CN112708288A

CN112708288A - Magnetic structure color film

Info

Publication number: CN112708288A
Application number: CN202010435976.7A
Authority: CN
Inventors: 王雨思; 陈楠; 卜轶坤; 刘晋彤; 李青原; 冯坤; 陈昊
Original assignee: Xiamen University
Current assignee: Xiamen University
Priority date: 2020-05-21
Filing date: 2020-05-21
Publication date: 2021-04-27

Abstract

The invention discloses a magnetic structural color film, which comprises a multilayer interference magnetic structural color film, wherein the multilayer interference magnetic structural color film comprises a magnetic non-metal medium film material layer and a non-magnetic full-medium transparent material layer, the magnetic non-metal medium film material layer is made of a magnetic oxide material and has a high refractive index, and the magnetic non-metal medium film material layer is used as a magnetic functional film layer and a high refractive index medium layer which can participate in color regulation and brightness regulation. It has the following advantages: the structural color film can provide optical illusion images with motion characteristics according to the inclination of the images or the change of the positions of light sources irradiating the images, and simultaneously ensure that pigment flakes formed by the films have obvious optical color changing characteristics, magnetic response functions and human-friendly characteristics.

Description

Magnetic structure color film

Technical Field

The invention relates to the technical field of structural color films, in particular to a magnetic structural color film with human body safety.

Background

The magnetically structured color film having an alignment or orientation can be used in optically variable films, inks, paints, security devices or printing processes to create images with dynamic optical effects, to increase the authenticity of the printed product image and to provide recognizable three-dimensional object patterns. The structural color film material with magnetic response has both decorative and practical properties. Examples of applications are printing on credit card and authorization software documents, printing on banknotes in colour transfer images, and for enhancing colour appearance of articles such as automotive paints and wheel covers, and for forming more attractive optically variable security features on financial and high value documents and other products, and providing optical security images which are difficult for counterfeiters to reproduce. The optically variable effect is caused by superposition of light waves reflected for multiple times based on optical interference effect, so that the material obtains color shift effect. The reflection maxima vary in position and intensity as the viewing angle varies due to varying interference effects caused by differences in optical path length differences in different material layers, and are selectively enhanced in specific wavelengths. The magnetic structure color film in the prior art has the following problems:

1. the magnetic layer introduces a reflectivity reduction problem.

Smitt Schmid et al have attempted to incorporate magnetic layers in a multi-layer sheet, such as the layered color shifting structure disclosed in european patent EP686675B1 (hereinafter "Schmid") which includes a magnetic layer between an underlying dielectric layer and a central aluminum layer: oxide layer/absorber layer/dielectric layer/magnetic layer/aluminum layer/magnetic layer/dielectric layer/absorber layer/oxide layer. Schmid utilized aluminum flakes and coated these flakes with a magnetic material, since aluminum is the second bright metal (behind silver), the overlying magnetic material reduces the reflective properties of the pigment and the reflectivity of the magnetic material is reduced.

2. Corrosion of the basic structure.

P. rocha et al 2004.08.26 discloses a thin film magnetic color shifting structure (W02004/072186EN) with magnetic material as a magnetic core surrounded by a reflective layer to improve the reflective properties of the magnetic material, the thin film material having the following structure: colored superstrate/absorber layer/dielectric layer/reflector layer/magnetic layer/reflector layer/substrate. The above structure has a significant disadvantage: if the algebraic difference in atomic potential of two metals on the precious metal table is greater than +/-0.3 volts, galvanic corrosion will occur between the two metals. The potential of the aluminum/nickel pair is-1.41 v, indicating that the most common 7-layer design, such as the Cr/MgF2/Al/Ni/Al/MgF2/Cr structure, is particularly sensitive to exposure to alkaline or its base solutions when immersed in an electrolyte or exposed to a humid environment.

3. The human body safety problem.

Another of the most commonly used fabry-perot magnetic structural color materials utilizes heavy metals as the skin material, and chromium-containing materials are widely used in paint compositions because of their favorable light absorption and corrosion resistance properties. In many coating compositions, such as interference coating compositions, chromium-containing material layers are used as absorber layers in multilayer pigment flakes. Chromium metal layers can be used as absorbing layers to improve material color development as disclosed in U.S. Pat. No. 3,858,97 to Baird et al, 1/7 in 1975, U.S. Pat. No. 5,059,245 to Phillips et al, 10/22 in 1991, U.S. Pat. No. 5,571,624 to Phillips et al, 1/5 in 1996, U.S. Pat. No. 6,132,504 to Kuntz et al, 10/17 in 2000, and U.S. Pat. No. 6,156,115 to Pfaff et al, 12/5 in 2000, and in Flex products company W02002/024818. However, many of the chromium-containing materials in the absorptive layers using prior art coating compositions are harmful to human health. For example, metallic chromium and trivalent chromium oxides can cause skin, eye, respiratory and gastrointestinal pain. Furthermore, these materials can be oxidized to form hexavalent chromium species, which are generally toxic and carcinogenic. Furthermore, the use of chromium-containing alloys in the absorption layer of prior art coating compositions often also contains nickel, which is toxic and carcinogenic. Thus, many prior art coating compositions based on chromium-containing materials pose potential health and environmental hazards.

Disclosure of Invention

The invention provides a magnetic structural color film, which overcomes the defects in the background art.

The technical scheme adopted by the invention for solving the technical problem is as follows: a magnetic structure color film comprises a multilayer interference magnetic structure color film, wherein the multilayer interference magnetic structure color film comprises a magnetic nonmetal medium film material layer and a nonmagnetic full-medium transparent material layer, the magnetic nonmetal medium film material layer is made of a magnetic oxide material and has a high refractive index, and the magnetic nonmetal medium film material layer is used as a magnetic functional film layer and a high refractive index medium layer capable of participating in color regulation and brightness regulation.

In one embodiment: the multilayer interference magnetic structure color film comprises a plurality of magnetic non-metal medium film material layers and a plurality of non-magnetic full medium transparent material layers which are alternately formed.

