Multi-color fluorescent anti-counterfeiting super-hydrophobic composite film and preparation method thereof

Abstract

The present application relates to the field of fluorescent anti-counterfeiting detection technology, in particular to a fluorescent anti-counterfeiting super-hydrophobic composite film with multiple color changes and a preparation method thereof.The fluorescent anti-counterfeiting super-hydrophobic composite film with multiple color changes can realize the color change of the film surface by changing the excitation wavelength.The multiple color changes are realized by blending two different fluorescent dyes, encapsulating the fluorescent dyes to prepare a fluorescent anti-counterfeiting emulsion, and then spraying the emulsion on the surface of a polymer substrate to obtain the fluorescent composite film with super-hydrophobic characteristics and multiple color changes.The fluorescent anti-counterfeiting composite film prepared by the present application has the characteristics of multiple color changes, strong fluorescent signal and good fluorescent performance stability.

Description

Technical Field

[0001] The present invention relates to the technical field of fluorescent anti-counterfeiting detection technology, and in particular to a fluorescent anti-counterfeiting super-hydrophobic composite film with multiple color changes and a preparation method thereof. Background Art

[0002] Counterfeiting and shoddy products are a global problem, posing a serious threat to people's health and economic wealth. The development of efficient and reliable anti-counterfeiting technologies can effectively identify product authenticity and prevent counterfeiting, which is of great significance to business development and protecting consumer rights. As a new anti-counterfeiting technology, fluorescent anti-counterfeiting, with its simplicity and reliability, has attracted close attention from scientists and entrepreneurs and is widely used in areas related to national economy and people's livelihoods, such as currency, food, and medicine. However, current fluorescent anti-counterfeiting technologies only have a single color, making them easily circumvented and imitated. Therefore, the development of a color-changing, multi-color fluorescent anti-counterfeiting technology has great fundamental research value and commercial application potential.

[0003] A two-component fluorescent composite material refers to the introduction of a second component into a first-component fluorescent material. Through this strategy, the luminescence performance is effectively improved. However, the second component in two-component fluorescent materials is currently considered to enhance the fluorescence intensity or broaden the luminescence range. Energy transfer occurs between the two components, and even if the excitation wavelength is changed, a single color of light is still emitted. On the other hand, whether it is a single-component fluorescent material or a two-component fluorescent material, its luminescence process is easily disturbed by the external environment, resulting in fluorescence quenching and a decrease in luminescence intensity. Organic fluorescent molecules have attracted much attention due to their adjustable structure and controllable luminescence range. However, organic luminescent materials have intramolecular rotation, which can cause a decrease in luminescence intensity. Summary of the Invention

[0004] To address the issues raised in the background art, the present invention first provides a two-component fluorescent material that can control the surface color of a film by varying the excitation wavelength. The two-component fluorescent material is then encapsulated to protect the fluorescent material's luminescence from external interference. Furthermore, the multi-color-changing fluorescent capsules are synergistically combined with a fluorinated surfactant and polydimethylsiloxane to produce a multi-color-changing anti-counterfeiting luminescent composite film with stable superhydrophobic properties, further enhancing the stability of the fluorescent anti-counterfeiting composite film.

[0005] The present invention provides a multi-color-changing anti-counterfeiting super-hydrophobic film using these two fluorescent materials as luminescent substances and a preparation method thereof, which is prepared according to the following steps:

[0006] (1) Preparation of fluorescent capsules

[0007] 1) Dissolve sodium dodecyl sulfate, sodium bicarbonate and polyvinylpyrrolidone in ultrapure water to obtain solution A; wherein the mass ratio of sodium dodecyl sulfate, sodium bicarbonate and polyvinylpyrrolidone is 1:0.1-0.8:0.6-2.6; preferably the mass ratio is 1:0.3:1.2.

[0008] 2) Add a mixture of 7-amino-4-methylcoumarin, indocyanine green and styrene to dichloromethane to obtain solution B. The mass ratio of 7-amino-4-methylcoumarin, indocyanine green and styrene is 1:0.02-0.2:30-200, and further preferably 1:0.1:90-110.

