Stress resolution encryption material and preparation method thereof, structural color anti-counterfeit label and encryption method

Abstract

The invention relates to the technical field of polymer encryption materials, and discloses a stress resolution encryption material, a preparation method thereof, a structural color anti-counterfeit label and an encryption method. The stress resolution encryption material has a hard mask / flexible substrate double-layer structure, and the preparation method comprises the following steps: reacting an acrylic acid-co-acrylate copolymer solution with an anthracene derivative to obtain a hard mask material solution; the preparation method comprises the following steps: dissolving acrylate, diacetone acrylamide and an emulsifier in a solvent, and carrying out polymerization reaction under the action of an initiator to obtain an emulsion; curing and drying the emulsion to obtain a latex film; and coating the surface of the latex film with the hard film material solution. According to the stress resolution encryption material, stress programming exposure is carried out through the light source and the photomask, recording of structural color pattern information is achieved, the stress resolution encryption material has the strain resolution characteristic, and the optical performance of the surface changes along with changes of external stimulus. When the strain resolution encrypted information is read, external equipment is not needed, and the strain resolution encrypted information can be stretched by hands and identified by naked eyes.

Description

Technical Field

[0001] The present application relates to the technical field of polymer encryption materials, and in particular to a stress-resolving encryption material and a preparation method thereof, a structural color anti-counterfeiting label and an encryption method. Background Art

[0002] With the rapid development of science and technology, the importance of optical information encryption in the fields of personal identity authentication, currency security, commodity anti-counterfeiting and information storage has become increasingly prominent. At present, the research on optical information encryption mainly focuses on phosphorescence / fluorescence, metasurfaces and structural colors. Among them, structural colors have been widely used in optical encryption due to their low cost and easy identification.

[0003] However, traditional structural color anti-counterfeiting labels are easy to copy or imitate, and their encryption security is relatively low, which poses a great risk to information security. In addition, the preparation of traditional structural color labels relies on high-precision templates, and the preparation process is complicated; and they can only display a single encrypted information and cannot perform complex information encryption.

[0004] Based on this, in order to increase the complexity of structural color materials or enhance their responsiveness to external stimuli in order to improve the encryption security of structural color encryption materials, it is urgent to develop new encryption materials. Summary of the invention

[0005] The present application provides a stress-resolving encryption material and a preparation method thereof, a structural color anti-counterfeiting label and an encryption method, aiming to solve the problems of low encryption security, complex preparation process and difficulty in performing complex information encryption in existing structural color anti-counterfeiting labels.

[0006] In order to achieve the above objectives, the present application adopts the following technical solutions.

[0007] In a first aspect of the present application, a stress-resolving encryption material is provided, wherein the stress-resolving encryption material has a hard film / flexible substrate double-layer structure;

[0008] The chemical structure of the hard film material is shown in formula (1):

[0009]

[0010] The flexible substrate is a latex film, and the chemical structure of the latex film material is shown in formula (2):

[0011]

[0012] Wherein, R is any one of C1-20 aryl, C1-20 heterocyclic aromatic, C1-20 alkyl, C1-20 acyl, C1-20 ester, C1-20 ketone, C1-20 aldehyde, C1-20 alkoxy, and C1-20 aryloxy;

[0013] R' is a C1-20 nitrogen-containing heterocyclic aromatic group, a C1-20 ester group, a C1-20 alkoxy group, or a C1-20 carboxylic acid group;

[0014] Among them, m+n=1, 0.5≤m≤0.9; p+q=1, 0.05≤p≤0.1.

[0015] The second aspect of the present application provides a method for preparing the above-mentioned stress-resolving encryption material, comprising:

[0016] dissolving acrylic acid and acrylic ester in an organic solvent, reacting them under the action of a first initiator to obtain an acrylic acid-co-acrylic ester copolymer solution; adding an anthracene derivative to the acrylic acid-co-acrylic ester copolymer solution, reacting them under the catalysis of sulfuric acid to obtain a hard film material solution;

[0017] Dissolving acrylate, diacetone acrylamide and an emulsifier in a second solvent, and performing a polymerization reaction under the action of a second initiator; adding a curing agent to the emulsion after the reaction, and stirring evenly; pouring the emulsion into a mold, and drying to obtain a latex film;

[0018] The hard film material solution is coated on the surface of the latex film to obtain a stress-resolving encryption material of the hard film / flexible substrate.