In one embodiment: the refractive index of the magnetic oxide material in a visible spectrum wave band of 380nm-760nm is 1.8-4.0, and the extinction coefficient is 0.001-3.

In one embodiment: the magnetic oxide material is at least one of iron, manganese, cobalt magnetic metal oxide or spinel ferrite based on the magnetic metal oxide or spinel ferrite material or the mixture of at least two of the materials which are friendly to human body.

In one embodiment: the magnetic oxide material is at least one of ferric oxide, ferrous oxide, nickel oxide, cobalt oxide, nickel iron oxide, ferroferric oxide, manganese oxide, ferromanganese oxide and cobalt iron oxide or a mixture of at least two of the materials.

In one embodiment: the refractive index of the non-magnetic all-dielectric transparent material layer is 1.3-2.6.

In one embodiment:

the non-magnetic full-medium transparent material layer is one of silicon dioxide, aluminum oxide, magnesium fluoride, aluminum fluoride, cerium fluoride, steel chloride, sodium aluminum fluoride, neodymium fluoride, paper money fluoride, barium fluoride, calcium fluoride, lithium fluoride, yttrium oxide, bismuth oxide, neodymium oxide, titanium dioxide, trititanium pentoxide, tantalum pentoxide, niobium pentoxide, hafnium oxide, zirconium oxide, zinc sulfide, lanthanum titanate and a mixture of at least two of the above materials.

In one embodiment: the non-magnetic all-dielectric transparent material layer comprises a middle-high refractive index non-magnetic dielectric layer and a low refractive index non-magnetic dielectric layer, wherein the middle-high refractive index non-magnetic dielectric layer and the low refractive index non-magnetic dielectric layer are alternately arranged.

In one embodiment: the multilayer magnetic thin film material layer is dispersedly clamped between a plurality of layers of middle and high refractive index non-magnetic medium layers and low refractive index non-magnetic medium layers.

In one embodiment: the difference between the refractive index of the magnetic non-metal dielectric thin film material layer and the refractive index of the non-magnetic full-dielectric transparent material layer in the visible light wave band is more than or equal to 0.2.

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

the multilayer interference magnetic structure color film comprises a magnetic non-metal medium film material layer and a non-magnetic full-medium transparent material layer, wherein the magnetic film material layer is made of a magnetic oxide material and has a high refractive index, the magnetic film material layer is used as a magnetic functional film layer and a high refractive index medium layer capable of participating in color regulation and brightness regulation, and the magnetic film material layer can absorb short waves to weaken a secondary peak so as to increase the saturation of colors. The structural color film can provide optical illusion images with motion characteristics according to the inclination of the images or the change of the positions of light sources irradiating the images, and meanwhile, the pigment flakes are ensured to have obvious optical color changing characteristics, magnetic response functions and human-friendly characteristics.

The magnetic non-metal medium film material layer not only serves as a magnetic functional film layer, but also serves as a high-refractive-index medium layer to participate in color regulation and reflectivity regulation (different from the traditional ' magnetic metal medium film structure color material ' in which a magnetic material serves as an insertion layer, has the function of only serving as a magnetic function and does not have the color regulation function '), and has obvious optical color-changing characteristics, a magnetic response function and human-friendly characteristics. A significant colour change is perceived when the angle of incidence of the light is changed or when the viewing angle of the observer is changed, this colour change being the result of the combined effect of selective absorption by the materials of which the layers are composed and wavelength dependent interference effects. Furthermore, the magnetic response characteristics may be used to create security features that cannot be observed with the naked eye, to create three-dimensional images for security devices, or to add decorative features to a product. These security features, which are invisible to the naked eye, are provided by the combined design of the metal oxide magnetic layers between the full dielectric layers.

Drawings

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

FIG. 1-1 is a graph of complex planar iso-reflectivity curves.

FIG. 1-2 is a graph of the reflectivity, absorption and optical admittance of a five-layer film structure.

FIGS. 1-3 are two graphs of the reflectivity, absorptivity, and optical admittance of a five-layer film structure.

Fig. 1-4 illustrate the formation of optical images with motion features oriented in arches under an applied magnetic field.

Fig. 1-5 are magnetic light-variable patterns produced by a combined magnetic field.

FIG. 2-1 is a schematic structural diagram of a multilayer interference magnetic structure color film according to an embodiment.

Fig. 2-2 is a graph of absorbance versus wavelength for a structural color film of an example.

FIGS. 2-3 are graphs of reflectance versus wavelength for films of structural colors according to examples.

FIGS. 2-4 are graphs showing the locus of the chromaticity coordinate change of the structural color film according to the embodiment.

FIG. 3-1 is a graph of absorbance versus wavelength for films of the second structural color of the example.

FIG. 3-2 is a graph of reflectance versus wavelength for films of the second structural color of the example.

Fig. 3-3 are plots of the locus of the chromaticity coordinate change of the film of the second structural color in the example.

FIG. 4-1 is a graph of total absorption versus wavelength for the three structural color films of the example.

Fig. 4-2 is a graph of the layer-by-layer absorbance versus wavelength of the three structural color films of the example.

FIGS. 4-3 are graphs of the reflectance versus wavelength of the three structural color films of the examples.

FIG. 5-1 is a graph of the total absorption rate versus wavelength of the four structure color films of the example.

FIG. 5-2 is a graph of the absorption rate of the four structural color films of the example as a function of wavelength.

5-3 are graphs of the reflectance versus wavelength of the four structural color films of the examples.

Detailed Description

The utility model provides a magnetic structure look film, interfere magnetic structure look film including the multilayer that is one-dimensional photonic crystal structure, this multilayer interferes magnetic structure look film includes magnetic nonmetal dielectric film material layer and the transparent material layer of non-magnetic full medium, this magnetic film material layer is made by magnetic oxide material and has the high refractive index, this magnetic film material layer not only is as magnetic function rete but also participates in colour regulation and control and reflectivity regulation as the high refractive index dielectric layer, this magnetic film material layer can absorb the shortwave in order to weaken the secondary peak to increase the saturation of color.

