Ultraviolet fluorescent anti-counterfeiting film based on multilayer optical variability and preparation method of ultraviolet fluorescent anti-counterfeiting film

Abstract

The invention relates to the technical field of preparation of anti-counterfeiting films, and particularly discloses an ultraviolet fluorescent anti-counterfeiting film based on multi-layer optical variability and a preparation method of the ultraviolet fluorescent anti-counterfeiting film. The ultraviolet fluorescent anti-counterfeiting film based on multilayer optical variability comprises a film substrate layer, a first optical variability layer and a second optical variability layer, wherein the first optical variable layer and the second optical variable layer are located on the two sides of the thin film base material layer respectively; the first optical variable layer and the second optical variable layer respectively comprise rhodamine B, fluorescein sodium and europium oxide. According to the ultraviolet fluorescent anti-counterfeiting film, the first light-variable layer and the second light-variable layer which contain light-variable materials such as rhodamine B, fluorescein sodium and europium oxide are arranged on the two sides of the film base material layer, so that the prepared multi-layer light-variable ultraviolet fluorescent anti-counterfeiting film has relatively short ultraviolet radiation color change reaction time; wide application prospects are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of anti-counterfeiting film preparation, and particularly relates to a multi-layer light-variable ultraviolet fluorescence anti-counterfeiting film and a preparation method thereof. Background Art

[0002] With the rapid development of the commodity economy and the deep integration of global trade, anti-counterfeiting technology has become an important means to ensure product safety, maintain brand value, and combat counterfeiting and shoddy products. Traditional anti-counterfeiting technologies such as holographic images and laser engraving have gradually exposed defects such as easy replication and high recognition thresholds. To address this challenge, the development of new anti-counterfeiting materials with high security, easy recognition, and difficulty in replication has become one of the current research hotspots. For example, Chinese invention patent CN117510930A discloses a preparation method and application of a flexible ultraviolet fluorescence anti-counterfeiting composite film; its preparation steps include: synthesizing a precursor; preparing hexagonal boron nitride fluorescent powder by subjecting the precursor to high-temperature pyrolysis, washing, and drying; and compounding the hexagonal boron nitride fluorescent powder with a polymer to obtain a flexible ultraviolet fluorescence anti-counterfeiting composite film. The flexible ultraviolet fluorescence anti-counterfeiting composite film obtained by this invention has good chemical stability, flexibility, ductility, concealability, and conformability, can be well hidden under sunlight, but can brightly display the produced pattern under ultraviolet light, and can be applied to optical anti-counterfeiting and optical information encryption, etc., and has broad application prospects.

[0003] The inventors found in their research that although the ultraviolet fluorescence anti-counterfeiting film prepared by the prior art can achieve good luminescence under ultraviolet light; however, its ultraviolet irradiation color change reaction time is relatively long, and the sensitivity is not high and needs further improvement. Summary of the Invention

[0004] In order to overcome at least one of the technical problems existing in the prior art, the present invention first provides a multi-layer light-variable ultraviolet fluorescence anti-counterfeiting film and a preparation method thereof.

[0005] The present invention first provides a multi-layer light-variable ultraviolet fluorescence anti-counterfeiting film, which includes a film substrate layer, a first light-variable layer, and a second light-variable layer; wherein, the first light-variable layer and the second light-variable layer are respectively located on both sides of the film substrate layer;

[0006] The first light-variable layer and the second light-variable layer respectively contain rhodamine B, sodium fluorescein, and europium oxide.

[0007] The present invention provides a brand-new multi-layer light-variable ultraviolet fluorescence anti-counterfeiting film. By providing a first light-variable layer and a second light-variable layer containing light-variable materials such as rhodamine B, sodium fluorescein, and europium oxide on both sides of the film substrate layer, the prepared multi-layer light-variable ultraviolet fluorescence anti-counterfeiting film has a short ultraviolet irradiation color change reaction time.

[0008] Preferably, the weight ratio of rhodamine B, sodium fluorescein and europium oxide in the first photovariable layer and the second photovariable layer is 3-6:3-6:1-3.

[0009] Most preferably, the weight ratio of rhodamine B, sodium fluorescein and europium oxide in the first photovariable layer and the second photovariable layer is 5:5:2.

[0010] Preferably, the thin film substrate layer is prepared from the following components in parts by weight: 80-100 parts of polyvinyl chloride resin; 10-20 parts of mica powder.

