Mechanochromic film with low angle dependence and fatigue resistance and preparation method and application thereof

Abstract

The application provides a force-induced color change film with low angle dependence and fatigue resistance and a preparation method and application thereof, and the force-induced color change film is prepared by the following steps: preparing a silica amorphous photonic crystal film through a sol-gel method, KH570 modification and a pulling method; and uniformly coating PDMS solution on both sides of the film to obtain the force-induced color change film with low angle dependence and fatigue resistance. The nano-silica photonic crystal has uniform particle size and good dispersibility in ethanol, so that the periodic and regular arranged amorphous photonic crystal film can be prepared through the pulling method, and the film has low angle dependence when observed at different angles under indoor diffuse light; through modification, carbon-carbon double bonds are grafted on the surface of the silica nanoparticles, the carbon-carbon double bonds react with hydroxyl groups and mercapto groups on the surface of PDMS, chemical bonds are introduced, the interface interaction between the inorganic silica nanoparticles and the PDMS is enhanced, and therefore the mechanical properties and fatigue resistance of the material are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of force-induced color change film, in particular to a force-induced color change film with low angle dependence and fatigue resistance, and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of information technology, information security plays an increasingly important role. How to prevent counterfeiters from using modern technology to counterfeit information, achieve reliable information security, and reduce economic losses caused by counterfeit and inferior products is a great challenge. Force-induced color change materials are a class of materials that can reversibly change the optical properties of substances after being stimulated by external mechanical force, and can visually detect and survey external force, so they are widely used in anti-counterfeiting, information encryption and other fields. Currently, force-induced color change materials are mainly prepared by physical structure regulation (such as photolithography technology, photonic crystal self-assembly), chemical synthesis (designing compounds containing specific force-induced color change group structures), and composite material preparation (compounding force-induced color change materials with other materials to enhance the color change effect).

[0003] The patent with publication number CN117924970A discloses a low-angle-dependent photonic crystal structural color material and a preparation method thereof. Photonic crystal structural color film is prepared by gravity sedimentation method, and finally the photonic crystal structural color film is ground, dispersed, ultrasonically treated and dried colloidal particles self-assembled by re-dispersion method to prepare a low-angle-dependent photonic crystal structural color material. The disadvantage of the present application is that the preparation process is complicated, time-consuming, and requires two film-forming conditions before and after, and the mechanical properties of the prepared film are not high, which cannot be applied to force-induced color change functional materials.

[0004] The patent with publication number CN115480324A discloses a preparation method of intelligent photonic crystal fabric with stretch color change function. Photonic crystal film is prepared by gravity sedimentation of photonic crystal silica nanometer microsphere suspension, then polydimethylsiloxane solution is coated on the photonic crystal film, and the stretch color change intelligent photonic crystal film is obtained by heating and curing. Then PDMS (polydimethylsiloxane) solution is coated on the black textile fabric, and the stretch color change intelligent photonic crystal film is placed on it, and the intelligent photonic crystal textile fabric with stretch color change function is prepared by heating and curing. The disadvantage of the present application is that the interfacial force between the stretch color change intelligent photonic crystal film and the fabric is low, and the two can be easily peeled off during stretching. Moreover, the color change effect of the composite fabric material is not uniform during repeated stretching, which cannot realize accurate monitoring of external force.

[0005] The patent with the publication number CN118112831A discloses an information presentation method and application based on force-induced color-changing cholesteric liquid crystal elastomer, which designs image information as multiple parts with different colors, uses force-induced color-changing cholesteric liquid crystal elastomer as a display, and presents different reading results under different observation conditions, thereby realizing multi-level encryption of image information.

[0006] Therefore, it is necessary to design an improved force-induced color-changing film with low angle dependence and fatigue resistance, and a preparation method and application thereof, so as to solve the above problems. SUMMARY

[0007] In view of the defects of the prior art, the purpose of the present application is to provide a force-induced color-changing film with low angle dependence and fatigue resistance, and a preparation method and application thereof, which modifies silica photonic crystals, prepares amorphous photonic crystal films by the pulling method, and prepares a force-induced color-changing film with low angle dependence, high mechanical strength and wear resistance, good thermal stability and chemical stability by compounding with polydimethylsiloxane.

