Polarization color changing element and using method and application thereof

Abstract

The invention relates to the technical field of optical materials and elements, in particular to a polarization color changing element and a using method and application thereof. The polarization color changing element at least comprises two dye liquid crystal layers, at least one dye liquid crystal layer is an oriented dichroism dye liquid crystal layer, and delta Eab between different dye liquid crystal layers is larger than or equal to 3.0. By limiting delta Eab between different dye liquid crystal layers of the polarization color changing element to be larger than or equal to 3.0, the visual contrast of color change under polarized light is remarkably improved, and anti-fake features are easier to recognize by naked eyes; a * or b * gt of each dye liquid crystal layer of the polarization color changing element is further defined; and the visible light transmittance T is more than or equal to 10% and less than or equal to 70%, so that the color saturation of each layer is high, the light transmittance is moderate, and the identification difficulty caused by too dark or too bright color under polarized light is avoided.

Description

Technical Field

[0001] This invention relates to the field of optical materials and components, specifically to a polarizing color-changing element and its usage and application. Background Technology

[0002] Polarization-modulated elements, as a class of functional devices that can dynamically change color through polarization of light, have shown broad application prospects in fields such as information encryption, anti-counterfeiting, smart displays, and optical sensing due to their unique optical response characteristics, becoming a research hotspot in the field of optical materials and devices in recent years. With the continuous improvement of device performance requirements in related application scenarios, developing polarization-modulated technology that combines high response sensitivity, wide color control range, good stability, and simple fabrication processes has become a core demand in the industry.

[0003] Currently, the development of polarization-based color-changing technology has formed multiple technical paths. In the field of combining photochromism and polarization, relevant patents have disclosed technical solutions for achieving polarization-responsive color-changing through specific material design. Chinese invention patent CN100416314C discloses a polarization-based photochromic device and its manufacturing method. It introduces thermally reversible photochromic-dichroic compounds containing pyran, oxazine, and other groups into the coating, enabling the device to switch between two states in response to photochemical radiation. However, its color-changing process requires external light stimulation to trigger, rather than being driven by a change in polarization angle.

[0004] Furthermore, significant progress has been made in polarization-modulated color technology based on micro / nano structure control. By constructing special structures such as nanoparticle arrays and wire grids, polarization-dependent color changes can be achieved using the interference and diffraction effects of light. The combination of chiral polymers with electrochromic and mechanosensitive materials has expanded the control methods for polarization-modulated color, enabling dynamic adjustment of the characteristics of circularly polarized light through electric fields and mechanical deformation. However, existing polarization-modulated technologies still face many unresolved issues. Some technologies rely on complex material synthesis processes, such as the cumbersome and costly preparation of chiral templates; some devices have limited color control ranges, making it difficult to achieve full-spectrum dynamic switching; and issues such as insufficient integration of multi-stimulus responses and poor long-term stability also limit their application in high-end scenarios. Therefore, developing a polarization-modulated element that is simple to manufacture, has excellent performance, and is widely applicable is of great significance for promoting technological upgrades and industrial development in related fields. Summary of the Invention

[0005] The first aspect of the present invention provides a polarization color-changing element comprising at least two dye liquid crystal layers, wherein at least one layer is an oriented dichroic dye liquid crystal layer, and the ΔEab between different dye liquid crystal layers is ≥3.0 (ΔEab is a parameter in the standard color space established by the International Commission on Illumination, which is based on the color perception difference in the Lab color space).

[0006] Optionally, the ΔEab between different dye liquid crystal layers is ≥30.

[0007] The polarization-changing color-changing element of this invention comprises at least two dye-liquid crystal layers, wherein at least one is an oriented dichroic dye-liquid crystal layer, and the other dye-liquid crystal layers can be either oriented dichroic dye-liquid crystal layers or ordinary dye-liquid crystal layers. When ΔEab ≥ 3.0 between different dye-liquid crystal layers, the different dye-liquid crystal layers exhibit significant color difference, meaning that different dye-liquid crystal layers have different appearance colors. When the element is observed under a polarized light source, changing the angle between the element and the polarized light reveals a significant color difference in the element's appearance color at different angles; that is, the larger the ΔEab between different dye-liquid crystal layers, the greater the color difference in the element's appearance color at different angles, and the more obvious the contrast.

