JP2016047917A - Non-color shifting multilayer structures and protective coatings on structures - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an omnidirectional structural color pigment having a protective coating.SOLUTION: An omnidirectional structural color pigment 10 of the invention has a first layer 110 of a first material and a second layer 120 of a second material, the second layer 120 extending across the first layer 110. In addition, the pigment 10 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 10 is exposed to broadband electromagnetic radiation and viewed from angles between 0° and 45°. The pigment 10 has a protective coating with a weather resistant coating that covers an outer surface of the pigment and reduces a relative photocatalytic activity of the pigment 10 by at least 50%.SELECTED DRAWING: Figure 24

Description

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

<Cross-reference of related applications>
This application is a continuation-in-part (CIP) of US patent application Ser. No. 14 / 242,429 filed Apr. 1, 2014, which further includes US patent application Ser. No. 14/14, filed Dec. 23, 2013. No. 138,499, which is further CIP of U.S. Patent Application No. 13 / 913,402, filed June 8, 2013, which is further U.S. Patent, filed Feb. 6, 2013. Application No. 13 / 760,699, which is further CIP of U.S. Patent Application No. 13 / 572,071, filed on August 10, 2012, which is further disclosed on February 5, 2012. CIP of U.S. Patent Application No. 13 / 021,730 filed, which is further U.S. Patent Application No. 112 / 793,772 filed June 4, 2010 (U.S. Patent No. 8,736,959). Is the CIP This is further the CIP of US patent application Ser. No. 12 / 388,395 filed Feb. 18, 2009 (US Pat. No. 8,749,881), which was further filed Aug. 12, 2007. US patent application Ser. No. 11 / 837,529 (US Pat. No. 7,903,339). U.S. Patent Application No. 13 / 913,402 filed June 8, 2013 is a CIP of U.S. Patent No. 13 / 014,398 filed Jan. 26, 2011, which is further referred to as Jun. 4, 2010. US Patent No. 12 / 793,772 of Japanese application. US Patent Application No. 13 / 014,398, filed January 26, 2011, is a CIP of US Patent No. 12 / 686,861 filed January 13, 2010, which is further February 19, 2009. The CIP of US patent application Ser. No. 12 / 389,256 (US Pat. No. 8,329,247), all of which are incorporated by reference in their entirety.

  Pigments made from multilayer laminates are known. In addition, pigments that exhibit or provide high chroma omnidirectional structural colors are also known. However, these prior art pigments required as many as 39 thin film layers to obtain the desired color characteristics.

  It should be understood that the cost associated with the production of thin film multilayer pigments is proportional to the number of layers required. Thus, the costs associated with producing a high saturation omnidirectional structural color using a multilayer stack of dielectric materials can be very expensive. Therefore, high saturation omnidirectional structural colors that require minimal thin film layers are desirable.

  In addition to the above, it should be understood that pigments may fade, discolor, etc. when exposed to sunlight, and particularly ultraviolet light. Therefore, there is a further demand for weather-resistant high chroma omnidirectional structural color pigments.

  An omnidirectional structural color pigment having a protective coating is provided. The pigment has a first layer of a first material and a second layer of a second material, the second layer extending over the first layer. In addition, when the pigment is exposed to broadband electromagnetic radiation and viewed 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 a band of electromagnetic radiation having a shift. 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 weatherable coating can include an oxide layer, and the oxide layer can be selected from silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, and / or cerium oxide. In addition, the weatherable coating can include a first oxide layer and a second oxide layer, wherein the second oxide layer is different from the first oxide layer. Further, the second oxide layer may be a mixed oxide layer that is a combination of at least two different oxides. Finally, the pigment itself, ie, except for the protective coating, does not have an oxide layer.

  Further disclosed is a method for producing an omnidirectional structural color pigment having a protective coating. The method includes providing a plurality of pigment particles having the structure and characteristics described above, and suspending the plurality of pigment particles in a first liquid to form a pigment suspension. In addition, an oxide precursor comprising a second liquid and an oxide constituent element such as silicon, aluminum, zirconium, titanium, or cerium is provided. Mixing the pigment suspension with the oxide precursor results in precipitation of a plurality of pigment particles with a weatherable oxide coating, which coating has a relative photocatalytic activity of the pigment of at least 50. % Decrease.

  In some examples, the first liquid is a first organic solvent and the second liquid is a second organic solvent. Furthermore, the first and second organic solvents may be organic polar solvents such as n-propyl alcohol, isopropyl alcohol, ethanol, n-butanol, and acetone. In other examples, the first organic solvent and the second organic solvent may be polar protic organic solvents.

  With respect to the oxide precursor, the oxide constituent silicon may be in the form of tetraethoxysilane, and the oxide constituent aluminum is at least aluminum sulfate and aluminum-tri-sec-butoxide. The oxide constituent zirconium may be in the form of zirconium butoxide, and the oxide constituent cerium is at least one of cerium nitrate hexahydrate and cerium sulfate. One form may be used, and the oxide constituent element titanium may be at least one form of titanium ethoxide, titanium isopropoxide, and titanium butoxide.

