluorescence properties to achieve high-security anti-counterfeiting applications. In addition, there is a lack of water-based rare earth complex photonic glass inks on the market that are simple to prepare, low in cost, suitable for industrial production, and can be printed by inkjet printing. Summary of the Invention
[0006] This invention aims to provide an inkjet-printable ink with rare-earth fluorescence and structural color effects. It involves preparing submicron-sized polymer microspheres with a specific cross-linking structure, precisely controlling their cross-linking structure and size, and adjusting the permeation properties of rare-earth complexes. Furthermore, by doping different rare-earth complexes, a submicron-sized photonic glass with multicolor fluorescence excited by ultraviolet light can be achieved.
[0007] The first objective of this invention is to provide a method for preparing rare-earth complex photonic glass that can be printed by inkjet printing.
[0008] The second objective of this invention is to provide a rare-earth complex photonic glass prepared by the above-described preparation method.
[0009] The third objective of this invention is to provide an inkjet-printed invisible photonic glass anti-counterfeiting ink.
[0010] The fourth objective of this invention is to provide applications for the above-mentioned rare earth complex photonic glass and inkjet-printed invisible photonic glass anti-counterfeiting ink.
[0011] The above-mentioned objective of this invention is achieved through the following technical solution:
[0012] This invention provides a method for preparing rare earth complex photonic glass that can be inkjet printed. Microspheres are added to a rare earth complex solution and subjected to ultrasonication and vibration. The rare earth complex is spontaneously incorporated into the microspheres through solid-phase extraction. After centrifugation, the rare earth complex photonic glass is obtained.
[0013] Preferably, the ligand in the rare earth complex is any one or more of the following: potassium hydrogen tris(3-phenyl-5-methylpyrazol-1-yl)borate, bipyridine, 2-phenylpyridine, 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione, 4,4,4-trifluoro-1-(2-furanyl)-1,3-butanedione, 4,4-dibromo-bipyridine, terpyridine, and phenanthroline.
[0014] Preferably, the rare earth metal in the rare earth complex is any one of cerium, europium, terbium, or dysprosium. Specific choices include cerium trichloride hexahydrate, terbium trichloride, europium nitrate hexahydrate, or dysprosium chloride.
[0015] More specifically, as a preferred embodiment, the rare earth complex is any one of bis[potassium hydrogen tris(3-phenyl-5-methylpyrazol-1-yl)borate]cerium(III), (bipyridine)bis[2-phenylpyridine]terbium(III), (4,4-dibromo-bipyridine)tris[4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione]eupium(III), (phenanthroline)tris[4,4,4-trifluoro-1-(2-furanyl)-1,3-butanedione]eupium(III), and bis[terpyridine]dysprosium(III).
[0016] This invention designs a low-cost polymer emulsion system to synthesize polymer microspheres with a certain cross-linking structure, controls their swelling degree in rare earth complex solutions, and ensures the penetration and diffusion of rare earth complexes.
[0017] Preferably, the microspheres are any one of cross-linked polymethyl methacrylate microspheres, cross-linked polystyrene microspheres, or cross-linked copolymer microspheres of methyl methacrylate and styrene.
[0018] Preferably, the mass ratio of microspheres to rare earth complex is 1:(0.005-0.2).
[0019] Preferably, the ultrasound is performed at a frequency of 20–60 kHz for 1–3 hours.
[0020] More preferably, the ultrasound is performed at a frequency of 30-50 kHz for 1.5-2.5 hours.
[0021] Preferably, the oscillation is performed at a rotation speed of 30–70 r / min for 20–28 hours.
[0022] More preferably, the oscillation is performed at a rotational speed of 40–60 r / min for 22–26 hours.
[0023] Preferably, the centrifugation is performed at 8000–16000 r / min for 0.5–1.5 hours.
[0024] The rare earth complex photonic glass prepared by the above method should also be within the scope of protection of this invention.
[0025] This invention provides an inkjet-printed invisible photonic glass anti-counterfeiting ink, which is a solution containing the aforementioned rare earth complex photonic glass. Preferably, the solvent is deionized water.
[0026] Preferably, the mass-to-volume ratio of the rare earth complex photonic glass to water is (0.001 to 0.1):1.