[0019] Preferably, the anthracene derivatives include any mono- or poly-substituted derivatives of anthracene's C1-20 aromatic groups, C1-20 heterocyclic aromatic groups, C1-20 alkyl groups, C1-20 acyl groups, C1-20 ester groups, C1-20 ketone groups, C1-20 aldehyde groups, C1-20 alkoxy groups or C1-20 aryloxy groups.

[0020] Preferably, the molar amount of the anthracene derivative is 5% to 100% of the molar amount of acrylic acid.

[0021] Preferably, the molar ratio of the acrylate, diacetone acrylamide, emulsifier and initiator is 30:0.3:0.3:0.04.

[0022] Preferably, the organic solvent includes at least one of 1,4-dioxane, N,N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, furan, pyridine, chloroform or dichloromethane;

[0023] Preferably, the temperature at which the acrylic acid and the acrylate react is 20 to 100° C.;

[0024] The polymerization reaction temperature of the acrylic acid ester and diacetone acrylamide is 20-100°C.

[0025] The first initiator includes at least one of azobisisobutyronitrile, azobisisoheptanenitrile or dimethyl azobisisobutyrate.

[0026] Preferably, the emulsifier includes any one of oleic acid, sorbitan esters, polyoxyethylene esters or dodecyl sulfate;

[0027] The second initiator includes any one of benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, diisopropyl peroxide, tert-butyl perbenzoate, tert-butyl pervalerate, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, potassium persulfate, sodium persulfate or ammonium persulfate;

[0028] The second solvent includes at least one of water, methanol, ethanol, acetonitrile, tetrahydrofuran, acetone, cyclopentanone, cyclohexanone, dichloromethane, chloroform, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, dioxane, hexafluoroisopropanol, cyclopentane, N-methyl-2-pyrrolidone, m-cresol, xylenol, benzene, toluene, xylene, N-vinyl-2-pyrrolidone, butyrolactone, and butyl acetate.

[0029] In a third aspect of the present application, a structural color anti-counterfeiting label is provided, which includes the above-mentioned stress-resolving encryption material.

[0030] In a fourth aspect of the present application, there is provided an encryption method, comprising: placing the stress-resolving encryption material in a stretched state, and exposing a specific area thereof with ultraviolet light and a photomask, and recording encryption information on the surface thereof; when the stress-resolving encryption material returns to an original state, the encryption information is displayed;

[0031] or,

[0032] The stress-resolving encryption material is placed in a first tensile state, and is exposed to light for t1 time in a first specific area thereof using ultraviolet light and a photomask, and first encryption information is recorded; the stress-resolving encryption material is placed in a second tensile state, and is exposed to light for t2 time in the first specific area thereof using ultraviolet light and a photomask, and second encryption information is recorded; wherein the strain amount in the first tensile state is greater than the strain amount in the second tensile state, and t1>t2;

[0033] When the stress-resolving encryption material is in a first tensile state, the first encrypted information is displayed and the second encrypted information disappears; when the stress-resolving encryption material is in a second tensile state or an original state, the first encrypted information disappears and the second encrypted information is displayed.

[0034] Compared with the prior art, the beneficial effects of this application are:

[0035] The stress-resolved encryption material of the present application is exposed by stress programming through a light source and a photomask to achieve the burning of structural color encryption information and form a wrinkle pattern on its surface; it has a "strain resolution" characteristic, and the wrinkle pattern can evolve with the change of the tensile strain of the stress-resolved encryption material, giving the material surface the characteristic of optical properties changing with external stimuli. The stress-resolved encryption material of the present application can be directly used as a structural color anti-counterfeiting label or used to prepare a structural color anti-counterfeiting label. Its preparation process is simple and does not require a high-precision template. It has unique advantages in preparing large-area periodic micro-nano structures.

[0036] After different areas of the stress-resolved encryption material of the present application are exposed for different lengths of time under different tensile strains, the structural color pattern can appear in the order of tensile strain; the strain-resolved encrypted information does not require external equipment when reading, and can be stretched by hand and identified by the naked eye. Compared with phosphorescence encryption and traditional structural color encryption, it has higher encryption security and economic and practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0038] Figure 1 This is an angle-resolved reflection spectrum diagram of the stress-resolved encryption material of Example 1 when it recovers to its original length after exposure;

[0039] Figure 2 This is a diagram showing the stress-resolving encryption material of Example 1 recovering the original long-term encryption information after exposure;

[0040] Figure 3 This is a diagram showing the encrypted information of the original length and stretched state of the stress-resolved encrypted material of Example 2 after being exposed to different stretching strains and different time regions. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0042] In the following description of this embodiment, the terms "include", "comprising", "having" and "containing" are all open terms, meaning including but not limited to.