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

FIG. 1A is a schematic illustration of a dielectric layer (DL) reflecting or transmitting incident electromagnetic radiation. FIG. 1B is a schematic illustration of a reflector layer (RL) reflecting incident electromagnetic radiation. FIG. 1C is a schematic illustration of an absorber layer (AL) absorbing incident electromagnetic radiation. FIG. 1D is a schematic illustration of a selective absorber layer (SAL) that reflects, absorbs, and transmits incident electromagnetic radiation. FIG. 2 is a schematic representation of the reflection and transmission of incident electromagnetic radiation by a first generation omnidirectional structural color multilayer film made from a plurality of dielectric layers. FIG. 3 is a schematic diagram of a first generation omnidirectional structural color multilayer film made from a plurality of dielectric layers. FIG. 4 is a graph representing a comparison of 0.2% range to mid-range percentage 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 wavelength in cases 1, 2, and 3 shown in FIG. FIG. 7 is a schematic diagram of the reflection and absorption of incident electromagnetic radiation by a second generation omnidirectional structural color multilayer film made of a plurality of dielectric layers and one absorber layer. FIG. 8 is a schematic diagram of a second generation omnidirectional structural color multilayer film made of multiple dielectric layers, an absorber layer, and / or a reflector layer. FIG. 9A shows a second generation 5 made from a plurality of dielectric layers and absorber / reflector layers with a chroma (C *) of 100 and a reflectivity (maximum reflectivity) of 60%. 1 is a schematic diagram of a layer omnidirectional structural color multilayer film. FIG. 9B shows the second generation five-layer omnidirectional structural color multilayer shown in FIG. 9A compared to the first generation eleven-layer omnidirectional structural color multilayer film observed from an angle between 0 ° and 45 °. It is a graph of the reflectance of a thin film versus wavelength. FIG. 10 is a schematic diagram of a third generation omnidirectional structural color multilayer 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 ) versus 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. This is a graph. FIG. 12 is a schematic representation of a dielectric layer when it is exposed to electromagnetic radiation at an angle θ from the normal direction of the outer surface of the dielectric layer, extending over the substrate or reflector layer. FIG. 13 is a schematic diagram of a ZnS dielectric layer with a Cr absorber layer disposed at a zero or near zero electric field point in the ZnS dielectric layer for EMR having a wavelength of 434 nm. FIG. 14 shows the percentage of reflection versus reflection EMR when a multilayer stack without a Cr absorber layer (eg, FIG. 1A) and a multilayer stack with a Cr absorber layer (eg, FIG. 3A) are exposed to white light. It is a graph of a wavelength. FIG. 15A is a graph of first and second harmonics represented by a ZnS dielectric layer (eg, FIG. 4A) extending across the Al reflector layer. FIG. 15B shows that the ZnS dielectric layer extends over the Al reflector layer and the Cr absorber layer is placed in the ZnS dielectric layer so that this second harmonic shown in FIG. 8A is absorbed. FIG. 6 is a graph of percent reflection versus EMR wavelength for a multilayer stack. FIG. 15C shows that the ZnS dielectric layer extends over the Al reflector layer and that the Cr absorber layer is disposed in the ZnS dielectric layer so that this first harmonic shown in FIG. 8A is absorbed. FIG. 6 is a graph of percent reflection versus EMR wavelength for a multilayer stack. FIG. 16A is a graph of the square of the electric field versus the thickness of the dielectric layer showing the angular dependence of the electric field of the Cr absorber layer on the exposure of incident light from an angle between 0 ° and 45 °. FIG. 16B shows% Absorption vs. Reflected EMR wavelength by Cr absorber layer when exposed to white light from an angle between 0 ° and 45 ° to the normal to the outer surface (0 ° to the normal to the surface). It is a graph of. FIG. 17A is a schematic representation of a red omnidirectional structural color multilayer stack, in accordance with an embodiment of the present invention. FIG. 17B is a graph of reflected EMR wavelength for% light absorption of the Cu absorber layer shown in FIG. 10A versus white light exposure from an angle between 0 ° and 45 ° for the multilayer stack shown in FIG. 10A. is there. FIG. 18 shows the reflectance% versus the reflected EMR wavelength between the calculated / simulated data and the experimental data to prove the concept of the red omnidirectional structural color multilayer stack when white light is exposed from an angle of 0 °. It is the graph compared. FIG. 19 is a graph of reflectance% versus wavelength for an omnidirectional structural color multilayer stack according to an embodiment of the present invention. FIG. 20 is a graph of reflectance% versus wavelength for an omnidirectional structural color multilayer stack according to an embodiment of the present invention. FIG. 21 is a graph of reflectance% versus wavelength for an omnidirectional structural color multilayer stack according to an embodiment of the present invention. FIG. 22 is a graph of reflectance% versus wavelength for an omnidirectional structural color multilayer stack according to an embodiment of the present invention. FIG. 23 shows a * b using CIELAB color space, comparing saturation and hue shift between a conventional paint and a paint made from a pigment according to an embodiment of the present invention (sample (b)). * A graph showing a part of the color map. FIG. 24 is a schematic diagram of an omnidirectional structural color multilayer stack according to an embodiment of the present invention. FIG. 25 is a schematic diagram of an omnidirectional structural color multilayer stack according to an embodiment of the present invention. FIG. 26 is a schematic diagram of an omnidirectional structural color multilayer stack according to an embodiment of the present invention. FIG. 27 is a schematic diagram of a four-layer omnidirectional structural color pigment according to an embodiment of the present invention. FIG. 28 is a schematic diagram of a seven-layer omnidirectional structural color pigment according to an embodiment of the present invention. FIG. 29 is a schematic representation of an 11-layer omnidirectional structural color pigment with a protective coating, according to an embodiment of the present invention. FIG. 30 is a schematic illustration of a protective coating comprising two or more layers according to an embodiment of the present invention. FIG. 31 is a plot of normalized relative photocatalytic activity of omnidirectional structural color pigments having 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 having a silicon oxide and zirconium oxide-aluminum oxide protective coating.

  Provides an omnidirectional structural color. This omnidirectional structural color reflects a narrow band of electromagnetic radiation in the visible spectrum and has a small or indistinguishable color shift when viewed from an angle between 0 ° and 45 ° In the specification, it is also called a multilayer laminate. 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 stack having a first layer and a second layer extending across the first layer. In certain examples, the multilayer stack reflects a narrow band of electromagnetic radiation having a FWMH of less than 300 nm, more preferably less than 200 nm, and in some examples less than 150 nm. When the multilayer film is exposed to broadband electromagnetic radiation, such as white light, and viewed from an angle between 0 ° and 45 °, the multilayer film is less than 50 nm, more preferably less than 40 nm, and even more preferably 30 nm. It also has a smaller color shift. Furthermore, the multilayer stack may or may not have a separate reflection band of electromagnetic radiation in the UV and / or IR region.

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

The first and second layers can be made from a dielectric material, and alternatively, the first and / or second layer can be made from an absorber material. The absorber material may be a selective absorber material such as Cu, Au, Zn, Sn, alloys thereof, and the like, or alternatively, a colored dielectric material such as Fe ₂ O ₃ , Cu ₂ O, these And combinations of the same. This absorber material may further comprise a non-selective absorption material such as Cr, Ta, W, Mo, Ti, Ti nitride, Nb, Co, Si, Ge, Ni, Pd, V, ferric oxide, combinations thereof or Alloys as well as the same may be used. 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 stack further includes a first layer and a reflector layer over which the second layer extends, the reflector layer comprising, for example, Al, Ag, Pt, Cr, Cu, Zn, Au , Sn, these alloys and the like. This reflector layer usually has a thickness of between 30 and 200 nm.

  The multilayer stack may have a reflected narrow band of electromagnetic radiation having a symmetrical peak shape in the visible spectrum. Alternatively, the reflected narrow band of electromagnetic radiation in the visible spectrum can be adjacent to the UV region, so that part of the reflected band of electromagnetic radiation, ie the UV part, is not visible to the human eye. . Alternatively, the reflection band of electromagnetic radiation can have a portion thereof in the IR region, so that the IR portion is likewise invisible to the human eye.

