JP2020180289A - Non-color shifting multilayer structures and protective coatings on those structures - Google Patents

Abstract

To provide a weather-resistant high-chroma omnidirectional structural color pigment.SOLUTION: An omnidirectional structural color pigment 10 having a first layer 110 of a first material and a second layer 120 of a second material, the second layer extending across the first layer. The pigment reflects a band of electromagnetic radiation having a predetermined full width at half maximum (FWHM) of less than 300 nm and a predetermined color shift of less than 30° when the pigment is exposed to broadband electromagnetic radiation and viewed from angles between 0 and 45°. The pigment has a weather resistant coating, which covers an outer surface of the pigment and reduces a photocatalytic activity of the pigment by at least 50% relative to the pigment not having the weather resistant coating.SELECTED DRAWING: Figure 24

Description

The present invention relates to a multilayer thin film structure having a protective coating, and in particular, a multilayer thin film structure having a protective coating that exhibits minimal or unrecognizable color shift when viewed from various angles when exposed to wideband electromagnetic radiation. ..

<Cross-reference of related applications>
This application is a partial continuation application (CIP) of U.S. Patent Application No. 14 / 242,429 filed April 1, 2014, which is further U.S. Patent Application No. 14 / filed December 23, 2013. The CIP of No. 138,499, which is further the CIP of U.S. Patent Application No. 13 / 913,402 filed June 8, 2013, which is further the CIP of U.S. Patent Application No. 13/913, 402, filed February 6, 2013. The CIP of Application No. 13 / 760,699, which is further the CIP of U.S. Patent Application No. 13 / 57,071 filed on August 10, 2012, which is further dated February 5, 2012. The CIP of U.S. Patent Application No. 13 / 021,730 of the application, which is also U.S. Patent Application No. 112 / 793,772 filed June 4, 2010 (US Pat. No. 8,736,959). Is the CIP of U.S. Patent Application No. 12 / 388,395 (U.S. Pat. No. 8,749,881) filed February 18, 2009, which is also the CIP of U.S. Pat. No. 8,749,881. This is the CIP of US Patent Application No. 11 / 837,529 (US Pat. No. 7,903,339) filed on 12th May. U.S. Patent Application No. 13 / 913,402, filed June 8, 2013, is the CIP of U.S. Pat. No. 13,014,398 filed January 26, 2011, which is further June 4, 2010. CIP of US Pat. No. 12,793,772 filed in Japan. U.S. Patent Application No. 13/014,398 filed January 26, 2011 is the CIP of U.S. Patent No. 12 / 686,861 filed January 13, 2010, which is further dated February 19, 2009. CIP of US Pat. No. 12 / 389,256 of the application (US Pat. No. 8,329,247), all of which are incorporated by reference in their entirety.

Pigments made from multi-layer laminates are known. In addition, pigments that exhibit or provide highly saturated omnidirectional structural colors are also known. However, pigments of known art such as these required as many as 39 thin film layers in order to obtain the desired color properties.

It should be understood that the cost of producing a thin film multilayer pigment is proportional to the number of layers required. Therefore, the cost of producing a highly saturated omnidirectional structural color using a multilayer laminate of dielectric materials can be very high. Therefore, a highly saturated omnidirectional structural color that requires a minimal thin film layer is desirable.

In addition to the above, it should be understood that pigments may fade, discolor, etc. when exposed to sunlight, and especially ultraviolet light. Therefore, a weather-resistant, high-saturation omnidirectional structural color pigment is further required.

Provided is an omnidirectional structural color pigment having a protective coating. The pigment has a first layer of the first material and a second layer of the second material, the second layer extending over the first layer. In addition, when the pigment is exposed to wideband electromagnetic radiation and observed from an angle between 0 ° and 45 °, the pigment has a given full width at half maximum (FWHM) less than 300 nm and a given color less than 30 °. Reflects the band of electromagnetic radiation with deviation. In addition, the pigment has a weather resistant coating that coats its outer surface and reduces the relative photocatalytic activity of the pigment by at least 50%.

The weather resistant coating can include an oxide layer, which can be selected from silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, and / or cerium oxide. In addition, the weather resistant coating can include a first oxide layer and a second oxide layer, the second oxide layer being different from the first oxide layer. Further, the second oxide layer may be a mixed oxide layer which is a combination of at least two different oxides. Finally, the pigment itself, i.e., except for the protective coating, has no oxide layer.

Further disclosure of methods for producing omnidirectional structural color pigments with protective coatings. The method comprises supplying a plurality of pigment particles having the above-mentioned structure and properties, and suspending the plurality of pigment particles in a first liquid to form a pigment suspension. In addition, it supplies a second liquid and oxide precursors containing oxide constituent elements such as silicon, aluminum, zirconium, titanium, or cerium. Mixing this pigment suspension with an oxide precursor results in a precipitate of multiple pigment particles with a weather resistant oxide coating, which gives the pigment a relative photocatalytic activity of at least 50. % Decrease.

In some examples, the first liquid is the first organic solvent and the second liquid is the second organic solvent. Further, the first and second organic solvents may be organic polar solvents such as n-propyl alcohol, isopropyl alcohol, ethanol, n-butanol, and acetone. In another example, the first organic solvent and the second organic solvent may be polar protonic organic solvents.

With respect to the oxide precursor, the oxide constituent element silicon may be in the form of tetraethoxysilane, and the oxide constituent element aluminum may be at least aluminum sulfate and aluminum-tri-sec-butoxide. It may be in one form, and the oxide constituent element zirconium may be in the form of zirconium butoxide, and the oxide constituent element cerium is at least one of cerium nitrate hexahydrate and cerium sulfate. Titanium, which may be in one form and is an oxide constituent element, may be in at least one form of titanium ethoxydo, titanium isopropoxide, and titanium butoxide.

In another example, the first liquid is the first aqueous liquid and the second liquid is the second aqueous liquid. Further, the oxide constituent element silicon may be in the form of sodium silicate, and the oxide constituent element aluminum may be in the form of at least one of aluminum sulfate, aluminum sulfate hydrate, and sodium aluminate. The oxide constituent element, zirconium, may be in the form of zirconium chloride octahydrate, and the oxide constituent element, cerium, may be in the form of cerium sulfate hexahydrate. The oxide constituent element, titanium, may be in the form of titanium tetrachloride.