[0008] To achieve the above purpose, the present application provides a preparation method of a force-induced color-changing film with low angle dependence and fatigue resistance, comprising the following steps:

[0009] S1. preparing nano-silica by the sol-gel method, modifying it with silane coupling agent KH570 to obtain modified nano-silica;

[0010] S2. configuring a modified nano-silica solution with a predetermined mass concentration, and preparing a silica amorphous photonic crystal film by the pulling method at a constant temperature;

[0011] S3. mixing polydimethylsiloxane prepolymer and curing agent uniformly for defoaming to obtain a PDMS solution, uniformly coating the two sides of the silica amorphous photonic crystal film obtained in step S2 with the PDMS solution, and performing heat curing and demolding treatment to obtain a force-induced color-changing film with low angle dependence and fatigue resistance.

[0012] As a further improvement of the present application, in step S1, the particle size of the nano-silica is 190-330 nm.

[0013] As a further improvement of the present application, in step S2, the concentration of the modified nano-silica solution is 3-7 wt%; and the thickness of the silica amorphous photonic crystal film is 1.0-1.2 mm.

[0014] Further, the constant temperature is 28-32 DEG C.

[0015] The pulling number of the pulling method is 15-25, the pulling speed is 0.8-1.5 mm / s, and the staying time during pulling is 55-65 seconds.

[0016] As a further improvement of the application, in step S3, the mass ratio of the polydimethylsiloxane prepolymer and the curing agent is 10:1.

[0017] Further, the temperature of the heat curing is 75-85 DEG C, and the time is 1.5-2 h.

[0018] Further, the thickness of the low-angle-dependent and fatigue-resistant force-induced color-changing film is 2.0-3.2 mm.

[0019] The application further provides a low-angle-dependent and fatigue-resistant force-induced color-changing film prepared by the above preparation method.

[0020] The above low-angle-dependent and fatigue-resistant force-induced color-changing film is used in the field of information encryption.

[0021] The application has the following beneficial effects:

[0022] 1. The application provides a low-angle-dependent and fatigue-resistant force-induced color-changing film and a preparation method and application thereof. Nano-silica is prepared by a sol-gel method, modified by a silane coupling agent KH570 to obtain modified nano-silica, and a silica amorphous photonic crystal film is prepared by a pulling method. Polydimethylsiloxane prepolymer and a curing agent are mixed uniformly and degassed to obtain a PDMS solution, which is uniformly coated on both sides of the silica amorphous photonic crystal film, and then heat curing and demolding are performed to obtain a low-angle-dependent and fatigue-resistant force-induced color-changing film. The application uses the sol-gel method to prepare nano-silica photonic crystals with different particle sizes. Since the particle sizes are uniform, the dispersibility in ethanol is good, and therefore, a periodic and regular amorphous photonic crystal film can be prepared at a uniform pulling speed under a certain temperature, with a hydrophilic glass slide as a base material, so that the film has low-angle dependence when observed at different angles under indoor diffuse light.

[0023] 2. The silica is modified by the silane coupling agent KH570 to graft a carbon-carbon double bond on the surface of the silica nanoparticles, so that the carbon-carbon double bond reacts with the hydroxyl and mercapto groups on the surface of the PDMS to introduce chemical bonds, and the interface interaction between the inorganic silica nanoparticles and the PDMS is enhanced, thereby improving the mechanical properties and fatigue resistance of the material, and the periodic structure of the silica can be deformed and recovered synchronously with the PDMS matrix, so that the color and information of the material can be reversibly changed. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 Schematic diagram of PDMS / modified SiO2 / PDMS "sandwich" film structure prepared by the present application.

[0025] Figure 2 Schematic diagram for preparing nano-silica.

[0026] Figure 3 Schematic diagram for modification principle of nano-silica.

[0027] Figure 4 Scanning electron microscope images of nano-silica particles with different particle sizes prepared in Examples 1-3 of the present application.

[0028] Figure 5 Particle size distribution diagrams of nano-silica particles with different particle sizes prepared in Examples 1-3 of the present application.

[0029] Figure 6 Related characterization diagrams of nano-silica microspheres prepared in Example 1 of the present application.

