CN115368606A

CN115368606A - Preparation method and application of double anti-counterfeiting polymer film

Info

Publication number: CN115368606A
Application number: CN202211307054.3A
Authority: CN
Inventors: 吴思; 许国锋
Original assignee: University of Science and Technology of China USTC
Current assignee: University of Science and Technology of China USTC
Priority date: 2022-10-25
Filing date: 2022-10-25
Publication date: 2022-11-22
Anticipated expiration: 2042-10-25
Also published as: CN115368606B

Abstract

The invention discloses a preparation method and application of a double anti-counterfeiting polymer film, wherein the polymer film is prepared by copolymerizing monomer molecules containing liquid crystal elements and monomer molecules containing a styryl pyrene structure. The polymer film can be used for preparing an anti-counterfeiting material, and the anti-counterfeiting material has a double anti-counterfeiting function by writing anti-counterfeiting information twice by using visible light with a wavelength range of 400-470 nanometers. In the invention, the anti-counterfeiting information is respectively written in the surface layer and the deep layer by visible light irradiation under the assistance of different mask plates, and the surface layer information and the deep layer information are respectively read out by an LED lamp excitation and a polarizing microscope (polaroid). Wherein, the deep information is written again in the area written with the surface layer information; the deeply written information can be well hidden in the surface information. The double anti-counterfeiting technology has novel thought, simple film preparation process, low cost and high information encryption quality.

Description

Preparation method and application of double anti-counterfeiting polymer film

Technical Field

The invention belongs to the technical field of optical anti-counterfeiting, and particularly relates to a preparation method and application of a double anti-counterfeiting polymer film.

Background

In recent years, security materials, particularly security films, have been widely used. However, with the enhancement of counterfeit imitation capability, there is a need to develop new anti-counterfeiting technologies and products thereof, such as multiple anti-counterfeiting polymer films based on fluorescence and liquid crystal technologies.

For the fluorescent anti-counterfeiting technology, CN 112679692A introduces the structure of anthracene molecules into a polymer system, and utilizes the characteristics of light-controlled dimerization reaction and dimerization reaction of anthracene molecules to change fluorescence, so as to realize the fluorescent anti-counterfeiting technology capable of repeatedly writing and erasing, but the anti-counterfeiting film can only write one kind of information each time, and the information encryption quality is low. Furthermore, the chemical-a European Journal 2020, 26, 478-484 has proved that the anthracene molecular dimer structure is depolymerized after being heated, which can cause the distortion of encrypted information; therefore, the thermal stability of the security film is insufficient, thereby limiting the range of applications.

For the liquid crystal anti-counterfeiting technology, for example, CN 112327522A provides a liquid crystal anti-counterfeiting film based on temperature response, which controls the polymerization of liquid crystal monomers by regulating the ultraviolet light irradiation integrated quantity to regulate the density of the formation of the liquid crystal polymer network, and realizes the partition distribution of the content of the liquid crystal polymer network, so that liquid crystal molecules in different areas show different arrangement modes along with the temperature change, thereby realizing the temperature response of the liquid crystal film pattern. However, the realization of the liquid crystal film anti-counterfeiting function depends on the change of temperature, so the technology can not be applied to products requiring a constant temperature process, and in addition, the technical process for realizing the liquid crystal orientation is also complex, thereby limiting the application range of the technology.

The multiple anti-counterfeiting technology is an important direction for the development of the anti-counterfeiting technology due to the high information encryption degree. For example, in a representative CN 102848667B patent, by means of orientation of liquid crystal molecules and a holographic technique, image-text information and information of which color changes with an observation angle on an anti-counterfeiting film are obtained, and disappearance and reproduction of a light-controlled or temperature-controlled pattern realize multiple anti-counterfeiting functions of the film; however, the holographic processing technology is limited by cost and has insignificant economic benefit. For the existing multiple anti-counterfeiting technologies or products, such as CN 1600535B, CN 113788972A, CN 2127934U, and CN 113059942A, complex preparation processes are generally required or the existing multiple anti-counterfeiting technologies or products depend on instruments and equipment with higher manufacturing cost.

Disclosure of Invention

The invention aims to provide a preparation method and application of a double anti-counterfeiting polymer film. The invention provides a preparation method of a polymer film with double anti-counterfeiting functions, which is simple in process, low in cost and high in information encryption degree, based on fluorescence and liquid crystal anti-counterfeiting technologies.