The multilayer interference magnetic structure color film comprises a plurality of magnetic film material layers and a plurality of non-magnetic all-dielectric transparent material layers which are alternately formed. The refractive index of the magnetic oxide material in a visible spectrum wave band of 380nm-760nm is 1.8-4.0, and the extinction coefficient is 0.001-3. The magnetic oxide material is selected from magnetic iron oxide materials.

The thickness of the magnetic thin film material layer is 10-90 nanometers. The magnetic oxide material is at least one of ferric oxide, ferrous oxide, nickel oxide, cobalt oxide, nickel iron oxide, ferroferric oxide, manganese iron oxide, cobalt iron oxide and the like which are friendly to human bodies and are based on iron, manganese, cobalt magnetic metal oxide or spinel ferrite materials or a mixture of at least two of the materials.

The refractive index of the non-magnetic all-dielectric transparent material layer is 1.3-2.6. The non-magnetic full-medium transparent material layer is one of silicon dioxide, aluminum oxide, magnesium fluoride, aluminum fluoride, cerium fluoride, steel chloride, sodium aluminum fluoride, neodymium fluoride, paper money fluoride, barium fluoride, calcium fluoride, lithium fluoride, yttrium oxide, bismuth oxide, neodymium oxide, titanium dioxide, trititanium pentoxide, tantalum pentoxide, niobium pentoxide, hafnium oxide, zirconium oxide, zinc sulfide, lanthanum titanate and a mixture of at least two of the above materials.

The difference between the refractive index of the magnetic non-metal dielectric thin film material layer and the refractive index of the non-magnetic full-dielectric transparent material layer in the visible light wave band is more than or equal to 0.2.

The non-magnetic all-dielectric transparent material layer also comprises a middle-high refractive index non-magnetic dielectric layer and a low refractive index non-magnetic dielectric layer. The medium and high refractive index non-magnetic medium layers and the low refractive index non-magnetic medium layers are alternately arranged. The multilayer magnetic thin film material layer is dispersedly clamped between the middle-high refractive index non-magnetic medium layer and the low refractive index non-magnetic medium layer according to the alternate deposition mode of the high-low refractive index materials and different structural color requirements, and is specifically set out in the following examples.

The magnetic thin film material layer is used as a magnetic functional film layer to generate magnetic control characteristics. The magnetic control characteristic is similar to a three-dimensional effect, the material is exposed to an external magnetic field, the plane of the unoriented material is parallel to the surface of the coating layer, and under the action of the external magnetic field, the particle orientation is rearranged, so that the longest part of the thin film sheet is aligned with the magnetic field line. In this case, the surface of the sheet deviates from the viewer, and the degree of deviation depends on the strength of the magnetic force. Under the condition of limit or maximum orientation, the coating film is black. When the color deviates from black, the color of the plane surface of the film is gradually changed, and a colored three-dimensional-like effect is obtained, which is similar to a dynamic effect moving along with the change of the observation angle. A method for creating a three-dimensional-like image by using a magnetic thin film can be referred to in detail in U.S. patent application No. 13676.167 entitled "method for producing a patterned coated object by using magnetic pigments".

The magnetic structure color film of the present embodiment is different from the existing magnetic structure color film in that: the structural color film of the invention not only breaks through the basic structure of the traditional Fabry-Perot cavity, but also obtains the magnetic controllable structural color film material with high color saturation through the alternative design of the magnetic metal oxide and the all-dielectric oxide material. First, the corrosion problem of the aluminum nickel layer in the structure is fundamentally removed, and the sheet can be substantially prevented from being corroded when exposed to a harsh environment. Secondly, the problem that many chromium-containing materials in the absorbing layer in the prior art are harmful to human health is solved. Thirdly, the magnetic metal oxide material is adopted to be simultaneously used as three functional layers of the dielectric layer, the reflecting layer and the magnetic layer for combined design, so that the structural design and the preparation process of the traditional film with complicated structural color are greatly simplified.

In a magnetically structured color film of this embodiment, the magnetic layer having a color shifting function is designed in combination to provide a film having a lower coercivity than standard recording materials, as compared to conventional "magnetic" materials such as: nickel, cobalt, iron and their alloys are significantly different. Materials with too strong a remanence when patterned or oriented with paint or ink mix, the material is blackened in hue and insufficiently saturated in color due to the magnetic material easily clumping together, providing coverage for high color development with conventional flakes, the need to have a high concentration of flakes associated with flake overlap, making the cost of the coating higher. Advantageously, the magnetically controllable structural color film of the present invention using the multi-layer metal oxide composite design is more easily dispersed without clumping than magnetic films of the prior art to provide a low density, low cost, and high saturation magnetic structural color film coating.

In the magnetic structure color film of the present embodiment, it is important to maintain a high reflection layer in order to maintain high luminance and chromaticity. The process of designing the structural color of the thin film by using the magnetic metal oxide material as the three functional layers of the dielectric layer, the reflective layer and the magnetic layer at the same time for combined design will be discussed in more detail below.