[0030] Figure 7 Digital photos of silica amorphous photonic crystal films prepared in Examples 1-3 of the present application under different angles of diffuse light.

[0031] Figure 8 Stress-strain curves of mechano-chromic films prepared in Example 1 and Comparative Examples 1-2 of the present application.

[0032] Figure 9 Cyclic tensile curves of mechano-chromic films prepared in Example 1 and Comparative Examples 1-2 of the present application.

[0033] Figure 10 Information "display" and "erasing" effect diagrams of mechano-chromic films prepared in Example 1 of the present application under different strains. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be described in detail below in combination with the drawings and specific examples.

[0035] Here, it also needs to be explained that, in order to avoid the present application being obscured by unnecessary details, only structures and / or processing steps closely related to the scheme of the present application are shown in the drawings, and other details not closely related to the present application are omitted.

[0036] In addition, it should be noted that the term "comprising" or any other variation thereof is intended to cover the non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not only include those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0037] The present application provides a preparation method of a low-angle-dependent and fatigue-resistant mechanochromic film, as shown in the formula: Figure 1 The preparation method comprises the following steps:

[0038] S1. Nanosilica is prepared by a sol-gel method, and is modified by using silane coupling agent KH570 to obtain modified nanosilica.

[0039] Specifically, nanosilica with a particle size of 190-330 nm is prepared by a sol-gel method. As shown in the formula: Figure 2 A reaction A liquid is prepared: an ammonia solution with a concentration of 7-9% is prepared, and is mixed with anhydrous ethanol at a volume ratio of 1:2, and is stirred in a water bath at 25-35°C for 10-15 min. A reaction B liquid is prepared: anhydrous ethanol containing 16-20% tetraethoxysilane is prepared at room temperature, and is magnetically stirred for 10-15 min. The reaction B liquid is quickly poured into the reaction A liquid, and the volume ratio of the reaction A liquid to the reaction B liquid is (1-2):1; the reaction is stirred for 4.5-5.5 h. After the reaction is completed, the product is centrifuged, washed, dried, and ground to obtain nanosilica powder. Nanosilica with different particle sizes can be prepared by adjusting the amount of ammonia.

[0040] The nanosilica is modified by using silane coupling agent KH570. A reaction A liquid is prepared: ethanol and deionized water are mixed at a volume ratio of 1:1 to prepare an ethanol solution, and the dried nanosilica is uniformly mixed with the ethanol solution at a solid-liquid ratio of 1 g:20 mL by ultrasonic mixing. A reaction B liquid is prepared: ethanol and deionized water are mixed at a volume ratio of 18:2 to obtain an alcohol-water medium, and the pH value of the solution is adjusted to 4.5-5.5 by using oxalic acid, and 5% KH570 by volume is added, and stirred at room temperature for 1-1.5 h. The reaction A liquid is added to the reaction B liquid, and the temperature is increased to 65-75°C, and the reaction is carried out at this temperature for 5-7 h. After cooling to room temperature, centrifugation, washing, and drying, the modified nanosilica powder is obtained by fully grinding.

[0041] As shown in the formula: Figure 3 The modification principle of the nanosilica is that the carbon-carbon double bond is grafted on the surface of the silica nanoparticles, reacts with the hydroxyl and mercapto groups on the surface of the PDMS, introduces chemical bonds, and enhances the interfacial force between the silica and the polydimethylsiloxane. Meanwhile, the periodic structure of the silica nanoparticles can be better reset after repeated deformation, so as to have better color change and stronger fatigue resistance.

[0042] S2. A modified nano-silica solution with a predetermined concentration is prepared, and a silica amorphous photonic crystal film is prepared by a pulling method at a constant temperature.

[0043] Specifically, the concentration of the modified nano-silica solution is 3-7 wt%; the constant temperature is 28-32℃.

[0044] The pulling number of the pulling method is 15-25, the pulling speed is 0.8-1.5 mm / s, and the residence time during the pulling process is 55-65 seconds; and the thickness of the obtained silica amorphous photonic crystal film is 1.0-1.2 mm.

[0045] The pulling method for preparing the photonic crystal film is conducive to improving the uniformity of discoloration and the independence of the observation angle.