  Regardless of whether the reflection band of this electromagnetic radiation in the visible spectrum is adjacent to the UV region, the IR region, or has a symmetric peak in the visible spectrum, the multilayer thin film disclosed herein is: It has a narrow band of reflection of electromagnetic radiation in the visible spectrum with low, small or unrecognizable color shift. This low or unrecognizable color shift may be in the form of a small shift in the central wavelength of the reflected narrow band of electromagnetic radiation. Alternatively, the low or unrecognizable color shift may be in the form of a small shift of the UV side edge or IR side edge of the reflection band of electromagnetic radiation adjacent to the IR region or UV region, respectively. When observing multilayer thin films from angles between 0 ° and 45 °, such small shifts in the center wavelength, UV side edge, and / or IR side edge are usually less than 50 nm, in some examples Is less than 40 nm, and in other examples is 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, illustratively a silicon oxide layer, an aluminum oxide layer, a zirconium oxide layer, a titanium oxide layer, a cerium oxide layer, combinations thereof, and the like Can contain things. In some examples, the protective coating includes a first oxide layer and a second oxide layer. Furthermore, the first oxide layer and / or the second oxide layer may be a mixed oxide layer, that is, an oxide layer that is a combination of two types of oxides. Furthermore, as described above, the pigment itself may be in the form of a multilayer thin film that does not include an oxide layer.

  The method of producing the omnidirectional structural color pigment may or may not involve 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 omnidirectional structural color pigments and methods of making the pigments are provided later in this 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. Furthermore, the dielectric layer (DL) reflects a portion of incident electromagnetic radiation and transmits the other portion. In addition, incident electromagnetic radiation is equal to the transmitted and reflected portions, which are typically much larger than the reflected portions. The dielectric layer is made of a dielectric material, for example _{SiO 2,} TiO 2, ZnS, from 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 has essentially zero transmission. The reflector layer is typically made from 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 of, for example, graphite. Further, 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, partially transmitted and partially reflected. Thus, 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 materials such as thin layers of chromium, copper, brass, and bronze layers, and the like.

  For the present invention, the design and manufacture of three generations of thin layers of omnidirectional structural color is disclosed.

<First generation>
Referring 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 noted above, the normal transmission of incident electromagnetic radiation is much greater than the reflections on it, and thus many layers are required.

FIG. 3 shows a portion of a multilayer thin film made from 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 the layers merely indicate the boundaries between the different layers.

  Without being limited by principle, one design and manufacturing method or means for obtaining the desired multilayer stack is as follows.

When electromagnetic radiation strikes the surface of the material, this wave of radiation is reflected or transmitted from the material. Further, when electromagnetic radiation collides with the first end 12 of the multilayer laminate 10 at an angle θ ₀ , the reflection angles of the electromagnetic wave with respect to the surfaces of the high refractive index layer and the low layer 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 omni-directional reflectivity, the maximum refraction angle (θ _{H, Max} ) in the first layer is the first layer and second as a necessary but insufficient condition for the TE and TM modes of electromagnetic radiation. It is necessary to be smaller than the Brewster angle (θ _B ) of the interface between the layers. If this condition is not met, the TM mode of electromagnetic radiation does not reflect at the second and subsequent interfaces and therefore penetrates the structure.
Using this consideration,
as well as
Therefore, it is necessary to:

In addition to the requirements expressed by Equation 4, the electromagnetic wave of wavelength λ is directed to the multilayer structure at an angle θ 0, and the individual bilayers of the multilayer structure have thicknesses d _H and refractive indices n _H and n _L , respectively. If having a d _L, characteristic conversion matrix _{(F T)} can be expressed as follows.
This can also be expressed as:
here:
as well as
It is.
further,
here,
as well as
It is.
Clearly solving ρ _T for TE and TM:
as well as

  A band structure depending on the observation angle can be obtained from the boundary conditions for the edge, also known as the band edge, of the total reflection region. For the purposes of the present invention, the band edge is defined as a line equation that separates the total reflection and transmission areas for a given band structure.

The boundary condition for determining the band frequency of the high reflection band is given by the following condition.
Thus, from Equation 3:
Or another expression:
Combining Equations 15 and 7 yields the following band edge equation:
here:
as well as:
The symbol “+” in the above band edge formula represents the band edge in the case of the _long wavelength (λ _long ), and the symbol “−” represents the band edge in the case of the short wavelength (λ _short ).
Reorganizing equations 20 and 21:
About TE mode:
as well as,
About TM mode:
It is.

The approximate solution at the band edge can be determined by the following expression:
This approximate solution is reasonable considering the quarter wavelength design (described in more detail below) and the optical thicknesses of the alternating layers selected to be equal to each other. Furthermore, the cosine approaches 1 when the alternating layer optical thickness is relatively small. Thus, equations 23 and 24 yield approximate band edge equations:
About TE mode:
And about TM mode:

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

The central wavelength (λc) of the omnidirectional reflector is:
It can be determined by the relational expression
The center wavelength can be an important parameter, since its value suggests a long electromagnetic wave and / or an approximate range of the color spectrum to be reflected. Another important parameter that can provide suggestions regarding the width of the reflection band is defined as the range of wavelengths within the omni-directional reflection band to the mid-range ratio of wavelengths within the omni-directional reflection band. This “range to mid-range ratio” (η) is mathematically expressed as:
About TE mode
About TM mode:
Range to mid-range ratio can be expressed as a percentage, and for the purposes of the present invention, it is to be understood that the terms “range to mid-range ratio” and “range to mid-range ratio percentage” are used interchangeably. Further, it should be understood that the “range to mid range ratio” value presented with the “%” symbol is a percentage value of the “range to mid range ratio”. The “range to mid-range ratio” values for TM and TE modes can be calculated numerically from Equations 28 and 29 and can be plotted as a function of high and low refractive indices.

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

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

From the above, the multilayer stack 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 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 a 0.2% range-to-mid-range ratio for the TM and TE modes of electromagnetic radiation, plotted as a function of high refractive index versus 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 This relates to the case where the difference between the TM mode and the TE mode is very small. Further, FIG. 5 represents the reflectance percent of reflected electromagnetic radiation versus wavelength for a similar case of 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, in conjunction with the reference to FIG. 6, when the multilayer film is viewed from an angle between 0 ° and 45 °, Case 2 results in a color shift less than the center wavelength of 50 nm (Case II), and the multilayer When the film is observed from an angle between 0 ° and 45 °, Case III results in a color shift that is less than the central wavelength of 25 nm (Case III).

<2nd generation>
Referring to FIG. 7, an exemplary structure / design based on the second generation is shown. The multi-layer stack shown in FIG. 7 has a plurality of dielectric layers and an underlying absorber layer. In addition, no incident electromagnetic radiation is transmitted through this structure, ie 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 that a multilayer stack extends over a central absorber layer made of Cr, a first dielectric material layer (DL ₁ ) extending over the Cr absorber layer, DL ₁ layer. This provides a schematic representation of such a structure having a second dielectric material layer (DL ₂ ) and a DL ₁ layer extending over the DL ₂ layer. 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 a structure in which the central Cr layer is bonded to _two TiO ₂ layers, which are further bonded by two SiO ₂ layers. As shown by the plot, the layer thicknesses of TiO ₂ and SiO ₂ are not equal to each other. In addition, FIG. 9B shows the reflectance versus wavelength spectrum comparing the five-layer structure shown in FIG. 9A and the 13-layer structure based on the first generation design. As shown in FIG. 9B, viewing this structure from an angle between 0 ° and 45 ° results in a shift of the central wavelength that is less than 50 nm, preferably less than 25 nm. The fact that a five-layer structure based on the second generation behaves essentially the same as a 13-layer structure of the first generation is further illustrated 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 the DL ₁ layer. A third generation design is shown. In addition, another DL1 layer may or may not be provided and may or may not extend across 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 the different schemes utilized to design and manufacture the desired multilayer stack. In particular, zero or near zero field point thickness of the dielectric layer is utilized and discussed below.