The magnetic layer adopts at least one of iron, manganese, cobalt magnetic metal oxide or spinel ferrite materials or a mixture of at least two of the materials, which are friendly to human bodies, such as ferric oxide, ferrous oxide, nickel oxide, cobalt oxide, nickel iron oxide, ferroferric oxide, manganese oxide, ferric cobalt oxide and the like. The magnetic materials are selected based on their reflective or absorptive properties and their magnetic properties, which simultaneously serve as high index dielectric materials in the design of interference structures. By comparing the reflectivity and the transmissivity curves of the single-layer ferric oxide sample films with the thicknesses of 20-50 nanometers and 60-90 nanometers respectively, the sum of the transmissivity and the reflectivity of the sample film with the thickness of 20-50 nanometers is 80-90%, the sum of the transmissivity and the reflectivity of the sample film with the thickness of 60-90 nanometers is 65-80%, and the value of the sum of the transmissivity and the reflectivity of the sample film with the thickness of 60-90 nanometers is analyzed to be larger than that of the sample film with the thickness of 20-50 nanometers according to the formula T + R + A being 1, so that the thicker the ferric oxide film is, the lower the transmissivity is, the higher the reflectivity is, the higher the absorption is, and the optical characteristics of the metal material are closer. The typical thickness of the magnetic material is 10-90 nm, and further, in order to enable the metal oxide to have better magnetic control characteristics, the thickness of the magnetic material is 20-70 nm, so that the magnetic material has better response characteristics. Taking a single-layer iron oxide magnetic film as an example, the optical constants of the single-layer iron oxide film prepared by the experiment are measured by a full spectrum fitting method, and the obtained result is basically consistent with the theoretical analysis. The experimental result shows that the optical constant of the absorption type dielectric material obtained by fitting is more accurate, and the film preparation process is good.

The dielectric layer in the invention functions as a spacer and interference combination design in the structure color thin film structure. The layers are made to have an effective optical thickness to provide interference colors and desired color shifting characteristics. To assist the color effect of the structured color flakes, the dielectric layer may be transparent, or have selective absorption. Optical thickness is a well-known optical parameter defined as the product nd, where n represents the refractive index of the layer and d represents the physical thickness of the layer. 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 color-changing medium layer required by the invention is made of a conventional transparent non-magnetic full-medium thin film material, the refractive index of the color-changing medium layer is distributed from 1.3 to 2.6, and the non-magnetic medium material with low refractive index suitable for the non-magnetic material of the medium layer is one of silicon dioxide (SiO2), aluminum oxide (Al2O3), magnesium fluoride, aluminum fluoride, cerium fluoride, steel chloride, sodium aluminum fluoride, neodymium fluoride, banknote fluoride, barium fluoride, calcium fluoride, lithium fluoride and a mixture of at least two of the above materials. Other low refractive index materials having a refractive index of about 1.65 or less; suitable medium refractive index non-magnetic dielectric materials for the non-magnetic material of the dielectric layer include one of yttrium oxide (Y2O3), bismuth oxide (Bi2O3), or neodymium oxide (Nd2O3), and mixtures of at least two of the foregoing; high refractive index non-magnetic dielectric materials suitable for the non-magnetic material of the dielectric layer include one of titanium dioxide (TiO2), trititanium pentoxide (Ti3O5), tantalum pentoxide (Ta2O5), niobium pentoxide (Nb2O5), hafnium oxide (HfO2), zirconium oxide (ZrO2), zinc sulfide (ZnS) or lanthanum titanate LaTiO3(H4), and mixtures of at least two of the foregoing.

In all dielectric material interference designs, quarter-wave (QW) stacks are one of the most common multilayer film systems, and their general form can be defined as s | (HL)^PH | Air. Wherein H and L represent an optical thickness of 1/4 lambda₀The high refractive index and the low refractive index of the film layer are respectively n_HAnd n_L；(LH)^PThe sequence representing LH is repeated P times, P being an integer; s is a substrate and has a refractive index of n_S(ii) a Air is Air; this stack of films has a common 2P +1 layer and thus the reflectivity can be expressed as:

when the weak absorption film layers of iron oxides are simultaneously used as interference materials for combined design, the absorption loss of a film system needs to be considered, the optical constant of the film layers is N-ik, k is not zero and represents that the film layers have absorption, the phase thickness of each film layer can be represented as that the corner mark j represents the surface layer serial number, and d represents the layer thickness:

substituting the above into a feature matrix

Calculating, it represents the film property, the absorption-injection layer k is not zero and represents the film layer has absorption, eta₀η_jη_sRespectively represent the general optical admittance of an incident medium, a film and a substrate.

The multilayer film is only the superposition of single-layer films, and the characteristic matrix of the multilayer film is obtained by repeatedly using the formula:

an equivalent optical admittance of

Reflection absorption

A transmission coefficient of

Therefore, it reflects

Transmission through

Taking the absorption interference design of an absorption type all-dielectric material, a quarter-wave (QW) film stack is taken as an example: s | (aLBA)^PaL | Air. Wherein, the thickness of A is b/4 lambda₀L represents an optical thickness of a/4 lambda₀L is a low refractive index film layer, and the refractive indexes are respectively n_AAnd n_L；(LA)^PThe sequence representing LA is repeated P times, P being an integer; s is a substrate and has a refractive index of n_S(ii) a Air is Air; the membrane stack has a total of 2P +1 layers.

The maximum achievable reflectivity of multilayer systems, explained by admittance diagram, therefore depends not only on the number of layers and the refractive index of the layers, but also on the thickness of the magnetic layers. Assuming that the light wave is guided by the incident medium Y₀. Entering the medium Y_SWhen Y is α + i β, the reflectance R of the light wave is:

unfolding the above formula:

drawing a circle curve comparison, and obtaining a circle curve of the equivalent R by knowing a given value R: circle center:

radius:

as shown in fig. 1-1, given different R values, a set of equal reflectivity curves can be plotted on the admittance complex coordinate, where the centers of the equal reflectivity curves all fall on the real number axis, and when R is 0, the circle is reduced to a point (y is 0)₀0), these circles correspond to reference curves, and if the isoadmittance of a film series falls within a circle, the reflectance of the film series is the R value of the circle, and fig. 1-1 are iso-reflectance maps, labeled as iso-reflectance values.