[0046] S3. A polydimethylsiloxane prepolymer and a curing agent are uniformly mixed and degassed to obtain a PDMS solution, which is uniformly coated on both sides of the silica amorphous photonic crystal film obtained in step S2, and then heat-cured and demolded to obtain a force-induced discoloration film with low angle dependence and fatigue resistance.

[0047] Specifically, the polydimethylsiloxane prepolymer and the curing agent are uniformly mixed in a mass ratio of 10:1 by mechanical stirring, and degassed in a vacuum oven, and then uniformly coated on the surface of the silica amorphous photonic crystal, heat-cured in an oven at 75-85℃ for 1.5-2 hours, and then demolded to prepare a PDMS / SiO2 film; and then the PDMS solution is uniformly coated on the other side, heat-cured and demolded to prepare a force-induced discoloration film with low angle dependence and fatigue resistance with a "sandwich" structure of PDMS / modified SiO2 / PDMS, and the thickness is 2.0-3.2 mm.

[0048] The preparation method of the force-induced discoloration film with low angle dependence and fatigue resistance provided by the present application will be described below in combination with specific examples.

[0049] Example 1

[0050] Example 1 provides a preparation method of a force-induced discoloration film with low angle dependence and fatigue resistance, which comprises the following steps:

[0051] S1. Nanometer silica dioxide was prepared by sol-gel method. Specifically, reaction A liquid was prepared by adding 2 mL of ammonia water, 23 mL of deionized water and 50 mL of anhydrous ethanol into a 250 mL round-bottom flask and stirring at a speed of 1500 rap / min in a 30°C water bath for 10 min. Reaction B liquid was prepared by adding 9 mL of tetraethoxysilane and 41 mL of anhydrous ethanol into a 100 mL beaker and stirring magnetically for 10 min at room temperature. Reaction B liquid was quickly poured into A liquid, and the stirring speed was adjusted to 800 r / min after 2 min, and the reaction was stirred for 5 h. After the reaction was completed, the product was centrifuged for 8 min at a speed of 11000 r / min, the supernatant was removed, and then deionized water was poured in, ultrasonically dispersed and centrifuged again. Then, water washing and alcohol washing were performed twice in the same way to remove ammonia water. Finally, the product was dried in an 80°C oven, and then ground thoroughly with a mortar to obtain a white powder of nanometer silica dioxide with a particle size of 330 nm.

[0052] Reaction A liquid was prepared by mixing 1 g of dried nanometer SiO2 with (10 mL of ethanol + 10 mL of deionized water) and ultrasonically dispersing for 20 min. Reaction B liquid was prepared by adding 18 mL of ethanol and 2 mL of deionized water into a 50 mL beaker, adjusting the pH to 5 with oxalic acid, and adding 1 mL of KH570 into the weakly acidic alcohol-water medium with a pipette and stirring at room temperature for 1 h. Reaction A liquid was added to reaction B liquid, and the temperature was raised to 70°C. The reaction was carried out at this temperature for 6 h. After cooling to room temperature, the product was centrifuged at a speed of 1000 r / min for 5 min, and washed with anhydrous ethanol by ultrasonic dispersion for 5 times. Finally, the product was dried in an 80°C oven, and then ground thoroughly with a mortar to obtain a modified nanometer silica dioxide powder.

[0053] S2. A modified nanometer silica dioxide solution with a mass concentration of 5 wt% was prepared, and a silica amorphous photonic crystal film was prepared by the draw method at 30°C. Specifically, a hydrophilic glass slide was immersed in the photonic crystal solution at a speed of 1 mm / s for 60 s, and then taken out at the same speed. The draw was repeated for 20 times to prepare a low-angle-dependent silica amorphous photonic crystal film.

[0054] S3. The polydimethylsiloxane prepolymer and the curing agent were uniformly mixed by mechanical stirring at a mass ratio of 10:1, and then degassed in a vacuum oven. Then, the mixture was uniformly coated on the surface of the silica amorphous photonic crystal, and then heat cured in an 80°C oven for 2 h. Then, the PDMS / SiO2 film was prepared by demolding treatment. Then, the reverse side of the film was uniformly coated with a PDMS solution, and then heat cured at 80°C and demolded to obtain a PDMS / modified SiO2 / PDMS film with a thickness of 2.1 mm.

