Colorful fluorescent anti-counterfeiting glass and preparation method thereof

Abstract

The invention discloses colored fluorescent anti-counterfeiting glass and a preparation method thereof, and relates to the technical field of fluorescent anti-counterfeiting. The method is based on porous glass and comprises the following steps that (1) the porous glass is immersed in a luminous solution to obtain luminous ion doped porous glass, and the luminous solution contains one or more luminous ions and is co-doped or non-co-doped with tin ions; and (2) carrying out micro-area heating on the anti-counterfeiting area of the luminous ion doped porous glass by using carbon dioxide laser to obtain an anti-counterfeiting pattern. According to the invention, carbon dioxide laser is adopted to carry out local micro-area heating scanning on the porous glass, luminous ions in a doped area are activated at a relatively low temperature, high-resolution fluorescent patterns (such as letters and marks) are formed, densification caused by high temperature is avoided, and the treated glass is still kept in a porous state.

Description

Technical Field

[0001] The present invention relates to the technical field of fluorescent anti-counterfeiting technology, and particularly relates to a colored fluorescent anti-counterfeiting glass and a preparation method thereof. Background Art

[0002] Due to its unique optical response characteristics, the fluorescent anti-counterfeiting technology has important applications in high-end packaging, currency anti-counterfeiting and other fields. Although traditional fluorescent anti-counterfeiting means (such as fluorescent inks, labels) are low in cost, they have defects such as being easy to copy, poor weather resistance, and low pattern resolution, and it is difficult to meet the high-security requirements. In recent years, fluorescent glass based on inorganic luminescent materials has gradually become a research hotspot, and its excellent chemical stability, high temperature resistance and long life characteristics provide a new direction for the fluorescent anti-counterfeiting technology.

[0003] At present, the preparation methods of fluorescent glass include sol-gel method and porous glass doping method. The sol-gel method uniformly disperses luminescent ions in the glass matrix through the sol-gel process, but high-temperature sintering (>800 °C) is prone to cause the closure of nanopores and ion agglomeration, and the luminescence efficiency is limited (for example, the patent application with the publication number of CN107082571A). In addition, the uniform distribution of active ions between the matrix and the crystal intensifies the non-radiative energy transfer (such as quenching effect), and it is difficult to achieve high-brightness luminescence. The porous glass doping method, relying on its high specific surface area and interconnected nanopore structure, can efficiently adsorb active ions (such as Eu³⁺, Tb³⁺, etc.), and form luminescent nanocrystals (such as SnO 2 ) through heat treatment. For example, the patent application with the publication number of CN111847886A discloses a preparation method of nano-crystalline glass containing tin dioxide. Through porous glass solution doping, primary heat treatment (400 - 900 °C), acid treatment and secondary heat treatment (900 - 1300 °C), the luminescent ions outside the crystal are selectively removed, so that the active ions are enriched in the SnO 2 nano-crystals inside, significantly improving the luminescence intensity and transparency of the glass. However, this method requires high-temperature densification treatment, resulting in the collapse of the porous structure and the inability to retain the dynamic regulation ability of the porous matrix, which limits its application in patterned anti-counterfeiting. The current technologies mostly focus on the optimization of overall performance. For example, the patent application with the publication number of CN102320746A improves white light emission by adjusting the ion distribution, but still does not solve the problem of local control of multi-color fluorescent patterns. Summary of the Invention

[0004] The present invention provides a preparation method of a colored fluorescent anti-counterfeiting glass. By locally scanning a porous glass based on laser micro-region activation, the luminescent ions in the doped region are activated, so as to form a high-resolution fluorescent pattern, in order to solve many problems existing in the preparation process of the existing colored fluorescent anti-counterfeiting glass, such as complex preparation process, poor luminescence efficiency, and difficult local control.

[0005] The technical solution adopted by the present invention is as follows: One of the objectives of the present invention is to provide a preparation method of a color fluorescent anti-counterfeiting glass, which is based on porous glass and includes the following steps: (1) Immerse the porous glass in a luminescent solution to obtain a porous glass doped with luminescent ions, where the luminescent solution contains single or multiple luminescent ions, with or without co-doping of tin ions; (2) Use a carbon dioxide laser to perform micro-area heating on the anti-counterfeiting area of the porous glass doped with luminescent ions to obtain an anti-counterfeiting pattern. The power of the carbon dioxide laser is 0.3 - 20 W, the spot diameter is 0.1 - 3 mm, and the power density ranges from 1 - 49 W / mm 2 , and the power density is the ratio of the carbon dioxide laser power to the spot area; the scanning speed is 20 - 250 mm / s, the number of scanning times is 20 - 800 times, and finally the cumulative temperature of micro-area heating is 300 - 700 °C.

