High performance signal compatible solar control film

Abstract

Disclosed is a solar control film comprising a first dielectric stack having alternating layers of high and low refractive index materials of a first equal optical thickness and at least one layer that is an odd multiple of the first equal optical thickness, the first dielectric stack having a reflection band centered at wavelengths between 800 nm and 1500 nm, and a second dielectric stack optically adjacent to the first dielectric stack, the second dielectric stack having alternating layers of high and low refractive index materials of a second equal optical thickness and at least a single layer that is an even multiple of the second equal optical thickness.

Description

[Background technology]

[0001]

[0001] Currently, there is a need for solar control films based on reflection technology that are highly transparent in the visible range and compatible with high frequency transmission from electronic devices. Electronic device compatibility is a very important factor in window film products. Currently, the best-performing commercial solar reflectors are based on multi-layer films that contain a silver layer. However, due to RF signal blocking, compatibility with current electronic devices is not sufficient.

[0002]

[0002] High performance window films based on selective absorption technology are also available, however, they perform poorly compared to metal-based reflectors because the absorbed solar energy is re-radiated on both sides of the glazing.

[0003]

[0003] Dielectric solar control films based on infrared reflectors (IRR) are also available. A typical dielectric IRR is constructed from a quarter-wave stack of optical materials with high and low refractive indices tuned to reflect bands in the NIR section of the solar energy spectrum. These dielectric IRRs have a limited width of reflection band and are difficult to construct. The IRR bands typically cover a narrow section of the NIR that is part of the solar spectrum.

[0004]

[0004] US Patent No. 3,279,317 discloses extending the effective range of a heat reflecting filter towards longer waves and further narrowing the gap present in the effective radius of the heat reflecting filter to the minimum wavelength of glass absorption at approximately 2.5μ. This reference is particularly concerned with heat rays generated by lamps, which are sources of low color temperature. According to this disclosure, the width of the transmission (or low reflection) band is limited to approximately 280 nm in the visible light spectrum. This disclosure is not an issue for projection systems, since it is concerned with eliminating the heat rays of lamps, and not with infrared reflectors for solar control, which are seen at large angles of incidence, such as 30 degrees or 45 degrees. The spectrum of dielectric reflectors is known to be shifted towards the "blue" side, and therefore such a narrow transmission width results in a significant amount of visible light reflection, coloration and degradation of Tvis at large angles of incidence. See FIG. 1. FIG. 1 shows the reflectance spectrum of U.S. Pat. No. 3,279,317, as modeled on information provided in that patent, and shows that at the 45 degree incidence angle shown in that patent, a portion of the reflectance is significantly shifted into the visible region, relative to a 0 degree incidence angle.

[0005]

[0005] The NIR reflection range can be extended by using additional interference stacks centered at different wavelengths in the NIR. However, the additional reflection peak also produces a secondary peak in the visible range, causing a narrow transmission band that is not suitable for wide viewing angles. This effect can be seen in Figures 2 and 3, and as shown in Figure 4, where two peaks at 950 nm and 1300 nm overlap. The width of the TR in Figure 4 is approximately 300 nm, resulting in significant reflection in the visible range. Summary of the Invention [Problem to be solved by the invention]

[0006]

[0006] It would be highly advantageous to have a dielectric reflector for wide viewing angles, targeting the solar NIR range, that has solar reflective performance similar to metallic reflectors, but allows RF signals for electronic devices to pass through. [Means for solving the problem]

[0007] In various aspects, the invention described and claimed herein comprises an infrared reflective film or solar control film, which is useful, for example, for blocking infrared energy.

[0008] In one aspect, the present invention relates to an infrared reflective and solar control film comprising a first dielectric stack having alternating layers of high and low refractive index materials of equal optical thickness, and at least one layer that is an odd multiple of equal optical thickness, and having a reflection band centered at a wavelength of 850 nm to 1250 nm. The infrared reflective film of the present invention further comprises a second dielectric stack optically adjacent to the first dielectric stack, the second dielectric stack having alternating layers of high and low refractive index materials of equal optical thickness, and at least one layer that is an even multiple of equal optical thickness, resulting in a double-peak reflection band that is wider than the reflection band of the first dielectric reflector stack and exhibits both a first peak and a second peak in the wavelength range of 800 nm to 1500 nm. The infrared reflective film of the present invention may, for example, reflect at least 30% of electromagnetic radiation over the wavelength range of 850 nm to 1500 nm. In another embodiment, the infrared reflective film may reflect at least 30% of electromagnetic radiation over the 600 nm wavelength range. In a further embodiment, the infrared reflective film may transmit at least 85% of high frequency wavelengths.

[0009] Further aspects of the invention are disclosed and claimed herein. [Brief description of the drawings]

[0010] [Figure 1]

[0010] FIG. 1 is a graph showing the reflectance spectrum modeled in information provided in U.S. Pat. No. 3,279,317, where as the angle of incidence shifts from normal to 45 degrees, a typical viewing angle for glazing, some of the reflectance shifts significantly into the visible region. [Diagram 2]

[0011] 1 is a graph showing undesirable higher order peaks in the visible spectrum due to optical interference effects when using a reflector stack of equal optical thickness with a central peak at a higher wavelength that can be used to make the reflection peak broader. [Diagram 3]

[0012] 1 is a graph showing reflectors tuned to 1050 nm and 1300 nm, respectively, showing an undesirable reflection peak in the visible range that appears when the reflector is tuned to 1300 nm. [Figure 4]

[0013] 4 is a graph showing a broad area reflector based on a continuous reflection band when two stacks from FIG. 3 are combined. [Diagram 5]

[0014] 1 is a graph showing an example of how a single peak reflection band can be modified to create multiple peak reflection bands by adding a center layer that is twice the width of the other layers. [Figure 6]

[0015] 1 is a graph showing three reflectance spectra: a single peak, multiple peaks, and a single peak and a double peak that can be combined by stacking two layers into a single broadband reflectance structure. [Figure 7]

[0016] 1 is a graph showing an example with calculated performance values ​​for a laminate according to the present invention. [Figure 8]

[0017] 1 is a graph showing a single peak reflectance spectrum from a prototype. [Figure 9]

[0018] 1 is a graph showing multiple peak reflectance spectra from a prototype. [Figure 10]

[0019] 13 is a graph comparing the effectiveness of the engineered compound with the results obtained from the prototype in each of the two sections. [Figure 11]

[0020] 13 is a graph comparing the total reflectance of compound designs with results from prototypes. [Figure 12]

[0021] 1 is a graph showing the reflectance spectra of a multi-peak reflector for even and odd thicknesses. [Figure 13]

[0022] Graph showing examples of combining multiple peaks: 2x and 5x combinations. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011]

[0023] Thus, in one aspect, the present invention relates to an infrared reflective or solar control film comprising a first dielectric stack and a second dielectric stack. The first dielectric stack has alternating layers of high and low refractive index materials of equal optical thickness, and at least one layer that is an odd multiple of equal optical thickness. The first dielectric stack has a reflection band centered, for example, between 850 nm and 1250 nm when the multiple is 1, or between 850 and 1500 when the multiple is 3 or 5.