[0043] In the following description of this embodiment, the term "and / or" is used to describe the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, B exists alone, and A and B exist at the same time. A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0044] In the following description of this embodiment, the term "at least one" refers to one or more, and "plurality" refers to two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b or c", or "at least one of a, b and c", can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively.

[0045] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0046] Those skilled in the art should understand that in the following description of the embodiments of the present application, the order of serial numbers does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0047] Those skilled in the art will appreciate that the numerical ranges in the embodiments of the present application are to be construed as specifically disclosing each intermediate value between the upper and lower limits of the scope. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present application. The upper and lower limits of these smaller ranges may be independently included or excluded in the scope.

[0048] Unless otherwise specified, the technical / scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which this application belongs. Although this application only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of this application. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0049] In a first aspect, the present application provides a stress-resolving encryption material having a hard film / flexible substrate double-layer structure;

[0050] The chemical structure of the hard film material is shown in formula (1):

[0051]

[0052] Wherein, R is any one of C1-20 aryl, C1-20 heterocyclic aromatic, C1-20 alkyl, C1-20 acyl, C1-20 ester, C1-20 ketone, C1-20 aldehyde, C1-20 alkoxy, and C1-20 aryloxy;

[0053] m and n are the molar ratios of the comonomers, m+n=1, 0.5≤m≤0.9;

[0054] The flexible substrate is a latex film, and the chemical structure of the latex film material is shown in formula (2):

[0055]

[0056] Wherein, R' is C1-20 nitrogen-containing heterocyclic aromatic group, C1-20 ester group, C1-20 alkoxy group, C1-20 carboxylic acid group; p and q are the molar ratio of the comonomer, p+q=1, 0.05≤p≤0.1.

[0057] The stress-resolving encryption material of the present application is exposed by stress programming through a light source and a photomask to realize the burning of a structural color pattern and form a wrinkle pattern on its surface; it has the characteristic of "strain resolution", and the wrinkle pattern can evolve with the change of the tensile strain of the stress-resolving encryption material, giving the optical properties of the material surface the characteristic of changing with external stimuli. It can be directly used as a structural color anti-counterfeiting label or used to prepare a structural color anti-counterfeiting label.

[0058] The preparation method of the stress-resolving encryption material of the present application comprises:

[0059] Preparation of hard film material: dissolving acrylic acid and acrylic ester in an organic solvent, reacting at 20-100° C. under the action of a first initiator to obtain an acrylic acid-co-acrylic ester copolymer solution; adding an anthracene derivative to the acrylic acid-co-acrylic ester copolymer solution, reacting under the catalysis of sulfuric acid to obtain a hard film material solution;

[0060] The first initiator is used to initiate a copolymerization reaction between acrylic acid and acrylic ester to generate an acrylic acid-co-acrylic ester copolymer; the first initiator includes at least one of azobisisobutyronitrile, azobisisoheptanenitrile or dimethyl azobisisobutyrate.

[0061] The anthracene derivative is used to react with an acrylic acid-co-acrylate copolymer to generate a hard film material and introduce a photosensitive group; the anthracene derivative is selected from any monosubstituted or polysubstituted derivative of anthracene's C1-20 aromatic groups, C1-20 heterocyclic aromatic groups, C1-20 alkyl groups, C1-20 acyl groups, C1-20 ester groups, C1-20 ketone groups, C1-20 aldehyde groups, C1-20 alkoxy groups or C1-20 aryloxy groups.

[0062] The organic solvent includes at least one of 1,4-dioxane, N,N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, furan, pyridine, chloroform or dichloromethane.

[0063] In the present application, the molar ratio of acrylic acid to acrylic ester is preferably 3:7; and the molar number of the anthracene derivative is preferably 5% to 100% of the molar number of acrylic acid.

[0064] Preparation of latex film: dissolving acrylate, diacetone acrylamide and emulsifier in a second solvent, and polymerizing at 20-100° C. under the action of a second initiator; adding a curing agent to the latex after the reaction, and stirring evenly; pouring the latex into a mold, drying at 60° C., and removing moisture to obtain a latex film;

[0065] Wherein, the second initiator is used to initiate the polymerization reaction of acrylate and diacetone acrylamide, and the second initiator includes any one of benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, diisopropyl peroxybenzoate, tert-butyl peroxyvalerate, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, potassium persulfate, sodium persulfate or ammonium persulfate.

