Phosphate matrix composite fluorescent powder and preparation method thereof

Abstract

The invention discloses phosphate matrix composite fluorescent powder and a preparation method thereof, belongs to the technical field of solid luminescent materials, and aims to solve the problems that a single phosphate fluorescent material in the prior art is low in luminous efficiency and short in excitation spectrum; the thermal stability of the added organic light-emitting material is poor, and the like. The invention relates to a preparation method of phosphate matrix composite fluorescent powder. The preparation method comprises the following steps: coating a composite inorganic fluorescent material containing divalent europium and ammonium phosphite with modified polylactic acid; benzidine and (3-bromophenyl)-9H-carbazole react and then are matched with iridium trichloride hydrate, and the high-molecular organic fluorescent material is obtained. And self-assembling the high-molecular organic fluorescent material and calixarene to obtain the composite high-molecular fluorescent material. The phosphate matrix composite fluorescent powder prepared by the invention has the advantages of long spectral range and high thermal stability.

Description

Technical Field

[0001] The invention relates to the technical field of solid luminescent materials, and in particular to a phosphate matrix composite phosphor and a preparation method thereof. Background Art

[0002] With the increasing demand for phosphors in the fields of LED, display screens, smart lighting, etc., the market's requirements for high-quality phosphors are also gradually increasing. At present, the most mainstream commercial phosphors in the market include yttrium aluminum garnet phosphors, phosphate phosphors, nitride phosphors, etc. Among them, phosphate phosphors have the advantages of low production cost, safety and environmental protection. However, the existing phosphate phosphors have low luminous efficiency and short emission spectrum, which limits their luminous range in the visible spectrum.

[0003] When synthesizing phosphate phosphors, doping with activators or sensitizers can enhance the fluorescence efficiency and increase the spectral range; if an appropriate amount of activators can be doped into phosphate phosphors, it will help improve the luminescence efficiency of phosphate phosphors. However, the selection of which activators to dope into phosphate phosphors to effectively improve the luminescence intensity and expand the luminescence spectrum of phosphate fluorescent materials is a technical problem that needs to be solved urgently.

[0004] There are many types of organic luminescent materials and their derivatives, which are easy to synthesize and highly sensitive. If an appropriate amount of organic luminescent materials can be added to phosphate phosphors, the luminous efficiency of phosphate phosphors can be improved and the luminescent spectrum can be expanded. However, the thermal stability of organic luminescent materials themselves is poor, and their luminescent effect is easily affected by the external environment. If organic luminescent materials are added to phosphate-based phosphors, how to improve their own thermal stability is also a technical problem that needs to be solved.

[0005] In view of the technical defects in this aspect, a solution is now proposed. Summary of the invention

[0006] The purpose of the present invention is to provide a phosphate matrix composite phosphor and a preparation method thereof, so as to solve the technical problem that a single phosphate fluorescent material in the prior art has low luminous efficiency and a short emission spectrum; in addition, in order to expand the spectral width of the phosphate fluorescent material, the added organic luminescent material has poor thermal stability.

[0007] The purpose of the present invention can be achieved through the following technical solutions: A method for preparing a phosphate matrix composite phosphor comprises the following steps: S1. Mixing the modified phosphate fluorescent material and the composite polymer fluorescent material in a mass ratio of 2-3:1, grinding and crushing to obtain a composite mixed powder; S2. The composite mixed powder is added into a spiral screening machine for screening to obtain a phosphate matrix composite phosphor.

[0008] Furthermore, in step S1, the method for preparing the modified phosphate fluorescent material comprises the following steps: A1. Dissolve europium oxide in a dilute nitric acid solution, then heat to 115-120° C. and evaporate to dryness to obtain europium nitrate crystals; Mix potassium carbonate, magnesium oxide, ammonium phosphite and europium nitrate crystals as raw materials, grind them, and obtain a ground raw material; A2. The ground raw materials are reacted at 100-200°C for 1-2h, and then heated at 800-900°C for 2-3h to obtain a mixed powder; the mixed powder is naturally cooled to room temperature, and then ground again to obtain fine powder; hydrogen and nitrogen are mixed in a volume ratio of 1:9 to form a mixed gas atmosphere; the fine powder is placed in the mixed gas atmosphere, and is subjected to a constant temperature reaction at 1100-1200°C for 6-8h, and then naturally cooled to room temperature and discharged, and the obtained powder crystals are the composite inorganic phosphor material K （1-X） MgPO3:XEu 2+ ; The present invention adopts a high-temperature solid phase method to synthesize a composite inorganic fluorescent material.

