Dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink and preparation method thereof

Abstract

The present invention discloses a method for preparing a dual-mode orthogonal multicolor fluorescent security and anti-counterfeiting ink, belonging to the field of optical anti-counterfeiting technology, comprising: step 1: preparing core nanocrystals by a thermal coprecipitation method, using the core nanocrystals as seed crystals, and preparing three-layer core-shell structure nanocrystals by an induced layer-by-layer epitaxial growth method; performing surface protonation treatment on the three-layer core-shell structure nanocrystals prepared in step 1; dispersing the dual-mode orthogonal multicolor luminescent three-layer core-shell structure nanocrystals prepared in step 2 in an aqueous solution containing a surfactant and an additive, and ultrasonically dispersing them uniformly to obtain the dual-mode orthogonal multicolor fluorescent security and anti-counterfeiting ink. The dual-mode orthogonal multicolor fluorescent security and anti-counterfeiting ink prepared by this method has orthogonal luminescence characteristics in response to excitation wavelengths, and can achieve multicolor luminescence output under different excitation conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical anti-counterfeiting, and in particular relates to a dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink and a preparation method thereof. Background Art

[0002] Optical anti-counterfeiting has been widely used in the field of security and anti-counterfeiting due to its advantages such as good stability, high concealment, low cost and easy operation.

[0003] In recent years, many new luminescent materials have been used as security inks in fields such as information protection and security anti-counterfeiting. In particular, nanomaterials with orthogonal up-conversion luminescence have attracted great attention and interest from researchers due to their unique characteristics of responding to orthogonal multi-color luminescence in response to multi-element near-infrared light excitation. In nanomaterials with orthogonal luminescence properties, multiple different luminescent regions can respond to different near-infrared light excitations, and the multiple luminescence processes do not interfere with each other. Ultimately, multi-color luminescence regulation with high color purity that is independent of excitation power can be achieved in the same nanomaterial. Although such materials with orthogonal luminescence properties have shown great application prospects in the fields of information coding, data encryption, security anti-counterfeiting, etc., the security anti-counterfeiting inks currently prepared based on these materials are all single-mode orthogonal up-conversion luminescence, which has the problem of too single a luminescence mode, resulting in a lack of effective protection of security information and the risk of being deciphered.

[0004] Therefore, the development of a new dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink that combines optical frequency up-conversion and down-conversion mechanisms is of great significance and value for promoting its application in the field of advanced anti-counterfeiting. Summary of the Invention

[0005] In response to the common problem of a single luminescence mode in security inks based on orthogonal up-conversion luminescence in the prior art, the present invention provides a dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink and a preparation method thereof. The dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink prepared by this method has orthogonal luminescence characteristics that respond to the excitation wavelength and can achieve multi-color luminescence output under different excitation conditions.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for preparing a dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink comprises the following steps:

[0008] Step 1: Preparation of three-layer core-shell nanocrystals with dual-mode orthogonal multicolor luminescence;

[0009] Core nanocrystals were prepared by thermal coprecipitation, and three-layer core-shell structure nanocrystals were prepared by inducing layer-by-layer epitaxial growth using the core nanocrystals as seeds.

[0010] Step 2: Preparation of water-soluble dual-mode orthogonal multicolor luminescent three-layer core-shell structure nanocrystals;

[0011] The three-layer core-shell structure nanocrystals prepared in step 1 are subjected to surface protonation treatment;

[0012] Step 3: Preparation of security and anti-counterfeiting ink;

[0013] The dual-mode orthogonal multicolor luminescent three-layer core-shell structure nanocrystals prepared in step 2 are dispersed in an aqueous solution containing a surfactant and an additive, and ultrasonically dispersed evenly to obtain a dual-mode orthogonal multicolor fluorescent security anti-counterfeiting ink.

