CN114958032A

CN114958032A - Photochromic pigment with high color saturation

Info

Publication number: CN114958032A
Application number: CN202110220414.5A
Authority: CN
Inventors: 孙洪保; 孙倩云; 陈章荣; 潘硕
Original assignee: Huizhou Foryou Optical Technology Co ltd
Current assignee: Huizhou Foryou Optical Technology Co ltd
Priority date: 2021-02-26
Filing date: 2021-02-26
Publication date: 2022-08-30

Abstract

The present application provides a photochromic pigment having high color saturation. The high color saturation photochromic pigment comprises: the reflection layer and the dielectric lamination layer are arranged on the main surface of at least one side of the reflection layer, the dielectric lamination layer comprises a first dielectric layer, an absorption layer, a second dielectric layer and a plurality of metal nano-particles which are sequentially arranged in a lamination mode, gaps are formed among the metal nano-particles, and the refractive index of a material of the second dielectric layer is larger than 1.65. The photochromic pigment with high color saturation realizes the optically variable effect of the photochromic pigment with color variation along with angles under natural light by utilizing the interference effect of a film layer and the enhancement effect of metal nano particles on scattered light, and simultaneously, new color change can occur under the irradiation of strong visible light, so that the photochromic pigment has double anti-counterfeiting effects; in addition, the photochromic pigment has a simple structure and good monochromaticity.

Description

Photochromic pigment with high color saturation

Technical Field

The application relates to the technical field of anti-counterfeiting, in particular to a photochromic pigment with high color saturation.

Background

The optically variable anti-counterfeiting technology is based on the optically variable effect of multi-beam interference of an optical multilayer film, under the condition that an incident angle is changed, a reflected light beam changes along with the angle due to the fact that an equivalent optical path changes along with the angle, so that the reflection spectrum shifts, and the color effect changes along with the change of an observation angle to generate the color change effect, and the color change effect cannot be reproduced by common scanning/copying. In recent years, with the progress of the production technology and the continuous improvement of the production process of the optically variable pigment, the application of the optically variable anti-counterfeiting pigment is expanded.

The inventor of the present application finds that the structure of the existing optical color-changing material realizes the optical variable effect, but the effect is single.

Disclosure of Invention

The application provides a photochromic pigment with high color saturation, which aims to solve the technical problem that the effect of the photochromic pigment in the prior art is single.

In order to solve the technical problems, the application adopts a technical scheme that a photochromic pigment with high color saturation is provided, and comprises: the reflection layer and the dielectric lamination layer are arranged on the main surface of at least one side of the reflection layer, the dielectric lamination layer comprises a first dielectric layer, an absorption layer, a second dielectric layer and a plurality of metal nano-particles which are sequentially arranged in a lamination mode, gaps are formed among the metal nano-particles, and the refractive index of a material of the second dielectric layer is larger than 1.65.

Further, the two sides of the reflecting layer opposite to each other are symmetrically provided with the dielectric lamination layer.

Further, the reflective layer has a thickness in the range of 5 to 200 nm.

Further, the material of the reflective layer includes: one or an alloy of at least two of aluminum, silver, copper, gold, platinum, tin, titanium, palladium, nickel, cobalt, rhodium, niobium, chromium.

Further, the thickness of the absorption layer ranges from 3 to 30 nm.

Further, the material of the absorption layer includes: one or an alloy of at least two of titanium, aluminum, chromium, nickel, palladium, titanium, vanadium, cobalt, iron, carbon, tin, tungsten, molybdenum, rhodium, niobium.

Further, the refractive index of the material of the first dielectric layer is less than or equal to 1.65.

Further, the material of the first dielectric layer comprises: silicon dioxide, aluminum oxide, magnesium fluoride, aluminum fluoride, cerium fluoride, lanthanum fluoride, neodymium fluoride, samarium fluoride, barium fluoride, calcium fluoride, lithium fluoride polystyrene, polyethylene, polymethyl methacrylate, polyamideimide, polyperfluoroethylpropylene, tetrafluoroethylene, chlorotrifluoroethylene, cellulose propionate, cellulose acetate butyrate, methylpentene polymer, homopolyformaldehyde, acrylic resin, cellulose nitrate, ethyl cellulose, polypropylene, polysulfone, polyethersulfone, mica, a heteroisomorphous polymer, polybutene, an ionomer, an acrylic copolymer, a thermoplastic, styrene butadiene, polyvinyl chloride, urea formaldehyde, styrene acrylonitrile, polycarbonate.