[0009] A3, mixing polylactic acid-glycolic acid copolymer and acetone, then adding acrylamide, stirring and dissolving to obtain a reactant; the reactant is refluxed at 80-90° C. for 2-3 hours to obtain a product; the product is post-processed to obtain a modified polylactic acid; The carboxyl group of the polylactic acid-glycolic acid copolymer can react with the amino group of acrylamide to obtain modified polylactic acid.

[0010] A4. Add the modified polylactic acid and the composite inorganic fluorescent powder into a twin-screw extruder, and melt-extrude at 185-200° C. to obtain a modified phosphate fluorescent material.

[0011] Furthermore, in step A1, the concentration of the dilute nitric acid solution is 2-3 mol / L, the dosage ratio of europium oxide and dilute nitric acid solution is 3-5 g:100 mL, and the weight ratio of potassium carbonate, magnesium oxide, ammonium phosphite and europium nitrate crystals is 14-28:2-4:40-80:23-46; in step A2, the mixture is placed in a mortar for secondary grinding, and the duration of the secondary grinding is 10-20 min.

[0012] Furthermore, in step A3, the weight ratio of polylactic acid-glycolic acid copolymer, acetone and acrylamide is 20-25:100:5-10; the post-process treatment of the product includes: the product is further evaporated at 80-90°C to remove the organic solvent acetone to obtain a solid; the solid is washed with deionized water, dried to constant weight, and crushed to 200-300 mesh to obtain modified polylactic acid; in step A4, the mass ratio of modified polylactic acid and composite inorganic fluorescent powder is 1:1-2.

[0013] Furthermore, in step S1, the method for preparing the composite polymer fluorescent material comprises the following steps: B1. Add benzidine, (3-bromophenyl)-9H-carbazole, cesium acetate and cesium carbonate into toluene, mix and stir evenly to obtain a reaction system; B2, placing the reaction system under a nitrogen atmosphere, heating it to 115-120° C., and reflux reacting at this temperature for 24-48 hours. After the reaction is completed, cooling it to room temperature to obtain a product; the product is post-processed to obtain a solid modified carbazole; Using cesium acetate as a catalyst and cesium carbonate as a catalyst promoter to provide an alkaline environment, the amino group contained in benzidine reacts with the bromide ion in 9-(3-bromophenyl)-9H-carbazole to undergo a nucleophilic substitution reaction to prepare the product. The product is extracted with a CH2Cl2-H2O system to remove the catalyst cesium acetate and the catalyst promoter cesium carbonate; the organic solvent toluene is removed by organic phase subtraction distillation to obtain the product, which is the modified carbazole.

[0014] The reaction formula of benzidine and 9-(3-bromophenyl)-9H-carbazole to obtain modified carbazole is as follows: ; B3, the modified carbazole, hydrated iridium trichloride and organic solvent are mixed to obtain a reactant; the reactant is placed in a nitrogen atmosphere, refluxed at 130-150° C. for 20-24 hours, and cooled to room temperature after the reaction to obtain a mixture; the mixture is post-processed to obtain a polymer organic fluorescent material; The imino group contained in the modified carbazole undergoes coordination reaction with hydrated iridium trichloride to form a complex, which is the polymer fluorescent material prepared by the present invention.

[0015] ; B4. The calixarene mother liquor and the polymer organic fluorescent material are mixed to obtain a mixed material; ultrapure water is added to the mixed material to make the volume to 100 mL, and the mixture is allowed to stand at room temperature for 2-3 hours, and the gel material is collected to obtain a composite polymer fluorescent material.

[0016] Calixarene has a hydrophobic cavity size, a hydrophilic carboxyl group at the upper end, and a hydrophobic alkyl chain at the lower end. The polymer organic fluorescent material and the calixarene undergo a self-assembly reaction through electrostatic adsorption to obtain a composite polymer fluorescent material.

[0017] Furthermore, in step B1, the amount ratio of toluene, benzidine, (3-bromophenyl)-9H-carbazole, cesium acetate and cesium carbonate is 200mL:18-20g:10-15g:3-5g:5-10g; in step B2, the post-processing steps of the product include: the product is extracted three times with a CH2Cl2-H2O system, and the organic phase is collected; the organic phase is distilled at 112-115°C to remove the solvent toluene to obtain a solid; the solid is washed with deionized water to neutrality, and then vacuum dried at 80-90°C to constant weight to obtain a solid modified carbazole.

[0018] Furthermore, in step B3, the organic solvent is obtained by mixing ethanol and water in a volume ratio of 3:1; the amount ratio of the modified carbazole, hydrated iridium trichloride and the organic solvent is 30-40g:2-5g:125-150mL; the post-processing steps of the mixture include: the mixture is allowed to stand at room temperature until the solid no longer precipitates, and then filtered to obtain a product; the product is rinsed three times with an organic solvent, and then vacuum dried at 60-70°C to constant weight to obtain a polymer organic fluorescent material.

