A stress-luminescent composite material, its preparation method and application

Abstract

This invention proposes a stress-luminescent composite material, its preparation method, and its application. The preparation method involves a dehydration condensation reaction between aminated stress-luminescent powder and carboxylated nanoparticles to obtain the stress-luminescent composite material. This invention modifies the stress-luminescent powder with nanoparticles via amide bonds, forming a stress-luminescent composite material with a micro / nano structure, exhibiting better stress-luminescence effect and good stress-luminescence stability. The introduction of high-hardness nanoparticles improves the stress transfer efficiency of the stress-luminescent material, thereby significantly enhancing the luminescence intensity of the stress-luminescent composite material. Since the luminescence intensity of the basic stress-luminescent composite material differs from that of the stress-luminescent powder, it can be applied in the field of anti-counterfeiting and encryption.

Description

Technical Field

[0001] This invention relates to the field of stress-luminescent materials technology, and in particular to a stress-luminescent composite material, its preparation method, and its application. Background Technology

[0002] Stress-luminescent materials have attracted great interest due to their unique luminescent properties, and have potential applications in stress sensors, stress distribution imaging, structural health diagnosis, novel light sources and displays, and optical anti-counterfeiting. However, strong and reproducible non-destructive stress-luminescent materials are still scarce, which greatly affects their practical application.

[0003] Document CN106590634 A discloses a micro / nano composite structure of doped zinc sulfide and its applications. 100 nm silica nanospheres and 2 μm doped zinc sulfide microparticles are dispersed in ethanol, stirred at 60 °C for 48-72 h, and dried. The silica nanospheres are uniformly adsorbed onto the doped zinc sulfide microparticles, resulting in a micro / nano composite structure. This micro / nano composite structure has the following problems: the nanoparticles are prone to detachment, resulting in poor stability; the luminescence intensity of the doped zinc sulfide in the micro / nano composite structure needs further improvement.

[0004] Most of the existing reports on anti-counterfeiting of stress-luminescent materials utilize the multi-mode luminescence properties (photoluminescence, phosphorescence, thermoluminescence, etc.) of stress-luminescent materials, with stress luminescence only serving as a demonstration of the possibility of anti-counterfeiting encryption. Summary of the Invention

[0005] This invention proposes a stress-luminescent composite material, its preparation method, and its application. By modifying nanoparticles onto stress-luminescent powder through amide bonds, a stress-luminescent composite material with a micro-nano structure is formed, which has better stress-luminescence effect and good stress-luminescence stability.

[0006] The technical solution of this invention is achieved as follows: a method for preparing a stress-luminescent composite material, comprising the following steps:

[0007] (1) Amination treatment of micron-sized stress luminescent powder;

[0008] (2) Carboxylating the nanoparticles;

[0009] (3) The amino-modified stress luminescent powder and carboxylated nanoparticles are subjected to a dehydration condensation reaction to obtain a stress luminescent composite material.

[0010] Furthermore, in step (1), the specific method for the amination treatment of the stress-induced luminescent powder is as follows:

[0011] Disperse 1-5g of stress luminescent powder in 20mL of ethanol solvent, then add 70-220μL of 3-aminopropyltriethoxysilane (APTES), stir for 2min, then add 210-660μL of deionized water, stir for more than two hours, wash three times with deionized water, and dry to obtain amination-modified stress luminescent powder.

[0012] Further, 1g of stress luminescent powder was dispersed in 20mL of ethanol, and then 70μL of APTES and 210μL of deionized water were added with stirring.

[0013] Furthermore, in step (3), the specific method for the dehydration condensation reaction is as follows:

[0014] 0.001-0.005 g of carboxylated nanoparticles were dispersed in 30 mL of morpholine ethanesulfonic acid buffer (MES), and then 0.01 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and 0.02 g of N-hydroxythiosuccinimide sodium salt (NHS) were added. The mixture was stirred for 20 min, centrifuged, and the precipitate was collected. The precipitate was then dispersed in 20 mL of deionized water (pH=7), and 1-5 g of aminated stress luminescent powder was added. The mixture was stirred for 12 h to obtain a stress luminescent composite material with a micro-nano structure.

[0015] Furthermore, the amount of carboxylated nanoparticles used is 0.0025g.

[0016] Furthermore, the nanoparticles are nanomaterials with a Mohs hardness greater than that of stress-luminescent powder and capable of surface carboxylation modification; under the premise of the same particle size, the greater the hardness, the better the luminescence performance of the stress-luminescent composite material. 100nm nanodiamonds (NDs) show better results than 100nm alumina nanoparticles, which in turn show better results than 100nm calcium carbonate nanoparticles. The nanoparticles can be spherical, plate-like, ellipsoidal, conical, or have various irregular morphologies.

