Preparation method of easily-dispersed infrared photoluminescence rare earth pigment preparation and preparation

Abstract

The preparation method comprises the following steps: S1, preparing a rare earth solution, S2, preparing a tetraethoxy silane solution, S3, preparing an infrared photoluminescence rare earth pigment, slowly adding the rare earth solution into the tetraethoxy silane solution, uniformly stirring, and cooling to room temperature to obtain the infrared photoluminescence rare earth pigment. And then pumping the mixture into one or more gel containers, putting the gel containers into a drying oven for drying, and putting the dried gel into a calcining furnace for calcining to obtain the infrared photoluminescence rare earth pigment. And S4, preparing an infrared photoluminescence rare earth pigment preparation, namely crushing an infrared photoluminescence rare earth pigment, uniformly stirring and mixing the crushed infrared photoluminescence rare earth pigment with the carrier and the solvent to obtain premixed slurry, grinding the premixed slurry by using a ball mill, and filtering and drying after confirming that the pigment is coated by the carrier, thereby obtaining the easily-dispersed infrared photoluminescence rare earth pigment preparation. The polymer has better dispersity, can be prepared into products such as printing ink, coating and plastic, and is good in physical stability and simple in identification method.

Description

Technical Field

[0001] This invention belongs to the field of pigment production technology, and in particular relates to a method for preparing easily dispersible infrared photoluminescent rare earth pigments and the prepared products. Background Technology

[0002] Counterfeiting and imitation are illegal and criminal activities that have existed throughout history and across the world. Countries worldwide have been impacted and harmed by counterfeit products. Combating counterfeiting has become a global effort.

[0003] This invention provides a method for concealed anti-counterfeiting. By utilizing the special light-reflecting ability of rare earth elements, they are made into infrared photoluminescent rare earth pigments, which are then printed on currency, checks, passports, and other items, or added to plastics and other packaging materials. The authenticity of the products can be verified by visually distinguishing them through infrared light irradiation or by detecting their characteristic spectra through photoelectric detectors.

[0004] The main synthesis methods for infrared photoluminescent rare earth pigments include the high-temperature solid-state reaction method and the sol-gel method. The high-temperature solid-state reaction method synthesizes photoluminescent rare earth pigments by causing a solid-state reaction of reactants at high temperatures through a hot-melt process. This method is simple but requires high-temperature equipment, and the resulting product has high density, high hardness, and is not easy to grind. Due to the high specific gravity of the pigment, it is prone to separation during ink production, often causing printing problems. The sol-gel method, on the other hand, is a wet chemical method for preparing upconversion luminescent materials. It uses active compounds such as tetraethoxysilane as precursors, mixes them in water, and performs hydrolysis and condensation reactions to form a sol. Simultaneously, rare earth elements are dissolved and added to the transparent sol system. After static aging, the resulting silica particles slowly polymerize with the rare earth compounds, forming a three-dimensional network structure gel. Finally, the gel is dried, sintered, and solidified to prepare the rare earth luminescent material. The advantage of this method is that it can be carried out at lower temperatures, and the crystals produced by the sol-gel process are slightly superior. However, it still presents the problem of poor dispersion when used in inks, coatings, or plastics. Summary of the Invention

[0005] The purpose of this invention is to provide a method and preparation of an easily dispersible infrared photoluminescent rare earth pigment, which has good dispersibility and can be made into products such as inks, coatings and plastics. It can be combined with various substrates as an anti-counterfeiting mark. Under infrared light irradiation of a specific wavelength, it can present an anti-counterfeiting image. It has good physical stability and a simple identification method.

