Optical filters, films, and interlayers having a desired reflectance

Abstract

In aspects, the present invention relates to optical filters, films, and interlayers having a desired color reflectance. The present invention is also generally directed to optical filters having desired reflectance, and to products made from them, and to methods of using them.

Description

121365P511 PCOPTICAL FILTERS, FILMS, AND INTERLAYERS HAVING A DESIRED REFLECTANCEFIELD OF THE INVENTION

[0001] The present invention is generally directed to optical filters having desired reflectance, and to products made from them, and to methods of using them.BACKGROUND OF THE INVENTION

[0002] Recent years have seen a significant increase in the functionality provided by automotive glazing. While optical transparency, impact resistance, and durability remain key performance criteria, a host of new functionalities are being sought after by the consumer. These include sound damping, energy management, defroster capabilities, antenna I communications capabilities, sensor compatibility, and display capabilities.

[0003] One functionality particularly desirable in automotive windscreens is energy management.

[0004] U.S. Pat. No. 5,071 ,206 discloses visually transparent, color corrected, infrared reflecting films for solar heat control. The films employ Fabry-Perot sandwich interference filters, which are characterized by having three or more transparent layers of sputter-deposited metal, such as silver, directly contiguous with dielectric spacer layers and, optionally, boundary layers. Methods for producing these materials by sputtering techniques, as well as subsequent glazing methods for incorporating these films, are disclosed as well.

[0005] While there is a clear market demand for windshields, sidelites, and sunroofs with solar protection, this can lead to undesired color reflections. It is the intent of this invention to provide energy management functionality with a desired color reflectance.

[0006] Similarly, U.S. Pat. No. 6,416,872 discloses a heat reflecting transparent window cover having three layers. The composite has a substrate121365P511 PC and a unique heat reflective stack disposed upon the substrate. The heat reflective stack has, in series, a first interference layer, an infrared-reflecting metal layer, a second interference layer and a first non-infrared reflective layer. The first interference layer has an index of refraction which differs from the index of refraction of the substrate by at least about 0.1 . The first non-infrared reflective layer is composed of the material from one of the following groups of materials: (i) metals having an index of refraction greater than about 1 .0 and an extinction coefficient greater than about 2.0, and (ii) non-metals having an index of refraction greater than about 0.5 and an extinction coefficient greater than about 0.5.

[0007] As noted, solar control products can have an undesired reflectance color, especially when viewed at different angles. It is therefore desirable to reduce color variability when a solar products is viewed at different angles.SUMMARY OF THE INVENTION

[0008] In aspects, the present invention relates to optical filters, films, and interlayers having a desired color reflectance. The term “optical filter” may thus be used herein for convenience, but when a property of an optical filter is referred to, that property may be, depending on context, a property of the optical filter itself, that is a filter comprising a substrate and a multilayer stack. Alternatively, it may be a property of the optical filter in the form of a window film, for example a substrate provided with the multilayer stack on one side and a mounting adhesive on the other. Those skilled in the art will understand that such a film may also have additional layers, for example being laminated to one or more additional substrates. Likewise, the properties referred to herein may refer to the optical filter in the form of an interlayer, typically having one or more additional layers of a laminating material such as poly(vinyl butyral). Finally, the properties may refer to the properties of a glazing, that is, the interlayer having a glass substrate on each side. The context may determine which is being referred to, but in the absence of a specific reference, the properties referred to herein, such as VLT values and the like, may apply to the optical filter, a film or121365P511 PC interlayer comprising the optical filter, or a finished glazing incorporating the optical filter, optionally in the form of a film.

[0009] Further aspects of the invention are as disclosed and claimed herein.DETAILED DESCRIPTION

[0010] In one aspect, the optical filters, films, interlayers, and glazings according to the invention may selectively reflect infrared light, and will also typically reflect significant amounts of visible light, such that they may exhibit one or more of: a visible light reflection (VLR) value within the visible spectrum, as further described herein, of at least 8%, or at least 10%, or least 12%, or at least 15%, at least 20%, or at least 25%, or at least 30%, or at least 35%, or at least 40%, or at least 45%, or at least 50%, or at least 60% VLR, or as described elsewhere herein; and / or a total IRER %, as further described herein, of at least 70, or at least 72, or at least 75, or at least 78, or at least 80, or at least 82, or at least 85, or at least 90, or at least 95%, at least 97%, or as described elsewhere herein; and / or a total TTS value of no more than 10, or no more than 12, or no more than 15, or no more than 20, or no more than 25, or no more than 30, or as described elsewhere herein.

[0011] In aspects, metals and metal oxides are added in alternating layers of high and low refractive index, for example by sputtering, chemical vapor deposition, or the like. This may be referred to herein as an optical stack, and when reference is made to the alternating layers applied to a polymer substrate, will comprise the optical filter.