[0027] More preferably, the mass-to-volume ratio of the rare earth complex photonic glass to water is 0.01:1.
[0028] The ink can emit fluorescence when excited by ultraviolet light (200-400nm).
[0029] The present invention also provides the application of the above-mentioned rare earth complex photonic glass or the above-mentioned inkjet printed invisible photonic glass anti-counterfeiting ink in the fields of information encryption, optical anti-counterfeiting or specific identification.
[0030] Furthermore, in the above-described embodiments of the present invention, the rare earth complexes: cerium(III) di[potassium hydrogen tris(3-phenyl-5-methylpyrazol-1-yl)borate], terbium(III) di[2-phenylpyridine], europium(III) tri[4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione], europium(III) tri[4,4,4-trifluoro-1-(2-furanyl)-1,3-butanedione], and dysprosium(III) di[terpyridine] are prepared by the following methods:
[0031] (1) The preparation method of cerium(III) di[potassium hydrogen tris(3-phenyl-5-methylpyrazol-1-yl)borate] is as follows:
[0032] The ligand potassium tri(3-phenyl-5-methylpyrazol-1-yl)borate (0.8–1.2 mmol) and cerium trichloride hexahydrate (0.3–0.7 mmol) were uniformly dispersed in a DMF-EtOH mixed solvent (28–32 mL, DMF to EtOH volume ratio 1:2). After heating, the reaction yielded colorless polyhedral crystals of di[potassium tri(3-phenyl-5-methylpyrazol-1-yl)borate]cerium(III).
[0033] Preferably, the heating reaction is carried out at 75–85°C for 40–56 hours.
[0034] Preferably, the product obtained after heating the reaction is allowed to cool naturally to room temperature, then repeatedly washed with DMF and dried.
[0035] (2) The preparation method of (bipyridine)bis[2-phenylpyridine]terbium(III) is as follows:
[0036] Bipyridine (0.8–1.2 mmol), 2-phenylpyridine (1.8–2.2 mmol), and terbium trichloride (0.8–1.2 mmol) were dissolved in 48–52 mL of ethanol, mixed thoroughly, and the pH was adjusted to 6–7. The mixture was then heated and the reaction proceeded. After cooling, a white precipitate was obtained. The white precipitate was ultrasonically centrifuged in 2–10 mL of ethanol and dried to obtain a white solid powder product (bipyridine)bis[2-phenylpyridine]terbium(III).
[0037] Preferably, the pH of the mixed solution is adjusted using concentrated ammonia.
[0038] Preferably, the heating reaction is carried out in a water bath at 50–70°C for 3–5 hours.
[0039] Preferably, the cooling is performed at room temperature for 40–56 hours.
[0040] Preferably, the number of centrifugation cycles is 2 to 5 (more preferably 3).
[0041] Preferably, the drying conditions are 70-90°C for 2-10 hours.
[0042] Preferably, the material is dried before being ground.
[0043] (3) The preparation method of (4,4-dibromo-bipyridine)tris[4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione]eup(III) is as follows:
[0044] ① In a mixed solution of 8–12 mL of ethanol and ammonia (volume ratio of ethanol to ammonia is 9:1), add 10–16 mmol of ligand 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione, seal and let stand, then add 8–12 mL of an ethanol solution of europium nitrate hexahydrate with a concentration of 0.1–0.2 g / mL and 8–12 mL of an ethanol solution of 4,4-dibromo-bipyridine with a concentration of 0.1–0.2 g / mL, stir overnight to obtain a mixture;
[0045] ② Adjust the pH of the above mixture to between 6 and 7, and dry the mixture to obtain a solid powder of (4,4-dibromo-bipyridine)tris[4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione]eupy(III).
[0046] Preferably, ammonia is used to adjust the pH of the mixture.
[0047] Preferably, the drying temperature is 40–50°C.
[0048] Preferably, the product is washed sequentially with ethanol and hexane before drying.