The preparation method of the double anti-counterfeiting polymer film is to prepare a copolymerized polymer film after copolymerizing monomer molecules containing liquid crystal elements and monomer molecules containing styryl pyrene structures.

The mesogen contained in the monomer molecule containing the mesogen can form a main molecular structure of a liquid crystal ordered phase. Further, the temperature of the liquid crystal phase in the monomer molecule containing the mesogen is higher than room temperature.

Such as liquid crystal moiety-containing monomer molecules of the following structure:

wherein R is H or CH ₃ ；n=1-6。

The ordered structure only needs the aggregation of liquid crystal elements to form an ordered structure in any direction, namely a liquid crystal multi-domain oriented structure; and the liquid crystal elements are not required to be oriented into a single-domain structure, so that the subsequent film preparation process is simpler.

The structure of the monomer molecule containing the styryl pyrene structure before dimerization can generate fluorescence when being excited, and the structure after dimerization cannot be excited to generate fluorescence. The styrylpyrene motif as in some embodiments can fluoresce under excitation from a 320 to 430 nanometer LED lamp. For example, the structure of the monomer molecule containing styryl pyrene structure used in the examples of the present invention is as follows:

wherein R is H or CH ₃ ；n=1-6。

The polymerization reaction mode between the monomer molecules containing the liquid crystal elements and the monomer molecules containing the styryl pyrene structure can be free radical polymerization, anion polymerization or coordination polymerization, and is preferably a free radical polymerization mode. The radical polymerization method may be a conventional radical polymerization method or a living radical polymerization method, and a conventional radical polymerization method is preferably used.

In the polymerization process, the feeding mol ratio of monomer molecules containing liquid crystal elements to monomer molecules containing styryl pyrene structure is 10:1 to 1: 1.

The preparation of the copolymer polymer film can adopt a common film-forming method of a non-liquid crystal polymer, such as a dripping method and a spin coating method which are simple in process, and preferably adopts a dripping method.

In the above process, all drugs are of reagent purity.

In the above method, the polymer film is in an amorphous state after the preparation.

The polymer film is applied to preparing anti-counterfeiting materials.

The anti-counterfeiting material has a dual anti-counterfeiting function by writing anti-counterfeiting information twice by using visible light with the wavelength range of 400 to 470 nanometers.

Specifically, the method comprises the following steps:

writing the first layer of anti-counterfeiting information: writing a first layer of anti-counterfeiting information on the surface layer of the polymer film under the low-light-intensity and short-time illumination conditions of visible light of 400-470 nanometers with the assistance of a first mask plate.

The light intensity range of the low light intensity is 1 to 10 milliwatts per square centimeter, and the short time is 2 to 10 seconds.

Writing the second layer of anti-counterfeiting information: and under the conditions of high light intensity of visible light of 400-470 nanometers and long-time illumination, writing deep information in the first layer anti-counterfeiting information writing area on the surface layer by the aid of a second mask plate.

The light intensity range of the high light intensity is 50 to 200 milliwatts per square centimeter, and the long time is 50 to 500 seconds.

After the anti-counterfeiting information is written in twice, the polymer film material is annealed to obtain the double anti-counterfeiting film material.

Further, in the annealing process, the annealing temperature is higher than a certain range of the order-disorder transition temperature of the liquid crystal copolymer film, such as 50 to 150 ℃; and slowly cooling, such as below 10 deg.C per minute, to promote the formation of ordered structures of the mesogens.

After deep information is written in the dimerization process of the styryl pyrene structure, the newly formed dimerization structure prevents ordering of liquid crystal elements in the subsequent annealing process; the regions of the film where the deep information is written are not annealed to form an ordered structure and remain in an amorphous state.

The surface information is read by exciting fluorescence. In particular to a fluorescent signal which is obtained by irradiating 365 nm light with weak light intensity and reading the fluorescent signal. The illumination condition can only excite the structure of the styryl pyrene which is not dimerized on the surface layer to emit fluorescence, the structure after dimerization can not emit light, and the structure of the styryl pyrene which is not dimerized on the deep layer can not be excited to emit fluorescence, so that surface layer information is given according to the existence of fluorescence signals of different areas. No fluorescence signal is given for any region that dimerizes deep on top of the surface dimerization region, i.e. the deep signal is hidden in the surface signal. The light intensity range of the weak light intensity is 0.01 to 0.1 milliwatt/square centimeter, and the wavelength range of the LED lamp for reading information is 320 to 430 nanometers.