[0055] Example 2

[0056] Example 2 provides a preparation method of a mechano-chromic film with low angle dependence and fatigue resistance, compared with Example 1, the only difference is that the amount of ammonia is 4 mL, the particle size of the obtained nano-silicon dioxide is 290 nm, and other experimental parameters and conditions are basically the same as those of Example 1, which will not be repeated here.

[0057] Example 3

[0058] Example 3 provides a preparation method of a mechano-chromic film with low angle dependence and fatigue resistance, compared with Example 1, the only difference is that the amount of ammonia is 6 mL, the particle size of the obtained nano-silicon dioxide is 190 nm, and other experimental parameters and conditions are basically the same as those of Example 1, which will not be repeated here.

[0059] Comparative Example 1

[0060] Comparative Example 1 provides a preparation method of a mechano-chromic film with low angle dependence and fatigue resistance, compared with Example 1, the only difference is that a pure PDMS film with the same thickness is prepared, and other experimental parameters and conditions are basically the same as those of Example 1, which will not be repeated here.

[0061] Comparative Example 2

[0062] Comparative Example 2 provides a preparation method of a mechano-chromic film with low angle dependence and fatigue resistance, compared with Example 1, the only difference is that the nano-silicon dioxide is not modified with silane coupling agent KH570 to obtain a PDMS / SiO2 / PDMS film, and other experimental parameters and conditions are basically the same as those of Example 1, which will not be repeated here.

[0063] Figure 4 The scanning electron microscope images of the nano-SiO2 particles with different particle sizes prepared in Examples 1-3 of the present application are shown from left to right, with particle sizes of (a) 330 nm, (b) 290 nm, and (c) 190 nm. It can be seen that as the amount of ammonia increases (from left to right, the amount of ammonia is 2 mL, 4 mL, and 6 mL), the particle size of the nano-SiO2 particles gradually decreases, and the surface of the microspheres is very smooth without extrusion deformation, showing a good spherical shape.

[0064] Figure 5 The particle size distribution graph of the nano-SiO2 particles with different particle sizes prepared in Examples 1-3 of the present application is shown. It can be seen that the particle size of the SiO2 microspheres is normally distributed with a narrow distribution range, indicating that the SiO2 microspheres have good dispersibility in anhydrous ethanol without agglomeration.

[0065] Figure 6The related characterization figures of the nanometer silica microspheres prepared in Example 1 of the present application are shown in (a) FT-IR of the SiO2 microspheres before and after high-temperature calcination; (b) FT-IR of the SiO2 before and after modification; and (c) XRD of the SiO2 nanometer microspheres. As shown in (a), the absorption peaks of the stretching vibration of -CH3 and -CH2 disappear after calcination, indicating that the organic substances on the surface of the silica are removed by calcination. As shown in (b), the absorption peaks of the stretching vibration of -CH3 and -CH2 disappear after modification, indicating that the organic substances on the surface of the silica are removed by modification. As shown in (c), the SiO2 powder has only one wide diffraction peak near 23.5° before and after modification, indicating that the synthesized SiO2 belongs to an amorphous structure. -1 -1 -1 -1 -1

[0066] Figure 7 The digital photos of the silica amorphous photonic crystal films prepared in Examples 1-3 of the present application under different angles of diffuse light are shown in the figure, wherein sample 1, sample 2 and sample 3 represent the structural color films prepared from SiO2 with particle sizes of 330 nm, 190 nm and 290 nm respectively. It can be seen that the color of the structural color films prepared from SiO2 with different particle sizes does not change with the change of the angle under the indoor diffuse light.

[0067] Figure 8 The stress-strain curves of the films prepared in Example 1 and Comparative Examples 1-2 of the present application are shown in the figure. It can be seen that the mechanical properties of the PDMS / modified SiO2 / PDMS film prepared from the modified SiO2 are better than those of the unmodified SiO2 composite film, the breaking strength is close to that of the pure PDMS film, and the breaking strain only has a small decrease.