[0049] (4) The preparation method of (phenanthroline)tris[4,4,4-trifluoro-1-(2-furanyl)-1,3-butanedione]europium(III) is as follows:
[0050] ① Add 10–16 mmol of 4,4,4-trifluoro-1-(2-furanyl)-1,3-butanedione to a mixed solution of 8–12 mL of ethanol and ammonia (volume ratio of ethanol to ammonia is 9:1), seal and let stand. Then add 8–12 mL of ethanol solution of europium nitrate hexahydrate with a concentration of 0.1–0.2 g / mL and 8–12 mL of ethanol solution of 1,10-phenanthroline with a concentration of 0.05–0.1 g / mL, stir overnight to obtain a mixture;
[0051] ② Adjust the pH value of the above mixture to between 6 and 7, and dry the mixture to obtain solid powder of (phenanthroline)tris[4,4,4-trifluoro-1-(2-furanyl)-1,3-butanedione]europium(III).
[0052] Preferably, ammonia is used to adjust the pH of the mixture.
[0053] Preferably, the drying temperature is 40–50°C.
[0054] Preferably, the product is washed sequentially with ethanol and hexane before drying.
[0055] (5) The preparation method of bis[terpyridine]dysprosium(III) is as follows:
[0056] ① Dissolve 1.5–2.5 mmol of the ligand terpyridine in tetrahydrofuran to obtain a colorless and transparent solution. Add 2–12 mL (0.1 mmol / mL) of prepared dysprosium chloride ethanol solution while heating and stirring, and adjust the pH to 6–7 to obtain a white precipitate.
[0057] ②The resulting white precipitate was heated and stirred, then allowed to stand, filtered, washed, and dried to obtain a di[terpyridine]dysprosium(III) complex.
[0058] Preferably, ammonia is used to adjust the pH value.
[0059] Preferably, the heating and stirring conditions in step ② are stirring for 1.5 to 2.5 hours.
[0060] Preferably, the settling condition in step ② is 13 to 17 hours.
[0061] Preferably, in step ②, anhydrous ethanol is used for washing.
[0062] The present invention has the following beneficial effects:
[0063] This invention utilizes the principle that rare earth complexes have no absorption in the visible light region and the stable, water-resistant, colorless, clearly layered, weather-resistant, and easily controllable viscosity properties of polymer microspheres. Furthermore, the polymer microspheres form a photonic glass structure after inkjet printing, thus constructing an inkjet-printed invisible photonic glass anti-counterfeiting ink that enables the ink system to achieve special anti-counterfeiting functions.
[0064] The method for preparing inkjet-printed invisible photonic glass anti-counterfeiting ink of this invention is simple and convenient to operate. It utilizes solid-phase extraction to improve the production efficiency and product quality of rare-earth complex photonic glass, requires no additional chemical modification, uses inexpensive and readily available raw materials, requires no expensive equipment, and is low-cost, suitable for industrial production, and applicable to various uses, thus possessing significant practical application value. Furthermore, the inkjet-printed invisible photonic glass anti-counterfeiting ink of this invention uses water as a solvent, eliminating volatile organic compound pollution. Attached Figure Description
[0065] Figure 1The fluorescence spectrum of the blue invisible anti-counterfeiting ink prepared in Example 1 under 330nm ultraviolet light excitation.
[0066] Figure 2 The fluorescence spectrum of the yellow invisible anti-counterfeiting ink prepared in Example 2 under 365nm ultraviolet light excitation.
[0067] Figure 3 The fluorescence spectrum of the red invisible anti-counterfeiting ink prepared in Example 3 under 365nm ultraviolet light excitation.
[0068] Figure 4 The inks prepared in Examples 1, 2, and 4 are used to print latent fluorescent anti-counterfeiting patterns on doring paper (white background). The top image is under visible light, and the bottom image is under a 365nm ultraviolet lamp; from left to right, they correspond to Examples 1, 2, and 4.
[0069] Figure 5 The inks prepared in Examples 1, 2, and 4 are used to print composite anti-counterfeiting patterns of structural color and fluorescence on black cardstock (dark background). The left image shows the structural color under visible light, and the right image shows the fluorescent anti-counterfeiting color under a 365nm ultraviolet lamp; from bottom to top, they correspond to Examples 1, 2, and 4.
[0070] Figure 6 The image shows a scanning electron microscope image of a photonic glass structure formed by printing the ink prepared in Example 5 onto doling paper. Detailed Implementation
[0071] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.
[0072] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.
[0073] In the examples, DMF refers to N,N-dimethylformamide, and EtOH refers to ethanol.