[0006] To achieve the above-mentioned technical objectives and related technical objectives, this invention provides a method for preparing easily dispersible infrared photoluminescent rare earth pigments, the steps of which include: S1. To prepare a rare earth solution, add deionized water to the reactor, then slowly add trifluoroacetic acid while stirring, control the material temperature in the reactor to be below 30°C, and then slowly add one or more rare earth compounds. After stirring and dissolving evenly, a rare earth solution is obtained. S2. To prepare a tetraethoxysilane solution, add deionized water to another reaction vessel, then slowly add ethanol and dimethylformamide and stir until evenly mixed. Then slowly add trifluoroacetic acid and stir, controlling the material temperature in the reaction vessel to be below 30°C. Finally, add tetraethoxysilane and stir until evenly dissolved to obtain a tetraethoxysilane solution. S3. To prepare infrared photoluminescent rare earth pigment, slowly add the rare earth solution to the tetraethoxysilane solution and stir to mix evenly. Control the reaction temperature below 30℃. Then pump the mixture into one or more gel containers and place the gel containers in an oven. Bake at 45-50℃ for 4-6 days and at 65-75℃ for 4-6 days to gel the mixture. Then raise the temperature to 170-180℃ and bake for 2-3 days to dry the gel. Then place the dried gel in a calcining furnace and calcine it. First, raise the temperature to 500-700℃ at a rate of 1℃ / min and hold for 1-3 hours. Then raise the temperature to 800-1000℃ at a rate of 1℃ / min. Finally, slowly cool the calcining furnace to obtain the crude infrared photoluminescent rare earth pigment. Crush the crude infrared photoluminescent rare earth pigment using an ultrafine pulverizer and then sieve it to obtain infrared photoluminescent rare earth pigment with a relatively coarse particle size. S4. Preparation of infrared photoluminescent rare earth pigment: The infrared photoluminescent rare earth pigment obtained in step S3 is stirred and mixed evenly with the carrier and solvent to obtain a premixed slurry. The premixed slurry is then ground using a ball mill. After confirming that the carrier has completely coated the pigment, the material is filtered and the filter is dried to obtain an easily dispersible infrared photoluminescent rare earth pigment preparation.

[0007] In one example of the preparation method of the easily dispersible infrared photoluminescent rare earth pigment of the present invention, the weight parts of each component in the rare earth solution are: 14-20 parts of deionized water, 25-35 parts of trifluoroacetic acid, and 43-50 parts of rare earth compound.

[0008] In one example of the preparation method of the easily dispersible infrared photoluminescent rare earth pigment of the present invention, the weight parts of each component in the tetraethoxysilane solution are: 6-13 parts of deionized water, 40-48 parts of ethanol, 4-7 parts of dimethylformamide, 5-8 parts of trifluoroacetic acid, and 37-44 parts of tetraethoxysilane.

[0009] In one example of the preparation method of the easily dispersible infrared photoluminescent rare earth pigment of the present invention, the rare earth compound is a lanthanide compound.

[0010] In one example of the preparation method of the easily dispersible infrared photoluminescent rare earth pigment of the present invention, the lanthanide elements include lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, or yttrium.

[0011] In one example of the preparation method of the easily dispersible infrared photoluminescent rare earth pigment of the present invention, the carrier is one of nitrocellulose resin, cellulose acetate butyrate resin, polyvinyl butyral resin, chloroacetic acid resin, aldehyde resin, low-density polyethylene, and low-density polyethylene wax.

[0012] In one example of the preparation method of the easily dispersible infrared photoluminescent rare earth pigment of the present invention, the solvent is one or both of butyl acetate and water.

[0013] In one example of the preparation method of the easily dispersible infrared photoluminescent rare earth pigment of the present invention, the mass ratio of the infrared photoluminescent rare earth pigment to the carrier is 1:(0.5-3).

[0014] In one example of the preparation method of the easily dispersible infrared photoluminescent rare earth pigment of the present invention, step S4 further includes pretreatment of the infrared photoluminescent rare earth pigment, the steps of which include: grinding the infrared photoluminescent rare earth pigment with water in a sand mill for 0.5 to 2 hours, and controlling the grinding temperature to be below 40°C.

[0015] In one example of the preparation method of the easily dispersible infrared photoluminescent rare earth pigment of the present invention, step S4 includes: grinding the premixed slurry in a ball mill, controlling the grinding temperature to be below 45°C, grinding time to be 0.5 to 2 hours, confirming that the carrier has coated the pigment, filtering the material, and drying the filter material, controlling the drying temperature to be 70 to 80°C.

[0016] The present invention also provides an easily dispersible infrared photoluminescent rare earth pigment preparation prepared by the preparation method of the aforementioned easily dispersible infrared photoluminescent rare earth pigment preparation.

[0017] The beneficial effects of this invention are as follows: 1. This invention uses a ball mill to grind infrared photoluminescent rare earth pigment particles to nanoscale fineness through high shear force and high impact force grinding, and the particles are then encapsulated and protected by a softened carrier to prevent pigment flocculation. Afterward, the dispersed infrared photoluminescent rare earth pigment can continue to be impacted and refined by the grinding media in the ball mill to obtain finer and more uniform pigment particles, forming an infrared photoluminescent rare earth pigment preparation. This greatly improves its dispersibility and makes it more convenient to use. 2. Infrared photoluminescent rare earth pigments, prepared using different carriers, can be applied to various applications. For example, infrared photoluminescent rare earth pigments made with cellulose acetate butyrate resin, polyvinyl butyral resin, vinyl chloride resin, or aldehyde resin can be used to prepare solvent-based coatings; those made with nitrocellulose resin, vinyl chloride resin, or polyvinyl butyral resin can be used to prepare solvent-based inks; and those made with low-density polyethylene or low-density polyethylene wax can be used to prepare plastics. This greatly expands the application range of infrared photoluminescent rare earth pigments and increases customer acceptance. 3. Infrared photoluminescent rare earth pigments can be combined with various substrates as anti-counterfeiting labels. These labels are colorless and invisible under sunlight, undetectable to the naked eye, strong light, and ultraviolet light. Under specific wavelengths of infrared light, they reveal an anti-counterfeiting image. They exhibit good physical stability, are easy to identify, and are technologically advanced, making them difficult to counterfeit. Detailed Implementation

