Photosensitive fluorescent polyurethane material as well as preparation method and application thereof

Abstract

The invention discloses a photosensitive fluorescent polyurethane material as well as a preparation method and application thereof, and belongs to the technical field of preparation of optical anti-counterfeiting materials. The photosensitive fluorescent polyurethane material disclosed by the invention integrates double functions of photosensitive patterning and fluorescence, has wide environment adaptability, supports large-scale continuous preparation, can be used for efficiently manufacturing large-area holographic color patterns through a mask exposure technology, meets the anti-counterfeiting requirements of complex scenes, and has wide application prospects. The low-cost manufacturing process and the high-added-value anti-counterfeiting characteristic of the anti-counterfeiting packaging film remarkably reduce the production cost and improve the product competitiveness, and an innovative solution is provided for the packaging anti-counterfeiting field.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical anti-counterfeiting material preparation, and in particular relates to a photosensitive fluorescent polyurethane material and a preparation method and application thereof. Background Art

[0002] Current anti-counterfeiting materials are generally limited by the industry's dilemma of a single recognition mode that is easily counterfeited. Traditional fluorescent anti-counterfeiting relies on static luminescence characteristics, which can be easily deciphered through spectral analysis. While physical structural color anti-counterfeiting offers unique optical effects, it struggles to achieve dynamic response. Existing technologies that physically blend fluorescent and photosensitive components often suffer from performance degradation due to phase separation, and their functionality only achieves mechanical superposition, failing to generate synergistic effects.

[0003] In view of this, there is an urgent need in this field to develop a new anti-counterfeiting material that can break through functional barriers. Summary of the Invention

[0004] To address the problem that current anti-counterfeiting materials are generally limited to a single recognition mode and are easily counterfeited, the present invention provides a photosensitive fluorescent polyurethane material, its preparation method, and application. The present invention pioneers the use of molecular design to simultaneously incorporate photosensitive and fluorescent groups into the polyurethane backbone, constructing a dynamic multimodal anti-counterfeiting system. Triggered by ultraviolet light, this material simultaneously implements multiple anti-counterfeiting mechanisms: the photosensitive groups form a periodic grating on the surface through light induction, producing rainbow structural colors through Bragg diffraction; the fluorescent groups emit high-intensity, characteristic blue-cyan fluorescence under ultraviolet light. The key lies in the molecular-level synergistic effect of the two groups, which causes the fluorescence emission intensity and wavelength to evolve in real time with ultraviolet light conditions, forming a unique dynamic optical anti-counterfeiting mode.

[0005] A photosensitive fluorescent polyurethane material with the chemical structure formula:

[0006] ;

[0007] Among them, structural unit A is an alkyl or aryl structure containing at least two isocyanate groups; structural unit B is an aryl structure containing at least two hydroxyl or amino groups, which is connected to the photosensitive group through an alkane chain with an ether bond; structural unit C is an alkyl or aryl structure containing at least two hydroxyl groups;

[0008] Wherein, x∶(y+z) is 1∶(1-99);

[0009] The photosensitive fluorescent polyurethane material described herein is formed by copolymerization of a photosensitive monomer, a fluorescent monomer, and a polymer. The photosensitive groups introduced into the material impart excellent light-responsive properties to the polyurethane. Under ultraviolet light, the material's surface undergoes a photoreaction, forming a grating structure. This structure produces a significant structural color under white light through the Bragg diffraction effect, resulting in a rainbow pattern. Furthermore, the fluorescent groups introduced into the photosensitive fluorescent polyurethane material emit strong blue-cyan fluorescence under ultraviolet light excitation. A synergistic effect exists between the photosensitive and fluorescent groups, causing the fluorescent groups' emission behavior (including emission intensity and wavelength) to vary with ultraviolet light exposure conditions.