[0014] Furthermore, the step 1 specifically includes the following contents:

[0015] NaGdF4:Yb / Tm core nanocrystals were prepared by thermal coprecipitation method, and then the core nanocrystals were used as seeds to induce the epitaxial growth of NaGdF4:Ce / Eu first shell to prepare NaGdF4:Yb / Tm@NaGdF4:Ce / Eu core-shell structure nanocrystals; then the prepared core-shell structure nanocrystals were used as seeds to induce the epitaxial growth of NaErF4 second shell to prepare NaGdF4:Yb / Tm@NaGdF4:Ce / Eu@NaErF4 double-layer core-shell structure nanocrystals; finally, the obtained double-layer core-shell structure nanocrystals were used as seeds to induce the epitaxial growth of NaYF4 third shell to prepare NaGdF4:Yb / Tm@NaGdF4:Ce / Eu@NaErF4@NaYF4 triple-layer core-shell structure nanocrystals.

[0016] Furthermore, the step 2 specifically includes the following contents:

[0017] The three-layer core-shell structure nanocrystals prepared in step 1 are subjected to surface protonation treatment using dilute hydrochloric acid with a pH of 4, so that the surface ligands fall off in the form of oleic acid molecules, thereby forming water-soluble dual-mode orthogonal multicolor luminescent three-layer core-shell structure nanocrystals without surface ligand modification.

[0018] Furthermore, the step three specifically includes the following contents:

[0019] The dual-mode orthogonal multicolor luminescent three-layer core-shell structure nanocrystals prepared in step 2 are dispersed in a 20% by mass aqueous solution of a surfactant polyvinyl pyrrolidone. After being fully mixed, a 5% by mass fraction of an additive sodium carboxymethyl cellulose is added according to a volume ratio of 1:1-1:2, and ultrasonic dispersion is performed to obtain a security anti-counterfeiting ink with dual-mode orthogonal multicolor fluorescence.

[0020] Furthermore, the surfactant described in step three is polyvinyl pyrrolidone, polymethyl methacrylate, polyethylene glycol distearoyl phosphatidylethanolamine, polyacrylic acid or polyvinyl chloride, etc.; the surfactant can be used to prevent the agglomeration of water-soluble dual-mode orthogonal multicolor luminescent three-layer core-shell structure nanocrystals.

[0021] Furthermore, the additive in step three is sodium carboxymethyl cellulose, sodium lauryl sulfate, glycerol, triolein or toluene-methyl benzoate; the additive can play a role in adjusting the viscosity of the security anti-counterfeiting ink.

[0022] On the other hand, the present invention also provides a dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink, which is prepared by the above method.

[0023] Furthermore, the dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink is composed of water-soluble dual-mode orthogonal multi-color luminescent NaGdF4:Yb / Tm@NaGdF4:Ce / Eu@NaErF4@NaYF4 three-layer core-shell structure nanocrystals, surfactants, additives and deionized water; calculated by mass percentage, the nanocrystals are 0.01-0.5%, the fluorescent material is 0.001-2%, the surfactant is 1-5%, the additive is 5-20%, and the rest is water.

[0024] Compared with the prior art, the advantages of the present invention are as follows:

[0025] (1) The dual-mode orthogonal multicolor fluorescent security anti-counterfeiting ink prepared by the method of the present invention utilizes a dual-mode luminescence mechanism that combines optical frequency up-conversion and down-conversion. This overcomes the disadvantage of conventional single-mode fluorescent anti-counterfeiting technology, which is easily replaced by other anti-counterfeiting technologies with similar luminescence modes due to its single mode.

[0026] (2) The upconversion luminescence process involved in the dual-mode orthogonal multicolor fluorescent security anti-counterfeiting ink prepared by this method is based on excitation by two different wavelengths of near-infrared light (980nm and 808nm). This avoids the problem of traditional upconversion fluorescent ink being easily counterfeited due to the single excitation wavelength.

