阅读说明：本技术 吸收干涉型的全介质结构色薄膜 (Absorption interference type all-dielectric structure color film ) 是由 卜轶坤 王雨思 陈楠 刘晋彤 李青原 冯坤 陈昊 于 2020-05-21 设计创作，主要内容包括：本发明公开了吸收干涉型的全介质结构色薄膜,包括干涉薄膜,该干涉薄膜包括吸收型介质材料层和可见光波段透明介质材料层,该吸收型介质材料层在可见光谱380nm-760nm波段的折射率为1.8～4,消光系数为0.01-2,该可见光波段透明介质材料层折射率小于1.7。它具有如下优点：它构成反射式高饱和度薄膜结构色,具有极佳色彩饱和度、随角异色、环境友好特性,且无需复杂光刻工艺。(The invention discloses an absorption interference type all-dielectric structural color film which comprises an interference film, wherein the interference film comprises an absorption type dielectric material layer and a visible light waveband transparent dielectric material layer, the refractive index of the absorption type dielectric material layer in the visible light spectrum 380nm-760nm waveband is 1.8-4, the extinction coefficient is 0.01-2, and the refractive index of the visible light waveband transparent dielectric material layer is less than 1.7. It has the following advantages: the reflective high-saturation thin film structure color has the characteristics of excellent color saturation, angle dependent color and environmental friendliness, and does not need a complex photoetching process.)

1. Absorption interference type's all dielectric structure look film, its characterized in that: the interference film comprises an absorption type medium material layer and a visible light waveband transparent medium material layer, the refractive index of the absorption type medium material layer in a visible spectrum waveband of 380nm-760nm is 1.8-4, the extinction coefficient is 0.01-2, and the refractive index of the visible light waveband transparent medium material layer is smaller than 1.7.

2. The absorbing interference type all-dielectric structural color film according to claim 1, wherein: the refractive index of the transparent medium material layer in the visible light band is 1.3-1.7.

3. The absorbing interference type all-dielectric structural color film according to claim 1, wherein: the difference between the refractive index of the absorption type medium material layer and the refractive index of the visible light wave band transparent medium material layer is more than or equal to 0.2.

4. The absorbing interference type all-dielectric structural color film according to claim 1, 2 or 3, wherein: the transparent dielectric material comprises a plurality of absorption type dielectric material layers and a plurality of visible light wave band transparent dielectric material layers, wherein the absorption type dielectric material layers and the visible light wave band transparent dielectric material layers are alternately laminated.

5. The absorbing interference type all-dielectric structural color film according to claim 1, 2 or 3, wherein: the absorption type dielectric material layer is made of one or a mixture of at least two of vanadium oxide, chromium oxide, cobalt oxide, aluminum nitride, titanium nitride, tin oxide, indium tin oxide, ferroferric oxide, iron oxide, titanium oxynitride, nickel oxide, copper oxide, or sub-oxides corresponding to titanium oxide, tantalum oxide and niobium oxide.

6. The absorbing interference type all-dielectric structural color film according to claim 1, 2 or 3, wherein: the visible light wave band transparent medium material layer is made of one of silicon dioxide, aluminum oxide or metal fluoride or a mixture of at least two of the materials.

7. The absorbing interference type all-dielectric structural color film according to claim 1, 2 or 3, wherein: the visible light wave band transparent medium material layer is made of organic monomer or polymer.

8. The absorbing interference type all-dielectric structural color film according to claim 1, 2 or 3, wherein: also included is a substrate on which the interference film is laminated.

9. The absorbing interference type all-dielectric structural color film according to claim 8, wherein: the substrate is made of one of stainless steel, glass, polyethylene terephthalate, cellulose triacetate, polymethyl methacrylate, polycarbonate, polymethyl methacrylate composite material, polyimide, polypropylene, polyvinyl chloride, polyvinyl butyral, ethylene-vinyl acetate copolymer, polyurethane elastomer, polytetrafluoroethylene, fluoroethylpropylene or polyvinylidene fluoride.

10. Absorption interference type's all dielectric structure look film, its characterized in that: the interference film comprises a plurality of absorption type medium material layers and a plurality of visible light waveband transparent medium material layers which are alternately stacked, the low-refraction medium layer has the full-transparency performance of the visible light waveband, the high-refraction medium layer has the selective absorption function of the visible light waveband, and the number of the optical film layers is set between 3 and 30.