[0018] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other. It should also be understood that the terminology used in the embodiments of the present invention is for describing specific implementation schemes and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0019] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of the invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to the methods, devices, and materials in the embodiments of the present invention.

[0020] This invention provides a method for preparing easily dispersible infrared photoluminescent rare earth pigments, the steps of which include: S1. To prepare a rare earth solution, add deionized water to the reactor, then slowly add trifluoroacetic acid while stirring, control the material temperature in the reactor to be below 30°C, and then slowly add one or more rare earth compounds. After stirring and dissolving evenly, a rare earth solution is obtained. S2. To prepare a tetraethoxysilane solution, add deionized water to another reaction vessel, then slowly add ethanol and dimethylformamide and stir until evenly mixed. Then slowly add trifluoroacetic acid and stir, controlling the material temperature in the reaction vessel to be below 30°C. Finally, add tetraethoxysilane and stir until evenly dissolved to obtain a tetraethoxysilane solution. S3. To prepare infrared photoluminescent rare earth pigment, slowly add the rare earth solution to the tetraethoxysilane solution and stir to mix evenly. Control the reaction temperature below 30℃. Then pump the mixture into one or more gel containers and place the gel containers in an oven. Bake at 45-50℃ for 4-6 days and at 65-75℃ for 4-6 days to gel the mixture. Then raise the temperature to 170-180℃ and bake for 2-3 days to dry the gel. Then place the dried gel in a calcining furnace and calcine it. First, raise the temperature to 500-700℃ at a rate of 1℃ / min and hold for 1-3 hours. Then raise the temperature to 800-1000℃ at a rate of 1℃ / min. Finally, slowly cool the calcining furnace to obtain the crude infrared photoluminescent rare earth pigment. Crush the crude infrared photoluminescent rare earth pigment using an ultrafine pulverizer and then sieve it to obtain infrared photoluminescent rare earth pigment with a relatively coarse particle size. S4. Preparation of infrared photoluminescent rare earth pigment: The infrared photoluminescent rare earth pigment obtained in step S3 is stirred and mixed evenly with the carrier and solvent to obtain a premixed slurry. The premixed slurry is then ground using a ball mill. After confirming that the carrier has completely coated the pigment, the material is filtered and the filter is dried to obtain an easily dispersible infrared photoluminescent rare earth pigment preparation.

[0021] In one example of the preparation method of the easily dispersible infrared photoluminescent rare earth pigment of the present invention, the weight parts of each component in the rare earth solution are: 14-20 parts of deionized water, 25-35 parts of trifluoroacetic acid, and 43-50 parts of rare earth compound. The weight parts of each component in the tetraethoxysilane solution are: 6-13 parts of deionized water, 40-48 parts of ethanol, 4-7 parts of dimethylformamide, 5-8 parts of trifluoroacetic acid, and 37-44 parts of tetraethoxysilane.

[0022] In one example of the preparation method of the easily dispersible infrared photoluminescent rare earth pigment of the present invention, the rare earth compound is a lanthanide compound. The lanthanide elements include lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), scandium (Sc), or yttrium (Y).

[0023] In one example of the preparation method of the easily dispersible infrared photoluminescent rare earth pigment of the present invention, the carrier is one of nitrocellulose resin, cellulose acetate butyrate resin, polyvinyl butyral resin, chloroacetic acid resin, aldehyde resin, low-density polyethylene, and low-density polyethylene wax. The solvent is one or both of butyl acetate and water.

[0024] In one example of the preparation method of the easily dispersible infrared photoluminescent rare earth pigment of the present invention, the mass ratio of the infrared photoluminescent rare earth pigment to the carrier is 1:(0.5-3).

[0025] In one example of the preparation method of the easily dispersible infrared photoluminescent rare earth pigment of the present invention, step S4 further includes pretreatment of the infrared photoluminescent rare earth pigment, the steps of which include: grinding the infrared photoluminescent rare earth pigment with water in a sand mill for 0.5 to 2 hours, and controlling the grinding temperature to be below 40°C.