[0027] (3) The dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink prepared by this method has orthogonal luminescence characteristics that respond to excitation wavelengths and can achieve multi-color luminescence output under different excitation conditions. The specific process is as follows: under 980nm near-infrared light excitation, the ink can produce blue up-conversion luminescence; under 808nm near-infrared light excitation, the ink can produce green up-conversion luminescence; under 254nm ultraviolet light excitation, the ink can produce red down-conversion luminescence. Moreover, the three luminescence processes based on the dual mode are independent of each other and do not interfere with each other. This solves the problem that most current fluorescent anti-counterfeiting inks have poor anti-counterfeiting effects due to the single luminescence color. This anti-counterfeiting technology based on triple excitation response dual-mode orthogonal three-primary color luminescence greatly improves the security level of anti-counterfeiting and increases the difficulty of counterfeiting. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly describes the drawings required for the specific embodiments or the description of the prior art. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. Elements or parts in the drawings are not necessarily drawn to scale.

[0029] Figure 1 : Photo of the dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink prepared by this method;

[0030] Figure 2 : Luminescent photo of the dual-mode orthogonal multicolor fluorescent security anti-counterfeiting ink prepared by this method under 980nm near-infrared light excitation;

[0031] Figure 3 : Luminescent photograph of the dual-mode orthogonal multicolor fluorescent security anti-counterfeiting ink prepared by this method under 808nm near-infrared light excitation;

[0032] Figure 4 : Luminescent photograph of the dual-mode orthogonal multicolor fluorescent security anti-counterfeiting ink prepared by this method under 254nm ultraviolet light excitation;

[0033] Figure 5 : Emission spectrum of the dual-mode orthogonal multicolor fluorescent security anti-counterfeiting ink prepared by this method under 980nm near-infrared light excitation;

[0034] Figure 6 : Emission spectrum of the dual-mode orthogonal multicolor fluorescent security anti-counterfeiting ink prepared by this method under 808nm near-infrared light excitation;

[0035] Figure 7 : Emission spectrum of the dual-mode orthogonal multicolor fluorescent security anti-counterfeiting ink prepared by this method under 254nm ultraviolet light excitation. DETAILED DESCRIPTION

[0036] In order to clearly and completely describe the technical solution and specific working process of the present invention, the specific implementation methods of the present invention are as follows in conjunction with the accompanying drawings:

[0037] Example 1

[0038] This embodiment provides a method for preparing a dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink, which specifically includes the following steps:

[0039] Step 1: Preparation of three-layer core-shell nanocrystals with dual-mode orthogonal multicolor luminescence;

[0040] Core nanocrystals were prepared by thermal coprecipitation, and three-layer core-shell structure nanocrystals were prepared by inducing layer-by-layer epitaxial growth using the core nanocrystals as seeds.

[0041] Step 2: Preparation of water-soluble dual-mode orthogonal multicolor luminescent three-layer core-shell structure nanocrystals;

[0042] The three-layer core-shell structure nanocrystals prepared in step 1 are subjected to surface protonation treatment;

[0043] Step 3: Preparation of security and anti-counterfeiting ink;

[0044] The dual-mode orthogonal multicolor luminescent three-layer core-shell structure nanocrystals prepared in step 2 are dispersed in an aqueous solution containing a surfactant and an additive, and ultrasonically dispersed evenly to obtain a dual-mode orthogonal multicolor fluorescent security anti-counterfeiting ink.

[0045] Example 2

[0046] The preparation of three-layer core-shell structured nanocrystals with dual-mode orthogonal multicolor luminescence specifically includes the following steps:

[0047] (1) Preparation of NaGdF4:Yb / Tm (40 / 1 mol%) core nanocrystals;