[0012]

[0024] The film of the present invention may further comprise a second dielectric stack optically adjacent to the first dielectric stack, the second dielectric stack having alternating layers of high and low refractive index materials of equal optical thickness and at least a single layer that is an even multiple of equal optical thickness, resulting in a double peak reflection band that is wider than the reflection band of the first dielectric reflector stack and exhibits both a first peak and a second peak, for example, in the wavelength range of 800 nm to 1500 nm. The infrared reflective film of the present invention may reflect at least 30% of electromagnetic radiation over a wavelength range of, for example, 800 nm to 1500 nm and transmit at least 70% of electromagnetic radiation over a wavelength range of 400 nm to 750 nm. The infrared reflective film may reflect at least 30% of electromagnetic radiation over a wavelength range of 600 nm.

[0013]

[0025] As already mentioned, the optical thickness of the layers of these dielectric stacks is adjusted to about a quarter wavelength of the peak in the NIR, or a multiple thereof. If these stacks are adjusted to provide substantial transmission in the visible range, they may have a small but significant reflection in the visible range. It may be necessary to adjust the reflected color without significantly changing either the NIR reflection or the visible transmission.

[0014]

[0026] For example, in a windshield, the reflection color at various angles of incidence should be different and neutral or lightly colored. The reflection color may be seen as small ripples in the visible portion of the reflection spectrum. As described, the thickness of the layers in the stack is substantially close to a quarter wavelength or a multiple thereof to contribute to NIR reflection. However, the thickness of the layers may deviate by a small amount to adjust the reflection spectrum in the visible region and therefore the reflection color.

[0015]

[0027] Color tuning at various angles of incidence can also be obtained by additional layers substantially thinner than a quarter wavelength thick to adjust the visible reflection without affecting the NIR reflection. The additional layer or layer pair should typically be less than about an eighth wavelength (less than about 90 nm) or less than about a sixteenth wavelength (less than about 45 nm). The refractive index of the material should provide a refractive index contrast, with a high refractive index layer following a low refractive index layer and a low refractive index layer following a high refractive index layer. Precise thickness tuning of the layers can be obtained by computer refinement. In such an embodiment, as few as one or two layers with different refractive indices may be used.

[0016]

[0028] The following embodiments and combinations are within the scope of the present invention. 1. A solar control film comprising: a first layer of alternating high and low refractive index materials of equal optical thickness; and At least one layer having an odd multiple of the first equal optical thickness a first dielectric stack having a reflection band centered at a wavelength between 800 nm and 1500 nm; a second dielectric stack optically adjacent to the first dielectric stack; a second equal optical thickness of alternating layers of high and low refractive index materials; and at least a single layer that is an even multiple of a second equal optical thickness, resulting in a dual-peak reflection band that is at least as wide as the reflection band of the first dielectric reflector stack and that exhibits both a first peak and a second peak in the wavelength range of 800 nm to 1500 nm; a second dielectric stack having Including, solar control films. 2. The solar control film of embodiment 1, which reflects at least 30% of electromagnetic radiation over the wavelength range of 850 nm to 1500 nm. 3. The solar control film of any of the previous embodiments, which reflects at least 30% of electromagnetic radiation over the 600 nm wavelength range. 4. A solar control film of any of the preceding embodiments, which transmits at least 85% of high frequency wavelengths. 5. A solar control film according to any of the preceding embodiments, wherein a peak of the reflection band of the first dielectric stack is between the first and second peaks of the reflection band of the second dielectric stack. 6. A solar control film of any of the preceding embodiments, which transmits at least 90% of high frequency wavelengths. 7. The solar control film of any of the preceding embodiments, exhibiting a Tvis of at least 70%. 8. The solar control film of any of the preceding embodiments, wherein the odd multiple of the first equal optical thickness is a multiple selected from 1, 3, 5, 7 or 9. 9. The solar control film of any of the preceding embodiments, wherein the even multiple of the second equal optical thickness is a multiple selected from 2, 4, 6, 8, or 10. 10. The solar control film of any of the preceding embodiments, wherein at least one layer that is an odd multiple of the first equal optical thickness is a unity optical thickness. 11. The solar control film of any of the preceding embodiments, wherein a single layer that is an even multiple of a second equal optical thickness is twice the equal optical thickness. 12. The solar control film of any of the preceding embodiments, which reflects at least 40% of electromagnetic radiation over the wavelength range of 800 nm to 1500 nm. 13. The solar control film of any of the preceding embodiments, which reflects at least 45% of electromagnetic radiation over the wavelength range of 800 nm to 1500 nm. 14. The solar control film of any of the preceding embodiments, which reflects at least 50% of electromagnetic radiation over the wavelength range of 800 nm to 1500 nm. 15. The solar control film of any of the preceding embodiments, exhibiting a Tvis of at least 80%. 16. The solar control film of any of the preceding embodiments, exhibiting a Tvis of at least 90%. 17. The solar control film of any of the preceding embodiments, wherein the first dielectric reflector stack and the second dielectric reflector stack are deposited on the same substrate. 18. The solar control film of any of the preceding embodiments, wherein the first dielectric reflector stack and the second dielectric reflector stack are deposited on separate substrates that are laminated to form the solar control film. 19. The solar control film of any of the previous embodiments, wherein the first dielectric reflector stack comprises 3 to 11 layers. 20. The solar control film of any of the preceding embodiments, wherein the second dielectric reflector stack includes 5 to 11 layers, and a single layer that is an even multiple of the second equal optical thickness is one of the three intermediate layers. 21. The solar control film of any of the previous embodiments, wherein the broadband reflective film exhibits at least 20% solar reflectance. 22. The solar control film of any of the preceding embodiments, wherein the layer of high refractive index material has a refractive index of at least 2. 23. The solar control film of any of the preceding embodiments, wherein the layer of low refractive index material has a refractive index less than 1.5. 24. The solar control film of any of the previous embodiments, wherein the layer of high refractive index material comprises one or more of titanium oxide, niobium oxide, indium oxide, tantalum oxide, zinc sulfide, gallium nitride. 25. The solar control film of any of the previous embodiments, wherein the layer of low refractive index material comprises one or more of silicon dioxide, magnesium fluoride, or calcium fluoride. 26. The solar control film of any of the preceding embodiments, which reflects at least 70% of electromagnetic radiation over a wavelength range of about 850 nm to about 1350 nm in the infrared and reflects at least 50% of electromagnetic radiation over a wavelength range of about 800 nm to about 1500 nm in the infrared. 27. The solar control film of any of the preceding embodiments, wherein the repeating layers of high and low refractive index materials of the first dielectric reflector stack are polymer layers. 28. The solar control film of any of the previous embodiments, wherein at least one of the first dielectric reflector stack and the second dielectric reflector stack comprises an inorganic layer. 29. The solar control film of any of the previous embodiments, further comprising one or more of a UV absorber, an IR absorber, or a UV blocker. 30. The solar control film of any of the preceding embodiments, further comprising an attachment adhesive layer. 31.c) The solar control film of any of the preceding embodiments, further comprising a color correction layer comprising at least two alternating layers of high and low refractive index, each layer having an optical thickness of less than about one-eighth wavelength thick. 32.c) The solar control film of any of the preceding embodiments, further comprising a color correction layer comprising at least two alternating layers of high and low refractive index, each layer having an optical thickness of less than about one-sixteenth wavelength thick.

