An organic long-afterglow material, a preparation method and application thereof

Abstract

The application relates to the technical field of materials, and discloses an organic long-afterglow material and a preparation method and application thereof. The organic long-afterglow material comprises a host component and guest molecules doped in the host component; the host component comprises melamine formaldehyde resin; the guest molecules comprise aromatic organic compounds containing heteroatoms; the heteroatoms comprise N and S. The melamine formaldehyde resin organic long-afterglow material provided by the application is doped with aromatic organic compounds containing heteroatoms N and S, has long afterglow light-emitting life, good long-afterglow performance stability, and a maximum emission peak life in a time spectrum of more than 100 ms, and can meet the performance requirements of long-afterglow materials in the fields of anti-counterfeiting, data encryption, functional ink, road marking and the like.

Description

Technical Field

[0001] This invention relates to the field of materials technology, and in particular to an organic long afterglow material, its preparation method, and its application. Background Technology

[0002] Long-afterglow materials can continue to emit light after the excitation source stops. This characteristic allows them to effectively eliminate the influence of transient background light, thus significantly improving the clarity and recognizability of the emitted signal. Therefore, these materials have broad application prospects in fields such as anti-counterfeiting technology, emergency indication, intelligent transportation systems, bio-imaging technology, and data encryption. Traditionally, long-afterglow materials are mainly composed of inorganic components. Although they possess excellent properties, their preparation process typically requires high temperatures and has high production costs. More importantly, they contain heavy metal elements such as rare earth metals or transition metals, which to some extent limits their development and application. In contrast, organic materials are simpler to synthesize and modify, have lower costs, can be made flexible, and, importantly, have a smaller environmental impact.

[0003] Organic long-afterglow luminescence at room temperature is mainly achieved through the following methods: (1) providing a stable rigid structural environment for organic molecules through crystal engineering and forming a special molecular aggregation morphology; (2) polymerizing organic molecules into polymer materials; (3) incorporating organic molecules into a solid matrix that can isolate oxygen and restrict molecular movement using the host-guest doping method. Among these methods, the method of doping organic molecules (guests) into a polymer matrix (host) is more advantageous because it is simpler and faster, and the long-afterglow luminescence performance of the material can be controlled by changing parameters such as the chemical structure and doping concentration of organic molecules and the molecular weight of the polymer matrix. At the same time, organic long-afterglow materials prepared by this method also have advantages such as good processing performance, flexibility, and ease of large-area production. However, since most of the matrices used are linear polymers with polar side groups, such as polylactic acid (PLA), polyvinyl alcohol (PVA), and polymethyl methacrylate (PMMA), the long-afterglow performance of the materials is greatly affected by water vapor and oxygen in the air, resulting in poor stability. These problems seriously restrict the practical application of polymer-based organic long-afterglow materials. Summary of the Invention

[0004] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, one objective of the present invention is to provide an organic long afterglow material; a second objective is to provide a method for preparing such an organic long afterglow material; and a third objective is to provide an anti-counterfeiting material.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A first aspect of the present invention provides an organic long afterglow material comprising a host component and guest molecules doped in the host component;

[0007] The main component includes melamine-formaldehyde resin;

[0008] The guest molecules include aromatic organic compounds containing heteroatoms;

[0009] The heteroatoms include N and S.

[0010] Preferably, the heteroatom-containing aromatic organic compound comprises at least one of formulas (I) to (V):

[0011]

[0012] Preferably, the mass fraction of guest molecules in the organic long afterglow material is 0.05-0.5%; more preferably, the mass fraction of guest molecules in the organic long afterglow material is 0.1-0.3%.

[0013] Preferably, the organic long afterglow material is spherical; specifically, the organic long afterglow material is a polymer microsphere material.

[0014] Preferably, the particle size of the organic long afterglow material is 2-8 μm; more preferably, the particle size of the organic long afterglow material is 2-5 μm.

[0015] A second aspect of the present invention provides a method for preparing the organic long afterglow material described in the first aspect of the present invention, comprising the following steps:

[0016] 1) Mix an aromatic organic compound containing heteroatoms with an organic solvent to obtain solution A;

[0017] 2) Mix melamine and formaldehyde aqueous solution, add alkali to adjust the pH value, heat the reaction to obtain solution B;

[0018] 3) Mix solution A with solution B, then mix with emulsifier, add acid to adjust pH value, react to obtain polymer emulsion;

[0019] 4) The polymer emulsion is centrifuged, washed, and dried to obtain the organic long afterglow material.