FIG. 1A is a schematic diagram of a dielectric layer (DL) that reflects or transmits incident electromagnetic radiation. FIG. 1B is a schematic diagram of a reflector layer (RL) reflecting incident electromagnetic radiation. FIG. 1C is a schematic diagram of an absorber layer (AL) absorbing incident electromagnetic radiation. FIG. 1D is a schematic representation of a selective absorber layer (SAL) that reflects, absorbs, and transmits incident electromagnetic radiation. FIG. 2 is a schematic diagram of reflection and transmission of incident electromagnetic radiation by a first generation omnidirectional structural color multilayer thin film made of a plurality of dielectric layers. FIG. 3 is a schematic diagram of a first generation omnidirectional structural color multilayer thin film made of a plurality of dielectric layers. FIG. 4 is a graph showing a comparison of 0.2% range vs. midrange percentages for TM and TE modes of electromagnetic radiation. FIG. 5 is a reflectance graph as a function of wavelength for Case 2 shown in FIG. FIG. 6 is a graph showing the scattering of the center wavelengths in cases 1, 2 and 3 shown in FIG. FIG. 7 is a schematic diagram of reflection and absorption of incident electromagnetic radiation by a second generation omnidirectional structural color multilayer thin film made of a plurality of dielectric layers and one absorber layer. FIG. 8 is a schematic representation of a second generation omnidirectional structural color multilayer thin film made of a plurality of dielectric layers, an absorber layer, and / or a reflector layer. FIG. 9A shows a second generation 5 made of a plurality of dielectric layers and absorber / reflector layers having a saturation (C *) of 100 and a reflectance (maximum reflectance) of 60%. It is a schematic diagram of a layer omnidirectional structural color multilayer thin film. FIG. 9B shows the second generation five-layer omnidirectional structural color multilayer film shown in FIG. 9A as compared with the first generation 11-layer omnidirectional structural color multilayer thin film observed from an angle between 0 ° and 45 °. It is a graph of reflectance vs. wavelength of a thin film. FIG. 10 is a schematic representation of a third generation omnidirectional structural color multilayer thin film made from a dielectric layer, a selective absorber layer (SAL), and a reflector layer. FIG. 11A is a schematic representation of zero or near zero electric field points in a ZnS dielectric layer exposed to electromagnetic radiation (EMR) having a wavelength of 500 nm. FIG. 11B shows the absolute value of the square of the electric field (| E | ² ) vs. the thickness of the ZnS dielectric layer shown in FIG. 1A when exposed to EMR having wavelengths of 300 nm, 400 nm, 500 nm, 600 nm, and 700 nm. It is a graph of. FIG. 12 is a schematic view of a dielectric layer that extends over a substrate or reflector layer and is exposed to electromagnetic radiation at an angle θ from the vertical direction of the outer surface of the dielectric layer. FIG. 13 is a schematic diagram of a ZnS dielectric layer in which a Cr absorber layer is arranged at a zero or almost zero electric field point in the ZnS dielectric layer with respect to EMR having a wavelength of 434 nm. FIG. 14 shows a reflection percentage vs. reflection EMR when a multilayer laminate without a Cr absorber layer (eg, FIG. 1A) and a multilayer laminate with a Cr absorber layer (eg, FIG. 3A) are exposed to white light. It is a graph of wavelength. FIG. 15A is a graph of the first harmonic and the second harmonic represented by the ZnS dielectric layer (eg, FIG. 4A) extending over the Al reflector layer. In FIG. 15B, the Cr absorber layer is arranged in the ZnS dielectric layer so that the ZnS dielectric layer extends over the Al reflector layer and the second harmonic shown in FIG. 8A is absorbed. It is a graph of the reflection percentage vs. EMR wavelength for a multilayer laminate. In FIG. 15C, the ZnS dielectric layer extends over the Al reflector layer, and the Cr absorber layer is arranged in the ZnS dielectric layer so that the first harmonic shown in FIG. 8A is absorbed. , Is a graph of reflection percentage vs. EMR wavelength for a multilayer laminate. FIG. 16A is a graph of the thickness of the square-to-dielectric layer of the electric field, showing the angular dependence of the electric field of the Cr absorber layer on exposure to incident light from angles between 0 ° and 45 °. FIG. 16B shows the% absorption rate vs. reflected EMR wavelength by the Cr absorber layer when exposed to white light from an angle between 0 ° and 45 ° with respect to the perpendicular to the outer surface (0 ° to the perpendicular to the surface). It is a graph of. FIG. 17A is a schematic view of a red omnidirectional structural color multilayer laminate based on an embodiment of the present invention. FIG. 17B is a graph of reflected EMR wavelengths for exposure to white light from an angle between 0 ° and 45 ° with respect to the% absorption of the Cu absorber layer shown in FIG. 10A versus the multilayer laminate shown in FIG. 10A. is there. FIG. 18 shows the reflectance% vs. reflection EMR wavelength between the calculated / simulated data and the experimental data to prove the concept of the red omnidirectional structural color multilayer laminate when exposed to white light from an angle of 0 °. It is a comparison graph. FIG. 19 is a graph of reflectance% vs. wavelength for an omnidirectional structural color multilayer laminate based on an embodiment of the present invention. FIG. 20 is a graph of reflectance% vs. wavelength for an omnidirectional structural color multilayer laminate based on the embodiment of the present invention. FIG. 21 is a graph of reflectance% vs. wavelength for an omnidirectional structural color multilayer laminate based on the embodiment of the present invention. FIG. 22 is a graph of reflectance% vs. wavelength for an omnidirectional structural color multilayer laminate based on the embodiment of the present invention. FIG. 23 shows a * b using the CIELAB color space, comparing saturation and hue shifts between conventional paints and paints (sample (b)) made from pigments based on embodiments of the present invention. * It is a graph showing a part of the color map. FIG. 24 is a schematic view of an omnidirectional structural color multilayer laminate based on an embodiment of the present invention. FIG. 25 is a schematic view of an omnidirectional structural color multilayer laminate based on an embodiment of the present invention. FIG. 26 is a schematic view of an omnidirectional structural color multilayer laminate based on an embodiment of the present invention. FIG. 27 is a schematic view of a four-layer omnidirectional structural color pigment based on an embodiment of the present invention. FIG. 28 is a schematic diagram of a 7-layer omnidirectional structural color pigment based on an embodiment of the present invention. FIG. 29 is a schematic diagram of an 11-layer omnidirectional structural color pigment having a protective coating based on an embodiment of the present invention. FIG. 30 is a schematic representation of a protective coating comprising two or more layers based on an embodiment of the present invention. FIG. 31 is a plot graph of the normalized relative photocatalytic activity of omnidirectional structural color pigments with several protective coatings. FIG. 32A is one of a pair of scanning electron microscope (SEM) images for a plurality of seven-layer omnidirectional structural color pigments without a protective coating. FIG. 32B is one of a pair of scanning electron microscope (SEM) images of a plurality of seven-layer omnidirectional structural color pigments with a protective coating of silicon oxide and zirconium oxide-aluminum oxide.

Provides omnidirectional structural colors. This omnidirectional structural color reflects a narrow band of electromagnetic radiation in the visible spectrum when observed from an angle between 0 ° and 45 °, and has a small or indistinguishable color shift. It has a form of (also referred to as a multilayer laminate in the specification). This multilayer thin film can be used for pigments in paint compositions, continuous thin films on structures, and the like.

The multilayer thin film includes a multilayer laminate having a first layer and a second layer extending over the first layer. In some examples, the multilayer laminate reflects a narrow band of electromagnetic radiation having a FWMH of less than 300 nm, more preferably less than 200 nm, and in some cases less than 150 nm. When the multilayer thin film is exposed to wideband electromagnetic radiation, for example, white light and observed from an angle between 0 ° and 45 °, the multilayer thin film is smaller than 50 nm, more preferably smaller than 40 nm, still more preferably 30 nm. It also has a smaller color shift. Further, the multilayer laminate may or may not have separate reflection bands of electromagnetic radiation in the UV and / or IR regions.

The total thickness of this multilayer laminate is smaller than 2 μm, preferably smaller than 1.5 μm, and even more preferably smaller than 1.0 μm. Therefore, the multilayer laminate can be used as a paint pigment for a thin layer paint coating.

The first and second layers can be made from a dielectric material, and alternatives the first and / or second layers can be made from an absorber material. Absorbent materials include selective absorber materials such as Cu, Au, Zn, Sn, alloys thereof, and the like, or alternative, colored dielectric materials such as Fe ₂ O ₃ , Cu ₂ O, these. Combinations of, and similar ones are included. The absorber material further comprises a non-selective absorbent material such as Cr, Ta, W, Mo, Ti, Ti nitride, Nb, Co, Si, Ge, Ni, Pd, V, ferric oxide, a combination thereof or It may be an alloy and the same kind. The thickness of this absorber layer made from the selective absorber material is between 20-80 nm, whereas the thickness of the absorber layer made from the non-selective absorber material is 5-30 nm.

The multilayer laminate further includes a reflector layer in which a first layer and a second layer extend over the first layer, and the reflector layer is, for example, Al, Ag, Pt, Cr, Cu, Zn, Au. , Sn, made from materials such as these alloys and the like. This reflector layer usually has a thickness between 30 and 200 nm.

The multilayer stack may have a narrow reflection band of electromagnetic radiation having a symmetric peak morphology in the visible spectrum. Alternatively, the reflection narrow band of electromagnetic radiation in the visible spectrum can be adjacent to the UV region, so that part of the reflection band of electromagnetic radiation, the UV portion, is invisible to the human eye. .. Alternatively, the reflection band of electromagnetic radiation can have a portion thereof in the IR region, whereby the IR portion is also invisible to the human eye.

Regardless of whether the reflection band of this electromagnetic radiation in the visible spectrum is adjacent to the UV and IR regions or has a symmetric peak in the visible spectrum, the multilayer thin films disclosed herein are: It has a narrow reflection band of electromagnetic radiation in the visible spectrum, with low, small or unrecognizable color shifts. This low or unrecognizable color shift may be in the form of a small shift in the central wavelength of the reflection narrow band of electromagnetic radiation. Alternatively, the low or unrecognizable color shift may be in the form of a small shift at the UV or IR side of the reflection band of electromagnetic radiation adjacent to the IR or UV region, respectively. When observing the multilayer thin film from an angle between 0 ° and 45 °, such small shifts at the center wavelength, UV side edges, and / or IR side edges are usually less than 50 nm, and in some examples. Is less than 40 nm, and in other examples less than 30 nm.

In addition to the above, this omnidirectional structural color in the form of a multilayer thin film may be in the form of a plurality of pigment particles with a protective coating. Thereby, a weather resistant pigment can be provided. The protective coating can include one or more oxide layers that reduce the relative photocatalytic activity of the pigment particles. The oxide layer may be any oxide layer known to those skilled in the art, and examples thereof include a silicon oxide layer, an aluminum oxide layer, a zirconium oxide layer, a titanium oxide layer, a cerium oxide layer, a combination thereof, and the same kind. Can contain things. In some examples, the protective coating comprises a first oxide layer and a second oxide layer. Further, the first oxide layer and / or the second oxide layer may be a mixed oxide layer, that is, an oxide layer which is a combination of two kinds of oxides. Furthermore, as described above, the pigment itself may be in the form of a multilayer thin film containing no oxide layer.

Methods for producing omnidirectional structural color pigments may or may not include the use of acids, acidic compounds, acidic solvents, and the like. In other words, the plurality of omnidirectional structural color pigment particles may or may not be treated with an acidic solvent. Further teaching and details of the omnidirectional structural color pigment and the method for producing the pigment will be described later in the present specification.

