Dynamic anti-counterfeit label based on magnetic control birefringence effect and preparation and verification method thereof

Abstract

The invention discloses a magnetic control birefringence effect-based dynamic anti-counterfeit label and a preparation and verification method thereof. The anti-counterfeit label comprises a transparent protective layer, a magneto-optical functional layer, a patterned reflecting layer, a bonding layer and a substrate layer which are sequentially arranged from top to bottom, the magneto-optical functional layer is formed by compounding magnetic nanorods and a polymer matrix, the spatial orientation of the nanorods is adjusted by using an external magnetic field, so that the polarization state and phase of reflected light are adjusted and controlled, the patterned reflecting layer bears optical information, the characteristics of the reflected light dynamically change along with the change of the magnetic field, and the reflected light cannot be imitated through a traditional printing technology. And a magnetic field angle dependent color developing anti-counterfeiting function is realized. When the external magnetic field changes, the reflection pattern changes accordingly, and real-time and dynamically verifiable anti-counterfeiting characteristics can be provided. The transparent protective layer, the magneto-optical functional layer, the patterned reflecting layer, the bonding layer and the substrate layer are compositely stacked, so that the long-term reliability of the anti-counterfeiting performance can be ensured, and the anti-counterfeiting film is suitable for outdoor products, industrial equipment and other application scenes with higher requirements on temperature.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of anti-counterfeiting technology, and in particular to a dynamic anti-counterfeiting label based on magnetic control birefringence effect and a preparation and verification method thereof. BACKGROUND

[0002] Counterfeit goods not only seriously infringe the legitimate rights and interests of brand owners and consumers, but also have become an urgent need to protect the healthy operation of economic activities to develop efficient, reliable and difficult-to-crack anti-counterfeiting technology.

[0003] The current mainstream anti-counterfeiting technology has many defects in the face of modern counterfeiting methods, including high technical replicability, high cost, lack of dynamic interaction, non-unique anti-counterfeiting features, unreliable naked eye recognition and untrustworthy traceability information. For example, static visual features such as holographic diffraction fringes and microtext can be perfectly replicated through high-resolution scanning combined with nanoimprint technology; although electronic anti-counterfeiting technologies such as NFC chips have the advantages of fast reading, large data capacity and strong encryption, their high cost limits their popularity in low-cost goods. In addition, in an electromagnetic shielding environment, such technologies may fail, thereby reducing their reliability in certain scenarios; optical color-changing materials can produce color changes at specific angles, but such changes are limited and can only be observed at specific viewing angles. Most of them rely on a single physical or chemical property and lack a mechanism for multi-parameter synergy. No technology combines magnetic fields, optical properties, etc. to form a dynamic anti-counterfeiting effect that users can perceive in real time.

[0004] Therefore, it is necessary to develop a dynamic anti-counterfeiting technology with multi-parameter synergy and user perception, combine multiple technical means to build a multi-level anti-counterfeiting system, and lay the foundation for developing a new generation of anti-counterfeiting system with dynamic interaction, non-replicability and easy verification. SUMMARY

[0005] Therefore, the present application provides a solution to the technical problem that existing anti-counterfeiting labels are easy to be copied and imitated and cannot achieve a dynamic anti-counterfeiting effect that users can perceive in real time.

[0006] To achieve the above technical purpose, the present application adopts the following technical solutions: In a first aspect, the present application provides a preparation method of a dynamic anti-counterfeiting label based on magnetic control birefringence effect, comprising: preparing a magneto-optical functional layer; the magneto-optical functional layer comprises a composite structure of magnetic nanorods and a polymer matrix, which is used to control the spatial orientation of the nanorods through an external magnetic field, modulate the polarization state and phase of reflected light, and realize a magnetic field angle-dependent color development anti-counterfeiting function; preparing a patterned reflective layer; the patterned reflective layer is used to carry optical information and reflect ambient light as a reflection surface; The transparent protective layer, the magneto-optical functional layer, the patterned reflective layer, the adhesive layer and the substrate layer are sequentially laminated by a multi-layer composite process; the transparent protective layer is used to provide mechanical support and optical coupling, to ensure the overall flatness and light transmission efficiency of the label; the adhesive layer is used to firmly bond the label with the adherend; and the substrate layer is used to protect the adhesive layer and provide structural strength for the overall label.