[0012] When we say that the optical filters may selectively reflect infrared light, we mean that it is designed to reflect wavelengths from the nominal red edge of the visible spectrum around 700nm and above, or from about 700 nm to about 2500nm, or from 700nm to 1200nm, that is, above the visible light spectrum. Reflective layers that selectively reflect in this wavelength range are understood to block heat, since the wavelengths that are reflected will not, for example, enter an automobile and heat up the interior. The IRER values, and121365P511 PC other values that implicate infrared light, are measured as further described below.

[0013] Thus, "visible radiation" or "visible light" means electromagnetic radiation having a wavelength of from about 380nm to about 750nm, or from about 400nm to about 700nm, while "Infrared radiation" or "heat" means electromagnetic radiation having a wavelength above about 700nm, or above about 750nm, or as described elsewhere herein. The values herein that implicate visible light, are measured as further described below.

[0014] "Transparent" means having the property of transmitting visible light, unless otherwise stated.

[0015] "VLT" or "Tvis" refer to a measure of transmittance over the visible wavelength, from 380nm to 780nm. It is an integrated term covering the area under the transmittance vs. wavelength curve throughout the visible wavelengths and weighted to the sensitivity of the human eye (CIE standard photopic observer, CIE 1931 2deg “y” function) and 1976 CIE D65 llluminant Standard.

[0016] "Transparent metal layers" are homogeneous coherent metallic layers composed, for example, of one or more of silver, gold, platinum, palladium, aluminum, copper, or nickel, and alloys thereof, of a thickness which permits substantial transparency.

[0017] "Sputter deposit" or "sputter-deposited" refers to the process or the product of the process in which a layer of material is laid down by the use, for example, of a magnetron sputterer.

[0018] "Dielectrics" as used herein, are nonmetallic materials which are typically transparent to both visible and infrared radiation. Generally, these materials are inorganic oxides but other materials such as organic polymers may be included as well. Thus, as used herein, the metal oxide layers are considered dielectric layers.

[0019] The term “dielectric” is used in this application in various contexts. The optical filters of the invention comprise a substrate having deposited thereon alternating layers of a metal layer and what we described as a121365P511 PC“dielectric spacer layer.” The “dielectric spacer layers” are themselves typically comprised of 2 or 3 layers of a dielectric material, which may be the same or different: a cap layer, a seed layer, and between the cap and seed layer a layer described as a “dielectric layer.” The entire “dielectric spacer layer” of the multilayer stack is thus typically comprised of a cap layer and a seed layer, with what is described as a “dielectric layer” placed between them.

[0020] "Contiguous" has its usual meaning of being in actual contact, i.e. of being adjoining. From time to time the somewhat redundant term "directly contiguous" is used for emphasis or clarification and has an identical meaning.

[0021] “Adjacent” means that the layers referred to are functionally related to one another. That is, layers are adjacent if, for example, light intended to pass through both layers indeed passes through both layers, with any layers lying between adjacent layers not blocking the intended function, in this case to pass light through the layers.

[0022] “Optically adjacent” thus means that the layers function together optically, that is, they are positioned in an optical path. The term “optically adjacent” thus allows for additional materials to be placed between optically adjacent layers, so long as they are in the same optical path.

[0023] When we say that the optical filters, films, interlayers, glazings, sunroofs or windshields of the invention have an optical path, we mean that there is a path that allows the light to pass through. Thus, if a layer is placed in the optical path, it will be to at least some or a significant extent transparent. Because the invention relates in part to minimizing unwanted reflections, any number of additional materials may be added to the optical paths of the systems of the invention so long as they do not detract from the desired effect.VLR

[0024] According to the invention, the optical filters may exhibit a visible light reflection (VLR) value within the visible spectrum of at least 8%, or at least 10%, or at least 12%, or at least 15%, at least 20%, or at least 25%, or at least 30%, or at least 35%, or at least 40%, or at least 45%, or at least 50%, or as described121365P511 PC elsewhere herein. Thus, the range of VLR% may range from about 8% to about 70%, or from 10% to 65%, or from 10% to 60%, or as described elsewhere herein. It will be understood by those skilled in the art that materials having a lower visual transmission value, that is a VLT% below 70% (which is below the transmission value required for windshields in many countries), may and typically does result in higher VLR values. As VLR values increase, the tendency to obtain undesired color changes at various viewing angles likewise increases. It is therefore an object of the invention, in certain aspects, to obtain a higher VLR value, and thus better solar performance, while avoiding undesired color changes.