[0048] A 0.4 mmol solution of rare earth acetate (Gd(CH3COO)3 (59%), Yb(CH3COO)3 (40%), and Tm(CH3COO)3 (1%)) in a predetermined ratio, along with 3 mL of oleic acid and 7 mL of octadecene, was added to a 50 mL two-necked round-bottom flask. The mixture was stirred and heated to 150°C for 60 minutes to form the oleic acid complex Gd / Yb / Tm-OA precursor. After the precursor solution cooled naturally to room temperature, 4 mL of NH4F (0.4 mol / L) as a fluorine source and 2 mL of NaOH (0.5 mol / L) in methanol were added sequentially. The mixture was then heated to 50°C and stirred continuously for 30 minutes. After thorough stirring, the mixture was heated to 100°C and reacted under vacuum for 10 minutes to remove methanol, water, and low-boiling-point substances from the system. Finally, the mixture was heated to 290°C under argon protection and reacted for 90 minutes. After the reaction was completed, the mixture was naturally cooled to room temperature, the precipitated product was separated by centrifugation, and washed repeatedly with cyclohexane and ethanol three times. Finally, the obtained product was dispersed in cyclohexane for characterization and induction of shell growth.

[0049] (2) Preparation of NaGdF4:Yb / Tm@NaGdF4:Ce / Eu (12 / 5mol%) core-shell structured nanocrystals;

[0050] A 0.4 mmol aqueous solution of rare earth acetate (Gd(CH3COO)3 (83%), Ce(CH3COO)3 (12%), and Eu(CH3COO)3 (5%)) was added to a 50 mL two-necked round-bottom flask along with 3 mL of oleic acid and 7 mL of octadecene. The mixture was stirred and heated to 150°C for 60 minutes to form the oleic acid complex Gd / Ce / Eu-OA precursor. After the precursor solution cooled naturally to room temperature, the prepared core nanocrystals (~0.4 mmol) were added, followed by a fluorine source (4 mL of NH4F (0.4 mol / L)) and a sodium source (2 mL of NaOH (0.5 mol / L) in methanol). The mixture was then heated to 50°C and stirred continuously for 30 minutes. After thorough stirring, the mixture was heated to 100°C and reacted under vacuum for 10 minutes to remove methanol, water, and low-boiling-point substances from the system. Finally, the mixture was heated to 290°C under argon protection and reacted for 90 minutes. After the reaction was completed, the mixture was naturally cooled to room temperature, and the precipitated product was separated by centrifugation and washed three times with cyclohexane and ethanol. Finally, the obtained product was dispersed in cyclohexane for characterization and further induction of shell growth.

[0051] (3) Preparation of NaGdF4:Yb / Tm@NaGdF4:Ce / Eu@NaErF4 double-layer core-shell structured nanocrystals;

[0052] A 0.4 mmol aqueous solution of rare earth acetate (Er(CH3COO)3), 3 mL of oleic acid, and 7 mL of octadecene were added to a 50 mL two-necked round-bottom flask and heated to 150°C for 60 minutes with stirring to form the oleic acid complex Er-OA precursor. After the precursor solution cooled naturally to room temperature, the prepared core-shell nanocrystals (~0.4 mmol) were added, followed by 4 mL of NH4F (0.4 mol / L), a fluorine source, and 2 mL of NaOH (0.5 mol / L) in methanol. The mixture was then heated to 50°C and stirred continuously for 30 minutes. After thorough stirring, the mixture was heated to 100°C and reacted under vacuum for 10 minutes to remove methanol, water, and low-boiling substances. Finally, the mixture was heated to 290°C under argon protection for 90 minutes. After the reaction was completed, the mixture was cooled naturally to room temperature, and the precipitated product was separated by centrifugation and washed three times with cyclohexane and ethanol. The resulting product was dispersed in cyclohexane for characterization and further shell growth induction.