[0008] The |a*| (red-green axis parameter) or |b*| (yellow-blue axis parameter) of the dye liquid crystal layer is >3.0, and the visible light transmittance of the dye liquid crystal layer is 10-70%.

[0009] In the polarization-changing color-changing element of this invention, the |a*| or |b*| of each dye liquid crystal layer is greater than 3.0, and the visible light transmittance of each dye layer is in the range of 10% ≤ T (transmittance) ≤ 70%. The fact that |a*| or |b*| of each dye liquid crystal layer is greater than 3.0 indicates that the appearance color of each dye liquid crystal layer is a medium-brightness, high-saturation color with a significant color shift, not black, white, or gray. When the element is observed under a polarized light source, changing the angle between the element and the polarized light reveals a significant color difference at different angles, resulting in a clear contrast. For the multilayer stack of dye liquid crystal layers of this invention, when the visible light transmittance of each dye layer is in the range of 10% ≤ T ≤ 70%, it is convenient to observe the appearance color of the element under a polarized light source. Changing the angle between the element and the polarized light reveals a significant color difference at different angles, resulting in a clear contrast.

[0010] The polarization color-changing element includes two dichroic dye liquid crystal layers, each having at least one optical axis direction, and the two dichroic dye liquid crystal layers having regions where the optical axes are perpendicular to each other.

[0011] The polarization color-changing element includes a first alignment layer, a first dichroic dye liquid crystal layer, a second alignment layer, and a second dichroic dye liquid crystal layer stacked in sequence, wherein at least one dichroic dye liquid crystal layer has two regions with mutually perpendicular optical axes, and the two regions with mutually perpendicular optical axes constitute corresponding patterns.

[0012] Optionally, the graphics and text include, but are not limited to, symbols, text, and patterns.

[0013] The first alignment layer and the second alignment layer include a photoalignment layer or a polyimide alignment layer.

[0014] Optionally, the polyimide alignment layer is formed by coating a polyimide precursor-polyamic acid solution, and then imidized at high temperature to form a stable polyimide film. Typically, a cloth roller is used to rub the surface of the polyimide film along a specific direction to create fine grooves, guiding the liquid crystal molecules to align along the groove direction.

[0015] Optionally, the photoalignment layer contains a linear photopolymer material. Through stepwise exposure to linearly polarized ultraviolet light, different orientations are generated in different regions of the photoalignment layer. A liquid crystal prepolymer (LCP) layer is then coated on top of the photoalignment layer. The liquid crystal molecules align along the orientation direction of the photoalignment layer and undergo cross-linking and curing under ultraviolet light to form a birefringent phase retardation layer with optical anisotropy. Hidden information can be observed by viewing the anti-counterfeiting element through a polarizer. Rotating the polarizer or the anti-counterfeiting element causes the hidden information to interchange between positive and negative light. The specific method for forming the hidden information is described in the embodiment section of US Patent US6806930B2.