Referring to FIG. 1, FIGS. 1A-D represent the basic components of an omnidirectional structural color design. In particular, FIG. 1A shows a dielectric layer exposed to incident electromagnetic radiation. Further, the dielectric layer (DL) reflects a part of the incident electromagnetic radiation and transmits the other part. In addition, the incident electromagnetic radiation is equal to the transmitted and reflected parts, and the transmitted parts are usually sufficiently larger than the reflected parts. The dielectric layer is made of a dielectric material such as SiO ₂ , TiO ₂ , ZnS, MgF ₂ , and the like.

As a clear symmetry, FIG. 1B represents a reflector layer (RL) in which all incident electromagnetic radiation is reflected and the transmittance is essentially zero. The reflector layer is usually made of materials such as aluminum, gold, and the like.

FIG. 1C shows an absorber layer (AL) in which incident electromagnetic radiation is absorbed by this layer and is not reflected or transmitted. Such an absorber layer is made, for example, from graphite. In addition, all incident electromagnetic radiation is absorbed, and transmission and reflection are about zero.
FIG. 1D represents a selective absorber layer (SAL) in which some of the incident electromagnetic radiation is absorbed by this layer, some is transmitted, and some is reflected. Therefore, the amount of electromagnetic radiation that is transmitted, absorbed, and reflected is equal to the amount of incident electromagnetic radiation. In addition, such selective absorber layers can be made from thin layers of chromium, layers of copper, brass, and bronze, as well as materials such as the like.

The present invention discloses the design and manufacture of three generations of omnidirectional structural color thin layers.

<1st generation>
With reference to FIG. 2, a schematic diagram of a multilayer thin film having a plurality of dielectric layers is shown. In addition, the reflection and transmission of incident electromagnetic radiation is schematically shown. As mentioned above, the normal transmission of incident electromagnetic radiation is much greater than the reflection on it, thus requiring more layers.

FIG. 3 shows a portion of a multilayer thin film made of a dielectric layer having a _first refractive index (DL ₁ ) and a second refractive index (DL ₂ ). It should be understood that the double lines between layers merely indicate the boundaries between different layers.

Some design and manufacturing methods or means for obtaining the desired multilayer laminate, but not limited by principle, are as follows.

When electromagnetic radiation hits the surface of a material, the waves of this radiation are reflected or transmitted from the material. Further, when the electromagnetic wave collides with the first terminal 12 of the multilayer laminate 10 at an angle θ ₀ , the reflection angles of the electromagnetic wave to the surfaces of the layer having a high refractive index and the surface of the layer having a low refractive index are θ _H and θ _L , respectively. is there. Using Snell's law,
If the refractive indexes n _H and n _L are known, the angles θ _H and θ _L can be determined.

For omnidirectional reflectance, the maximum refraction angle (θ _{H, Max} ) in the first layer is the first layer and the second layer as a necessary but insufficient condition of the TE mode and TM mode of electromagnetic radiation. Must be less than the Blue Star angle (θ _B ) of the interface between the layers of. If this condition is not met, the TM mode of electromagnetic radiation will not reflect at the second and subsequent interface and will therefore pass through this structure.
Using this consideration,
as well as
Therefore, the following is required:

In addition to the requirements expressed by Equation 4, the electromagnetic waves of wavelength λ are directed towards the multi-layer structure at an angle θ0, and the individual bilayers of the multi-layer structure have a thickness d _H and n _L with refractive indexes n _H and n _L , respectively. When having d _L , the characteristic conversion matrix ( _FT ) is expressed as follows.
This can also be expressed as:
here:
as well as
Is.
further,
here,
as well as
Is.
Clearly solving ρ _T for TE and TM:
as well as

The viewing angle-dependent band structure can be obtained from the boundary conditions for the ends of the total internal reflection region, also known as the band ends. For the purposes of the present invention, the band edge is defined as a line equation that separates the total reflection region from the transmission region for a given band structure.

The boundary conditions that determine the band frequency of the high reflection band are given by the following conditions.
Therefore, from Equation 3:
Or in another way:
Combining equations 15 and 7 gives the following band-end equation:
here:
as well as:
The + symbol in the above band end equation represents the band end for _long wavelengths (λ _long ), and the-symbol represents the band end for short wavelengths (λ _short ).
Reorganizing equations 20 and 21:
About TE mode:
as well as,
About TM mode:
Is.

The approximate solution of the band edge can be determined by the following expression:
Given the quarter-wavelength design (described in more detail below) and the optical thickness of the alternating layers selected to be equal to each other, this approximation is valid. Moreover, if the optical thickness of the alternating layers is relatively small, the cosine approaches 1. In this way, equations 23 and 24 result in an approximate band-end equation:
About TE mode:
And about TM mode:

The values of L + and pTM as a function of the angle of incidence can be obtained from equations 7, 8, 14, 15, 20, and 21 thereby for λlong and λshort in TE and TM modes as a function of the angle of incidence. Calculation is possible.

The center wavelength (λc) of the omnidirectional reflector is:
It can be determined by the relational expression of.
The center wavelength can be an important parameter because its value suggests a long and / or approximate range of the reflected electromagnetic wave spectrum. Another important parameter that can provide implications for the width of the reflection band is defined as the range of wavelengths within the omnidirectional reflection band to the midrange ratio of wavelengths within the omnidirectional reflection band. This "range to midrange ratio" (η) is mathematically expressed as:
About TE mode
About TM mode:
The range to midrange ratio can be expressed as a percentage, and it should be understood that the terms "range to midrange ratio" and "range to midrange ratio percentage" are used synonymously for the purposes of the present invention. Further, it should be understood that the value of "range to midrange ratio" presented with the "%" symbol is the value of the percentage of "range to midrange ratio". The values of the "range to midrange ratio" in TM mode and TE mode can be calculated numerically from equations 28 and 29 and can be plotted as a function of high index and low index.

It should be understood that the dispersion of the central wavelength must be minimized in order to obtain a narrow omnidirectional band.

Therefore, from Equation 27, the variance of the center wavelength is:
Can be expressed as:
here:
The central wavelength dispersion factor F _c can be expressed as:

From the above, the multilayer laminate having the desired low center wavelength shift (Δλ _c ) has a refractive index of n _L , and one or more layers have a thickness d _L, and a low refractive index material and n _H. It has a refractive index of, and can be designed from the high refractive index material one or a plurality of layers have a thickness d _H.

In particular, FIG. 4 is a graph comparing the 0.2% range-to-midrange ratios of electromagnetic radiation in TM mode and TE mode plotted as a function of high refractive index vs. low refractive index. As shown in the figure, three cases are shown, Case I relates to a large difference between TM mode and TE mode, Case II relates to a case where the difference between TM mode and TE mode is small, and Case III relates to a case. It relates to the case where the difference between the TM mode and the TE mode is very small. In addition, FIG. 5 represents the reflectance percent vs. wavelength of the reflected electromagnetic radiation for a similar case in Case II.

As shown in FIG. 5, scattering with a small center wavelength is shown for the multilayer thin film corresponding to Case III. In addition, when the multilayer thin film is observed from an angle between 0 ° and 45 ° in combination with the reference with respect to FIG. 6, Case 2 causes a color shift smaller than the center wavelength of 50 nm (Case II), and the multilayer is multilayer. When the thin film is observed from an angle between 0 ° and 45 °, Case III results in a color shift smaller than the center wavelength of 25 nm (Case III).

<2nd generation>
With reference to FIG. 7, an exemplary structure / design based on the second generation is shown. The multilayer laminate shown in FIG. 7 has a plurality of dielectric layers and an absorber layer under the dielectric layer. In addition, none of the incident electromagnetic radiation is transmitted through this structure, that is, all incident electromagnetic radiation is reflected or absorbed. Such a structure, as shown in FIG. 7, makes it possible to reduce the number of dielectric layers required to obtain a sufficient amount of reflection.

For example, FIG. 8 shows a multilayer laminate extending over a central absorber layer made of Cr, a first dielectric material layer (DL ₁ ) extending over a Cr absorber layer, and a DL ₁ layer. It provides a schematic representation of such a structure with a second dielectric material layer (DL ₂ ) and a DL ₁ layer extending over the DL ₂ layers. In such a design, the thickness of the first dielectric layer and the third dielectric layer may be the same or different.

In particular, FIG. 9A shows a graphical representation of the structure in which the central Cr layer is coupled to _two TiO ₂ layers, which are further coupled by two SiO ₂ layers. As shown by the plot, the layers of TiO ₂ and SiO ₂ are not equal in thickness. In addition, FIG. 9B shows a reflectance vs. wavelength spectrum comparing the 5-layer structure shown in FIG. 9A with the 13-layer structure based on the first generation design. As shown in FIG. 9B, when this structure is observed from an angle between 0 ° and 45 °, it results in a shift of the center wavelength less than 50 nm, preferably less than 25 nm. The fact that the 5-layer structure based on the 2nd generation behaves essentially the same as the 13-layer structure of the 1st generation is further shown in FIG. 9B.