Now, when the physical thickness d of a is 36nm and the physical thickness d of L is 334nm, the sequence of LA is repeated 2 times, the black line is the full medium L, the red line is the absorbing medium a, and the five-layer admittance at the central reflection wavelength 531nm is shown in fig. 1-2. The sequence of LA was repeated 2 times with a physical thickness d of 56nm and L of 334nm, the black line being the full medium L, the red line being the absorbing medium a, and the five-layer admittance at a central reflection wavelength 565nm being shown in fig. 1-3. The comparative analysis of the admittance chart shows that: 1) the absorption layer plays a role in weakening secondary peaks, and the absorption effect at short waves and long waves is obvious, so that the thickness of the absorption layer is not easy to be too thin; 2) according to the iso-reflectivity curve admittance graph, the radius of the full-medium admittance circle R1 at the large-value reflection wavelength (531nm) in the graph of FIGS. 1-2 is approximately the same as that of the absorption medium admittance circle R2, and the radius of the full-medium admittance circle R1 at the maximum reflection wavelength (565nm) in the graph of FIGS. 1-3 is greater than that of the absorption medium admittance circle R2, so that the maximum reflection is attenuated due to the excessively thick absorption layer.

The maximum achievable reflectivity of a multilayer system depends not only on the number of layers and the refractive indices of the layers, but also on the thickness of the magnetic layers. Further, the thickness of the absorption layer is not too large, and is preferably 20 to 70 nm. The magnetic metal oxide is used as an absorption film layer designed according to structural color and a high-refractive-index film layer superposed by interference besides being used as a magnetic functional film layer, and is expressed as M in a film stack structure; and the high/low dielectric optical film stack is formed by alternately designing transparent low-refractive-index non-magnetic dielectric layers (L) or medium/high-refractive-index non-magnetic dielectric layers (H). The magnetic oxide material can also be inserted into the fully transparent high-low refractive index dielectric film stack to participate in interference design. When one medium layer is made of a high/low medium stack, the color change angle depends on the combination of optical constants and thicknesses of materials of each layer in the medium stack and the number of layers of films, and meanwhile, the magnetic layer has a magnetic orientation function as a magnetic control response medium.

The initial design membrane system structure: (bLaM) ^ S, (bLaM) ^ SbL, (bLaMbL) ^ S, (aMbL) aM, (aMbLaM) ^ S, (bLcHaM) ^ S, (bLaMcH) ^ S, (cHbLaM) ^ S, (cHaMbL) ^ S. The structure represents a thickness structure sequence of the magnetic controllable all-dielectric film, wherein capital letter L represents a non-magnetic all-dielectric transparent medium-low refractive index material layer, capital letter H represents a non-magnetic all-dielectric transparent high refractive index material layer, capital letter M represents a magnetic non-metallic dielectric film material layer, lowercase letters a, b and c respectively represent thickness coefficients taking quarter-wavelength thickness as a unit, and capital letter S represents the repeated period number of the same thickness sequence. The use of magnetic oxides for single-layer or multi-layer composite designs is also applicable.

The substrates used for the interference layer system were thin films deposited from K9 glass with a diameter of 80 mm, a thickness of 2 mm and a surface quality of 20/10. Of course, as the substrate, one of optical plastic substrates such as stainless steel 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) may be used, as needed.

The structured color film of the present invention can be prepared using conventional well-known film deposition techniques. Such thin film deposition techniques include, and are not limited to: physical Vapor Deposition (PVD), Chemical Vapor Deposition (CVD), Plasma Enhanced (PE) variants such as Plasma Enhanced Chemical Vapor Deposition (PECVD) or plasma enhanced chemical vapor deposition, sputtering, electrolytic deposition, bead-blasting-like liquid phase deposition and other similar deposition methods that can form separate and uniform thin film layers. The method of combining electron beam evaporation and ion assisted deposition is taken as an example for illustration. The RF ion source is used for ion-assisted bombardment in the material growth process, and the volume weight and the adhesive force of the film are improved. The coating material is bombarded by energetic ions in the plasma, for example argon ions, thereby atomizing. Atoms and molecules of the atomized coating material deposit on the substrate and form a thin layer. The structure of the layer can be influenced by appropriate measures, such as bombarding the grown layer with ions in a plasma.

The embodiment prepares the alloy from manganese iron oxide (MnFe)₂O₄) And the all-dielectric materials of silicon dioxide (SiO2) and niobium pentoxide (Nb)₂O₅) The magnetic all-dielectric oxide structural color film is formed. The thin film was deposited using K9 glass with a diameter of 80 mm, a thickness of 2 mm and a surface quality of 20/10 as the substrate. The deposition process parameters for the coating system are shown in the table below. And controlling the film thickness deposition by adopting a quartz crystal oscillator.

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 a magnetic metal oxide high refractive index material is deposited onto the release layer. The layer system formed on the substrate is removed by dissolving the release layer, and the resulting interference pigment in flat sheet form is washed and dried, and the pigment is heat-treated in a nitrogen stream at 100-300 ℃. 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 organic carrier adding method of the embodiment comprises the following steps: the material carrier includes a polymeric composition or an organic binder such as at least one of an alkyd resin, a polyester resin, an acrylic resin, a polyurethane resin, a vinyl resin, an epoxy resin, styrene, and similar materials. Examples of suitable resins include melamine, acrylates such as methyl methacrylate, ABS (acrylonitrile butadiene styrene) resins, alkyd based ink and coating formulations, and various mixtures thereof. Preferably, the pigment medium also includes a solvent for these resins, such as an organic solvent or water. The flakes combined with these pigment media produce a colorant composition that can be used directly as a coating, ink, or moldable plastic material. The colorant compositions can also be used as additives for conventional coatings, inks or plastic materials.

The application scenario of the present embodiment is as follows: in each of the above embodiments, the magnetically controlled structured color film has a significantly varying appearance of chromaticity and hue as a function of the angle of incident light or the angle of observation of the observer. This optically variable effect allows the film to be broken up and dispersed as flakes in a liquid medium such as paint or ink to produce various color-changing coloring compositions for application to objects or paper. Magnetic pigment flakes can be oriented in a number of ways. After applying the pigment to a medium, a magnetic field can be used to orient the flakes. Examples of suitable media include paper, plastic, metal, wood, leather, or fabric. Printing techniques include gravure, stamping, intaglio, flexographic, silk screen, spray or offset printing, which may be combined to create a pattern. The magnetic orientation process is illustrated in fig. 1-4. Finally, the pigment coating is cured to fix the reoriented particles or flakes in a non-parallel position to the surface of the pigment coating, thereby creating an image, such as a three-dimensional image, on the surface of the coating. The pigment coating may comprise various interfering or non-interfering magnetic particles or flakes, such as magnetic color-changing pigments. The aligned pigment flakes of the magnetically controllable structured color film flakes used to produce moving objects are oriented in an arcuate configuration under an applied magnetic field to form an optical image having a motion characteristic as shown in FIGS. 1-4. The magnetically structured color film flakes can be simultaneously aligned in a magnetic field to produce one or more motion features, such as a rolling bar that appears to move when the image is tilted. These images can form security features on documents of value, such as banknotes.