[0016] The photoalignment layer is composed of a photoalignment material, which is selected from at least one of III-1 to III-15: III-1: Poly[oxy-4-[4-[4-[(E)-2-methoxycarbonyl-vinyl]-phenyl]-phenoxy]-butyl]-]-methyl-methylenesilyl], III-2: Poly[oxy-6-[6-[4-[(E)-2-methoxycarbonyl-vinyl]-phenyl]-cyclohexyloxy]-hexyl]-1-methyl-methylenesilyl], III-3: Poly[oxy-4-[4-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-butyl]-methyl-methylenesilyl-co-oxy-4-[4-[4-[(E)-2-hexyloxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-butyl]- III-4: Poly[oxy-4-[4-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-butyl]-methyl-methylenesilyl-co-oxy-6-[4-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-hexyl]-methyl-methylenesilyl], III-5: Poly[1-[6-[4-[2-methyl-4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-hexyloxycarbonyl]-1-methyl-ethylidene], III-6: Poly[1-[4-[4-[2-methyl-4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-hexyloxycarbonyl]-1-methyl-ethylidene], III-6: Poly[1-[4-[4-[2-methyl-4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-hexyloxycarbonyl]-1-methyl-ethylidene], III-7: Poly[1-[2-[4-[2-methoxy-4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-ethoxycarbonyl]-1-methyl-ethylene], III-8: Poly[1-[3-[4-[2-methoxy-4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-propoxycarbonyl]-1-methyl-ethylene], III-9: Poly[1-[2-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-ethoxy]- [1-[2-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-ethoxycarbonyl]-1-methyl-ethylene-co-1-[2-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-ethoxycarbonyl]-1-methyl-ethylene-co-1-[2-[4-[(E)-2-(2-methyl-butoxy)carbonyl-vinyl]-phenoxy]-ethoxycarbonyl-1-methyl-ethylene-co-1-[2-hydroxy-ethoxycarbonyl]-1-methyl-ethylene], III-10: Poly[1-[2-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-ethoxycarbonyl-1-methyl-ethylene-co-1-[2-hydroxy-ethoxycarbonyl]-1-methyl-ethylene],III-11: Poly[1-[2-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-ethoxycarbonyl]-1-methyl-ethylidene-co-1-[2-[4-[(E)-2-octyloxycarbonyl-vinyl]-phenoxy]-ethoxycarbonyl]-1-methyl-ethylidene-co-1-[2-hydroxy-ethoxycarbonyl]-1-methyl-ethylidene], III-12: Poly[1-[2-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxy]-ethoxycarbonyl]-1-methyl-ethylidene-co-1-[2-[4-[(E)-2-dodecyloxycarbonyl-vinyl]-phenoxy]-ethoxycarbonyl]-1-methyl-ethylidene-co-1-[2-hydroxy-ethoxycarbonyl]-1-methyl-ethylidene], II I-13: Poly[1-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-1-methyl-ethylidene co-1-[4-[(E)-2-hexyloxycarbonyl-vinyl]-phenoxycarbonyl]-1-methyl-ethylidene], III-14: Poly[1-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-1-methyl-ethylidene co-1-[4-[(E)-2-octyloxycarbonyl-vinyl]-phenoxycarbonyl]-1-methyl-ethylidene], III-15: Poly[1-[4-[(E)-2-ethoxycarbonyl-vinyl]-phenoxycarbonyl]-1-methyl-ethylidene co-1-[4-[(E)-2-pentoxycarbonyl-vinyl]-phenoxycarbonyl]-1-methyl-ethylidene].

[0017] The dichroic dye liquid crystal layer is composed of dichroic dyes, nematic liquid crystal materials, organic solvents, and functional additives. The functional additives include at least one of photoinitiators, surfactants, ultraviolet absorbers, antioxidants, leveling agents, crosslinking agents, and antioxidants.

[0018] The nematic liquid crystal material includes, but is not limited to, one of L1 to L11.

[0019] Formula L1; Formula L2; Formula L3; Formula L4; Formula L5; Formula L6; Formula L7; Formula L8; Formula L9; Formula L10; Formula L11.

[0020] The dichroic dye liquid crystal layer contains at least one dichroic dye.

[0021] Optionally, the dichroic dye includes dichroic dyes containing crosslinking functional groups.

[0022] Optionally, the dichroic dye containing crosslinking functional groups is selected from at least one of B-1 to B-16 in Table 1.

[0023] Table 1

[0024] The solvent dyes used in the dye liquid crystal layer include, but are not limited to, CI Solvent Yellow 171, CI Solvent Yellow 184, CI Solvent Yellow 189, CI Solvent Orange 4, CI Solvent Orange 14, CI Solvent Orange 31, CI Solvent Red 127, CI Solvent Red 124, CI Solvent Red 117, CI Solvent Red 160, CI Solvent Red 172, CI Solvent Red 207, CI Solvent Blue 14, CI Solvent Blue 6, CI Solvent Blue 36, CI Solvent Blue 18, CI Solvent Blue 55, CI Solvent Blue 104, and CI Solvent Blue 122.