[0010] A method for preparing the above-mentioned photosensitive fluorescent polyurethane material comprises the following steps: under the protection of an inert gas, adding a diisocyanate monomer having structural unit A and a photosensitive diamine or diol monomer having structural unit B to an organic solvent, and stirring the mixture in an ice-water bath at 0-5°C for reaction (first reaction); then, sequentially adding a diamine or diol monomer having structural unit C, a tetraphenylethylene monomer containing two amino groups (i.e., a fluorescent group monomer), and a catalyst, and continuing the stirring reaction (second reaction) to obtain a photosensitive fluorescent polyurethane solution; coating the photosensitive fluorescent polyurethane solution on a substrate, then transferring the solution to a vacuum oven and drying it at 50-100°C for 30-120 minutes to obtain the photosensitive fluorescent polyurethane material. The amount of the photosensitive diamine or diol monomer having structural unit B is 1-50% of the total amount of all monomers; the amount of the tetraphenylethylene monomer containing two amino groups is 1-10% of the total amount of all monomers.

[0011] Furthermore, the time of the first reaction is 2 hours; and / or the conditions of the second reaction are: reacting at room temperature for 7 hours, heating to 40° C. for reaction for 12 hours, and further heating to 60° C. for reaction for 3 hours.

[0012] Furthermore, the added amount of the catalyst is 0.1-5% of the total mass of the monomer raw materials of the photosensitive fluorescent polyurethane material.

[0013] Furthermore, the organic solvent is selected from dichloromethane, dimethyl sulfoxide, sulfolane, N,N-dimethylformamide, N,N-dimethylacetamide or N-methylpyrrolidone, or a mixture of two or more of the above solvents in any proportion.

[0014] An application of the above-mentioned photosensitive fluorescent polyurethane material in the preparation of a stimulus-responsive anti-counterfeiting label with dual optical effect characteristics.

[0015] The present invention also provides a method for preparing a stimulus-responsive anti-counterfeiting label with dual optical effect characteristics, comprising the following steps: using a photosensitive fluorescent polyurethane solution to prepare a self-supporting dry film or a substrate-supported dry film of the photosensitive fluorescent polyurethane material; then fixing the self-supporting dry film or the substrate-supported dry film under a UV-transmissive mask plate, exposing the self-supporting dry film or the substrate-supported dry film with ultraviolet light through the UV-transmissive mask plate, and after the exposure is completed, developing the self-supporting dry film or the substrate-supported dry film, that is, soaking it in an organic solvent and then blowing it dry, and preparing a holographic color pattern on the surface of the self-supporting dry film or the substrate-supported dry film to obtain the stimulus-responsive anti-counterfeiting label with dual optical effect characteristics.

[0016] During the above preparation process, ultraviolet light irradiation triggers the photosensitive groups to undergo a photochemical reaction, forming a grating concave-convex structure with a period of 0.1-10μm and a height of 30-1000nm on the surface of the self-supporting dry film or the substrate-supported dry film. This structure produces an angle-dependent rainbow pattern through the Bragg diffraction effect. The grating period is directly controlled by the mask pattern parameters, and the structure height is controlled in coordination with the exposure time and exposure amount.

[0017] The structural formula of the photosensitive group in the photosensitive fluorescent polyurethane material after irradiation with ultraviolet light is as follows:

[0018] ;

[0019] Further, the photosensitive fluorescent polyurethane solution is coated on the surface of the substrate by a casting method or a spin coating method to form a wet film with a thickness of 5-500 μm, and then heated on a hot plate, dried with air or vacuum dried to remove the solvent to form a dry film;

[0020] Furthermore, the ultraviolet-transmissive mask plate has a grating structure, the exposure line width of the grating structure is 0.1-10 μm, and the grating period is 0.1-10 μm.

[0021] Furthermore, the wavelength of the ultraviolet light is 100-400 nm.

[0022] Furthermore, the exposure time is 10-60s, and the exposure dose is 50-250mJ / cm 2 .

[0023] Furthermore, the organic solvent is selected from methanol, ethanol, propanol, acetonitrile, acetone or petroleum ether, or a mixture of two or more of the above organic solvents in any proportion.

[0024] A stimulus-responsive anti-counterfeiting label with dual optical effect characteristics prepared by the above preparation method.

[0025] Compared with the prior art, the present invention has the following advantages and technical effects:

[0026] The photosensitive fluorescent polyurethane material disclosed in the present invention integrates the dual functions of photosensitivity patterning and fluorescence, has wide environmental adaptability, supports large-scale continuous preparation, and can efficiently produce large-area holographic color patterns through mask exposure technology, meeting the anti-counterfeiting needs of complex scenarios. Its low-cost manufacturing process and high-value-added anti-counterfeiting properties significantly reduce production costs and improve product competitiveness, providing innovative solutions for the field of packaging anti-counterfeiting.