<3rd generation>
Referring to FIG. 10, the lower reflector layer (RL) has a first dielectric material layer DL ₁ extending over it and a selective absorber layer SAL extending over DL ₁ layer. , 3rd generation design is shown. In addition, another DL1 layer may or may not be provided and may or may not extend over the selective absorber layer. A diagram in which all incident electromagnetic radiation is reflected or selectively absorbed by the multilayer stack is further shown in the figure.

Such a design, as shown in FIG. 10, corresponds to different schemes used to design and manufacture the desired multilayer laminate. In particular, the thickness of the zero or near zero electric field points of the dielectric layer is utilized and discussed below.

For example, FIG. 11A is a schematic diagram of a ZnS dielectric layer extending over the Al reflector layer. The ZnS dielectric layer has a zero or near zero electric field point at 77 nm for incident electromagnetic radiation having a total thickness of 143 nm and a wavelength of 500 nm. In other words, the ZnS dielectric layer has a zero or near zero electric field point at a distance of 77 nm from the Al reflector layer for an incident EMR having a wavelength of 500 nm. In addition, FIG. 11B provides a graph of the electric field over the ZnS dielectric layer for different EMR wavelengths. As shown in the graph, the dielectric layer has zero or near zero electric field points at a thickness of 77 nm for incident EMRs with wavelengths of 500 nm, but for incident EMRs with wavelengths of 400 nm, 600 nm, and 700 nm. Has no or near zero electric field points.

In reference to the calculation of zero or near zero electric field points, FIG. 12 shows the total thickness “D,” increasing thickness “d”, and reflectance “n” on the substrate or central layer 2 having reflectance n _s . Represents the dielectric layer 4 having. The incident light hits the outer surface 5 of the dielectric layer 4 at an angle θ with respect to the line 6 perpendicular to the outer surface 5 and is reflected from the outer surface 5 at the same angle. The incident light passes through the outer surface 5 and enters the dielectric layer 4 at an angle θ _F with respect to the line 6 and hits the surface 3 of the base layer at an angle θ _s .

For one dielectric layer, when θs = θF and the electric field / electric field (E) is z = d, it can be expressed as E (z).
From Maxwell's equations, the electric field is about s polarization:
And p-polarized light:
Therefore, regarding s polarization,
And p-polarized light
Is.

It should be understood that the change in the electric field of the dielectric layer 4 in the z-axis direction can be estimated by calculating the unknown parameters u (z) and v (z) expressed as follows.
About s polarization q _s = n _s cos θ _s (39)
About p-polarized light q _s = n _s / cos θ _s (40)
About s polarization q = ncosθ _F (41)
About p-polarized light q = n / cosθ _F (42)
φ = k · n · dcos (θ _F ) (43)
u (z) and v (z) can be expressed as:
as well as
And p-polarized light
here,
as well as

Thus, in the simple state of θ _F = 0 or vertical incident, φ = k · n · d, and α = 0:
This makes it possible to solve "d", that is, the place where the electric field in the dielectric layer is zero.

Referring to FIG. 13, the zero or near zero electric field point of the ZnS dielectric layer shown in FIG. 11A when exposed to EMR having a wavelength of 434 nm is at 70 nm (instead of 77 nm for a wavelength of 500 nm). Equation 52 was used to calculate that. In addition, a Cr absorber layer with a thickness of 15 nm is inserted from the Al reflector layer to a thickness of 70 nm, which gives a ZnS-Cr boundary with a zero or near zero electric field. Thus, the structure of the invention allows light having a wavelength of 434 nm to pass through the Cr-ZnS boundary, but absorbs light not having a wavelength of 434 nm. In other words, this Cr-ZnS boundary has a zero or near zero electric field for light having a wavelength of 434 nm, which allows light at 434 nm to pass through this boundary. However, since the Cr-ZnS boundary does not have a zero or near zero electric field for light that does not have a wavelength of 434 nm, such light is absorbed by the Cr absorber layer and / or the Cr-ZnS boundary and is an Al reflector. Not reflected by the layer.

It should be understood that a few percent of the desired light within +/- 10 nm at 434 nm passes through the Cr-ZnS boundary. However, it should be further understood that such a narrow band of reflected light, such as 434 +/- 10 nm, still provides a vivid structural color to the human eye.

The result of having a Cr absorber layer in the multilayer laminate of FIG. 13 is shown in FIG. 14 where the wavelength of reflectance percent vs. reflection EMR is shown. Corresponding to the ZnS dielectric layer shown in FIG. 13 which does not have a Cr absorber layer, as shown by this dotted line, a narrow reflection peak is present at about 400 nm, but a wider peak is at about 500 + nm. Exists. In addition, a large amount of light is still reflected in the wavelength region of 500 nm. Therefore, there are two peaks that prevent the multilayer laminate from providing structural color.

In contrast, the solid line in FIG. 14 corresponds to the structure shown in FIG. 13 in which the Cr absorber layer is present. As shown in the figure, there is a sharp peak at about 434 nm and a sharp drop in reflectance for wavelengths greater than 434 nm is provided by the Cr absorber layer. It should be understood that the sharp peaks indicated by the solid lines appear as visually vivid / structural colors. In addition, FIG. 14 shows where the reflected peak or bandwidth is measured, i.e. the bandwidth is 50% reflectance of the maximum reflection wavelength, also known as full width at half maximum (FWHM). It is measured in the part of.

Speaking of the omnidirectional action of the multilayer laminate shown in FIG. 13, this thickness of this ZnS dielectric layer can be designed or determined, which results in only the first harmonic of reflected light. It should be understood that this is sufficient for the "blue" color, but further consideration is needed to bring about the "red" color. For example, for red, non-angle-dependent adjustments are difficult because they require a thicker dielectric layer, which results in a high harmony design, i.e. the second and desired third harmonics. The waves are inevitable. Moreover, the dark brown space is very narrow. Therefore, the red multilayer laminate has a high angular change.

To overcome this high angular variation of red, the present application discloses a design / structure that results in a unique, novel, angle-independent red. For example, FIG. 15A represents a dielectric layer that exhibits first and second harmonics with respect to incident white light when the outer surface of the dielectric layer is observed when observed from an angle of 0 ° to 45 °. .. As shown in this graph, low angular dependence (small Δλ _c ) is provided by the thickness of the dielectric layer, but such multilayers are blue (first harmonic) and red (second harmonic). It has a combination of harmonics) and is therefore not suitable for the desired "red only" color. Therefore, this theory / structure has been developed to utilize the absorber layer to absorb a group of unwanted harmonics. FIG. 15A shows the position of the center wavelength (λ _c ) of the reflection band with respect to a given reflection peak, and the dispersion or shift (Δλ _c) of this center wavelength when the sample is viewed from an angle between 0 ° and 45 °. ) Is further expressed.

With reference to FIG. 15B, the second harmonic shown in FIG. 15A is absorbed by the Cr absorber layer at the appropriate dielectric layer thickness (eg 72 nm), resulting in a crisp blue color. More importantly in the present invention, FIG. 15C provides a red color by absorbing the first harmonic at different dielectric layer thicknesses (eg 125 nm) depending on the Cr absorber layer. However, FIG. 15C further shows that the use of the Cr absorber layer is more angle dependent than desired for this multilayer laminate, i.e. greater than the desired Δλ _c .

The relatively large shifts for red compared to blue are that this dark red color space is very narrow and that the Cr absorber layer absorbs the color corresponding to the non-zero or near-zero electric field, that is, this. It should be understood by the fact that it does not absorb light when the electric field is zero or near zero. Therefore, FIG. 16A shows that this zero or near zero electric field point with respect to the light wavelength differs depending on the angle of incidence. Such factors result in the angle-independent absorbency shown in FIG. 16B, i.e., the difference in absorption rate curves at 0 ° and 45 °. Therefore, in order to further improve the design of the multilayer laminate and the angle-independent performance, for example, an absorber layer that absorbs blue light is used regardless of whether the electric field is zero or not.

In particular, FIG. 17A shows a multilayer laminate in which a Cu absorber layer extends over the ZnS layer instead of the Cr absorber layer. The results of using such a "colored" or "selective" absorber layer are shown in FIG. 17B, which is more "" of the 0 ° and 45 ° absorption rate lines of the multilayer laminate shown in FIG. 17A. It represents a "strict" grouping. Therefore, a comparison between FIGS. 16B and 16B shows that there is a significant improvement in the angle independence of absorption rates by using the selective absorber layer instead of the non-selective absorber layer. ing.

Based on the above, a multilayer structure for proving the concept was designed and manufactured. In addition, the calculation / simulation results for the sample to prove the concept and the actual experimental data were compared. In particular, as also shown in the graph plot of FIG. 18, a clear red color is obtained (wavelengths greater than 700 nm are usually invisible to the human eye), and calculations / simulations and experiments obtained from actual samples. Very good agreement was obtained with the light data of. In other words, the calculation / simulation can be used to simulate or simulate the results of a multilayer design of one or more embodiments of the invention and / or known multilayers.