[0006] In the present invention, the porous glass can be obtained commercially, or can be prepared according to the methods recorded in the literature or by self-made methods, where the methods recorded in the literature include any of the following methods recorded in the literature: (1) D. Chen, H. Miyoshi, T. Akai, T. Yazawa, Colorless transparent fluorescence material: sintered porous glass containing rare-earth and transition-metal ions, Appl. Phys. Lett. 86 (2005), 231908 - 231908. (2) Q. Zhang, Y. B. Qiao, B. Qian, G. P. Dong, J. Ruan, X. F. Liu, Q. L. Zhou, Q. X. Chen, J. R. Qiu, D. P. Chen, Luminescence properties of the Eu-doped porous glass and spontaneous reduction of Eu 3+ to Eu 2+ , J. Lumines.129(11), (2009) 1393 - 1397. (3)Y. Shen, S. Zheng, Q. Sheng, S. Liu, W. Li, D. Chen, Synthesis of nano - colloidal silica particles and their effects on the luminescence properties of Eu 2+ -doped High silica glass, Mater. Lett. 139, (2015) 373 - 376. The self - making steps of the porous glass are as follows: SiO 2 , B 2 O 3 , Al 2 O 3 , Na 2 CO 3 and CaO powder raw materials are mixed according to the weight percentages of (49 - 52):(28 - 30):1.6:(12 - 14):5.4, fired at high temperature, the glass melt is poured out and pressed thin, then put into a muffle furnace for heat treatment for phase separation, and then soaked in hot acid to obtain the porous glass; more preferably, the self - making steps of the porous glass are as follows: SiO 2 , B 2 O 3 , Al 2 O 3 , Na 2 CO 3 and CaO powder raw materials are mixed according to the weight percentages of 51:29:1.6:13:5.4, fired at 1400 °C for 2 hours, the glass melt is poured out and pressed thin, put into a 600 °C muffle furnace for heat treatment for 24 hours for phase separation, and then soaked in 100 °C 1 mol / L hot hydrochloric acid for 24 hours to obtain the porous glass.

[0007] Furthermore, the porous glass is porous silica glass, and the pore size of the porous glass is 4 - 1000 nm.

[0008] Even further, the pore size of the porous glass is 4 - 50 nm.

[0009] Even further, the porous glass is porous high - silica glass with uniformly distributed nano - micropores inside.

[0010] Furthermore, the immersion time of the porous glass in the luminescent solution is 20 minutes - 24 hours.

[0011] Even further, the immersion time of the porous glass in the luminescent solution is 30 minutes.

[0012] Further, the concentration of the tin ions is 0.1 - 2 mol / L, and the concentration of the luminescent ions is 0.05 - 1 mol / L.

[0013] Still further, the concentration of the tin ions is 0.8 mol / L, and the concentration of the luminescent ions is 0.4 mol / L.

[0014] Further, the luminescent ions are one or more of europium (Eu) ions, chromium (Cr) ions, manganese (Mn) ions, erbium (Er) ions, nickel (Ni) ions, cerium (Ce) ions, terbium (Tb) ions, ytterbium (Yb) ions, neodymium (Nd) ions, thulium (Tm) ions, praseodymium (Pr) ions, samarium (Sm) ions, and copper (Cu) ions.

[0015] The second object of the present invention is to provide a color fluorescent anti-counterfeiting glass prepared by the above preparation method.

[0016] In summary, compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The present invention uses a carbon dioxide laser to locally micro-regionally heat and scan the porous glass, activates the luminescent ions in the doped region at a relatively low temperature to form a high-resolution fluorescent pattern (such as letters and logos), and avoids densification caused by high temperature. After treatment, the glass still remains in a porous state.

[0017] 2. Through the co-doping and selective activation of different luminescent ions (such as SnO 2 :Eu³⁺ red light, Tb³⁺ green light, Eu²⁺ blue light), the present invention can achieve multi-color anti-counterfeiting on a single matrix. For example, through the co-doping of Sn ions and Eu³⁺, under the scanning of a carbon dioxide laser, the Sn ions form SnO 2 lattice and Eu³⁺ enters SnO 2 lattice and still remains Eu³⁺, thereby realizing red fluorescence; green fluorescence is realized by doping Tb; in the case of no Sn doping, Eu³⁺ directly contacts the porous glass (i.e., SiO 2 component) under the scanning of a carbon dioxide laser and is easily formed into Eu 2+ ions, thereby realizing blue fluorescence; in addition, Tb can be doped as a whole first to achieve an overall green background, and then local blue and red fluorescent patterns can be formed.