[0027] The invention discloses a stimulus-responsive anti-counterfeiting label with dual optical effect characteristics, which can be formed into a highly stable transparent film adaptable to different environments through molecular structure design. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 A chemical reaction formula for a method for synthesizing a photosensitive fluorescent polyurethane material provided in Example 1;

[0030] Figure 2 The pattern of the UV-transmissive mask in Example 1;

[0031] Figure 3 This is an atomic force microscope image of the concave-convex structure of the microscopic optical grating in the stimulus-responsive anti-counterfeiting label with dual optical effect characteristics prepared in Example 1;

[0032] Figure 4 This is a data diagram of the period and height of the microscopic grating concave-convex structure in the stimulus-responsive anti-counterfeiting label with dual optical effect characteristics prepared in Example 1;

[0033] Figure 5 This is a trend diagram of the fluorescence emission spectrum of the stimulus-responsive anti-counterfeiting label with dual optical effects prepared in Example 1 under continuous ultraviolet light irradiation;

[0034] Figure 6 A digital photo of the stimulus-responsive anti-counterfeiting label with dual optical effects prepared in Example 1 under white light;

[0035] Figure 7 A digital photograph of the stimulus-responsive anti-counterfeiting label with dual optical effects prepared in Example 1 under ultraviolet light (365 nm);

[0036] Figure 8A chemical reaction formula for a method for synthesizing a photosensitive fluorescent polyurethane material provided in Example 2;

[0037] Figure 9 The pattern of the UV-transmissive mask in Example 2;

[0038] Figure 10 This is an atomic force microscope image of the concave-convex structure of the microscopic optical grating in the stimulus-responsive anti-counterfeiting label with dual optical effect characteristics prepared in Example 2;

[0039] Figure 11 This is a data diagram of the period and height of the microscopic grating concave-convex structure in the stimulus-responsive anti-counterfeiting label with dual optical effect characteristics prepared in Example 2;

[0040] Figure 12 This is a trend diagram of the fluorescence emission spectrum of the stimulus-responsive anti-counterfeiting label with dual optical effects prepared in Example 2 under continuous ultraviolet light irradiation;

[0041] Figure 13 A digital photo of the stimulus-responsive anti-counterfeiting label with dual optical effects prepared in Example 2 under white light;

[0042] Figure 14 This is a digital photo of the stimulus-responsive anti-counterfeiting label with dual optical effects prepared in Example 2 under ultraviolet light (365 nm). DETAILED DESCRIPTION

[0043] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0044] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0045] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0046] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the present invention. The present description and examples are intended to be illustrative only.

[0047] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0048] The room temperature in the present invention refers to 25±2°C.

[0049] Example 1

[0050] The chemical reaction formula of a photosensitive fluorescent polyurethane material synthesis method provided in this embodiment is as follows: Figure 1 shown.

[0051] The specific preparation method of the photosensitive fluorescent polyurethane material is as follows:

[0052] 22.18 kg (327 mol) of photosensitive group-containing benzyl diamine (as shown in the above formula) and 46.68 kg (209.96 mol) of isophorone diisocyanate (as shown in the above formula) were added to a reactor containing 189.60 kg of N,N-dimethylformamide (DMF) under anhydrous and inert gas (nitrogen, the same below) protection conditions, and stirred in an ice-water bath at 0-5°C for 2 hours. Then, 21.03 kg (177.96 mol) of 1,6-hexanediol (as shown in the above formula), 0.73 kg (2.014 mol) of 4-(2-(4-aminophenyl)-1,2-diphenylvinyl)aniline, and 0.08 kg of catalyst dibutyltin dilaurate were added to the equipment in sequence. After stirring and reacting at room temperature for 7 hours, the reaction was moved into an oil bath and heated to 40°C for 12 hours, and then continued to heat to 60°C for 3 hours. The reaction was carried out for 24 hours, and a photosensitive fluorescent polyurethane solution (wherein x:(y+z) was 1:9) was prepared by a segmented heating method. The obtained photosensitive fluorescent polyurethane solution was defoamed at room temperature in the dark, and then the photosensitive fluorescent polyurethane solution was spin-coated on a cover glass treated with dual-wavelength ultraviolet light of 185 nm and 254 nm for 15 minutes. The obtained photosensitive fluorescent polyurethane film was then transferred to a vacuum oven and baked at 100°C for 90 minutes to obtain a photosensitive fluorescent polyurethane dry film, i.e., a photosensitive fluorescent polyurethane material.