[0017]

[0029] Thus, the present invention relates to an infrared reflective film that may include a first dielectric stack having alternating layers of high and low refractive index materials of equal optical thickness, and at least one layer that is an odd multiple of equal optical thickness. The first dielectric stack has a reflection band centered, for example, at wavelengths between 800 nm and 1500 nm, or between 850 nm and 1500 nm, or between 900 nm and 1400 nm. The infrared reflective film of the present invention may further include a second dielectric stack optically adjacent to the first dielectric stack, having alternating layers of high and low refractive index materials of equal optical thickness, and a single layer that is an even multiple of equal optical thickness, resulting in a multi-peak reflection band that is broader than, and therefore complementary to, the reflection band of the first dielectric reflector stack, for example exhibiting a peak at a position in the wavelength range of 800 nm to 1500 nm. The infrared reflective film of the present invention may reflect at least 35% of electromagnetic waves over the wavelength range of 800 nm to 1500 nm, or 850 nm to 1500 nm, or 900 to 1400 nm, and may transmit at least 70% of electromagnetic waves over the wavelength range of 400 nm to 750 nm.

[0018]

[0030] The invention also relates to an infrared reflective film that may include a first dielectric stack having alternating layers of high and low refractive index materials of equal optical thickness, e.g., having a reflection band centered at wavelengths from 850 nm to 1250 nm, and a second dielectric stack having alternating layers of high and low refractive index materials, each layer of the alternating layers being twice the optical thickness of the other layer of equal optical thickness, resulting in a dual-peak reflection band that is wider than the reflection band of the first dielectric reflector stack, exhibiting both a first peak and a second peak in the wavelength range of, e.g., 800 nm to 1500 nm.

[0019]

[0031] The films of the present invention may reflect at least 30%, or at least 35%, or at least 40%, or at least 50%, or at least 60%, or at least 70% of electromagnetic radiation over the wavelength range of 800 nm to 1500 nm. The infrared reflective film may transmit at least 85% of the wavelengths that are greater than about 6 mm in the high frequency region, or at least 90% of the wavelengths in the high frequency region, or at least 95%, or at least 99% of the wavelengths in the high frequency region.

[0020]

[0032] The first and second dielectric reflector stacks may be deposited on the same substrate, or the first and second dielectric reflector stacks may be deposited on separate substrates and laminated together to form the infrared reflective film.

[0021]

[0033] The first dielectric reflector stack and the second dielectric stack may each include, for example, 3 to 11 layers, or 5 to 9 layers. The number of layers in each of the two stacks may be the same or different. Furthermore, the layers that are multiples of the optical thickness may be layers 5, 6 or 7, for example for a total of 11 layers. Typically, the number of layers is an odd number of layers, and the layers that are multiples of the optical thickness may be near or at the middle layer.

[0022]

[0034] In accordance with the present invention, the infrared reflective film is typically substantially transparent to visible light, e.g., exhibiting a Tvis of at least 50%, or at least 75%, or at least 85%, or at least 90%, or at least 95%.

[0023]

[0035] According to the present invention, the infrared reflective film blocks a significant amount of solar energy, for example having a TSER of at least 60%, or at least 40%, or at least 30%. TSER is the "total solar energy blocked" and is the percentage of solar energy blocked from passing through the glazing. TSER is calculated from the solar reflection and solar absorption spectra as a normalized weighted average through the glazing, the weighting function being the solar energy spectrum according to ASTM E-891. Solar reflection is calculated from the solar reflection spectrum as a normalized weighted average from the emitting side of the glazing, the weighting function being the solar energy spectrum according to ASTM E-891. TSER is the calculated solar reflection plus the fraction of solar absorption that is not re-radiated inwards, and is calculated according to the National Fenestration Rating Council NFRC 300 test method for determining the solar optical properties of glazing. TSER can be enhanced by the addition of IR absorbers, which absorb the solar energy that is not reflected.

[0024]

[0036] The infrared reflective films of the present invention may employ high refractive index materials, for example having a refractive index of at least 1.9, or at least 2, or at least 2.2.

[0037] The infrared reflective films of the present invention may also use low refractive index materials, for example having a refractive index less than 1.4, or less than 1.5, or less than 1.6.

[0025]

[0038] Examples of high refractive index materials useful in accordance with the present invention include one or more of indium oxide, niobium oxide, titanium oxide, zinc sulfide, tantalum oxide, gallium nitride, mixed compounds, and the like.

[0026]

[0039] Further examples of low refractive index materials useful in accordance with the present invention include one or more of silicon dioxide, magnesium fluoride, calcium fluoride, and the like.

[0040] According to the present invention, an infrared reflective film may, for example, reflect at least 70% of electromagnetic radiation over a wavelength range of 850 to 1350 nm in the infrared, or at least 50% of electromagnetic radiation over a wavelength range of about 800 nm to about 1500 nm in the infrared.

[0027]

[0041] The repeating layers of high and low refractive index materials in the first dielectric reflector stack may be polymer layers. At least one of the first and second dielectric reflector stacks may include an inorganic layer.

[0028]

[0042] The IR reflective films of the present invention may have an Rsol, or solar reflectance, of at least 20%, or at least 25%, or at least 30%, or at least 35% of the solar energy that contacts the film. Rsol, or solar reflectance, is the percentage of solar energy that is reflected away from the glazing. Rsol is calculated from the solar reflectance spectrum as a normalized weighted average of the glazing passes, where the weighting function is the solar energy spectrum according to ASTM E-891. Solar reflectance is calculated according to the National Fenestration Rating Council NFRC 300 test method for determining the solar optical properties of glazing.

[0029]

[0043] The present invention relates to solar control films that may include solar control particles, for example, provided in or on a substrate, for example, in a solar absorber layer, an adhesive layer, or elsewhere in the inventive film. The solar absorber layer is optically or functionally adjacent to the dielectric stack layer, meaning that both light and electromagnetic waves pass through to achieve a desired function.