[0019] Furthermore, in step B4, the calixarene mother liquor is prepared by the following steps: mixing calixarene and acetone to obtain a mother liquor; adding sodium phosphate buffer solution dropwise to the mother liquor, adjusting the pH value of the mother liquor to 6-7, and obtaining a calixarene mother liquor; the amount ratio of calixarene, acetone and polymer organic fluorescent material is 10-15g:60-80mL:5-6g; and the calixarene mother liquor and the polymer organic fluorescent material are diluted to 100mL with ultrapure water.

[0020] As another aspect of the present invention, a method for preparing a phosphate-based composite phosphor provides a phosphate-based composite phosphor.

[0021] The present invention has the following beneficial effects: 1. Phosphate phosphor crystals are made of PO4 -The tetrahedrons share vertices to form a three-dimensional framework structure, constructing a space environment with high rigidity and strength. When synthesizing modified phosphate fluorescent materials, doping with europium ion activators can increase the luminescence intensity of phosphate fluorescent materials. Compared with trivalent europium ions, divalent europium ions have a wider emission spectrum; in addition, divalent europium ions can be used as sensitizers to absorb light energy and transfer it to other luminescence centers, thereby obtaining multiple excitation spectra. Europium ions usually exist in nature in a +3 valence state, and divalent europium ions generally need to be obtained through a reducing agent; however, doping with additives will affect the crystal structure of the synthesized phosphate phosphor, thereby affecting the luminescence characteristics of the synthesized phosphor. In the present invention, ammonium phosphite is used as a reducing agent, and trivalent europium ions are first reduced to divalent europium ions at a relatively low temperature (100-200°C), and then a high-temperature solid-phase method is used to synthesize the modified phosphate fluorescent material. The modified phosphate fluorescent material prepared by the present invention has the characteristics of wide spectral coverage, high conversion efficiency and excellent thermal stability.

[0022] 2. Modify the composite inorganic fluorescent material with polylactic acid-glycolic acid copolymer, thereby improving the mechanical properties and heat resistance of the modified phosphate fluorescent material; in addition, the compatibility of the composite inorganic fluorescent material with the polymer organic fluorescent material can be improved. The polylactic acid-glycolic acid copolymer is pre-grafted with acrylamide, which can further increase the molecular weight of the polylactic acid-glycolic acid copolymer and improve the thermal stability of the polylactic acid-glycolic acid copolymer. On the other hand, the above-mentioned modified polylactic acid has the performance of adsorbing resin to a certain extent, which can further improve its own adsorption performance for phosphate fluorescent materials, thereby preparing a modified phosphate fluorescent material.

[0023] 3. In addition to synthesizing inorganic phosphors, the present invention also adds a certain amount of polymer organic fluorescent materials to expand its wavelength adsorption range. (3-bromophenyl)-9H-carbazole contains a benzene ring and a carbazole ring structure, and then reacts with benzidine to obtain a modified carbazole with a multi-phenyl ring structure. The modified carbazole is then coordinated with hydrated iridium trichloride to obtain a polymer fluorescent material. The larger the conjugated π bond of the polymer fluorescent material, the larger the delocalization range of the electrons, which is easy to be excited into high-energy excited state molecules. The polymer fluorescent material synthesized by the present invention has high phosphorescence efficiency. In order to suppress the radiationless motion of the luminescent molecules and stabilize the triplet excitons, the polymer fluorescent material is used as a guest and introduced into the host macrocyclic molecular calixarene to form a stable inclusion complex. According to performance testing, the phosphate-based composite phosphor obtained by mixing modified phosphate fluorescent materials and composite polymer fluorescent materials has multiple luminescent centers, is mixed and ground according to a certain mass ratio, and then added to a spiral screening machine for screening. The spiral screening machine contains a multi-layer spiral structure design to ensure the uniformity of the mixed material in all dimensions, thereby further improving the purity and consistency of the prepared phosphate-based composite phosphor. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The polylactic acid-glycolic acid copolymer used in Examples 1-3 of the present invention was purchased from Yuanye Biotechnology with a product number of S22436-1 and a molecular weight of 10,000-20,000.

[0026] Example 1 This embodiment provides a method for preparing a modified phosphate fluorescent material for a phosphate matrix composite phosphor, comprising the following steps: A1. Add 100 mL of 2 mol / L dilute nitric acid solution and 3 g of europium oxide to a 250 mL short-necked round-bottomed flask, stir and dissolve to obtain a mixed solution; then seal with a ground stopper, transfer the short-necked round-bottomed flask to a constant temperature water bath, heat to 115°C, evaporate to dryness, and collect europium nitrate crystals. According to weight parts, 14 parts of potassium carbonate, 4 parts of magnesium oxide, 40 parts of ammonium phosphite and 45 parts of europium nitrate crystals are added as raw materials to an agate mortar and ground for 20 minutes to obtain a ground raw material.