[0066] The emulsifier includes any one of oleic acid, sorbitan esters, polyoxyethylene esters or dodecyl sulfate; and the curing agent is adipic dihydrazide.

[0067] The second solvent includes at least one of water, methanol, ethanol, acetonitrile, tetrahydrofuran, acetone, cyclopentanone, cyclohexanone, dichloromethane, chloroform, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, dioxane, hexafluoroisopropanol, cyclopentane, N-methyl-2-pyrrolidone, m-cresol, xylenol, benzene, toluene, xylene, N-vinyl-2-pyrrolidone, butyrolactone, and butyl acetate.

[0068] In the present application, the molar ratio of acrylate, diacetone acrylamide, emulsifier and initiator is preferably 30:0.3:0.3:0.04.

[0069] Preparation of stress-resolving encryption material: coating a hard film material solution on the surface of a latex film to obtain a stress-resolving encryption material of a hard film / flexible substrate.

[0070] Wherein, the coating is performed by spin coating, and the spin coating speed ranges from 300rpm to 9500rpm.

[0071] The present application also provides a structural color anti-counterfeiting label, which includes the stress-resolving encryption material of the present application.

[0072] The stress-resolving encryption material of the present application is a method of combining stretching with ultraviolet light exposure. After different regions are exposed to different tensile strains for different lengths of time, the structural color pattern can appear in the order of tensile strain. It can be directly used as a structural color anti-counterfeiting label or used to prepare a structural color anti-counterfeiting label. Its preparation process is simple and does not require a high-precision template. It has unique advantages in preparing large-area periodic micro-nano structures.

[0073] The present application also provides an encryption method, which places the above-mentioned stress-resolving encryption material in a stretched state, and uses ultraviolet light and a photomask to expose specific areas thereof, and records encrypted information on its surface; when the stress-resolving encryption material returns to its original state, the encrypted information is displayed.

[0074] This application also provides another encryption method, which can achieve strain-resolved encryption. The method specifically includes:

[0075] The stress-resolving encryption material is placed in a first stretched state, and exposed to the first specific area for t1 time using ultraviolet light and a photomask, and the first encrypted information is recorded; the stress-resolving encryption material is placed in a second stretched state, and exposed to the first specific area for t2 time using ultraviolet light and a photomask, and the second encrypted information is recorded. The wavelength of the ultraviolet light used for exposure is 300-400nm, and the wavelength of the ultraviolet light is preferably 365nm.

[0076] In the present application, the strain in the first tensile state is greater than the strain in the second tensile state, and t1>t2; preferably, the strain in the first tensile state and the strain in the second tensile state are 50% to 500%, and the strain fixing time is 0 to 600s; the variation range of t1 and t2 is 5 to 600s.

[0077] When the stress-resolving encryption material is in a first tensile state, the first encrypted information is displayed and the second encrypted information disappears; when the stress-resolving encryption material is in a second tensile state or an original state, the first encrypted information disappears and the second encrypted information is displayed.

[0078] The strain-resolved encryption method of the present application does not require external equipment when reading the encrypted information, and can be stretched by hand and identified by the naked eye. Compared with phosphorescence encryption and traditional structural color encryption, it has higher encryption security and economic and practical value.

[0079] The present application is further described below by way of examples.

[0080] Example 1

[0081] This embodiment provides a method for preparing a stress-resolving encryption material, comprising:

[0082] S1, add 18.07g of methyl acrylate and 6.48g of acrylic acid into a flask, add 100mL of dioxane to dissolve, then add 0.24g of azobisisobutyronitrile, deoxygenate and seal, heat the mixture to 70°C and react for 12h to obtain an acrylic acid-co-acrylic acid ester copolymer solution. Add 18.71g of 9-anthracene methanol to the acrylic acid-co-acrylic acid ester copolymer solution, then add sulfuric acid to catalyze the reaction, and obtain a hard film material solution after the reaction is completed.

[0083] The synthesis process is as follows:

[0084]

[0085] S2, 0.1g of ammonium persulfate, 1g of sodium dodecylbenzene sulfonate, 0.5077g of diacetone acrylamide and 30g of ethyl acrylate are added to 60mL of distilled water to mix and form an emulsion, slowly heated to 70°C, and kept warm for 3h to react to obtain an emulsion. The emulsion is then cooled to room temperature and 0.2613g of adipic dihydrazide is added to obtain a self-crosslinking emulsion. The self-crosslinking emulsion is transferred to a mold, dried and cured at 60°C to obtain a latex film.