[0011] Preferably, the thin film substrate layer is prepared from the following components in parts by weight: 85 parts of polyvinyl chloride resin; 15 parts of mica powder.

[0012] Preferably, the mica powder is modified mica powder;

[0013] The modified mica powder is prepared by the following method:

[0014] (1) Take mica powder, soak it in acid, and after the soaking is completed, take out the mica powder and wash it until neutral to obtain acid-treated mica powder;

[0015] (2) Add the acid-treated mica powder to water, and after dispersing it evenly, obtain an acid-treated mica powder dispersion;

[0016] (3) Add hafnium tetrachloride and yttrium chloride to the acid-treated mica powder dispersion and stir evenly, then add sodium hydroxide, stir and react for 3-5 h, and then perform solid-liquid separation to obtain a solid mixture;

[0017] (4) Calcinate the solid mixture at 800-1000 °C for 2-4 h; after the calcination is completed, take the calcined solid to obtain the modified mica powder.

[0018] The inventors surprisingly found in further research that in the thin film substrate layer of the ultraviolet fluorescence anti-counterfeiting film based on multi-layer photovariable, adding the modified mica powder prepared by the above method of the present invention can significantly shorten the ultraviolet irradiation color change reaction time of the ultraviolet fluorescence anti-counterfeiting film based on multi-layer photovariable of the present invention compared with adding unmodified mica powder.

[0019] The inventors also found in their research that in step (3) of modifying mica powder, hafnium tetrachloride and yttrium chloride must be added simultaneously and stirred to modify mica powder. The modified mica powder obtained in this way can significantly shorten the ultraviolet irradiation discoloration reaction time of the ultraviolet fluorescent anti-counterfeiting film based on multi-layer light change of the present invention compared to adding unmodified mica powder. However, if only hafnium tetrachloride or only yttrium chloride is added and stirred to modify mica powder in step (3) of modifying mica powder, the modified mica powder obtained cannot significantly shorten the ultraviolet irradiation discoloration reaction time of the ultraviolet fluorescent anti-counterfeiting film based on multi-layer light change of the present invention compared to adding unmodified mica powder.

[0020] Preferably, the weight ratio of the acid-treated mica powder to water in step (2) is 1:5 to 15;

[0021] Most preferably, the weight ratio of the acid-treated mica powder to water in step (2) is 1:9.

[0022] Preferably, the weight ratio of the acid-treated mica powder dispersion to hafnium tetrachloride, yttrium chloride and sodium hydroxide in step (3) is 10:0.1 to 0.2:0.08 to 0.12:0.1 to 1.5;

[0023] Most preferably, the weight ratio of the acid-treated mica powder dispersion to hafnium tetrachloride, yttrium chloride and sodium hydroxide in step (3) is 10:0.16:0.1:0.14.

[0024] Preferably, the method for preparing the modified mica powder further comprises the following steps:

[0025] Put the calcined solid into the modification liquid, stir for 1 to 3 hours, then separate the solid, and dry it to obtain the modified mica powder.

[0026] The modification liquid refers to an aqueous solution containing cocamidopropylamine oxide and sodium dodecyl diphenyl ether disulfonate; wherein, the weight ratio of cocamidopropylamine oxide, sodium dodecyl diphenyl ether disulfonate and water is 10 to 20:5 to 10:100.

[0027] Most preferably, the weight ratio of cocamidopropylamine oxide, sodium dodecyl diphenyl ether disulfonate and water is 13:7:100.

[0028] The inventors also surprisingly found in further research that during the preparation of the modified mica powder, the modified mica powder obtained by further putting the calcined solid into an aqueous solution containing both cocamidopropylamine oxide and sodium dodecyl diphenyl ether disulfonate for modification treatment can further significantly shorten the ultraviolet irradiation discoloration reaction time of the ultraviolet fluorescent anti-counterfeiting film based on multi-layer light change of the present invention.

[0029] The inventors also found that during the preparation of the modified mica powder, only when the calcined solid is further put into an aqueous solution containing both cocamidopropylamine oxide and sodium dodecyl diphenyl ether disulfonate for modification treatment can the obtained modified mica powder further significantly shorten the UV irradiation discoloration reaction time of the UV fluorescent anti-counterfeiting film based on multi-layer light change of the present invention; however, the modified mica powder obtained by putting it into an aqueous solution containing only a single cocamidopropylamine oxide or only a single sodium dodecyl diphenyl ether disulfonate for modification treatment cannot further significantly shorten the UV irradiation discoloration reaction time of the UV fluorescent anti-counterfeiting film based on multi-layer light change of the present invention.