[0027] A2. Put the ground raw materials into a box-type resistance furnace, set it to react at 100℃ for 1h, and then heat it at 800℃ for 2h to obtain a mixed powder; cool the mixed powder naturally to room temperature, and then continue to grind it in an agate mortar for 10min to obtain fine powder. Hydrogen and nitrogen are introduced into the tubular furnace at the same time, and the volume ratio of hydrogen and nitrogen in the tubular furnace is 1:9, so that the tubular furnace is placed in a mixed gas atmosphere. Then transfer the fine powder to the tubular furnace, react at a constant temperature of 1100℃ for 6h, and then naturally cool to room temperature and discharge the material. The obtained powder crystal is the composite inorganic fluorescent material.

[0028] A3. According to the weight, add 20 parts of polylactic acid-glycolic acid copolymer and 100 parts of acetone into a 500mL three-necked round-bottom flask, mix well, and then add 5 parts of acrylamide, stir and dissolve to obtain a reactant. The reactant is transferred to a thermostat and refluxed at 90°C for 2h to obtain a product. The product is further evaporated at 80°C to remove the organic solvent acetone to obtain a solid; the solid is washed with deionized water, dried at 60°C to constant weight, and crushed to 200 mesh, which is a modified polylactic acid.

[0029] A4. The modified polylactic acid and the composite inorganic fluorescent powder are added into a twin-screw extruder in a mass ratio of 1:1, and melt-extruded at 185° C. to obtain a modified phosphate fluorescent material.

[0030] Example 2 This embodiment provides a method for preparing a modified phosphate fluorescent material for a phosphate matrix composite phosphor, comprising the following steps: A1. Add 100 mL of 2.5 mol / L dilute nitric acid solution and 4 g of europium oxide to a 250 mL short-necked round-bottomed flask, stir and dissolve to obtain a mixed solution; then seal with a ground stopper, transfer the short-necked round-bottomed flask to a constant temperature water bath, heat to 118°C, evaporate to dryness, and collect europium nitrate crystals. According to weight parts, 21 parts of potassium carbonate, 6 parts of magnesium oxide, 60 parts of ammonium phosphite and 68 parts of europium nitrate crystals are added as raw materials to an agate mortar and ground for 25 minutes to obtain the ground raw material.

[0031] A2. Put the ground raw materials into a box-type resistance furnace, set it to react at 130℃ for 1.6h, and then heat it at 850℃ for 2.5h to obtain a mixed powder; cool the mixed powder naturally to room temperature, and then continue to grind it in an agate mortar for 16min to obtain fine powder. Hydrogen and nitrogen are introduced into the tubular furnace at the same time, and the volume ratio of hydrogen and nitrogen in the tubular furnace is 1:9, so that the tubular furnace is placed in a mixed gas atmosphere. Then transfer the fine powder to the tubular furnace, react at a constant temperature of 1500℃ for 7h, and then naturally cool to room temperature and discharge the material. The obtained powder crystal is the composite inorganic fluorescent material.

[0032] A3. According to the weight, add 22 parts of polylactic acid-glycolic acid copolymer and 100 parts of acetone into a 500mL three-necked round-bottom flask, mix well, and then add 8 parts of acrylamide, stir and dissolve to obtain a reactant. The reactant is transferred to a thermostat and refluxed at 85°C for 2.5 hours to obtain a product. The product is further evaporated at 86°C to remove the organic solvent acetone to obtain a solid; the solid is washed with deionized water, dried at 66°C to constant weight, and crushed to 220 mesh, which is a modified polylactic acid.

[0033] A4. The modified polylactic acid and the composite inorganic fluorescent powder are added into a twin-screw extruder in a mass ratio of 1:2, and melt-extruded at 195° C. to obtain a modified phosphate fluorescent material.

[0034] Example 3 This embodiment provides a method for preparing a modified phosphate fluorescent material for a phosphate matrix composite phosphor, comprising the following steps: A1. Add 100 mL of 3 mol / L dilute nitric acid solution and 5 g of europium oxide to a 250 mL short-necked round-bottomed flask, stir and dissolve to obtain a mixed solution; then seal with a ground stopper, transfer the short-necked round-bottomed flask to a constant temperature water bath, heat to 120°C, evaporate to dryness, and collect europium nitrate crystals. According to weight parts, 28 parts of potassium carbonate, 8 parts of magnesium oxide, 80 parts of ammonium phosphite and 90 parts of europium nitrate are added as raw materials to an agate mortar and ground for 30 minutes to obtain the ground raw material.