[0030]

[0044] These solar control particles may, for example, include one or more of various inorganic metal compounds, particularly borides, nitrides, or oxides, which may be dispersed in a resin binder to form a coating that reflects or absorbs specific wavelength bands of infrared energy and transmits visible light at high levels. In particular, U.S. Patent No. 6,663,950, the relevant disclosure of which is incorporated herein by reference, discloses that antimony-doped tin oxide (ATO) has very low transmission to infrared light having wavelengths greater than 1400 nm, and U.S. Patent No. 5,518,810, the relevant disclosure of which is incorporated herein by reference, discloses a coating containing tin-doped indium oxide (ITO) particles that substantially blocks infrared light having wavelengths greater than 1000 nm, but the crystal structure of the ITO particles can be modified to block light having wavelengths between 700 and 900 nm. No. 6,060,154, the relevant disclosure of which is incorporated herein by reference, discloses the use of fine particles of ruthenium oxide, tantalum nitride, titanium nitride, titanium silicide, molybdenum silicide, and lanthanum boride to block light in the near infrared region. It also discloses the use of several different films, each of which selectively transmits light.

[0031]

[0045] Nanoparticles, as used herein, are useful according to the present invention and refer to particles generally having an average particle size of 200 nm or less, or less than 100 nm, or between 10 nm and 400 nm, or between 30 nm and 150 nm, or between 50 nm and 200 nm.

[0032]

[0046] In one embodiment, the solar control particles may be one or more of antimony tin oxide (ATO), indium tin oxide (ITO) or tin oxide, or doped variants thereof. Thus, the nanoparticles may comprise ATO, and the coating layer applied to the substrate may contain, for example, 30-60% by weight ATO, or 50-60% by weight ATO. The concentration of particles is typically selected to provide absorption of solar energy in the NIR range, and solar performance is measured as TSER. The amount of particles is measured as areal density (grams per square meter). For example, about 1-9 g / m2 of ATO particles provides a TSER of about 20% to about 40%.

[0033]

[0047] Alternatively or additionally, the solar control particles may include modified ITO, e.g., as described in U.S. Pat. No. 5,807,511, the relevant disclosure of which is incorporated herein by reference, and / or at least one of a metal hexaboride taken from the lanthanide series of the periodic table, with preferred hexaborides being La, Ce, Pr, Nd, Gb, Sm and Eu, with La being the most preferred choice.

[0034]

[0048] When a coating layer is used, the binder may be a thermoplastic resin, such as an acrylic resin, a thermosetting resin, such as an epoxy resin, an electron beam curable resin, or preferably an acrylate resin of the type disclosed in U.S. Pat. No. 4,557,980, the relevant disclosure of which is incorporated herein by reference, a UV curable resin, or preferably a urethane acrylate resin.

[0035]

[0049] This layer is non-electrically conductive, making it particularly useful for applications involving automobile windshields or rear windows, especially those that contain radio antennas.

[0050] This layer is coated onto a transparent polymeric film substrate, preferably a polyester film, which is more preferably a polyethylene terephthalate (PET) film. The solar absorbing or infrared blocking coating forms a hard coat for the film substrate, which is particularly advantageous and can eliminate further processing steps during composite film manufacture. The PET film can be coated with an adhesive to secure the film composite to an existing window, for example, in a building or automobile. The PET film and / or adhesive may include at least one uv radiation absorbing material to block substantially all uv radiation, down to less than 1% weighted UV transmission.

[0036]

[0051] Alternatively or additionally, the solar control particles may include those particles disclosed and claimed in, for example, U.S. Patent No. 8,083,847, the relevant disclosure of which is incorporated herein by reference. Thus, in accordance with the present invention, a fine particle dispersion may be used that has visible light transparency and is formed by dispersing fine particles of an infrared shielding material in a medium, the fine particles of the infrared shielding material having the general formula M x W y O z wherein M is at least one element selected from the group consisting of H, alkali metals, alkaline earth metals, rare earth elements, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, I, and mixtures thereof, W is tungsten, and O is oxygen, and is represented by the general formula M x W y O zmay satisfy 0.001≦x / y≦1 and 2.2z / y≦3.0, the particle diameter of the infrared shielding material may be, for example, 1 nm or more and 800 nm or less, and the medium is a resin, typically a resin deposited on or in a substrate. In one embodiment, the particles may include cesium-doped tungsten oxide.

[0037]

[0052] These fine particles may include at least one fine particle of hexagonal, tetragonal or cubic structure, typically hexagonal structure.

[0053] According to the above, the element M may be at least one of Cs, Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe and Sn, and the fine particles may be coated with an oxide containing at least one element selected from the group consisting of Si, Ti, Zr and Al.

[0038]

[0054] The medium may be a resin containing at least one polymer selected from the group consisting of polyethylene resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl alcohol resin, polystyrene resin, polypropylene resin, ethylene-vinyl acetate copolymer, polyester resin, polyethylene terephthalate resin, fluororesin, polycarbonate resin, acrylic resin, and polyvinyl butyral resin.

[0039]

[0055] The dispersion can be formed by dispersing fine particles of an infrared shielding material in a medium. The fine particles of the infrared shielding material are represented by the general formula M x W y O zwherein M is at least one element selected from the group consisting of H, He, alkali metals, alkaline earth metals, rare earth elements, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, I, and mixtures thereof, W is tungsten, and O is oxygen, and the method includes the step of heating a starting material for the infrared shielding material fine particles in a reducing gas and / or inert gas atmosphere.

[0040]

[0056] The starting material for the fine particles of the infrared shielding material may be heated, for example, in a reducing gas atmosphere at 100°C to 850°C, and then heated in an inert gas atmosphere at 650°C to 1200°C. x W y O z The starting material for the fine particles of the tungsten oxide complex represented by may be a powder obtained by mixing a powder of element M or a compound containing element M with two or more of the following powders selected from the group consisting of tungsten trioxide powder, tungsten dioxide powder, tungsten oxide hydrate powder, tungsten hexachloride powder, ammonium tungstate powder, tungsten oxide hydrate powder obtained by dissolving tungsten hexachloride in alcohol and then drying the solution, tungsten oxide hydrate powder obtained by dissolving tungsten hexachloride in alcohol, adding water to the solution to form a precipitate and drying the precipitate, tungsten compound powder obtained by drying an aqueous solution of ammonium tungstate, and metallic tungsten powder. This powder can be obtained, for example, by mixing an alcohol solution of tungsten hexachloride or an aqueous solution of ammonium tungstate with a solution of a compound containing element M and drying the mixture.

[0041]

[0057] For example, the powder can be obtained by mixing a powder of either element M or a compound containing element M, or a solution of a compound containing element M, with a dispersing solution obtained by dissolving tungsten hexachloride in alcohol and adding water to the solution to form a precipitate; and drying the mixture.