[0018] 3. The present invention abandons the traditional high-temperature sintering and acid treatment steps and only requires one-step laser treatment, significantly reducing the energy consumption and time cost. Description of the Drawings

[0019] Figure 1 Monochromatic fluorescent patterns of blue, green, and red prepared in Examples 1 - 3.

[0020] Figure 2The green background + blue pattern, green background + red pattern, and three-color mixed letter fluorescent patterns prepared in Examples 4 to 6.

[0021] Figure 3 The laser-engraved pattern prepared in Comparative Example 1. Detailed implementation manners

[0022] The present invention will be specifically described below in conjunction with the detailed implementation manners and examples, and the advantages and various effects of the present invention will be presented more clearly therefrom. Those skilled in the art should understand that these detailed implementation manners and examples are used to illustrate the present invention, rather than limiting the present invention.

[0023] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as having the meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as the general understanding of those skilled in the art to which the present invention belongs. In case of contradiction, this specification shall prevail.

[0024] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchases or can be prepared by existing methods.

[0025] The present application will be described in detail below in conjunction with the examples and experimental data.

[0026] Example 1 This example provides a method for preparing a colored fluorescent glass, and the specific steps are as follows: (1) Doping of porous glass solution; Prepare a mixed aqueous solution of SnCl 4 and EuCl 3 , wherein the concentration of Sn 4+ is 0.8 mol / L and the concentration of Eu 3+ is 0.4 mol / L. Immerse the porous glass in the above mixed solution for 30 minutes; take it out and dry it at 10°C to 120°C (it can also be air-dried) for later use.

[0027] The preparation process of the porous glass in this example is as follows: Respectively, SiO 2 , B 2 O 3 , Al 2 O 3 , Na 2 CO 3Mix the raw materials of and CaO powder in a weight percentage of 51: 29: 1.6: 13: 5.4, fire at 1400 °C for 2 hours, pour out the molten glass and press it thin, put it into a muffle furnace at 600 °C for heat treatment for 24 hours for phase separation, and then soak it in hot hydrochloric acid at 100 °C and 1 mol / L for 24 hours to obtain porous glass; the pore size range of the porous glass is 4-50 nm.

[0028] (2)Carbon dioxide laser scanning heating; scan the letter E. The power is 2W, the spot diameter is 0.5mm, and the power density is about 10 W / mm 2 , the scanning speed is 100 mm / s, and the number of scans is 200 times. As Figure 1 shown in Figure c of, the scanned color fluorescent glass presents a red letter E under ultraviolet light excitation.

[0029] Example 2 The implementation method is the same as that of Example 1, except that in this example, the mixed solution of SnCl 4 and EuCl 3 is replaced with a single Tb ion solution. As Figure 1 shown in Figure b of, the scanned color fluorescent glass presents a green letter E under ultraviolet light excitation.

[0030] Example 3 The implementation method is the same as that of Example 1, except that in this example, the mixed solution of SnCl 4 and EuCl 3 is replaced with a single Eu 3+ ion solution. As Figure 1 shown in Figure a of, the formation of SnO 2 is missing. After scanning, Eu directly contacts SiO 2 , and it is easily converted into Eu 2+ , and the obtained color fluorescent glass presents a blue letter E under ultraviolet light excitation.

[0031] Example 4 This example provides a preparation method of color fluorescent glass, and the specific steps are as follows: (1)Prepare aqueous solutions of 0.4 mol / L TbCl 3 and EuCl 3 for standby; (2)Immerse the porous glass in the above Tb ion solution for 30 minutes; take it out and dry it at 10 °C - 120 °C; (3)Perform carbon dioxide laser overall scanning on the porous glass doped with Tb ions, with a power of 20W and a spot diameter of 3mm. At this time, the power density is about 2.8 W / mm 2 , the scanning speed is 100 mm / s, and the number of scans is 200 times; (4) Immerse the overall scanned porous glass into the above Eu 3+ ion solution for 30 minutes; take it out and dry it at 10°C - 120°C; (5) Perform carbon dioxide laser scanning on the porous glass doped with Eu ions for the second time, with a power of 2 W, a spot diameter of 0.5 mm, and a power density of about 10 W / mm 2 , a scanning speed of 100 mm / s, and 200 scanning times to obtain Pattern E.