[0017] Furthermore, the concentration of the morpholine ethanesulfonic acid buffer was 0.1M (M is an abbreviation for mol / L), and the pH was 6.0.

[0018] Furthermore, the diameter of the nanoparticles is 50-1000 nm, and the diameter of the stress luminescent powder is 10-50 μm.

[0019] Furthermore, the stress luminescence intensity of the obtained stress luminescent composite material is the strongest when the diameter ratio of the stress luminescent powder to the nanoparticles is 240 and the mass ratio is 400.

[0020] Furthermore, the nanoparticles are one or more of diamond, alumina, silicon dioxide, calcium carbonate, zinc oxide, and zirconium oxide.

[0021] Furthermore, the stress luminescent powder is any one or more of ZnS:Cu, ZnS:Mn, SrAl2O4:Eu,Dy, CaZnOS:Mn, CaZnOS:Tb, CaZnOS:Pr, CaZnOS:Sm, CaZnOS:Ho, CaZnOS:Dy, CaZnOS:Er, CaZnOS:Eu, CaZnOS-ZnS:Bi, CaZnOS-ZnS:Ag, CaZnOS-ZnS:Cu, CaZnOS-ZnS:Mn, CaZnOS-ZnS:Tb, CaZnOS-ZnS:Pr, CaZnOS-ZnS:Sm, CaZnOS-ZnS:Ho, CaZnOS-ZnS:Dy, CaZnOS-ZnS:Er, and CaZnOS-ZnS:Eu.

[0022] A stress-luminescent composite material, prepared by the aforementioned preparation method.

[0023] Application of a stress-luminescent composite material in anti-counterfeiting encryption labels.

[0024] The method for preparing the anti-counterfeiting encryption label is as follows:

[0025] The stress-luminescent composite material and the elastic polymer precursor liquid are mixed and then screen-printed or printed to create an information encryption layer.

[0026] Stress-emitting powder and elastic polymer precursor liquid are mixed and then spin-coated onto the information encryption layer as an encapsulation layer;

[0027] Finally, drying and curing yields the anti-counterfeiting encrypted label. This label does not display encrypted information under natural light or ultraviolet light excitation; it only reveals encrypted information under tension due to the difference in luminous intensity between the information layer and the luminescent layer. This truly utilizes the characteristics of stress luminescence for its anti-counterfeiting and encryption applications.

[0028] Furthermore, the elastic polymer is PDMS.

[0029] The beneficial effects of this invention are:

[0030] This invention modifies nanoparticles on the surface of stress-luminescent powder with amide bonds to form a stress-luminescent composite material with a micro-nano structure, which has better stress-luminescence effect and good stress-luminescence stability. The introduction of high-hardness nanoparticles improves the stress transmission efficiency of the stress-luminescent material, making the luminescence intensity of the stress-luminescent composite material much stronger than that of the stress-luminescent powder.

[0031] This invention prepares an encrypted information layer by screen printing or printing the stress-luminescent composite material elastic polymer mixture slurry, and spin-coates the stress-luminescent powder elastic polymer mixture slurry into an encapsulation layer to form an anti-counterfeiting encrypted label; based on the difference in stress luminescence intensity between unmodified nanoparticle stress-luminescent materials and modified nanoparticle stress-luminescent composite materials, and the similarity in photoluminescence intensity, an anti-counterfeiting encrypted label that can be read only under stress is prepared. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the stress-luminescent composite material of the present invention and an anti-counterfeiting label under tension.

[0034] Figure 2 The stress luminescence curves of the stress-luminescent composite materials in Examples 1, 5, and 6 are shown.

[0035] Figure 3 The stress luminescence curves of the stress-luminescent composite materials in Examples 1, 3, and 4 are shown.

[0036] Figure 4 The preparation process of the anti-counterfeiting label of this invention;

[0037] Figure 5 The image shows the stress luminescence stability test result of the stress-luminescent composite material prepared in Example 1.

[0038] Figure 6 The stress luminescence curves of the stress-luminescent composite materials prepared in Example 1 and Comparative Example 1;

[0039] Figure 7 This is a photograph showing the "ZZU" information being read under stretching conditions. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Example 1

[0042] A method for preparing a stress-luminescent composite material includes the following steps:

[0043] (1) Amination treatment of stress luminescent powder

[0044] 1 g of stress-emitting phosphor ZnS:Cu was dispersed in 20 mL of ethanol and stirred for 10-30 min. Then, 70 μL of APTES was added and stirred for 2 min. Next, 210 μm of deionized water was added and stirred for 2 h to allow the APTES to be fully hydrolyzed. The supernatant was removed by centrifugation, and the precipitate was washed three times with deionized water. Then, it was dried in a forced-air drying oven to obtain the amination-modified stress-emitting phosphor. The diameter of the stress-emitting phosphor was 24 μm.