[0042]

[0058] Other solar control particles and coating layers useful according to the invention include those disclosed in U.S. Patent No. 7,585,436. Thus, the solar absorbing layer may comprise a poly(ethylene terephthalate) film containing lanthanum hexaboride and an epoxy agent, such as one selected from diepoxides of poly(oxypropylene) glycol, 2-ethylhexyl glycidyl ether, and diepoxide products of epichlorohydrin and polypropylene glycol. Lanthanum hexaboride particles useful according to the invention are present, for example, in an amount of about 0.01 to about 0.2 weight percent of the film, or in an amount of 0.01 to 0.15 weight percent of the film, or at an areal density of about 0.01 g / mt2 to about 0.25 g / mt2.

[0043]

[0059] The preparation of lanthanum hexaboride and its incorporation into or onto polymeric substrates is well known in the art (see, for example, U.S. Patent Nos. 6,620,872 and 6,911,254).Lanthanum hexaboride is available, for example, as a dispersion of solid particles in a liquid, optionally including zirconium and a dispersing agent.

[0044]

[0060] Lanthanum hexaboride can be incorporated into the polymeric film of the present invention in any suitable amount, and is generally incorporated in an amount sufficient to provide the desired near infrared absorbance without excessively affecting optical performance. In various embodiments, lanthanum hexaboride can be incorporated into the film in an amount of, for example, 0.01-0.2 weight percent, 0.01-0.15 weight percent, or 0.01-0.1 weight percent, or 0.005-1.5 weight percent. In embodiments in which other infrared absorbing materials are used, the amount of lanthanum hexaboride can be appropriately reduced. Examples of other useful infrared absorbing materials include indium tin oxide and doped tin oxide, among others. In embodiments in which lanthanum hexaboride can be dispersed in the binder layer or hard coat, lanthanum hexaboride can be incorporated into the polymeric film in an amount of less than 3 weight percent, preferably less than 2%, and more preferably 0.5%-2%, in various embodiments.

[0045]

[0061] Lanthanum hexaboride can be incorporated into polymer films by directly mixing with polymeric precursors prior to film formation. Lanthanum hexaboride can be incorporated, for example, onto poly(ethylene terephthalate) films by spraying, gravure, or dipping techniques, among others. In other embodiments, lanthanum hexaboride can be incorporated into hard coat materials, as described in detail elsewhere herein. Hard coats are often used with polymer films to enhance scratch resistance and other characteristics (see, for example, U.S. Pat. No. 6,663,950). In other embodiments, lanthanum hexaboride can be incorporated into binder materials used to bond two polymer films together to form a multilayer film, as is well known in the art.

[0046]

[0062] Lanthanum hexaboride, and other particles useful in the present invention, can be nano-sized, for example, ground particles less than 250 nanometers, less than 200 nanometers, less than 150 nanometers, or less than 100 nanometers in size.

[0047]

[0063] Lanthanum hexaboride can be combined with antimony tin oxide, indium tin oxide or tin oxide and added to the binder layer or hard coat of a polymer film.

[0048]

[0064] Thus, antimony tin oxide may be used and the binder layer or hardcoat may contain 30-60 weight percent antimony tin oxide, or 50-60 weight percent antimony tin oxide, and less than 3 weight percent, or less than 2%, or 0.5% to 2% lanthanum hexaboride. The weight percent of lanthanum hexaboride may be, for example, 1.08% to 3.53% of the total weight percent of the sum of lanthanum hexaboride and antimony tin oxide.

[0049]

[0065] The IR reflective or solar control films of the present invention may further comprise one or more of a UV absorber, an IR absorber, or a UV blocker.

[0066] As used herein, the terms "infrared reflective film" and "solar control film" may be used interchangeably unless otherwise indicated.

[0050]

[0067] The term "dielectric stack" as used herein refers to alternating layers of optical coatings with different refractive indices, e.g. inorganic layers, that can be built on a polymer film. Alternatively, they can be stacks of polymers with alternating layers of different refractive indices. The interfaces between these layers produce phased reflections, selectively enhancing certain wavelengths of light and blocking others. These layers are typically applied by vacuum deposition. By controlling the thickness and number of layers, the wavelength of the passband of the filter can be tuned.

[0051]

[0068] Thus, the present invention relates to an infrared reflective film that may include a dielectric stack, described herein as a second dielectric stack, with alternating low-high refractive index and exhibiting a double (or multiple peak) reflection. The double or multiple peak reflection may be achieved by the use of one or more "modified" quarter-wave dielectric stacks, in which the low or high refractive index layers near the center are an even multiple of the optical thickness of the other layers of the stack. The inventors have found that, according to the present invention, when an even multiple of equal optical thickness is used, a double peak reflection occurs predominantly, with a wider range of reflection compared to the quarter-wave stack. This second dielectric stack may simply be laminated to a film with a single blocking peak (when the odd multiple is 1), a quarter-wave dielectric stack, described herein as a first dielectric stack, to form a multi-layer laminate film with a relatively broad near-infrared reflection band. Alternatively, the odd multiple may be, for example, 3, 5 or 7, in which case the number of peaks is also 3. In either situation, the first and second dielectric stacks may be deposited on the same substrate or may be deposited on separate substrates and then laminated together to provide a substantially broader reflection band in the NIR as compared to a quarter wave stack. As used herein, the term NIR generally refers to wavelengths from about 780 nm to about 2500 nm.

[0052]

[0069] The multi-layer laminate films of the present invention are an improvement over prior art broadband films that have successive reflector stacks with different central peak locations that can generate harmonics and produce undesirable secondary reflection peaks in the visible spectrum. The final construction can include infrared absorbers and other dyes to improve solar performance and / or to adjust visible light transmission and, optionally, color.

[0053]

[0070] Typical solar control coatings are based on the IR reflecting properties of metals, such as silver. Metals reflect a very wide range, including the entire NIR section of the solar spectrum. However, metals reflect well beyond the NIR, including high frequencies above 6 mm, and therefore block radio signals. Metals also reflect the visible section, and metals are typically used in conjunction with dielectrics to increase transmission in the visible range.

[0054]

[0071] In contrast, dielectrics typically have a lower reflection. Dielectric stacks are typically constructed to reflect a band centered on a given wavelength. The thickness is designed to constructively form a reflection band in the NIR region of the solar spectrum. A typical dielectric reflector is constructed by stacking quarter-wave transparent, high-contrast refractive index materials tuned to the NIR. The level of reflection and the width of the reflection peak are a function of the number of layers and also the refractive index contrast of the materials used. Even with the highest practical refractive index contrast, the width of the peak does not reach the NIR section of the solar spectrum. One solution is to place multiple successive reflector stacks with different central peak positions to broaden the reflection peak. However, as shown in Figure 2, due to optical interference effects, second or higher order reflection band harmonics are generated, causing undesirable secondary reflection peaks that belong to the visible section.

[0055]

[0072] When constructing a broadband reflector based on continuous reflection bands, we combine the two stacks from Figure 3 and obtain the spectrum shown in Figure 4. The reflector in Figure 4 has good solar reflection properties, however, there is also an undesirable reflection peak appearing in the visible region due to the 1300 nm tuned reflector from Figure 3.