  For example, FIG. 11A is a schematic illustration of a ZnS dielectric layer extending over an Al reflector layer. This ZnS dielectric layer has a total thickness of 143 nm and a zero or nearly zero electric field point at 77 nm for incident electromagnetic radiation having a wavelength of 500 nm. In other words, the ZnS dielectric layer has a zero or nearly zero electric field point at a distance of 77 nm from the Al reflector layer for incident EMR having a wavelength of 500 nm. In addition, FIG. 11B provides a graph of the electric field across the ZnS dielectric layer for different EMR wavelengths. As shown in the graph, the dielectric layer has zero or nearly zero electric field points at a thickness of 77 nm for incident EMR having a wavelength of 500 nm, but for incident EMR having wavelengths of 400 nm, 600 nm, and 700 nm. , Zero or nearly zero electric field point.

When referring to the calculation of the zero or near-zero field point, 12 on the base or central layer 2 having a reflectance n _s, the total thickness "D," the thickness of the increment "d", and reflectivity "n" The dielectric layer 4 having Incident light strikes the outer surface 5 of the dielectric layer 4 at an angle θ with respect to a line 6 perpendicular to the outer surface 5 and reflects from the outer surface 5 at the same angle. 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 strikes the surface 3 of the substrate layer at an angle θ _s .

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

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

Thus, in a simple state where θ _F = 0 or normal incidence, φ = k · n · d, and α = 0:
This can solve "d", i.e. where the electric field in the dielectric layer is zero.

  Referring to FIG. 13, the zero or nearly 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 this. In addition, a 15 nm thick Cr absorber layer is inserted from the Al reflector layer to a thickness of 70 nm, resulting in a zero or near zero electric field ZnS-Cr boundary. Thus, the inventive structure absorbs light having a wavelength of 434 nm through the Cr-ZnS boundary, but 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, so that 434 nm light passes through this boundary. However, since the Cr—ZnS boundary does not have a zero or nearly 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 the Al reflector. Not reflected by the layer.

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

  The result due to the presence of the Cr absorber layer in the multilayer stack of FIG. 13 is shown in FIG. As shown by this dotted line, corresponding to the ZnS dielectric layer shown in FIG. 13 without the Cr absorber layer, 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 500 nm wavelength region. Thus, there are two peaks that prevent the multilayer stack from providing a structural color.

  In contrast, the solid line in FIG. 14 corresponds to the structure shown in FIG. 13 where 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 reflectivity for wavelengths greater than 434 nm is provided by the Cr absorber layer. It should be understood that the sharp peak indicated by the solid line appears as a visually sharp / structural color. Furthermore, FIG. 14 shows where the reflected peak or band width is measured, ie the band width is also known as the half-width (FWHM), a reflectivity of 50% of the maximum reflection wavelength. Measured in part.

  Referring to the omnidirectional action of the multilayer stack shown in FIG. 13, this thickness of the ZnS dielectric layer can be designed or determined, which results in only the first harmonic of the reflected light. It should be understood that this is sufficient for a “blue” color, but further consideration is necessary to produce a “red” color. For example, for red, non-angle-dependent adjustment is difficult because it requires a thicker dielectric layer, which results in a high harmonic design, i.e. the second and third harmonics that should be. Waves are inevitable. Furthermore, the dark brown color space is very narrow. Thus, the red multilayer stack has a high angular change.

In order to overcome this high angular change in red, this application discloses a design / structure that provides a unique and novel, angle-independent red. For example, FIG. 15A shows a dielectric layer that exhibits first and second harmonics for incident white light when the outer surface of the dielectric layer is 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 multilayer stacks are blue (first harmonic) and red (second For example, it is not suitable for the desired “red only” color. Hence, this theory / structure has been developed that utilizes absorber layers to absorb undesired groups of harmonics. FIG. 15A shows the position of the central wavelength (λ _c ) of the reflection band for a given reflection peak and the dispersion or shift (Δλ _c) of this central wavelength when the sample is viewed from an angle between 0 ° and 45 °. ).

Referring to FIG. 15B, the second harmonic shown in FIG. 15A is absorbed by the Cr absorber layer at a suitable dielectric layer thickness (eg, 72 nm) and results in a sharp blue color. More importantly in the present invention, FIG. 15C provides a red color by absorbing the first harmonic by the Cr absorber layer at different dielectric layer thicknesses (eg, 125 nm). However, FIG. 15C further illustrates that the use of a Cr absorber layer is higher than the desired angular dependence of this multilayer stack, ie, greater than the desired Δλ _c .

  The relatively large shift for red compared to blue is that this dark red color space is very narrow and that the Cr absorber layer absorbs a color corresponding to a non-zero or nearly non-zero electric field, i.e. this It should be understood that due to the fact that it does not absorb light when the electric field is zero or nearly zero. Thus, FIG. 16A shows that this zero or near-zero electric field point for the light wavelength is different for different angles of incidence. Such a factor leads to the angle-independent absorptivity shown in FIG. Therefore, in order to further improve the design of the multilayer stack 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 stack in which a Cu absorber layer extends over a ZnS layer instead of a Cr absorber layer. The result of using such a “colored” or “selective” absorber layer is shown in FIG. 17B, which is more from the 0 ° and 45 ° absorption lines of the multilayer stack shown in FIG. 17A. It represents a “serious” grouping. Therefore, a comparison between FIG. 16B and FIG. 16B shows that there is a significant improvement in the angle independence of the absorption rate by using a selective absorber layer instead of a non-selective absorber layer. ing.

  Based on the above, a multilayer laminate structure for proof of concept was designed and fabricated. In addition, the calculation / simulation results for the samples to prove the concept and the actual experimental data were compared. In particular, and as shown in the graph plot of FIG. 18, a bright red color is produced (wavelengths greater than 700 nm are usually not visible to the human eye), and calculations / simulations and experiments obtained from actual samples A very good agreement was obtained with the light data. In other words, the calculation / simulation can be used to simulate or simulate the results of one or more embodiments of the present invention and / or the multilayer stack design of known multilayer stacks.

  An inventory of simulated and / or actually produced multilayer stack samples is provided in Table 1 below. As shown in the table, the inventive design disclosed herein includes at least five different layer structures. In addition, this sample was simulated and / or made from a wide area of material. The result was a sample exhibiting high saturation, low color shift, and perfect reflectivity. Further, 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.

