A high color difference color-changing material, color-changing ink, and preparation method and application thereof

Abstract

The present invention discloses a high color difference color changing material, color changing ink and its preparation method and application, which relates to the field of rare earth luminescent materials. The first object is to provide a high color difference color changing material, the high color difference color changing material is Er 3+ and Tm 3+ As the dopant ion co-doped Gd2(MoO4)3 crystal, Er 3+ The doping concentration is 20 mol%, Tm 3+ The doping concentration is 9 mol%. The present invention discloses a high-color-difference color-changing material, a color-changing ink, and a preparation method and application thereof. The high-color-difference color-changing material features adjustable luminescent color. The preparation method offers advantages such as simple operation, low cost, and superior color-changing performance to existing technologies. The color-changing ink features continuously adjustable luminescent color under 1550nm laser excitation, making it suitable for power-responsive dynamic fluorescent anti-counterfeiting applications.

Description

Technical Field

[0001] The present invention relates to the field of rare earth luminescent materials, and in particular to a high color difference color changing material, color changing ink, and a preparation method and application thereof. Background Art

[0002] For years, counterfeiting, substandard products, and pirated goods have persisted despite repeated crackdowns, significantly impacting the normal operation and sales of genuine products, even threatening the survival of some authentic brands. Anti-counterfeiting technology is crucial to the survival and development of businesses and products, playing a vital role in ensuring the normal operation of authentic products and protecting their intellectual property rights. Anti-counterfeiting inks are widely used in many anti-counterfeiting printing fields. These include fluorescent inks, photochromic inks, and temperature-sensitive inks. Traditional anti-counterfeiting inks rely on static fluorescent technology, which is susceptible to imitation.

[0003] Upconversion luminescence emits various high-energy visible photons by absorbing low-energy near-infrared photons. Since the responses of different emissions to external environments (such as temperature and pressure) are characteristic, it is particularly suitable for the development of advanced dynamic fluorescent anti-counterfeiting. However, the temperature and pressure response technologies or time-resolved technologies that have been widely reported have high requirements for application conditions, which is not conducive to the application and promotion of daily anti-counterfeiting. In comparison, power-responsive upconversion luminescence color adjustment can not only achieve the effect of dynamic anti-counterfeiting but also has a simpler method of use and lower production cost. Unfortunately, the current upconversion luminescence that responds highly sensitively to excitation power mostly uses more than two luminescence centers, and is subject to the quenching effect of cross-relaxation on luminescence, and its upconversion luminescence efficiency does not exceed 0.5%. Therefore, it is crucial to design and develop multi-color upconversion luminescence that responds highly sensitively to excitation power based on a single luminescence center.

[0004] Among the many up-conversion luminescence ions, Er 3+ Because it has typical green and red light emission in the visible band, it is particularly suitable for regulating the luminous chromaticity that the human eye responds to with high sensitivity, such as the orange-yellow color on the CIE-1931 chromaticity diagram. 3+ With a long-lived intermediate energy level, it acts as an activator to help obtain higher upconversion efficiency. 3+ In the activated system, since the green and red light emission energy levels have similar population channels, it is difficult to obtain multicolor upconversion luminescence with high sensitivity to the excitation power.

[0005] Existing open literature (“Improved Response of Upconversion Luminescence Color to Pump Power through the Coupling of Er 3+ and Tm 3+"Tao Pang, et al., J. Phys. Chem. C, 2022, 126: 1481-1488. January 2022.) The study found that with the help of Er 3+ -Tm 3+ Coupling can improve Er 3+ The red and green light emission intensity ratio responds to the 980nm laser power, but this study still has the problem of low power responsiveness, resulting in insignificant color changes and difficulty in meeting practical applications. Summary of the Invention

[0006] Regarding the existing technology 3+ The bottleneck problem of the response of luminescent color to 980nm excitation power is solved. The first purpose of the present invention is to provide a high color difference color-changing material, which has the characteristic of adjustable luminescent color.

[0007] The second object of the present invention is to provide a method for preparing a color-changing ink, which has the advantages of simple operation, low cost of use and better color-changing effect than the existing technology.

[0008] The third object of the present invention is to provide a color-changing ink, which has the characteristic of continuously adjustable luminescent color over a wide range under 1550nm laser excitation.