Further, the material of the second dielectric layer comprises: lanthanum titanate, titanium oxide, niobium pentoxide, zinc sulfide, zinc oxide, zirconium oxide, titanium dioxide, carbon, indium oxide, indium tin oxide, tantalum pentoxide, cerium oxide, yttrium oxide, europium oxide, iron oxide, triiron tetroxide, hafnium nitride, hafnium carbide, hafnium oxide, lanthanum oxide, magnesium oxide, neodymium oxide, praseodymium oxide, samarium oxide, antimony trioxide, silicon carbide, silicon nitride, silicon monoxide, selenium trioxide, tin oxide, and tungsten trioxide.

Furthermore, the physical thickness of the first dielectric layer is 10-800nm, and the physical thickness of the second dielectric layer is 10-800 nm.

Further, the first medium layer and/or the second medium layer comprise at least one high refractive index layer and at least one low refractive index layer, wherein the high refractive index layer and the low refractive index layer are alternately arranged in sequence.

Further, the material of the metal nanoparticles includes: at least one of aluminum, silver, gold, copper, platinum, ruthenium, palladium, rhodium, cobalt, iron, nickel, lead, osmium, and iridium, or an alloy of at least two thereof.

Furthermore, a plurality of metal nano-particles are arranged at intervals, and the gap between every two adjacent metal nano-particles is 2nm-1 mm.

Further, the size of the metal nanoparticles is 5nm to 1 μm.

Further, the shape of the metal nanoparticles is spherical, hemispherical, ellipsoidal, cubic, rectangular, octahedral, dodecahedral, hexadecahedral, cylindrical, star-shaped, pyramidal, triangular or cylindrical.

Further, the photochromic pigment also comprises a protective layer covering the surface of the metal nano-particles.

Further, the material of the protective layer includes: polystyrene, polyethylene, polymethyl methacrylate, polyamideimide, polyperfluoroethylpropylene, tetrafluoroethylene, chlorotrifluoroethylene, cellulose propionate, cellulose acetate butyrate, methylpentene polymer, homopolyformaldehyde, acrylic resin, cellulose nitrate, ethylcellulose, polypropylene, polysulfone, polyethersulfone, mica, heteroisomorphous polymer, polybutene, ionomer, acrylic copolymer, thermoplastic, styrene butadiene, polyvinyl chloride, urea formaldehyde, styrene acrylonitrile, polycarbonate, silica, alumina, magnesium fluoride, aluminum fluoride, cerium fluoride, lanthanum fluoride, neodymium fluoride, samarium fluoride, barium fluoride, calcium fluoride, and lithium fluoride.

The beneficial effects of the embodiment of the application are that: different from the situation of the prior art, the photochromic pigment with high color saturation realizes the optically variable effect of the photochromic pigment with the color variation along with the angle under natural light by utilizing the interference effect of a film layer and the enhancement effect of the metal nano particles on scattered light, and simultaneously has the characteristic of strong light variable structure color of new color variation under the irradiation of strong visible light, so that the photochromic pigment has double anti-counterfeiting effect; in addition, the photochromic pigment with high color saturation has a simple structure and good monochromaticity.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic structural view of one embodiment of a highly color saturated photochromic pigment provided herein;

FIG. 2 is a schematic structural view of another embodiment of a highly color saturated photochromic pigment provided herein;

FIG. 3 is a schematic structural view of another embodiment of a highly saturated photochromic pigment provided herein;

FIG. 4 is a schematic flow chart diagram of one embodiment of a process for preparing highly saturated photochromic pigments provided herein;

FIG. 5 is a schematic flow chart diagram of another embodiment of a process for preparing highly saturated photochromic pigments provided herein;

FIG. 6 is a schematic flow chart diagram of another embodiment of a process for preparing highly saturated photochromic pigments provided herein;

FIG. 7 is a schematic flow chart diagram of another embodiment of a process for preparing highly saturated photochromic pigments as provided herein.