A list of samples of the multilayer laminates simulated and / or actually produced is provided in Table 1 below. As shown in the table, the design of the invention disclosed herein includes at least five different layer structures. In addition, this sample was simulated and / or prepared from a large area of material. It resulted in a sample with high saturation, low color shift and perfect reflectance. In addition, the 3 and 5 layer samples have a total thickness between 120 and 200 nm; the 7 layer sample has a total thickness of 350 to 600 nm; the 9 layer sample has a total thickness of 440 to 500 nm. The 11-layer sample had a total thickness of 600-660 nm.

Reference to FIG. 19 shows a plot of reflectance percent vs. reflected EMR wavelengths for an omnidirectional reflector when exposed to white light from angles 0 ° and 45 ° with respect to the surface of the reflector. As shown in the plot, the 0 ° and 45 ° curves represent the very low reflectance that omnidirectional reflectors provide for wavelengths greater than 500 nm, eg less than 20%. However, this reflector provides a sharp increase in reflectance at wavelengths between 400 and 500 nm and reaches a maximum of about 90% at 450 nm, as shown by the curve. It should be understood that the part or region of the graph on the left hand side (UV side) of this curve represents the UV part of the reflection band provided by this reflector.

This sharp increase in reflectance provided by this omnidirectional reflector is characterized by the IR side edge of each curve extending from a low reflectance portion at a wavelength greater than 500 nm to a high reflectance portion, eg, a> 70% portion. Be done. The linear portion 200 on the IR end side is tilted at an angle (β) greater than 60 ° with respect to the x-axis, and has a length L of about 50 and a tilt of 1.2 on the reflectance axis. In one example, the linear portion is tilted at an angle greater than 70 ° with respect to the x-axis, while in other examples β is greater than 75 °. Further, the reflection band has a visible FWMH smaller than 200 nm, in some cases a visible FWMH smaller than 150 nm and in another example a visible FWMH smaller than 100 nm. In addition, the central wavelength λ _c of the visible reflection band as shown in FIG. 19 is defined as a wavelength equal to the IR side end of the reflection band and the UV end of the UV spectrum of the visible FWHM.

The term "visible FWHM" refers to the width of the reflection band between the IR end of this curve and beyond this the reflection provided by the omnidirectional reflector is at the end of the UV spectral region, which is invisible to the human eye. Please understand that it refers to. As such, the designs and multilayers of the invention disclosed herein use invisible UV moieties of electromagnetic radiation to provide a vivid structural color. In other words, despite the fact that the reflector reflects a wider band of electromagnetic radiation that extends into the UV region, the omnidirectional reflectors disclosed herein provide a narrow band of reflected visible light. In order to do so, the invisible UV part of the electromagnetic radiation spectrum is used.

With reference to FIG. 20, the overall contrasting reflection bands provided when observing the multilayer laminate according to the embodiment of the present invention from 0 ° and 45 ° are shown. As shown in the figure, the reflection band provided when the multilayer laminate based on the embodiment of the present invention is observed from 0 ° is smaller than 50 nm when the multilayer laminate is observed from 45 ° (λ _c (45 ^o )). It has a color shift of the center wavelength (λ _c (0 ^o )), that is, Δλ _c (0-45 ^o ) <50 nm. In addition, the FWMH of the 0 degree reflection band and the 45 ° reflection band is smaller than 200 nm.

FIG. 21 shows a plot of reflectance percent vs. reflected EMR wavelengths for another omnidirectional reflector design when exposed to white light from 0 ° and 45 ° angles to the surface of this reflector. There is. Similar to FIG. 19, and as shown in the plot, the 0 ° and 45 ° curves provide very low reflectance, eg, less than 10%, that this omnidirectional reflector provides for wavelengths smaller than 550 nm. Shown. However, this reflector provides a sharp increase in reflectance at wavelengths between 560 and 570 nm and reaches a maximum of about 90% at 700 nm, as shown by the curve. It should be understood that the part or region of the graph on the right hand side (IR side) of this curve represents the IR part of the reflection band provided by this reflector.

This sharp increase in reflectance provided by this omnidirectional reflector is characterized by the UV side edge of each curve extending from a low reflectance portion at a wavelength less than 550 nm to a high reflectance portion, eg, a> 70% portion. Be done. The straight portion 200 on the UV end side is tilted at an angle (β) greater than 60 ° with respect to the x-axis and has a length L of about 40 and a tilt of 1.4 on the reflectance axis. In one example, the linear portion is tilted at an angle greater than 70 ° with respect to the x-axis, while in other examples β is greater than 75 °. Further, the reflection band has a visible FWMH smaller than 200 nm, in some cases a visible FWMH smaller than 150 nm and in another example a visible FWMH smaller than 100 nm. Further, the central wavelength λ _c of the visible reflection band shown in FIG. 18 is defined as a wavelength equidistant from the UV side end of the reflection band and the IR end of the IR spectrum of the visible FWHM.

The term "visible FWHM" refers to the width of the reflection band between the UV end of this curve and beyond this the reflections supplied by the omnidirectional reflector are invisible to the human eye. Please understand that it refers to. As such, the designs and multilayers of the invention disclosed herein use invisible IR moieties of electromagnetic radiation to provide a vivid structural color. In other words, despite the fact that the reflector reflects a wider band of electromagnetic radiation extending into the IR region, the omnidirectional reflectors disclosed herein provide a narrow band of reflected visible light. In order to do so, the invisible IR part of the electromagnetic radiation spectrum is used.

Reference to FIG. 22 shows the reflectance percent vs. wavelength for another 7-layer omnidirectional reflector when exposed to white light from 0 ° and 45 ° angles to the surface of the reflector. ing. In addition, it provides a definition or evaluation of the omnidirectional properties provided by the omnidirectional reflectors disclosed herein. In particular, the central wavelength (λ _c ) defined as the wavelength at which each curve exhibits or experiences maximum reflectance, especially when the reflection band provided by the reflectors of the present invention is maximal, i.e. having peaks as shown in the figure. Has. The term maximum reflected wavelength is also used as λ _c .

As shown in FIG. 22, the outer surface of the omnidirectional reflector is at an angle of 45 ° (λ) compared to when this surface is observed at an angle of 0 ° ((λ _c (0 ^o )), that is, perpendicular to the surface. _c (45 ^o ))

For example, there is a shift or substitution of λ _c when this outer surface is viewed from an angle that appears to be tilted relatively 45 ° to the eyes of the viewer. This shift of λ _c (Δλ _c ) provides a measure of the omnidirectional properties of this omnidirectional reflector. Naturally, there is a zero shift, i.e. no shift at all, resulting in a perfect omnidirectional reflector. However, the omnidirectional reflectors disclosed herein appear to the human eye as if the surface color of the reflector has not changed, thereby making the reflector omnidirectional from a practical point of view. It is possible to provide Δλ _c of less than 50 nm. In some examples, the omnidirectional reflectors disclosed herein can provide Δλ _c less than 40 nm, in other examples less than 30 nm Δλ _c , and in others less than 20 nm Δλ. _c can be provided, and in yet even more examples, Δλ _c less than 15 nm. This shift in [Delta] [lambda] _c, the actual reflectance vs. plot of the wavelength of the reflector, and / or alternatively, if the known thickness of the material and the layer is measured by modeling the reflector be able to.

Another definition or characterization of the omnidirectional property of the reflector can be measured by a side shift of a given set of angular reflection bands. For example, also with reference to FIG. 19, observations were made from 0 ° ( _SIR (0 ^o )) compared to the IR-side edge for reflections from the same reflector observed from 45 ° ( _SIR (45 ^o )). The IR-side edge shift or substitution (ΔS _IR ) with respect to the reflection from the omnidirectional reflector provides the degree of omnidirectional properties of the omnidirectional reflector. In addition, [Delta] [lambda] _c, for example, [Delta] [lambda] _c, i.e., the reflection band (diagram a peak corresponding to the maximum reflection wavelength not in the visible region of the one to the reflector supplies a reflection band similar among shown in FIG. 19 It is preferred to use ΔS _IR as a measure of omnidirectional reflectivity in order to use (see 19 and 21). It should be understood that the (ΔS _IR ) shift at the IR side edge can be measured and / or made in the visible FWHM.

With reference to FIG. 21, all observed from 0 ° (S _UV (0 ^o )) compared to the IR-side edge for reflections from the same reflector observed from 45 ° (S _UV (45 ^o )). The IR-side edge shift or substitution (ΔS _IR ) with respect to the reflection from the directional reflector provides the degree of omnidirectional properties of the omnidirectional reflector. It should be understood that the (ΔS _UV ) shift at the UV side can be measured and / or done in the visible FWHM.