[0074] Example 1
[0075] I. Preparation of aqueous rare earth complex photonic glasses
[0076] 1. Preparation of rare earth complexes
[0077] The ligand potassium hydrogen tris(3-phenyl-5-methylpyrazole-1-yl)borate (1 mmol, 522 mg) and cerium trichloride hexahydrate (0.5 mmol, 132 mg) were uniformly dispersed in a DMF-EtOH mixed solvent (30 mL, DMF to EtOH volume ratio 1:2). The mixture was added to a glass sample tube and reacted in a 100 mL reaction vessel at 80 °C for 48 h. After natural cooling to room temperature, the resulting solid was repeatedly washed with DMF and dried to obtain colorless polyhedral crystals of di[potassium hydrogen tris(3-phenyl-5-methylpyrazole-1-yl)borate]cerium(III).
[0078] 2. Preparation of microspheres
[0079] The preparation method of the microspheres in this embodiment includes the following steps: 85 mL of deionized water, 10 mL of styrene, 0.35 mL of α-methacrylic acid, 3 mL of 1% wt sodium dodecyl sulfonate aqueous solution, and 0.2 mL of divinylbenzene are added to a round-bottom flask. The mixture is magnetically stirred and heated to 78°C. 2 mL of 50 mg / mL potassium persulfate aqueous solution is added, and the reaction is allowed to proceed for 12 hours. After the reaction is complete, 50 mL of ethanol is added, and the mixture is centrifuged at 12000 r / min for 60 minutes. 1 g of the resulting solid is then added to 10 mL of deionized water and ultrasonically dispersed to obtain a submicron-sized cross-linked polystyrene microsphere emulsion.
[0080] 3. Preparation of aqueous rare earth complex photonic glasses
[0081] Cerium(III) di[potassium hydrogen tris(3-phenyl-5-methylpyrazol-1-yl)borate] was dissolved in ethanol to prepare a 2 mg / mL rare earth complex solution. The aforementioned cross-linked polystyrene microsphere emulsion was added to the rare earth complex solution (volume ratio of rare earth complex solution to microsphere emulsion was 2:8) under shaking (50 r / min). The mixture was sonicated (40 kHz) for 2 hours and then shaken (50 r / min) for 24 hours. The rare earth complex was spontaneously incorporated into the microspheres via solid-phase extraction. After shaking, the mixture was centrifuged at 12000 r / min for 1 hour to obtain an aqueous rare earth complex photonic glass.
[0082] II. Preparation of Water-Based Rare Earth Complex Invisible Fluorescent Ink (i.e., Invisible Photonic Glass Anti-counterfeiting Ink)
[0083] The prepared aqueous rare earth complex photonic glass is ultrasonically dispersed (at a frequency of 40 kHz) in deionized water. The mass ratio of the aqueous rare earth complex photonic glass to water is 1:100, which yields the corresponding inkjet-printed invisible photonic glass anti-counterfeiting ink.
[0084] The emission spectrum of this ink under 330nm ultraviolet light excitation is as follows: Figure 1 As shown, it displays a bright blue light.
[0085] III. Inkjet Printing
[0086] When this ink is added to the ink cartridge and inkjet printed on doling paper (light-colored background), the resulting text is invisible under visible light (e.g., Figure 4 (Top left), exhibits bright blue light under 365nm ultraviolet light excitation (e.g.) Figure 4 (Bottom left). After adding this ink to the cartridge, inkjet printing on black cardstock (dark background) produces text that displays structural colors (e.g., ...) under visible light. Figure 5 (Lower left), exhibiting bright blue light under 365nm ultraviolet light excitation (e.g.) Figure 5 (Bottom right)
[0087] Example 2
[0088] I. Preparation of aqueous rare earth complex photonic glasses
[0089] 1. Preparation of rare earth complexes
[0090] 2,2'-Bipyridine (1 mmol, 156 mg), 2-phenylpyridine (2 mmol, 310 mg), and terbium trichloride (1 mmol, 265 mg) were dissolved in 50 mL of ethanol, mixed thoroughly, and the pH of the mixture was adjusted to 6–7 with concentrated ammonia. The mixture was heated in a water bath to 60 °C and reacted for 4 hours, then cooled at room temperature for 48 hours to obtain a white precipitate. The white precipitate was ultrasonically centrifuged three times in 5 mL of ethanol to remove unreacted monomers, and then vacuum dried in an oven at 80 °C for 6 hours. The precipitate was then ground to obtain a white solid powder product (bipyridine)bis[2-phenylpyridine]terbium(III).