Example one

A yellow-green sky-blue high-saturation magnetic controllable film structure color material comprises a substrate and a multilayer interference magnetic structure color film arranged on the substrate, wherein the multilayer interference magnetic structure color film comprises Al₂O₃All dielectric transparent oxide material layer and Fe₂O₃The metal oxide high refractive index material layer, fig. 2-1 is a schematic structural diagram thereof, and the film layers in the diagram are only a schematic layer number diagram and do not represent the actual thickness of the film layers. Wherein the magnetic layer is designed as an absorbing interference layer combination and has a magnetic response characteristic.

The substrate is a K9 glass deposited film with the diameter of 80 mm, the thickness of 2 mm and the surface quality of 20/10, and can also be one of optical plastic substrates such as polyethylene terephthalate (PET), Triacetylcellulose (TAC), polymethyl methacrylate (PMMA), polycarbonate/polymethyl methacrylate composite material (PC/PMMA), Polyimide (PT), polypropylene (PP), polyvinyl chloride (PVC), polyvinyl butyral (PVB), ethylene vinyl acetate copolymer (EVA) or polyurethane elastomer (TPU), Polytetrafluoroethylene (PTFE), Fluoroethylpropylene (FEP) or polyvinylidene fluoride (PVDF) and the like according to requirements.

Based on the quarter-wave film stack structure, ten film stacks with the structure of Air/(LM) 5L/Glass are designed, and the K9 Glass is provided with a low-refractive-index material L of Al₂O₃Layer of the low refractive index material Al₂O₃The layer is provided with a high-refractive-index magnetic material M of Fe₂O₃The layers of the high-refractive index material film layers and the low-refractive index material film layers are alternately arranged, and eleven layers are arranged in total, and the structure is schematically shown in a figure 2-1. The number of layers of the low refractive index film layer and the high refractive index film layer can be increased or decreased according to needs. Where the thicknesses of the high and low index materials are all quarter-wavelength optical thicknesses at a center wavelength of 1000nm, the physical thicknesses for each material in the structure are the same, which is a regular thickness sequence.

In this embodiment, the layer number in the film structure is the same as the layer number in the layer thickness table, and the high refractive index material is magnetic metal oxide Fe₂O₃Layer of low refractive index Al₂O₃The layer, film material layer structure and thickness parameters are as follows in table 2-1.

As can be seen from FIG. 2-2, the absorption of the magnetic oxide dielectric material in the visible light band is obvious, and Al₂O₃The absorption of the transparent all-dielectric material is almost negligible. Meanwhile, the combined design of the absorption interference film layer enables the material to have obvious attenuation effect of secondary peaks along with the increase of the angle of an incident light source, further enables a reflection curve to become smooth, and increases the identification capability of human eyes on color drift. As can be seen from FIGS. 2-3, the color reflectivity-wavelength curve of a high-saturation magnetically controllable thin-film structure safe to human body has a peak wavelength of 570nm in a green band, and the peak reflection peak is towards short wave with the increase of angleMoving, the reflection peak wavelength shifts to 470nm at 60 degree observation angle, the material provides significant color change, and the chromaticity shift trace is as shown in fig. 2-4.

In a vacuum vapor deposition apparatus, a layer system consisting of alternating layers of a low refractive index material and a high refractive index material is deposited onto a release layer, the central layer employing a layer of an absorbing material. The layer system formed on the substrate is removed by dissolving the release layer, and the resulting interference pigment in flat sheet form is washed and dried, and the pigment is heat-treated in a nitrogen stream at 100-300 ℃. 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).

The magnetic layer according to one embodiment provides a magnetic response characteristic, provides an optical illusion image with motion characteristics according to the inclination of the image or the change of the position of a light source irradiating on the image, and ensures that the pigment flakes have obvious optical discoloration characteristics and a magnetic response function and human-friendly characteristics.

Example two

The orange-red-to-yellow-green all-dielectric high-saturation magnetic interference film structural color material comprises a substrate and a multilayer interference structural color film, wherein the multilayer interference structural color film comprises an all-dielectric transparent oxide material layer with low refractive index and high refractive index and a magnetic oxide material layer.

The substrate was a K9 glass deposited film having a diameter of 80 mm, a thickness of 2 mm and a surface quality of 20/10. The K9 glass is provided with a high-refractive-index material Nb₂O₅Layer of the high refractive index material Nb₂O₅On the layer is provided with a low refractive index material SiO₂Layer of a material of low refractive index SiO₂A magnetic oxide material MnFe on the layer₂O₄The high and low magnetic refractive index material film layers are alternately arranged, and the plurality of layers are totally thirteen layers.

In this embodiment, the high refractive index material is Nb₂O₅The second layer is made of low-refractive-index material SiO₂The third magnetic layer is made of MnFe oxide material₂O₄The film material layer structure and thickness parameters are shown in the following table 2-2.