Technical Field

The invention relates to the technical field of structural color films, in particular to an absorption interference type all-dielectric structural color film.

Background

Many living organisms in nature produce gorgeous colors such as butterfly wings, coccinella septempunctata, bee and bird feathers, and gorgeous opals, shells, etc. In principle, this type of color is called physical color, which is different from chemical color of dye (color caused mainly by absorption of light by pigment), and physical color refers to color formed by reflection, scattering, interference or diffraction of light generated in the microstructure of organism, and is also called structural color. The structural color has the advantages of fastness, environmental protection, angle-dependent color variation and the like, so the method has wide application prospect in the fields of display, decoration, anti-counterfeiting and the like.

The light interference effect based on the one-dimensional photonic crystal multilayer film is a main technical method for realizing structural color development in physical color, is also a preferred scheme for realizing structural color in the industrial field at present, and particularly relates to a special structural color effect pigment with a metal scintillation effect and an optical color change effect, which is widely applied in many fields. For example, they are used in color paints, printing inks, liquid inks, plastics, glass, ceramic products and decorative cosmetic formulations. They are also used for the production of security documents and documents, such as bank notes, cheques, bank cards, credit cards, entry cards and entrance tickets, because of their non-reproducible optical effect.

With conventional pigments, a color impression is produced simply by absorption of the specific wavelength of the incident light and diffuse reflection. Common metallic effect pigments are highly reflective of incident light and produce bright colors, but do not produce any color change effects. The structural color film based on the optical interference effect utilizes the alternate combination of high-refractive index films and low-refractive index films to present the interference effect based on the multi-beam interference principle. Under the condition of changing the incident angle, the transmitted or reflected light beam changes with the angle due to the equivalent optical path of the film stack sequence, so that the reflected or transmitted spectrum shifts, and the film presents different structural colors. The structural color has no base material, all the layered structures are formed by overlapping nano-scale films, the multi-layer film structure forms strong interference structural color and high gloss effect, obvious dynamic color change and metal gloss can be realized, and the effect of color change among different reflection angles is called as angle-dependent heterochromatic effect.

However, in certain aspects, the optical interference structured color films known in the prior art have significant disadvantages, as described in detail below.

1. The color rendering property of the all-dielectric transparent film material is poor.

The all-dielectric film material has higher chemical and mechanical stability and can provide an obvious effect of color variation along with angles. Meanwhile, the prepared material can meet the requirements of reflection and transmission. However, since the all-dielectric transparent film material itself is all transparent in the visible light band, and the color saturation angle of the single all-dielectric structural color film is low, it is usually coated on the black bottom to have a good color rendering effect, in order to obtain a high enough spectral purity, a large number of film stacks are required to be superimposed, and a high tuning ratio film layer structure is adopted to compress the reflection bandwidth, which inevitably increases the number of material layers and the physical thickness. Comparable applications of all-dielectric optical interference pigments are described, for example, in U.S. patent application No. CN100475915C by flex products corporation. The color shift of the all-dielectric optically variable pigment changes along with the change of the wave amplitude and the shift of the wavelength in the reflection peak of the pigment, however, the color development effect is not obvious, the saturation is not high enough, and the material presents a semitransparent effect.

F-P ultrathin absorption layer.

Another optical interference structure color film based on the fabry-perot metal-dielectric structure reduces the number of layers and the total cost required since the addition of the metal layer provides the opportunity to rapidly increase the reflectivity. However, the high absorptivity of the metal thin film material greatly reduces the transmittance and maximum reflectance, and an ultra-thin layer is often required to be deposited so as to improve the color rendering property of the material. Meanwhile, heavy metals are introduced into the traditional Fabry-Perot metal dielectric optical interference pigment by using chromium and nickel materials as semi-absorption layers, so that the full environmental protection of the material is restricted, and the Fabry-Perot metal dielectric optical interference pigment cannot meet the requirements on human safety and environmental friendliness. Comparable applications of optical interference films are described, for example, in US00613201 patent application of MERK, germany. In order to improve the color saturation, heavy metal layers such as chromium and nickel are introduced into the materials to serve as absorption layers, and the materials do not have the safety characteristic of a human body.