[0035] A2. Put the ground raw materials into a box-type resistance furnace, set it to react at 200℃ for 2h, and then heat it at 900℃ for 3h to obtain a mixed powder; cool the mixed powder naturally to room temperature, and then continue to grind it in an agate mortar for 20min to obtain fine powder. Hydrogen and nitrogen are introduced into the tubular furnace at the same time, and the volume ratio of hydrogen and nitrogen in the tubular furnace is 1:9, so that the tubular furnace is placed in a mixed gas atmosphere. Then transfer the fine powder to the tubular furnace, react at a constant temperature of 1200℃ for 8h, and then naturally cool to room temperature and discharge the material. The obtained powder crystal is the composite inorganic fluorescent material.

[0036] A3. According to the weight, add 25 parts of polylactic acid-glycolic acid copolymer and 100 parts of acetone into a 500mL three-necked round-bottom flask, mix well, and then add 10 parts of acrylamide, stir and dissolve to obtain a reactant. The reactant is transferred to a thermostat and refluxed at 80°C for 3h to obtain a product. The product is further evaporated at 90°C to remove the organic solvent acetone to obtain a solid; the solid is washed with deionized water, dried at 70°C to constant weight, and crushed to 300 mesh, which is a modified polylactic acid.

[0037] A4. The modified polylactic acid and the composite inorganic fluorescent powder are added into a twin-screw extruder in a mass ratio of 1:2, and melt-extruded at 200° C. to obtain a modified phosphate fluorescent material.

[0038] Example 4 This embodiment provides a method for preparing a phosphate-based composite phosphor, comprising the following steps: B1. Select a 500mL three-necked round-bottom flask, which is connected to a thermometer, a catheter and a magnetic stirrer. Add 200mL of solvent toluene to the three-necked round-bottom flask, and then add 18g of benzidine, 10g of 9-(3-bromophenyl)-9H-carbazole, 3g of cesium acetate and 5g of cesium carbonate in sequence, mix and stir evenly to obtain a reaction system.

[0039] B2. Fill the three-necked round-bottom flask with nitrogen to place the flask in a nitrogen atmosphere. Then transfer the three-necked round-bottom flask to an electric constant temperature water bath, heat it to 115°C, and reflux it for 24 hours at this temperature. After the reaction is completed, cool it to room temperature to obtain the product. The product is extracted three times with a CH2Cl2-H2O system (the mass ratio of CH2Cl2 and H2O is 7:3), and the organic phase is collected; the organic phase is distilled at 112°C to remove the solvent toluene to obtain a solid. The solid is washed with deionized water until neutral, and then vacuum dried at 80°C to constant weight to obtain a solid modified carbazole.

[0040] B3. Ethanol and water are mixed in a volume ratio of 3:1 to obtain an organic solvent. 30 g of modified carbazole, 2 g of hydrated iridium trichloride and 125 mL of organic solvent are added to a 500 mL three-necked round-bottom flask, and mixed evenly to obtain a reactant. The reactant is placed in a nitrogen atmosphere, accompanied by a stirring speed of 100 r / min, refluxed at 130 ° C for 24 h, and cooled to room temperature after the reaction to obtain a mixture. The mixture is allowed to stand at room temperature until no solid is precipitated, and then filtered to obtain a product; the product is rinsed three times with an organic solvent, and then vacuum dried at 60 ° C to constant weight to obtain a polymer organic fluorescent material.

[0041] B4. Add 10g of calixarene to 60mL of acetone, stir and dissolve to obtain a mother liquor. Add sodium phosphate buffer solution dropwise to the mother liquor, adjust the pH value of the mother liquor to 6, and obtain a calixarene mother liquor. Then add 5g of polymer fluorescent material to the calixarene mother liquor to obtain a mixed material. Add ultrapure water to the mixed material to make the volume to 100mL, let it stand at room temperature for 2h, collect the gel material, and obtain a composite polymer fluorescent material.

[0042] B5. The modified phosphate fluorescent material and the composite polymer fluorescent material prepared in Example 1 were mixed in a mass ratio of 2:1, and ground to 200 meshes to obtain a composite mixed powder. The composite mixed powder was added to a spiral sieving machine for sieving to obtain a phosphate matrix composite fluorescent powder.

[0043] Example 5 This embodiment provides a method for preparing a phosphate-based composite phosphor, comprising the following steps: B1. Select a 500mL three-necked round-bottom flask, which is connected to a thermometer, a catheter and a magnetic stirrer. Add 200mL of solvent toluene to the three-necked round-bottom flask, and then add 19g of benzidine, 12g of 9-(3-bromophenyl)-9H-carbazole, 4g of cesium acetate and 8g of cesium carbonate in sequence, mix and stir evenly to obtain a reaction system.