[0091] 2. Preparation of microspheres
[0092] The preparation method of the microspheres in this embodiment includes the following steps: 85 mL of deionized water, 10 mL of styrene, 0.35 mL of α-methacrylic acid, 3 mL of 1% wt sodium dodecyl sulfonate aqueous solution, and 0.2 mL of divinylbenzene are added to a round-bottom flask. The mixture is magnetically stirred and heated to 78°C. 2 mL of 50 mg / mL potassium persulfate aqueous solution is added, and the reaction is allowed to proceed for 12 hours. After the reaction is complete, 50 mL of ethanol is added, and the mixture is centrifuged at 12000 r / min for 60 minutes. 1 g of the resulting solid is then added to 10 mL of deionized water and ultrasonically dispersed to obtain a submicron-sized cross-linked polystyrene microsphere emulsion.
[0093] 3. Preparation of aqueous rare earth complex photonic glasses
[0094] Terbium(III) (bipyridine)bis[2-phenylpyridine] was dissolved in ethanol to prepare a 10 mg / mL rare earth complex solution. The aforementioned cross-linked polystyrene microsphere emulsion was added to the rare earth complex solution (volume ratio of rare earth complex solution to microsphere emulsion was 2:8) under shaking (50 r / min). The mixture was sonicated (40 kHz) for 2 hours and then shaken (50 r / min) for 24 hours. The rare earth complex was spontaneously incorporated into the microspheres via solid-phase extraction. After shaking, the mixture was centrifuged at 12000 r / min for 1 hour to obtain an aqueous rare earth complex photonic glass.
[0095] II. Preparation of Water-Based Rare Earth Complex Invisible Fluorescent Ink (i.e., Invisible Photonic Glass Anti-counterfeiting Ink)
[0096] The prepared aqueous rare earth complex photonic glass is ultrasonically dispersed (at a frequency of 40 kHz) in deionized water. The mass ratio of the aqueous rare earth complex photonic glass to water is 1:100, which yields the corresponding inkjet-printed invisible photonic glass anti-counterfeiting ink.
[0097] The emission spectrum of this ink under 365nm ultraviolet light excitation is as follows: Figure 2 As shown, it displays a bright yellow-green light.
[0098] III. Inkjet Printing
[0099] When this ink is added to the ink cartridge and inkjet printed on doling paper (light-colored background), the resulting text is invisible under visible light (e.g., Figure 4 (Above and below), under 365nm ultraviolet light excitation, it exhibits a bright yellow-green light (e.g., Figure 4 (Lower middle). After adding this ink to the cartridge, inkjet printing on black cardstock (dark background) produces text that displays structural colors (e.g., ...) under visible light. Figure 5 (Left center), exhibiting a bright yellow-green light under 365nm ultraviolet light excitation (e.g.) Figure 5 (Right center).
[0100] Example 3
[0101] I. Preparation of aqueous rare earth complex photonic glasses
[0102] 1. Preparation of rare earth complexes
[0103] To a 10 mL mixture of ethanol and ammonia (9:1 volume ratio), add 2.87 g (13 mmol) of the ligand 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione. Seal and allow to stand until the ammonia odor disappears, yielding an ammonium salt solution of 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione. Then, add 10 mL of an ethanol solution of europium nitrate hexahydrate (0.164 g / mL) and 10 mL of an ethanol solution of 4,4-dibromo-bipyridine (0.135 g / mL) to the ammonium salt solution of 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione. Stir overnight at room temperature to obtain a mixture. Add a small amount of ammonia to the mixture to maintain the pH between 6 and 7. Place the mixture in a 40°C oven to allow the solvent to evaporate slowly. The solid powder of (4,4-dibromo-bipyridine)tri[4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione]europium(III) can be obtained by washing with 40 mL of ethanol and 40 mL of hexane in sequence and then drying.