[0026] In one example of the preparation method of the easily dispersible infrared photoluminescent rare earth pigment of the present invention, step S4 includes: grinding the premixed slurry in a ball mill, controlling the grinding temperature to be below 45°C, grinding time to be 0.5 to 2 hours, confirming that the carrier has coated the pigment, filtering the material, and drying the filter material, controlling the drying temperature to be 70 to 80°C.

[0027] The present invention also provides an easily dispersible infrared photoluminescent rare earth pigment preparation prepared by the preparation method of the aforementioned easily dispersible infrared photoluminescent rare earth pigment preparation.

[0028] The present invention will be further described below through several embodiments. It should be noted that, unless otherwise specified, the materials, reagents and equipment used in the embodiments can all be purchased through commercial means.

[0029] Example 1: A method for preparing an easily dispersible infrared photoluminescent rare earth pigment, comprising the following steps: S1. To prepare a rare earth solution, add 208g of deionized water to a reaction vessel, then slowly add 500g of trifluoroacetic acid while stirring. Control the material temperature in the reaction vessel to be below 30℃. Then, slowly add 14.9g of erbium acetate, 597.2g of lanthanum acetate, and 151.2g of ytterbium acetate using a feeding funnel. Rinse the feeding funnel with 80g of deionized water and stir until dissolved to obtain a rare earth solution.

[0030] S2. To prepare a tetraethoxysilane solution, add 144g of deionized water to another reaction vessel, then slowly add 736g of ethanol and 93.4g of dimethylformamide and stir until homogeneous. Then slowly add 109.6g of trifluoroacetic acid and stir, controlling the material temperature in the reaction vessel to be below 30℃. Finally, add 665.6g of tetraethoxysilane and stir until homogeneous to obtain a tetraethoxysilane solution.

[0031] S3. To prepare infrared photoluminescent rare earth pigment, the rare earth solution was slowly added to the tetraethoxysilane solution and stirred until homogeneous. The reaction temperature was controlled below 30°C. The mixture was then pumped into 33 gel containers and placed in an oven. The containers were baked at 50°C for 5 days, then at 70°C for 5 days, and then at 175°C for 2 days to dry the gel. The dried gel was then placed in a calcining furnace and calcined. The temperature was first increased to 600°C at a rate of 1°C / min and held for 3 hours. Then the temperature was increased to 900°C at a rate of 1°C / min. Finally, the calcining furnace was slowly cooled. The calcined product was pulverized using an ultrafine pulverizer and sieved to obtain the infrared photoluminescent rare earth pigment.

[0032] S4. Preparation of Infrared Photoluminescent Rare Earth Pigment: 500g of deionized water and 80g of low-density polyethylene were added to a premixing tank. Stirring was started at low speed, and 160g of the infrared photoluminescent rare earth pigment was slowly added simultaneously. The stirring speed was then increased for 10 minutes to obtain a uniformly mixed premixed slurry. The premixed slurry was then transferred to a ball mill for grinding, with the temperature controlled below 45℃, for 2 hours. Sampling and testing confirmed that the pigment was completely coated with the carrier. Water was added, the mixture was discharged, filtered, and dried at 80℃ to obtain an easily dispersible infrared photoluminescent rare earth pigment preparation. Irradiation with a 975nm, 50mW infrared laser source showed that the preparation emitted a distinct green light. Plastic products were made from this preparation, and their emission spectra were detected using a photodetector. The spectra were unique to this rare earth pigment, with values ​​at 519nm (weak) and 540nm (strong).

[0033] Example 2: A method for preparing an easily dispersible infrared photoluminescent rare earth pigment, comprising the following steps: S1. To prepare a rare earth solution, add 160g of deionized water to a reaction vessel, then slowly add 430g of trifluoroacetic acid while stirring. Control the material temperature in the reaction vessel to be below 30℃. Then, slowly add 18.3g of erbium acetate, 582.6g of lanthanum acetate, and 197.6g of ytterbium acetate using a feeding funnel. Rinse the feeding funnel with 80g of deionized water and stir until dissolved to obtain a rare earth solution.

[0034] S2. To prepare a tetraethoxysilane solution, add 110g of deionized water to another reaction vessel, then slowly add 680g of ethanol and 108.1g of dimethylformamide and stir until homogeneous. Then slowly add 118.7g of trifluoroacetic acid and stir, controlling the material temperature in the reaction vessel to be below 30℃. Finally, add 695.3g of tetraethoxysilane and stir until homogeneous to obtain a tetraethoxysilane solution.