[0045] (2) Carboxylation treatment of nanoparticles

[0046] 0.5 g of nanodiamonds (NDs) were placed in a muffle furnace and kept at 450 °C for 5 h. After cooling, they were immersed in 90 mL of a strong acid solution (H₂SO₄:HNO₃ = 3:1, vol / vol) and stirred with a magnetic stirrer at 80 °C for 24 h. The precipitate was then collected by centrifugation. The precipitate was placed in 100 mL of NaOH aqueous solution (0.1 M) and stirred at 100 °C for 1 h. After centrifugation, the precipitate was collected again. The precipitate was then placed in 100 mL of HCl aqueous solution (0.1 M) and stirred at 100 °C for 1 h. Finally, the precipitate was washed three times with deionized water and dried in a forced-air drying oven to obtain carboxylated NDs. The diameter of the NDs was 100 nm, and the Mohs hardness of the nanodiamonds was greater than 3.5.

[0047] (3) Dehydration condensation reaction of aminated stress luminescent powder and carboxylated nanoparticles.

[0048] 0.0025 g of carboxylated NDs was dispersed in 30 mL of MES buffer (0.1 M, pH = 6.0), 0.01 g of EDC and 0.02 g of NHS were added, and the mixture was stirred for 20 min. After centrifugation, the precipitate was collected and dispersed in 20 mL of deionized water (pH = 7). 1 g of aminated stress-luminescent powder was added, and the mixture was stirred for 12 h to obtain the stress-luminescent composite material (ZnS:Cu / NDs).

[0049] Figure 1 This is a schematic diagram of the stress-luminescent composite material prepared in this embodiment. It can be seen that NDs are modified on the ZnS:Cu surface.

[0050] Example 2

[0051] like Figure 4 As shown, the method for preparing anti-counterfeiting labels includes the following steps:

[0052] (1) The prepolymer of PDMS and the curing agent are mixed and stirred evenly at a mass ratio of 9:1 to form a PDMS precursor liquid. The bubbles are removed by standing or by using a vacuum pump. The standing time is 4 hours and the vacuum pump extraction time is 30 minutes.

[0053] (2) Add stress luminescent powder ZnS:Cu to the PDMS precursor solution and stir evenly to obtain a mixed slurry of ZnS:Cu and PDMS. Remove bubbles by standing or by using a vacuum pump. The standing time is 4 hours and the vacuum pump extraction time is 30 minutes.

[0054] (3) Add stress-luminescent composite material ZnS:Cu / NDs to the PDMS precursor solution and stir until homogeneous to obtain a mixed slurry of ZnS:Cu / NDs and PDMS. Remove air bubbles by standing or using a vacuum pump. The standing time is 4 hours, and the vacuum pump extraction time is 30 minutes.

[0055] (4) The mixed paste of ZnS:Cu / NDs and PDMS in step (3) is printed on the acrylic plate in the form of “ZZU” using the screen printing method to form an encrypted information layer. Then, the mixed paste of ZnS:Cu and PDMS is dropped onto the acrylic plate and a coating layer is formed by spin coating with a homogenizer at a speed of 500 rad / min.

[0056] (5) Then put the acrylic sheet into a drying oven for drying at 80°C for 2 hours; after drying, peel off the film formed on the acrylic sheet to obtain the anti-counterfeiting label.

[0057] Under tension, the "ZZU" information is read, such as Figure 7 As shown.

[0058] Example 3

[0059] This embodiment is basically the same as that of embodiment 1, except that the mass of carboxylated NDs in step (3) is 0.0015g.

[0060] Example 4

[0061] This embodiment is basically the same as that of embodiment 1, except that the mass of carboxylated NDs in step (3) is 0.004g.

[0062] Example 5

[0063] This embodiment is basically the same as embodiment 1, except that the size of NDs in step (2) is 300nm.

[0064] Example 6

[0065] This embodiment is basically the same as embodiment 1, except that the size of NDs in step (2) is 1000nm.

[0066] Figure 2 The figures show the stress luminescence curves of the stress-luminescent composite materials prepared in Examples 1, 5, and 6. It can be seen that the luminescence intensity of the stress-luminescent composite material with introduced NDs is stronger than that of the stress-luminescent powder without modified NDs. Moreover, it can be seen that the luminescence intensity enhancement factor increases as the size of NDs decreases.