[0025] The values provided herein, unless indicated otherwise, are normal incident values, that is, are measured at an incident angle of 0° with respect to the layer normal, that is, perpendicular to the surface. Because the reflected color at various angles is an aspect of the invention, many of the values herein are measured at angles other than 0°, and are indicated as such. As further elaborated upon, these angles may include 15°, 30°, 45°, 60°, 75°, and 85°.

[0026] “VLR” or “Rvis” refer to a measure of reflectance over the visible wavelength, from 380nm to 780nm. It is an integrated term covering the area under the reflectance vs. wavelength curve throughout the visible wavelengths and weighted to the sensitivity of the human eye (CIE standard photopic observer, CIE 1931 2deg “y” function)and 1976 CIE D65 llluminant Standard.TTS value

[0027] According to the invention, the optical filters may exhibit a total TTS% value of no more than 12, or no more than 15, or no more than 16, or no more than 20, or no more than 25, or no more than 28, or no more than 30, or no more than 45%.

[0028] According to the invention, the “TTS” is the total solar transmission; is calculated as 1 -TSER (total solar energy rejected). The TSER is the calculated solar reflection in addition to the fraction of solar absorption that is not re-irradiated into the interior, TSER=Rsol+0.692Asol; 0.692 is assumed the121365P511 PC fraction of solar energy absorbed that is removed as external radiation, and airflow over the outside of the vehicle. The “Rsol” solar reflection and “Tsoi” solar transmission are calculated from the spectra from 300nm to 2500nm as a normalized weighted average thru the glazing; the weight function is the solar energy spectra according to ASTM E-891 AM 1 .5. The “Asol” solar absorption is calculated as 1 -Tsol-Rsol. The TSER is calculated according to the National Fenestration Rating Council NFRC-300 test method for determining the solar optical properties of glazings.VLT values

[0029] As noted, "VLT" refers to a measure of transmittance over the visible wavelength, from 380nm to 780nm, and is expressed as a percent. It is an integrated term covering the area under the transmittance vs. wavelength curve throughout the visible wavelengths and weighted to the sensitivity of the human eye and 1976 CIE D65 llluminant Standard.

[0030] According to the invention, the VLT values of the optical filters, window films, interlayers, and glazings of the invention may vary widely, depending on intended use. For example, many jurisdictions require that windshields have a VLT of at least 70%, while a few jurisdictions may require slightly less.

[0031] When a sunroof or the like may be intended, or other low-VLT application, the VLT value may be relatively low, for example, such as from about 2% to about 60%, or from 5% to 50%, or from 8% to about or at least 2, 3, 5, 7, 9, 10, 12, 15, 18, 20, 25, 28, 32, 33, 34, 35, 36, 37, 38, 39, or 40%, up to 50, 55, 58, 60, 65, 68, or 70% or more.

[0032] . When a windshield or other high-VLT application may be intended, the VLT value may be relatively high, for example, such as from about 50% to about 85%, or from 60% to 82%, or from 70% to 80%, for example, or at least 50, at least 52, 53, 55, 57, 59, 60, 62, 65, 66, 67, 68, 69, or at least 70%, 71 , 72, 73, 74, 75, 76, 77, 79, or at least 80%, up to 88, 87, 86, 85, 84, 83, 82, 81 , or up to 80%, 79, 78, 77, 76, or up to 75%.121365P511 PC

[0033] In other aspects, the optical layers of the invention may exhibit a VLT / TTS value of, for example, from about 0.5 to about 2.5, or from 0.7 to 2.3, or from 1 to 2.0, or at least 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 , 1.2, 1.3, 1.4, or at least 1.5, up to about 2.5, 2.4, 2.3, 2.2, 2.1 , 2.0, 1.9, 1.8, 1.7, 1.6, 1.5, or 1.4, for example.

[0034] In other aspects, the optical layers of the invention may, when they exhibit a VLT of no more than 60%, exhibit an IRER / VLR value from about 1 to about 6, or from 1 .2 to 5, or from 1 .5 to 4.5, or at least 1 , 1.1 , 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.8, or 2,0, up to about 4, 4.1 , 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.1 , 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, or up to 6, for example.

[0035] In other aspects, the optical layers of the invention may, when they exhibit a VLT of at least 60%, exhibit an IRER / VLR value from about 6 to about 10, or from 6.5 to 9, or from 7 to 8, or at least 6, 6.1 , 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, or 7.0, up to 7.1 , 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1 , 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, or up to 9, for example.

[0036] In other aspects, the optical layers of the invention may, when they exhibit a VLT of no more than 60%, exhibit an IRER x VLR from about 1000 to about 6000, or from 1100 to 5800, or from 1200 to 5500, or at least 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000, 3100, 3200, 3300, 3400, 3500, up to about 4000, 4100, 4200, 4300, 4400, 4500, 4600, 4700, 4800, 4900, 5000, 5500, or up to 6000, for example.