[0035] S3. To prepare infrared photoluminescent rare earth pigment, the rare earth solution was slowly added to the tetraethoxysilane solution and stirred until homogeneous. The reaction temperature was controlled below 30°C. The mixture was then pumped into 33 gel containers and placed in an oven. The containers were baked at 50°C for 5 days, then at 70°C for 5 days, and then at 175°C for 2 days to dry the gel. The dried gel was then placed in a calcining furnace and calcined. The temperature was first increased to 700°C at a rate of 1°C / min and held for 3 hours. Then the temperature was increased to 1000°C at a rate of 1°C / min. Finally, the calcining furnace was slowly cooled. The calcined product was pulverized using an ultrafine pulverizer and sieved to obtain the infrared photoluminescent rare earth pigment.

[0036] S4. Preparation of Infrared Photoluminescent Rare Earth Pigment: In a premixing tank, add 500g of deionized water and 100g of low-density polyethylene wax. Stir at low speed while slowly adding 100g of the infrared photoluminescent rare earth pigment. Then increase the stirring speed and stir for 20 minutes to obtain a uniformly mixed premixed slurry. Transfer the premixed slurry to a ball mill for grinding, controlling the temperature below 45℃, and grind for 1 hour. Sampling and testing confirmed that the pigment was completely coated with the carrier. Water was added, the mixture was discharged, filtered, and dried at 80℃ to obtain an easily dispersible infrared photoluminescent rare earth pigment preparation. Irradiated with a 975nm, 50mW infrared laser source, this preparation clearly emitted green light. This preparation was made into a plastic product, and its emission spectrum was detected using a photodetector. It exhibited a unique spectrum characteristic of this rare earth pigment, with values ​​at 519nm (weak) and 540nm (strong).

[0037] Example 3: A method for preparing an easily dispersible infrared photoluminescent rare earth pigment, comprising the following steps: S1. To prepare a rare earth solution, add 250g of deionized water to a reaction vessel, then slowly add 570g of trifluoroacetic acid while stirring. Control the material temperature in the reaction vessel to be below 30℃. Then, slowly add 16.1g of erbium acetate, 550.4g of lanthanum acetate, and 160.3g of ytterbium acetate using a feeding funnel. Rinse the feeding funnel with 80g of deionized water and stir until dissolved to obtain a rare earth solution.

[0038] S2. To prepare a tetraethoxysilane solution, add 192g of deionized water to another reaction vessel, then slowly add 730g of ethanol and 83.5g of dimethylformamide and stir until homogeneous. Then slowly add 98.6g of trifluoroacetic acid and stir, keeping the temperature of the material in the reaction vessel below 30℃. Finally, add 635.2g of tetraethoxysilane and stir until homogeneous to obtain a tetraethoxysilane solution.

[0039] S3. To prepare infrared photoluminescent rare earth pigment, the rare earth solution was slowly added to the tetraethoxysilane solution and stirred until homogeneous. The reaction temperature was controlled below 30°C. The mixture was then pumped into 33 gel containers and placed in an oven. The containers were baked at 50°C for 5 days, then at 70°C for 5 days, and then at 175°C for 2 days to dry the gel. The dried gel was then placed in a calcining furnace and calcined. The temperature was first increased to 500°C at a rate of 1°C / min and held for 3 hours. Then the temperature was increased to 800°C at a rate of 1°C / min. Finally, the calcining furnace was slowly cooled. The calcined product was pulverized using an ultrafine pulverizer and sieved to obtain the infrared photoluminescent rare earth pigment.

[0040] S4. Preparation of Infrared Photoluminescent Rare Earth Pigment: In a premixing tank, add 500g of deionized water and start stirring at low speed while slowly adding 50g of infrared photoluminescent rare earth pigment. Then increase the stirring speed for 10 minutes to obtain a premixed color paste. Transfer the premixed color paste to a sand mill and grind for 2 hours, controlling the grinding temperature below 40℃. The particle size d50 is measured to be 382nm using a laser particle size analyzer. Transfer the ground color paste back to the premixing tank and start stirring at low speed. Add 150g of chloroacetic acid resin and 20g of butyl acetate. Then increase the stirring speed for 5 minutes to obtain a uniformly mixed premixed slurry. Transfer the premixed slurry to a ball mill for grinding, controlling the temperature below 45℃, and grind for 1 hour. Take a sample for testing to confirm that the pigment has been completely coated with the carrier. Add water and discharge the material, filter the preparation, and dry at 70℃ to obtain an easily dispersible infrared photoluminescent rare earth pigment preparation. Irradiation with a 975nm, 50mW infrared laser source revealed that the prepared material emitted a distinct green light. When this material was made into a coating, its emission spectrum was detected using a photodetector, revealing a unique spectrum characteristic of this rare earth pigment, with values ​​at 519nm (weak) and 540nm (strong).