[0056]

[0073] Thus, the present invention relates in part to the use of dual or multi-peak reflectors where performance is further improved by lamination with a dielectric stack having a single peak between the peaks of the multi-peak reflector, while maintaining sufficient transmission width in the visible region. The example in Figure 6 shows the basic construction with an increased overall width of the reflection band.

[0057]

[0074] It should be noted that the broader reflector shown in Figure 6 covers much of the solar energy radiation of interest because metal based reflectors typically have a greater IR reflectance. However, the construction becomes transparent above the wavelengths of interest of solar energy; i.e., transparent to RF signals. The wavelengths of interest are shown in Figure 7 compared to the solar energy spectrum for 70% visible light transmission according to the present invention.

[0058]

[0075] When we say that a dielectric stack can selectively reflect infrared or NIR light, we mean that it is designed to reflect wavelengths from about 700 nanometers and above, or from about 700 to about 2500 nm, or from 700 nm to 1750 nm, nominally the red end of the visible spectrum, i.e., beyond the visible light spectrum. A reflective layer that selectively reflects in this wavelength range is understood to block solar radiation, for example, because the reflected wavelengths do not enter an automobile and heat the interior.

[0059]

[0076] Thus, by "visible radiation" or "visible light" it is meant electromagnetic radiation having a wavelength between about 380 nanometers and about 750 nanometers, or between about 400 nanometers and about 700 nanometers, and by "infrared radiation" or "heat radiation" it is meant electromagnetic radiation having a wavelength greater than about 700 nanometers, or greater than about 750 nanometers, or as otherwise described herein.

[0060]

[0077] UV radiation may be considered to be electromagnetic radiation having a wavelength of about 100 to 400 nm, or 100 to 380 nm, or 100 nm to 315 nm.

[0078] "Transparent" means having the property of transmitting visible light, unless otherwise specified.

[0061]

[0079] "Tvis" or "Tv" or "visible transmittance" each refers to a measure of transmittance over the visible wavelengths. It is a combined term that covers the area under the transmittance versus the area under the wavelength curve over the visible wavelengths, weighted for the sensitivity of the human eye. (1931 CIE A Standard Optical Standard). For automotive windshield glazing, Tvis should be 70% or greater.

[0062]

[0080] "Tsol" or "Ts" or "solar transmittance" each refers to a measure of the transmittance over the wavelengths of all solar energy. (ASTM E 424A) This is a unified term that covers the area under the transmittance versus the area under the wavelength curve for both visible and infrared wavelengths. For many heat reflective films, and films incorporating glazing, the primary goal is to reduce Tsol while keeping Tvis as high as possible.

[0063]

[0081] A "permeable metal layer" is a homogeneous, coherent metal layer composed of silver, gold, platinum, palladium, aluminum, copper or nickel, and alloys thereof, of a thickness that allows substantial transparency. Permeable metal layers are known to block radio frequencies.

[0064]

[0082] A "transparent metal oxide layer" is a layer made from a compound of a metal reacted with oxygen; the metal oxide layer is typically transparent in the VIS and IR regions.

[0083] "Vacuum deposition" includes physical vapor deposition, chemical vapor deposition, plasma enhanced chemical vapor deposition, etc. "Sputter deposit" or "sputter deposited" refers to a physical vapor deposition process or the product of this process in which a layer of material is laid down by the use of a magnetron sputtering source, and "plasma enhanced chemical vapor deposition" (PECVD) refers to a process in which a layer material is laid down by chemical vapor deposition through the use of precursors and a plasma source.

[0065]

[0084] A "dielectric" is a non-metallic or inorganic material that is transparent to both visible and infrared radiation. Typically, these materials are inorganic oxides, but other materials, such as fluorides, sulfides, and organic polymers, may be included as well.

[0066]

[0085] "Optical thickness" as used herein is defined as the physical thickness of a layer multiplied by the refractive index of the material used. Optical thickness is related to the optical path length and is a function of the refractive index of the material, and therefore determines the phase of light passing through the material.

[0067]

[0086] "Continuous" has its ordinary meaning of actual contact, i.e., adjacent. Sometimes, for emphasis or clarity, the somewhat redundant term "directly contiguous" is used, but has the same meaning.

[0068]

[0087] By "adjacent" it is meant that the layers referred to are functionally adjacent to one another, especially optically adjacent, i.e., layers are adjacent if, for example, any layer between adjacent layers does not block the intended function, in this case, allowing light to pass through the layers, and light that is intended to pass through both layers does in fact pass through both layers.

[0069]

[0088] Thus, "optically adjacent" means that the layers function optically together, i.e., are arranged in one optical path. Thus, the term "optically adjacent" means that additional material may be placed between optically adjacent layers, so long as it is the same optical path.

[0070]

[0089] When the films of the present invention are said to have an optical path, it means that there is a path through which light can pass. Thus, when a layer is placed in the optical path, the layer is at least partially or significantly transparent. Any number of additional materials may be added to the optical path of the films of the present invention as long as they do not reduce the desired effect.

[0071]

[0090] The present invention therefore relates to infrared- or heat-reflective dielectric stacks or layers that act as filters. The basic embodiment of these filters is a multilayer interference filter directly bonded to a transparent support.

[0072]

[0091] In a preferred embodiment of the filter, the permeable layer may be deposited by physical vapour deposition (PVD), for example by sputter deposition, or by plasma enhanced chemical vapour deposition (PECVD), as previously described.

[0073]

[0092] The thicknesses of the various layers in the stack should be controlled to achieve an optimal balance between the desired infrared reflectance and the desired visible range emissive properties, and the ideal thickness may also depend on the nature of the transmissive dielectric used.

[0074]

[0093] Each of the transmissive layers may be, for example, from about 100 to about 200 nanometers (nm) thick, and the total thickness of the layers in the dielectric stack may be, for example, from about 700 to about 1300 nm.

[0075]

[0094] The transmissive layers may be of equal thickness, but this is not a requirement of the present invention. Similar optical thicknesses can be achieved when the thickness difference between one layer is about 5% to 15%, especially 10% thicker or thinner than the other layers.

[0076]

[0095] The layers can be deposited by evaporation, electron beam deposition, etc. Magnetron sputtering is the preferred deposition method, but any method capable of depositing, for example, a 100 nm layer with 10% accuracy can be used.

[0077]

[0096] The thickness selected will depend in part on the refractive index of the dielectric material used. High refractive index values ​​are typically at least 2, and low refractive index values ​​are typically less than about 1.5. In general terms, thicker layers may be required with lower refractive index materials, and thinner layers are used with higher refractive index materials.

[0078]

[0097] Examples of materials having a high refractive index include titanium oxide, niobium oxide, indium oxide, tantalum oxide, and zinc sulfide.