[0037] In other aspects, the optical layers of the invention may, when they exhibit a VLT of at least 60%, exhibit an IRER x VLR from about 700 to about 2000, or from 800 to 1800, or from 900 to 1700, or at least 700, or at least 800, 900, 1000, 1100, or at least 1200, up to 1700, 1800, 1900, or 2000, for example.IRER value

[0038] According to the invention, the optical filters may exhibit a total IRER value, a total IRER %, as further described herein, of at least 70, or at least 72, or at least 75, or at least 78, or at least 80, or at least 82, or at least 85, or at121365P511 PC least 90, or at least 95%, or at least 97%, or as described elsewhere herein. According to the invention, “IRER” (infrared energy rejection) values represent the TSER (total solar energy rejection) value based only on the NIR region of the spectrum (780-2500nm). It accounts for any heat effect caused by absorption and re-radiation.L* a* b*

[0039] According to the invention, the optical filters may exhibit a relatively consistent reflective color at varying viewing angles, characterized by one or more of : an a* at 30°, 45°, 60°, and 75° that is from about -10 to about 10, or from -10 to 0, or from -8 to 0, or from -7 to -1 , or as described elsewhere. They may likewise exhibit a maximum difference in a* values at 30°, 45°, 60°, and 75° that is no higher than 10 units, or no higher than 9, or no higher than 8, or no higher than 7, or no higher than 6, or no higher than 5, or no higher than 4, 3, 2 units, or even 1 unit; or from 0 to 5 units. In some aspects, the maximum difference in a* values at 30°, 45°, 60°, and 75° may be less than 0.9, 0.8, 0.7, or 0.5 units.

[0040] In another aspect, the optical filters may exhibit an a* value at 30°, 45°, and 60° that is lower than the a* value at 0°.

[0041] In other aspects, an a* at 30° and 75° is higher than an a* value at 45° and 60°.

[0042] In another aspect, the difference between the a* value at 0° and the a* value at 75° is no greater than 8 units, or no greater than 5 units, or no greater than 3 units.

[0043] In another aspect, the a* value at 45° is lower than the a* value at 0° 30°, 60°, and 75°.

[0044] In yet another aspect, the difference between the a* value at 45° and the highest measured a* value at 0°, 30°, 60°, and 75° is no greater than 5 units, or no greater than 10 units.

[0045] Likewise, the optical filters of the invention may have b* values at 30°, 45°, 60°, and 75° that are from about -10 to about 20, or from -9 to 15, or121365P511 PC from -8 to 12, or from -7 to 10, or as described elsewhere. Likewise, the optical filters of the invention may have a maximum difference in b* values at 30°, 45°, 60°, and 75° that is no higher than 15 units, or no higher than 12, or no higher than 10, or no higher than 8, or no higher than 7, or 6, or 5, or 4, or 2 units or even 1 unit. In some aspects, the maximum difference in b* values at 30°, 45°, 60°, and 75° may be less than 0.9, 0.8, 0.7, 0.6, or 0.5 units.

[0046] In another aspect, the optical filters may exhibit an b* value at 30°, 45°, and 60° that is greater than the b* value at 0°.

[0047] In other aspects, an b* at 30° and 75° is less than an b* value at 45° and 60°.

[0048] In another aspect, the difference between the b* value at 0° and the b* value at 75° is no greater than 8 units, or no greater than 5 units, or no greater than 3 units.

[0049] In another aspect, the b* value at 45° is greater than the b* value at 0° 30°, 60°, and 75°.

[0050] In yet another aspect, the difference between the b* value at 45° and the highest measured b* value at 0°, 30°, 60°, and 75° is no greater than 5 units, or no greater than 10 units.

[0051] According to the invention, the optical filter permits one to control the color of reflectance of the filter. In some cases the property is used to attain color neutrality. With colored light this means a colored reflection or with white light a neutral reflection. This feature can be quantitated by the CIE L*a*b* 1976 color coordinate system, in particular the ASTM 308-85 method, as further described herein.

[0052] In some aspects, the property is used to attain color uniformity at different angles of incidence, that is, at different viewing angles. With colored light this means a colored reflection or with white light a neutral reflection. This feature likewise can be quantitated by the CIE L*a*b* 1976 color coordinate system, in particular the ASTM 308-85 method, as further described herein.