[0009] A fourth object of the present invention is to provide a use of a color-changing ink suitable for use as power-responsive dynamic fluorescent anti-counterfeiting.

[0010] To achieve the first purpose above, the present invention provides the following technical solutions: a high color difference color changing material, the high color difference color changing material is Er 3+ and Tm 3+ As the dopant ion co-doped Gd2(MoO4)3 crystal, Er 3+ The doping concentration is 20 mol%, Tm 3+ The doping concentration is 9 mol%, where the doping concentration is the percentage of the doping ions in the total molar content of rare earth cations in the high color difference color-changing material.

[0011] By adopting the above technical solution, due to Er 3+ The doping concentration is moderate and Tm 3+ The doping concentration is higher, when increasing Er 3+ While reducing the distance between ions, 3+ and Tm 3+ The ionic distance between them, therefore, we obtain Er 3+ Energy transfer upconversion is suppressed and Er 3+ -Tm 3+ The energy transfer between them is improved.

[0012] Furthermore, the high color difference color changing material is monoclinic phase Gd2(MoO4)3:Er 3+ ,Tm 3+ .

[0013] Furthermore, the high color difference color-changing material is prepared by the following method:

[0014] A gadolinium source compound, an erbium source compound, a thulium source compound, and a molybdenum source compound were weighed and mixed in a molar ratio of (71 mol% Gd + 20 mol% Er + 9 mol% Tm):Mo = 2:3, and the mixture was mechanically ground for 20 minutes. The mixture was calcined in an air atmosphere to obtain the target product at a calcination temperature of 700°C and a calcination time of 6 hours.

[0015] Furthermore, the high color difference color-changing material can realize the luminescence changing from red to orange-yellow and then to yellow-green under the excitation of 1550nm laser.

[0016] To achieve the above-mentioned second purpose, the present invention provides the following technical solution: a method for preparing a color-changing ink, uniformly dispersing a high color difference color-changing material into the ink to obtain a color-changing ink; the weight ratio of the high color difference color-changing material to the ink is 1:1.

[0017] To achieve the third purpose mentioned above, the present invention provides the following technical solution: a color-changing ink, which is prepared by the preparation method described above.

[0018] To achieve the fourth purpose mentioned above, the present invention provides the following technical solution: the application of the color-changing ink in the field of anti-counterfeiting, and further, the color-changing ink is used as a power-responsive color-changing anti-counterfeiting material.

[0019] Furthermore, the method comprises: printing the color-changing ink on a substrate to form a desired pattern, and drying the printing ink naturally; the substrate is paper, glass, plastic or metal;

[0020] Furthermore, the printing method is selected from one of screen printing, inkjet printing or manual printing methods.

[0021] In summary, the present invention has the following beneficial effects:

[0022] First, the high color difference color-changing material of the present invention is composed of 20 mol% Er 3+ and 9 mol% Tm 3+ The frequency up-conversion luminescent material formed by co-doping monoclinic Gd2(MoO4)3 can obtain continuously adjustable luminescent colors from red to yellow to green under the condition of 1550nm excitation.

[0023] Second, by using 1550nm laser excitation, Er is significantly improved 3+The response of the red and green light emission intensity ratio to the laser power is better than that of Er2Mo4O 15 :4%Tm 3+ The responsiveness is nearly 4 times higher under 980nm excitation, making it more difficult to imitate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0025] Figure 1 The XRD spectrum of the high color difference color-changing material disclosed in the embodiment of the present invention;

[0026] Figure 2 This is a graph showing the relationship between the red and green light emission intensity ratio and the laser power of the high color difference color-changing material disclosed in an embodiment of the present invention under 1550nm laser excitation;

[0027] Figure 3 The CIE chromaticity diagram of the high color difference color-changing material disclosed in the embodiment of the present invention;

[0028] Figure 4 The emission spectra of the high color difference color-changing material disclosed in the embodiment of the present invention under 1550nm and 980nm excitation;

[0029] Figure 5 XRD spectrum of the material disclosed in Comparative Example 1 of the present invention;

[0030] Figure 6 The material disclosed in Comparative Example 1 of the present invention was excited at 1550nm (power density 32.31W / cm 2 ) spectrum and the integrated intensities of green and red emissions;

[0031] Figure 7 Gd2(MoO4)3:20%Er disclosed in Comparative Example 2 of the present invention 3+ ,9%Tm 3+ The XRD spectrum of the product was obtained by calcining at 700 °C for 2 h;

[0032] Figure 8 Gd2(MoO4)3:20%Er disclosed in Comparative Example 2 of the present invention 3+ ,9%Tm 3+ The relationship curves between the red and green light emission intensity ratio and the 1550nm laser power density were obtained by calcining at 700℃ for 2, 4, 6, 8, and 10h.