[0098] Examples of materials having a low refractive index include silicon oxide, magnesium fluoride, calcium fluoride, yttrium fluoride, and the like.

[0079]

[0099] Other typical inorganic dielectrics and their refractive indices are listed in sources such as Musikant, Optical Materials, Marcel Dekker, New York, 1985, pages 17-96, and may be used.

[0080]

[0100] The oxide dielectrics are conveniently deposited by reactive sputtering techniques, although, if desired, the dielectric layers can be applied using chemical vapor deposition and other physical or chemical vapor deposition techniques.

[0081]

[0101] According to this embodiment, each of the dielectric stacks is typically directly adhered to a transparent support. This support is several times thicker than the stack. This thick support can be important to the practical application of the invention. The stack itself is at most only a few hundred nanometers thick and therefore can only have minimal physical strength without the addition of a support. The support can be selected from among rigid and non-rigid, but minimally stretchable, transparent solids that can withstand the conditions of sputter deposition. Poly(esters), including poly(ethylene terephthalate) and other terephthalate ester polymers, poly(urethanes), cellulose ester polymers, acrylic polymers, and poly(vinyl fluorides), from about 1 or 2 mils to about 50 mils thick, are representative of non-rigid, minimally stretchable films that can be used. Poly(esters) and especially poly(ethylene terephthalate) are a preferred group of film supports.

[0082]

[0102] The stack may be adhered directly to the support, which can be done by sequentially applying the various layers of the stack directly to the support.

[0103] The macro-scale transparent layer, whether a plastic or glass transparent support or an additional component (e.g., a glass layer laminated to a plastic support film), contributes to the performance and visual optics of the final product, as shown in the examples.

[0083]

[0104] In some settings, the desired optical properties of the reflective stack include maximum rejection (reflection) of heat radiation (infrared wavelengths), with less attention paid to the amount of visible light transmitted or reflected. In other applications, a certain degree of visible light transmission must be obtained to satisfy government regulations. For example, in many areas, automobile windshields must have a Tvis of 70% or greater. Typically, at all wavelengths between 350 nm and 700 nm, the reflectance is less than 30%. This means that the reflectance is without any strong tint in the reflection that could be objected to. An ideal windshield would have 100% reflectance at wavelengths outside the visible range, achieving maximum rejection of heat.

[0084]

[0105] As previously mentioned, this aspect of the dielectric layer of the present invention allows for control of the color of reflectance from the filter. In many cases, this property can be used to obtain color neutrality. For colored light, this means colored reflection, and for white light, this means neutral reflection. This characteristic is described in the CIE L * a * b * 1976 color coordinate system, in particular the ASTM 308-85 method.

[0085]

[0106] L * a * b * When using the A standard light source, the characteristics are a near O * and b * Values ​​of a, for example, -4 to +1 * and b from -2 to +2 * As shown by:

[0086]

[0107] This neutral color can also be explained by the shape of the absorbance / reflectance versus wavelength curve.

[0108] In accordance with the present invention, one or both of the dielectric stacks may be polymer stacks, for example as disclosed in U.S. Patent No. 5,103,337, the relevant disclosure of which is incorporated herein by reference. In this embodiment, the dielectric stack may include an optical interference film made of multiple layers of polymers that are substantially transparent to wavelengths of light in the visible spectrum, but preferentially reflect wavelengths of light in the infrared region of the spectrum. Such optical interference films include multiple alternating layers of substantially transparent polymeric materials having different refractive indices.

[0087]

[0109] As described in U.S. Patent No. 5,103,337, such multilayer films are also described in Alfrey et al., U.S. Patent No. 3,711,176. When these polymers are selected to have a sufficient refractive index mismatch, the multilayer film produces constructive interference of light. This causes the film to transmit certain wavelengths of light through the film and reflect other wavelengths. Multilayer films can be made from relatively inexpensive, commercially available polymer resins that have the desired refractive index difference. The films have the added advantage that they can be molded or formed into other objects.

[0088]

[0110] As stated, the reflection and transmission spectrum for a particular film depends primarily on the optical thickness of the individual layers, where optical thickness is the product of the physical thickness of the layer and the refractive index. Films can be designed to reflect infrared, visible or ultraviolet wavelengths of light, depending on the optical thickness of the layers. When designed to reflect infrared wavelengths of light, such prior art films also exhibit high order reflections in the visible range, resulting in a pearlescent appearance for the film.

[0089]

[0111] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weights, reaction conditions, and the like used in the specification and claims are to be understood in all instances as being modified by the term "about". Thus, unless indicated to the contrary, the numerical parameters set forth in the following specification and the appended claims are approximations that may vary depending on the desired properties sought to be obtained by the present invention. At the very least, each numerical parameter should be construed in light of at least the number of reported significant digits and by applying ordinary rounding techniques. Moreover, the ranges set forth in this disclosure and claims are intended to specifically include the entire range, not just the endpoints. For example, a range stated as 0 to 10 is intended to disclose all integers between 0 and 10, such as 1, 2, 3, 4, etc., all decimals between 0 and 10, such as 1.5, 2.3, 4.57, 6.1113, etc., as well as the endpoints 0 and 10.

[0090]

[0112] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are intended to be precise reports given the methods of measurement. Any numerical values, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0091]

[0113] It should be understood that the reference to one or more process steps does not exclude the presence of additional process steps before or after the recited steps that are combined, or intervening process steps between those steps that are expressly identified. Furthermore, the naming of process steps, components or other aspects of information disclosed or claimed in this application using letters, numbers, or the like is a convenient means of identifying individual acts or components, and unless otherwise indicated, the recited description can be arranged in any order.

[0092]

[0114] As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. For example, n References to alcohol equivalents include multiple types of C n Alcohol equivalents are intended to be included. Thus, the use of phrases such as "at least one" or "at least some" in one place is not intended to imply the exclusion of plural reference from the use of "a," "an," and "the" elsewhere, unless the context clearly dictates otherwise. Similarly, the use of phrases such as "at least some" in one place is not intended to suggest that the absence of such phrases elsewhere is an indication that "all" is intended, unless the context clearly dictates otherwise.

[0093]

[0115] As used herein, the term "and / or," when used in a list of two or more items, means that any one of the listed items can be used alone, or any combination of two or more of the listed items can be used. For example, if a composition is described as containing components A, B, and / or C, the composition can contain only A, only B, only C, A and B in combination, A and C in combination, B and C in combination, or A, B, and C in combination.

[0094]

[0116] This invention may be further illustrated by the following examples of embodiments thereof, although it will be understood that unless otherwise specifically indicated, these examples are included for illustrative purposes only and are not intended to limit the scope of the invention. EXAMPLES

[0095] Example 1 Modeling Example

[0117] The thickness of the individual layers in both components or stacks can be adjusted to obtain certain colors or other optical values. Examples of stacks are shown in Figure 7 along with calculated performance values. The examples in Figure 7 are simulations of a 7-layer double peak and a 7-layer single peak stack.