  Referring to FIG. 19, a plot of percent reflectance versus reflected EMR wavelength is shown for an omnidirectional reflector when exposed to white light from angles of 0 ° and 45 ° relative to the surface of the reflector. As shown in the plot, the 0 ° and 45 ° curves represent the very low reflectivity provided by the omni-directional reflector for wavelengths greater than 500 nm, eg less than 20%. However, this reflector provides a sharp increase in reflectivity at wavelengths between 400 and 500 nm, as shown by the curve, and reaches a maximum of about 90% at 450 nm. It should be understood that the portion or area of the graph on the left hand side (UV side) of this curve represents the UV portion of the reflection band provided by this reflector.

This sharp increase in reflectivity provided by this omnidirectional reflector is characterized by the IR side edge of each curve extending from a low reflectivity portion at a wavelength greater than 500 nm to a high reflectivity portion, eg,> 70%. It is done. The straight line portion 200 on the IR end side is inclined at an angle (β) larger than 60 ° with respect to the x-axis, and has a length L of about 50 on the reflectance axis and an inclination of 1.2. In one example, the straight portion is inclined 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 of less than 200 nm, in some examples a visible FWMH of less than 150 nm and in other examples a visible FWMH of less than 100 nm. In addition, the center wavelength λ _c of the visible reflection band as shown in FIG. 19 is defined as a wavelength that is equidistant from the IR side end of the reflection band and the UV end of the UV spectrum of the visible FWHM.

  The term “visible FWHM” is the width of the reflection band between the IR end of this curve and the end of the UV spectral region beyond which the reflection provided by the omnidirectional reflector is not visible to the human eye. Should be understood as referring to. Thus, the inventive designs and multi-layer laminates disclosed herein use the invisible UV portion of electromagnetic radiation to provide a sharp 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 reflector disclosed herein provides a narrow band of reflected visible light. In order to do so, the invisible UV portion of the electromagnetic radiation spectrum is utilized.

Referring to FIG. 20, there is shown a generally contrasting reflection band that results when a multilayer stack according to an embodiment of the present invention is observed from 0 ° and 45 °. As shown in the figure, the reflection band produced when a multilayer stack according to an embodiment of the present invention is observed from 0 ° is less than 50 nm when the multilayer stack is observed from 45 ° (λ _c (45 ^o )). It has a color shift of the center wavelength (λ _c (0 ^o )), ie Δλ _c (0-45 ^o ) <50 nm. In addition, the FWMH of this 0 degree reflection band and 45 ° reflection band is less than 200 nm.

  FIG. 21 shows a plot of percent reflectance versus reflected EMR wavelength for another omnidirectional reflector design when exposed to white light from 0 ° and 45 ° angles to the surface of the reflector. Yes. As in FIG. 19 and as shown in the plot, the 0 ° and 45 ° curves show the very low reflectivity that this omni-directional reflector provides for wavelengths less than 550 nm, eg less than 10%. Show. However, this reflector provides a sharp increase in reflectivity at wavelengths between 560 and 570 nm, as shown by the curve, and reaches a maximum of about 90% at 700 nm. It should be understood that the portion or area of the graph on the right hand side (IR side) of this curve represents the IR portion of the reflection band provided by this reflector.

This sharp increase in reflectivity provided by this omnidirectional reflector is characterized by the UV side edge of each curve extending from a low reflectivity portion at a wavelength less than 550 nm to a high reflectivity portion, eg,> 70%. It is done. The straight line portion 200 on the UV end side is inclined at an angle (β) larger than 60 ° with respect to the x-axis, and has a length L of about 40 on the reflectance axis and an inclination of 1.4. In one example, the straight portion is inclined 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 of less than 200 nm, in some examples a visible FWMH of less than 150 nm and in other examples a visible FWMH of less than 100 nm. Furthermore, the center wavelength λ _c of this visible reflection band shown in FIG. 18 is defined as a wavelength that is 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” is the width of the reflection band between the UV end of this curve and the end of the IR spectral region beyond which the reflection supplied by the omnidirectional reflector is not visible to the human eye. Should be understood as referring to. Thus, the inventive designs and multi-layer laminates disclosed herein use the invisible IR portion of electromagnetic radiation to provide a sharp structural color. In other words, despite the fact that the reflector reflects a wider band of electromagnetic radiation that extends into the IR region, the omnidirectional reflector disclosed herein provides a narrow band of reflected visible light. In order to do so, the invisible IR portion of the electromagnetic radiation spectrum is utilized.

Referring to FIG. 22, the percent reflectance versus wavelength for an omnidirectional reflector of another seven layer design when exposed to white light from 0 ° and 45 ° angles to the surface of the reflector is shown. ing. In addition, it provides a definition or evaluation of the omnidirectional characteristics provided by the omnidirectional reflector disclosed herein. In particular, and when the reflection band produced by the reflector of the present invention is maximum, i.e., has a peak as shown in the figure, each curve exhibits a maximum reflectance or a center wavelength (λ _c ) defined as the wavelength experienced. Have The term maximum reflection wavelength is also used as λ _c .

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

For example, there is a shift or substitution of λ _c when the outer surface is viewed from an angle that appears to be inclined at 45 ° relative to the eyes of the viewer viewing this surface. This shift in λ _c (Δλc) provides a measure of the omnidirectional characteristics of the omnidirectional reflector. Of course, when there is zero shift, i.e. no shift, a complete omnidirectional reflector is obtained. However, the omnidirectional reflector disclosed herein appears to the human eye as if the surface color of the reflector has not changed, so that the reflector is omnidirectional from a practical standpoint, A Δλ _c of less than 50 nm can be provided. In some examples, the omnidirectional reflector disclosed herein can provide a Δλ _c of less than 40 nm, in other examples a Δλ _c of less than 30 nm, and in yet other examples a Δλ _c of less than 20 nm. _c , and in yet other examples, can provide a Δλ _c of less than 15 nm. Such a shift in Δλ _c is measured by plotting the actual reflectivity versus wavelength of the reflector, and / or by modeling the reflector if the material and layer thickness are known. be able to.

Another definition or characterization of the omnidirectional characteristics of the reflector can be measured by shifting the sides of a given series of angular reflection bands. For example, also with reference to FIG. 19, observed from 0 ° (S _IR (0 ^o )), compared to the IR-side edge for reflection from the same reflector observed from 45 ° (S _IR (45 ^o )). The IR-side edge shift or substitution (ΔS _IR ) for reflection from the omni-directional reflector provides a measure of the omni-directional characteristics of the omni-directional 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 to use the 19 and reference 21), it is preferable to use a [Delta] S _IR as a measure omnidirectional reflectivity. It should be understood that the (ΔS _IR ) shift of the IR side edge can be measured and / or done in the visible FWHM.