[0044] B2. Fill the three-necked round-bottom flask with nitrogen to place the flask in a nitrogen atmosphere. Then transfer the three-necked round-bottom flask to an electric constant temperature water bath, heat it to 118°C, and reflux it for 30 hours at this temperature. After the reaction is completed, cool it to room temperature to obtain the product. The product is extracted three times with a CH2Cl2-H2O system (the mass ratio of CH2Cl2 and H2O is 7:3), and the organic phase is collected; the organic phase is distilled at 113°C to remove the solvent toluene to obtain a solid. The solid is washed with deionized water until neutral, and then vacuum dried at 88°C to constant weight to obtain a solid modified carbazole.

[0045] B3, ethanol and water are mixed in a volume ratio of 3:1 to obtain an organic solvent. 35g of modified carbazole, 3g of hydrated iridium trichloride and 130mL of organic solvent are added to a 500mL three-necked round-bottom flask, and mixed evenly to obtain a reactant. The reactant is placed in a nitrogen atmosphere, accompanied by a stirring speed of 120r / min, and refluxed at 135°C for 22h. After the reaction is completed, it is cooled to room temperature to obtain a mixture. The mixture is allowed to stand at room temperature until no solid is precipitated, and then filtered to obtain a product; the product is rinsed three times with an organic solvent, and then vacuum dried at 65°C to constant weight to obtain a polymer organic fluorescent material.

[0046] B4. Add 12g of calixarene to 70mL of acetone, stir and dissolve to obtain a mother liquor. Add sodium phosphate buffer solution to the mother liquor, adjust the pH value of the mother liquor to 6.6, and obtain a calixarene mother liquor. Then add 5.5g of polymer fluorescent material to the calixarene mother liquor to obtain a mixed material; add ultrapure water to the mixed material to make the volume to 100mL, let it stand at room temperature for 2.5h, collect the gel material, and obtain a composite polymer fluorescent material.

[0047] B5. The modified phosphate fluorescent material and the composite polymer fluorescent material prepared in Example 2 were mixed in a mass ratio of 3:1, ground and crushed to 300 meshes to obtain a composite mixed powder. The composite mixed powder was added to a spiral sieving machine for sieving to obtain a phosphate matrix composite fluorescent powder.

[0048] Example 6 This embodiment provides a method for preparing a phosphate-based composite phosphor, comprising the following steps: B1. Select a 500mL three-necked round-bottom flask, which is connected to a thermometer, a catheter and a magnetic stirrer. Add 200mL of solvent toluene to the three-necked round-bottom flask, then add 20g of benzidine, 15g of 9-(3-bromophenyl)-9H-carbazole, 5g of cesium acetate and 10g of cesium carbonate in sequence, mix and stir evenly to obtain a reaction system.

[0049] B2. Fill the three-necked round-bottom flask with nitrogen to place the flask in a nitrogen atmosphere. Then transfer the three-necked round-bottom flask to an electric constant temperature water bath, heat it to 120°C, and reflux it for 48 hours at this temperature. After the reaction is completed, cool it to room temperature to obtain the product. The product is extracted three times with a CH2Cl2-H2O system (the mass ratio of CH2Cl2 and H2O is 7:3), and the organic phase is collected; the organic phase is distilled at 115°C to remove the solvent toluene to obtain a solid. The solid is washed with deionized water until neutral, and then vacuum dried at 90°C to constant weight to obtain a solid modified carbazole.

[0050] B3, ethanol and water are mixed in a volume ratio of 3:1 to obtain an organic solvent. 40g of modified carbazole, 5g of hydrated iridium trichloride and 150mL of organic solvent are added to a 500mL three-necked round-bottom flask, and mixed evenly to obtain a reactant. The reactant is placed in a nitrogen atmosphere, accompanied by a stirring speed of 200r / min, and refluxed at 150°C for 20h. After the reaction is completed, it is cooled to room temperature to obtain a mixture. The mixture is allowed to stand at room temperature until no solid is precipitated, and then filtered to obtain a product; the product is rinsed three times with an organic solvent, and then vacuum dried at 70°C to constant weight to obtain a polymer organic fluorescent material.

[0051] B4. Add 15g of calixarene to 80mL of acetone, stir and dissolve to obtain a mother liquor. Add sodium phosphate buffer solution to the mother liquor, adjust the pH value of the mother liquor to 7, and obtain a calixarene mother liquor. Then add 6g of polymer fluorescent material to the calixarene mother liquor to obtain a mixed material; add ultrapure water to the mixed material to make the volume to 100mL, let it stand at room temperature for 2.5h, collect the gel material, and obtain a composite polymer fluorescent material.