Naturally, zero shift, i.e. no shift at all (ΔS _i = 0 nm; i = IR, UV) characterizes a perfect omnidirectional reflector. However, the omnidirectional reflector disclosed herein appears to the human eye as if the surface color of the reflector does not change, so from a practical point of view the reflector is omnidirectional. , it is possible to provide a [Delta] S _L of less than 50nm. In some examples, the omnidirectional reflectors disclosed herein can provide ΔS _i less than 40 nm, in other examples can provide ΔS _i less than 30 nm, and in yet other examples. , A ΔS _i of less than 20 nm can be provided, and in yet another example, a ΔSL of less than 15 nm can be provided. Such a shift of ΔS _i can be measured by plotting the actual reflectance vs. wavelength of the reflector and / or, alternatively, by modeling the reflector if the material and layer thickness are known. ..

This shift of the omnidirectional reflector can be further measured by the low color shift. For example, the color shift of the pigment produced from the multilayer laminate based on the embodiment of the present invention is 30 ° or less as shown in FIG. 23 (see Δθ ₁ ), and in some examples, this color shift is 25. Less than or equal to °, preferably less than 20 °, even more preferably less than 15 °, even more preferably less than 10 °. In contrast, conventional pigments exhibit a color shift of 45 ° or greater (see Δθ ₂ ).

In summary, FIG. 24 shows a schematic of an omnidirectional multilayer thin film based on an embodiment of the present invention, in which the first layer 110 has a second layer 120 extending over it. A voluntary reflector layer 100 may be included. Further, a pair of symmetrical layers can sandwich the reflector layer 100, i.e., the reflector layer 100 has a first layer 110 disposed opposite to the layer 110 shown in the figure. This allows the reflector layer 100 to be sandwiched between a pair of first layers 110. In addition, the second layer 120 can be located on the opposite side of the reflector layer 100, which results in a five-layer structure. Therefore, it should be understood that the discussion of multilayer thin films presented herein also includes the possibility of mirror structures for one or more central layers. Therefore, FIG. 24 represents half of the five-layer multilayer laminate.

The first layer 110 and the second layer 120 may be a dielectric layer, that is, may be made of a dielectric material. Alternatively, one of the layers may be an absorber layer, such as a selective absorber layer or a non-selective absorber layer. For example, the first layer 110 may be a dielectric layer and the second layer 120 may be an absorber layer.

FIG. 25 represents half of the 7-layer design by reference number 20. The multi-layer laminate 20 has an additional layer 130 extending over the second layer 120. For example, this additional layer 130 may be a dielectric layer extending over the absorber layer 110. It should be understood that this layer 130 may be the same as or different from the material of layer 110. In addition, layer 130 can be added onto the multilayer laminate 20 by a method of laminating layers 100, 110 and / or 120, eg, by a method similar to or different from the sol-gel method.

FIG. 26 represents a nine-layer design by reference number 24, in which an additional layer 105 is placed between the optional reflector layer 100 and the first layer 110. For example, the additional layer 105 may be an absorber layer 105 extending between the reflector layer 100 and the dielectric layer 110. Table 2 below provides a list of materials that can form a variety of layers, although not completely exhaustive.

The method for producing the multilayer laminate disclosed in the present specification may be any method or process known to those skilled in the art, or a method not yet known to those skilled in the art. Commonly known methods include wet methods such as sol-gel method, layer-by-layer method, spin coating method and the like. Other known dry methods include chemical vapor deposition and physical vapor deposition, such as sputtering, electron beam deposition, and the like.

The multilayer laminate disclosed herein can be used with any coating material, such as pigments for paints, thin films applied to the surface, and the like.

As mentioned above, it provides an omnidirectional structural color pigment with a protective / environmental resistant coating. For example, reference to FIGS. 28 and 28 shows exemplary pigments that can be coated. In particular, FIG. 27 shows a three-layer pigment 12 with a central layer 100, a first non-oxide layer 112, a selective absorber layer 114, and an additional non-oxide layer 116 extending over the selective absorber layer. It is a schematic diagram. FIG. 28 is a schematic representation of the pigment 12a, which is similar to the pigment 12 except that there are additional layers 112a, 114a and an additional non-oxide layer 116a, as in FIG. 28A. It should be understood that layers 112-112a, 114-114, and / or 116-116a may or may not be made of the same material and may or may not have the same thickness.

FIG. 29 shows a schematic of the pigment 22, which shows the pigment 12a with the protective coating 200. In addition, FIG. 30 shows that the protective coating 200 may be obtained in a single layer or optionally in two or more layers, such as the first layer 202 and the second layer 204. The first layer 202 and / or the second layer 204 may be a layer of a single oxide or, optionally, a layer of mixed oxides made up of or containing two or more oxides. Please understand what you can do. For example, the protective coating 200 can be a single layer of oxide, such as a single layer of silicon oxide, aluminum oxide, zirconium oxide, or cerium oxide. Alternatively, the protective coating 200 can include a first layer 202 and a second layer 204, wherein the first layer 202 and the second layer 204 are silicon oxide, aluminum oxide, zirconium oxide, respectively. It can be a single layer of titanium oxide or cerium oxide. As another alternative, the first layer 202 may be a single layer of oxide, and the second foundation 204 is of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide or cerium oxide. It may be a layer of mixed oxides that is a combination of at least two. As yet another alternative, the second layer 204 may be a single oxide layer, and the first layer 204 may be at least one of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide or cerium oxide. It may be a layer of mixed oxides that is a combination of the two.

To better illustrate the invention, but without limiting its scope by any method, weather resistant omnidirectional structural color pigments and fabrication steps for producing such pigments are discussed below. ..

<Procedure 1> A 7-layer pigment that has been etched with phosphoric acid and coated with ₂ layers of SiO.

To a suspension containing 10 g of the 7-layer design pigment dispersed in 110 ml of acetone, 0.13 ml of phosphoric acid (85%) was added and stirred at room temperature for 30 minutes. The suspension was then filtered and washed twice with acetone. The solid particles were filtered to obtain a phosphoric acid-treated 7-layer pigment. This 7-layer pigment has a structure as shown in FIG. 28B, and is a central layer of Al, a pair of ZnS layers bonded to the Al layer, and a pair bonded to the pair of ZnS layers. Cr selective absorber layer and another ZnS layer bonded to this Cr absorber layer.

The phosphoric acid-treated 7-layer pigment was then suspended in 160 ml of ethanol in a round bottom flask equipped with a reflux condenser. To this suspension was added 35 g of water and 3.5 g of a 28% aqueous ammonia solution and heated to 65 ° C. Next, a solvent obtained by diluting 10 g of tetraethoxysilane with 13 ml of ethanol was added to the heated suspension with stirring little by little. The reaction mixture was stirred at 65 ° C. for 14 hours, after which the solid particles were filtered from the liquid, washed with ethanol and washed with isopropanol (IPA). The solid particles were dried at 100 ° C. for 24 hours to obtain a SiO _2- coated 7-layer pigment.

<Procedure 1A> 7-layer pigment coated with ₂ layers of SiO 160 ml of ethanol in a round-bottom flask equipped with a recirculation cooler without treating the 7-layer pigment in an amount of 10 g with phosphoric acid as in procedure 1. Suspended in. After adding 35 g of water and 3.5 g of a 28% aqueous ammonia solution to this suspension, the suspension was heated at 65 ° C. Next, a solvent obtained by diluting 10 g of tetraethoxysilane with 13 ml of ethanol was added to the heated suspension with stirring little by little. The reaction mixture was stirred at 65 ° C. for 14 hours, after which the solid particles were filtered from the liquid, washed with ethanol and washed with isopropanol (IPA). The solid particles were dried at 100 ° C. for 24 hours to obtain a SiO _2- coated 7-layer pigment.

<Procedure 2> A 7-layer pigment coated with SiO ₂ using an aqueous solution 15 g of a 7-layer pigment was placed in a 250 ml three-necked flask. Then, 100 ml of DI water was added, and this solution was stirred in an ethylene glycol bath heated to 80 ° C. A few drops of 1M NaOH solution was added to this solution to adjust the pH to 7.5. Next, 20 ml of Na ₂ SiO ₃ (13 wt% SiO ₂ ) was added to the solution at a constant flow rate of 0.1 ml / min using a syringe pump. When adding Na ₂ SiO ₃ , an automatic pH regulator was used to add a further 1M aqueous HCl solution to maintain the pH at 7.5. The mixture was cooled to room temperature, filtered, washed with IPA and dried at 100 ° C. for 24 hours. The coated material may be further annealed at 200 ° C. for 24 hours.

<Procedure 3> 7-layer pigment coated with Si ₂ O layer and mixed Si ₂ O-Al ₂ O ₃ layer 2 g of Pigment coated with SiO ₂ of Procedure 1 or 1-A is suspended in 20 ml of water to adjust the pH. It was set to 10 (adjusted with diluted NaOH solution). The suspension was heated at 60 ° C. with stirring in a 100 ml round bottom flask. Then, _18wt% Na 2 Si0 ₃ solution 0.5ml and 0.5MAl _{2 (SO 4) 3} solution 1 ml, within 1 hour at a constant flow rate to the pigment suspension was titrated simultaneously. The pH of this slurry was not adjusted. After the titration, the suspension was left for 30 minutes with stirring. The mixture was filtered and the residual solid particles were washed with DI water and then with IPA. The remaining solid particles were dried at 100 ° C. for 24 hours to obtain a 7-layer pigment having a SiO ₂ layer and an Al ₂ O ₃ layer.