[0020] Preferably, in step 1), the solid-liquid ratio of the heteroatom-containing aromatic organic compound to the organic solvent is (8-15) mg:1 mL; more preferably, the solid-liquid ratio of the heteroatom-containing aromatic organic compound to the organic solvent is (8-10) mg:1 mL.

[0021] Preferably, in step 1), the organic solvent includes one of methanol, ethanol, acetone, dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran, and acetonitrile; more preferably, the organic solvent is tetrahydrofuran.

[0022] Preferably, in step 2), the molar ratio of melamine to formaldehyde is 1:(1-5); more preferably, the molar ratio of melamine to formaldehyde is 1:(2-3).

[0023] Preferably, in step 2), the solid-liquid ratio of melamine to formaldehyde aqueous solution is 1g:(1-2)mL; more preferably, the solid-liquid ratio of melamine to formaldehyde aqueous solution is 1g:(1-1.3)mL.

[0024] Preferably, in step 2), the concentration of the formaldehyde aqueous solution is 1-55 wt%; more preferably, the concentration of the formaldehyde aqueous solution is 30-40 wt%.

[0025] Preferably, in step 2), the alkali includes one of an amine, an alkali metal hydroxide, and an alkali metal carbonate; more preferably, the alkali includes one of diethylamine, triethylamine, triethanolamine, sodium hydroxide, potassium hydroxide, and sodium carbonate; even more preferably, the alkali is triethanolamine.

[0026] Preferably, in step 2), the temperature of the heating reaction is 80–110°C; more preferably, the temperature of the heating reaction is 90–100°C.

[0027] Preferably, in step 2), the heating reaction time is 5 to 20 minutes; more preferably, the heating reaction time is 5 to 10 minutes.

[0028] Preferably, in step 2), the pH value of solution B is 7-11; more preferably, the pH value of solution B is 8-9.

[0029] Preferably, in step 3), the volume ratio of solution A, solution B and emulsifier is 1:(5-10):(50-150); more preferably, the volume ratio of solution A, solution B and emulsifier is 1:(5-8):(80-120).

[0030] Preferably, in step 3), the concentration of the emulsifier is 2-15 mg / mL; more preferably, the concentration of the emulsifier is 2-10 mg / mL.

[0031] Preferably, in step 3), the emulsifier includes at least one of polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA).

[0032] Preferably, in step 3), the acid includes one of acetic acid, oxalic acid, hydrochloric acid, and sulfuric acid; more preferably, the acid is acetic acid.

[0033] Preferably, in step 3), the reaction temperature is 40–70°C; more preferably, the reaction temperature is 50–60°C.

[0034] Preferably, in step 3), the reaction time is 15 to 40 minutes; more preferably, the reaction time is 20 to 30 minutes.

[0035] Preferably, in step 3), the reaction process is aided by stirring; the stirring speed is 500-800 r / min.

[0036] Preferably, in step 3), the pH value of the polymer emulsion is 4 to 6; more preferably, the pH value of the polymer emulsion is 5 to 6.

[0037] Preferably, in step 4), the centrifugation speed is 3000-8000 r / min; more preferably, the centrifugation speed is 5000-8000 r / min.

[0038] Preferably, in step 4), the centrifugation time is 5 to 15 minutes; more preferably, the centrifugation time is 5 to 10 minutes.

[0039] Preferably, in step 4), the reagent used for washing includes deionized water; the number of washing cycles is 3 to 4.

[0040] Preferably, in step 4), the drying temperature is 40–60°C; more preferably, the drying temperature is 45–55°C.

[0041] Preferably, in step 4), the drying time is 20-30 hours; more preferably, the drying time is 20-25 hours.

[0042] A third aspect of the present invention provides an anti-counterfeiting material comprising the organic long afterglow material described in the first aspect of the present invention; the anti-counterfeiting material further comprises a polymer; the mass ratio of the organic long afterglow material to the polymer is 1:(15-20); more preferably, the mass ratio of the organic long afterglow material to the polymer is 1:(19-20).

[0043] Preferably, the polymer comprises ethylene-vinyl acetate copolymer (EVA).

[0044] Preferably, the method for preparing the anti-counterfeiting material includes the following steps:

[0045] The organic long afterglow material is mixed with an organic solvent, and then mixed with an organic solution of ethylene-vinyl acetate copolymer. The solvent is then heated to evaporate, thus obtaining the anti-counterfeiting material.

[0046] Preferably, the solid-liquid ratio of the organic long afterglow material to the organic solvent is (40-60) mg:1 mL; more preferably, the solid-liquid ratio of the organic long afterglow material to the organic solvent is (45-55) mg:1 mL.