[0053] Using the L*a*b* system the property is shown by values for a* and b* near 0 for example a* from -4 to +1 and b* from -2 to +2 when using an121365P511 PC llluminant D65 light source. FIG. 14 is a L*a*b* color coordinate chart which shows the desired color coordinates and defines the desired color space. Reflected color coordinates L*a*b* are calculated from the reflection spectra from 380nm to 780nm. To calculate L*a*b* coordinates, the tristimulus X, Y , and Z coordinates needs to be calculated first. The tristimulus values X Y, and Z represent the intensity of the primary color values and are calculated as weighted averages from the spectra where the weight function mimics how the human eye sees as defined in CIE 1976 10 degrees standard observer. The coordinates L*a*b* are then calculated from XYZ according to CIELAB-1976 color space standards with a white reference of D65 dE, dC

[0054] According to the invention, the optical filters may exhibit a AE of no more than 25, for example; or a AC* of no more than 15, for example, when comparing the reflective L*a*b* color coordinates measured at a chosen first angle of 0°, 30°, or 45° to the reflective L*a*b* color coordinates measured at a chosen second angle of 0°, 30°, 45°, 60° or 75°. That is, AE or AC* values are determined with respect to 0° and 30°, 0° and 45°, 0° and 60°, and 0° and 75°; AE or AC* values are determined between 30° and 0°, 30° and 45°, 30° and 60° and 30° and 75°, and AE or AC* values are determined between 45° and 0°, 45° and 30°, 45° and 60°, and 45° and 75°, and in all of the 12 values calculated for each, none of the values are greater than the maximum AE or AC* values, as the case may be, as defined herein.

[0055] In other aspects, the optical filters may exhibit a DE of no more than 25, for example, or no more than 20, or no more than 15, or no more than 12, or no more than 10, or no more than 9, or no more than 8, or no more than 7, or no more than 6, or no more than 5, or no more than 4, or no more than 3, or no more than 2, or no more than 1 , or no more than 0.5.

[0056] In further aspects, the optical filters may exhibit a DC* of no more than 15, for example, or no more than 14, or no more than 13, or no more than 12, or no more than 11 , or no more than 10, or no more than 9, or no more121365P511 PC than 8, or no more than 7, or no more than 6, or no more than 5, or no more than 4, or no more than 3, or no more than 2, or no more than 1 , or no more than 0.5.

[0057] According to the invention, DE may be calculated as the magnitude of the vector between the reflective color coordinate values at two different angles, as just described, (L*1 , a*i, b*i) and (L*2, a*2, b*2), in the L*a*b* color coordinate system, according to Equation 1.Equation 1. AE = lAL*2+ Aa*2+ Ab*2where AL* = L*x- L2Aa* = Qj - a2Ab* = b - b2*

[0058] According to the invention, AC* may be calculated as the chroma difference between the reflective color coordinate values at two different angles, as just described, (L*i, a*i, b*i) and (L*2, a*2, b*2), in the reflective L*a*b* color coordinate system, according to Equation 2.Equation 2.

[0059] In preferred embodiments of this filter, the transparent metal layers may be sputter-deposited. In addition, layers referred to may be directly contiguous with the transparent metal layers. Nucleation layers may not be required when the transparent metal layers are sputter-deposited, although nucleation layers may be present if desired.Metal layers

[0060] As noted, the optical filters of the invention are provided with one or more metal layers.

[0061] In one aspect, two, three, four, or more than four transparent metal layers, each typically separated from one another by at least a mixed oxide layer, can be employed. In theory, there is no limit to the number of transparent metal layers that can be used in these sandwich filters. In practice, however121365P511 PC three to five transparent metal layers may be preferred, with three or four transparent metal layers typically being quite suitable.

[0062] The metal layers can be deposited by vapor deposition methods, electron-beam deposition, magnetron sputtering methods, and the like.

[0063] Each of the transparent metal layers may be, for example, at least 3 nm, or at least 4 nm, or at least 5, 6, 7, 8, 9, or 10nm, or from about 4 to about 40 nanometers (nm) in thickness, or from 5 to 38 nm, or from 8 to 30 nm, or from 10 to 30 nm, or from 12nm to 20nm, or up to 20nm, or up to 25nm, 26nm, 27nm, 28nm, or up to 30nm or up to 32 nm, or up to 35nm, or up to 38nm, or as described elsewhere herein.

[0064] The total thickness of metal in the optical filter may be, for example, at least 20nm, or at least 25 nm, or at least 28, 29, 30, 31 , 32, 33, 34, 35, 36, 37, 38, 29, or 30nm, 31 , 32, 33, 34, 35, 36, 37, 38, 39nm, 40nm, 41 , 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 , 52, 53, 54, 55, 56, 57, 58, 59, or 60nm. The total thickness of metal in the optical filter may be, for example, up to about 80nm, 79nm, 78, 77, 76, 75, 74, 73, 72, 71 , 70, 69, 68, 67, 66, 65, 64, 63, 62, or 61 nm.

[0065] The total thickness of metal in the optical filter may be, for example in cases where the VLT is greater than about 60%, from about 15 to about 75 nm, or from 20 to 70, or from 25 to 65 nm, or from 30 to 60nm, or from 35 to 55nm.