[0053] (4) Preparation of NaGdF4:Yb / Tm@NaGdF4:Ce / Eu@NaErF4@NaYF4 three-layer core-shell structure nanocrystals;

[0054] A 0.4 mmol aqueous solution of rare earth acetate Y(CH3COO)3, 3 mL of oleic acid, and 7 mL of octadecene were added to a 50 mL two-necked round-bottom flask and heated to 150°C for 60 minutes to form the oleic acid complex Y-OA precursor. After the precursor solution cooled naturally to room temperature, the prepared double-layer core-shell nanocrystals (~0.4 mmol) were added, followed by 4 mL of NH4F (0.4 mol / L), a fluorine source, and 2 mL of NaOH (0.5 mol / L) in methanol. The temperature was then raised to 50°C and stirred continuously for 30 minutes. After thorough stirring, the mixture was heated to 100°C and reacted under vacuum for 10 minutes to remove methanol, water, and low-boiling substances. Finally, the temperature was raised to 290°C under argon protection for 90 minutes. After the reaction was completed, the mixture was cooled naturally to room temperature, and the precipitated product was separated by centrifugation and washed three times with cyclohexane and ethanol. The resulting product was dispersed in cyclohexane for characterization.

[0055] Example 3

[0056] The preparation of water-soluble dual-mode orthogonal multicolor luminescent three-layer core-shell structure nanocrystals specifically includes the following steps:

[0057] The oleic acid ligands on the surface of the nanocrystals were protonated using dilute hydrochloric acid at pH 4. The specific process was as follows: 0.4 mmol of the oleic acid ligand-modified dual-mode orthogonal multicolor luminescent three-layer core-shell structure nanocrystals prepared in Example 2 were dispersed in 4 mL of anhydrous ethanol. After uniform dispersion, 4 mL of hydrochloric acid solution (pH 4) was added and ultrasonicated for 10 minutes. The mixture was then centrifuged at 16,000 rpm for 20 minutes. Finally, the collected product was repeatedly washed three times with anhydrous ethanol and dilute hydrochloric acid to obtain water-soluble dual-mode orthogonal multicolor luminescent three-layer core-shell structure nanocrystals.

[0058] Example 4

[0059] The preparation of dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink specifically includes the following steps:

[0060] The water-soluble dual-mode orthogonal multicolor luminescent three-layer core-shell structure nanocrystals prepared in Example 3 were dispersed in a 20% by mass aqueous solution of a surfactant polyvinyl pyrrolidone. The resulting dispersion was ultrasonically vibrated for 30 minutes, and then a 5% by mass fraction of an additive, sodium carboxymethyl cellulose, was added in a volume ratio of 1:1 to 1:2. After ultrasonic dispersion was uniform, a security anti-counterfeiting ink with dual-mode orthogonal multicolor fluorescence was obtained.

[0061] The dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink prepared in this embodiment has the characteristics of triple excitation response dual-mode orthogonal three-primary color luminescence. The specific luminescence process is as follows:

[0062] (1) Under 980nm near-infrared light excitation, the ink can produce blue upconversion luminescence;

[0063] (2) Under the excitation of 808nm near-infrared light, the ink can produce green upconversion luminescence;

[0064] (3) Under 254nm ultraviolet light excitation, the ink can produce red down-conversion luminescence.

[0065] like Figure 1 As shown, the dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink prepared by the method of the present invention is colorless and transparent and has good dispersibility.

[0066] like Figure 2 As shown, under the excitation of 980nm near-infrared light, the dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink prepared by the method of the present invention emits blue light under the excitation of 980nm near-infrared light.

[0067] like Figure 3 As shown, under the excitation of 808nm near-infrared light, the dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink prepared by the method of the present invention emits green light under the excitation of 808nm near-infrared light.

[0068] like Figure 4 As shown, under the excitation of 254nm ultraviolet light, the dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink prepared by the method of the present invention emits red light under the excitation of 254nm ultraviolet light.

[0069] like Figure 5 As shown, the dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink prepared by the method of the present invention emits blue light under 980nm near-infrared light excitation.

[0070] like Figure 6 As shown, the dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink prepared by the method of the present invention emits green light under 808nm near-infrared light excitation.

[0071] like Figure 7 As shown, the dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink prepared by the method of the present invention emits red light under the excitation of 254nm ultraviolet light.