[0086] S3, spin coating the hard film material solution onto the surface of the latex film at a rotation speed of 500 rpm to form a hard film / flexible substrate double-layer system, thereby obtaining a stress-resolving encryption material.

[0087] Example 2

[0088] S1, add 26.93g of butyl acrylate and 6.48g of acrylic acid into a flask, add 100mL of dioxane to dissolve, then add 0.24g of azobisisobutyronitrile, deoxygenate and seal, heat the mixture to 70°C and react for 12h to obtain an acrylic acid-co-acrylic acid ester copolymer solution. Add 18.71g of 9-anthracene methanol to the acrylic acid-co-acrylic acid ester copolymer solution, then add sulfuric acid to catalyze the reaction, and obtain a hard film material solution after the reaction is completed.

[0089] The synthesis process is as follows:

[0090]

[0091] S2, 0.1g of ammonium persulfate, 1g of sodium dodecylbenzene sulfonate, 0.5077g of diacetone acrylamide and 30g of ethyl acrylate are added to 60mL of distilled water to mix and form an emulsion, slowly heated to 70°C, and kept warm for 3h to react to obtain an emulsion. The emulsion is then cooled to room temperature and 0.2613g of adipic dihydrazide is added to obtain a self-crosslinking emulsion. The self-crosslinking emulsion is transferred to a mold, dried and cured at 60°C to obtain a latex film.

[0092] S3, spin coating the hard film material solution onto the surface of the latex film at a rotation speed of 500 rpm to form a hard film / flexible substrate double-layer system, thereby obtaining a stress-resolving encryption material.

[0093] The stress-resolving encryption material prepared in Example 1 is used as a structural color anti-counterfeiting label for encryption, and the specific methods include the following two methods:

[0094] 1. The stress-resolving encryption material of Example 1 was stretched with a fixed strain of 30%, and exposed to ultraviolet light with a wavelength of 365 nm and a mask for 5 seconds. After the original length was restored, the surface of the stress-resolving encryption material changed from a smooth state before illumination to a wrinkled state with structural color encryption information. Figure 1 This is the angle-resolved reflectance spectrum of the stress-resolved encrypted material of Example 1 when it is restored to its original length. This phenomenon proves the formation of wrinkles.

[0095] 2. The stress-resolving encryption material of Example 1 was stretched, the strain was fixed at 30%, and it was exposed to ultraviolet light with a wavelength of 365nm and a mask with a specific number "3" pattern for 5s. After the original length was restored, it was observed that the material surface had structural color encryption information "3", such as Figure 2 As shown, after the photomask stretching exposure process, encrypted information "3" with structural color appears on the wrinkled surface, and its color changes with the change of the light source angle.

[0096] The stress-resolving encryption material prepared in Example 2 is used as a structural color anti-counterfeiting label for encryption, and the specific method is as follows:

[0097] The stress-resolving encryption material of Example 2 is stretched to 50% strain, and a region of the surface is exposed for 120 seconds using ultraviolet light with a wavelength of 365 nm and a mask with a specific number "1" pattern, and then a region of the surface is exposed for 30 seconds using ultraviolet light with a wavelength of 365 nm and a mask with a specific number "2" pattern. After the stress-resolving encryption material recovers its original length, the surface presents an encrypted number "2", as shown in FIG. Figure 3 As shown in (a); when the stress-resolving encrypted material is stretched by 50% strain, the encrypted number "2" appears on its surface, and the encrypted number "2" disappears at the same time, as shown in Figure 3(b) When stress-resolving encryption materials are subjected to specific optical programming, encryption patterns can appear sequentially as strain increases, which has the characteristic of "strain resolution".

[0098] Although the present application has been described in detail in general terms and in specific embodiments in this specification, it is obvious to those skilled in the art that some modifications or improvements may be made to the present application. Therefore, these modifications or improvements made without departing from the spirit of the present application are within the scope of protection claimed in the present application.