[0066] When the number of metal layers is four and the VLT is greater than about 60%, the total thickness of metal in the optical filter may be, for example, from about 15 to about 75 nm, or from 30 to 70nm, or from 35 to 65 nm, or from 40 to 60nm, or from 45 to 65nm.

[0067] The total thickness of metal in the optical filter may be, for example in cases where the VLT is less than about 60%, from about 30 to about 80 nm, or from 35 to 75nm, or from 38 to 70 nm, or at least 35, 36, 37, 38, 39, 40, 41 , 42, 43, 44, 45, 46, 47, 48, 49, or 50nm, or up to 80nm, or up to 79, up to 78, 76, 75, 74, 73, 72, 71 , 70, 69, 68, 67, 66, 65, 64, 63, 62, or 61 nm.

[0068] With silver and silver alloyed with up to about 25% wt of gold, which constitute preferred transparent metals, excellent results are obtained with121365P511 PC three or four layers of metal, each from 4 to 35 nm in thickness or from about 5 to about 30 nm. The amount of gold in a silver alloy may thus be at least 2%, or at least 3%, or at least 5%, or at least 8% by weight. The amount may be from about 1 % to about 20%, or from 2% to 15%, or from 2% to 8%, or from 3% to 7% gold by weight. We have found that using gold in silver alloys can assist in reducing metal corrosion.

[0069] Although the three transparent metal layers may be of equal thickness, this is not a requirement of the present invention. Satisfactory results have been achieved when the middle of three metal layers is thicker than each of the outer layers.Dielectric spacer layers

[0070] In an aspect, the optical filters of the invention may be provided with dielectric spacer layers typically comprising one or more metal oxide layers. The dielectric spacer layers of the invention typically comprise a seed layer, a dielectric layer, and a cap layer. A cap layer is used when the underlying layer on which the dielectric spacer layer is deposited is a metal layer, after which the dielectric layer is deposited on the cap layer. After the dielectric layer is deposited, a seed layer, also typically consisting of a dielectric material, is deposited in order to promote a uniform crystalline structure to the metal layer being deposited on it.

[0071] The dielectric spacer layers useful according to the invention are provided in layers, which may be the same or different, and may each be, for example, a total thickness (cap, dielectric, and seed layers when present) from about 20 to about 200 nm in thickness, or from about 20 nm to about 150 nm, or from 25nm to 130nm, or from 30nm to 120nm, or from 32nm to 115nm, or at least 20, 22, 25, 28, 30, 32, or 35, and up to 115, 120, 130, 132, 150, or 200nm

[0072] Of the total thickness of the dielectric spacer layers, the thickness of the dielectric layer, which may be the “middle layer” of the dielectric spacer layer, may be, for example, from about 5nm to about 150, or 7nm to 125, or121365P511 PC from 10nm to 115nm, or at least 3, 5, 6, 7, 8, 10, 12, or 15nm, up to 150nm or up to 145, 140, 135, 130, 125, 120, or 115nm.

[0073] Of the total thickness of the dielectric spacer layers, the thickness of the cap layer, may be, for example, from about 3nm to about 10nm, or from 4nm to 8nm, or from 5 to 7nm, or at least 2, 3, 4, 5, or 6nm, up to 6, 7, 8, 9, 10, or 12nm.

[0074] Of the total thickness of the dielectric spacer layers, the thickness of the seed layer, if present, may be, for example, from about 5 to about 25nm, or from 7 to 20nm, or from 10 to 20nm, or at least 5, 6, 7, 8, 9, 10, 11 , or 12nm, up to 18, 20, 21 , 22, 23, 25, or 28nm.

[0075] As further described herein, the thicknesses of the dielectric spacer layers selected may depend upon the index of refraction of the dielectric employed. Index of refraction values can be from about 1 .4 to 2.7, or from 2.0 to 2.3, or from 1.9 to 2.1 , for example. In a general relationship, thicker layers may be called for with lower index material while thinner layers may be used with higher index material.

[0076] Suitable metal oxide materials include the inorganic dielectrics such as metallic and semimetallic oxides, for example zinc oxides, especially zinc aluminum oxide, indium oxides, tin oxides, titanium oxides, silicon oxides, silicon oxides, bismuth oxides, chromium oxide, niobium oxides, as well as other inorganic metal compounds and salts, for example zinc sulfides and magnesium fluorides, and mixtures thereof. Of these materials, preference may be given to niobium oxides, zinc oxide, indium oxide, tin oxide, and mixtures thereof and titanium dioxide. Other suitable materials include hydrocarbon and oxyhydrocarbon organic polymers (1.55-1.65 index of refraction) and fluorocarbon polymers (1.35-1.45 index of refraction). Other suitable materials include lead oxide, aluminum fluoride, bismuth oxide and zinc sulfide.