[0068] Figure 9 The cyclic tensile curves of the films prepared in Example 1 and Comparative Examples 1-2 of the present application are shown in the figure, wherein (a) and (b) are the cyclic tensile curves of the films prepared in Comparative Example 1 and Comparative Example 2 respectively, and (c) is the cyclic tensile curve of the film prepared in Example 1. It can be concluded that the carbon-carbon double bonds grafted on the surface of the modified SiO2 nanoparticles can react with the hydroxyl and mercapto groups on the surface of the PDMS to introduce covalent bonds, thereby enhancing the interfacial interaction between the inorganic silica nanoparticles and the PDMS, reducing the energy dissipation, and improving the elastic recovery performance of the material.

[0069] Figure 10 ​​​​​The information "display" and "erasing" effect figures of the thin film prepared for the embodiment 1 of the present application under different strains can be seen, after the PDMS / modified SiO2 / PDMS thin film is stretched, the periodic arrangement of the modified silica changes under different stretching strains (ε=0-72%), the light transmittance changes, the information can be displayed, after the external force is removed, the information is erased, the periodic structure of the silica can be deformed and recovered synchronously with the PDMS matrix, so that the color and information of the material can be reversibly changed.

[0070] In conclusion, the present application uses sol-gel method to prepare nano-silica photonic crystals with different particle sizes, due to the uniform particle size, the good dispersibility in ethanol, the periodic and regular arranged amorphous photonic crystal thin film can be prepared at a certain temperature, with hydrophilic glass slide as the base material, using the universal tensile testing machine with a certain pulling speed, which can be observed at different angles under indoor diffuse light with low angle dependence. The silica is modified by silane coupling agent KH570, the carbon-carbon double bond is grafted on the surface of the silica nanoparticles, which reacts with the hydroxyl and mercapto groups on the surface of PDMS, introduces chemical bonds, enhances the interface interaction between inorganic silica nanoparticles and PDMS, so as to improve the mechanical properties and fatigue resistance of the material, and the periodic structure of the silica can be deformed and recovered synchronously with the PDMS matrix, so that the color and information of the material can be reversibly changed.

[0071] The above embodiments are only used to illustrate the technical solutions of the present application but not limit the present application, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for preparing a mechanochromic thin film with low angle dependence and fatigue resistance, characterized in that, Includes the following steps: S1. Nano-silica was prepared by sol-gel method and modified with silane coupling agent KH570 to obtain modified nano-silica; S2. Prepare a modified nano-silica solution of a predetermined mass concentration, and prepare a silicon dioxide amorphous photonic crystal thin film by the Czochralski method at a constant temperature; the constant temperature is 28~32℃; The concentration of the modified nano-silica solution is 3~7wt%, and the thickness of the silicon dioxide amorphous photonic crystal film is 1.0~1.2mm; The lifting method involves 15 to 25 lifting cycles, a lifting speed of 0.8 to 1.5 mm / s, and a dwell time of 55 to 65 seconds during the lifting process. S3. The polydimethylsiloxane prepolymer and curing agent are mixed evenly and degassed to obtain a PDMS solution. The solution is then uniformly coated on both sides of the silica amorphous photonic crystal film prepared in step S2. After thermosetting and demolding, a mechanochromic film with low angle dependence and fatigue resistance is obtained.

2. The method for preparing the mechanochromic thin film with low angle dependence and fatigue resistance according to claim 1, characterized in that, In step S1, the particle size of the nano-silica is 190~330nm.

3. The method for preparing the mechanochromic thin film with low angle dependence and fatigue resistance according to claim 1, characterized in that, In step S3, the mass ratio of the polydimethylsiloxane prepolymer to the curing agent is 10:

1.

4. The method for preparing the mechanochromic thin film with low angle dependence and fatigue resistance according to claim 3, characterized in that, The thermosetting temperature is 75~85℃, and the time is 1.5~2h.

5. The method for preparing the mechanochromic thin film with low angle dependence and fatigue resistance according to claim 1, characterized in that, The thickness of the mechanochromic film with low angle dependence and fatigue resistance is 2.0~3.2mm.

6. A mechanochromic film with low angle dependence and fatigue resistance, characterized in that, It is prepared by the preparation method according to any one of claims 1-5.

7. An application of a mechanochromic film with low angle dependence and fatigue resistance, characterized in that, The mechanochromic film with low angle dependence and fatigue resistance as described in claim 6 can be used in the field of information encryption.

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