[0007] Further, the preparation of the magneto-optical functional layer comprises: The magnetic nanorods are mixed with the ultraviolet light-cured polymer at a preset filling density, a dispersing agent is added and stirred uniformly to prevent the nanorods from agglomerating, to obtain a magneto-optical composite slurry; The magneto-optical composite slurry is coated on a release film, and the nanorods are directionally arranged in space under the action of a pulsed magnetic field; The UV curing and shaping operation is performed under the condition that the magnetic field is maintained, so that the polymer is completely cured, and the spatial orientation of the nanorods is permanently fixed.

[0008] Further, the magnetic nanorods are ferromagnetic nanorods, the aspect ratio is 8:1 to 15:1, the diameter ranges from 150 nm to 250 nm, and the length ranges from 1.6 μm to 3 μm.

[0009] Further, the spatial orientation of the nanorods is controlled by an external magnetic field to modulate the polarization state and phase of the reflected light, to realize the color development anti-counterfeiting function dependent on the angle of the magnetic field, which comprises: Based on the magnetic birefringence equation, the spatial orientation of the nanorods is adjusted to obtain the corresponding birefringence; According to the birefringence, the polarization state and phase of the light reflected by the patterned reflective layer are modulated, to realize the dynamic hiding, appearing and continuous color change of the pattern.

[0010] Further, the preparation of the patterned reflective layer comprises: The release film with the magneto-optical functional layer is used as a substrate, and a holographic microstructure is molded on the surface of the substrate; A metal reflective layer is deposited on the surface of the molded substrate by vacuum evaporation; A laser micro-sculpting technology is used to etch the metal reflective layer to form a patterned reflective layer.

[0011] Further, the multi-layer composite process comprises: A transparent PET film is laminated as a transparent protective layer by a UV-cured pressure-sensitive adhesive layer, and the pressure-sensitive adhesive is cured by a UV curing operation; The same method is used to complete the lamination of the magneto-optical functional layer and the patterned reflective layer, the patterned reflective layer and the adhesive layer, and the adhesive layer and the substrate layer; The laminated material is die-cut to obtain anti-counterfeiting labels of a preset size.

[0012] Secondly, the present invention also provides a dynamic anti-counterfeiting label based on the magnetron birefringence effect, which is made using the above scheme and includes, from top to bottom, the following layers arranged in sequence: a transparent protective layer, a magneto-optical functional layer, a patterned reflective layer, an adhesive layer, and a base layer. The transparent protective layer is used to provide mechanical protection for the label and allow ambient light to pass through; The magneto-optical functional layer comprises oriented ferromagnetic nanorods, which are used to modulate the polarization state and phase of the reflected light from the reflective layer under changes in the direction of an external magnetic field. The patterned reflective layer is configured to carry anti-counterfeiting patterns and reflect light incident on it back to the magneto-optical functional layer. The adhesive layer is used to fix the label to the surface of the object to be affixed; The base layer is used to provide structural strength and stability for the entire label.

[0013] Thirdly, the present invention also provides a method for verifying anti-counterfeiting labels, used to verify anti-counterfeiting labels of the above-mentioned technical solutions, comprising: A permanent magnet is brought close to or attached to the anti-counterfeiting label, which includes a magneto-optical functional layer and a patterned reflective layer. Change the angle between the magnetic field direction of the permanent magnet and the normal to the label plane; The dynamic optical response of the pattern on the patterned reflective layer as the included angle changes is observed to verify authenticity.

[0014] Furthermore, the dynamic optical response of the pattern on the patterned reflective layer as the included angle changes is observed to verify authenticity, including: When the included angle is around 0° or 90°, the pattern disappears or becomes invisible, and when the included angle is around 45°, the pattern becomes clearly visible, proving that the anti-counterfeiting label is genuine.

[0015] Furthermore, the observation steps include: identifying holographic diffraction rings or iridescent optical effects that appear at a specific angle.

[0016] Compared with existing technologies, the dynamic anti-counterfeiting label based on magnetron birefringence effect and its preparation and verification methods proposed in this invention have the following advantages: (1) By designing a composite structure of magnetic nanorods and polymer matrix in the magneto-optical functional layer, the spatial orientation of the nanorods can be controlled by an external magnetic field, thereby modulating the polarization state and phase of the reflected light. Utilizing the magneto-optical coupling effect, the anti-counterfeiting properties of the label cannot be replicated by traditional printing techniques. The spatial orientation of the magnetic nanorods can only be controlled by an external magnetic field, giving each label unique optical properties, effectively preventing counterfeiting and providing a high level of security.