[0096]

[0118] Another advantage is reduced manufacturing risk: with fewer optical layers for each stack component, the risk of error on the overall yield in the final build is significantly reduced. This allows longer campaigns to be manufactured, reducing the overall cost of production.

[0097]

[0119] The final construction can include infrared absorbers and other dyes to improve solar performance and / or adjust color if necessary. Due to very low or no dielectric absorption, the reflectors in this invention have very high visible light transmission. The high visible light transmission allows the addition of infrared absorbers, which significantly increases the total solar energy rejected (TSER) compared to metal-based products.

[0098]

[0120] Calculated performance parameters and a comparison with competitive products, as measured when applied on 3 mm glass, are shown in Table 1. Note from Table 1 that the present invention outperforms metallic NIR reflectors in some of the stacks described in this invention when used with certain high index contrast materials. Also note the high TSER values ​​that can be obtained from this design.

[0099] [Table 1] Example 2 Prototyping example

[0121] Due to the ongoing pandemic, resources and pilot machine availability were limited, so a proof of concept prototype was constructed using a small batch machine. The samples were constructed based on two sections: Section 1-single peak and Section 2-dual peak. Sections 1 and 2 were each constructed with five layers of quarter wave reflectors tuned in the near infrared. The design thicknesses for the two sections are given in Tables 2 and 3.

[0100] [Table 2]

[0101] [Table 3]

[0122] The batch machine does not have an in-situ thickness monitor, and the layer thickness was calculated by scaling deposition time. The deposition time provides a method to deposit a layer at a certain thickness, however, the thickness is not very accurate. For simplicity, two sections were constructed with five layers each. The resulting spectra of the sections have similar shape profiles as the design. The thickness error shifted similarly in both sections. This shift resulted in a shifted NIR reflector peak, but still successfully supported the concept of combining a single peak with a double peak.

[0102]

[0123] Table 4 and FIG. 8 are the graphs and target thicknesses, and a comparison of the design thicknesses versus the shifted thicknesses for section 1 is in Table 4.

[0103] [Table 4]

[0124] Figure 9 and Table 5 are graphs and a comparison of the target thickness and the design thickness versus the shifted thickness for section 2. The center of the double peak and the peak intensity balance shift due to the thickness shift from the process.

[0104] [Table 5]

[0125] FIG. 10 shows the effect of the engineered compound compared to the results from the prototype in each of the sections.

[0105]

[0126] The total reflectance of the compound design is shown in Figure 11. The design spectrum is compared to the prototype. Note that the overall broad shape of the reflector is very similar to the design, however the spectrum is shifted to the right due to a similar shift in both sections.

Claims

1. It is a solar control film, a. i. A first alternating layer of high-refractive-index material and low-refractive-index material of equal optical thickness, and ii. At least one layer that is an odd multiple of the first equal optical thickness A first dielectric stack having a reflection band centered on wavelengths of 800 nm to 1500 nm, b. A second dielectric stack optically adjacent to the first dielectric stack, i. A second alternating layer of high-refractive-index material and low-refractive-index material of equal optical thickness, and ii. At least one layer which is an even multiple of the second equal optical thickness, has at least the same width as the reflection band of the first dielectric reflective material stack, and produces a double-peak reflection band exhibiting both the first and second peaks in the wavelength range of 800 nm to 1500 nm. A second dielectric stack having Includes a sun-controlled film.

2. The sunlight control film according to claim 1, which reflects at least 30% of electromagnetic waves in the wavelength range of 850 nm to 1500 nm.

3. The sunlight control film according to claim 1, which reflects at least 30% of electromagnetic waves over a wavelength range of 600 nm.

4. c) The sunlight control film according to claim 1, further comprising a color correction layer including at least two alternating layers of high refractive index and low refractive index, each layer having an optical thickness of less than about one-eighth of a wavelength.

5. c) The sunlight control film according to claim 1, further comprising a color correction layer including at least two alternating layers of high refractive index and low refractive index, each layer having an optical thickness of less than about 1 / 16th of a wavelength.

6. The solar light control film according to claim 1, wherein the peak of the reflection band of the first dielectric stack lies between the first peak and the second peak of the reflection band of the second dielectric stack.

7. The sunlight control film according to claim 1, which transmits at least 90% of high-frequency wavelengths.

8. The solar control film according to claim 1, exhibiting at least 70% TVis.

9. The sunlight control film according to claim 1, wherein the odd multiple of the first equal optical thickness is a multiple selected from 1, 3, 5, 7, or 9.

10. The sunlight control film according to claim 1, wherein the even multiple of the second equal optical thickness is a multiple selected from 2, 4, 6, 8, or 10.

11. The sunlight control film according to claim 1, wherein at least one layer having an odd multiple of the first equal optical thickness is 1x the optical thickness.

12. The sunlight control film according to claim 1, wherein a single layer that is an even multiple of a second equal optical thickness is twice the equal optical thickness.

13. The sunlight control film according to claim 1, which reflects at least 50% of electromagnetic waves in the wavelength range of 800 nm to 1500 nm.

14. The solar control film according to claim 1, exhibiting at least 80% Tvis.

15. The sunlight control film according to claim 1, wherein a first dielectric reflective material stack and a second dielectric reflective material stack are deposited on the same substrate.

16. The solar control film according to claim 1, wherein a first dielectric reflective material stack and a second dielectric reflective material stack are deposited on separate substrates to form a solar control film.

17. The solar control film according to claim 1, wherein the first dielectric reflective material stack comprises 3 to 11 layers.

18. The sunlight control film according to claim 1, wherein the second dielectric reflective stack comprises 5 to 11 layers, and one of the three intermediate layers is a single layer having an even multiple of the second equal optical thickness.

19. The sunlight control film according to claim 1, wherein the broadband reflective film exhibits at least 20% sunlight reflection.

20. The solar control film according to claim 1, wherein a layer of high refractive index material has at least two refractive indices.

21. The solar control film according to claim 1, wherein the layer of low refractive index material has a refractive index of less than 1.

5.

22. The solar control film according to claim 1, wherein the layer of high refractive index material comprises one or more of titanium oxide, niobium oxide, indium oxide, tantalum oxide, zinc sulfide, and gallium nitride.

23. The sunlight control film according to claim 1, wherein the layer of low refractive index material comprises one or more of silicon dioxide, magnesium fluoride, or calcium fluoride.

24. The sunlight control film according to claim 1, which reflects at least 70% of electromagnetic waves in the infrared wavelength range of about 850 nm to about 1350 nm and at least 50% of electromagnetic waves in the infrared wavelength range of about 800 nm to about 1500 nm.

25. The solar light control film according to claim 1, wherein the repeating layers of high refractive index material and low refractive index material of the first dielectric reflective material stack are polymer layers.

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