[0104] 2. Preparation of microspheres
[0105] The preparation method of the microspheres in this embodiment includes the following steps: 85 mL of deionized water, 10 mL of methyl methacrylate, 0.35 mL of α-methacrylic acid, 5 mL of 1% wt sodium dodecyl sulfonate aqueous solution, and 0.5 mL of ethylene glycol diacrylate are added to a round-bottom flask. The mixture is magnetically stirred and heated to 78°C. 2 mL of 50 mg / mL potassium persulfate aqueous solution is added, and the reaction is allowed to proceed for 12 hours. After the reaction is complete, 50 mL of ethanol is added, and the mixture is centrifuged at 12000 r / min for 60 minutes. 1 g of the resulting solid is then added to 10 mL of deionized water and ultrasonically dispersed to obtain a submicron-sized cross-linked polymethyl methacrylate microsphere emulsion.
[0106] 3. Preparation of aqueous rare earth complex photonic glasses
[0107] Europium(III) (4,4-dibromo-bipyridine)tris[4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione]europium(III) was dissolved in ethanol to prepare a 30 mg / mL rare earth complex solution. The aforementioned cross-linked polymethyl methacrylate microsphere emulsion was added to the rare earth complex solution (volume ratio of rare earth complex solution to microsphere emulsion was 2:8) under shaking (50 rpm). The mixture was then sonicated (30 kHz) for 2.5 hours and shaken (40 rpm) for 26 hours. The rare earth complex was spontaneously incorporated into the microspheres via solid-phase extraction. After shaking, the mixture was centrifuged at 8000 rpm for 1.5 hours to obtain an aqueous rare earth complex photonic glass.
[0108] II. Preparation of Water-Based Rare Earth Complex Invisible Fluorescent Ink (i.e., Invisible Photonic Glass Anti-counterfeiting Ink)
[0109] The prepared aqueous rare earth complex photonic glass is ultrasonically dispersed (at a frequency of 40 kHz) in deionized water. The mass ratio of the aqueous rare earth complex photonic glass to water is 1:10, which yields the corresponding inkjet-printed invisible photonic glass anti-counterfeiting ink.
[0110] The emission spectrum of this ink under 365nm ultraviolet light excitation is as follows: Figure 3 As shown, it displays a bright red light.
[0111] Example 4
[0112] I. Preparation of aqueous rare earth complex photonic glasses
[0113] 1. Preparation of rare earth complexes
[0114] To a 9:1 volume ratio of ethanol and ammonia, 2.67 g (13 mmol) of 4,4,4-trifluoro-1-(2-furanyl)-1,3-butanedione was added. The mixture was sealed and allowed to stand until the ammonia odor disappeared, yielding an ammonium salt solution of 4,4,4-trifluoro-1-(2-furanyl)-1,3-butanedione. Then, 10 mL of a 0.164 g / mL ethanol solution of europium nitrate hexahydrate and 10 mL of a 0.078 g / mL ethanol solution of 1,10-phenanthroline were added to the ammonium salt solution of 4,4,4-trifluoro-1-(2-furanyl)-1,3-butanedione. The mixture was stirred overnight at room temperature to obtain a final mixture. A small amount of ammonia was added to the mixture to maintain the pH between 6 and 7. The mixture was then placed in a 40°C oven to allow the solvent to evaporate slowly. The solid powder of (phenanthroline)tri[4,4,4-trifluoro-1-(2-furanyl)-1,3-butanedione]europium(III) can be obtained by washing with 40 mL of ethanol and 40 mL of hexane in sequence and then drying.
[0115] 2. Preparation of microspheres
[0116] The preparation method of the microspheres in this embodiment includes the following steps: 85 mL of deionized water, 10 mL of styrene, 0.35 mL of α-methacrylic acid, 5 mL of 1% wt sodium dodecyl sulfonate aqueous solution, and 0.2 mL of divinylbenzene are added to a round-bottom flask. The mixture is magnetically stirred and heated to 78°C. 2 mL of 50 mg / mL potassium persulfate aqueous solution is added, and the reaction is allowed to proceed for 12 hours. After the reaction is complete, 50 mL of ethanol is added, and the mixture is centrifuged at 12000 r / min for 60 minutes. The resulting solid is then dispersed by ultrasonication with deionized water to obtain a submicron-sized cross-linked polystyrene microsphere emulsion.