[0017] (2) By patterning the reflective layer as a carrier to bear optical information, effectively reflecting ambient light, and showing unique visual effects, the pattern of the label has the characteristics of continuous change with the magnetic field, and the user can verify the authenticity of the label in real time by changing the angle of the magnetic field. For example, the pattern will present different reflection effects between 0°, 45°, 90°, etc. Angle, making the verification process more intuitive and dynamic. This anti-counterfeiting verification is not only more flexible, but also difficult to be static copied.

[0018] (3) By using the superimposed transparent protective layer, magneto-optical functional layer, patterned reflective layer, adhesive layer and substrate layer of the multi-layer composite process, the synergistic effect between each layer greatly improves the comprehensive performance of the label. The transparent protective layer provides excellent optical coupling effect and mechanical support, ensuring the flatness and light transmission efficiency of the label; the adhesive layer and the substrate layer ensure that the label is firmly bonded to the object to be pasted, while protecting the stability and structural strength of the label, enhancing the performance of the label in anti-counterfeiting, security, durability and visual effect, and can work stably in the extreme temperature range of-40℃ to 85℃, widely applicable to outdoor products, industrial equipment and other applications with high temperature requirements, ensuring the long-term reliability of the anti-counterfeiting performance. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The preparation method of the dynamic anti-counterfeiting label based on the magnetic control birefringence effect provided by the present application is shown in the flowchart. Figure 2 The structure diagram of an embodiment of the magneto-optical functional layer provided by the present application is shown in the structure diagram. Figure 3 The structure diagram of the dynamic anti-counterfeiting label based on the magnetic control birefringence effect provided by the present application is shown in the structure diagram. Figure 4 The dynamic change sequence diagram of the pattern of the false label under the magnetic field angle of 0° / 45° / 90° is shown in the dynamic change sequence diagram. Figure 5 The response effect diagram of the anti-counterfeiting label under different magnetic field angles is shown in the response effect diagram. Figure 6 The verification effect diagram provided by the present application is shown in the verification effect diagram. DETAILED DESCRIPTION

[0020] The preferred embodiments of the present application will be specifically described below in conjunction with the drawings, wherein the drawings constitute a part of the present application, and are used together with the embodiments of the present application to explain the principles of the present application, but not to limit the scope of the present application.

[0021] Example 1 Please see Figure 1 The preparation method of the dynamic anti-counterfeiting label based on the magnetic control birefringence effect provided by the present application is shown in the flowchart. Step S101: Prepare a magneto-optical functional layer; the magneto-optical functional layer includes a composite structure of magnetic nanorods and a polymer matrix, which is used to control the spatial orientation of the nanorods through an external magnetic field, modulate the polarization state and phase of the reflected light, and realize a magnetic field angle-dependent color-developing anti-counterfeiting function. Step S102: Prepare a patterned reflective layer; the patterned reflective layer is used to carry optical information and serves as a reflective surface to reflect ambient light; Step S103: The transparent protective layer, magneto-optical functional layer, patterned reflective layer, adhesive layer and base layer are sequentially stacked through a multi-layer composite process; the transparent protective layer is used to provide mechanical support and optical coupling to ensure the overall flatness and light transmission efficiency of the label; the adhesive layer is used to firmly bond the label to the object to be applied; the base layer is used to protect the adhesive layer and provide structural strength for the overall label.

[0022] This embodiment presents a method for fabricating dynamic anti-counterfeiting labels based on magneto-controlled birefringence. First, the magneto-optical functional layer controls the orientation of nanorods through an external magnetic field, modulating the polarization state and phase of reflected light to provide high-precision, angle-dependent color-changing anti-counterfeiting functionality, significantly enhancing the label's anti-counterfeiting capabilities. Second, the patterned reflective layer not only carries optical information but also displays unique visual effects under illumination, enhancing the label's recognizability and visibility. Finally, a multi-layer composite process is employed, with a transparent protective layer ensuring mechanical support and optical coupling, and an adhesive and base layer enhancing the label's robustness and structural strength, making it more durable and possessing long-term stability. This method provides the label with significant advantages in anti-counterfeiting, security, durability, and visual appeal, making it suitable for anti-counterfeiting protection of high-end goods, important documents, and smart products.