[0077] As described herein, the inorganic, metallic, and semimetallic oxide dielectrics can be conveniently and preferably deposited by sputtering techniques, although, if desired, chemical vapor deposit and other physical vapor deposition methods can be employed to apply the dielectric layers.121365P511 PC

[0078] The cap and seed layers of the dielectric spacer layers may be considered “boundary layers.” It may be preferred to have a symmetric sandwich with boundary layers on both outside surfaces. However, if desired, one or both of the boundary layers can be omitted. The boundary layers can be the same or different dielectrics and can be identical to or different than the dielectric portion of the dielectric spacer layer. The same preferences for materials recited for the dielectric layer apply to the boundary layers and, for simplicity, the boundary layers and the dielectric layer may all be made of the same materials, or they may all be different.

[0079] According to the invention, the thicknesses of the various layers in the filter should be controlled to achieve an optimum balance between desired reflectance and transmittance. The ideal thicknesses can also depend upon the nature of the transparent metal and dielectric employed.Substrates

[0080] According to the invention, the optical filters typically comprise a substrate, and the alternating layers of a dielectric spacer layer and a metal layer, as described, may be deposited on the substrate. The substrate is not particularly limited, but will typically be a polymer such as polyethylene terphthalate) or other terphthalate ester polymers, but may also comprise poly(urethanes), cellulose ester polymers, acrylic polymers, and poly(vinyl fluoride)s, with typical thicknesses of PET used being from about 1 or 2 mils to about 10 mils in thickness. Poly(esters) and in particular poly(ethylene terphthalates) are a preferred group of film supports.Interlayers

[0081] In aspects of the invention, the optical filters of the invention just described are used to form interlayers of the invention. These interlayers include the optical filters just described, typically comprising a substrate and a multilayer stack deposited thereon, and at least one additional layer of an adhesive or interlayer material such as poly(vinyl butyral). Typically, after a121365P511 PC layer of PVB is contacted with the optical filter to form a two-layer interlayer, it is afterward contacted with an additional PVB layer, which may be a flat or wedge-shaped PVB layer, and then combined with glass substrates to form a glazing.

[0082] Thus, in an aspect, the invention provides a composite laminate interlayer comprising the optical filters of the invention between layers of plasticized PVB adhesive.

[0083] In one aspect, the present invention is thus directed to a bilayer interlayer that is useful as a solar control interlayer. This interlayer may in turn be useful as an interlayer for a laminated composite wherein the interlayer is sandwiched between two rigid sheets, such as glass, to form a glass laminate. This bilayer may thus include a first layer and a second layer, with the first layer being the optical filter already described. A second PVB layer is typically used, on the side opposite the first PVB layer, and then the first and second PVB layers are contacted with a first and a second glass layer, respectively, to form a glass laminate.

[0084] Due to the electrical-conduction properties of the optical filters of the invention provided by the metal layers, the optical filters may, when incorporated into a glass laminate, provide the desired solar-rejection properties with a desired reflectance, as well as providing additional functionalities.

[0085] For example, the optical filters may also serve as heating elements, upon application of suitable electrodes which are located so as to cause a flow of current through the optical filter. This “heating element” comprised of the optical filter may thereby assist in de-icing and de-fogging the glass laminate.

[0086] Further, the optical filter of the invention may likewise serve as a transparent multiband. See, for example, U.S. Pat. No. 8,704,719 related to a multi-function antenna, the relevant portion of which is incorporate herein by reference.

[0087] The two-layer interlayer just described, comprising the optical filters of the invention combined with a PVB layer, may be produced and sold, as121365P511 PC such, and cut to the desired shape of a windshield during use, for example using a kiss-cut. When afterward combined with a second PVB layer as just described, which may be a wedge layer, the resulting interlayer may thus provide a multi-functional windshield which may simultaneously provide a head- up display, a heating element, and a transparent antenna, while also providing desirable solar control properties and a desired reflectance, all with a product that is more economical than coated glass solutions. As set out below, the interlayers used herein may further contain acoustic functionality, color functionality, and gradient color band functionality.

[0088] We note further that the kiss-cut just described may also advantageously include a cutout for use, for example, with a LIDAR camera or other sensor. With selection of a suitable ultra-clear glass such as a Pilkington Optiwhite product or a suitable AGC Dragontail product, a windshield may be produced with improved transmittance in the LIDAR range, another advantage that is difficult to achieve with coated glass solutions.