The deep information is obtained by reading the ordered signal of the mesogen using a polarization microscope or a polarizing plate. The surface dimerization is not enough to limit the orientation of the bottom liquid crystal element in the annealing process; therefore, only on the basis of surface layer dimerization, the film area subjected to deep dimerization can be in an amorphous state after annealing, namely the area is in a dark state under a polarizing microscope; the liquid crystal elements are oriented to generate an ordered structure in the region which is not deeply dimerized due to the annealing process, namely the region is in a bright state under a polarizing microscope; the bright and dark signals of the different areas give deep information.

Compared with the prior art, the invention has the following beneficial effects:

1. the technology introduces styryl pyrene structure and liquid crystal element into copolymer polymer, and prepares double anti-counterfeiting polymer film products by writing anti-counterfeiting information twice;

2. the raw materials used for preparing the copolymer are cheap chemicals, and have high yield, excellent quality and low energy consumption. The preparation process of the copolymer film material is the same as that of a common polymer film forming process, is relatively mature, simple and feasible, and has low cost;

3. in the aspect of information writing, the technology does not need expensive equipment, has simple writing mode and is easy for large-scale production;

4. the technical idea is novel and is the leading-edge field of basic research; and the anti-counterfeiting film has a very large practical application value in the future.

In conclusion, the product and the preparation method thereof have very high cost performance and feasibility.

Drawings

FIG. 1 is a scheme showing a reaction scheme for synthesizing a copolymer prepared in example 1.

FIG. 2 is a nuclear magnetic hydrogen spectrum characterization of the co-polymer prepared in example 1.

FIG. 3 is a gel permeation chromatographic characterization of the copolymeric polymer prepared in example 1. The ordinate in the figure represents intensity as a relative value.

FIG. 4 is a differential scanning calorimetry analysis of the co-polymer prepared in example 1 to characterize the temperature of the ordered disordered phase transition of the polymer. The ordinate in the graph is in W/g, and is a relative value.

FIG. 5 is a schematic diagram of dimerization reaction of styryl pyrene structure in a copolymerized polymer film.

FIG. 6 is a graph showing the change of fluorescence intensity with time of light of the copolymeric polymer film prepared in example 1.

FIG. 7 shows a polarization microscope characterization of the copolymeric polymeric film prepared in example 1.

Fig. 8 is a schematic diagram of double-layer information written in the copolymerized polymer film prepared in example 1 and implementation of a double-layer anti-counterfeiting structure, in which a surface layer realizes a first layer of anti-counterfeiting structure through the action of a photomask 1 and fluorescence excitation of styryl pyrene; in addition, the second layer of anti-counterfeiting information is realized through the action of the photomask plate 2 and the sequential conversion of the liquid crystal elements.

FIG. 9 is a nuclear magnetic hydrogen spectrum representation of the monomer molecule containing liquid crystal element in example 2.

FIG. 10 is the nuclear magnetic spectrum characterization of the monomer molecule containing styryl pyrene structure in example 2.

Detailed Description

The following description of the present patent is given by way of specific examples, but the present patent is not limited thereto.

The experimental methods used in the following examples are all conventional methods unless otherwise specified; reagents, materials and the like used in the following examples are commercially available unless otherwise specified.

Example 1: preparation of double anti-counterfeiting polymer film

1. Synthesis of monomer molecules containing liquid crystal elements

1) The synthesis of compound 1 in figure 1 is as follows: 16.5 g of 4-hydroxybenzoic acid was dissolved in a mixed solvent of 42 ml of ethanol and 18 ml of pure water, and slowly dropped into 50 ml of an ethanol solution containing 17.8 g of potassium hydroxide and 2.7 g of potassium iodide. 22.6 g of 6-chloro-1-hexanol was slowly added to the above solution, and after 24 hours of the reflux reaction, it was cooled to room temperature. The reaction mixture was washed with 100 ml of ether and acidified with hydrochloric acid to pH =4, at which time a large amount of precipitate formed; the precipitate was washed with 100 ml of pure water and repeated three times. Recrystallizing the product in a mixed solvent of 120 ml of ethanol and 30 ml of pure water to obtain 20.0 g of the product, wherein the yield is 69.9%;