[0023] In some embodiments, such as Figure 2 As shown, the magneto-optical functional layer adopts a composite structure of ferromagnetic nanorods (Fe3O4 / CoFe2O4) and polymer matrix (PMMA or PDMS). The aspect ratio of the nanorods is precisely controlled in the range of 8:1 to 15:1 (typical value: diameter 200nm / length 1.6-3μm), the filling density is 15-30 vol% (optimized value 25 vol%), and the total thickness of the functional layer covers 10-50μm (standard design 20μm).

[0024] It should be noted that the optical properties of the magneto-optical functional layer follow the magneto-induced birefringence equation: Where B is the applied magnetic field strength (unit: T), θ is the angle between the magnetic field direction and the incident light polarization plane (unit: °), and k is the magneto-optical coefficient of the material (experimental value 0.18 T⁻). 1 ·μm⁻ 1 ).

[0025] According to the magnetostrictive birefringence equation, under a 0.15T magnetic field, when θ rotates from 0° to 45°, Δn increases from 0 to a maximum value of 0.012 (at a wavelength of 550nm), directly inducing a visible spectrum color shift >120nm (e.g., 580nm→460nm), with a dynamic response time <0.2 seconds. Therefore, this method can achieve a magnetic field angle-dependent colorimetric anti-counterfeiting function by modulating the birefringence through nanorod orientation.

[0026] The preparation method described above will be explained in detail below through a specific example.

[0027] Step 1: Fabrication of the magneto-optical functional layer: In this embodiment (1) Preparation of magneto-optical composite materials: Ferromagnetic nanorods (Fe3O4, aspect ratio 10:1, diameter 200 nm, length 2 μm) were mixed with UV-curable epoxy resin (brand name: LOCTITE 3491) at a filling density of 25 vol%. 0.5 wt% dispersant (BYK-111) was added to prevent nanorod aggregation. The mixture was stirred at 2000 rpm for 60 minutes using a high-speed planetary mixer to obtain a homogeneous magneto-optical composite slurry.

[0028] (2) Coating and orientation: The above slurry was applied to a temporary PET release film (50 μm thick) using a slit coater, and the wet film thickness was controlled to be 25 μm.

[0029] The coated film is immediately transferred to a pulsed magnetic field generator. This device generates a magnetic field with an intensity of 0.2 T and a spiral gradient from 0° to 90° with the film plane, lasting for 10 seconds. During this process, the ferromagnetic nanorods are driven by the magnetic field torque and achieve precise orientation along the magnetic field lines.

[0030] (3) Curing and shaping: While maintaining the magnetic field, immediately apply a UV-LED curing lamp (wavelength 365nm, intensity 100 mW / cm²). 2 Irradiate for 5 seconds to allow the epoxy resin to fully cure, permanently fixing the orientation structure of the nanorods and forming a magneto-optical functional layer with a thickness of about 18 μm.

[0031] Step 2: Fabrication of the patterned reflective layer (1) Vacuum evaporation of metal layer: The thin film with magneto-optical functional layer obtained in step 1 is used as a substrate for molding, thereby imprinting a continuous holographic grating covering the entire area on the surface of the magneto-optical functional layer.

[0032] The molded substrate is placed in a vacuum evaporation machine, and the vacuum level is evaporated to 5×10⁻. 3 Pa. Using high-purity aluminum or Ag as the evaporation source, an aluminum film with a thickness of 100 nm is deposited on the surface of the molded structure using electron beam evaporation. This aluminum or Ag film perfectly replicates the underlying holographic structure, with a reflectivity > 90%.

[0033] (2) Micro-etching: A laser micro-engraving system (wavelength 355nm) is used to perform fine ablation on a specific area of ​​the aluminum layer in the overall holographic background. A small portion of the metal is precisely ablated away, and the metal in the ablated area disappears, exposing the transparent magneto-optical material underneath. Finally, micro-text such as "GENUINE" with a line width of 5μm is etched out, forming the final patterned reflective layer.