The absorption of the all-dielectric material in the visible light band is not obvious enough, and it can be seen from fig. 3-1 that the attenuation effect of the secondary peak is always obvious along with the increase of the angle of the incident light source, and the absorption at the short wave becomes larger along with the increase of the angle. As can be seen from the graph in FIG. 3-2, the first-order interference peak bandwidth of the reflectivity-wavelength curve of the high-saturation all-dielectric thin-film structure color material with human safety in the long-wave band is narrowed, the identification capability of human eyes on color drift is improved, and the color saturation of the material is increased. The chromaticity shift trajectory is shown in fig. 3-3. The wavelength of the main reflection peak is 650nm in vertical observation, the integral color development is orange red because the reflection area covers the red to yellow area, the wavelength of the main reflection peak is shortened to 560nm under the condition of inclining the observation angle of 60 degrees, the reflection bandwidth is narrowed, the saturation is improved, and the integral color development is yellow green.

In a vacuum vapor deposition apparatus, a layer system consisting of alternating layers of a low refractive index material and a high refractive index material is deposited onto a release layer, the central layer employing a layer of an absorbing material. The layer system formed on the substrate is removed by dissolving the release layer, and the resulting interference pigment in flat sheet form is washed and dried, and the pigment is heat-treated in a nitrogen stream at 100-300 ℃. After the coating operation, the multiple coatings are separated by dissolving the release layer in a water bath, or by brushing, scraping or, preferably, washing in a solvent.

EXAMPLE III

A magnetic controllable film structural color material for changing sky blue into purple red comprises a substrate and a multilayer interference magnetic structural color film, wherein the substrate adopts a K9 glass deposition film with the diameter of 80 mm, the thickness of 2 mm and the surface quality of 20/10. The multilayer trunkThe magnetic structure color film comprises SiO₂All dielectric transparent oxide material layer of (a), Nb₂O₅Metal oxide high refractive index material layer and Fe₂O₃The magnetic iron oxide material layer adopts a mode of stacking two regular film stacks and is composed of a magnetic oxide material Fe2O3 and a low-refractive-index oxide material SiO₂Forming a first film stack of a metal oxide high refractive index material Nb₂O₅And low refractive index oxide material SiO₂Forming a second membrane stack with a basic structure of Air/2ML (ML) (HL) 3/Glass and a total membrane layer number of fourteen. The physical thickness of each material in the structure is the same or an integer multiple of the unit thickness, which is a regular thickness sequence. The film material layer structure and thickness parameters are as follows in Table 3-1.

The film stack sequence is characterized in that the film stack sequence has an extremely narrow reflection peak in a sky blue spectrum band, so that a color display effect of high-saturation sky blue is achieved, absorption rates of different layers of magnetic oxide materials and an absorption rate distribution diagram of an integral film stack structure in a visible spectrum band are shown in fig. 4-1 and 4-2, and as can be seen from the diagram, due to the characteristic of strong absorption of the magnetic oxide, the reflection bandwidth of a reflection main peak in a blue light reflection band is greatly compressed, and the high-saturation color characteristic is achieved. Fig. 4-3 are reflection curves and color rendering properties of the stack at different angles of the visible spectrum, the structure achieves an interference increase of reflectivity of up to 90% at a sky-blue band center wavelength of 470nm, and the structure effectively increases the color saturation of the material. The wavelength of the main reflection peak is 470nm in vertical observation, the wavelength of the main reflection peak is shifted to 450nm under the condition of inclining an observation angle of 30 degrees, the integral color development is dark blue, the wavelength of the main reflection peak is shifted to 41nm under the condition of inclining the observation angle of 60 degrees, an orange-red secondary reflection peak with the central wavelength of 610nm appears in a long-wave region, and the integral color development is purple red.

Example four

A magnetic controllable film structure color material changing pure red into golden yellow comprises a substrate and a multilayer interference magnetic structure color film, wherein the substrate adopts a K9 glass deposition film with the diameter of 80 mm, the thickness of 2 mm and the surface quality of 20/10. The multilayer interference magnetic structure color film comprises a full-medium transparent oxide material layer of SiO2, a metal oxide high-refractive-index material layer of Nb2O5 and a magnetic iron oxide material layer of Fe3O4, wherein the magnetic layers are inserted at two insertion positions in the film thickness sequence to be used as an absorption interference layer combined design and have magnetic response characteristics.

In this embodiment, the pure red-to-golden yellow structure is not designed according to the regular quarter-wave film stack structure as in the first and second embodiments, but a color target optimization design mode is adopted, the color is optimally designed by taking a chromaticity coordinate value (Lab) with a pure red color at a vertical observation angle, an orange-red chromaticity coordinate value (Lab) at a 30-degree observation angle and a golden yellow chromaticity coordinate value (Lab) at a 60-degree observation angle as target values, the initial structure is an Air/MLH/Glass three-layer structure, and a high-refractive-index magnetic oxide material M is Fe on the Glass₃O₄The magnetic material Fe₃O₄The layer is provided with a low-refractive-index dielectric material L of SiO₂The low refractive index dielectric material SiO₂The high-refractive-index dielectric material H is Nb₂O₅Adopting a global optimization synthesis method Needle to carry out color optimization design, wherein design variables comprise physical thickness and total layer number of the materials in the three materials, finally obtaining a thickness sequence with twelve total layer numbers, and adopting a high-refractive-index material Nb₂O₅The low refractive index material is SiO₂The magnetic layer is made of oxide material Fe₃And O. The film layers were arranged as in Table 4-1 below. The thickness sequence is arranged in a basic sequence of MLHLHLMLHLHL, the magnetic oxide materials are respectively inserted in the first layer and the seventh layer, the thickness of each material is different and can be arbitrarily combined to meet the target color value, so that the thickness sequence is irregular thickness variation.

In order to realize the pure red structural color, the reflection sub-peaks of the short-wave blue light wave band and the green wave band need to be eliminated, the short-wave absorption of the all-dielectric material in the visible light wave band is not obvious enough, and as can be seen from fig. 5-1 and fig. 5-2, with the insertion of the magnetic oxide material Fe3O4 in the first layer and the seventh layer, the absorption of the whole film in the 420-570nm wave band is obviously improved, and the absorption rate can reach 95%, which is the most critical condition for realizing the pure red. As can be seen from fig. 5-3, the structure achieves an interference increase of reflectivity up to 90% at a central wavelength of 670nm in the red band, which effectively increases the color saturation of the material. The wavelength of a main reflection peak is 670nm in vertical observation, the reflection region only covers a red region, the integral color development is pure red, the wavelength of the main reflection peak is shortened to 620nm under the condition of inclining an observation angle of 30 degrees, the reflection region only covers a large part of the red region and a small part of a yellow region, the integral color development is orange red, the wavelength of the main reflection peak is shortened to 570nm under the condition of inclining the observation angle of 60 degrees, the reflection region only covers the yellow region, and the integral color development is golden yellow.