<Procedure 4> 7-layer pigment having a coat of SiO ₂ layer and ZrO ₂ + Al ₂ O ₃ mixed layer 3 g of the pigment coated with SiO ₂ of procedure 1 or 1-A is suspended in 20 ml of ethanol in a 100 ml round bottom flask. , Stirred at room temperature. Further, 0.66 g of aluminum-tri-sec-butoxide and 2.47 ml of zirconium butoxide were dissolved in 15 ml of IPA. A mixture of aluminum-tri-sec-butoxide + zirconium butoxide was titrated into this pigment suspension at a constant flow rate within 2 hours. At the same time, an appropriate amount of 0.66 ml of DI water diluted in 2 ml of ethanol was administered. After titration, the suspension was stirred for an additional 30 minutes. The mixture was filtered and the residual solid particles were washed with DI water and then with IPA. The remaining solid particles were dried at 100 ° C. for 24 hours or, optionally, further annealed at 200 ° C. for 24 hours to obtain a 7-layer pigment having a SiO ₂ layer and a ZrO ₂ + Al ₂ O ₃ mixed layer. ..

<Procedure 5> 7-layer pigment having a coat of ₂ layers of SiO and a mixed layer of ZrO ₂ + Al ₂ O _{3 3} g of the pigment coated with SiO ₂ of procedure 1 or 1-A is applied to 20 ml of ethanol in a 100 ml round bottom flask. It became turbid and was stirred while heating at 50 ° C. Then, 0.5 ml of a 5 wt% NaAlO ₂ solution and 0.5 ml of a ZrOCl ₂ 10 wt% solution were simultaneously titrated into this pigment suspension at a constant flow rate within 30 minutes. The pH of the slurry was adjusted to 8 by adding diluted HCl or NaOH. After titration, the suspension was allowed to stand for 30 minutes with stirring. The mixture was filtered, washed with DI water and then washed with IPA. The remaining solid particles were dried at 100 ° C. for 24 hours or, optionally, further annealed at 200 ° C. for 24 hours.

<Step 6> SiO ₂ layer, a silicon oxide seven layer pigment Step 1 or 1-A with a coating of CeO ₂ layer, and _ZrO 2 + _Al 2 _{O 3} mixed layer pigment coated with (SiO _{2) (3.5g)} Was suspended in 26.83 ml of ethanol in a 100 ml round bottom flask, and stirred for 20 minutes while heating at 70 ° C. _Then, H 2 was titrated with a constant flow rate of 2 mL / hr and _{Ce (NO 3) 3 · 6H} 2 O0.33g in O1.18ml to the pigment suspension and further 1.5 h stirring the mixture after titration did. In this reaction, diluted NaOH was used to maintain the pH of this solution at 7.0. The residual solid particles of this mixture were filtered, washed 3 times with water and then 3 times with IPA. The remaining solid particles were dried at 100 ° C. for 24 hours to obtain a 7-layer pigment having ₂ layers of SiO and ₂ layers of CeO.

Next, 3 g of this coated pigment was diluted with 20 ml of ethanol in a 100 ml round bottom flask and stirred at room temperature. A mixture of 0.66 g of aluminum-tri-sec-butoxide and 2.47 ml of zirconium butoxide in 15 ml of IPA was added to the pigment suspension at a constant flow rate within 2 hours. At the same time, an appropriate amount of 0.66 ml of DI water diluted in 2 ml of ethanol was administered. After titration, the suspension was stirred for an additional 30 minutes. The mixture was filtered and the residual solid particles were washed with DI water and then with IPA. 7 layers with SiO ₂ layer, CeO ₂ layer and ZrO ₂ + Al ₂ O ₃ mixed layer by drying the remaining solid particles at 100 ° C. for 24 hours, or by alternative annealing at 200 ° C. for 24 hours. Obtained a pigment.

<Procedure 7> 7-layer pigment coated with CeO ₂ layer and ZrO ₂ + Al ₂ O ₃ mixed layer

3 g of the 7-layer design pigment was suspended in 20 ml of IPA in a 100 ml round bottom flask and stirred at 75 ° C. Ce solution dissolved in IPA20ml a _{(NO 3) 3 · 6H 2} O0.44g, 1 hour, was titrated with constant flow. At the same time, 0.15 ml of ethylenediamine (EDA) diluted in 0.9 ml of DI water was weighed. 0.15 ml of EDA diluted in 0.9 ml of additional DI water was weighed. After titration, the suspension was stirred for an additional 15 minutes. The mixture was filtered and the remaining solid particles were washed with IPA. The remaining solid particles were dried at 100 ° C. for 5 hours to obtain a 7-layer pigment having _two CeO layers.

Then, the pigment coated with CeO ₂ was diluted with 20 ml of ethanol in a 100 ml round bottom flask, and the mixture was stirred at room temperature. Next, a mixture of 0.66 g of aluminum-tri-sec-butoxide and 2.47 ml of zirconium butoxide diluted to 15 ml of IPA was titrated into the pigment suspension at a rate of 2 hours. At the same time, 0.66 ml of DI water diluted in 2 ml of ethanol was weighed. After titration, the suspension was stirred for an additional 30 minutes. The mixture was filtered and the remaining solid particles were washed with ethanol and then with IPA. The remaining solid particles were dried at 100 ° C. for 24 hours or, optionally, further annealed at 200 ° C. for 24 hours to obtain a 7-layer pigment having a CeO ₂ layer and a ZrO ₂ + Al ₂ O ₃ mixed layer.

<Procedure 8> 7-layer pigment having ₂ layers of ZrO ₂ g of a 7-layer design pigment was suspended in 30 ml of ethanol in a 100 ml round-bottom flask and stirred at room temperature. A solution of 2.75 ml of zirconium butoxide (80% in 1-butanol) in 10 ml of ethanol was titrated at an hour rate. At the same time, 1 ml of DI water diluted in 3 ml of ethanol was weighed. After titration, the suspension was stirred for an additional 15 minutes. Residual solid particles were filtered from the solution, washed with ethanol and dried at 100 ° C. for 5 hours, or optionally further annealed at 200 ° C. for 24 hours to give a 7-layer pigment with _two ZrO layers.
<Procedure 9> 7-layer pigment coated with ₂ layers of SiO and ₃ layers of Al ₂ O 2 g of the SiO _2- coated pigment of procedure 1 or 1A has a pH of about 8 in a 100 ml round-bottom flask (diluted NaOH solution). Suspended in 20 ml of water (prepared in), heated to 50 ° C. and continuously stirred. Then 0.5 ml of a 5 wt% NaAlO ₂ solution was titrated into this pigment suspension at a rate of 30 minutes. The pH of this slurry was adjusted to 8 with a 1M HCl solution. After titration, the suspension was allowed to stand for 30 minutes with stirring. The mixture was filtered, washed with DI water and then washed with IPA. Drying at 100 ° C. for 24 hours gave a coated pigment.

<Procedure 10> A 7-layer pigment 250 ml 3-port round-bottom flask coated with ₂ layers of SiO and ₂ layers of TiO was placed in an ethylene glycol oil bath, and the temperature was set to 80 ° C. Then, 15 g of the SiO ₂ coated small pieces of Procedure 1 or 1A and 100 ml of DI water were placed in a flask and stirred at 400 rpm. The pH of this solution was adjusted to 2 by adding a few drops of concentrated HCl solution. A pre-diluted 35% TiCl ₄ solution was then titrated into the mixture at 0.1 ml / min with a syringe pump. To keep the pH constant, a base solution, NaOH solution (8M), was titrated into the flask with a child pH regulator. During precipitation, small samples were removed at specific time intervals to measure layer thickness. The mixture was cooled to room temperature, then filtered, washed with IPA, dried at 100 ° C. for 24 hours, or optionally further annealed at 200 ° C. for 24 hours.

The weather resistance properties of the coated pigments were tested by the following methods. Seven columnar heat-resistant glass flasks (capacity 120 ml) were used as photoreaction vessels. Each flask contained 40 ml of a fluorescent red dye (eosin B) solution (1x10-5M) and tested 13.3 mg of pigment. The pigment-eosin B solution was electromagnetically stirred under dark conditions for 30 minutes and then exposed to light from a solar simulator (Oriol Sol2A class ABA solar simulator). For each pigment, a pigment of the same type wrapped in aluminum foil was used as a direct standard control. In addition, commercial TiO ₂ (Degussa P25) was used as a reference for comparing photocatalytic activity under similar experimental conditions. UV / Vis absorption spectra after exposure to light for 65 hours were recorded to detect the photocatalytic activity of each sample.