[0034] Step 3: Multilayer Composite Process The lamination process proceeds from the patterned reflective layer upwards and downwards, laminating the magneto-optical layer and transparent protective layer upwards, and the adhesive layer and substrate layer downwards. In some embodiments: A transparent protective layer is applied over the patterned reflective layer using a flatbed laminator. A 50μm thick transparent PET film is then laminated onto the surface using a 5μm thick UV-curable pressure-sensitive adhesive. The lamination pressure is 0.6 MPa, and the adhesive is fully cured via a UV curing tunnel.

[0035] On the other side of the magneto-optical functional layer (i.e. the side that was initially coated with the temporary PET release film), the same composite process is used to bond a 75μm thick PET base layer.

[0036] (3) Die-cutting and post-processing Using a precision die-cutting machine, the composite material is die-cut into 20mm × 20mm square labels. A 50μm deep serrated anti-transfer structure is simultaneously die-cut into the edge of the label.

[0037] Curing: Place the finished label in a constant temperature environment of 40°C for 24 hours to eliminate internal stress and ensure the long-term stability of the bonding strength between layers and the product performance.

[0038] Example 2 This invention also provides a dynamic anti-counterfeiting label based on the magnetron birefringence effect, which is manufactured using the preparation method for the dynamic anti-counterfeiting label based on the magnetron birefringence effect described in Example 1. Figure 3 As shown, the label includes, from top to bottom, the following layers: a transparent protective layer, a magneto-optical functional layer, a patterned reflective layer, an adhesive layer, and a base layer. The transparent protective layer is used to provide mechanical protection for the label and allow ambient light to pass through; The magneto-optical functional layer comprises oriented ferromagnetic nanorods, which are used to modulate the polarization state and phase of the reflected light from the reflective layer under changes in the direction of an external magnetic field. The patterned reflective layer is configured to carry anti-counterfeiting patterns and reflect light incident on it back to the magneto-optical functional layer. The adhesive layer is used to fix the label to the surface of the object to be affixed; The base layer is used to provide structural strength and stability for the entire label.

[0039] In some embodiments, the top layer is a transparent protective layer, made of highly transparent PET or PMMA film with a thickness of 50-150μm and a light transmittance of >92%, used to provide mechanical support and optical coupling, ensuring the overall flatness of the label and light transmission efficiency.

[0040] The magneto-optical functional layer is the core layer, an independent thin film composed of a core of "ferromagnetic nanorods / polymer composite material" encapsulated by a "transparent encapsulation layer". The core layer is 10-50 μm thick, and the encapsulation layer is a double-sided coated transparent acrylic resin (5-10 μm thick on each side). By controlling the orientation of the nanorods with an external magnetic field, the polarization state and phase of the reflected light are modulated, enabling the dynamic hiding, revealing, and continuous color changing of the pattern.

[0041] The patterned reflective layer serves as an optical information carrier and the first reflective surface, directly supporting microstructures (such as holographic patterns and microtext) and reflecting ambient light.

[0042] The adhesive layer uses a 5-20μm thick UV-cured pressure-sensitive adhesive with a pre-made serrated structure to achieve a firm bond between the label and the object being applied, and also has anti-transfer properties.

[0043] The substrate layer uses a 50-200μm thick PET film, and product information can be printed on the back. It serves as both a printing carrier and a final barrier. The anti-counterfeiting label in this embodiment adopts an integrated structure of "magneto-optical thin film-reflection-protection". By prefabricating the magneto-optical functional layer as an independent thin film and optimizing the interlayer sequence, the problems of nanorod filling, encapsulation, and order control are solved. This structural design ensures a simple optical path ("incident-reflection-modulation-emission"). During use, a specific pattern is hidden at 0° and clearly revealed at 45° through magnetic field control, and dynamically changes color in the 30-60° range. It has advantages such as being uncopyable, dynamically responsive, and low-cost, and is suitable for fields such as product packaging and document anti-counterfeiting, and is easy to mass-produce.

[0044] Please see 4 and Figure 5 , Figure 4 The display shows the dynamic pattern change sequence of the anti-counterfeiting label under magnetic field angles θ of 0° / 45° / 90°; Figure 5The diagram illustrates the response of anti-counterfeiting labels under different magnetic field angles.