[0009] 3) Mix solution A and solution B, and after ultrasonic oscillation at low temperature (0°C) for 10-30 minutes, add potassium persulfate, and react at a temperature of 50-100°C for 5-30 hours. The reaction product is centrifuged and washed with distilled water and ethanol alternately for 3 times to obtain a multi-color-changing fluorescent capsule. Further, the mass ratio of sodium dodecyl sulfate, 7-amino-4-methylcoumarin and potassium persulfate is 30:10:5-50. Further preferably, the reaction is at 80°C for 12 hours.

[0010] (2) Preparation of a multi-color-changing fluorescent anti-counterfeiting super-hydrophobic composite film

[0011] 1) Add the multi-color-changing fluorescent capsule, fluorine-containing surfactant and polydimethylsiloxane to tetrahydrofuran, and disperse uniformly by ultrasonic oscillation to obtain a fluorescent anti-counterfeiting emulsion; wherein the mass ratio of the multi-color-changing fluorescent capsule, fluorine-containing surfactant and polydimethylsiloxane is 1:0.5-2:0.05-0.5; further preferably 1:1:0.2.

[0012] 2) Spray the fluorescent anti-counterfeiting emulsion onto a polyimide substrate, and dry at 60-150°C for 2-10 hours to obtain a multi-color-changing fluorescent anti-counterfeiting super-hydrophobic composite film. Further preferably, the reaction is at 120°C for 5 hours.

[0013] The fluorine-containing surfactant is one or more of perfluorohexylethyl sulfonic acid, hexafluoroisopropanol and perfluorooctyl ethyl acrylate.

[0014] The structural formula of 7-amino-4-methylcoumarin is as follows:

[0015]

[0016] The structural formula of indocyanine green is as follows:

[0017]

[0018] The 7-amino-4-methylcoumarin in the two-component fluorescent material is a blue fluorescent material with an emission spectrum between 375 and 480 nm. Indocyanine green (ICG) in the two-component fluorescent material is a near-infrared fluorescent material with an absorption peak near 780 nm and a maximum excitation wavelength near 815 nm. The emission spectrum of 7-amino-4-methylcoumarin and the absorption spectrum of ICG have little overlap, effectively preventing energy transfer between the two. Furthermore, hydrogen bonding between the polar functional groups of 7-amino-4-methylcoumarin and ICG inhibits intramolecular rotation, enhances intramolecular charge transfer, and increases the intensity of excited-state oscillators, resulting in stronger fluorescence and enhanced luminescence.

[0019] The above method has the following technical advantages:

[0020] The core of the multi-color fluorescent capsule prepared by the present invention is composed of 7-amino-4-methylcoumarin and indocyanine green, which effectively prevents energy transfer between the multi-component fluorescent materials, thereby achieving multi-color anti-counterfeiting. The shell of the multi-color fluorescent capsule prepared by the present invention is composed of polystyrene, which helps protect the fluorescent dye's luminescence process from external interference. The multi-color anti-counterfeiting luminescent composite film prepared by the present invention also has superhydrophobic properties, which further improves the stability of the composite film's fluorescence performance. The present invention uses a spray coating method to prepare the anti-counterfeiting superhydrophobic composite film, which simplifies the equipment and reduces costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The optical absorption spectra of 7-amino-4-methylcoumarin and indocyanine green.

[0022] Figure 2 This is the optical absorption spectrum of the multi-color fluorescent capsule.

[0023] Figure 3 The fluorescence spectra of 7-amino-4-methylcoumarin at different excitation wavelengths.

[0024] Figure 4 Fluorescence spectra of indocyanine green at different excitation wavelengths.

[0025] Figure 5 The fluorescence spectra of the fluorescent anti-counterfeiting emulsion prepared in Example 1 at different excitation wavelengths. DETAILED DESCRIPTION

[0026] In order to illustrate the present invention more clearly, the present invention is further described below in conjunction with embodiments. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0027] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods. The experimental materials, reagents, etc. used in the following experimental examples can be obtained through commercial channels or known experimental methods. Example 1:

[0028] (1) Preparation of fluorescent capsules

[0029] 1) Dissolve 30 mg of sodium lauryl sulfate, 9 mg of sodium bicarbonate, and 36 mg of polyvinylpyrrolidone in 30 mL of ultrapure water to prepare solution A.