[0117] 3. Preparation of aqueous rare earth complex photonic glasses
[0118] Europium(III) (phenanthroline)tris[4,4,4-trifluoro-1-(2-furanyl)-1,3-butanedione] was dissolved in ethanol to prepare a 50 mg / mL rare earth complex solution. The cross-linked polystyrene microsphere emulsion described above was added to the rare earth complex solution (volume ratio of rare earth complex solution to microsphere emulsion was 2:8) under shaking (50 rpm). The mixture was then sonicated (50 kHz) for 1.5 hours and shaken (60 rpm) for 22 hours. The rare earth complex was spontaneously incorporated into the microspheres via solid-phase extraction. After shaking, the mixture was centrifuged at 16000 rpm for 0.5 hours to obtain an aqueous rare earth complex photonic glass.
[0119] II. Preparation of Water-Based Rare Earth Complex Invisible Fluorescent Ink (i.e., Invisible Photonic Glass Anti-counterfeiting Ink)
[0120] The prepared aqueous rare earth complex photonic glass is ultrasonically dispersed (at a frequency of 40 kHz) in deionized water. The mass ratio of the aqueous rare earth complex photonic glass to water is 1:1000, which yields the corresponding inkjet-printed invisible photonic glass anti-counterfeiting ink.
[0121] III. Inkjet Printing
[0122] When this ink is added to the ink cartridge and inkjet printed on doling paper (light-colored background), the resulting text is invisible under visible light (e.g., Figure 4 (Top right), exhibits bright red light under 365nm ultraviolet light excitation (e.g.) Figure 4 (Bottom right). After adding this ink to the cartridge, inkjet printing on black cardstock (dark background) produces text that displays structural colors (e.g., ...) under visible light. Figure 5 (Top left), exhibits bright blue light under 365nm ultraviolet light excitation (e.g.) Figure 5 (Top right)
[0123] Example 5
[0124] I. Preparation of aqueous rare earth complex photonic glasses
[0125] 1. Preparation of rare earth complexes
[0126] 466 mg (2 mmol) of ligand terpyridine was dissolved in tetrahydrofuran to obtain a colorless and transparent solution. 10 mL (0.1 mmol / mL) of dysprosium chloride ethanol solution was added under heating and stirring. The pH was adjusted to 6-7 with ammonia water, resulting in a white precipitate. The solution was heated and stirred for 2 hours, allowed to stand for 15 hours, filtered, washed with anhydrous ethanol, and dried to obtain the di[terpyridine]dysprosium(III) complex.
[0127] 2. Preparation of microspheres
[0128] The preparation method of the microspheres in this embodiment is the same as that of the microspheres in Example 1.
[0129] 3. Preparation of aqueous rare earth complex photonic glasses
[0130] Di[terpyridine]dysprosium(III) was dissolved in ethanol to prepare an 80 mg / mL rare earth complex solution. The aforementioned cross-linked polystyrene microsphere emulsion was added to the rare earth complex solution (volume ratio of rare earth complex solution to microsphere emulsion was 2:8) under shaking (50 r / min). The mixture was sonicated (40 kHz) for 2 hours and then shaken (50 r / min) for 24 hours. The rare earth complex was spontaneously incorporated into the microspheres via solid-phase extraction. After shaking, the mixture was centrifuged at 12000 r / min for 1 hour to obtain an aqueous rare earth complex photonic glass.
[0131] II. Preparation of Water-Based Rare Earth Complex Invisible Fluorescent Ink (i.e., Invisible Photonic Glass Anti-counterfeiting Ink)
[0132] The prepared aqueous rare earth complex photonic glass is ultrasonically dispersed (at a frequency of 40 kHz) in deionized water. The mass ratio of the aqueous rare earth complex photonic glass to water is 1:100, which yields the corresponding inkjet-printed invisible photonic glass anti-counterfeiting ink.
[0133] The photonic glass obtained by printing on doling paper using this ink is shown in a scanning electron microscope image. Figure 6 As shown in the figure, the microspheres exhibit a near-monodisperse particle size and are arranged randomly, which is consistent with the characteristics of photonic glass.