[0033] Figure 9 XRD spectrum of the material disclosed in Comparative Example 3 of the present invention;

[0034] Figure 10 The material disclosed in Comparative Example 3 of the present invention is subjected to a power density of 3.50 W / cm 2 and 28.90W / cm 2 Spectrum and red-green light emission intensity ratio under 1550nm laser radiation. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following will be combined with the appended drawings of the embodiments of the present invention. Figure 1-10 The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0036] Example

[0037] The high color difference color-changing material is prepared by the following method:

[0038] Gd2O3, Er2O3, Tm2O3 and MoO3 were weighed and mixed in a molar ratio of (71% Gd + 20% Er + 9% Tm):Mo = 2:3, and then mechanically ground for 20 minutes. Then, the mixture was calcined in an air atmosphere at a temperature of 700°C and a calcination time of 6 hours to obtain the target product (97-023-1703).

[0039] Figure 1 The XRD spectrum of the high color difference color changing material of this embodiment is shown. According to the diffraction spectrum, the high color difference color changing material is a monoclinic phase Gd2(MoO4)3:Er 3+ ,Tm 3+ (97-023-1703).

[0040] Figure 2 The relationship between the red and green light emission intensity ratio and laser power of the high color difference color-changing material in the embodiment of the present application under laser excitation is shown in FIG. 1 . The power density of the 1550nm laser is changed from 1.33W / cm 2 Increased to 68.39W / cm 2 , the red-green light emission intensity ratio decreased from 121.21 to 2.47.

[0041] Figure 3 The CIE chromaticity diagram of the high color difference color-changing material prepared in the embodiment of the present application is as follows: Figure 3 It can be seen that when the power density is 1.33W / cm 2 , 28.90W / cm2 、39.99W / cm 2 、68.39W / cm 2 The corresponding coordinates of the high color difference color-changing materials are (0.69, 0.28), (0.59, 0.40), (0.45, 0.55), and (0.38, 0.62). Figure 3 By connecting the equal-energy white point (0.33, 0.33) and the above-mentioned color points on the CIE chromaticity diagram and extending them to intersect with the spectral color trajectory, it can be seen that the main wavelengths of the spectrum of the prepared high color difference color-changing material are ~660nm, ~595nm, ~571nm, and ~560nm, respectively, corresponding to a blue shift of nearly 100nm in the main wavelength of the spectrum.

[0042] Figure 4 The emission spectrum of the high color difference color-changing material in the embodiment of the present application under 1550nm and 980nm excitation. Figure 4 It can be seen that the high color difference color-changing material in the embodiment of the present application has a significantly stronger red-green light emission intensity ratio under 1550nm excitation than under 980nm excitation. Therefore, the high color difference color-changing material in the embodiment of the present application can be used for 1550nm excitation to achieve continuous color adjustment from red to yellow-green.

[0043] Combine Figure 2 and Figure 4 It can be seen that because the main wavelength is 1.33W / cm 2 The peak wavelength of the red light emission band is close to that at a power density of , indicating that the high color difference color-changing material in the embodiment of the present application has almost reached the maximum theoretical value of the red-green light emission intensity ratio regulation.

[0044] Comparative Example

[0045] Comparative Example 1: The only difference from the embodiment is that the calcination temperature is 900° C. and the calcination time is 10 h.

[0046] Figure 5 The XRD spectrum of the comparative example material is shown in Figure 1. According to the diffraction spectrum, the comparative example 1 material is orthorhombic phase Gd2(MoO4)3:Er 3+ ,Tm 3+ (97-000-9486).

[0047] Figure 6 The spectrum of the comparative material under 1550nm excitation and the integrated intensity of green and red light emission. 2 , and its red-green light emission intensity ratio is as high as 67.8, indicating that its power response color adjustment ability is far lower than the high color difference color-changing material disclosed in the embodiment.

[0048] Comparative Example 2: The only difference from the embodiment is that the calcination time is 2 hours.