[0025] Optionally, the functional additives include photoinitiators and leveling agents.

[0026] Optionally, the photoinitiator includes at least one of Irgacure184, Irgacure369, Irgacure907, Irgacure1173, IrgacureTPO, Irgacure819, and IrgacureITX.

[0027] Optionally, the leveling agent includes at least one of BYK-323 and BYK-361.

[0028] Optionally, the antioxidant includes at least one of hindered amines and phenols.

[0029] Optionally, the organic solvent includes at least one selected from butanone, cyclohexanone, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, methyl propyl ketone, cyclopentanone, diisobutyl ketone, dioxane, dioxane, ethylene glycol methyl ether acetate, propylene glycol methyl ether acetate, N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N-methylpropionamide.

[0030] Optionally, the organic solvent is cyclohexanone.

[0031] The polarizing color-changing element also includes a substrate layer, and the materials used in the substrate layer include, but are not limited to, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), triacetyl cellulose (TAC), polypropylene, polycarbonate (PC), polymethyl methacrylate (PMMA), and cyclic olefin copolymer (COP).

[0032] Optionally, the material used for the substrate layer includes an isotropic substrate, including one of TAC, PMMA, and COP.

[0033] The alignment layer and the dye liquid crystal layer (or dichroic dye liquid crystal layer) can be interlayered by coating. The coating method can apply the liquid crystal mixture to the substrate using conventional coating techniques such as spin coating, bar coating, or blade coating. Alternatively, the formulation can be applied to the substrate using conventional printing techniques known to those skilled in the art, such as screen printing, offset printing, roll-to-roll printing, letterpress printing, gravure printing, rotary gravure printing, flexographic printing, engraving gravure printing, pad printing, heat-sealing printing, inkjet printing, or printing with the aid of a printing mold or printing plate.

[0034] The second aspect of the present invention provides a method for using a polarization color-changing element, comprising the following steps: placing the polarization color-changing element on a polarization light source, changing the angle between the polarization color-changing element and the polarization light source (rotating the element or the polarization light source), and the element exhibiting polarization color-changing.

[0035] The polarized light source includes a computer screen or a mobile phone screen.

[0036] The method of use involves placing the component on a polarized light source, such as a linearly polarized light transmission stage, and rotating the component or the polarized light source. The component's appearance color changes significantly. When the optical axis of the oriented dichroic dye liquid crystal layer in the component is aligned with the direction of the polarized light, the polarized light passes through the dichroic dye liquid crystal layer, making the layer nearly transparent. The component's appearance color primarily reflects the colors of the other dye layers. Changing the angle between the component and the polarized light, so that the optical axis of the oriented dichroic dye liquid crystal layer is perpendicular to the direction of the polarized light, the dichroic dye strongly absorbs the polarized light. The dichroic dye liquid crystal layer exhibits a distinct dichroic dye color, and the component's appearance color is a superposition of the colors of the dichroic dye liquid crystal layer and other dye layers. Therefore, changing the angle between the component and the polarized light significantly changes the appearance color of the polarization-changing component. By using a polarizer built into a computer screen or mobile phone screen to emit linearly polarized light, the polarization-changing characteristics of the component can be easily identified.

[0037] A third aspect of this invention provides an application of a polarizing color-changing element for anti-counterfeiting purposes, including banknotes, passports, ID cards, product labels, and pharmaceutical packaging.

[0038] Beneficial effects 1. This invention significantly improves the visual contrast of color changes under polarized light by limiting ΔEab ≥ 3.0 between different dye liquid crystal layers of the polarization color-changing element, making anti-counterfeiting features easier to identify with the naked eye.

[0039] 2. By limiting the |a*| or |b*| of each dye liquid crystal layer of the polarization color-changing element to >3.0 and the visible light transmittance to the range of 10%≤T≤70%, this invention ensures that each layer has high color saturation and moderate light transmittance, thus avoiding recognition difficulties caused by colors that are too dark or too bright under polarized light.