2) The synthesis of compound 2 in figure 1 is as follows: dissolving 2.1 ml of methacryloyl chloride in 22 ml of nitrogen-nitrogen dimethyl acetamide, slowly dropping 17 ml of a solution dissolved with 4.0 g of compound 1 in an ice-water bath, reacting at room temperature for 36 hours, pouring a reaction solution into pure water, washing a generated precipitate with 100 ml of pure water, and repeating the steps for three times; vacuum drying overnight, and purifying with silica gel column using dichloromethane/ethyl acetate (volume ratio 5/1) eluent to obtain 3.8 g of compound 2, 73.8% yield;

3) The synthesis of compound 3 in FIG. 1, i.e. the monomer molecule containing mesogen, is as follows: 1.3 g of diisopropylcarbodiimide was added dropwise to a 50 ml dichloromethane solution containing 2.0 g of the compound 2,0.9 g of 4-cyanophenol and 0.1 g of 4-dimethylaminopyridine dissolved in an ice-water bath, and reacted at room temperature for 12 hours; after the reaction was completed, the solvent was removed under reduced pressure, and the mixture was purified by silica gel column using an eluent of petroleum ether/ethyl acetate (volume ratio 3/1) to obtain 1.5 g of compound 3, with a yield of 56.9%;

2. synthesis of monomer molecule containing styryl pyrene structure

1) The synthesis of compound 5 in figure 1 is as follows: 2.5 g of the compound 4- (E) -4- (2- (pyrene-1-yl) vinyl) phenol was added to 50 ml of nitrogen-dimethyl formamide having 1.28 g of 6-chloro-1-hexanol, 1.62 g of potassium carbonate and 0.13 g of potassium iodide dissolved therein, and the mixture was heated to 100 ℃ to react for 16 hours; after the reaction is finished, adding 100 ml of pure water and uniformly mixing; extraction with 100 ml dichloromethane was repeated three times; the organic phase is washed with 100 ml of saturated saline solution, repeated three times and dried by proper amount of magnesium sulfate; the extract was spin dried under vacuum and purified over silica gel column using dichloromethane/ethyl acetate (1/1 by volume) eluent and recrystallized in 100 ml dichloromethane to yield 1.7 g of compound 5 in 51.9% yield;

2) The synthesis of compound 6 in FIG. 1, i.e. the monomer molecule containing styryl pyrene structure, is as follows: 0.72 ml of methacryloyl chloride was dissolved in 100 ml of dichloromethane; slowly dripping into 5 ml of dichloromethane solution dissolved with 1.6 g of compound 5 under the condition of ice-water bath, reacting for 15 minutes at the temperature of 0 ℃, and reacting for 12 hours at room temperature; washing the reaction solution with 100 ml of saturated saline solution, washing with 100 ml of saturated sodium bicarbonate solution, drying with magnesium sulfate, distilling under reduced pressure to remove a dichloromethane solvent, and purifying a crude product with a silica gel column by using a pure dichloromethane eluent to obtain 1.6 g of a compound 6, wherein the yield is 86.8%;

3. synthesis of copolymer containing styryl pyrene structure and liquid crystal element

Using a closable reaction bottle, 1.2 g of compound 3 (monomer molecule containing liquid crystal element) and 0.36g of compound 6 (monomer molecule containing styryl pyrene structure), wherein the molar ratio of compound 3 to compound 6 is 5: dissolving the mixture in 2 ml of nitrogen-nitrogen dimethyl formamide, adding 3 mg of azobisisobutyronitrile as an initiator, blowing nitrogen to form an inert atmosphere, heating to 60 ℃, and reacting for 48 hours in a dark place; after the reaction is finished, precipitating in 40 ml of methanol to obtain flocculent copolymer; after drying, dissolving in 2 ml tetrahydrofuran, using self-prepared chromatographic column to completely remove unreacted compound 3 and compound 6, obtaining compound 7, namely 1.42 g of pure copolymerized polymer containing styryl pyrene structure and mesogen, with the yield of 91.0%; the nuclear magnetic hydrogen spectrum is characterized as shown in figure 2; gel permeation chromatography characterization as shown in fig. 3, copolymer 7 had a number average molecular weight of 143.3 kilograms per mole and a molecular weight distribution of 4.9;