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

Of course, the zero shift, ie 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 color of the reflector's surface does not change, so from a practical standpoint, the reflector is omnidirectional. , ΔS _L of less than 50 nm can be provided. In some examples, the omnidirectional reflectors disclosed herein can provide ΔS _i of less than 40 nm, in other examples, can provide ΔS _i of less than 30 nm, and in other examples , ΔS _i of less than 20 nm can be provided, and in yet other examples, ΔSL of less than 15 nm can be provided. Such a shift in ΔS _i can be measured by plotting the actual reflectivity versus 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 a low color shift. For example, the color shift of a pigment made from a multilayer laminate according to an embodiment of the present invention is 30 ° or less (see Δθ ₁ ) as shown in FIG. 23, and in some examples this color shift is 25 Or less, preferably less than 20 °, more preferably less than 15 °, and even more preferably less than 10 °. In contrast, conventional pigments exhibit a color shift of 45 ° or greater (see Δθ ₂ ).

  In summary, a schematic representation of an omnidirectional multilayer thin film according to an embodiment of the present invention, with the first layer 110 having a second layer 120 extending therethrough, is shown in FIG. An optional reflector layer 100 may be included. Furthermore, a pair of symmetrical layers can sandwich the reflector layer 100, i.e. the reflector layer 100 has a first layer 110 disposed on the opposite side of the layer 110 shown in the figure. Thereby, the reflector layer 100 is sandwiched between the pair of first layers 110. In addition, the second layer 120 can be disposed on the opposite side of the reflector layer 100, resulting in a five-layer structure. Therefore, it should be understood that the discussion of multilayer thin films provided herein also includes the possibility of mirror structures with respect to one or more central layers. Accordingly, FIG. 24 represents half of a five layer multilayer stack.

  The first layer 110 and the second layer 120 may be dielectric layers, i.e. 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.

  In FIG. 25, reference numeral 20 represents half of the seven-layer design. The multilayer stack 20 has an additional layer 130 that extends across the second layer 120. For example, this additional layer 130 may be a dielectric layer that extends across 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, the layer 130 can be added on the multilayer stack 20 by a method of laminating the layers 100, 110 and / or 120, for example, a method similar to or different from the sol-gel method.

  FIG. 26 represents a nine-layer design by reference numeral 24, which has an additional layer 105 disposed between the optional reflector layer 100 and the first layer 110. For example, this additional layer 105 may be an absorber layer 105 that extends between the reflector layer 100 and the dielectric layer 110. A list of materials that can be used to make various layers, although not completely covered, is shown in Table 2 below.

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

  The multilayer laminate disclosed herein can be used for any coating material, such as paint pigments, thin films on surfaces, and the like.

  As described above, omnidirectional structural color pigments with protective / environmental resistant coatings are provided. For example, referring to FIGS. 28 and 28, exemplary pigments that can be coated are shown. 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 across the selective absorber layer. It is a schematic diagram. FIG. 28 is a schematic diagram of pigment 12a, which is similar to 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 type of material and may or may not have the same thickness.

  FIG. 29 shows a schematic diagram of the pigment 22, which shows the pigment 12 a having a protective coating 200. In addition, FIG. 30 illustrates that the protective coating 200 may be a single layer or alternatively 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 single oxide layer, or alternatively a mixed oxide layer made of or containing two or more oxides. Please understand that you can. For example, the protective coating 200 can be a single oxide layer, 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, and the first layer 202 and the second layer 204 are silicon oxide, aluminum oxide, zirconium oxide, It can be a single layer of titanium oxide or cerium oxide. As another alternative, the first layer 202 may be a single oxide layer and the second foundation 204 is made of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide or cerium oxide. It may be a layer of mixed oxide 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 is at least one of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, or cerium oxide. It may be a mixed oxide layer that is a combination of the two.

  To better illustrate the present invention, but not to limit its scope in any way, the weather resistant omnidirectional structural color pigments and the fabrication process for making such pigments are discussed below. .

<Procedure 1> Seven-layer pigment etched with phosphoric acid and coated with SiO ₂ layer

  To a suspension containing 10 g of 7-layer designed pigment dispersed in 110 ml of acetone, 0.13 ml of phosphoric acid (85%) was added and stirred at room temperature for 30 minutes. This suspension was then filtered and washed twice with acetone. By filtering the solid particles, a seven-layer pigment treated with phosphoric acid was obtained. The seven-layer pigment has a structure as shown in FIG. 28B, and includes 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. A Cr selective absorber layer and another ZnS layer bonded to the Cr absorber layer.

This phosphated seven-layer pigment was then suspended in 160 ml of ethanol in a round bottom flask equipped with a reflux condenser. 35 g of water and 3.5 g of 28% aqueous ammonia solution were added to this suspension and heated to 65 ° C. Next, a solvent prepared by diluting 10 g of tetraethoxysilane with 13 ml of ethanol was added to the heated suspension while 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.

A seven-layer pigment of the amount of <Step 1A> 7-layer pigment 10g coated with SiO ₂ layer, without treatment with phosphoric acid, such as steps 1, 160 ml of ethanol in a round bottom flask equipped with a reflux condenser It was suspended in. To this suspension, 35 g of water and 3.5 g of 28% aqueous ammonia solution were added, and then heated at 65 ° C. Next, a solvent prepared by diluting 10 g of tetraethoxysilane with 13 ml of ethanol was added to the heated suspension while 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> Seven-layer pigment coated with SiO ₂ using an aqueous solution 15 g of seven-layer pigment was placed in a 250 ml three-necked flask. 100 ml of DI water was then added and the solution was stirred in an ethylene glycol bath heated to 80 ° C. To this solution was added a few drops of 1M NaOH 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 adjuster was used to further add 1M aqueous HCl 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. This coated material may be further annealed at 200 ° C. for 24 hours.

<Procedure 3> Seven-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, and the pH is about 10 (adjusted with dilute NaOH solution). This suspension was heated at 60 ° C. with stirring in a 100 ml round bottom flask. Then, 0.5 ml of 18 wt% Na ₂ SiO ₃ solution and 1 ml of 0.5 MAl ₂ (SO ₄ ) ₃ solution were titrated simultaneously to the pigment suspension at a constant flow rate within 1 hour. The pH of this slurry was not adjusted. After titration, the suspension was left for 30 minutes with stirring. The mixture was filtered and the remaining solid particles were washed with DI water followed by IPA. The remaining solid particles were dried at 100 ° C. for 24 hours to obtain a seven-layer pigment having a SiO ₂ layer and an Al ₂ O ₃ layer.