[0041] Example 4: A method for preparing an easily dispersible infrared photoluminescent rare earth pigment, comprising the following steps: S1. To prepare a rare earth solution, add 220g of deionized water to a reaction vessel, then slowly add 540g of trifluoroacetic acid while stirring. Control the material temperature in the reaction vessel to be below 30℃. Then, slowly add 11.3g of europium acetate, 588.4g of yttrium acetate, and 220.9g of ytterbium acetate using a feeding funnel. Rinse the feeding funnel with 80g of deionized water and stir until dissolved to obtain a rare earth solution.

[0042] S2. To prepare a tetraethoxysilane solution, add 110g of deionized water to another reaction vessel, then slowly add 700g of ethanol and 110.6g of dimethylformamide and stir until homogeneous. Then slowly add 117.5g of trifluoroacetic acid and stir, controlling the material temperature in the reaction vessel to be below 30℃. Finally, add 735.9g of tetraethoxysilane and stir until homogeneous to obtain a tetraethoxysilane solution.

[0043] S3. To prepare infrared photoluminescent rare earth pigment, the rare earth solution was slowly added to the tetraethoxysilane solution and stirred until homogeneous. The reaction temperature was controlled below 30°C. The mixture was then pumped into 34 gel containers and placed in an oven. The containers were baked at 50°C for 5 days, then at 70°C for 5 days, and then at 175°C for 2 days to dry the gel. The dried gel was then placed in a calcining furnace and calcined. The temperature was first increased to 700°C at a rate of 1°C / min and held for 3 hours. Then the temperature was increased to 1000°C at a rate of 1°C / min. Finally, the calcining furnace was slowly cooled. The calcined product was pulverized using an ultrafine pulverizer and sieved to obtain the infrared photoluminescent rare earth pigment.

[0044] S4. Preparation of Infrared Photoluminescent Rare Earth Pigment: In a premixing tank, add 500g of deionized water and 120g of low-density polyethylene wax. Stir at low speed while slowly adding 80g of the infrared photoluminescent rare earth pigment. Then increase the stirring speed and stir for 10 minutes to obtain a uniformly mixed premixed slurry. Transfer the premixed slurry to a ball mill for grinding, controlling the temperature below 45℃, and grind for 1 hour. Sampling and testing confirm that the pigment is completely coated with the carrier. Add water, discharge the material, filter the preparation, and dry at 80℃ to obtain an easily dispersible infrared photoluminescent rare earth pigment preparation. Irradiated with a 975nm, 50mW infrared laser source, this preparation clearly emits red light. This preparation was made into a plastic product, and its emission spectrum was detected using a photodetector. It exhibits a unique spectrum characteristic of this rare earth pigment, with values ​​at 590nm (weak) and 612nm (strong).

[0045] Example 5: A method for preparing an easily dispersible infrared photoluminescent rare earth pigment, comprising the following steps: S1. To prepare a rare earth solution, add 190g of deionized water to a reaction vessel, then slowly add 436g of trifluoroacetic acid while stirring. Control the material temperature in the reaction vessel to be below 30℃. Then, slowly add 15.9g of europium acetate, 534.2g of yttrium acetate, and 143.3g of ytterbium acetate using a feeding funnel. Rinse the feeding funnel with 80g of deionized water, and stir until dissolved to obtain a rare earth solution.

[0046] S2. To prepare a tetraethoxysilane solution, add 180g of deionized water to another reaction vessel, then slowly add 653g of ethanol and 108.6g of dimethylformamide and stir until homogeneous. Then slowly add 119.5g of trifluoroacetic acid and stir, controlling the material temperature in the reaction vessel to be below 30℃. Finally, add 675.3g of tetraethoxysilane and stir until homogeneous to obtain a tetraethoxysilane solution.

[0047] S3. To prepare infrared photoluminescent rare earth pigment, the rare earth solution was slowly added to the tetraethoxysilane solution and stirred until homogeneous. The reaction temperature was controlled below 30°C. The mixture was then pumped into 34 gel containers and placed in an oven. The containers were baked at 50°C for 5 days, then at 70°C for 5 days, and then at 175°C for 2 days to dry the gel. The dried gel was then placed in a calcining furnace and calcined. The temperature was first increased to 600°C at a rate of 1°C / min and held for 3 hours. Then the temperature was increased to 900°C at a rate of 1°C / min. Finally, the calcining furnace was slowly cooled. The calcined product was pulverized using an ultrafine pulverizer and sieved to obtain the infrared photoluminescent rare earth pigment.