[0030] The present invention also provides a preparation method of the above-mentioned UV fluorescent anti-counterfeiting film based on multi-layer light change, which is characterized by comprising the following steps:

[0031] (1) Mix the raw material polyvinyl chloride resin of the substrate layer with mica powder evenly to obtain a mixture, put the mixture into a twin-screw extruder for melt extrusion, and then cool and shape it through a cooling roller to make a film substrate layer;

[0032] (2) Spray a dispersion liquid containing rhodamine B, sodium fluorescein and europium oxide on both sides of the film substrate layer with a spray gun, and obtain a UV fluorescent anti-counterfeiting film based on multi-layer light change containing a first light change layer and a second light change layer after drying.

[0033] Preferably, the dispersion liquid containing rhodamine B, sodium fluorescein and europium oxide refers to an ethanol dispersion liquid containing rhodamine B, sodium fluorescein and europium oxide; wherein, the weight ratio of rhodamine B, sodium fluorescein, europium oxide to ethanol is 3-6:3-6:1-3:30-50.

[0034] Most preferably, the weight ratio of rhodamine B, sodium fluorescein, europium oxide to ethanol is 5:5:2:40.

[0035] Preferably, the ethanol refers to an ethanol aqueous solution with an ethanol volume fraction of 95%.

[0036] Preferably, the thickness of the film substrate layer is 50-100 μm; the thicknesses of the first light change layer and the second light change layer are 5-30 μm respectively;

[0037] Most preferably, the thickness of the film substrate layer is 80 μm; the thicknesses of the first light change layer and the second light change layer are 10 μm respectively.

[0038] Beneficial effects: The present invention provides a brand-new multilayer photovariable ultraviolet fluorescent anti-counterfeiting film. By providing a first photovariable layer and a second photovariable layer containing photovariable materials such as rhodamine B, sodium fluorescein, and europium oxide on both sides of the thin film substrate layer, the prepared multilayer photovariable ultraviolet fluorescent anti-counterfeiting film has a short ultraviolet irradiation color-changing reaction time and broad application prospects. Specific embodiments

[0039] The following specific embodiments are used to further explain the present invention, but the embodiments do not limit the present invention in any form.

[0040] In the following embodiments, the polyvinyl chloride resin used is the polyvinyl chloride resin with the brand SG-8 produced by Xinjiang Tianye; the remaining raw materials whose sources are not specified are conventional raw materials that those skilled in the art can obtain through conventional channels.

[0041] Example 1 Preparation of a multilayer photovariable ultraviolet fluorescent anti-counterfeiting film

[0042] The multilayer photovariable ultraviolet fluorescent anti-counterfeiting film described above includes a thin film substrate layer, a first photovariable layer, and a second photovariable layer; among them, the first photovariable layer and the second photovariable layer are respectively located on both sides of the thin film substrate layer; the thickness of the thin film substrate layer is 80 μm; the thicknesses of the first photovariable layer and the second photovariable layer are both 10 μm.

[0043] The thin film substrate layer is prepared from the following components in parts by weight: 85 parts of polyvinyl chloride resin; 15 parts of mica powder.

[0044] The preparation method of the multilayer photovariable ultraviolet fluorescent anti-counterfeiting film described above includes the following steps:

[0045] (1) Mix the raw materials of the thin film substrate layer, polyvinyl chloride resin and mica powder, evenly according to the above parts by weight to obtain a mixture. Put the mixture into a twin-screw extruder for melt extrusion, and then cool and shape it through a cooling roller to make a thin film substrate layer with a thickness of 80 μm;

[0046] (2) Spray a dispersion liquid containing rhodamine B, sodium fluorescein, and europium oxide on both sides of the thin film substrate layer with a spray gun, and after drying, obtain a multilayer photovariable ultraviolet fluorescent anti-counterfeiting film with a first photovariable layer (10 μm thick) and a second photovariable layer (10 μm thick);

[0047] The dispersion liquid containing rhodamine B, sodium fluorescein, and europium oxide mentioned in step (2) refers to an ethanol dispersion liquid containing rhodamine B, sodium fluorescein, and europium oxide; among them, the weight ratio of rhodamine B, sodium fluorescein, europium oxide to ethanol is 5:5:2:40; the ethanol mentioned refers to an ethanol aqueous solution with an ethanol volume fraction of 95%.