Detailed Description

The present application will now be described in detail with reference to specific embodiments thereof as illustrated in the accompanying drawings. These embodiments are not intended to limit the present application, and structural, methodological, or functional changes made by those skilled in the art according to these embodiments are included in the scope of the present application.

In addition, if there is a description of "first", "second", etc. in the embodiments of the present application, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present application.

Referring to fig. 1, fig. 1 is a schematic structural diagram of an embodiment of a photochromic pigment with high color saturation provided by the present application, wherein the photochromic pigment with high color saturation comprises: a reflective layer 11 and a dielectric stack 12, wherein the dielectric stack 12 is disposed on at least one major surface of the reflective layer 11.

In the embodiment shown in fig. 1, the dielectric stack 12 is provided on the main surface on the side of the reflective layer 11. The dielectric stack 12 includes a first dielectric layer 121, an absorption layer 122, a second dielectric layer 123 and a plurality of metal nanoparticles 124, which are sequentially stacked. The first dielectric layer 121 is located between the reflective layer 11 and the absorption layer 122. The photochromic pigment has simple integral structure and convenient manufacture.

Gaps are formed between the metal nanoparticles 124, for example, the metal nanoparticles 124 are spaced apart from each other to expose the bottom film layer. The refractive index of the second dielectric layer 123 is greater than 1.65, for example, the refractive index of the material of the second dielectric layer 123 is 1.7, 1.8, or 1.9, and the like, that is, the material of the second dielectric layer 123 may be a material with a high refractive index.

The photochromic pigment provided by the application has the optically variable effect of changing color along with the angle under natural light and has different color changes under strong light irradiation by utilizing the interference effect of the film layer and the enhancement effect of the metal nano particles 124 on scattered light, so that the photochromic pigment has double anti-counterfeiting effects, better anti-counterfeiting effect and higher counterfeiting difficulty; in addition, the photochromic pigment has a simple overall structure and good monochromaticity. The photochromic pigment with high color saturation can be prepared into pigments and films, and has a wide application range.

It should be noted that the photochromic pigment of the present application can realize color change under high intensity visible light, such as mobile phone light, which is mainly characterized in that the metal nanoparticles 124 have enhanced light scattering to the selective wavelength of the incident light under the action of high light, and the phenomenon is caused by a localized surface plasmon resonance phenomenon. The localized surface plasmon resonance is an optical phenomenon in which the metal nanoparticles 124 with a size smaller than the wavelength of light absorb light waves, and means that under the irradiation of incident light, electron clouds in the metal nanoparticles 124 are redistributed to generate polarization, thereby generating positive and negative electron clouds. When the polarization direction of incident light is parallel to the connection direction of the two metal nanoparticles 124, the positive and negative electronic cloud terminals are respectively distributed at the left and right ends of the metal nanoparticles 124, and the heterogeneous charges enriched on the particle surfaces at the two sides of the gap generate a strong electromagnetic field, which is called as a "hot spot". The 'hot spot' area has strong light scattering enhancement effect on incident light, and a scattering spectrum has certain peaks and troughs, so that the color of the material observed by naked eyes is changed under high-intensity illumination. Since the light scattered by the material is primarily visible to the naked eye under high light, the color change can be seen without looking for a specific viewing angle.

In other embodiments, as shown in fig. 2, fig. 2 is a schematic structural diagram of another embodiment of the photochromic pigment with high color saturation provided in the present application, in this embodiment, the photochromic pigment is disposed in a symmetrical structure, for example, the dielectric stack 12 may be symmetrically disposed on two main surfaces of the reflective layer 11 opposite to each other. The effects of the above embodiments can be achieved with both opposing sides of the photochromic pigment.

Alternatively, the thickness of the reflective layer 11 is in the range of 5-200nm, for example, the thickness of the reflective layer 11 may be 5nm, 10nm, 20nm, 30nm, 40nm, 50nm, 80nm, 90nm, 100nm, 110nm, 140nm, 150nm, or the like.

The material of the reflective layer 11 may include one of aluminum, silver, copper, gold, platinum, tin, titanium, palladium, nickel, cobalt, rhodium, niobium, chromium, or an alloy of at least two of these materials.