<Step 4> SiO2 layer and _ZrO 2 + _Al 2 _{O 3} pigment 3g coated with SiO ₂ of the seven-layer pigment Step 1 or 1-A with a coating of the mixed layer is suspended in ethanol 20ml round bottom flask 100ml And 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. The aluminum-tri-sec-butoxide + zirconium butoxide mixture was titrated to 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 the titration, the suspension was stirred for another 30 minutes. The mixture was filtered and the remaining solid particles were washed with DI water followed by IPA. Residual solid particles were dried at 100 ° C. for 24 hours, or alternatively 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> Seven-layer pigment having coat of SiO ₂ layer and ZrO ₂ + Al ₂ O ₃ mixed layer Procedure 1 or 3 g of pigment coated with 1-A SiO ₂ was suspended in 20 ml of ethanol in a 100 ml round bottom flask. It became cloudy and stirred while heating to 50 ° C. Thereafter, 0.5 ml of 5 wt% NaAlO ₂ solution and 0.5 ml of ZrOCl ₂ 10 wt% solution were titrated simultaneously into the 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 left for 30 minutes with stirring. The mixture was filtered and washed with DI water followed by IPA. The remaining solid particles were dried at 100 ° C. for 24 hours, or alternatively further annealed at 200 ° C. for 24 hours.

<Procedure 6> Seven-layer pigment having a coating of SiO ₂ layer, CeO ₂ layer and ZrO ₂ + Al ₂ O ₃ mixed layer Procedure 1 or pigment coated with 1-A silicon oxide (SiO ₂₎ (3.5 g) Was suspended in 26.83 ml of ethanol in a 100 ml round bottom flask and stirred for 20 minutes while heating to 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 the solution at 7.0. The remaining solid particles of this mixture were filtered, washed 3 times with water and then washed 3 times with IPA. The remaining solid particles were dried at 100 ° C. for 24 hours to obtain a seven-layer pigment having a SiO ₂ layer and a CeO ₂ layer.

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 aluminum-tri-sec-butoxide and 2.47 ml zirconium butoxide in 15 ml 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 the titration, the suspension was stirred for another 30 minutes. The mixture was filtered and the remaining solid particles were washed with DI water followed by 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 alternatively further annealing at 200 ° C. for 24 hours A pigment was obtained.

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

3 g of the 7-layer designed 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. An additional 0.15 ml of EDA diluted in 0.9 ml of DI water was weighed. After the 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 a CeO ₂ layer.

Thereafter, the pigment coated with CeO ₂ was diluted with 20 ml of ethanol in a 100 ml round bottom flask and stirred at room temperature. Next, a mixture of 0.66 g aluminum-tri-sec-butoxide and 2.47 ml zirconium butoxide in 15 ml 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 the 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 washed with IPA. The remaining solid particles were dried at 100 ° C. for 24 hours, or alternatively further annealed at 200 ° C. for 24 hours to obtain a seven-layer pigment having a CeO ₂ layer and a ZrO ₂ + Al ₂ O ₃ mixed layer.

<Procedure 8> Seven-layer pigment having _two layers of ZrO ₂ g of the seven-layer designed 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) dissolved in 10 ml of ethanol was titrated at a rate of 1 hour. At the same time, 1 ml of DI water diluted in 3 ml of ethanol was weighed. After the 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 alternatively further annealed at 200 ° C. for 24 hours to obtain a 7-layer pigment having a ZrO ₂ layer.
<Step 9> the SiO ₂ coated pigment 2g of the SiO ₂ layer and _{the Al} 2 _{O 3} layer Coated with seven layers pigments Step 1 or 1A, having a pH of about 8 in 100ml round bottom flask (dilute NaOH solution Suspended in 20 ml of water (adjusted with Thereafter, 0.5 ml of 5 wt% NaAlO ₂ solution was titrated into the pigment suspension at a rate of 30 minutes. The pH of the slurry was adjusted to 8 using 1M HCl solution. After titration, the suspension was left for 30 minutes with stirring. The mixture was filtered and washed with DI water followed by IPA. The coated pigment was obtained by drying at 100 ° C. for 24 hours.

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

The weathering properties of the coated pigments were tested by the following method. Seven cylindrical 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 (1 × 10 −5 M) and 13.3 mg of pigment was tested. This pigment-eosin B solution was electromagnetically stirred under dark conditions for 30 minutes, and then exposed to light from a solar simulator (Oliol Sol2A class ABA solar simulator). For each pigment, the same type of pigment wrapped in aluminum foil was used as a direct standard control. In addition, commercial TiO ₂ (Degussa P25) was used as a reference to compare photocatalytic activity under similar experimental conditions. To detect the photocatalytic activity of each sample, a UV / Vis absorption spectrum after exposure to light for 65 hours was recorded.

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

Scanning electron microscope images of the seven-layer pigment before and after being coated 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 structure preservation after coating are the same as the pigment before coating. In addition, an EDX dot map image of a seven-layer omnidirectional structural color pigment in which the outer surface ZnS layer is coated with a first SiO ₂ layer and a second ZrO ₂ —Al ₂ O ₃ (Procedure 4) mixed layer protective coating Indicates that Zn, S, Si, Zr, and Al are concentrated relatively high in the coating structure.

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

  From the above, Table 4 provides various oxide layers, substrates that can be coated, and coating thickness ranges in the present teachings.

  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 process, 0.5 g of pigment having one or more protective layers as described above is added to a pH of about 5.0 (adjusted with dilute acetic acid solution) in a 100 ml round bottom flask. Suspended in 10 ml of EtOH / water (4: 1). The slurry was sonicated for 20 seconds and stirred at 500 rpm for 15 minutes. Next, 0.1-0.5 vol% organosilane added the chemical to the slurry and the solution was stirred at 500 rpm for an additional 2 hours. The slurry was centrifuged using DI water or filtered, 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 using DI water and then IPA or filtered to obtain a cake of pigment particles. Finally, the cake was dried at 100 ° C. for 12 hours.

  The organosilane process can use any organosilane coupling agent known to those skilled in the art, such as 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 illustrative purposes only, and variations, modifications, and the like apparent to those skilled in the art are within the scope of the present invention. Accordingly, the scope of the invention is defined by the claims and all equivalents thereof.

The present invention further includes the following embodiments:
1. A pigment having a first layer of a first material and a second layer of a second material, wherein the second layer extends across the first layer and exposes the pigment to broadband electromagnetic radiation. And when viewed from an angle between 0 ° and 45 °, the pigment has a given full width at half maximum (FWMH) less than 300 nm and a given color shift less than 30 ° in the CIELAB color space. A pigment reflecting the band and a weathering coating covering the outer surface of the pigment, and reducing the photocatalytic activity of the pigment by at least 50% compared to the pigment without the weathering coating An omnidirectional structural color pigment having a weather resistant coating.
2. 3. The omnidirectional structural color pigment having a protective coating as described in 2 above, wherein the weather-resistant coating has an oxide layer.
3. 3. The omnidirectional structural color pigment having a protective coating according to 2, wherein the oxide layer is selected from the group consisting of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, and cerium oxide.
4). The protective coating of 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. An omnidirectional structural color pigment.
5). 5. The omnidirectional structural color pigment having a protective coating according to 4, wherein the second oxide layer is a mixed oxide layer that 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; 6. An omnidirectional structural color pigment having a protective coating according to claim 5.
7). The omnidirectional structural color pigment having a protective coating according to 1, wherein the pigment does not include an oxide layer.