[0048] Preparation of UV Fluorescent Anti-Counterfeiting Film Based on Multilayer Optical Variation - Example 2

[0049] The difference between Example 2 and Example 1 is that the mica powder in the film substrate layer is modified mica powder; the rest is the same as Example 1.

[0050] The modified mica powder is prepared by the following method:

[0051] (1) Take mica powder and soak it in acid with a weight 5 times that of the mica powder. After soaking, take out the mica powder and wash it until neutral to obtain acid-treated mica powder; the acid refers to a sulfuric acid aqueous solution with a sulfuric acid mass fraction of 80%.

[0052] (2) Add the acid-treated mica powder to water and disperse it evenly to obtain an acid-treated mica powder dispersion; among them, the weight ratio of the acid-treated mica powder to water is 1:9.

[0053] (3) Add hafnium tetrachloride and yttrium chloride to the acid-treated mica powder dispersion and stir evenly, then add sodium hydroxide and stir and react for 4 h, and then perform solid-liquid separation to obtain a solid mixture; among them, the weight ratio of the acid-treated mica powder dispersion to hafnium tetrachloride, yttrium chloride, and sodium hydroxide is 10:0.16:0.1:0.14.

[0054] (4) Bake the solid mixture at 95 °C for 3 h; after baking, take the baked solid to obtain the modified mica powder.

[0055] Preparation of UV Fluorescent Anti-Counterfeiting Film Based on Multilayer Optical Variation - Example 3

[0056] The difference between Example 3 and Example 2 is that the preparation method of the modified mica powder in the film substrate layer is different.

[0057] The modified mica powder is prepared by the following method:

[0058] (1) Take mica powder and soak it in acid with a weight 5 times that of the mica powder. After soaking, take out the mica powder and wash it until neutral to obtain acid-treated mica powder; the acid refers to a sulfuric acid aqueous solution with a sulfuric acid mass fraction of 80%.

[0059] (2) Add the acid-treated mica powder to water and disperse it evenly to obtain an acid-treated mica powder dispersion; among them, the weight ratio of the acid-treated mica powder to water is 1:9.

[0060] (3) Add hafnium tetrachloride and yttrium chloride to the acid-treated mica powder dispersion and stir evenly, then add sodium hydroxide and stir and react for 4 h, and then perform solid-liquid separation to obtain a solid mixture; among them, the weight ratio of the acid-treated mica powder dispersion to hafnium tetrachloride, yttrium chloride, and sodium hydroxide is 10:0.16:0.1:0.14.

[0061] (4) Roast the solid mixture at 95 °C for 3 h; after roasting, a roasted solid is obtained;

[0062] (5) Put the roasted solid into the modification liquid, stir for 2 h, then separate the solid, and after drying, the modified mica powder is obtained;

[0063] Among them, the modification liquid in step (5) refers to an aqueous solution containing cocamidopropylamine oxide and dodecyl diphenyl ether disulfonate; among them, the weight ratio of cocamidopropylamine oxide, dodecyl diphenyl ether disulfonate and water is 13:7:100.

[0064] Preparation of ultraviolet fluorescence anti-counterfeiting film based on multilayer optical variable for Comparative Example 1

[0065] The difference between Comparative Example 1 and Example 2 is that the mica powder in the film substrate layer is modified mica powder; the others are the same as in Example 1.

[0066] The modified mica powder is prepared by the following method:

[0067] (1) Take mica powder, soak it in an acid with a weight 5 times that of the mica powder, and after soaking, take out the mica powder and wash it until neutral to obtain acid-treated mica powder; the acid refers to an aqueous sulfuric acid solution with a sulfuric acid mass fraction of 80%;

[0068] (2) Add the acid-treated mica powder to water, and after dispersing evenly, an acid-treated mica powder dispersion is obtained; among them, the weight ratio of the acid-treated mica powder to water is 1:9;

[0069] (3) Add hafnium tetrachloride to the acid-treated mica powder dispersion and stir evenly, then add sodium hydroxide, stir and react for 4 h, and then perform solid-liquid separation to obtain a solid mixture; among them, the weight ratio of the acid-treated mica powder dispersion, hafnium tetrachloride and sodium hydroxide is 10:0.26:0.14;

[0070] (4) Roast the solid mixture at 95 °C for 3 h; after roasting, take the roasted solid to obtain the modified mica powder.