[0053] A stimulus-responsive anti-counterfeiting label with dual optical effects is prepared on the obtained photosensitive fluorescent polyurethane dry film. The specific preparation method is as follows:

[0054] The obtained photosensitive fluorescent polyurethane dry film was placed close to the chrome surface of a UV-transparent mask plate and fixed below the pattern of the UV-transparent mask plate (the UV-transparent mask plate has a grating structure with an exposure line width of 3 μm and a grating period of 6 μm). The film was then placed under a UV light source with a wavelength of 365 nm for selective exposure (exposure time of 10 s and exposure dose of 50 mJ / cm 2 ), after the exposure is completed, the photosensitive fluorescent polyurethane dry film is developed, that is, it is immersed in acetonitrile for 1 second and then blown dry, so as to obtain a holographic color pattern on the surface of the photosensitive fluorescent polyurethane dry film, and a stimulus-responsive anti-counterfeiting label with dual optical effect characteristics is prepared, wherein the pattern of the ultraviolet light-transmitting mask plate is as follows Figure 2 shown.

[0055] Figure 3 This is an atomic force microscope image of the concave-convex structure of the microscopic optical grating in the stimulus-responsive anti-counterfeiting label with dual optical effect characteristics prepared in Example 1. Figure 4 This is a graph showing the period and height of the microscopic grating concave-convex structure in the stimulus-responsive anti-counterfeiting label with dual optical effects prepared in Example 1. Figure 3 and Figure 4 It can be seen that the period of the grating concave-convex structure is 6μm and the average height is 30nm. Under this structure, white light irradiation causes a Bragg diffraction effect, producing an obvious rainbow pattern, and the pattern color has a strong angle dependence.

[0056] The stimulus-responsive anti-counterfeiting label with dual optical effect characteristics prepared in Example 1 was continuously irradiated with ultraviolet light to investigate the dynamic fluorescence response characteristics of the anti-counterfeiting label. The specific operation was as follows: 365nm ultraviolet light was used as the excitation light source to continuously irradiate the sample and systematically monitor the changes in the emission spectrum within the wavelength range of 400-600nm to show the evolution of the emission peak intensity and peak position in the 400-600nm range under different irradiation times.

[0057] Figure 5 This is a trend diagram of the fluorescence emission spectrum of the stimulus-responsive anti-counterfeiting label with dual optical effect characteristics prepared in Example 1 under continuous ultraviolet light irradiation, as shown in FIG. Figure 5 As shown, the stimulus-responsive anti-counterfeiting label with dual optical effects prepared in this example exhibits a strong blue-cyan fluorescence emission peak at 470nm, and the intensity and wavelength of this peak show regular changes with increasing UV irradiation time. This phenomenon is due to the photochemical transformation of the 1,4-dihydropyridine structure in the photosensitive group, that is, it gradually transforms into a 2,6-lutidine structure under UV excitation. This molecular reconstruction process changes the fluorescent group's absorption behavior of UV light, resulting in the coordinated evolution of the emission peak intensity and wavelength with irradiation time.

[0058] Under white light, the color development characteristics of the stimuli-responsive dual-optical anti-counterfeiting label prepared in Example 1 were observed. The experiment used a fixed camera position, with the sample placed on an adjustable tilt platform. By varying the platform's tilt angle (ranging from 5.1° to 10.8°), seven different color development states were captured.

[0059] Figure 6 This is a digital photo of the stimulus-responsive anti-counterfeiting label with dual optical effect characteristics prepared in Example 1 under white light; Figure 6 It can be seen that the stimulus-responsive anti-counterfeiting label with dual optical effect characteristics prepared in Example 1 exhibits a significant viewing angle-dependent rainbow effect under white light irradiation, and its color characteristics change with the observation angle;

[0060] Figure 7 This is a digital photo of the stimulus-responsive anti-counterfeiting label with dual optical effects prepared in Example 1 under ultraviolet light (365nm). Figure 7 It can be seen that under 365nm ultraviolet light excitation, the sample exhibits high-intensity blue-cyan fluorescence emission, and the intensity and wavelength of the fluorescence emission peak change regularly with the extension of ultraviolet irradiation time.