4. preparation of copolymerized polymer film

Dissolving 0.005 g of the copolymer 7 in 1 ml of cyclopentanone, stirring with a magneton overnight, dripping the solution on a clean glass sheet in a fume hood, and naturally leveling; after the solvent is volatilized for 12 hours, the copolymer polymer film is dried in vacuum overnight at room temperature;

5. writing of anti-fake information (fig. 8)

1) Writing the first layer of anti-counterfeiting information: irradiating for 10 seconds by using an LED lamp with the light intensity of 10 milliwatts/square centimeter and the wavelength of 455 nanometers under the assistance of a photomask; at the moment, the styryl pyrenyl elements on the surface layer of the membrane in the area receiving illumination undergo dimerization reaction; according to the characteristics of styryl pyrene molecules, the styryl pyrene molecules can be excited by light with the wavelength of 365 nanometers to generate light blue fluorescence before dimerization, and after dimerization, the performance of light emission after excitation is lost due to the breakage of a conjugated structure, so that the first layer of anti-counterfeiting information is written in the surface layer of the film, and according to the fluorescence characteristics of styryl pyrene, the first layer of anti-counterfeiting information can be read by using LED lamps with the wavelengths of 320-430 nanometers. FIG. 6 is a graph showing the change in fluorescence intensity of a thin film after being irradiated with 10 mW/cm LED lamp with a 455 nm wavelength for various periods of time; as can be seen from fig. 6, after 10 seconds of irradiation, the fluorescence intensity of the film decreases by 15%, and it is often determined that the fluorescence decrease is mainly concentrated on the surface layer of the film, which is sufficient for forming a surface layer pattern; wherein, the pattern information written inside the letter area in fig. 8 is representative;

2) Writing the second layer of anti-counterfeiting information: in the anti-counterfeiting information area written in the first layer, namely the area in which styryl pyrene basic elements are dimerized passes through another designed photomask structure again, the dimerization reaction of styryl pyrene at a deeper layer is further caused, and the light condition of irradiating the 455-nanometer wavelength LED lamp with the wavelength of 100 milliwatts/square centimeter for 100 seconds is given, so that the dimerization reaction of styryl pyrene at the exposed area is sufficiently initiated. After the above two times of information writing, the whole copolymer film is still in an amorphous state. Then, the film is heated to 150 ℃ and then cooled at the speed of 5 ℃/min. After the annealing process, the regions which are not written for the second time form an ordered structure, including the regions which are written for the first time only (since the regions are not affected by surface dimerization, the ordered structure is also formed); in the area subjected to secondary writing, due to the cross-linking caused by styryl pyrene dimerization, the movement of the liquid crystal elements is limited or the ordering process of the liquid crystal elements is prevented by a dimeric structure, so that the area subjected to secondary writing of the film does not form an ordered structure through the annealing process, the anti-counterfeiting information of a deep layer (a second layer) is written on the basis of the surface layer of the film, and the representation of the order-disorder transition temperature of the copolymer is shown in fig. 4. Under a polarization microscope, regions with different brightness are formed according to the characteristics of ordered phase and disordered phase of the liquid crystal, so that the second layer of anti-counterfeiting information, namely the information of the two-dimensional code shown in fig. 8, is read. The dimerization process of styrylpyrene structure in the above information writing process is shown in FIG. 5. In addition, to further verify the feasibility of information writing, a photomask with holes is used, the film is irradiated by using a 455-nm wavelength LED lamp with the wavelength of 100 milliwatts/square centimeter for 100 seconds, then the temperature of the film is raised to 150 ℃, the temperature is reduced at the speed of 5 ℃/min, the liquid crystal phase is observed under a polarizing microscope, as shown in fig. 7, the hole area of the film is in an amorphous state, the non-cavity part is in the liquid crystal phase, and a pattern is further formed.

Example 2:

the molecular selection of the monomer containing the mesogen is as follows:

wherein the R substituent is H, n =6; nuclear magnetic characterization is shown in figure 9;

the molecular selection of the monomer containing the styryl pyrene structure is as follows:

wherein the R substituent is H, n =6; nuclear magnetic characterization is shown in fig. 10;

selecting the ratio of monomer molecules containing liquid crystal elements to monomer molecules containing styryl pyrene structure as 2:1, copolymerization method and film preparation the surface layer was written using an LED lamp of 455 nm wavelength of 10 mW/cm for 20 seconds, as in example 1; deep information was written using a 100 mw/cm 455 nm wavelength LED lamp for 200 seconds. And heating the film to 200 ℃, and then cooling the film at the speed of 5 ℃/min to realize the writing of the double-layer information.