[0071] Preparation of ultraviolet fluorescence anti-counterfeiting film based on multilayer optical variable for Comparative Example 2

[0072] The difference between Comparative Example 2 and Example 2 is that the mica powder in the film substrate layer is modified mica powder; the others are the same as in Example 1.

[0073] The modified mica powder is prepared by the following method:

[0074] (1) Take mica powder, soak it in an acid with a weight 5 times that of the mica powder, and after soaking, take out the mica powder and wash it until neutral to obtain acid-treated mica powder; the acid refers to an aqueous sulfuric acid solution with a sulfuric acid mass fraction of 80%;

[0075] (2) Add the acid-treated mica powder into water, and obtain the acid-treated mica powder dispersion after uniform dispersion; wherein, the weight ratio of the acid-treated mica powder to water is 1:9;

[0076] (3) Add yttrium chloride into the acid-treated mica powder dispersion and stir evenly, then add sodium hydroxide, stir and react for 4 h, and then perform solid-liquid separation to obtain a solid mixture; wherein, the weight ratio of the acid-treated mica powder dispersion to yttrium chloride and sodium hydroxide is 10:0.26:0.14;

[0077] (4) Calcine the solid mixture at 95 °C for 3 h; after the calcination is completed, take the calcined solid to obtain the modified mica powder.

[0078] Preparation of UV fluorescence anti-counterfeiting film based on multi-layer optical variable for Comparative Example 3

[0079] The difference between Comparative Example 3 and Example 3 lies in the different preparation methods of the modified mica powder in the film substrate layer.

[0080] The modified mica powder is prepared by the following method:

[0081] (1) Take mica powder, soak it in acid with a weight 5 times that of the mica powder, and take out the mica powder after soaking and wash it until neutral to obtain acid-treated mica powder; the acid refers to a sulfuric acid aqueous solution with a sulfuric acid mass fraction of 80%;

[0082] (2) Add the acid-treated mica powder into water, and obtain the acid-treated mica powder dispersion after uniform dispersion; wherein, the weight ratio of the acid-treated mica powder to water is 1:9;

[0083] (3) Add hafnium tetrachloride and yttrium chloride into the acid-treated mica powder dispersion and stir evenly, then add sodium hydroxide, stir and react for 4 h, and then perform solid-liquid separation to obtain a solid mixture; wherein, the weight ratio of the acid-treated mica powder dispersion to hafnium tetrachloride, yttrium chloride and sodium hydroxide is 10:0.16:0.1:0.14;

[0084] (4) Calcine the solid mixture at 95 °C for 3 h; after the calcination is completed, obtain the calcined solid;

[0085] (5) Put the calcined solid into the modification liquid, stir for 2 h, then separate the solid, and dry it to obtain the modified mica powder;

[0086] Wherein, the modification liquid in step (5) refers to an aqueous solution containing cocamidopropylamine oxide; wherein, the weight ratio of cocamidopropylamine oxide to water is 20:100.

[0087] Preparation of UV fluorescence anti-counterfeiting film based on multi-layer optical variable for Comparative Example 4

[0088] The difference between Comparative Example 4 and Example 3 lies in the different preparation methods of the modified mica powder in the film substrate layer.

[0089] The modified mica powder is prepared by the following method:

[0090] (1) Take mica powder and soak it in an acid with a weight 5 times that of the mica powder. After the soaking is completed, take out the mica powder and wash it until neutral to obtain acid-treated mica powder. The acid refers to a sulfuric acid aqueous solution with a sulfuric acid mass fraction of 80%.

[0091] (2) Add the acid-treated mica powder to water and disperse it evenly to obtain an acid-treated mica powder dispersion. Among them, the weight ratio of the acid-treated mica powder to water is 1:9.

[0092] (3) Add hafnium tetrachloride and yttrium chloride to the acid-treated mica powder dispersion and stir evenly. Then add sodium hydroxide and stir and react for 4 h, and then perform solid-liquid separation to obtain a solid mixture. Among them, the weight ratio of the acid-treated mica powder dispersion to hafnium tetrachloride, yttrium chloride, and sodium hydroxide is 10:0.16:0.1:0.14.

[0093] (4) Calcinate the solid mixture at 95 °C for 3 h; after the calcination is completed, obtain a calcined solid.