The present invention further includes the following embodiments:
1. A pigment having a first layer of a first material and a second layer of a second material, wherein the second layer extends across the first layer and exposes the pigment to broadband electromagnetic radiation. And when viewed from an angle between 0 ° and 45 °, the pigment reflects a band of electromagnetic radiation having a given half-width (FWMH) less than 300 nm and a given color shift less than 30 °. A weathering coating covering the pigment and the outer surface of the pigment and reducing the photocatalytic activity of the pigment by at least 50% compared to the pigment without the weathering coating An omnidirectional structural color pigment having a protective coating.
2. The omnidirectional structural color pigment having a protective coating according to 1 above, wherein the weatherable coating has an oxide layer.
3. 3. The omnidirectional structural color pigment having a protective coating according to 2, wherein the oxide layer is selected from the group consisting of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, and cerium oxide.
4). 4. The protective coating of claim 3, wherein the weatherable coating has a first oxide layer and a second oxide layer, and the second oxide layer is different from the first oxide layer. An omnidirectional structural color pigment.
5. 5. The omnidirectional structural color pigment having a protective coating according to 4, wherein the second oxide layer is a mixed oxide layer that is a combination of two different oxides.
6). The first oxide layer is silicon oxide, and the second oxide layer is at least two of the group consisting of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, and cerium oxide, 6. An omnidirectional structural color pigment having a protective coating according to claim 5.
7). The omnidirectional structural color pigment having a protective coating according to 1, wherein the pigment does not include an oxide layer.
8). Providing a plurality of pigment particles, wherein 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 the first layer; The pigment is exposed to broadband electromagnetic radiation and has a given full width at half maximum (FWMH) less than 300 nm and 30 ° when viewed from an angle between 0 ° and 45 °. Suspending a plurality of said pigment particles reflecting a band of electromagnetic radiation having a smaller given color shift in a first liquid to form a pigment suspension; a second liquid; and silicon, aluminum, zirconium Supplying an oxide precursor having an oxide constituent selected from cerium and titanium, mixing a pigment suspension and an oxide precursor, wherein the mixing is performed on a plurality of the pigment particles. Deposit a weathering oxide coating on the Compared with a plurality of pigment particles having a weather resistant coating, comprising decreasing the photocatalytic activity of a plurality of said pigment particles at least 50%, omnidirectional structural color manufacturing method of a pigment having a protective coating.
9. 9. The method according to 8, wherein the first liquid is a first organic solvent and the second liquid is a second organic solvent.
10. 10. The method according to 9 above, wherein the first organic solvent and the second organic solvent are organic polar solvents.
11. 11. The method according to 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.
12 12. The method according to 11 above, wherein the first organic solvent and the second organic solvent are protic organic polar solvents.
13. 13. The method according to 12 above, wherein the first organic solvent and the second organic solvent are the same protic organic polar solvent.
14 Silicon that is an oxide constituent element is in the form of tetraethoxysilane, and aluminum that is an oxide constituent element is at least one of aluminum sulfate and aluminum-tri-sec-butoxide, and is an oxide constituent element. Zirconium is in the form of zirconium butoxide, the cerium oxide constituent element is at least one of cerium nitrate hexahydrate and cerium sulfate, and the titanium oxide constituent element is titanium ethoxide. 14. The method according to 13 above, which may be in the form of at least one of titanium isopropoxide, and titanium-n-butoxide.
15. 9. The method according to 8 above, wherein the first liquid is a first aqueous liquid and the second liquid is a second aqueous liquid.
16. The oxide constituent element is in the form of sodium silicate, and the oxide constituent aluminum is at least one of aluminum sulfate, aluminum sulfate hydrate, and sodium aluminate, and the oxide constituent element A certain zirconium is in the form of zirconium chloride octahydrate, the cerium oxide constituent is in the form of cerium nitrate hexahydrate, and the titanium constituent oxide is in the form of titanium tetrachloride. 16. The method according to 15 above.

Claims (16)

A pigment having a first layer of a first material and a second layer of a second material, wherein the second layer extends across the first layer and exposes the pigment to broadband electromagnetic radiation. And when viewed from an angle between 0 ° and 45 °, the pigment reflects a band of electromagnetic radiation having a given half-width (FWMH) less than 300 nm and a given color shift less than 30 °. A weathering coating covering an outer surface of the pigment and reducing the photocatalytic activity of the pigment by at least 50% compared to the pigment without the weathering coating An omnidirectional structural color pigment having a protective coating.   The omnidirectional structural color pigment with protective coating according to claim 1, wherein the weatherable 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 of 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. An omnidirectional structural color pigment having a coating.   The omnidirectional structural color pigment with protective coating according to claim 4, wherein the second oxide layer is a mixed oxide layer that 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 of the group consisting of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, and cerium oxide; 6. An omnidirectional structural color pigment having a protective coating according to claim 5.   The omnidirectional structural color pigment with protective coating according to claim 1, wherein the pigment does not comprise an oxide layer. Providing a plurality of pigment particles, wherein 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 the first layer; The pigment is exposed to broadband electromagnetic radiation and has a given full width at half maximum (FWMH) less than 300 nm and 30 ° when viewed from an angle between 0 ° and 45 °. Suspending a plurality of said pigment particles in a first liquid reflecting a band of electromagnetic radiation having a smaller given color shift to form a pigment suspension;
Providing an oxide precursor having a second liquid and an oxide constituent selected from silicon, aluminum, zirconium, cerium and titanium;
Mixing a pigment suspension and an oxide precursor, wherein the mixing deposits a weatherable oxide coating on the plurality of pigment particles, as compared to a plurality of pigment particles having a weatherable coating; Reducing the photocatalytic activity of the plurality of pigment particles by at least 50%.   The method of 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 of 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.   The method according to claim 11, wherein the first organic solvent and the second organic solvent are protic organic polar solvents.   13. The method of claim 12, wherein the first organic solvent and the second organic solvent are the same protic organic polar solvent.   Silicon that is an oxide constituent element is in the form of tetraethoxysilane, and aluminum that is an oxide constituent element is at least one of aluminum sulfate and aluminum-tri-sec-butoxide, and is an oxide constituent element. Zirconium is in the form of zirconium butoxide, the cerium oxide constituent element is at least one of cerium nitrate hexahydrate and cerium sulfate, and the titanium oxide constituent element is titanium ethoxide. 14. The method of claim 13, which may be in at least one form of titanium isopropoxide, and 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 aluminum is at least one of aluminum sulfate, aluminum sulfate hydrate, and sodium aluminate, and the oxide constituent element A certain zirconium is in the form of zirconium chloride octahydrate, the cerium oxide constituent is in the form of cerium nitrate hexahydrate, and the titanium constituent oxide is in the form of titanium tetrachloride. 16. The method of claim 15, wherein