[0030] 2) Dissolve 10 mg of 7-amino-4-methylcoumarin and 1 mg of indocyanine green in 0.5 mL of dichloromethane and mix with 1.1 mL (1 g) of styrene to prepare solution B.

[0031] 3) Solution A and Solution B were mixed and ultrasonically shaken at 0°C for 15 minutes. Then, 20 mg of potassium persulfate was added and the mixture was reacted at 80°C for 12 hours. The product was centrifuged and washed three times alternately with distilled water and ethanol to obtain multi-color fluorescent capsules.

[0032] (2) Preparation of multi-color fluorescent anti-counterfeiting super-hydrophobic composite films

[0033] 1) Add 30 mg of multi-color fluorescent capsules, 30 mg of perfluorohexyl ethyl sulfonic acid, and 6 mg of polydimethylsiloxane to 20 mL of tetrahydrofuran and disperse them evenly by ultrasonic vibration to obtain a fluorescent anti-counterfeiting emulsion.

[0034] 2) Spray the fluorescent anti-counterfeiting emulsion onto the polyimide substrate (about 1mL / cm 2 ), and dried at 120 °C for 5 hours to obtain a fluorescent anti-counterfeiting super-hydrophobic composite film with multiple color changes.

[0035] Example 2: The difference between this example and Example 1 is that the fluorinated surfactant used in step (2) is hexafluoroisopropanol, and the other treatment methods are consistent with Example 1.

[0036] Example 3: The difference between this example and Example 1 is that the amount of styrene used in step (1) is 0.25 mL (0.2 g), and the other treatment methods are consistent with Example 1.

[0037] Example 4: The difference between this example and Example 1 is that the amount of styrene used in step (1) is 5 mL (4.5 g), and the other treatment methods are consistent with Example 1.

[0038] Example 5: The difference between this example and Example 1 is that the amount of potassium persulfate used in step (1) is 8 mg, and the other treatment methods are consistent with Example 1.

[0039] Example 6: The difference between this example and Example 1 is that the amount of potassium persulfate used in step (1) is 40 mg, and the other treatment methods are consistent with Example 1.

[0040] Example 7: The difference between this example and Example 1 is that the amount of the multi-color fluorescent capsule used in step (2) is 10 mg, and the other processing methods are consistent with Example 1.

[0041] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the luminescent material used in step (1) is 7-amino-4-methylcoumarin, and indocyanine green is not used. The amount of 7-amino-4-methylcoumarin used is consistent with the amount of 7-amino-4-methylcoumarin used in Example 1, and the other treatment methods are consistent with Example 1.

[0042] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the luminescent material used in step (1) is indocyanine green, and 7-amino-4-methylcoumarin is not used. The amount of indocyanine green used is consistent with the amount of indocyanine green used in Example 1, and the other treatment methods are consistent with Example 1.

[0043] Comparative Example 3: The difference between this comparative example and Example 1 is that the amount of perfluorohexylethylsulfonic acid used in step (2) is 10 mg, and the other treatment methods are consistent with Example 1.

[0044] Comparative Example 4: The difference between this comparative example and Example 1 is that the amount of polydimethylsiloxane used in step (2) is 2 mg, and the other processing methods are consistent with Example 1.

[0045] Comparative Example 5: This comparative example differs from Example 1 in that polydimethylsiloxane is not used in step (2), and the amount of perfluorohexylethylsulfonic acid used is the sum of the masses of perfluorohexylethylsulfonic acid and polydimethylsiloxane in Example 1. Other treatment methods are consistent with Example 1.

[0046] Comparative Example 6: The difference between this comparative example and Example 1 is that perfluorohexylethylsulfonic acid is not used in step (2), and the amount of polydimethylsiloxane used is the sum of the masses of perfluorohexylethylsulfonic acid and polydimethylsiloxane in Example 1. Other processing methods are consistent with Example 1.

[0047] Comparative Example 7: The difference between this comparative example and Example 1 is that the drying temperature of the fluorescent anti-counterfeiting super-hydrophobic composite film in step (2) is 70°C, and the other treatment methods are consistent with Example 1.

[0048] Luminescence performance test: A fluorescence spectrometer (Hitachi, F-4500) was used in the test range of 200-900 nm. Luminescence performance.