[0094] (5) Put the calcined solid into the modification liquid, stir for 2 h, then separate the solid, and dry it to obtain the modified mica powder.

[0095] Among them, the modification liquid in step (5) refers to an aqueous solution containing sodium dodecyl diphenyl ether disulfonate. Among them, the weight ratio of sodium dodecyl diphenyl ether disulfonate to water is 20:100.

[0096] Experimental Example 1

[0097] Put the ultraviolet fluorescence anti-counterfeiting films based on multi-layer light change prepared in Examples 1 to 3 and Comparative Examples 1 to 4 into a test chamber respectively, and record the ultraviolet irradiation discoloration reaction time under the sunlight simulator light source. The test results are shown in Table 1.

[0098]

[0099] As can be seen from the experimental results in Table 1, for the ultraviolet fluorescence anti-counterfeiting film based on multi-layer light change prepared in Example 1, its ultraviolet irradiation discoloration reaction time is 15.4 s, and it has good sensitivity.

[0100] As can be seen from the experimental results in Table 1, the ultraviolet irradiation discoloration reaction time of the ultraviolet fluorescent anti-counterfeiting film based on multi-layer light change prepared in Example 2 is much shorter than that of the ultraviolet fluorescent anti-counterfeiting film based on multi-layer light change prepared in Example 1; this shows that: in the thin film substrate layer of the ultraviolet fluorescent anti-counterfeiting film based on multi-layer light change, adding the modified mica powder prepared by the method described in the present invention can significantly shorten the ultraviolet irradiation discoloration reaction time of the ultraviolet fluorescent anti-counterfeiting film based on multi-layer light change of the present invention compared with adding unmodified mica powder.

[0101] As can be seen from the experimental results in Table 1, the ultraviolet irradiation discoloration reaction times of the ultraviolet fluorescent anti-counterfeiting films based on multi-layer light change prepared in Comparative Examples 1 and 2 are reduced compared with that of the ultraviolet fluorescent anti-counterfeiting film based on multi-layer light change prepared in Example 1, but the reduction amplitude is not large; this shows that: in step (3) of modifying mica powder, the modified mica powder obtained by stirring mica powder with hafnium tetrachloride and yttrium chloride added simultaneously can significantly shorten the ultraviolet irradiation discoloration reaction time of the ultraviolet fluorescent anti-counterfeiting film based on multi-layer light change of the present invention compared with adding unmodified mica powder; however, the modified mica powder obtained by stirring mica powder with only a single hafnium tetrachloride or only a single yttrium chloride added in step (3) of modifying mica powder cannot significantly shorten the ultraviolet irradiation discoloration reaction time of the ultraviolet fluorescent anti-counterfeiting film based on multi-layer light change of the present invention compared with adding unmodified mica powder.

[0102] As can be seen from the experimental results in Table 1, the ultraviolet irradiation discoloration reaction time of the ultraviolet fluorescent anti-counterfeiting film based on multi-layer light change prepared in Example 3 is further much shorter than that of the ultraviolet fluorescent anti-counterfeiting film based on multi-layer light change prepared in Example 2; this shows that: in the preparation process of the modified mica powder, the modified mica powder obtained by further putting the calcined solid into an aqueous solution containing both cocamidopropylamine oxide and dodecyl diphenyl ether disulfonate for modification can further significantly shorten the ultraviolet irradiation discoloration reaction time of the ultraviolet fluorescent anti-counterfeiting film based on multi-layer light change of the present invention.

[0103] As can be seen from the experimental results in Table 1, for the UV fluorescent anti-counterfeiting films based on multi-layer optical variation prepared in Comparative Examples 3 and 4, although the UV irradiation discoloration reaction time is reduced compared with the UV fluorescent anti-counterfeiting film based on multi-layer optical variation prepared in Example 2, the reduction amplitude is not large. This shows that: in the preparation process of the modified mica powder, only when the calcined solid is further put into an aqueous solution containing both cocamidopropylamine oxide and sodium dodecyl diphenyl ether disulfonate for modification treatment can the modified mica powder be obtained, which can further significantly shorten the UV irradiation discoloration reaction time of the UV fluorescent anti-counterfeiting film based on multi-layer optical variation of the present invention; however, the modified mica powder obtained by putting it into an aqueous solution containing only a single cocamidopropylamine oxide or only a single sodium dodecyl diphenyl ether disulfonate for modification treatment cannot further significantly shorten the UV irradiation discoloration reaction time of the UV fluorescent anti-counterfeiting film based on multi-layer optical variation of the present invention.