[0045] Example 3 This embodiment provides a method for verifying anti-counterfeiting labels, used to verify the dynamic anti-counterfeiting labels based on the magnetron birefringence effect described in the above technical solution, including: Place the permanent magnet near or attach it to the anti-counterfeiting label; Change the angle between the magnetic field direction of the permanent magnet and the normal to the label plane; The dynamic optical response of the pattern on the patterned reflective layer as the included angle changes is observed to verify authenticity.

[0046] In a preferred embodiment, the dynamic optical response of the pattern on the patterned reflective layer as the included angle changes is observed to achieve authenticity verification, including: When the included angle is around 0° or 90°, the pattern disappears or becomes invisible, and when the included angle is around 45°, the pattern becomes clearly visible, proving that the anti-counterfeiting label is genuine.

[0047] As a specific example, when linearly polarized light is incident on a magneto-optical material, under the action of an external magnetic field, the ferromagnetic nanorods in the material will align in a direction along the magnetic field, forming optical anisotropy and producing birefringence.

[0048] The birefringence Δn is closely related to the magnetic field angle θ, specifically manifested as follows: Where B is the magnetic field strength. At 0°, the optical axis is parallel to the polarization direction, resulting in zero birefringence and thus achieving an extinction effect, making the hidden pattern completely invisible. At 45°, the birefringence effect reaches its maximum, and the incident polarized light rotates 90°, producing strong reflection and making the hidden pattern clearly visible. At θ=90°, the optical axis is perpendicular to the polarization direction, the birefringence effect disappears again, and the pattern returns to the extinction state.

[0049] The intensity change of this process strictly follows the physical equations: I = I0·sin 2 (2θ)·sin 2 (πΔnd / λ), where I0 is the incident light intensity, d is the material thickness, and λ is the light wavelength. Therefore, based on this principle, not only can the dynamic display of patterns changing with the magnetic field angle be realized, but also the color effect can be generated through wavelength dependence. Combined with the fast magnetic response characteristics of nanorods (usually completing angle switching within 10-100 milliseconds), it provides a highly secure, uncopyable, and visual dynamic verification method for encryption technology.

[0050] like Figure 6 As shown, Figure 6 The verification results were demonstrated.

[0051] Specifically, due to the simultaneous microtext development effect having a strict threshold response characteristic, the "GENUINE" characters begin to appear clearly within a precise angle range of 30°±5°, with edge sharpness continuously increasing with the angle, achieving an optimal visual contrast of over 80% at 45°.

[0052] In some embodiments, the observation step further includes: identifying holographic diffraction rings or iridescent optical effects that appear at a specific angle.

[0053] The holographic diffraction effect is most pronounced at the 45° trigger point. Specific wavelengths of light undergo constructive interference in the gradient-oriented nanoribbon array, instantly forming an iridescent diffraction ring with a radius of 2.8 mm. The ring-shaped spectral dispersion gradient exhibits a perfect Newtonian color sequence arrangement.

[0054] This rainbow optical signature maintains a peak intensity of approximately 5° across the magnetic field during rotation, allowing even untrained observers to clearly detect the significant shift in optical features by rotating the label. When the angle deviates from the 45° core region, the diffraction efficiency of the holographic ring decreases non-linearly, remaining only faintly visible at 30° and 60° positions.

[0055] This multi-optical response, which strictly corresponds to a specific angle, constitutes the core verification mechanism of the anti-counterfeiting system, enhancing the label's recognizability and dynamic verification function.

[0056] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a dynamic anti-counterfeiting label based on magnetron birefringence effect, characterized in that, include: A magneto-optical functional layer is prepared; the magneto-optical functional layer includes a composite structure of magnetic nanorods and a polymer matrix, which is used to control the spatial orientation of the nanorods through an external magnetic field, modulate the polarization state and phase of the reflected light, and realize a magnetic field angle-dependent color-developing anti-counterfeiting function. A patterned reflective layer is prepared; the patterned reflective layer is used to carry optical information and acts as a reflective surface to reflect ambient light; A multi-layer composite process is used to sequentially stack a transparent protective layer, a magneto-optical functional layer, a patterned reflective layer, an adhesive layer, and a base layer. The transparent protective layer provides mechanical support and optical coupling, ensuring the overall flatness of the label and its light transmission efficiency. The adhesive layer is used to firmly bond the label to the object being labeled. The base layer protects the adhesive layer and provides structural strength for the overall label.

