Bright red pigment dye-derived carbon quantum dot material and preparation method and application thereof in anti-counterfeiting field

Abstract

The invention provides a scarlet pigment dye-derived carbon quantum dot and a preparation method and application thereof in the anti-counterfeiting field, and relates to the technical field of organic photochromic materials.The preparation method comprises the steps that scarlet pigment dye is dissolved in an organic solvent, then the scarlet pigment dye solution is subjected to a solvothermal reaction in a reaction kettle, and the scarlet pigment dye-derived carbon quantum dot is obtained; reacting to obtain a solution containing the carbon quantum dots; the bright red pigment dye is 6-(N-ethyl-4-toluidine)-2-methylfluorane, and the bright red pigment dye is 6-(N-ethyl-4-toluidine)-2-methylfluorane. According to the invention, the excitation and emission of the fluorescent substance are controlled by photostimulation, so that the fluorescent substance generates dynamic fluorescence color change, dynamic anti-counterfeiting is realized, and the anti-counterfeiting grade is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of organic photochromic materials, and in particular to a magenta dye-derived carbon quantum dot material, a preparation method thereof, and an application in the field of anti-counterfeiting. Background Art

[0002] In recent years, photoluminescent anti-counterfeiting materials have gradually become a hot topic. However, due to their static luminescence, the anti-counterfeiting level of traditional luminescent materials is relatively low. As a new type of fluorescent nanomaterial, carbon quantum dots (CQDs) have strong application potential in the field of photoluminescent camouflage due to their adjustable bandgap emission, high photo / thermal stability, good solution processability, and low toxicity. In the prior art, more attention is paid to static anti-counterfeiting and information encryption based on color changes, lacking the application of photochromic materials in dynamic anti-counterfeiting. By using light stimulation to control the excitation and emission of fluorescent substances, making them produce dynamic fluorescence color changes, dynamic anti-counterfeiting can be achieved and the anti-counterfeiting level can be improved.

[0003] In view of this, the present invention is specifically proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of a magenta dye-derived carbon quantum dot material and its application in the field of anti-counterfeiting. By using light stimulation to control the excitation and emission of fluorescent substances, making them produce dynamic fluorescence color changes, dynamic anti-counterfeiting can be achieved and the anti-counterfeiting level can be improved.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] In the first aspect of the present invention, a preparation method of a magenta dye-derived carbon quantum dot material is provided, including: dissolving the magenta dye in an organic solvent, and then carrying out a solvothermal reaction on the magenta dye solution in a reaction kettle, and obtaining a solution containing carbon quantum dots after the reaction; the magenta dye is 6-(N-ethyl-4-toluidino)-2-methylfluorane.

[0007] Further, the organic solvent is N,N-dimethylformamide.

[0008] Further, the temperature of the solvothermal reaction is 170 - 190 °C, and the treatment time is 3 - 5 hours.

[0009] Further, the addition ratio range of the magenta dye to the organic solvent is: adding 0.5 g to 1.5 g of the magenta dye to every 30 ml of the organic solvent.

[0010] Further, under ultraviolet light, the fluorescence color of the carbon quantum dots is green, blue-green or blue; under visible light or sunlight, the fluorescence color of the carbon quantum dots is yellow.

[0011] Furthermore, the size distribution of the carbon quantum dots is 3.68 ± 0.7 nm.

[0012] Furthermore, the maximum excitation wavelength of the carbon quantum dots is 365 nm, and the maximum emission wavelength is 450 nm.

[0013] In the second aspect of the present invention, there is provided a carbon quantum dot material derived from a scarlet pigment dye obtained by the preparation method of the first aspect.

[0014] In the third aspect of the present invention, there is provided an anti-counterfeiting application of the carbon quantum dot material derived from the scarlet pigment dye prepared by the preparation method of the first aspect or the carbon quantum dot material derived from the scarlet pigment dye described in the second aspect. A solution containing carbon quantum dots obtained by the preparation method of the first aspect is used to draw a pattern on a wet substrate, and then the color of the pattern is observed under visible light or sunlight and ultraviolet light respectively. The authenticity is judged by the colors shown under different illuminations.

[0015] Furthermore, the substrate is any one of paper products and textiles.

[0016] The preparation of a carbon quantum dot material derived from a scarlet pigment dye provided by the present invention and its application in the field of anti-counterfeiting have the following beneficial effects:

[0017] 1. The raw materials of the present invention are cheap and easily available, and a fluorescent carbon quantum dot solution is prepared by simple solvothermal carbonization. The preparation method is simple and efficient.

[0018] 2. The photochromic material of the present invention has a fast color change speed. The color and fluorescence color of the sample can be changed within 20 s, and the light response is sensitive.