[0049] Luminescence properties: The fluorescence intensity of the composite film prepared in Example 1 (before stability test) at 834 nm was used as a benchmark. Other luminescence properties were the ratio of the intensity of the measured fluorescence curve at 834 nm divided by the benchmark.

[0050] Color change performance test: Use light with a wavelength of 375nm and 810nm to irradiate the composite film respectively. If the composite film can show two colors respectively, it is considered to have color change performance.

[0051] Superhydrophobicity measurement: The contact angle test was performed using a JC2000D1 contact angle tester. The volume of the test liquid was 5 μL. Five sites on the film surface were tested and the average value was calculated as the water contact angle of the sample. If the contact angle was greater than 150 o , which is a super hydrophobic surface.

[0052] Heat resistance test: heat the composite film to 70 o After maintaining at C for 30 min, the water contact angle and color change performance were tested.

[0053] Abrasion resistance test: The composite film was dragged over 1200-grit sandpaper under a load of 50 g at a speed of 2 cm / s over a distance of 5 m. After the test, the water contact angle and luminescence properties were measured.

[0054] Bending resistance: After folding the composite film 1000 times, the water contact angle and color change performance were tested.

[0055] The test results are shown in Table 1 below:

[0056] Table 1

[0057]

[0058] As can be seen from Table 1, it can be known from Examples 1-2 that the composite film prepared by the method has not only the multi-color change characteristics for anti-counterfeiting, but also the super-hydrophobic characteristics, and also exhibits excellent stability. As can be known from the comparison between Examples 1-2 and Example 3, if the amount of styrene is too small, the outer structure of the capsule is fragile, and the stability of the fluorescent anti-counterfeiting composite film is reduced. As can be known from the comparison between Examples 1-2 and Example 4, if the amount of styrene is too large, the outer structure of the capsule is too thick, and the light-emitting performance of the fluorescent anti-counterfeiting composite film is weakened. It can be seen that the amount of styrene has an important influence on the performance of the fluorescent anti-counterfeiting composite film. As can be known from the comparison between Examples 1-2 and Examples 5-6, if the amount of potassium persulfate is too small or too large, it cannot effectively initiate the full polymerization of styrene or cause the molecular weight of polystyrene to decrease, resulting in the light-emitting performance and stability of the fluorescent anti-counterfeiting composite film being reduced. As can be known from the comparison between Examples 1-2 and Example 7, if the amount of fluorescent capsules is too small, the light-emitting performance of the fluorescent anti-counterfeiting composite film will be reduced. As can be known from Examples 1-2 and Comparative Examples 1-2, compared with the single-component fluorescent substance as the light-emitting material, the composite film prepared by the method has multi-color change characteristics, and the anti-counterfeiting effect is better. In addition, as can be known from Examples 1-2 and Comparative Example 2, compared with the composite film with a single-component indocyanine green as the light-emitting material, the hydrogen bond interaction in the composite film with a double-component 7-amino-4-methyl coumarin and indocyanine green as the light-emitting material weakens the intramolecular rotation of indocyanine green, and the light-emitting performance is better. As can be known from Examples 1-2 and Comparative Examples 3-6, the amount of perfluorohexylethyl sulfonic acid and polydimethylsiloxane has an important influence on the super-hydrophobic characteristics and stability performance of the composite film. As can be known from Examples 1-2 and Comparative Example 7, the curing temperature of polydimethylsiloxane also has a great influence on the stability of the composite film.

[0059] In combination Figure 1 and Figure 2 It can be known that the fluorescent capsules contain two light-emitting materials, 7-amino-4-methyl coumarin and indocyanine green. As can be known from Figure 3 and Figure 4 It can be known that even if the excitation wavelength of the two light-emitting materials, 7-amino-4-methyl coumarin and indocyanine green, is changed, the emission peak of the fluorescence spectrum will not change, indicating that the use of a single light-emitting material will not obtain a multi-color change anti-counterfeiting composite film. As can be known from Figure 5 It can be known that when 7-amino-4-methyl coumarin and indocyanine green are used at the same time, with the red shift of the excitation wavelength, the emission peak of the fluorescence spectrum also correspondingly red shifts, indicating that the use of different light to irradiate the composite film will make the composite film present different colors.