The absorber layer 122 has a thickness in the range of 3-30 nm. For example, the thickness of the absorption layer 122 may be 3nm, 5nm, 10nm, 15nm, 20nm, 25nm, or 30nm, etc. The material of the absorption layer 122 may include: one or an alloy of at least two of titanium, aluminum, chromium, nickel, palladium, titanium, vanadium, cobalt, iron, carbon, tin, tungsten, molybdenum, rhodium, niobium.

Optionally, the refractive index of the material of the first dielectric layer 121 is less than or equal to 1.65, for example, the refractive index of the material of the first dielectric layer 121 is 1.1, 1.3, 1.6, 1.65, and the like. The refractive index of the material of the first dielectric layer 121 is smaller than that of the material of the second dielectric layer 123, and in this way, the color change effect of the photochromic pigment can be improved, so that the pigment has better monochromaticity.

When the first dielectric layer 121 is a low refractive index layer, the materials of the first dielectric layer 121 include: silicon dioxide, aluminum oxide, magnesium fluoride, aluminum fluoride, cerium fluoride, lanthanum fluoride, neodymium fluoride, samarium fluoride, barium fluoride, calcium fluoride, lithium fluoride polystyrene, polyethylene, polymethyl methacrylate, polyamideimide, polyperfluoroethylpropylene, tetrafluoroethylene, chlorotrifluoroethylene, cellulose propionate, cellulose acetate butyrate, methylpentene polymer, homopolyformaldehyde, acrylic resin, cellulose nitrate, ethyl cellulose, polypropylene, polysulfone, polyethersulfone, mica, a heteroisomorphous polymer, polybutene, an ionomer, an acrylic copolymer, a thermoplastic, styrene butadiene, polyvinyl chloride, urea formaldehyde, styrene acrylonitrile, polycarbonate.

In other embodiments, the refractive index of the first medium layer 121 may be greater than 1.65, which also enables the photochromic pigment to have a light-variable effect. When the first dielectric layer 121 is also a high refractive index layer, the material of the first dielectric layer 121 may be the same as that of the second dielectric layer 123, and in other embodiments, the material of the first dielectric layer 121 may also be different from that of the second dielectric layer 123.

The physical thickness of the first dielectric layer 121 is 10-800nm, for example, the physical thickness of the first dielectric layer 121 may be 10nm, 50nm, 100nm, 200nm, 250nm, 300nm, 400nm, 500nm, 550nm, 600nm, 700nm, 800nm, or the like.

The physical thickness of the second dielectric layer 123 is 10-800nm, for example, the physical thickness of the second dielectric layer 123 may be 10nm, 50nm, 100nm, 200nm, 250nm, 300nm, 400nm, 500nm, 550nm, 600nm, 700nm, 800nm, or the like.

Alternatively, the second dielectric layer 123 may have a single-layer structure, for example, the second dielectric layer 123 may have only one high refractive index layer structure; in other embodiments, the second medium layer 123 may include at least one high refractive index layer and at least one low refractive index layer, wherein the high refractive index layer and the low refractive index layer are alternately arranged in sequence, that is, the second medium layer 123 may be formed by alternately stacking a plurality of high refractive index layers and low refractive index layers to achieve a specific refractive index.

Alternatively, the first dielectric layer 121 may also be a single-layer structure, for example, the first dielectric layer 121 may be only a low refractive index layer structure; in other embodiments, the first medium layer 121 may include at least one high refractive index layer and at least one low refractive index layer, wherein the high refractive index layer and the low refractive index layer are alternately disposed in sequence, i.e., the first medium layer 121 may be disposed by alternately stacking a plurality of high refractive index layers and low refractive index layers to achieve a certain refractive index.

Several metal nanoparticles 124 in the present application are spaced apart from one another. Specifically, the gap between two adjacent metal nanoparticles 124 is 2nm to 1mm, for example, the gap between two adjacent metal nanoparticles 124 is 2nm, 100nm, 1000nm, 10000nm, 0.1mm, or 1mm, and the like.

Also, the material of the metal nanoparticles 124 is at least one or an alloy of at least two of aluminum, silver, gold, copper, platinum, ruthenium, palladium, rhodium, cobalt, iron, nickel, lead, osmium, and iridium.