[0019] 3. Different optical information can be obtained by optical excitation in different states of the present invention, and the anti-counterfeiting effect is better. Description of the Drawings

[0020] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 It is the transmission electron microscope image of the prepared material in Example 1 of the present invention;

[0022] Figure 2 It is the particle size distribution diagram of the prepared material in Example 1 of the present invention;

[0023] Figure 3Raman analysis diagram of the preparation material in Example 1 of the present invention;

[0024] Figure 4 Fourier transform infrared spectrum diagram of the preparation material in Example 1 of the present invention;

[0025] Figure 5 Ultraviolet-visible absorption spectrum diagram of the preparation material in Example 1 of the present invention;

[0026] Figure 6 Fluorescence lifetime spectrum diagram of the preparation material in Example 1 of the present invention;

[0027] Figure 7 Fluorescence excitation and emission spectrum diagrams of the preparation material in Example 1 of the present invention;

[0028] Figure 8 Pictures of the fluorescent carbon quantum dot material prepared in Example 1 of the present invention under sunlight and 365 nm ultraviolet light;

[0029] Figure 9 Pictures of the fluorescent carbon quantum dot material prepared in Example 2 of the present invention under sunlight and 365 nm ultraviolet light;

[0030] Figure 10 Pictures of the fluorescent carbon quantum dot material prepared in Example 3 of the present invention under sunlight and 365 nm ultraviolet light;

[0031] Figure 11 Application photo of single-layer anti-counterfeiting in Example 4 of the present invention, with the substrate being filter paper and the pattern being a bouquet;

[0032] Figure 12 Application photo of single-layer anti-counterfeiting in Example 4 of the present invention, with the substrate being cotton cloth and the pattern being a bouquet. Detailed implementation manners

[0033] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. The process parameters not specified in the following embodiments are usually in accordance with conventional conditions.

[0034] In the ranges disclosed in the present invention, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0035] According to the first aspect of the present invention, the present invention provides a method for preparing a carbon quantum dot material derived from a scarlet pigment dye, comprising: dissolving the scarlet pigment dye in an organic solvent, and then carrying out a solvothermal reaction on the scarlet pigment dye solution in a reaction kettle to obtain a solution containing carbon quantum dots after the reaction; the scarlet pigment dye is 6-(N-ethyl-4-toluidino)-2-methylfluorane.

[0036] The reaction kettle described in the present invention can be a reaction vessel lined with polytetrafluoroethylene, and the solvothermal reaction can be carried out in a heating container such as an oven that can be heated; the scarlet pigment dye is an organic small molecule compound.

[0037] As an alternative embodiment of the method for preparing the carbon quantum dot material derived from the scarlet pigment dye of the present invention, the organic solvent is N,N-dimethylformamide.

[0038] As an alternative embodiment of the method for preparing the carbon quantum dot material derived from the scarlet pigment dye of the present invention, the temperature of the solvothermal reaction is 170-190 °C (175 °C, 180 °C, 185 °C), and the treatment time is 3-5 hours (such as 3.5 hours, 4 hours, 4.5 hours).

[0039] If the treatment time of the solvothermal reaction in the present invention is less than 3 hours, the solvothermal reaction is not complete, the carbon quantum dots are not completely formed, and the yield is low; if it exceeds 5 hours, the carbon quantum dots are partially decomposed, the oxidation time is long, the fluorescence efficiency is low, and the time consumption is long.

[0040] As an alternative embodiment of the method for preparing the carbon quantum dot material derived from the scarlet pigment dye of the present invention, the addition ratio range of the scarlet pigment dye to the organic solvent is: adding 0.5 g to 1.5 g of the scarlet pigment dye to every 30 ml of the organic solvent. Typically and non-limitingly, it can be: adding 0.6 g of the scarlet pigment dye to every 30 ml of the organic solvent, adding 0.9 g of the scarlet pigment dye to every 30 ml of the organic solvent, adding 1.2 g of the scarlet pigment dye to every 30 ml of the organic solvent, adding 1.4 g of the scarlet pigment dye to every 30 ml of the organic solvent. The solution containing carbon quantum dots obtained at this ratio can show yellow or light yellow under visible light or sunlight, and can show green, blue-green or blue under ultraviolet light.

[0041] As an alternative embodiment of the preparation method of the carbon quantum dot material derived from the scarlet pigment dye of the present invention, under ultraviolet light, the fluorescence color of the carbon quantum dots is green, blue-green or blue; under visible light or sunlight, the fluorescence color of the carbon quantum dots is yellow.

[0042] As an alternative embodiment of the preparation method of the carbon quantum dot material derived from the scarlet pigment dye of the present invention, the size distribution of the carbon quantum dots is 3.68 ± 0.7 nm (such as 3 nm, 3.2 nm, 3.4 nm, 3.6 nm, 3.8 nm, 4.0 nm, 4.2 nm).