Claims

1. A multi-layer optically variable ultraviolet fluorescent anti-counterfeiting film, characterized in that: It comprises a film substrate layer, a first light-variable layer and a second light-variable layer; wherein the first light-variable layer and the second light-variable layer are respectively located on two sides of the film substrate layer; The first light-variable layer and the second light-variable layer respectively contain rhodamine B, sodium fluorescein and europium oxide.

2. The multi-layer optically variable ultraviolet fluorescent anti-counterfeiting film according to claim 1, characterized in that: The weight ratio of rhodamine B, sodium fluorescein and europium oxide in the first light-variable layer and the second light-variable layer is 3-6:3-6:1-3.

3. The multi-layer light-variable ultraviolet fluorescent anti-counterfeiting film according to claim 1, characterized in that: The weight ratio of rhodamine B, sodium fluorescein and europium oxide in the first light-variable layer and the second light-variable layer is 5:5:

2.

4. The multi-layer light-variable ultraviolet fluorescent anti-counterfeiting film according to claim 1, characterized in that: The film substrate layer is prepared from the following components in parts by weight: 80 to 100 parts of polyvinyl chloride resin and 10 to 20 parts of mica powder.

5. The multi-layer optically variable ultraviolet fluorescent anti-counterfeiting film according to claim 1, characterized in that: The film substrate layer is prepared from the following components in parts by weight: 85 parts of polyvinyl chloride resin and 15 parts of mica powder.

6. The multi-layer optically variable ultraviolet fluorescent anti-counterfeiting film according to claim 1, characterized in that: The mica powder is modified mica powder; The modified mica powder is prepared by the following method: (1) taking mica powder, soaking it in acid, taking out the mica powder after soaking, washing it to neutrality to obtain acid-treated mica powder; (2) adding the acid-treated mica powder into water and dispersing the mixture evenly to obtain an acid-treated mica powder dispersion; (3) adding hafnium tetrachloride and yttrium chloride to the acid-treated mica powder dispersion and stirring evenly, then adding sodium hydroxide, stirring and reacting for 3 to 5 hours, and then performing solid-liquid separation to obtain a solid mixture; (4) calcining the solid mixture at 800-1000° C. for 2-4 hours; after calcination, taking the calcined solid to obtain the modified mica powder.

7. The multi-layer optically variable ultraviolet fluorescent anti-counterfeiting film according to claim 6, characterized in that: In step (2), the weight ratio of the acid-treated mica powder to water is 1:5 to 15; Most preferably, the weight ratio of the acid-treated mica powder to water in step (2) is 1:

9.

8. The multi-layer light-variable ultraviolet fluorescent anti-counterfeiting film according to claim 6, characterized in that: In step (3), the weight ratio of the acid-treated mica powder dispersion to hafnium tetrachloride, yttrium chloride and sodium hydroxide is 10:0.1-0.2:0.08-0.12:0.1-1.5; Most preferably, in step (3), the weight ratio of the acid-treated mica powder dispersion to hafnium tetrachloride, yttrium chloride and sodium hydroxide is 10:0.16:0.1:0.

14.

9. The method for preparing a multi-layer optically variable ultraviolet fluorescent anti-counterfeiting film according to any one of claims 1 to 8, characterized in that: The following steps are included: (1) uniformly mixing polyvinyl chloride resin and mica powder, raw materials of the substrate layer, to obtain a mixture, placing the mixture into a twin-screw machine for melt extrusion, and then cooling and shaping the mixture through a cooling roller to obtain a film substrate layer; (2) Spraying a dispersion containing rhodamine B, sodium fluorescein and europium oxide on both sides of the film substrate layer with a spray gun, and obtaining a multi-layer optically variable ultraviolet fluorescent anti-counterfeiting film containing a first optically variable layer and a second optically variable layer after drying.

10. The method for preparing the multi-layer optically variable ultraviolet fluorescent anti-counterfeiting film according to claim 9, characterized in that: The dispersion containing rhodamine B, sodium fluorescein and europium oxide described in step (1) refers to an ethanol dispersion containing rhodamine B, sodium fluorescein and europium oxide; wherein the weight ratio of rhodamine B, sodium fluorescein, europium oxide and ethanol is 3-6:3-6:1-3:30-50.

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