[0047] Preferably, the solid-liquid ratio of the ethylene-vinyl acetate copolymer to the organic solvent is 1 g:(5-10) mL; more preferably, the solid-liquid ratio of the ethylene-vinyl acetate copolymer to the organic solvent is 1 g:(5-7) mL.

[0048] Preferably, the organic solvent includes ethyl acetate.

[0049] Compared with the prior art, the beneficial effects of the present invention are:

[0050] 1) The melamine-formaldehyde resin organic long-afterglow material doped with aromatic organic compounds containing heteroatoms N and S provided by this invention has a long afterglow luminescence lifetime and good long-afterglow performance stability. The lifetime of the maximum emission peak in the delayed spectrum can reach more than 100ms, which can meet the performance requirements of long-afterglow materials in fields such as anti-counterfeiting, data encryption, functional inks, and road marking.

[0051] 2) The preparation method of organic long afterglow material provided by the present invention is simple. By changing the type and content of emulsifier used in emulsion polymerization, the particle size of melamine-formaldehyde resin microsphere afterglow material can be controlled to obtain polymer microsphere afterglow material with uniform particle size.

[0052] 3) The anti-counterfeiting material provided by this invention can produce a bright green afterglow after activation by ultraviolet light, which can meet the product's requirements for anti-counterfeiting and authenticity identification. The preparation method is simple and highly practical. Attached Figure Description

[0053] Figure 1 The 1H NMR spectrum of compound (Ⅰ) in Example 1 of this invention;

[0054] Figure 2 The 1H NMR spectrum of compound (II) in Example 2 of this invention;

[0055] Figure 3 The 1H NMR spectrum of compound (III) in Example 3 of this invention;

[0056] Figure 4 The 1H NMR spectrum of compound (Ⅳ) in Example 4 of this invention;

[0057] Figure 5 The 1H NMR spectrum of compound (V) in Example 5 of this invention;

[0058] Figure 6 The steady-state emission spectra of the solid powders of compounds of formulas (Ⅰ) to (Ⅴ) in Examples 1 to 5 of this invention are shown.

[0059] Figure 7 The graphs show the luminescence decay curves of the solid powders of compounds (Ⅰ) to (Ⅴ) in Examples 1 to 5 of this invention.

[0060] Figure 8 This is a scanning electron microscope image of the organic long afterglow material in Example 1 of the present invention;

[0061] Figure 9 This is a scanning electron microscope image of the organic long afterglow material in Example 6 of the present invention;

[0062] Figure 10 This is a scanning electron microscope image of the organic long afterglow material in Example 7 of the present invention;

[0063] Figure 11 This is a scanning electron microscope image of the organic long afterglow material in Example 8 of the present invention;

[0064] Figure 12 This is a scanning electron microscope image of the organic long afterglow material in Example 9 of the present invention;

[0065] Figure 13 The steady-state emission spectrum and afterglow emission spectrum of the organic long afterglow material in Example 1 of this invention are shown.

[0066] Figure 14 The steady-state emission spectrum and afterglow emission spectrum of the organic long afterglow material in Example 2 of this invention are shown.

[0067] Figure 15 The steady-state emission spectrum and afterglow emission spectrum of the organic long afterglow material in Example 3 of this invention are shown.

[0068] Figure 16 The steady-state emission spectrum and afterglow emission spectrum of the organic long afterglow material in Example 4 of this invention are shown.

[0069] Figure 17 The steady-state emission spectrum and afterglow emission spectrum of the organic long afterglow material in Example 5 of this invention are shown.

[0070] Figure 18 The graphs show the afterglow decay curves of the organic long afterglow materials in Examples 1-5 of this invention.

[0071] Figure 19These are images showing the afterglow luminescence phenomena of the organic long afterglow materials in Examples 1-5 of this invention;

[0072] Figure 20 This is a diagram illustrating the application of the anti-counterfeiting material in Embodiment 10 of the present invention. Detailed Implementation

[0073] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments can be obtained from conventional commercial sources or by existing technical methods. Unless otherwise specified, the experimental or testing methods are conventional methods in the art.