[0043] As an alternative embodiment of the preparation method of the carbon quantum dot material derived from the scarlet pigment dye of the present invention, the maximum excitation wavelength of the carbon quantum dots is 365 nm, and the maximum emission wavelength is 450 nm.

[0044] According to the second aspect of the present invention, the present invention provides a carbon quantum dot material derived from a scarlet pigment dye prepared by the preparation method of the first aspect above.

[0045] According to the third aspect of the present invention, the present invention provides an anti-counterfeiting application of a carbon quantum dot material derived from a scarlet pigment dye. A pattern is drawn on a moist substrate using a solution containing carbon quantum dots obtained by the preparation method of the first aspect or the carbon quantum dot material provided in the second aspect, and then the color of the pattern is observed under visible light or sunlight and ultraviolet light respectively. The authenticity is judged by the colors displayed under different illuminations.

[0046] As an alternative embodiment, the carbon quantum dot solution prepared by the present invention can be directly or after dilution inhaled into a blank marker pen as ink, and then different patterns are drawn on different moist substrates.

[0047] Since the dry solid powder has no fluorescence, only the solution state has fluorescence, and the drying process of the dry substrate will lose the solvent and generate powder, so the pattern can only be drawn on the moist substrate.

[0048] As an alternative embodiment of the anti-counterfeiting application of the carbon quantum dot material derived from the scarlet pigment dye of the present invention, the substrate is any one of paper products and textiles.

[0049] For the anti-counterfeiting application of the carbon quantum dot material derived from the scarlet pigment dye of the present invention, the pattern can be any pattern such as a bouquet of lilies, an eagle, a sunflower, etc.

[0050] The present invention will be further described in detail below with specific examples and comparative examples.

[0051] Example 1

[0052] A preparation method of a fluorescent carbon quantum dot material, comprising the following steps:

[0053] Step 1: Take 0.5 g of 6-(N-ethyl-4-toluidino)-2-methylfluorane and add it to 15 ml of N,N-dimethylformamide solvent, and stir evenly.

[0054] Step 2: Transfer the mixed solution obtained in Step 1 to a reaction kettle, and react at 180 °C for 4 h to obtain a solution containing carbon quantum dot nanomaterials, denoted as CDs.

[0055] Example 2

[0056] The difference between Example 2 and Example 1 is that the reaction time in Step 2 is changed to 3 h, denoted as CDs-1.

[0057] Example 3

[0058] The difference between Example 3 and Example 1 is that the reaction time in Step 2 is changed to 5 h, denoted as CDs-2.

[0059] Example 4

[0060] This example provides an anti-counterfeiting design method based on Example 1. Figures 11 - 12 It is an anti-counterfeiting pattern drawn on a substrate with the fluorescent carbon quantum dot solution prepared in Example 1; the fluorescent carbon quantum dot solution prepared in Example 1 is directly or diluted and then inhaled into a blank marker pen as ink, and then the material is drawn on the target substrate according to a certain pattern, and the substrate is any one of filter paper, cotton cloth, and paper towel. Figure 11 The substrate is filter paper. Figure 12 The substrate is cotton cloth. Figure 11 The ink used is obtained by diluting the carbon quantum dot solution prepared in Example 1 with the solvent N,N-dimethylformamide twice. Figure 12 The ink used is the carbon quantum dot solution prepared in Example 1. Figure 11 After the pattern is made, it presents an overall color under sunlight and no effective information can be seen. When the pattern is placed under ultraviolet excitation at 365 nm, it will present fluorescence emission, so as to read the information according to the fluorescence emission.

[0061] Effect data

[0062] Figure 1 It is a high-resolution TEM image of CDs. It can be seen that CDs show uniform particles, indicating that CDs have good dispersibility. Obvious lattice fringes of 0.22 nm can be observed in the inset, indicating the existence of a graphite structure with smaller lamellae.

[0063] Figure 2 It is the particle size distribution diagram of the nano quantum dots CDs. After calculation, the average size of CDs is 3.68 ± 0.7 nm.

[0064] The Raman spectrum of the carbon material shows two peaks between 1000 - 2000 cm-1, corresponding to the defect and graphitization peaks of the carbon material respectively. Figure 3 It can be seen that the CDs have a high degree of graphitization.

[0065] Figure 4 The infrared spectrum of CDs is shown, and the characteristic peak at 1642 cm -1 is attributed to the C=O stretching vibration band. The asymmetric and symmetric stretching of -COO- is located at 1388 cm -1 and the absorption peak at 1079 cm -1 belongs to the asymmetric stretching vibration of the C-O-C bond. The results show that the prepared CDs have a large number of oxygen-containing functional groups, which is beneficial to improving their water solubility.