The shape of the metal nanoparticles 124 can be any shape, such as spheres, hemispheres, ellipsoids, cubes, cuboids, octahedrons, dodecahedrons, hexadecahedrons, cylinders, stars, pyramids, triangles, cylinders, and other irregular shapes, and the like. The size of the metal nanoparticles 124 is 5nm to 1 μm, such as 5nm, 10nm, 50nm, 100nm, 500nm, or 1 μm, and the like.

It is understood that the shapes of the metal nanoparticles 124 may be uniform, such as being all spherical or all hemispheres. In other embodiments, the metal nanoparticles 124 may also be a mixture of shapes, and may be selected according to actual situations, and is not limited in this respect.

As shown in fig. 3, fig. 3 is a schematic structural diagram of another embodiment of the photochromic pigment with high color saturation provided in the present application, and in this embodiment, in order to protect the metal nanoparticles 124, the photochromic pigment further includes a protective layer 13 covering the surface of the metal nanoparticles 124, different from the above embodiment.

Specifically, the material of the protective layer 13 includes: polystyrene, polyethylene, polymethyl methacrylate, polyamideimide, polyperfluoroethylpropylene, tetrafluoroethylene, chlorotrifluoroethylene, cellulose propionate, cellulose acetate butyrate, methylpentene polymer, homopolyformaldehyde, acrylic resin, cellulose nitrate, ethylcellulose, polypropylene, polysulfone, polyethersulfone, mica, heteroisomorphous polymer, polybutene, ionomer, acrylic copolymer, thermoplastic, styrene butadiene, polyvinyl chloride, urea formaldehyde, styrene acrylonitrile, polycarbonate, silica, alumina, magnesium fluoride, aluminum fluoride, cerium fluoride, lanthanum fluoride, neodymium fluoride, samarium fluoride, barium fluoride, calcium fluoride, and lithium fluoride.

The protective layer 13 can effectively protect the bottom metal nanoparticles 124 and the film structure, thereby improving the reliability of the photochromic pigment.

To sum up, the photochromic pigment that this application provided realizes that this photochromic pigment has the photochromic effect of angle following heterochrosis under the natural light through the interference effect that utilizes the rete and the reinforcing effect of metal nanoparticle 124 to the scattered light, and simultaneously under strong visible light shines, new colour change will also appear to make this photochromic pigment have dual anti-fake effect, in addition, the photochromic pigment's of this application simple structure, and have better monochromaticity.

The photochromic pigment can be prepared into pigment and film, and the film can be directly plated and also can be obtained by transfer printing.

Further, the above photochromic pigment can be prepared by physical vapor deposition, chemical vapor deposition, sol-gel, dipping method, etc.

In one specific embodiment, as shown in FIG. 4, the process for preparing the highly color saturated photochromic pigment comprises:

s11: a substrate layer is provided.

Specifically, the substrate layer may be a rigid substrate or a flexible substrate, for example, the material of the substrate layer may be quartz glass or PET (Polyethylene terephthalate).

S12: an isolation layer is formed on the base layer.

The isolation layer functions to isolate the substrate layer from the photochromic pigment so that the photochromic pigment falls off from the substrate layer.

S13: and depositing metal nanoparticles, a second dielectric layer, an absorption layer, a first dielectric layer, a reflection layer, a first dielectric layer, an absorption layer, a second dielectric layer and metal nanoparticles on the isolation layer in sequence.

Specifically, on the substrate layer, the isolation layer, the metal nanoparticles, the second dielectric layer, the absorption layer, the first dielectric layer, the reflection layer, the first dielectric layer, the absorption layer, the second dielectric layer, and the metal nanoparticles are periodically evaporated and plated for 20 to 30 times or more.

Please refer to the description of the above embodiments for the structure of the first dielectric layer and the second dielectric layer, which is not described herein again.

S14: the photochromic pigment is peeled off from the release layer.

And finally, stripping the photochromic pigment from the isolation layer after repeated evaporation for many times, wherein the stripping mode can adopt a dry method or a wet method.

In another embodiment, as shown in FIG. 5, the process for preparing the highly color saturated photochromic pigment comprises:

s21: a substrate layer is provided.

S22: an isolation layer is formed on the base layer.