[0134] Comparative Example 1
[0135] The preparation method of the aqueous rare earth complex photonic glass in Comparative Example 1 differs from that in Example 1 in that the rare earth complex di[potassium hydrogen tris(3-phenyl-5-methylpyrazol-1-yl)borate]cerium(III) is replaced with tri[acetylacetone]europium(III).
[0136] The specific method is as follows:
[0137] I. Preparation of aqueous rare earth complex photonic glasses
[0138] 1. Preparation of rare earth complexes
[0139] The rare earth complex tri[acetylacetone]europium(III) in this comparative example was commercially available.
[0140] 2. Preparation of microspheres
[0141] In a round-bottom flask, add 85 mL of deionized water, 10 mL of styrene, 0.35 mL of α-methacrylic acid, 3 mL of 1% wt sodium dodecyl sulfonate aqueous solution, and 0.2 mL of divinylbenzene. Stir magnetically and heat to 78 °C. Add 2 mL of 50 mg / mL potassium persulfate aqueous solution and react for 12 hours. After the reaction is complete, add 50 mL of ethanol, centrifuge at 12000 r / min for 60 minutes, and take 1 g of the obtained solid. Add 10 mL of deionized water and ultrasonically disperse to obtain submicron-sized cross-linked polystyrene microsphere emulsion.
[0142] 3. Preparation of aqueous rare earth complex photonic glasses
[0143] Commercially available tri[acetylacetone] europium(III) was dissolved in ethanol to prepare a 1 mg / mL rare earth complex solution. The above-mentioned cross-linked polystyrene microsphere emulsion was added to the rare earth complex solution under shaking (50 r / min) (the volume ratio of rare earth complex solution to microsphere emulsion was 2:8). The mixture was sonicated (40 kHz) for 2 hours and shaken (50 r / min) for 24 hours. After shaking, the mixture was centrifuged at 12000 r / min for 1 hour to obtain an aqueous rare earth complex photonic glass.
[0144] II. Preparation of Water-Based Rare Earth Complex Invisible Fluorescent Ink (i.e., Invisible Photonic Glass Anti-counterfeiting Ink)
[0145] The prepared aqueous rare earth complex photonic glass was ultrasonically dispersed (at a frequency of 40 kHz) in deionized water at a mass ratio of 1:100 to obtain the corresponding ink.
[0146] The resulting ink showed no obvious fluorescence under ultraviolet light (150nm-400nm) excitation, which is because the rare earth complex and microspheres could not achieve solid-phase extraction driven by polarity.
[0147] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. A method for preparing an inkjet-printable water-based rare-earth complex photonic glass, characterized in that, Microspheres were added to a rare earth complex solution and subjected to ultrasonication, vibration, and centrifugation to obtain the aqueous rare earth complex photonic glass. The rare earth complex is any one of the following: cerium(III) di[potassium hydrogen tris(3-phenyl-5-methylpyrazol-1-yl)borate], terbium(III) di[2-phenylpyridine], europium(III) tri[4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione], europium(III) tri[4,4,4-trifluoro-1-(2-furanyl)-1,3-butanedione], and dysprosium(III) di[terpyridine]; the mass ratio of microspheres to rare earth complex is 1:(0.005-0.2). The microspheres are submicron-sized polymer microspheres with cross-linked structures.
2. The preparation method according to claim 1, characterized in that, The ultrasound is performed at a frequency of 20-60 kHz for 1-3 hours.
3. The preparation method according to claim 1, characterized in that, The oscillation is performed at a rotation speed of 30~70 r / min for 20~28 hours.
4. The aqueous rare earth complex photonic glass prepared by any of the preparation methods described in claims 1 to 3.
5. A water-based rare-earth complex invisible fluorescent ink suitable for inkjet printing, characterized in that, It is a solution containing the aqueous rare earth complex photonic glass as described in claim 4.
6. The aqueous rare earth complex stealth fluorescent ink according to claim 5, characterized in that, The solvent is water, and the mass-to-volume ratio of the aqueous rare earth complex photonic glass to water is (0.001~0.1):
1.
7. The application of the aqueous rare earth complex photonic glass of claim 4 or the aqueous rare earth complex invisible fluorescent ink of claim 5 in the fields of information encryption or specific identification.
8. The application according to claim 7, characterized in that, The specific identification includes optical anti-counterfeiting.