[0074] Compound (I) was purchased from Bid Pharmaceuticals, catalog number BD01103074, and was directly used in the preparation of organic long-afterglow materials in Examples 1 and 6-9; compounds (II) to (V) were synthesized based on compound (I) and were used in the preparation of organic long-afterglow materials in Examples 2-5, respectively. Wherein:

[0075] The method for synthesizing compound (II) is as follows:

[0076] Under an argon atmosphere, compound (I) 5H-benzo[a]benzo[4,5]thieno[3,2-c]carbazole (0.20 g, 0.62 mmol) and sodium tert-butoxide (0.24 g, 2.48 mmol) of formula (I) were added sequentially to 20 mL of ultra-dry tetrahydrofuran. After stirring at room temperature for 30 min, 1.00 mL of iodomethane was added, and the reaction was stopped after reflux for 12 h. After the reaction solution cooled to room temperature, the solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by silica gel column chromatography using a dichloromethane / petroleum ether (v / v, 2:1) mixture as the developing solvent, and then reprecipitated in a dichloromethane / n-hexane system to obtain a white powder (yield 91.2%).

[0077] The synthetic route for compound (II) is shown below:

[0078]

[0079] The method for synthesizing compound (III) is as follows:

[0080] Under an argon atmosphere, compound (I) 5H-benzo[a]benzo[4,5]thieno[3,2-c]carbazole (0.20 g, 0.62 mmol) and sodium hydride (0.59 g, 2.48 mmol) of formula (I) were added sequentially to 20 mL of ultra-dry tetrahydrofuran. After stirring at room temperature for 30 min, 1.00 mL of bromoethane was added, and the reaction was stopped after reflux for 12 h. After the reaction solution cooled to room temperature, the solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by silica gel column chromatography using a dichloromethane / petroleum ether (v / v, 2:1) mixture as the developing solvent, and then reprecipitated in a dichloromethane / n-hexane system to obtain a white powder (yield 83.7%).

[0081] The synthetic route for compound (III) is shown below:

[0082]

[0083] The method for synthesizing compound (Ⅳ) is as follows:

[0084] Under an argon atmosphere, compound (I) 5H-benzo[a]benzo[4,5]thieno[3,2-c]carbazole (0.20 g, 0.62 mmol) and sodium hydride (0.59 g, 2.48 mmol) of formula (I) were added sequentially to 20 mL of ultra-dry tetrahydrofuran. After stirring at room temperature for 30 min, n-propyl bromide (0.69 g, 5.61 mmol) was added, and the reaction was stopped after reflux for 12 h. After the reaction solution cooled to room temperature, the solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by silica gel column chromatography using a dichloromethane / petroleum ether (v / v, 2:1) mixture as the developing solvent, and then reprecipitated in a dichloromethane / n-hexane system to obtain a white powder (yield 77.7%).

[0085] The synthetic route for compound (Ⅳ) is shown below:

[0086]

[0087] The method for synthesizing compound (V) is as follows:

[0088] Under an argon atmosphere, compound (I) 5H-benzo[a]benzo[4,5]thieno[3,2-c]carbazole (0.20 g, 0.62 mmol) and sodium hydride (0.59 g, 2.48 mmol) of formula (I) were added sequentially to 20 mL of ultra-dry tetrahydrofuran. After stirring at room temperature for 30 min, bromobutane (0.65 g, 4.74 mmol) was added, and the reaction was stopped after reflux for 12 h. After the reaction solution cooled to room temperature, the solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by silica gel column chromatography using a dichloromethane / petroleum ether (v / v, 2:1) mixture as the developing solvent, and then reprecipitated in a dichloromethane / n-hexane system to obtain a white powder (yield 74.6%).

[0089] The synthetic route for compound (V) is shown below:

[0090]

[0091] Example 1

[0092] This embodiment prepares an organic long afterglow material, specifically a melamine-formaldehyde resin-based organic long afterglow material doped with compound (I). This embodiment includes the following four steps:

[0093] S1. Weigh 10 mg of compound (Ⅰ) and dissolve it in 1 mL of tetrahydrofuran to prepare solution A with a concentration of 10 mg / mL;

[0094] S2. Add 5.224g of melamine to 5.34mL of a 37% formaldehyde aqueous solution, then add triethanolamine to adjust the pH of the solution to 8-9, and heat at 90℃ for 10min to form a clear solution B;

[0095] S3. Add 1 mL of the above solution A to solution B, then add it to a 10 mg / mL PVA aqueous solution at 60 °C, quickly adjust the pH to 5-6 with acetic acid, and stir at 500 r / min for 30 min.

[0096] S4. Centrifuge the polymer emulsion obtained in step S3 at 5000 r / min for 5 min, then wash it with deionized water 3 to 4 times, and vacuum dry it at 50℃ for 24 h to obtain polymer microsphere organic long afterglow material with afterglow effect and a particle size of 2 μm.