[0060] In summary, the composite film prepared by the method not only has super-hydrophobic and multi-color change characteristics, but also has excellent stability.

[0061] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with this patent can make slight changes or modifications to equivalent embodiments using the above technical content without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the solution of the present invention.

Claims

1. A multi-color fluorescent anti-counterfeiting super-hydrophobic composite film, characterized in that: The multi-color fluorescent anti-counterfeiting super-hydrophobic composite film is prepared by blending multi-color fluorescent capsules and a hydrophobic modifier into a fluorescent anti-counterfeiting emulsion, which is sprayed on the surface of a polymer matrix to obtain a multi-color fluorescent composite film with super-hydrophobic properties; the multi-color fluorescent capsules are prepared by encapsulating a mixture of 7-amino-4-methylcoumarin and indocyanine green in polystyrene; the hydrophobic modifier is a fluorine-containing surfactant and polydimethylsiloxane.

2. The multi-color fluorescent anti-counterfeiting super-hydrophobic composite film according to claim 1, characterized in that: The steps of preparing the multi-color fluorescent capsule are as follows: (1) Dissolve sodium lauryl sulfate, sodium bicarbonate and polyvinyl pyrrolidone in ultrapure water to prepare solution A; (2) A mixture of 7-amino-4-methylcoumarin and indocyanine green was added to dichloromethane, dissolved, and then mixed with styrene to prepare solution B; (3) Solution A and solution B are mixed, ultrasonically shaken at low temperature, and potassium persulfate is added. The mixture is heated for reaction. The reaction product is centrifuged and washed to obtain a multi-color fluorescent capsule.

3. The multi-color fluorescent anti-counterfeiting super-hydrophobic composite film according to claim 2, characterized in that: In step (1), the mass ratio of sodium lauryl sulfate, sodium bicarbonate and polyvinyl pyrrolidone is 1:0.1-0.8:0.6-2.

6.

4. The multi-color fluorescent anti-counterfeiting super-hydrophobic composite film according to claim 2, characterized in that: In step (2), the mass ratio of 7-amino-4-methylcoumarin, indocyanine green and styrene is 1:0.02-0.2:30-200.

5. The multi-color fluorescent anti-counterfeiting super-hydrophobic composite film according to claim 2, characterized in that: In step (2), the mass ratio of 7-amino-4-methylcoumarin, indocyanine green and styrene is 1:0.1:90-110.

6. The multi-color fluorescent anti-counterfeiting super-hydrophobic composite film according to claim 2, characterized in that: The mass ratio of sodium lauryl sulfate, 7-amino-4-methylcoumarin and potassium persulfate is 30:10:5-50; the temperature of the heating reaction in step (3) is 50-100° C. and the time is 5-30 hours.

7. The method for preparing the multi-color fluorescent anti-counterfeiting super-hydrophobic composite film according to claim 1, wherein: (1) Adding multi-color fluorescent capsules, fluorinated surfactants, and polydimethylsiloxane into tetrahydrofuran, and uniformly dispersing them by ultrasonic vibration to obtain a fluorescent anti-counterfeiting emulsion; (2) Spraying the fluorescent anti-counterfeiting emulsion onto the surface of a polymer matrix, heating and drying, and preparing a fluorescent anti-counterfeiting super-hydrophobic composite film with multiple color changes; the polymer matrix is ​​a polyimide matrix.

8. The method for preparing the multi-color fluorescent anti-counterfeiting super-hydrophobic composite film according to claim 7, wherein: The fluorinated surfactant in step (1) is one or more of perfluorohexyl ethyl sulfonic acid, hexafluoroisopropanol, and perfluorooctyl ethyl acrylate.

9. The method for preparing the multi-color fluorescent anti-counterfeiting super-hydrophobic composite film according to claim 7, wherein: In step (1), the mass ratio of the fluorescent capsule, the fluorinated surfactant, and the polydimethylsiloxane is 1:0.5-2:0.05-0.

5.

10. The method for preparing the multi-color fluorescent anti-counterfeiting super-hydrophobic composite film according to claim 7, characterized in that: In step (2), the drying temperature is 60-150° C. and the drying time is 2-10 hours.

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