2. The method for preparing a dynamic anti-counterfeiting label based on magnetron birefringence effect according to claim 1, characterized in that, The fabrication of the magneto-optical functional layer includes: Magnetic nanorods and UV-curable polymers are mixed at a preset filling density, and a dispersant is added and stirred evenly to prevent nanorod aggregation, thus obtaining a magneto-optical composite slurry. Magneto-optic composite paste is coated onto a release film, and nanorods are oriented in spatial orientation under the action of a pulsed magnetic field. UV curing and shaping are performed under magnetic field conditions to completely cure the polymer and permanently fix the spatial orientation of the nanorods.

3. The method for preparing a dynamic anti-counterfeiting label based on magnetron birefringence effect according to claim 2, characterized in that, The magnetic nanorods are ferromagnetic nanorods with an aspect ratio of 8:1 to 15:1, a diameter range of 150-250 nm, and a length range of 1.6-3 μm.

4. The method for preparing a dynamic anti-counterfeiting label based on magnetron birefringence effect according to claim 2, characterized in that, The method of controlling the spatial orientation of nanorods through an external magnetic field to modulate the polarization state and phase of reflected light, thereby achieving a magnetic field angle-dependent color-developing anti-counterfeiting function, includes: Based on the magneto-induced birefringence equation, the spatial orientation of the nanorods is adjusted to obtain the corresponding birefringence. By modulating the polarization state and phase of the light reflected by the patterned reflective layer according to the birefringence, the pattern can be dynamically hidden, revealed, and continuously changed in color.

5. The method for preparing a dynamic anti-counterfeiting label based on magnetron birefringence effect according to claim 2, characterized in that, The preparation of the patterned reflective layer includes: Holographic microstructures are molded onto the surface of a release film with a magneto-optical functional layer as a substrate. A metallic reflective layer is deposited on the surface of the molded substrate by vacuum evaporation. Laser micro-engraving technology is used to etch a patterned reflective layer onto the metal reflective layer.

6. The method for preparing a dynamic anti-counterfeiting label based on magnetron birefringence effect according to claim 5, characterized in that, The multilayer composite process includes: A transparent PET film is laminated with UV-cured pressure-sensitive adhesive as a transparent protective layer, and the pressure-sensitive adhesive is cured by UV curing. The same method was used to complete the composite of the magneto-optical functional layer with the patterned reflective layer, the patterned reflective layer with the adhesive layer, and the adhesive layer with the substrate layer. The composite material is die-cut to obtain anti-counterfeiting labels of a preset size.

7. A dynamic anti-counterfeiting label based on magnetron birefringence effect, characterized in that, Made by any of the methods described in claims 1-6, comprising, from top to bottom, the following: a transparent protective layer, a magneto-optical functional layer, a patterned reflective layer, an adhesive layer, and a base layer; The transparent protective layer is used to provide mechanical protection for the label and allow ambient light to pass through; The magneto-optical functional layer comprises oriented ferromagnetic nanorods, which are used to modulate the polarization state and phase of the reflected light from the reflective layer under changes in the direction of an external magnetic field. The patterned reflective layer is configured to carry anti-counterfeiting patterns and reflect light incident on it back to the magneto-optical functional layer. The adhesive layer is used to fix the label to the surface of the object to be affixed; The base layer is used to provide structural strength and stability for the entire label.

8. A method for verifying anti-counterfeiting labels, used to verify the dynamic anti-counterfeiting label based on the magnetron birefringence effect as described in claim 8, characterized in that, include: Place the permanent magnet near or attach it to the anti-counterfeiting label; Change the angle between the magnetic field direction of the permanent magnet and the normal to the label plane; The dynamic optical response of the pattern on the patterned reflective layer as the included angle changes is observed to verify authenticity.

9. The anti-counterfeiting label verification method according to claim 8, characterized in that, To verify authenticity, the dynamic optical response of the pattern on the patterned reflective layer as the included angle changes is observed, including: When the included angle is around 0° or 90°, the pattern disappears or becomes invisible, and when the included angle is around 45°, the pattern becomes clearly visible, proving that the anti-counterfeiting label is genuine.

10. The anti-counterfeiting label according to claim 1, characterized in that, The observation steps also include: identifying holographic diffraction rings or iridescent optical effects that appear at a specific angle.

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