Disclosure of Invention

The invention provides an absorption interference type all-dielectric structural color film, which overcomes the defects in the background technology.

One of the technical schemes adopted by the invention for solving the technical problems is as follows: the absorption interference type all-dielectric structural color film comprises an interference film, wherein the interference film comprises an absorption type dielectric material layer and a visible light waveband transparent dielectric material layer, the refractive index of the absorption type dielectric material layer in a visible spectrum 380nm-760nm waveband is 1.8-4, the extinction coefficient is 0.01-2, and the refractive index of the visible light waveband transparent dielectric material layer is smaller than 1.7.

In one embodiment: the refractive index of the transparent medium material layer in the visible light band is 1.3-1.7.

In one embodiment: the difference between the refractive index of the absorption type medium material layer and the refractive index of the visible light wave band transparent medium material layer is more than or equal to 0.2.

In one embodiment: the transparent dielectric material comprises a plurality of absorption type dielectric material layers and a plurality of visible light wave band transparent dielectric material layers, wherein the absorption type dielectric material layers and the visible light wave band transparent dielectric material layers are alternately laminated.

In one embodiment: the absorption type dielectric material layer is made of one or a mixture of at least two of vanadium oxide, chromium oxide, cobalt oxide, aluminum nitride, titanium nitride, tin oxide, indium tin oxide, ferroferric oxide, iron oxide, titanium oxynitride, nickel oxide, copper oxide, or sub-oxides corresponding to titanium oxide, tantalum oxide and niobium oxide.

In one embodiment: the visible light wave band transparent medium material layer is made of one of silicon dioxide, aluminum oxide or metal fluoride or a mixture of at least two of the materials.

In one embodiment: the visible light wave band transparent medium material layer is made of organic monomer or polymer.

In one embodiment: also included is a substrate on which the interference film is laminated.

In one embodiment: the substrate is made of one of stainless steel, glass, polyethylene terephthalate, cellulose triacetate, polymethyl methacrylate, polycarbonate, polymethyl methacrylate composite material, polyimide, polypropylene, polyvinyl chloride, polyvinyl butyral, ethylene-vinyl acetate copolymer, polyurethane elastomer, polytetrafluoroethylene, fluoroethylpropylene or polyvinylidene fluoride.

The second technical scheme adopted by the invention for solving the technical problems is as follows: absorption interference type's all dielectric structure look film, its characterized in that: the interference film comprises a plurality of absorption type medium material layers and a plurality of visible light waveband transparent medium material layers which are alternately stacked, the low-refraction medium layer has the full-transparency performance of the visible light waveband, the high-refraction medium layer has the selective absorption function of the visible light waveband, and the number of the optical film layers is set between 3 and 30.

Compared with the background technology, the technical scheme has the following advantages:

the structural color film has higher saturation and obvious effect of color change along with angles, is safe to human bodies, and can be applied to the fields of cosmetics, makeup and the like which have high threshold on human body safety and the like. The film structure color is formed by alternately depositing an absorption type medium material and a visible light waveband transparent medium material, the reflective high saturation combines an interference effect and an absorption effect, has the characteristics of excellent color saturation, angle dependent heterochromous and environment friendliness, does not need a complex photoetching process, can generate a flamboyant color, and can determine the color characteristic through the material and the film structure parameter.

The structural color film increases structural color development freedom degree by utilizing an interference absorption combined design mode, utilizes high and low refractive indexes to form better reflection interference phase, realizes the reflection peak value of specified wavelength, and simultaneously, when the observation angle is changed, the visible light wave band absorption is more obvious, the high reflection characteristic of the central wavelength is ensured while the secondary peak absorption effect can be better realized, and more saturated color is presented. The absorption effect under the observation of a large angle also has the angular response characteristic, and the minimum point of the absorption spectrum and the reflection maximum wavelength are blue-shifted correspondingly, so that the reflection spectrum bandwidth can be compressed, and meanwhile, the central wavelength has smaller absorption effect and higher reflectivity, thereby increasing the color saturation and maintaining the reflection brightness of the material within the range of high color rendering performance. Compared with the structural color of the traditional titanium dioxide/silicon dioxide (TiO2/SiO2) transparent full-medium film, the full-medium structural color film is adopted, but the high saturation color characteristic similar to a Fabry-Perot metal medium structure is realized, the high color rendering performance is obtained, the limitation of chromium and nickel heavy metal materials is solved, and the full environmental protection property of the material is realized.