The high absorption characteristic of the short wave of the magnetic oxide material plays a key role in compressing the short wave reflection and improving the red saturation in the structure, and simultaneously the high refractive index characteristic of the oxide material enables the material and other all-dielectric oxide materials to realize interference superposition and realizes the reflection constructive interference effect of a red wave band; finally, the magnetic oxide material Fe3O4 also has a magnetic controllable orientation function, so that the red-to-golden-yellow film structure color material has obvious optical color change characteristics, a magnetic response function and human-friendly characteristics.

As can be seen from the above embodiments, the magnetic structure color thin film material of the present embodiment is safe to human body and has high saturation, and has obvious optical color change characteristics, magnetic response function and human-friendly characteristics.

Unlike common magnetically controllable thin film materials, in the present embodiment, the metal oxide magnetic material not only serves as a magnetic functional film layer, but also serves as a high refractive index medium layer to participate in color regulation and reflectivity regulation, and the absorption type oxide magnetic thin film material has an obvious absorption effect on short waves to weaken a secondary peak, thereby increasing the saturation of color. In the traditional magnetic metal medium film structure color material, the magnetic material is used as a central insertion layer, and the magnetic material only has a magnetic function and does not have a color regulation function. The absorption response of the absorption type all-dielectric magnetic thin film material to short waves and long waves at different angles is different, so that the bandwidth of a first-order interference peak is reduced, the maximum reflectivity is not reduced, and the color saturation is increased at a large angle. Meanwhile, the iron oxide compound which is commonly existing in nature is used as a raw material, and the iron oxide compound is easy to synthesize in a laboratory. Iron and oxygen are chemically combined to form iron oxide, so that the material has the characteristics of magnetic response, environmental friendliness, human body safety and the like. The interference design of the all-dielectric material does not introduce metal as a middle reflecting layer, so that the actual interference color is kept while high metal luster is obtained, and the angle-dependent color variation performance of the material is improved.

The magnetic layer according to the present embodiment provides a magnetic response characteristic, and provides an optical illusion image having a motion characteristic according to the inclination of the image or the change in the position of the light source that is irradiated on the image. Meanwhile, the pigment flakes are ensured to have obvious optical color changing property, magnetic response function and human-friendly property.

The above description is only a preferred embodiment of the present invention, and therefore should not be taken as limiting the scope of the invention, which is defined by the appended claims and their equivalents.

Claims

1. A magnetic structural color film, characterized by: the multilayer interference magnetic structure color film comprises a magnetic non-metal medium film material layer and a non-magnetic full-medium transparent material layer, wherein the magnetic non-metal medium film material layer is made of a magnetic oxide material and has a high refractive index, and the magnetic non-metal medium film material layer is used as a magnetic functional film layer and a high refractive index medium layer capable of participating in color regulation and brightness regulation.

2. The magnetic structural color film of claim 1, wherein: the multilayer interference magnetic structure color film comprises a plurality of magnetic non-metal medium film material layers and a plurality of non-magnetic full medium transparent material layers which are alternately formed.

3. A magnetic structural color film according to claim 1 or 2, wherein: the refractive index of the magnetic oxide material in a visible spectrum wave band of 380nm-760nm is 1.8-4.0, and the extinction coefficient is 0.001-3.

4. A magnetic structural color film according to claim 1 or 2, wherein: the magnetic oxide material is at least one of iron, manganese, cobalt magnetic metal oxide or spinel ferrite based on the magnetic metal oxide or spinel ferrite material or the mixture of at least two of the materials which are friendly to human body.

5. A magnetic structural color film according to claim 1 or 2, wherein: the magnetic oxide material is at least one of ferric oxide, ferrous oxide, nickel oxide, cobalt oxide, nickel iron oxide, ferroferric oxide, manganese oxide, ferromanganese oxide and cobalt iron oxide or a mixture of at least two of the materials.

6. A magnetic structural color film according to claim 1 or 2, wherein: the refractive index of the non-magnetic all-dielectric transparent material layer is 1.3-2.6.

7. A magnetic structural color film according to claim 1 or 2, wherein: the non-magnetic full-medium transparent material layer is one of silicon dioxide, aluminum oxide, magnesium fluoride, aluminum fluoride, cerium fluoride, steel chloride, sodium aluminum fluoride, neodymium fluoride, paper money fluoride, barium fluoride, calcium fluoride, lithium fluoride, yttrium oxide, bismuth oxide, neodymium oxide, titanium dioxide, trititanium pentoxide, tantalum pentoxide, niobium pentoxide, hafnium oxide, zirconium oxide, zinc sulfide, lanthanum titanate and a mixture of at least two of the above materials.

8. A magnetic structural color film according to claim 1 or 2, wherein: the non-magnetic all-dielectric transparent material layer comprises a middle-high refractive index non-magnetic dielectric layer and a low refractive index non-magnetic dielectric layer, wherein the middle-high refractive index non-magnetic dielectric layer and the low refractive index non-magnetic dielectric layer are alternately arranged.

9. The magnetic structural color film of claim 8, wherein: the multilayer magnetic thin film material layer is dispersedly clamped between a plurality of layers of middle and high refractive index non-magnetic medium layers and low refractive index non-magnetic medium layers.

10. The magnetic structural color film of claim 1, wherein: the difference between the refractive index of the magnetic non-metal dielectric thin film material layer and the refractive index of the non-magnetic full-dielectric transparent material layer in the visible light wave band is more than or equal to 0.2.