S23: sequentially depositing on the isolating layer: the light-emitting diode comprises metal nanoparticles, a first high-refractive-index material layer, a first low-refractive-index material layer, an absorption layer, a second low-refractive-index material layer, a reflection layer, a third low-refractive-index material layer, an absorption layer, a fourth low-refractive-index material layer, a second high-refractive-index material layer and metal nanoparticles.

In this embodiment, a second dielectric layer is formed by stacking a first high refractive index material layer and a first low refractive index material layer, a second low refractive index material layer is used as the first dielectric layer, a third low refractive index material layer is used as the first dielectric layer, and a fourth low refractive index material layer and a second high refractive index material layer are stacked to form the second dielectric layer.

And (3) repeatedly evaporating for 20 to 30 times or more by taking the isolating layer, the metal nanoparticles, the first high-refractive-index material, the first low-refractive-index material layer, the absorbing layer, the second low-refractive-index material layer, the reflecting layer, the third low-refractive-index material layer, the absorbing layer, the fourth low-refractive-index material layer, the second high-refractive-index material layer and the metal nanoparticles as a cycle on the substrate layer.

S24: the photochromic pigment is peeled off from the release layer.

In another embodiment, as shown in FIG. 6, a method of making a high color saturation photochromic pigment includes:

s31: a substrate layer is provided.

Using a roll coater, a substrate layer is provided, specifically, the substrate layer may be a flexible substrate, for example, the material of the substrate layer may be PET (Polyethylene terephthalate).

S32: an isolation layer is formed on the base layer.

S33: and depositing a reflecting layer, a first dielectric layer, an absorbing layer, a second dielectric layer and metal nano-particles on the isolating layer in sequence.

S34: the photochromic pigment is peeled off from the release layer.

The specific stripping mode can adopt a dry method or a wet method, transfer printing or sticking stripping by using an adhesive substrate.

In another embodiment, as shown in FIG. 7, a method of making a high color saturation photochromic pigment includes:

s41: a substrate layer is provided.

The substrate layer is provided using a roll coater, and in particular, the substrate layer may be a flexible substrate, for example, the material of the substrate layer may be PET (Polyethylene terephthalate).

S42: an isolation layer is formed on the base layer.

S43: and depositing a second dielectric layer, an absorption layer, a first dielectric layer, a reflection layer, a first dielectric layer, an absorption layer and a second dielectric layer on the isolation layer in sequence.

S44: the film layer is peeled from the release layer.

S45: the growth of metal nanoparticles on the membrane layer is performed using chemical means.

In summary, the preparation method of the photochromic pigment provided by the application is simple to operate and convenient to produce, improves the production efficiency and reduces the production cost.

It should be understood that although the specification describes embodiments, not every embodiment includes only a single embodiment, and such description is for clarity purposes only, and it will be understood by those skilled in the art that the specification as a whole and the embodiments may be combined as appropriate to form other embodiments as would be understood by those skilled in the art.

The above-listed detailed description is only a specific description of possible embodiments of the present application and is not intended to limit the scope of the present application, and equivalent embodiments or modifications made without departing from the technical spirit of the present application should be included in the scope of the present application.

Claims

1. A photochromic pigment of high color saturation, the photochromic pigment comprising:

a reflective layer;

the dielectric lamination is arranged on the main surface of at least one side of the reflecting layer and comprises a first dielectric layer, an absorption layer, a second dielectric layer and a plurality of metal nano-particles which are sequentially stacked, gaps are formed among the metal nano-particles, and the refractive index of the material of the second dielectric layer is larger than 1.65.

2. Photochromic pigment according to claim 1, characterized in that the two sides of the reflective layer opposite to each other are symmetrically provided with the dielectric stack.

3. Photochromic pigment according to any of claims 1 to 2, characterized in that the thickness of the reflective layer ranges from 5 to 200 nm.

4. Photochromic pigment according to any one of claims 1 to 2, characterized in that the material of the reflective layer comprises: one or an alloy of at least two of aluminum, silver, copper, gold, platinum, tin, titanium, palladium, nickel, cobalt, rhodium, niobium, chromium.

5. Photochromic pigment according to any of claims 1 to 2, characterized in that the thickness of the absorbing layer ranges from 3 to 30 nm.