The results of the test were plotted as relative photocatalytic activity vs. pigment type as shown in FIG. In addition, a 7-layer pigment without a protective coating was set to exhibit 100% photocatalytic activity and was used as a comparison with a coated pigment sample. As shown in FIG. 31, all coated pigment samples exhibited reduced photocatalytic activity compared to uncoated samples. In addition, a 7-layer pigment with a SiO ₂ coating (labeled with P / S), a 7-layer pigment with a SiO ₂ coating layer and a ZrO ₂ + Al2O ₃ mixed coating layer (labeled with P / S / Z-A). ), A 7-layer pigment (labeled with P / S / C / ZA) having a SiO ₂ coating layer, a CeO ₂ coating layer and a ZrO ₂ + Al2O ₃ mixed coating layer, and a CeO ₂ coating layer and ZrO ₂ + Al2O ₃ Seven-layer pigments with mixed coating layers (labeled with P / C / Z-A) exhibited a reduction in photocatalytic activity of at least 50% compared to uncoated pigments. In contrast, 7-layer pigments with a SiO ₂ coating layer and 7-layer pigments with a SiO ₂ + Al ₂ O ₃ coating layer showed only a 33.8% reduction in photocatalytic activity.

Scanning electron microscope images of the 7-layer pigment before and after coating with the SiO ₂ layer and the ZrO _2- Al ₂ O ₃ layer (procedure 4) are shown in FIGS. 32A and 32B, respectively. As shown in the image, the surface of the pigment is smooth and the physical shape and structural preservation after coating are similar to those of the pigment before coating. In addition, the EDX dot map image of the 7-layer omnidirectional structural color pigment in which the ZnS layer on the outer surface is coated with the first SiO ₂ layer and the second ZrO _2- Al ₂ O ₃ (procedure 4) mixed layer protective coating. Indicates that Zn, S, Si, Zr, and Al are relatively highly concentrated in the coating structure.

As a summary of the coatings, the steps used to make the coatings, coating thickness, coating thickness uniformity, and photocatalytic activity are shown in Table 3 below.

From the above, Table 4 provides a range of various oxide layers, coatable substrates, and coating thicknesses in this teaching.

In addition to the above, the omnidirectional structural color pigment having a protective coating may be subjected to an organosilane surface treatment. For example, in one exemplary organosilane step treatment, 0.5 g of the pigment having one or more protective layers described above was placed in a 100 ml round bottom flask at a pH of approximately 5.0 (adjusted with a diluted acetic acid solution). Suspended in 10 ml of EtOH / water (4: 1). The slurry was sonicated for 20 seconds and stirred at 500 rpm for 15 minutes. The chemical was then added to the slurry with 0.1-0.5 vol% organosilane and the solution was stirred at 500 rpm for an additional 2 hours. The slurry was centrifuged or filtered using DI water and the residual pigment was redispersed in 10 ml of EtOH / water (4: 1) solution. The pigment-EtOH / water slurry was heated to 65 ° C. under reflux and stirred at 500 rpm for 30 minutes. The slurry was then centrifuged or filtered using DI water and then IPA to give a cake of pigment particles. Finally, the cake was dried at 100 ° C. for 12 hours.

In the organosilane step, any organosilane coupling agent known to those skilled in the art can be used, for example N- (2-aminoethyl) -3-aminopropyltrimethoxysilane (APTMS), N- [3- (Trimethoxysilyl) propyl] ethylenediamine 3-mesoalkyloxypropyltrimethoxy-silane (MAPTMS), N- [2 (vinylbenzylamino) -ethyl] -3-aminopropyltrimethoxysilane, 3-glycid-oxypropyltri Includes methoxysilane and the like.

The above examples and embodiments are for illustration purposes only, and modifications, modifications, and similarities apparent to those skilled in the art are within the scope of the invention. Therefore, the scope of the present invention is defined by the claims and all equivalents thereof.

The present invention further includes the following embodiments:
1. 1. A pigment having a first layer of a first material and a second layer of a second material, the second layer extending over the first layer and exposing the pigment to broadband electromagnetic radiation. And electromagnetic radiation where the pigment has a given half-width (FWMH) less than 300 nm and a given color shift less than 30 ° in the CIELAB color space when viewed from an angle between 0 ° and 45 °. A band-reflecting pigment and a weather-resistant coating covering the outer surface of the pigment, which reduces the photocatalytic activity of the pigment by at least 50% compared to the pigment without the weather-resistant coating. Omnidirectional structural color pigment with weather resistant coating.
2. The omnidirectional structural color pigment having a protective coating according to the above 2, wherein the weather resistant coating has an oxide layer.
3. 3. The omnidirectional structural color pigment having a protective coating according to the above 2, wherein the oxide layer is selected from the group consisting of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, and cerium oxide.
4. 3. The protective coating according to 3, wherein the weather correction coating has a first oxide layer and a second oxide layer, and the second oxide layer is different from the first oxide layer. Omnidirectional structural color pigment with.
5. The omnidirectional structural color pigment having a protective coating according to 4 above, wherein the second oxide layer is a mixed oxide layer which is a combination of two different oxides.
6. The first oxide layer is silicon oxide, and the second oxide layer is selected from at least two of the group consisting of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, and cerium oxide. The omnidirectional structural color pigment having a protective coating according to 5.
7. The omnidirectional structural color pigment having a protective coating according to 1 above, wherein the pigment does not contain an oxide layer.

Claims (16)

A pigment having a first layer of a first material and a second layer of a second material, the second layer extending over the first layer and exposing the pigment to broadband electromagnetic radiation. And when observed from an angle between 0 ° and 45 °, the pigment reflects a band of electromagnetic radiation with a given half-width (FWMH) less than 300 nm and a given color shift less than 30 °. A weather resistant coating that coats the pigment and the outer surface of the pigment and reduces the photocatalytic activity of the pigment by at least 50% as compared to the pigment without the weather resistant coating. An omnidirectional structural color pigment with a protective coating. The omnidirectional structural color pigment having a protective coating according to claim 1, wherein the weather resistant coating has an oxide layer. The omnidirectional structural color pigment having a protective coating according to claim 2, wherein the oxide layer is selected from the group consisting of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, and cerium oxide. The protection according to claim 3, wherein the weather correction coating has a first oxide layer and a second oxide layer, and the second oxide layer is different from the first oxide layer. Omnidirectional structural color pigment with coating. The omnidirectional structural color pigment having a protective coating according to claim 4, wherein the second oxide layer is a mixed oxide layer which is a combination of two different oxides. The first oxide layer is silicon oxide, and the second oxide layer is selected from at least two in the group consisting of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, and cerium oxide. The omnidirectional structural color pigment having a protective coating according to claim 5. The omnidirectional structural color pigment having a protective coating according to claim 1, wherein the pigment does not contain an oxide layer. Supplying a plurality of pigment particles, where each of the pigment particles has a first layer of a first material and a second layer of a second material, the second layer being said first. Extending over layers of, the pigment is exposed to wideband electromagnetic radiation and has a given half-width (FWMH) less than 300 nm when viewed from an angle between 0 ° and 45 °, and 30 °. To form a pigment suspension by suspending a plurality of the pigment particles reflecting a band of electromagnetic radiation having a smaller given color shift in a first liquid.
To supply a second liquid and an oxide precursor having an oxide constituent element selected from silicon, aluminum, zirconium, cerium and titanium.
Mixing a pigment suspension and an oxide precursor, where this mixing deposits a weather resistant oxide coating on top of the plurality of said pigment particles and is compared to a plurality of pigment particles having the weather resistant coating. A method for producing an omnidirectional structural color pigment having a protective coating, which comprises reducing the photocatalytic activity of the plurality of said pigment particles by at least 50%. The method according to claim 8, wherein the first liquid is a first organic solvent and the second liquid is a second organic solvent. The method according to claim 9, wherein the first organic solvent and the second organic solvent are organic polar solvents. The method according to claim 10, wherein the first organic solvent and the second organic solvent are selected from the group consisting of n-propyl alcohol, isopropyl alcohol, ethanol, n-butanol, and acetone. 11. The method of claim 11, wherein the first organic solvent and the second organic solvent are protonic organic polar solvents. The method according to claim 12, wherein the first organic solvent and the second organic solvent are the same protonic organic polar solvent. Silicon, which is an oxide constituent element, is in the form of tetraethoxysilane, and aluminum, which is an oxide constituent element, is in at least one form of aluminum sulfate and aluminum-tri-sec-butoxide, and is an oxide constituent element. Zyroxide is in the form of zirconium butoxide, cerium, which is an oxide constituent element, is in at least one form of cerium hexahydrate nitrate and cerium sulfate, and titanium, which is an oxide constituent element, is titanium ethoxydo. , Titanium isopropoxide, and the method of claim 13, which may be in at least one form of titanium-n-butoxide. The method of claim 8, wherein the first liquid is a first aqueous liquid and the second liquid is a second aqueous liquid. The oxide constituent element is in the form of sodium silicate, and the oxide constituent element aluminum is in at least one form of aluminum sulfate, aluminum sulfate hydrate, and sodium aluminate, and is an oxide constituent element. A certain zirconium is in the form of zirconium chloride octahydrate, the oxide constituent element cerium is in the form of cerium sulfate hexahydrate, and the oxide constituent element titanium is in the form of titanium tetrachloride. The method according to claim 15.