[0040] 3. The optical axes of the two dichroic dye liquid crystal layers of this invention are perpendicular to each other, enabling precise switching between the two colors and enhancing the complexity and uniqueness of the anti-counterfeiting features.

[0041] 4. The optical alignment layer of the present invention forms optical axis directions in different regions to form graphic structures, which can embed variable hidden graphics in the components, achieve high-precision anti-counterfeiting patterns without additional printing, and only appear under specific polarization conditions. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the structure of the polarization color-changing element in Example 1.

[0043] Figure 2 This is a schematic diagram of the structure of the polarization color-changing element in Example 2.

[0044] The structure includes: 1. Substrate; 2. Photoalignment layer; 3. Dichroic dye liquid crystal layer; 4. Colored dye liquid crystal layer; 5. First photoalignment layer; 6. First dichroic dye liquid crystal layer; 7. Second photoalignment layer; 8. Second dichroic dye liquid crystal layer. Detailed Implementation

[0045] Examples 1-4, Comparative Example 1 A polarizing color-changing element, as shown in Table 1 (" / " indicates unused), wherein, as Figure 1 As shown, Example 1 has a four-layer structure, which is stacked sequentially as a substrate layer (TAC) / photoalignment layer / dichroic dye liquid crystal layer / cyan dye liquid crystal layer; as Figure 2As shown, Example 2 has a four-layer structure, which is stacked sequentially as a substrate layer (PMMA) / first photoalignment layer / magenta dichroic dye liquid crystal layer / second photoalignment layer / cyan dichroic dye liquid crystal layer; Example 3 has a six-layer structure, which is stacked sequentially as a substrate layer (PMMA) / first photoalignment layer / magenta dichroic dye liquid crystal layer / adhesive layer / yellow dichroic dye liquid crystal layer / second photoalignment layer; Example 4 has a five-layer structure, which is stacked sequentially as a substrate layer (PMMA) / photoalignment layer / dichroic magenta dye liquid crystal layer / yellow dye liquid crystal layer / blue dye liquid crystal layer; Comparative Example 1 has a four-layer structure, which is stacked sequentially as a substrate layer (TAC) / photoalignment layer / yellow dye liquid crystal layer / blue dye liquid crystal layer.

[0046] Table 1

[0047] The method for preparing the polarization-changing element in one of the embodiments includes the following steps: S1, dissolve the photoalignment material using an organic solvent to obtain an alignment liquid, coat the alignment liquid onto a substrate and dry it, expose the entire photoalignment layer using linearly polarized ultraviolet light to form a unidirectional exposed photoalignment layer; or first expose the first alignment region of the photoalignment layer in a first direction using linearly polarized ultraviolet light through a mask; remove the mask, and expose the photoalignment layer using linearly polarized ultraviolet light perpendicular to the first exposure direction to form a bidirectional exposed photoalignment layer; S2, a polymerizable liquid crystal, a dichroic dye, a photoinitiator, a leveling agent, and an antioxidant are dissolved in an organic solvent to obtain a dichroic dye liquid crystal formulation. The dichroic dye liquid crystal formulation is coated onto the photoalignment layer, and after drying and curing, a dichroic dye liquid crystal layer is formed on the photoalignment layer.

[0048] Comparative Example 1 involves a method for preparing a dye liquid crystal layer, which includes the following steps: A dye liquid crystal formulation is obtained by dissolving polymerizable liquid crystals, dyes, photoinitiators, leveling agents, and antioxidants in an organic solvent. The dye liquid crystal formulation is then coated onto the dichroic dye liquid crystal layer, and after drying and curing, a dye liquid crystal layer is formed. Alternatively, the dye liquid crystal formulation is coated onto another substrate, and after drying and curing, a dye liquid crystal layer is formed. An aqueous adhesive (NeoCryl® A-1127 or NeoCryl® A-1120) is coated onto the dye liquid crystal layer, dried, and then laminated with the dichroic dye liquid crystal layer, thus transferring the dye liquid crystal layer onto the dichroic dye liquid crystal layer.