[0052] B5. The modified phosphate fluorescent material and the composite polymer fluorescent material prepared in Example 3 were mixed in a mass ratio of 3:1, ground and crushed to 300 meshes to obtain a composite mixed powder. The composite mixed powder was added to a spiral sieving machine for sieving to obtain a phosphate matrix composite fluorescent powder.

[0053] Comparative Example 1 The difference between this comparative example and Example 6 is that, when preparing the modified phosphate fluorescent material, polylactic acid-glycolic acid copolymer is used instead of modified polylactic acid.

[0054] Comparative Example 2 The difference between this comparative example and Example 6 is that ammonium phosphate is used instead of ammonium phosphite when preparing the modified phosphate fluorescent material.

[0055] Comparative Example 3 The difference between this comparative example and Example 6 is that when preparing the composite polymer fluorescent material, 9-(3-bromophenyl)-9H-carbazole is used instead of modified carbazole, which is then reacted with hydrated iridium trichloride to obtain a polymer organic fluorescent material.

[0056] Comparative Example 4 The difference between this comparative example and Example 6 is that the polymer organic fluorescent material is not modified by calixarene, and the polymer organic fluorescent material is used instead of the composite polymer fluorescent material.

[0057] Performance Test: 1. At room temperature, the PLE spectra of the phosphate-based composite phosphors prepared in Examples 4-6 and Comparative Examples 1-4 under 298nm ultraviolet excitation were tested, and the values ​​of the spectral coverage at room temperature, the excitation peak, and the spectral coverage at 275K were tested and recorded.

[0058] 2. The phosphate-based composite phosphors prepared in Examples 4-6 and Comparative Examples 1-4 were heated to 450 K and heated at this temperature for 30 min. The PLE spectra were then detected under 298 nm ultraviolet excitation, and the PLE spectral absorption band range was detected and recorded.

[0059] Table 1. Sample performance test data

[0060] Data analysis: The phosphate matrix composite phosphors prepared in Examples 4-6 of the present invention have multiple excitation spectra, which can expand the application range of the phosphate matrix composite phosphors and improve the luminous efficiency; especially in Example 6, the two excitation spectra are expanded and overlapped to obtain a long-wave spectrum of 235-395nm. However, in Comparative Example 1, when preparing the modified phosphate fluorescent material, polylactic acid-glycolic acid copolymer is used to replace modified polylactic acid, which reduces its own thermal stability. It is manifested that at 275K, the wavelength range of the synthesized phosphate matrix composite phosphor in the excitation spectrum of the inorganic fluorescent material is shortened.

[0061] In Comparative Example 2, when preparing the modified phosphate fluorescent material, ammonium phosphate was used instead of ammonium phosphite, and the trivalent europium ions could not be reduced to divalent europium ions, and the wavelength of a section of the excitation spectrum in the prepared phosphate-based composite phosphor would shift and shorten.

[0062] In Comparative Example 3, when preparing the composite polymer fluorescent material, 9-(3-bromophenyl)-9H-carbazole was used instead of modified carbazole. The polymer organic fluorescent material obtained by combining it with hydrated iridium trichloride contained fewer biphenyl structures, which reduced its own phosphorescence efficiency, which was manifested as a shortening of the wavelength range of the excited red light (specifically 600-611nm).

[0063] In Comparative Example 4, the polymer organic fluorescent material is not modified with calixarene, which reduces its own thermal stability; this is manifested in that at 275K, the wavelength range of the specific spectrum of the synthesized phosphate matrix composite phosphor is shortened.

[0064] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

[0065] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0066] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a phosphate-based composite phosphor, characterized in that: The following steps are involved: S1. Mixing the modified phosphate fluorescent material and the composite polymer fluorescent material in a mass ratio of 2-3:1, grinding and crushing to obtain a composite mixed powder; S2. The composite mixed powder is added into a spiral screening machine for screening to obtain a phosphate matrix composite phosphor.

2. The method for preparing a phosphate-based composite phosphor according to claim 1, characterized in that: In step S1, the method for preparing the modified phosphate fluorescent material comprises the following steps: A1. Dissolve europium oxide in a dilute nitric acid solution, then heat to 115-120° C. and evaporate to dryness to obtain europium nitrate crystals; mix and grind potassium carbonate, magnesium oxide, ammonium phosphite and europium nitrate crystals as raw materials to obtain a ground raw material; A2. The ground raw materials are reacted at 100-200°C for 1-2h, and then heated at 800-900°C for 2-3h to obtain a mixed powder; the mixed powder is naturally cooled to room temperature, and then ground again to obtain fine powder; hydrogen and nitrogen are mixed in a volume ratio of 1:9 to form a mixed gas atmosphere; the fine powder is placed in the mixed gas atmosphere, and is subjected to a constant temperature reaction at 1100-1200°C for 6-8h, and then naturally cooled to room temperature and discharged to obtain a powder crystal, which is the composite inorganic phosphor material K （1-X） MgPO3:XEu 2+ ; A3, mixing polylactic acid-glycolic acid copolymer and acetone, then adding acrylamide, stirring and dissolving to obtain a reactant; the reactant is refluxed at 80-90° C. for 2-3 hours to obtain a product; the product is post-processed to obtain a modified polylactic acid; A4. Add the modified polylactic acid and the composite inorganic fluorescent powder into a twin-screw extruder, and melt-extrude at 185-200° C. to obtain a modified phosphate fluorescent material.