[0066] The fluorescence properties of Example 1 are as Figures 5 - 7 shown. Figure 5 Figure is the UV-visible absorption spectrum of the CDs prepared in Example 1; Figure 6 Figure is the fluorescence lifetime spectrum of the CDs prepared in Example 1; Figure 7 Figure is the fluorescence excitation spectrum and emission spectrum of the CDs prepared in Example 1.

[0067] From Figure 5 it can be seen that Example 1 has three UV absorption peaks at 246 nm, 294 nm, and 330 nm, corresponding to the characteristic spectral bands of aromatic compounds and the n–π transition of the C=O bond. From Figure 6 it can be seen that the fluorescence lifetime of Example 1 is 1.03 ns. Figure 7 It can be seen that the optimal excitation wavelength and the maximum emission wavelength of Example 1 are 365 nm and 450 nm respectively.

[0068] For the fluorescent carbon quantum dots prepared in Example 1, the picture obtained within 20 s under UV lamp irradiation is as Figure 8 shown, and it can be seen that the liquid state of Example 1 emits blue-green fluorescence. As Figure 9 shown, the carbon quantum dot solution prepared in Example 2 is yellow under visible light and blue-green fluorescent under UV lamp. As Figure 10 shown, the carbon quantum dot solution prepared in Example 3 is yellow under visible light and blue fluorescent under UV lamp.

[0069] As Figures 11 - 12 shown, the prepared water-soluble fluorescent carbon quantum dot solution is drawn onto the substrate surface. Figure 11After the pattern is made, it presents an overall color under sunlight and no valid information can be seen. This is because the ink used to draw the pattern is obtained by diluting the carbon quantum dot solution prepared in Example 1 twice with the solvent N,N-dimethylformamide. The concentration of the carbon quantum dot solution is relatively small, and the fluorescence color is relatively light under a fluorescent lamp, so it cannot be seen with the naked eye. Figure 12 After the pattern is made, it presents a light yellow color under sunlight. The carbon quantum dot solution used is the carbon quantum dot solution prepared in Example 1 without dilution. When the printed substrate is detected with an excitation light source of 365 nm, a bright fluorescence effect can be seen on the substrate.

[0070] In summary, the present invention prepares a fluorescent carbon quantum dot material, which can show a fluorescence spectrum only under specific conditions through ultraviolet light irradiation, so as to achieve dynamic anti-counterfeiting, and has a relatively fast response speed.

[0071] 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 them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a carbon quantum dot material derived from a big red pigment dye, characterized in that, Including: Dissolve the magenta pigment dye in an organic solvent, and then carry out a solvothermal reaction on the magenta pigment dye solution in a reaction kettle. After the reaction, a solution containing carbon quantum dots is obtained; the magenta pigment dye is 6-(N-ethyl-4-toluidino)-2-methylfluorane.

2. The preparation method of the big red pigment dye-derived carbon quantum dot material according to claim 1, characterized in that, The organic solvent is N,N-dimethylformamide.

3. The preparation method of the carbon quantum dot material derived from the scarlet pigment dye according to claim 1, characterized in that, The temperature of the solvothermal reaction is 170-190 °C, and the treatment time is 3-5 hours.

4. The preparation method of the big red pigment dye-derived carbon quantum dot material according to claim 1, characterized in that, The addition ratio range of the magenta pigment dye to the organic solvent is: 0.5 g to 1.5 g of the magenta pigment dye is added to every 30 ml of the organic solvent.

5. The preparation method of the scarlet pigment dye-derived carbon quantum dot material according to any one of claims 1-4, characterized in that, Under ultraviolet light, the fluorescence color of the carbon quantum dots is green, blue-green or blue; under visible light or sunlight, the fluorescence color of the carbon quantum dots is yellow.

6. The preparation method of the scarlet pigment dye-derived carbon quantum dot material according to claims 1-4, characterized in that, The size distribution of the carbon quantum dots is 3.68±0.7 nm.

7. The preparation method of the big red pigment dye-derived carbon quantum dot material according to claims 1-4, characterized in that, The maximum excitation wavelength of the carbon quantum dots is 365 nm, and the maximum emission wavelength is 450 nm.

8. A carbon quantum dot material derived from a scarlet pigment dye, characterized in that, Obtained by the preparation method according to any one of claims 1-7.

9. Anti-counterfeiting application of a carbon quantum dot material derived from a bright red pigment dye, characterized in that, Use the solution containing carbon quantum dots obtained by the preparation method according to claims 1-7 to draw a pattern on a wet substrate, and then observe the color of the pattern under visible light or sunlight and ultraviolet light respectively, and judge the authenticity by the colors shown under different illuminations.

10. The anti-counterfeiting application of the carbon quantum dot material derived from the big red pigment dye according to claim 9, characterized in that, The substrate is any one of paper products and textiles.

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