[0067] Figure 3 The stress emission curves of the stress-luminescent composite materials prepared in Examples 1, 3 and 4 show that the optimal concentration of carboxylated NDs is 0.25%.

[0068] Figure 5 The image shows the stress luminescence stability test result of the stress-luminescent composite material prepared in Example 1. The luminescence intensity of the composite material remained stable after 8000 stress cycles, indicating that the composite material has high stability.

[0069] Comparative Example 1

[0070] 0.0025g of NDs was uniformly dispersed in 20mL of ethanol solvent and sonicated for half an hour. Then, 1g of stress luminescent powder was added to the beaker and stirred on a magnetic stirrer at a speed of 500rad / min until the solvent was completely evaporated to obtain mechanically mixed stress luminescent material with a diameter of 100nm.

[0071] Figure 6 The stress luminescence curves of the stress luminescent composite materials prepared in Example 1 and Comparative Example 1 are shown. By performing stress luminescence tests on the stress luminescent composite materials obtained by mechanically mixing ZnS:Cu with 100nm NDs and by linking them through amide bonds, it was found that the stress luminescent composite material linked by chemical bonds has a better stress luminescence effect than the stress luminescent composite material of mechanical mixing.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a stress-luminescent composite material, characterized in that, Includes the following steps: (1) Amination treatment of micron-sized stress luminescent powder; (2) Carboxylating the nanoparticles; (3) The aminated stress luminescent powder and carboxylated nanoparticles are subjected to a dehydration condensation reaction to obtain a stress luminescent composite material; The Mohs hardness of nanoparticles is greater than that of stress-luminescent powder; The nanoparticles are one or more of the following: diamond, alumina, silicon dioxide, calcium carbonate, zinc oxide, and zirconium oxide.

2. The method for preparing a stress-luminescent composite material according to claim 1, characterized in that, In step (1), the specific method for the amination treatment of the stress luminescent powder is as follows: Disperse 1-5g of stress luminescent powder in 20 mL of ethanol solvent, add 70-220 μL of 3-aminopropyltriethoxysilane, stir, then add 210-660 μL of deionized water, stir for more than two hours, wash with deionized water, and dry to obtain amination-modified stress luminescent powder.

3. The method for preparing a stress-luminescent composite material according to claim 1, characterized in that, In step (3), the specific method for the dehydration condensation reaction is as follows: 0.001-0.005 g of carboxylated nanoparticles were dispersed in 30 mL of morpholine ethanesulfonic acid buffer, and then 0.01 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.02 g of N-hydroxythiosuccinimide sodium salt were added and stirred. After centrifugation, the precipitate was dispersed in deionized water, and then 1-5 g of aminated stress luminescent powder was added and stirred for 12 h to obtain a stress luminescent composite material with micro-nano structure.

4. The method for preparing a stress-luminescent composite material according to claim 1, characterized in that, The diameter of the nanoparticles is 50-1000 nm, and the diameter of the stress luminescent powder is 10-50 μm.

5. The method for preparing a stress-luminescent composite material according to claim 1, characterized in that, The stress luminescent powders are ZnS:Cu, ZnS:Mn, SrAl2O4:Eu,Dy, CaZnOS:Mn, CaZnOS:Tb, CaZnOS:Pr, CaZnOS:Sm, CaZnOS:Ho, CaZnOS:Dy, CaZnOS:Er, CaZnOS:Eu, CaZnOS-ZnS:Bi, CaZnOS-ZnS : Any one or more of Ag, CaZnOS-ZnS:Cu, CaZnOS-ZnS:Mn, CaZnOS-ZnS:Tb, CaZnOS-ZnS:Pr, CaZnOS-ZnS:Sm, CaZnOS-ZnS:Ho, CaZnOS-ZnS:Dy, CaZnOS-ZnS:Er and CaZnOS-ZnS:Eu.

6. A stress-luminescent composite material, prepared by the preparation method according to any one of claims 1-5.

7. The application of the stress-luminescent composite material of claim 6 in an anti-counterfeiting encryption label.

8. The application according to claim 7, characterized in that: The preparation method of the anti-counterfeiting encryption label is as follows: Stress-luminescent composite material and elastic polymer precursor liquid are mixed and then used to make an information encryption layer; Stress-emitting powder and elastic polymer precursor liquid are mixed and then coated onto the information encryption layer as an encapsulation layer. Finally, the label is dried and cured to obtain an anti-counterfeiting encrypted label.

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