[0061] Example 2

[0062] The chemical reaction formula of a photosensitive fluorescent polyurethane material synthesis method provided in this embodiment is as follows: Figure 8 shown.

[0063] The specific preparation method of the photosensitive fluorescent polyurethane material is as follows:

[0064] 22.18 kg (327 mol) of benzyl diamine containing a photosensitive group (as shown in the above formula) and 36.57 kg (209.98 mol) of toluene diisocyanate (as shown in the above formula) were added to a reactor containing 189.60 kg of N, N-dimethylformamide under anhydrous and inert gas protection conditions, and stirred in an ice-water bath at 0-5 ° C for 2 h. Then, 21.03 kg (177.96 mol) of 1,6-hexanediol (as shown in the above formula), 0.73 kg (2.014 mol) of 4-(2-(4-aminophenyl)-1,2-diphenylvinyl) aniline, and 0.08 kg of catalyst dibutyltin dilaurate were added to the reactor in sequence. After stirring and reacting at room temperature for 7 h, the reaction was moved into an oil bath, heated to 40 ° C for 12 h, and then heated to 60 ° C for 3 h. After 24 hours, a photosensitive fluorescent polyurethane solution (wherein x:(y+z) is 1:9) is prepared by a segmented heating method. The obtained photosensitive fluorescent polyurethane solution is defoamed at room temperature in the dark, and the photosensitive fluorescent polyurethane solution is coated on a cover glass treated with dual-wavelength ultraviolet light of 185 nm and 254 nm for 15 minutes by spin coating. The obtained photosensitive fluorescent polyurethane film is then transferred to a vacuum oven and baked at 100°C for 90 minutes to obtain a photosensitive fluorescent polyurethane dry film, i.e., a photosensitive fluorescent polyurethane material.

[0065] A stimulus-responsive anti-counterfeiting label with dual optical effects is prepared on the obtained photosensitive fluorescent polyurethane dry film. The specific preparation method is as follows:

[0066] The obtained photosensitive fluorescent polyurethane dry film was placed close to the chrome surface of a UV-transparent mask plate and fixed below the pattern of the UV-transparent mask plate (the UV-transparent mask plate has a grating structure with an exposure line width of 2 μm and a grating period of 4 μm). The film was then placed under a UV light source with a wavelength of 365 nm for selective exposure (exposure time of 10 s and exposure dose of 50 mJ / cm 2 ), after the exposure is completed, the photosensitive fluorescent polyurethane dry film is developed, that is, it is immersed in acetonitrile for 1 second and then blown dry, so as to obtain a holographic color pattern on the surface of the photosensitive fluorescent polyurethane dry film, and a stimulus-responsive anti-counterfeiting label with dual optical effect characteristics is prepared, wherein the pattern of the ultraviolet light-transmitting mask plate is as follows Figure 9 shown.

[0067] Figure 10 This is an atomic force microscope image of the concave-convex structure of the microscopic optical grating in the stimulus-responsive anti-counterfeiting label with dual optical effect characteristics prepared in Example 2. Figure 11 This is a graph showing the period and height of the microscopic grating concave-convex structure in the stimulus-responsive anti-counterfeiting label with dual optical effects prepared in Example 2. Figure 10 and Figure 11It can be seen that the period of the grating concave-convex structure is 4μm and the average height is 190nm.