Claims

1. A stress-resolving encryption material, characterized in that: The stress-resolving encryption material has a hard film / flexible substrate double-layer structure; The chemical structure of the hard film material is shown in formula (1): The flexible substrate is a latex film, and the chemical structure of the latex film material is shown in formula (2): Wherein, R is any one of C1-20 aryl, C1-20 heterocyclic aromatic, C1-20 alkyl, C1-20 acyl, C1-20 ester, C1-20 ketone, C1-20 aldehyde, C1-20 alkoxy, and C1-20 aryloxy; R' is a C1-20 nitrogen-containing heterocyclic aromatic group, a C1-20 ester group, a C1-20 alkoxy group, or a C1-20 carboxylic acid group; Among them, m+n=1, 0.5≤m≤0.9; p+q=1, 0.05≤p≤0.

1.

2. The method for preparing the stress-resolving encryption material according to claim 1, characterized in that: include: dissolving acrylic acid and acrylic ester in an organic solvent, reacting them under the action of a first initiator to obtain an acrylic acid-co-acrylic ester copolymer solution; adding an anthracene derivative to the acrylic acid-co-acrylic ester copolymer solution, reacting them under the catalysis of sulfuric acid to obtain a hard film material solution; Dissolving acrylate, diacetone acrylamide and an emulsifier in a second solvent, and performing a polymerization reaction under the action of a second initiator; adding a curing agent to the emulsion after the reaction, and stirring evenly; pouring the emulsion into a mold, and drying to obtain a latex film; The hard film material solution is coated on the surface of the latex film to obtain a stress-resolving encryption material of the hard film / flexible substrate.

3. The preparation method according to claim 2, characterized in that: The anthracene derivatives include any mono- or poly-substituted derivatives of anthracene of C1-20 aryl, C1-20 heterocyclic aromatic, C1-20 alkyl, C1-20 acyl, C1-20 ester, C1-20 ketone, C1-20 aldehyde, C1-20 alkoxy or C1-20 aryloxy.

4. The preparation method according to claim 2, characterized in that: The molar number of the anthracene derivative is 5% to 100% of the molar number of acrylic acid.

5. The preparation method according to claim 2, characterized in that: The molar ratio of the acrylate, diacetone acrylamide, emulsifier and initiator is 30:0.3:0.3:0.

04.

6. The preparation method according to claim 2, characterized in that: The organic solvent includes at least one of 1,4-dioxane, N,N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, furan, pyridine, chloroform or dichloromethane; The first initiator includes at least one of azobisisobutyronitrile, azobisisoheptanenitrile or dimethyl azobisisobutyrate.

7. The preparation method according to claim 2, characterized in that: The emulsifier includes any one of oleic acid, sorbitan esters, polyoxyethylene esters or lauryl sulfate; The second initiator includes any one of benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, diisopropyl peroxide, tert-butyl perbenzoate, tert-butyl pervalerate, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, potassium persulfate, sodium persulfate or ammonium persulfate; The second solvent includes at least one of water, methanol, ethanol, acetonitrile, tetrahydrofuran, acetone, cyclopentanone, cyclohexanone, dichloromethane, chloroform, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, dioxane, hexafluoroisopropanol, cyclopentane, N-methyl-2-pyrrolidone, m-cresol, xylenol, benzene, toluene, xylene, N-vinyl-2-pyrrolidone, butyrolactone, and butyl acetate.

8. The preparation method according to claim 2, characterized in that: The temperature at which the acrylic acid and the acrylate react is 20 to 100° C.; The polymerization temperature of the acrylic acid ester and diacetone acrylamide is 20-100°C.

9. A structural color anti-counterfeiting label, characterized in that: It includes the stress-resolving encryption material as claimed in claim 1.

10. An encryption method, characterized in that: include: The stress-resolving encryption material of claim 1 is placed in a stretched state, and exposed to light using ultraviolet light and a photomask in a specific area thereof, thereby recording encryption information on the surface thereof; When the stress-resolving encryption material returns to its original state, the encrypted information is displayed; or, The stress-resolving encryption material is placed in a first tensile state, and is exposed to light for t1 time in a first specific area thereof using ultraviolet light and a photomask, and first encryption information is recorded; the stress-resolving encryption material is placed in a second tensile state, and is exposed to light for t2 time in the first specific area thereof using ultraviolet light and a photomask, and second encryption information is recorded; wherein the strain in the first tensile state is greater than the strain in the second tensile state, and t1>t2; When the stress-resolving encryption material is in a first tensile state, the first encryption information is displayed and the second encryption information disappears; When the stress-resolving encryption material is in the second stretched state or the original state, the first encryption information disappears and the second encryption information is displayed.

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