[0097] Example 2

[0098] This embodiment prepares an organic long afterglow material, specifically a melamine-formaldehyde resin-based organic long afterglow material doped with compound (II). This embodiment includes the following four steps:

[0099] S1. Weigh 10 mg of compound (II) and dissolve it in 1 mL of tetrahydrofuran to prepare solution A with a concentration of 10 mg / mL;

[0100] S2. Add 5.224g of melamine to 5.34mL of 37% formaldehyde aqueous solution, then add triethanolamine to adjust the pH of the solution to 8-9, and heat at 90℃ for 10min to form a clear solution B.

[0101] S3. Add 1 mL of the above solution A to solution B, then add it to a 10 mg / mL PVA aqueous solution at 60 °C, quickly adjust the pH to 5-6 with acetic acid, and stir at 500 r / min for 30 min.

[0102] S4. Centrifuge the polymer emulsion obtained in step S3 at 5000 r / min for 5 min, then wash it with deionized water 3 to 4 times, and vacuum dry it at 50℃ for 24 h to obtain polymer microsphere organic long afterglow material with afterglow effect and a particle size of 2 μm.

[0103] Example 3

[0104] This embodiment prepares an organic long afterglow material, specifically a melamine-formaldehyde resin-based organic long afterglow material doped with compound (III). This embodiment includes the following four steps:

[0105] S1. Weigh 10 mg of compound (III) and dissolve it in 1 mL of tetrahydrofuran to prepare solution A with a concentration of 10 mg / mL;

[0106] S2. Add 5.224g of melamine to 5.34mL of a 37% formaldehyde aqueous solution, then add triethanolamine to adjust the pH of the solution to 8-9, and heat at 90℃ for 10min to form a clear solution B.

[0107] S3. Add 1 mL of the above solution A to solution B, then add it to a 10 mg / mL PVA aqueous solution at 60 °C, quickly adjust the pH to 5-6 with acetic acid, and stir at 500 r / min for 30 min.

[0108] S4. Centrifuge the polymer emulsion obtained in step S3 at 5000 r / min for 5 min, then wash it with deionized water 3 to 4 times, and vacuum dry it at 50℃ for 24 h to obtain polymer microsphere organic long afterglow material with afterglow effect and a particle size of 2 μm.

[0109] Example 4

[0110] This embodiment prepares an organic long afterglow material, specifically a melamine-formaldehyde resin-based organic long afterglow material doped with compound (Ⅳ). This embodiment includes the following four steps:

[0111] S1. Weigh 10 mg of compound (Ⅳ) and dissolve it in 1 mL of tetrahydrofuran to prepare solution A with a concentration of 10 mg / mL;

[0112] S2. Add 5.224g of melamine to 5.34mL of a 37% formaldehyde aqueous solution, then add triethanolamine to adjust the pH of the solution to 8-9, and heat at 90℃ for 10min to form a clear solution B.

[0113] S3. Add 1 mL of the above solution A to solution B, then add it to a 10 mg / mL PVA aqueous solution at 60 °C, quickly adjust the pH to 5-6 with acetic acid, and stir at 500 r / min for 30 min.

[0114] S4. Centrifuge the polymer emulsion obtained in step S3 at 5000 r / min for 5 min, then wash it with deionized water 3 to 4 times, and vacuum dry it at 50℃ for 24 h to obtain polymer microsphere organic long afterglow material with afterglow effect and a particle size of 2 μm.

[0115] Example 5

[0116] This embodiment prepares an organic long afterglow material, specifically a melamine-formaldehyde resin-based organic long afterglow material doped with compound (V). This embodiment includes the following four steps:

[0117] S1. Weigh 10 mg of compound (V) and dissolve it in 1 mL of tetrahydrofuran to prepare solution A with a concentration of 10 mg / mL;

[0118] S2. Add 5.224g of melamine to 5.34mL of a 37% formaldehyde aqueous solution, then add triethanolamine to adjust the pH of the solution to 8-9, and heat at 90℃ for 10min to form a clear solution B.

[0119] S3. Add 1 mL of the above solution A to solution B, then add it to a 10 mg / mL PVA aqueous solution at 60 °C, quickly adjust the pH to 5-6 with acetic acid, and stir at 500 r / min for 30 min.

[0120] S4. Centrifuge the polymer emulsion obtained in step S3 at 5000 r / min for 5 min, then wash it with deionized water 3 to 4 times, and vacuum dry it at 50℃ for 24 h to obtain polymer microsphere organic long afterglow material with afterglow effect and a particle size of 2 μm.