Drawings

The invention is further described with reference to the following figures and detailed description.

FIG. 1-1 is a graph showing reflection spectra of all-dielectric structure color films with the number of layers 7, 9, and 11.

Fig. 1-2 is a comparison graph of reflection spectra of an absorption interference type all-dielectric structure color film and a transparent all-dielectric structure color film.

Fig. 1-3 are graphs of spectral reflectance of all-dielectric structured color films of the absorptive interference type.

Fig. 1-4 are absorption rate diagrams of an all-dielectric structured color film of the absorption interference type.

FIG. 2-1 is a reflection spectrum diagram of a grass green color changing sky blue absorption interference type all-dielectric structure color thin film of an embodiment.

FIG. 2-2 is a graph of the reflection spectrum of a grass green to sky blue structure color film as a function of angle for one example.

FIGS. 2-3 are comparative images of the chromaticity of an all-dielectric non-absorbing structural color film R1 and an absorbing interference type structural color film R2 according to an example.

FIG. 3-1 is the reflection spectrum of the interference type all-dielectric structure color thin film with red changing to golden color in the second embodiment.

FIG. 3-2 is a graph of the reflectance spectrum of the red-to-golden structural color thin film of example two as a function of angle.

3-3 are comparative images of the chromaticity of the all-dielectric non-absorbing structural color film R1 and the absorbing interference type structural color film R2 of the second example.

FIG. 4-1 is a graph of absorbance versus wavelength for each layer of the three pink to emerald green structural color films of the examples.

FIG. 4-2 is a graph of reflectance spectra of three pink-to-emerald structural color films as a function of angle for the example.

FIGS. 4-3 are graphs showing the variation of the 0 degree (left) and 60 degree (right) chromaticity of the three pink-to-emerald green structure color film of the example.

FIG. 5-1 is a graph of the reflection spectrum of the four-red-to-orange-yellow absorption interference type all-dielectric structure color thin film of the embodiment.

FIG. 5-2 is a comparison of the chromaticity of the all-dielectric non-absorbing structural color film R1 and the absorbing interference type structural color film R2 of the example IV.

FIGS. 5-3 are graphs of the reflectance spectra of the four-red to orange-yellow structural color films of the examples as a function of angle.

FIG. 6-1 is a graph of the reflectance spectrum of the five orange-red to sky-blue structure color film as a function of angle for the example.

Detailed Description

The absorbing interference type all-dielectric optically variable structure color film comprises an interference film and a substrate, wherein the interference film is laminated on the substrate. The interference film comprises a plurality of absorption type medium material layers (high-refraction medium layers) and a plurality of visible light wave band transparent medium material layers (low-refraction medium layers), wherein the plurality of absorption type medium material layers and the plurality of visible light wave band transparent medium material layers are alternately laminated. The refractive index of the absorption type medium material layer is 1.8-4, the extinction coefficient is 0.01-2, the refractive index of the visible light wave band transparent medium material layer is 1.3-1.7, and the difference between the refractive index of the absorption type medium material layer and the refractive index of the visible light wave band transparent medium material layer is more than or equal to 0.2.

The absorption type dielectric material layer is selected from one of or a mixture of at least two of sub-oxides corresponding to vanadium oxide (V2O5), chromium oxide (Cr2O3), cobalt oxide (CoO2), aluminum nitride (ALN), titanium nitride (TiN), TiN oxide (SnO2), Indium TiN Oxide (ITO), ferroferric oxide (Fe3O4), iron oxide (a-Fe203 or Y-Fe203), titanium oxynitride (TiNO), nickel oxide (NiO), copper oxide (CuO) or titanium oxide (TiO2), tantalum oxide (Ta2O5) and niobium oxide (Nb2O 5).

In this embodiment, the medium-absorbing metal oxide material is used in the absorbing dielectric material layer, so that the structural color film has high color rendering property.