Example 3:

the molecular selection of the monomer containing the mesogen is as follows:

wherein the R substituent is CH ₃ ，n=3；

wherein the R substituent is CH ₃ ，n=3；

Selecting monomer molecules containing liquid crystal elements and monomer molecules containing a styryl pyrene structure in a ratio of 5:1, the preparation of the copolymer and the film thereof was the same as in example 1. The annealing conditions and the information writing conditions of the thin film were the same as those of example 2.

Example 4:

the molecular selection of the monomer containing the mesogen is as follows:

wherein the R substituent is H, n =3;

wherein the R substituent is H, n =3;

selecting monomer molecules containing liquid crystal elements and monomer molecules containing a styryl pyrene structure in a ratio of 5:1, the preparation of the copolymer and the film thereof was the same as in example 1. This example first writes the deep information using a 455 nm wavelength LED lamp of 100 mw/cm for 200 seconds; the security film was then annealed using the same conditions as in example 1. Then, on the area where the deep information was written, the surface information was written using an LED lamp of 455 nm wavelength of 10 mw/cm for 10 seconds. The writing of the information for the second time not only hides the deep anti-counterfeiting information written for the first time, but also adds a new anti-counterfeiting layer.

Example 5:

the molecular selection of the monomer containing the mesogen is as follows:

wherein the R substituent is-CH ₃ ，n=6；

wherein the R substituent is-CH ₃ ，n=6；

Selecting the monomer molecules containing liquid crystal elements and the monomer molecules containing the styryl pyrene structure in a ratio of 20:1, the method for producing the copolymer and the film and the annealing conditions were the same as in example 1. This embodiment allows writing deep information for thicker films due to the reduced styryl pyrenyl content. The embodiment can be applied to the anti-counterfeiting film needing higher mechanical strength.

Claims

1. A preparation method of a dual anti-counterfeiting polymer film is characterized by comprising the following steps:

the copolymerized polymer film is prepared by copolymerizing monomer molecules containing liquid crystal elements and monomer molecules containing styryl pyrene structure;

the mesogen contained in the mesogen-containing monomer molecule can form a main molecular structure of a liquid crystal ordered phase, and the temperature of the liquid crystal phase in the mesogen-containing monomer molecule for carrying out order-disorder transition is higher than room temperature;

the structure of the monomer molecule containing the styryl pyrene structure before dimerization can generate fluorescence when excited, and the structure after dimerization cannot generate fluorescence when excited.

2. The method according to claim 1, wherein the mesogen-containing monomer molecule is selected from one of the following structures:

wherein R is H or CH ₃ ；n=1-6。

3. The method according to claim 1, wherein the monomer molecule containing a styryl pyrene structure is selected from one of the following structures:

wherein R is H or CH ₃ ；n=1-6。

4. The method of claim 1, wherein:

in the polymerization process, the feeding molar ratio of monomer molecules containing liquid crystal elements to monomer molecules containing styryl pyrene structure is 10:1 to 1: 1.

5. Use of a polymer film obtainable by the process according to any one of claims 1 to 4, characterized in that: and preparing the anti-counterfeiting material by using the copolymerized polymer film.

6. Use according to claim 5, characterized in that:

7. Use according to claim 6, characterized in that:

writing in the first layer of anti-counterfeiting information: writing a first layer of anti-counterfeiting information on the surface layer of the polymer film under the low-light-intensity and short-time illumination conditions of visible light of 400-470 nanometers with the assistance of a first mask plate;

writing the second layer of anti-counterfeiting information: and writing deep information in the first layer anti-counterfeiting information writing area on the surface layer under the high-light-intensity and long-time illumination conditions of visible light of 400-470 nanometers with the assistance of a second mask plate.

8. Use according to claim 7, characterized in that:

the light intensity range of the low light intensity is 1 to 10 milliwatts per square centimeter, and the short time is 2 to 10 seconds;

9. Use according to claim 6, characterized in that:

after the anti-counterfeiting information is written twice, the anti-counterfeiting material is annealed, and then the dual anti-counterfeiting film material can be obtained.

10. Use according to claim 9, characterized in that:

in the annealing process, the annealing temperature is higher than the temperature at which the order-disorder transition of the liquid crystal phase of the copolymer polymer film occurs.