[0121] Example 6

[0122] This embodiment prepares an organic long afterglow material, specifically a melamine-formaldehyde resin-based organic long afterglow material doped with compound (I). This embodiment includes the following four steps:

[0123] S1. Weigh 10 mg of compound (Ⅰ) and dissolve it in 1 mL of tetrahydrofuran to prepare solution A with a concentration of 10 mg / mL;

[0124] S2. Add 5.224g of melamine to 5.34mL of a 37% formaldehyde aqueous solution, then add triethanolamine to adjust the pH of the solution to 8-9, and heat at 90℃ for 10min to form a clear solution B.

[0125] S3. Add 1 mL of the above solution A to solution B, then add it to a 10 mg / mL PVP aqueous solution at 60 °C, quickly adjust the pH to 5-6 with acetic acid, and stir at 500 r / min for 30 min.

[0126] S4. Centrifuge the polymer emulsion obtained in step S3 at 5000 r / min for 5 min, then wash it with deionized water 3 to 4 times, and vacuum dry it at 50℃ for 24 h to obtain polymer microsphere organic long afterglow material with afterglow effect and a particle size of 2 μm.

[0127] Example 7

[0128] This embodiment prepares an organic long afterglow material, specifically a melamine-formaldehyde resin-based organic long afterglow material doped with compound (I). This embodiment includes the following four steps:

[0129] S1. Weigh 10 mg of compound (Ⅰ) and dissolve it in 1 mL of tetrahydrofuran to prepare solution A with a concentration of 10 mg / mL;

[0130] S2. Add 5.224g of melamine to 5.34mL of a 37% formaldehyde aqueous solution, then add triethanolamine to adjust the pH of the solution to 8-9, and heat at 90℃ for 10min to form a clear solution B.

[0131] S3. Add 1 mL of the above solution A to solution B, then add it to a 7.5 mg / mL PVP aqueous solution at 60℃, quickly adjust the pH to 5-6 with acetic acid, and stir at 500 r / min for 30 min.

[0132] S4. Centrifuge the polymer emulsion obtained in step S3 at 5000 r / min for 5 min, then wash it with deionized water 3 to 4 times, and vacuum dry it at 50℃ for 24 h to obtain polymer microsphere organic long afterglow material with afterglow effect and a particle size of 2.5 μm.

[0133] Example 8

[0134] This embodiment prepares an organic long afterglow material, specifically a melamine-formaldehyde resin-based organic long afterglow material doped with compound (I). This embodiment includes the following four steps:

[0135] S1. Weigh 10 mg of compound (Ⅰ) and dissolve it in 1 mL of tetrahydrofuran to prepare solution A with a concentration of 10 mg / mL;

[0136] S2. Add 5.224g of melamine to 5.34mL of a 37% formaldehyde aqueous solution, then add triethanolamine to adjust the pH of the solution to 8-9, and heat at 90℃ for 10min to form a clear solution B.

[0137] S3. Add 1 mL of the above solution A to solution B, then add it to a 3 mg / mL PVP aqueous solution at 60℃, quickly adjust the pH to 5-6 with acetic acid, and stir at 500 r / min for 30 min.

[0138] S4. Centrifuge the polymer emulsion obtained in step S3 at 5000 r / min for 5 min, then wash it with deionized water 3 to 4 times, and vacuum dry it at 50℃ for 24 h to obtain polymer microsphere organic long afterglow material with afterglow effect and a particle size of 4 μm.

[0139] Example 9

[0140] This embodiment prepares an organic long afterglow material, specifically a melamine-formaldehyde resin-based organic long afterglow material doped with compound (I). This embodiment includes the following four steps:

[0141] S1. Weigh 10 mg of compound (Ⅰ) and dissolve it in 1 mL of tetrahydrofuran to prepare solution A with a concentration of 10 mg / mL;

[0142] S2. Add 5.224g of melamine to 5.34mL of a 37% formaldehyde aqueous solution, then add triethanolamine to adjust the pH of the solution to 8-9, and heat at 90℃ for 10min to form a clear solution B.

[0143] S3. Add 1 mL of the above solution A to solution B, then add it to deionized water at 60℃, quickly adjust the pH to 5-6 with acetic acid, and stir at 500 r / min for 30 min.

[0144] S4. Centrifuge the polymer emulsion obtained in step S3 at 5000 r / min for 5 min, then wash it with deionized water 3 to 4 times, and vacuum dry it at 50℃ for 24 h to obtain polymer microsphere organic long afterglow material with afterglow effect and a particle size of 5 μm.