The visible light band transparent dielectric material layer is made of one or a mixture of at least two of silicon dioxide (Si02), aluminum oxide (Al2O3) or metal fluoride, such as magnesium fluoride (MgF2), aluminum fluoride (AlF3), cerium fluoride (CeF3), steel chloride (LaF3), sodium aluminum fluoride (Na 3AIF or NasAlFA), neodymium fluoride (NdF3), paper money fluoride (SmF3), barium fluoride (BaF2), calcium fluoride (CaF2) or lithium fluoride (LiF). According to the requirement, the layer of the transparent dielectric material in the visible light band can also be selected from organic monomers or polymers, such as one of diene, olefin, such as acrylate (such as methacrylate), perfluoroalkyl, polytetrafluoroethylene (Teflon) or Fluorinated Ethylene Propylene (FEP), or a mixture of at least two of the above materials.

The substrate is made of stainless steel, glass or optical plastic, and the optical plastic is made of one of polyethylene terephthalate (PET), cellulose Triacetate (TAC), polymethyl methacrylate (PMMA), polycarbonate/polymethyl methacrylate composite (PC/PMMA), Polyimide (PI), polypropylene (PP), polyvinyl chloride (PVC), polyvinyl butyral (PVB), ethylene vinyl acetate copolymer (EVA), polyurethane elastomer (TPU), Polytetrafluoroethylene (PTFE), Fluoroethylpropylene (FEP) or polyvinylidene fluoride (PVDF).

The multilayer absorption type medium material layer and the multilayer visible light wave band transparent medium material layer are alternately laminated, the number of the optical film layers is set between 5 layers and 30 layers, and the reflectance spectrum curve diagram of the all-dielectric structure color film with the number of the optical film layers being 7, 9 and 11 is shown in figure 1-1. The low-refraction medium layer has full transparency in visible light wave band, and the high-refraction medium layer has selective absorption function in visible light wave band to provide interference color and required color change characteristic, and is favorable for color effect of the structural color film.

The optical film laminated structure adopts a symmetrical regular structure or an asymmetrical non-regular structure, such as: the structure represents the thickness structure sequence of the absorption interference type all-dielectric film, capital letter H represents a high-refractive index absorption type dielectric material layer, capital letter L represents a visible light wave band transparent dielectric low-refractive index material layer, small letters a, b, c and d respectively represent thickness coefficients taking a quarter wavelength thickness as a unit, capital letter S represents the repeated periodicity of the same thickness sequence, and the combination optimization of the thickness and the sequence is carried out according to a given color target value on the basis of the initial film system structure.

Wherein: lambda [ alpha ]₀The/4 optical thickness is a well-known optical parameter defined as the product nd, where n represents the refractive index of the film and d represents the physical thickness of the film. Typically the optical thickness of a layer is expressed in terms of quarter-wave optical thickness (QWOT), i.e. equivalent to 4nd/λ, where λ represents a wavelength satisfying the quarter-wave optical thickness condition. The above a, b, c, d are 1QWOT proportionality coefficients with alternating lambda₀Dielectric multilayer films of optical thickness exhibit increased reflection due to constructive air/multilayer/substrate reflection interference.

Admittance Y of exit surface of each film layer of whole film stack_jCan be expressed as:

e.g. at a central wavelength lambda₀Where ((n)_Hn_L) The equivalent interface admittance of ^ S is:

the reflectivity at normal incidence is:

example (aHbL) ^ S aH a: b ^ 1:1

In the same way, reflection bands also appear in any film system with unequal thickness period and alternating high and low refractive indexes, and the high reflection condition meets the following conditions:

and corresponding combinations corresponding to the above proportionality coefficients of a:0.1-1, b:1-2 and a + b ═ 2 are included, and an absorption combination design is introduced through the extinction coefficient of the material itself. According to the required color change degree and the blue shift range of the spectrum, the thickness range of the single layer of the high refractive index dielectric layer is preferably between 5nm and 80nm, and the thickness range of the single layer of the low refractive index dielectric layer is preferably between 100nm and 600 nm. The physical thickness of the entire multilayer film is in the range of 200nm to 3000 nm, depending on the desired color characteristics.