[0049] Figure 7 The XRD spectrum of the comparative example material is shown in Figure 2. According to the diffraction spectrum, the comparative example 2 material is a monoclinic phase Gd2(MoO4)3:Er 3+ ,Tm 3+ (97-023-1703).

[0050] Figure 8 Gd2(MoO4)3:20%Er at different calcination times at 700℃ 3+ ,9%Tm 3+ The red and green light emission intensity ratio changes with power density under 1550nm excitation. Compared with the best 6h calcined sample, the color-changing material provided in Comparative Example 2 has a power response color-changing ability far lower than the high color difference color-changing material disclosed in the examples of this application.

[0051] Comparative Example 3: The only difference from the embodiment is that Tm 3+ The doping concentration was 0 mol%, and the calcination time was 10 h.

[0052] Figure 9 The XRD spectrum of the comparative example material is shown in Figure 3. According to the diffraction spectrum, the comparative example 3 material is a monoclinic phase Gd2(MoO4)3:Er 3+ ,Tm 3+ (97-023-1703).

[0053] Figure 10 The comparative material has a power density of 3.50W / cm 2 and 28.90W / cm 2 The spectrum and red and green emission intensity ratio of 1550nm laser irradiation. 3+ Comparing the color-tuning capabilities of the doped materials under the same excitation conditions reveals that the power responsiveness of the luminous intensity and chromaticity of the comparative material is far lower than that of the high-color-difference color-changing materials disclosed in the examples of this application. Furthermore, the dominant wavelength of the material in Comparative Example 3 of this application falls in the yellow-green region, where the human eye has poor resolution, further limiting its color-tuning capabilities.

[0054] Application Examples

[0055] The preparation method of the color-changing ink involved in this application is: the high color difference color-changing material prepared in the above-mentioned high color difference color-changing material embodiment is uniformly dispersed into the ink to obtain the color-changing ink; the weight ratio of the high color difference color-changing material to the ink is 1:1.

[0056] The anti-counterfeiting application involved in this application is: color-changing ink is printed on a substrate to form a desired pattern, and then dried naturally; the substrate is paper, glass, plastic or metal.

[0057] In summary, it can be seen that the creativity of the present invention lies in the high color difference color-changing material provided, which, through the optimization of material components and processes, realizes the main wavelength adjustment of ~100nm under 1550nm excitation, significantly improving the application effect of power-responsive luminescent color-changing anti-counterfeiting.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high color difference color-changing material, characterized in that: The high color difference color changing material is Er 3+ and Tm 3+ Gd2(MoO4)3:Er as co-doping ions 3+ ,Tm 3+ Crystal, of which Er 3+ The doping concentration is 20%, Tm 3+ The doping concentration is 9%, where the doping concentration is the percentage of doping ions in the total molar content of rare earth cations in the high color difference color-changing material, and the high color difference color-changing material is a monoclinic phase.

2. The high color difference color changing material according to claim 1, characterized in that: The high color difference color-changing material is prepared by the following method: A gadolinium source compound, an erbium source compound, a thulium source compound, and a molybdenum source compound were weighed according to a molar ratio of (71 mol% Gd + 20 mol% Er + 9 mol% Tm):Mo = 2:3, mixed, and ground. The mixture was calcined in an air atmosphere to obtain the target product at a calcination temperature of 700°C and a calcination time of 6 h.

3. The high color difference color changing material according to claim 1, characterized in that: The high color difference color-changing material realizes luminescence changing from red to orange-yellow and then to yellow-green under the excitation of 1550nm laser.

4. A method for preparing a color-changing ink, characterized in that: The high color difference color-changing material according to any one of claims 1 to 3 is uniformly dispersed in ink to obtain a color-changing ink; the weight ratio of the high color difference color-changing material to the ink is 1:

1.

5. A color-changing ink, characterized in that: The preparation method according to claim 4 is used to prepare the product.

6. Use of the color-changing ink as claimed in claim 5 in the field of anti-counterfeiting.

7. Use of the color-changing ink according to claim 6 in the field of anti-counterfeiting, characterized in that: include: Print the color-changing ink on the substrate to form the desired pattern and let it dry naturally; The printing substrate is paper, glass, plastic or metal.

8. The use of the color-changing ink in the anti-counterfeiting field according to claim 7, characterized in that: The printing method is selected from one of screen printing, inkjet printing or manual printing.

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