[0145] Example 10

[0146] This embodiment prepares an anti-counterfeiting material, including the polymer microsphere organic long afterglow material prepared in Example 1. The preparation method includes the following steps:

[0147] S1. Add 6.5g EVA to 40mL of ethyl acetate, heat and stir to dissolve;

[0148] S2. Prepare a 50 mg / mL ethyl acetate solution of the polymer microsphere organic long afterglow material obtained in Example 1 and add it to the solution obtained in S1.

[0149] S3. Pour the solution obtained in step S2 into a silicone mold and heat to dry the solvent to obtain a three-dimensional anti-counterfeiting material with afterglow effect.

[0150] Performance testing

[0151] The pure solid powders (microcrystals) of compounds of formulas (Ⅰ) to (Ⅴ) were subjected to 1H NMR spectroscopy. Figures 1-5 The images show the proton NMR spectra of compounds (I) to (V) in Examples 1 to 5 of this invention. The tests confirmed that compounds (I) to (V) have the target structure.

[0152] The optical properties and microsphere particle size of the polymer microsphere organic long afterglow materials in Examples 1-5 were tested to investigate the particle size, afterglow emission spectrum, and afterglow lifetime of the materials. All tests were performed on an Edinburgh FLS980 steady-state and transient fluorescence spectrometer with an integrating sphere and a ZEISS Gemini 500 field emission scanning electron microscope.

[0153] Figure 6 These are the steady-state emission spectra of the solid powders of compounds of formulas (Ⅰ) to (Ⅴ) in Examples 1 to 5 of this invention. Figure 6 It can be seen that the solid powders of compounds (I) to (V) do not produce long afterglow luminescence after being excited by ultraviolet light. They only have high luminescence intensity in the wavelength range of 400 to 500 nm, that is, they only emit transient fluorescence. The solid powders of compounds (I) to (V) themselves do not have afterglow properties.

[0154] Figure 7 This is a graph showing the luminescence decay curves of the solid powder compounds in Examples 1-5 of this invention. Figure 7It can be seen that the duration of luminescence of the solid powders of compounds (I) to (V) after ultraviolet light excitation is very short, with fitted lifetime values ​​of 1.25 ns, 2.03 ns, 1.70 ns, 1.56 ns and 1.37 ns, respectively. That is, the solid powders of compounds (I) to (V) do not have afterglow properties, and the luminescence intensity decays rapidly.

[0155] Figures 8-12 The images shown are scanning electron microscope (SEM) images of the organic long afterglow materials in Examples 1, 6-9 of this invention. Figures 8-12 It can be seen that in Examples 1 and 6-9, microspherical organic long afterglow materials were prepared by emulsion polymerization using compound (I) as the guest molecule and melamine-formaldehyde resin as the main body. In Examples 1 and 6, by changing the type of emulsifier while ensuring the same amount of addition, polymer microspheres with a particle size of 2 μm were obtained. In Examples 6-8, the same type of emulsifier was used, but the amount was different, and the particle sizes of the polymer microspheres prepared were 2 μm, 2.5 μm, and 4 μm, respectively. This shows that the particle size of microspheres can be controlled by changing the type and amount of emulsifier during the preparation of polymer microsphere materials. In Example 9, without adding an emulsifier during emulsion polymerization, the surface of the obtained polymer microspheres was rough and the particle size was 5 μm. This shows that adding an emulsifier during emulsion polymerization can adjust the size of the emulsion droplets in the emulsion and affect the viscosity and consistency of the latex. Existing technologies produce organic long-afterglow materials that are essentially monolithic polymers rather than microscale materials. The polymer microsphere organic long-afterglow material provided by this invention is a uniformly sized microsphere, and the particle size can be controlled by changing the type and amount of emulsifier.

[0156] Figures 13-17 These are the steady-state emission spectra and afterglow emission spectra of the organic long afterglow materials in Examples 1-5 of this invention, respectively. Figures 13-17 It can be seen that the steady-state emission of the organic long afterglow materials in Examples 1 to 5 is all around 400 nm, and the maximum emission peak of the delayed spectrum is all around 550 nm.

[0157] Figure 18 This is a graph showing the afterglow decay curves of the organic long afterglow materials in Examples 1-5 of the present invention. Figure 18 It can be seen that the lifetimes of the maximum emission peaks in the delayed spectra of the organic long-afterglow materials in Examples 1 to 5 can all reach the millisecond level and are greater than 100 ms. Their fitted lifetime values ​​are 0.509 s, 0.538 s, 0.610 s, 0.632 s and 0.775 s, respectively. This indicates that the present invention can prepare microspherical organic long-afterglow materials with controllable particle size while ensuring that the long-afterglow performance of the materials is not affected.