3. The method for preparing a phosphate-based composite phosphor according to claim 2, characterized in that: In step A1, the concentration of the dilute nitric acid solution is 2-3 mol / L, the dosage ratio of europium oxide and dilute nitric acid solution is 3-5 g:100 mL, and the weight ratio of potassium carbonate, magnesium oxide, ammonium phosphite and europium nitrate crystals is 14-28:2-4:40-80:23-46; in step A2, the mixture is placed in a mortar for secondary grinding, and the duration of the secondary grinding is 10-20 min.

4. The method for preparing a phosphate-based composite phosphor according to claim 2, characterized in that: In step A3, the weight ratio of polylactic acid-glycolic acid copolymer, acetone and acrylamide is 20-25:100:5-10; the post-process treatment of the product includes: the product is further evaporated at 80-90° C. to remove the organic solvent acetone to obtain a solid; the solid is washed with deionized water, dried to constant weight, and crushed to 200-300 mesh to obtain a modified polylactic acid; in step A4, the mass ratio of the modified polylactic acid and the composite inorganic fluorescent powder is 1:1-2.

5. The method for preparing a phosphate-based composite phosphor according to claim 1, characterized in that: In step S1, the method for preparing the composite polymer fluorescent material comprises the following steps: B1. Add benzidine, (3-bromophenyl)-9H-carbazole, cesium acetate and cesium carbonate into toluene, mix and stir evenly to obtain a reaction system; B2, placing the reaction system under a nitrogen atmosphere, heating it to 115-120° C., and reflux reacting at this temperature for 24-48 hours. After the reaction is completed, cooling it to room temperature to obtain a product; the product is post-processed to obtain a solid modified carbazole; B3, the modified carbazole, hydrated iridium trichloride and organic solvent are mixed to obtain a reactant; the reactant is placed in a nitrogen atmosphere, refluxed at 130-150° C. for 20-24 hours, and cooled to room temperature after the reaction to obtain a mixture; the mixture is post-processed to obtain a polymer organic fluorescent material; B4. Mix the calixarene mother liquor and the polymer organic fluorescent material to obtain a mixed material; add ultrapure water to the mixed material to make up to volume, let it stand at room temperature for 2-3 hours, collect the gel material, and obtain a composite polymer fluorescent material.

6. The method for preparing a phosphate-based composite phosphor according to claim 5, characterized in that: In step B1, the amount ratio of toluene, benzidine, (3-bromophenyl)-9H-carbazole, cesium acetate and cesium carbonate is 200mL:18-20g:10-15g:3-5g:5-10g; in step B2, the post-processing steps of the product include: the product is extracted three times by a CH2Cl2-H2O system, and the organic phase is collected; the organic phase is distilled at 112-115°C to remove the solvent toluene to obtain a solid; the solid is washed with deionized water to neutrality, and then vacuum dried at 80-90°C to constant weight to obtain a solid modified carbazole.

7. The method for preparing a phosphate-based composite phosphor according to claim 5, characterized in that: In step B3, the organic solvent is obtained by mixing ethanol and water in a volume ratio of 3:1; the usage ratio of the modified carbazole, hydrated iridium trichloride and the organic solvent is 30-40g:2-5g:125-150mL; the post-processing steps of the mixture include: the mixture is allowed to stand at room temperature until solids no longer precipitate, and then filtered to obtain a product; the product is eluted three times with an organic solvent, and then vacuum dried at 60-70°C to constant weight to obtain a polymer organic fluorescent material.

8. The method for preparing a phosphate-based composite phosphor according to claim 5, characterized in that: In step B4, the calixarene mother liquor is prepared by the following steps: mixing calixarene and acetone to obtain a mother liquor; adding sodium phosphate buffer solution dropwise to the mother liquor, adjusting the pH value of the mother liquor to 6-7, and obtaining a calixarene mother liquor; the amount ratio of calixarene, acetone and polymer organic fluorescent material is 10-15g:60-80mL:5-6g.

9. A phosphate-based composite phosphor, characterized in that: The phosphate-based composite phosphor is prepared by the method for preparing a phosphate-based composite phosphor according to any one of claims 1 to 8.

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