[0048] S4. Preparation of Infrared Photoluminescent Rare Earth Pigment: In a premixing tank, add 500g deionized water, 100g polyvinyl butyral resin, and 22g butyl acetate. Start stirring at low speed while slowly adding 100g of the infrared photoluminescent rare earth pigment. Then increase the stirring speed and stir for 10 minutes to obtain a uniformly mixed premixed slurry. Transfer the premixed slurry to a ball mill for grinding, controlling the temperature below 45℃, and grind for 30 minutes. Sampling and testing confirm that the pigment has been completely coated with the carrier. Add water, discharge the material, filter the preparation, and dry at 70℃ to obtain an easily dispersible infrared photoluminescent rare earth pigment preparation. Irradiate with a 975nm, 50mW infrared laser source; this preparation clearly emits red light. This preparation is made into an ink, and its emission spectrum is detected using a photodetector. It exhibits a unique spectrum characteristic of this rare earth pigment, with values ​​at 590nm (weak) and 612nm (strong).

[0049] Example 6: A method for preparing an easily dispersible infrared photoluminescent rare earth pigment, comprising the following steps: S1. To prepare a rare earth solution, add 210g of deionized water to a reaction vessel, then slowly add 493g of trifluoroacetic acid while stirring. Control the material temperature in the reaction vessel to be below 30℃. Then, slowly add 17.9g of europium acetate, 600.1g of yttrium acetate, and 147.9g of ytterbium acetate using a feeding funnel. Rinse the feeding funnel with 80g of deionized water and stir until dissolved to obtain a rare earth solution.

[0050] S2. To prepare a tetraethoxysilane solution, add 200g of deionized water to another reaction vessel, then slowly add 781g of ethanol and 106.3g of dimethylformamide and stir until homogeneous. Then slowly add 124.1g of trifluoroacetic acid and stir, controlling the material temperature in the reaction vessel to be below 30℃. Finally, add 699.2g of tetraethoxysilane and stir until homogeneous to obtain a tetraethoxysilane solution.

[0051] S3. To prepare infrared photoluminescent rare earth pigment, the rare earth solution was slowly added to the tetraethoxysilane solution and stirred until homogeneous. The reaction temperature was controlled below 30°C. The mixture was then pumped into 33 gel containers and placed in an oven. The containers were baked at 45°C for 6 days and then at 65°C for 6 days to gel the mixture. The temperature was then raised to 170°C and baked for 3 days to dry the gel. The dried gel was then placed in a calcining furnace and calcined. The temperature was first raised to 500°C at a rate of 1°C / min and held for 1 hour. Then the temperature was raised to 800°C at a rate of 1°C / min. Finally, the calcining furnace was slowly cooled. The calcined product was pulverized using an ultrafine pulverizer and sieved to obtain the infrared photoluminescent rare earth pigment.

[0052] S4. Preparation of Infrared Photoluminescent Rare Earth Pigment: In a premixing tank, add 500g of deionized water and start stirring at low speed while slowly adding 100g of infrared photoluminescent rare earth pigment. Then increase the stirring speed for 10 minutes to obtain a premixed color paste. Transfer the premixed color paste to a sand mill and grind for 30 minutes, controlling the grinding temperature below 40℃. The particle size d50 is measured to be 453nm using a laser particle size analyzer. Transfer the ground color paste back to the premixing tank and start stirring at low speed. Add 100g of chloroacetic acid resin and 30g of butyl acetate. Then increase the stirring speed for 5 minutes to obtain a uniformly mixed premixed slurry. Transfer the premixed slurry to a ball mill for grinding, controlling the temperature below 45℃, and grind for 2 hours. Take a sample for testing to confirm that the pigment has been completely coated with the carrier. Add water and discharge the material, filter the preparation, and dry at 70℃ to obtain an easily dispersible infrared photoluminescent rare earth pigment preparation. Irradiation with a 975nm, 50mW infrared laser source revealed that the prepared material emitted a distinct red light. When this material was made into a coating, its emission spectrum was detected using a photodetector, revealing a unique spectrum characteristic of this rare earth pigment, located at 590nm (weak) and 612nm (strong).

[0053] The easily dispersible infrared photoluminescent rare earth pigment preparation of this invention has good dispersibility and can be made into products such as inks, coatings and plastics. It can be combined with a variety of substrates as an anti-counterfeiting mark. Under infrared light of a specific wavelength, it can present an anti-counterfeiting image. It has good physical stability and simple identification method.