[0158] Figure 19 These are images illustrating the afterglow luminescence phenomenon of the organic long afterglow materials in Examples 1-5 of this invention. Figure 19 It can be seen that the organic long afterglow materials in Examples 1 to 5 can produce a bright yellow afterglow after being activated by ultraviolet light, and the brightness is uniform. This indicates that the organic long afterglow materials provided by the present invention have uniform dispersion of guest molecules in the polymer, and the materials have good application potential in fields such as anti-counterfeiting, data encryption, functional inks, and road markings.

[0159] Figure 20 This is a demonstration diagram illustrating the application of the anti-counterfeiting material in Embodiment 6 of the present invention. Figure 20 It is known that the anti-counterfeiting material, including the organic long afterglow material in Example 1, can produce a bright green afterglow after being activated by an ultraviolet lamp, and has good anti-counterfeiting and authenticity identification capabilities.

[0160] This invention utilizes aromatic organic compounds containing heteroatoms N and S as guest molecules and melamine-formaldehyde resin as the main component. Through emulsion polymerization, a polymer microsphere luminescent material is prepared that emits a long-lasting and stable afterglow at room temperature. The lifetime of the maximum emission peak in the delayed spectrum can reach over 100 ms, meeting the performance requirements for long-lasting materials in fields such as anti-counterfeiting, data encryption, functional inks, and road marking. The particle size of the melamine-formaldehyde resin microsphere afterglow material can be controlled by varying the surfactant content used in the emulsion polymerization process. Anti-counterfeiting materials synthesized using organic long-lasting materials produce a bright green afterglow after activation by ultraviolet light, meeting the requirements for product anti-counterfeiting and authenticity verification, and demonstrating strong practicality.

Claims

1. An organic long afterglow material, characterized in that, It includes the main component and guest molecules doped in the main component; The main component is melamine-formaldehyde resin; The guest molecule is an aromatic organic compound containing heteroatoms N and S; The aromatic organic compound containing heteroatoms N and S is selected from at least one of formulas (II) to (V): 。 2. The organic long afterglow material according to claim 1, characterized in that, In the organic long afterglow material, the mass fraction of guest molecules is 0.05~0.5%.

3. The organic long afterglow material according to claim 1, characterized in that, The organic long afterglow material is spherical in shape and has a particle size of 2~8μm.

4. The method for preparing the organic long afterglow material according to any one of claims 1 to 3, characterized in that, Includes the following steps: 1) An aromatic organic compound containing heteroatoms N and S is mixed with an organic solvent to obtain solution A; 2) Mix melamine and formaldehyde aqueous solution, add alkali to adjust the pH to 7-11, heat to react, and obtain solution B; 3) Mix solution A with solution B, then mix with emulsifier, add acid to adjust the pH to 4-6, and react to obtain polymer emulsion; 4) The polymer emulsion is centrifuged, washed, and dried to obtain the organic long afterglow material.

5. The preparation method according to claim 4, characterized in that, In step 1), the solid-liquid ratio of the aromatic organic compound containing heteroatoms N and S to the organic solvent is (8~15) mg: 1 mL; And / or, the organic solvent is selected from one of methanol, ethanol, acetone, dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran, and acetonitrile.

6. The preparation method according to claim 4, characterized in that, In step 2), the molar ratio of melamine to formaldehyde is 1: (1~5); And / or, the base is selected from one of amines, alkali metal hydroxides, and alkali metal carbonates; And / or, the temperature of the heating reaction is 80~110℃; the time is 5~20min.

7. The preparation method according to claim 4, characterized in that, In step 3), the volume ratio of solution A, solution B and emulsifier is 1: (5~10): (50~150); And / or, the concentration of the emulsifier is 2~15 mg / mL; And / or, the emulsifier is selected from at least one of polyvinylpyrrolidone and polyvinyl alcohol; And / or, the acid is selected from acetic acid, oxalic acid, hydrochloric acid, and sulfuric acid; And / or, the reaction temperature is 40~70℃; the time is 15~40min.

8. An anti-counterfeiting material, characterized in that, Includes the organic long afterglow material as described in any one of claims 1 to 3; The anti-counterfeiting material also includes a polymer; the mass ratio of the organic long afterglow material to the polymer is 1:(15~20).

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