6. Photochromic pigment according to any one of claims 1 to 2, characterized in that the material of the absorbing layer comprises: one or an alloy of at least two of titanium, aluminum, chromium, nickel, palladium, titanium, vanadium, cobalt, iron, carbon, tin, tungsten, molybdenum, rhodium, niobium.

7. The photochromic pigment of claim 1, wherein the refractive index of the material of the first dielectric layer is less than or equal to 1.65.

8. The photochromic pigment of claim 7, wherein the material of the first dielectric layer comprises: silicon dioxide, aluminum oxide, magnesium fluoride, aluminum fluoride, cerium fluoride, lanthanum fluoride, neodymium fluoride, samarium fluoride, barium fluoride, calcium fluoride, lithium fluoride polystyrene, polyethylene, polymethyl methacrylate, polyamideimide, polyperfluoroethylpropylene, tetrafluoroethylene, chlorotrifluoroethylene, cellulose propionate, cellulose acetate butyrate, methylpentene polymer, homopolyformaldehyde, acrylic resin, cellulose nitrate, ethyl cellulose, polypropylene, polysulfone, polyethersulfone, mica, a heteroisomorphous polymer, polybutene, an ionomer, an acrylic copolymer, a thermoplastic, styrene butadiene, polyvinyl chloride, urea formaldehyde, styrene acrylonitrile, polycarbonate.

9. The photochromic pigment of claim 1, wherein the material of the second dielectric layer comprises: lanthanum titanate, titanium oxide, niobium pentoxide, zinc sulfide, zinc oxide, zirconium oxide, titanium dioxide, carbon, indium oxide, indium tin oxide, tantalum pentoxide, cerium oxide, yttrium oxide, europium oxide, iron oxide, triiron tetroxide, hafnium nitride, hafnium carbide, hafnium oxide, lanthanum oxide, magnesium oxide, neodymium oxide, praseodymium oxide, samarium oxide, antimony trioxide, silicon carbide, silicon nitride, silicon monoxide, selenium trioxide, tin oxide, and tungsten trioxide.

10. The photochromic pigment of claim 1, wherein the physical thickness of the first dielectric layer is 10-800nm and the physical thickness of the second dielectric layer is 10-800 nm.

11. The photochromic pigment of claim 1, wherein the first dielectric layer and/or the second dielectric layer comprises at least one high refractive index layer and at least one low refractive index layer, wherein the high refractive index layer and the low refractive index layer are alternately arranged in sequence.

12. The photochromic pigment of claim 1, wherein the material of the metal nanoparticles comprises: at least one of aluminum, silver, gold, copper, platinum, ruthenium, palladium, rhodium, cobalt, iron, nickel, lead, osmium, and iridium, or an alloy of at least two thereof.

13. The photochromic pigment of claim 12, wherein the plurality of metal nanoparticles are spaced apart from each other, and the gap between two adjacent metal nanoparticles is 2nm to 1 mm.

14. The photochromic pigment of claim 12 wherein the metal nanoparticles are between 5nm and 1 μm in size.

15. The photochromic pigment of claim 1 wherein the shape of the metal nanoparticle is spherical, hemispherical, ellipsoidal, cubic, rectangular, octahedral, dodecahedral, hexadecahedral, cylindrical, star-shaped, pyramidal, triangular or cylindrical.

16. The photochromic pigment of claim 1, further comprising a protective layer covering the surface of the metal nanoparticles.

17. The photochromic pigment of claim 16 wherein the material of the protective layer comprises: polystyrene, polyethylene, polymethyl methacrylate, polyamideimide, polyperfluoroethylpropylene, tetrafluoroethylene, chlorotrifluoroethylene, cellulose propionate, cellulose acetate butyrate, methylpentene polymer, homopolyformaldehyde, acrylic resin, cellulose nitrate, ethylcellulose, polypropylene, polysulfone, polyethersulfone, mica, heteroisomorphous polymer, polybutene, ionomer, acrylic copolymer, thermoplastic, styrene butadiene, polyvinyl chloride, urea formaldehyde, styrene acrylonitrile, polycarbonate, silica, alumina, magnesium fluoride, aluminum fluoride, cerium fluoride, lanthanum fluoride, neodymium fluoride, samarium fluoride, barium fluoride, calcium fluoride, and lithium fluoride.