[0032] As Figure 2 shown in Figure a in

[0033] Example 5 The implementation method is the same as that in Example 4, except that in this example, the Eu 3+ solution is replaced with a mixed solution of SnCl 4 and EuCl 3 . As Figure 2 shown in Figure b in

[0034] Example 6 This example provides a method for preparing colored fluorescent glass, and the specific steps are as follows: Divide the glass into 3 regions, and respectively dope Eu 3+ +Sn, Tb, Eu 3+ solutions in the 3 regions according to the above doping steps, and then scan the letters J, N, and U in the three regions with carbon dioxide laser respectively.

[0035] As Figure 2 shown in Figure c in

[0036] Comparative Example 1 The implementation method is the same as that in Example 1, except that in this example, the power of carbon dioxide laser scanning and heating is changed to 10 W, and the power density reaches about 51 W / mm 2 , and the glass appearance is etched with indented letters E. As Figure 3 , obvious indentations can be observed with the naked eye under natural light.

[0037] Comparative Example 2 The implementation method is the same as that in Example 1, except that in this example, the carbon dioxide laser spot diameter is changed to 0.2 mm, and the power density reaches about 63 W / mm 2 , and the glass appearance is etched with indentations.

[0038] It is not difficult to see from Comparative Example 1 and Comparative Example 2 that when using carbon dioxide laser scanning heating to form a fluorescence pattern or mark, with a power density (power / spot area) comparable to the prior art, it is easy to etch indentations on the glass, and a fluorescence pattern or mark can be obtained with a lower power density.

[0039] Finally, it should also be noted that the term "comprising", "including" or any other variant is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0040] The above-described embodiments only represent the specific implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the protection scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the technical solution of the present application, several variations and improvements can still be made, and these all fall within the protection scope of the present application.

Claims

1. A method for preparing colored fluorescent anti-counterfeiting glass, characterized in that: The method is based on porous glass and includes the following steps: (1) immersing porous glass in a luminescent solution to obtain luminescent ion-doped porous glass, wherein the luminescent solution contains a single or multiple luminescent ions, co-doped with or not co-doped with tin ions; (2) A carbon dioxide laser is used to micro-heat the anti-counterfeiting area of ​​the luminescent ion-doped porous glass to obtain an anti-counterfeiting pattern. The carbon dioxide laser power is 0.3~20W, the spot diameter is 0.1~3mm, and the power density ranges from 1~49 W / mm 2 , power density is the ratio of carbon dioxide laser power to spot area; scanning speed is 20~250 mm / s, scanning times are 20~800 times, and the final micro-area heating cumulative temperature is 300~700℃.

2. The method for preparing colored fluorescent anti-counterfeiting glass according to claim 1, characterized in that: The porous glass is porous silica glass, and the pore size of the porous glass is 4-1000nm.

3. The method for preparing colored fluorescent anti-counterfeiting glass according to claim 2, characterized in that: The pore diameter of the porous glass is 4-50 nm.

4. The method for preparing colored fluorescent anti-counterfeiting glass according to claim 2, characterized in that: The porous glass is porous high-silicon glass with nano-micropores evenly distributed inside.

5. The method for preparing colored fluorescent anti-counterfeiting glass according to claim 1, characterized in that: The porous glass is immersed in the luminescent solution for 20 minutes to 24 hours.

6. The method for preparing colored fluorescent anti-counterfeiting glass according to claim 5, characterized in that: The porous glass was immersed in the luminescent solution for 30 minutes.

7. The method for preparing colored fluorescent anti-counterfeiting glass according to claim 1, characterized in that: The concentration of the tin ions is 0.1-2 mol / L, and the concentration of the luminescent ions is 0.05-1 mol / L.

8. The method for preparing colored fluorescent anti-counterfeiting glass according to claim 6, characterized in that: The concentration of the tin ions is 0.8 mol / L, and the concentration of the luminescent ions is 0.4 mol / L.

9. The method for preparing colored fluorescent anti-counterfeiting glass according to claim 1, characterized in that: The luminescent ions are one or more of europium ions, chromium ions, manganese ions, erbium ions, nickel ions, cerium ions, terbium ions, ytterbium ions, neodymium ions, thulium ions, praseodymium ions, samarium ions, and copper ions.

10. Colored fluorescent anti-counterfeiting glass prepared by the method for preparing colored fluorescent anti-counterfeiting glass according to any one of claims 1 to 9.

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