In the case of a dielectric material having absorption characteristics in the visible light band, when the absorption film layer is simultaneously designed as an interference material, the absorption loss of the film system needs to be considered, and in this case, it is no longer possible to simply consider that R + T is 1. Assuming that the optical constant of the film is N-ik, k is not zero, which means that the film has absorption, the phase thickness of the film can be expressed as:

the transmittance and absorptance of the absorption-induced film system can be expressed as

A＝(1-R)(1-ψ)

It is assumed that the monolayer film of the system introduces a small absorption A_fPhysical quantity:

by the feature matrix calculation, the absorption introduced by the structured film system with optical thickness λ 0/4 for each layer with a: b ═ 1:1 is assumed to be:

(Final high refractive index)

In the same way, the outermost layer is made of low-refractive-index material, so that the extreme value reflectivity at the central wavelength is reduced because the absorption is increased:

in the formula n_HIs the refractive index of the high refractive index absorbing medium layer, n_LIs the refractive index of the low refractive index layer, k_HIs the extinction coefficient, k, of the high refractive index absorbing dielectric layer_LThe extinction coefficient of the low refractive index layer. The color gamut of the interference colors and the effect of the interference colors on the flop depend on the thickness of the layers of the multilayer system and the number of film layers. The maximum achievable reflectivity of a multilayer system depends not only on the number of layers and the refractive index of the layers, but also on the thickness of the absorption layer. Therefore, the thickness of the absorption medium layer is not easy to be overlarge, and the thickness is preferably 5nm to 80nm through design research. The thickness of the corresponding film layers is adjusted according to the refractive indexes of the all-dielectric material and the absorption-type dielectric material, and the spectrum of the multilayer film can be changed in the wavelength range of 400 nanometers (ultraviolet light) to 750 nanometers (red light) for selectively high reflection and high absorption performance of a low reflection area to increase saturation, as shown in fig. 1-3 and fig. 1-4.

In the present embodiment, the Physical Vapor Deposition (PVD) method is used to prepare the thin film, for example, ion beam sputtering deposition (IBS), magnetron sputtering deposition (MS), electron beam Evaporation (EB) and electron beam evaporation + ion assisted deposition (EB + IAD) are used to prepare the thin film; chemical Vapor Deposition (CVD) and liquid phase coating of pearlescent films are also possible.

The method for peeling the structural color film of the embodiment comprises the following steps: a layer system consisting of alternating layers of an all-dielectric transparent oxide material and an absorbing dielectric high refractive index material is deposited onto a release layer, which may be a coating soluble in aqueous solutions or organic solvents, such as polyvinyl alcohol, acrylic resins, polyvinyl acetate or chloride or fluoride. After the coating operation, the multiple coatings are separated by brushing, scraping or washing by dissolving the release layer in a water bath (possibly at a relatively high temperature) or in a solvent (possibly at a relatively high temperature). Or may be formed by a web coating process in which the layers are sequentially deposited on a web material by conventional deposition techniques to form a film structure which is then broken up and removed from the web, for example with a solvent to form a plurality of film pieces. The shredded flat sheet includes a plurality of thin film layers formed of various different materials. Generally, the pigment flakes have an aspect ratio of at least 2:1 and an average particle size of about 2um to about 20 um.

The absorption interference type all-dielectric angle-dependent heterochromatic structural color film can produce the following technical effects: 1. the interference absorption mode is utilized to increase the degree of freedom of structure coloring, and meanwhile, the absorption effect on secondary peaks is realized through an absorption type all-dielectric material, and peak values are reduced, so that the low-reflection region of a reflection spectrum is smooth, as shown in fig. 1-2; 2. the main reflection bandwidth effect is compressed, so that the color saturation of the structural color film is increased, the reflectance is adjusted by using the absorption type all-dielectric material, the color development capability of the material is increased within a proper brightness range, and the high saturation of the color is realized; 3. the interference design of all-dielectric materials is adopted, metal is not introduced to serve as an absorption layer, the actual interference color is kept while the high metal luster is obtained, and the angle-dependent color variation performance of the material is improved; 4. the layered one-dimensional photonic crystal structure is beneficial to large-scale preparation of the film material.