[0049] For a polarizing color-changing element with a structure of a first alignment layer, a first dichroic dye liquid crystal layer, a second alignment layer, and a second dichroic dye liquid crystal layer, the following steps can be taken: First, the photoalignment liquid 2 can be coated onto the first dichroic dye liquid crystal layer in S2, dried, and exposed in one direction, or a mask can be used for bidirectional exposure. Second, the dichroic dye liquid crystal formulation liquid 2 can be coated onto the second photoalignment layer, dried, and cured to form the second dichroic dye liquid crystal layer. The final polarization element is formed by a structure consisting of a first alignment layer, a first dichroic dye liquid crystal layer, a second alignment layer, and a second dichroic dye liquid crystal layer; or, a second photoalignment layer and a second dichroic dye liquid crystal layer are formed on another substrate according to steps S1 and S2, an adhesive (NeoCryl® A-1127 or NeoCryl® A-1120) is coated on the second dichroic dye liquid crystal layer, dried, and the second dichroic dye liquid crystal layer and the first dichroic dye liquid crystal layer are composited to finally form a polarization element consisting of a first alignment layer, a first dichroic dye liquid crystal layer, a composite adhesive, a second dichroic dye liquid crystal layer, and a second alignment layer.

[0050] The photoalignment layer uses cyclohexanone as a solvent, with a photoalignment material mass concentration of 3% and a photoalignment layer thickness of 90 nm. The dye liquid crystal layer and the dichroic dye liquid crystal layer also use cyclohexanone as a solvent, with a dye liquid crystal or dichroic dye liquid crystal mass concentration of 30% and a thickness of 12 μm. The dye:polymerizable liquid crystal:IrgacureTPO:leveling agent BYK-361:hydroquinone (weight ratio) in the dye liquid crystal layer and the dichroic dye liquid crystal layer is 3:92.5:4:0.3:0.2.

[0051] Performance testing methods and data The polarization color-changing elements in the examples and comparative examples were tested for performance. The test data are listed in Table 2 (" / " indicates that they were not used and no test is required).

[0052] Table 2

Claims

1. A polarizing color-changing element, characterized in that, It includes at least two dye liquid crystal layers, wherein at least one is an oriented dichroic dye liquid crystal layer, and the ΔE between different dye liquid crystal layers is... ab ≥3.

0.

2. The polarizing color-changing element according to claim 1, characterized in that, The |a*| or |b*| of the dye liquid crystal layer is greater than 3.0, and the visible light transmittance of the dye liquid crystal layer is 10-70%.

3. The polarizing color-changing element according to claim 2, characterized in that, The polarization color-changing element includes two dichroic dye liquid crystal layers, each having at least one optical axis direction, and the two dichroic dye liquid crystal layers having regions where the optical axes are perpendicular to each other.

4. The polarizing color-changing element according to claim 3, characterized in that, The polarization color-changing element includes a first alignment layer, a first dichroic dye liquid crystal layer, a second alignment layer, and a second dichroic dye liquid crystal layer stacked in sequence, wherein at least one dichroic dye liquid crystal layer has two regions with mutually perpendicular optical axes, and the two regions with mutually perpendicular optical axes constitute corresponding patterns.

5. The polarizing color-changing element according to claim 4, characterized in that, Both the first alignment layer and the second alignment layer include a photoalignment layer or a polyimide alignment layer.

6. The polarizing color-changing element according to claim 1, characterized in that, The dichroic dye liquid crystal layer contains at least one dichroic dye.

7. A method of using the polarizing color-changing element according to any one of claims 1-6, characterized in that, Includes the following steps: By placing a polarizing color-changing element on a polarizing light source and changing the angle between the element and the light source, the element exhibits polarization color-changing behavior.

8. The method of using the polarizing color-changing element according to claim 7, characterized in that, The polarized light source includes a computer screen or a mobile phone screen.

9. An application of the polarizing color-changing element according to any one of claims 1-6, characterized in that, It is used in the field of anti-counterfeiting of banknotes, passports, ID cards, product labels, and pharmaceutical packaging.

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