[0072] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0073] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0074] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing a dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink, characterized in that: The specific steps include: Step 1: Preparation of core-shell nanocrystals with dual-mode orthogonal multicolor luminescence; The core nanocrystals are prepared by thermal coprecipitation method, and the core nanocrystals are used as seeds to prepare core-shell structure nanocrystals by inducing layer-by-layer epitaxial growth. Step 2: Preparation of water-soluble dual-mode orthogonal multicolor luminescent core-shell structured nanocrystals; The core-shell structure nanocrystals prepared in step 1 are subjected to surface protonation treatment; Step 3: Preparation of security and anti-counterfeiting ink; The dual-mode orthogonal multi-color luminescent core-shell structure nanocrystals prepared in step 2 are dispersed in an aqueous solution containing a surfactant and an additive, and ultrasonically dispersed uniformly to obtain a dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink; The step 1 specifically includes the following contents: NaGdF4:Yb / Tm core nanocrystals were prepared by thermal coprecipitation method, and then the core nanocrystals were used as seeds to induce the epitaxial growth of NaGdF4:Ce / Eu first shell to prepare NaGdF4:Yb / Tm@NaGdF4:Ce / Eu core-shell structure nanocrystals; then the prepared core-shell structure nanocrystals were used as seeds to induce the epitaxial growth of NaErF4 second shell to prepare NaGdF4:Yb / Tm@NaGdF4:Ce / Eu@NaErF4 double-layer core-shell structure nanocrystals; finally, the obtained double-layer core-shell structure nanocrystals were used as seeds to induce the epitaxial growth of NaYF4 third shell to prepare NaGdF4:Yb / Tm@NaGdF4:Ce / Eu@NaErF4@NaYF4 core-shell structure nanocrystals.

2. The method for preparing a dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink according to claim 1, characterized in that: The step 2 specifically includes the following contents: The core-shell structured nanocrystals prepared in step 1 are subjected to surface protonation treatment using dilute hydrochloric acid at a pH of 4, so that the surface ligands fall off in the form of oleic acid molecules, thereby forming water-soluble dual-mode orthogonal multicolor luminescent core-shell structured nanocrystals without surface ligand modification.

3. The method for preparing a dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink according to claim 1, characterized in that: The step three specifically includes the following contents: The dual-mode orthogonal multicolor luminescent core-shell structure nanocrystals prepared in step 2 are dispersed in a 20% by mass aqueous solution of a surfactant polyvinyl pyrrolidone. After being fully mixed, a 5% by mass fraction of an additive sodium carboxymethyl cellulose is added according to a volume ratio of 1:1-1:2, and ultrasonic dispersion is performed to obtain a security anti-counterfeiting ink with dual-mode orthogonal multicolor fluorescence.

4. The method for preparing a dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink according to claim 1, characterized in that: The surfactant described in step three is polyvinyl pyrrolidone, polymethyl methacrylate, polyethylene glycol distearoyl phosphatidylethanolamine, polyacrylic acid or polyvinyl chloride; the surfactant is used to prevent the agglomeration of water-soluble dual-mode orthogonal multicolor luminescent core-shell structure nanocrystals.

5. The method for preparing a dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink according to claim 1, characterized in that: The additive in step three is sodium carboxymethyl cellulose, sodium lauryl sulfate, glycerol, triolein or toluene-methyl benzoate.

6. The method for preparing a dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink according to claim 1, characterized in that: The dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink is composed of water-soluble dual-mode orthogonal multi-color luminescent NaGdF4:Yb / Tm@NaGdF4:Ce / Eu@NaErF4@NaYF4 core-shell structure nanocrystals, surfactants, additives and deionized water; calculated by mass percentage, the nanocrystals are 0.01-0.5%, the fluorescent material is 0.001-2%, the surfactant is 1-5%, the additive is 5-20%, and the rest is water.

7. A dual-mode orthogonal multi-color fluorescent security anti-counterfeiting ink, characterized in that: The method is prepared by any one of claims 1 to 6.

Images