[0068] The stimulus-responsive anti-counterfeiting label with dual optical effects prepared in Example 2 was continuously irradiated with ultraviolet light to examine the dynamic fluorescence response characteristics of the stimulus-responsive anti-counterfeiting label with dual optical effects. Figure 12 This is a trend diagram of the fluorescence emission spectrum of the stimulus-responsive anti-counterfeiting label with dual optical effect characteristics prepared in Example 2 under continuous ultraviolet light irradiation, as shown in FIG. Figure 12 As shown in the figure, the stimulus-responsive anti-counterfeiting label with dual optical effects prepared in this example exhibits a strong blue-cyan fluorescence emission peak at 470nm, and the intensity and wavelength of this peak show regular changes with increasing UV irradiation time. This phenomenon is due to the photochemical transformation of the 1,4-dihydropyridine structure in the photosensitive group, that is, it gradually transforms into a 2,6-lutidine structure under UV excitation. This molecular reconstruction process changes the fluorescent group's absorption behavior of UV light, resulting in the coordinated evolution of the emission peak intensity and wavelength with irradiation time.

[0069] Figure 13 This is a digital photo of the stimulus-responsive anti-counterfeiting label with dual optical effect characteristics prepared in Example 2 under white light; Figure 13 It can be seen that the stimulus-responsive anti-counterfeiting label with dual optical effect characteristics prepared in Example 2 exhibits a significant viewing angle-dependent rainbow effect under white light irradiation, and its color characteristics change with the observation angle.

[0070] Figure 14 This is a digital photo of the stimulus-responsive anti-counterfeiting label with dual optical effects prepared in Example 2 under ultraviolet light (365nm). Figure 14 It can be seen that under 365nm ultraviolet light excitation, the sample exhibits high-intensity blue-cyan fluorescence emission, and the intensity and wavelength of the fluorescence emission peak change regularly with the extension of ultraviolet irradiation time.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A photosensitive fluorescent polyurethane material, characterized in that: The chemical structural formula is: ； Wherein, structural unit A is an alkyl or aryl structure containing at least two isocyanate groups; structural unit B is an aryl structure containing at least two hydroxyl or amino groups; structural unit C is an alkyl or aryl structure containing at least two hydroxyl groups; Among them, x:(y+z) is 1:(1-99).

2. A method for preparing the photosensitive fluorescent polyurethane material according to claim 1, characterized in that: The following steps are involved: Under the protection of an inert gas, a diisocyanate monomer having structural unit A and a photosensitive diamine or diol monomer having structural unit B are added to an organic solvent and stirred in an ice-water bath for a first reaction; then, a diamine or diol monomer having structural unit C, a tetraphenylethylene monomer containing two amino groups, and a catalyst are added in sequence, and stirring is continued for a second reaction to obtain a photosensitive fluorescent polyurethane solution; the photosensitive fluorescent polyurethane solution is coated on a substrate and vacuum-dried to prepare the photosensitive fluorescent polyurethane material.

3. The preparation method according to claim 2, characterized in that The added amount of the catalyst is 0.1-5% of the total mass of the monomer raw materials of the photosensitive fluorescent polyurethane material.

4. The preparation method according to claim 2, characterized in that The time of the first reaction is 2 hours; and / or, the conditions of the second reaction are: reacting at room temperature for 7 hours, heating to 40° C. for 12 hours, and further heating to 60° C. for 3 hours.

5. Use of the photosensitive fluorescent polyurethane material according to claim 1 in preparing a stimulus-responsive anti-counterfeiting label having dual optical effect characteristics.

6. A method for preparing a stimulus-responsive anti-counterfeiting label with dual optical effects, characterized in that: The following steps are involved: Prepare a self-supporting dry film or a substrate-supported dry film of the photosensitive fluorescent polyurethane material according to claim 1; The self-supporting dry film or the substrate-supported dry film is exposed to ultraviolet light through a UV-transmissive mask. After the exposure is completed, the self-supporting dry film or the substrate-supported dry film is developed to prepare a holographic color pattern on the surface of the self-supporting dry film or the substrate-supported dry film, thereby obtaining the stimulus-responsive anti-counterfeiting label with dual optical effect characteristics.

7. The preparation method according to claim 6, characterized in that The ultraviolet-transmissive mask plate has a grating structure, the exposure line width of the grating structure is 0.1-10 μm, and the grating period is 0.1-10 μm.

8. The preparation method according to claim 6, characterized in that The wavelength of the ultraviolet light is 100-400nm.

9. The preparation method according to claim 6, characterized in that The exposure time is 10-60s, and the exposure dose is 50-250mJ / cm 2 .

10. A stimulus-responsive anti-counterfeiting label having dual optical effects, prepared by the preparation method according to any one of claims 6 to 9.

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