[0054] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preparing an easily dispersible infrared photoluminescent rare earth pigment, characterized in that the steps include... include: S1. To prepare a rare earth solution, add deionized water to the reactor, then slowly add trifluoroacetic acid while stirring, control the material temperature in the reactor to be below 30°C, and then slowly add one or more rare earth compounds. After stirring and dissolving evenly, a rare earth solution is obtained. S2. To prepare a tetraethoxysilane solution, add deionized water to another reaction vessel, then slowly add ethanol and dimethylformamide and stir until evenly mixed. Then slowly add trifluoroacetic acid and stir, controlling the material temperature in the reaction vessel to be below 30°C. Finally, add tetraethoxysilane and stir until evenly dissolved to obtain a tetraethoxysilane solution. S3. To prepare infrared photoluminescent rare earth pigment, slowly add the rare earth solution to the tetraethoxysilane solution and stir to mix evenly. Control the reaction temperature below 30℃. Then pump the mixture into one or more gel containers and place the gel containers in an oven. Bake at 45-50℃ for 4-6 days and at 65-75℃ for 4-6 days to gel the mixture. Then raise the temperature to 170-180℃ and bake for 2-3 days to dry the gel. Then place the dried gel in a calcining furnace and calcine it. First, raise the temperature to 500-700℃ at a rate of 1℃ / min and hold for 1-3 hours. Then raise the temperature to 800-1000℃ at a rate of 1℃ / min. Finally, slowly cool the calcining furnace to obtain the crude infrared photoluminescent rare earth pigment. Crush the crude infrared photoluminescent rare earth pigment using an ultrafine pulverizer and then sieve it to obtain infrared photoluminescent rare earth pigment with a relatively coarse particle size. S4. Prepare infrared photoluminescent rare earth pigment: Mix the infrared photoluminescent rare earth pigment obtained in step S3 with the carrier and solvent to obtain a premixed slurry. Then, grind the premixed slurry with a ball mill. After confirming that the carrier has coated the pigment, filter the material and dry the filter to obtain an easily dispersible infrared photoluminescent rare earth pigment.

2. The method for preparing the easily dispersible infrared photoluminescent rare earth pigment as described in claim 1, characterized in that, The weight proportions of each component in the rare earth solution are: 14-20 parts deionized water, 25-35 parts trifluoroacetic acid, and 43-50 parts rare earth compounds.

3. The method for preparing the easily dispersible infrared photoluminescent rare earth pigment as described in claim 1, wherein the weight parts of each component in the tetraethoxysilane solution are: 6-13 parts of deionized water, 40-48 parts of ethanol, 4-7 parts of dimethylformamide, 5-8 parts of trifluoroacetic acid, and 37-44 parts of tetraethoxysilane.

4. The method for preparing easily dispersible infrared photoluminescent rare earth pigments as described in claim 1, wherein the rare earth compound is a lanthanide compound.

5. The method for preparing easily dispersible infrared photoluminescent rare earth pigments as described in claim 4, wherein the lanthanide elements include lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, or yttrium.

6. The method for preparing easily dispersible infrared photoluminescent rare earth pigments as described in claim 1, wherein the carrier is one of nitrocellulose resin, cellulose acetate butyrate resin, polyvinyl butyral resin, chloroacetic acid resin, aldehyde resin, low-density polyethylene, and low-density polyethylene wax, and the solvent is one or both of butyl acetate and water.

7. The method for preparing the easily dispersible infrared photoluminescent rare earth pigment as described in claim 1, wherein the mass ratio of the infrared photoluminescent rare earth pigment to the carrier is 1:(0.5-3).

8. The method for preparing the easily dispersible infrared photoluminescent rare earth pigment as described in claim 1, wherein step S4 further includes pretreatment of the infrared photoluminescent rare earth pigment, the steps comprising: The infrared photoluminescent rare earth pigment was ground with water in a sand mill for 0.5 to 2 hours, and the grinding temperature was controlled to be below 40°C.

9. The method for preparing the easily dispersible infrared photoluminescent rare earth pigment as described in claim 1, wherein step S4 comprises: The premixed slurry is ground in a ball mill, with the grinding temperature controlled below 45℃ and the grinding time being 0.5 to 2 hours. After confirming that the carrier has coated the pigment, the material is filtered and the filter is dried, with the drying temperature controlled at 70 to 80℃.

10. A readily dispersible infrared photoluminescent rare earth pigment preparation, characterized in that, It is prepared by the preparation method of the easily dispersible infrared photoluminescent rare earth pigment according to any one of claims 1 to 9.