[0089] With respect to the interlayer aspects of the invention, the terms “polymer interlayer,” “interlayer,” “polymer layer,” “layer” and “sheet” as used herein with respect to the interlayers of the inventon, may designate a singlelayer sheet of PVB adjacent the optical filter of the invention, or a multilayered PVB assembly. A “single-layer sheet,” as the name implies, is a single polymer layer extruded as one layer. A “bilayer” interlayer designates at least two but optionally more than two layers, including separately extruded layers, coextruded layers, or any combination of separately and co-extruded layers. A multilayered assembly may comprise multiple layers, including separately extruded layers, co-extruded layers, or any combination of separately and coextruded layers. Typically, the interlayers of the invention will have one or more separately-extruded PVB layers that are then combined with the optical filters of the invention, as already described,

[0090] By way of non-limiting example, a multilayered interlayer could comprise, for example: two or more single-layer sheets combined together (“plural-layer sheet”); two or more layers co-extruded together (“co-extruded121365P511 PC sheet”); two or more co-extruded sheets combined together; a combination of at least one single-layer sheet and at least one co-extruded sheet; and a combination of at least one plural-layer sheet and at least one co-extruded sheet. In various embodiments of the present invention, a multilayered interlayer comprises at least two polymer layers (e.g., a single layer or multiple layers co-extruded) disposed in contact with each other, wherein each layer comprises a polymer resin.

[0091] The term “resin,” as utilized herein with respect to the interlayer refers to the polymeric component, poly(vinyl acetal) and especially poly(vinyl butyral), referred to as PVB. Generally, the PVB is combined with plasticizer, such as those discussed more fully below, to result in a plasticized PVB. Additionally, and as exemplified herein, plasticized resin may have other components or ingredients in addition to the polymer or resin and plasticizer.

[0092] As used herein, the term “molecular weight” refers to weight average molecular weight (Mw). The molecular weight of the PVB resin can be in the range of from about 50,000 to about 600,000, about 70,000 to about 450,000, or about 100,000 to about 425,000 Daltons.

[0093] The PVB resin may be produced by known aqueous or solvent acetalization processes by reacting polyvinyl alcohol (“PVOH”) with butyraldehyde in the presence of an acid catalyst, separation, stabilization, and drying of the resin. Such acetalization processes are disclosed, for example, in U.S. Pat. Nos. 2,282,057 and 2,282,026 and Wade, B. (2016), “Vinyl Acetal Polymers”, Encyclopedia of Polymer Science and Technology, pp. 1 -22 (John Wiley & Sons, Inc.), the entire disclosures of which are incorporated herein by reference.

[0094] While generally referred herein as “poly(vinyl acetal)” or “poly(vinyl butyral),” the resins described herein may include residues of any suitable aldehyde, including, but not limited to, isobutyraldehyde. In some embodiments, one or more poly(vinyl acetal) resin can include residues of at least one Ci to C10 aldehyde, or at least one C4 to Cs aldehyde. Examples of suitable C4 to Cs aldehydes can include, but are not limited to, n-butyraldehyde,121365P511 PC isobutyraldehyde, 2-methylvaleraldehyde, n-hexyl aldehyde, 2-ethylhexyl aldehyde, n-octyl aldehyde, and combinations thereof.

[0095] In many embodiments, plasticizers are added to the polymer resin to form polymer layers or interlayers. Plasticizers are generally added to the polymer resin to increase the flexibility and durability of the resultant polymer interlayer. Plasticizers function by embedding themselves between chains of polymers, spacing them apart (increasing the “free volume”) and thus significantly lowering the glass transition temperature (Tg) of the polymer resin, making the material softer. In this regard, the amount of plasticizer in the interlayer can be adjusted to affect the glass transition temperature (Tg), the temperature that marks the transition from the glassy state of the interlayer to the rubbery state. In general, higher amounts of plasticizer loading can result in lower Tg. In some embodiments, such as when the interlayer is an acoustic trilayer, the inner core layer (i.e., the soft layer) will have a glass transition temperature less than about 20°C, while the outer skin layers (e.g., the stiff layer) will have a glass transition temperature greater than about 25°C.

[0096] Contemplated plasticizers include, but are not limited to, esters of a polybasic acid, a polyhydric alcohol, triethylene glycol di-(2-ethylbutyrate), triethylene glycol di-(2-ethylhexonate) (known as “3-GEH”), triethylene glycol diheptanoate, tetraethylene glycol diheptanoate, dihexyl adipate, dioctyl adipate, hexyl cyclohexyladipate, mixtures of heptyl and nonyl adipates, diisononyl adipate, heptylnonyl adipate, dibutyl sebacate, and polymeric plasticizers such as oil-modified sebacic alkyds and mixtures of phosphates and adipates, and mixtures and combinations thereof. 3-GEH is particularly preferred. Other examples of suitable plasticizers can include, but are not limited to, tetraethylene glycol di-(2-ethylhexanoate) (“4-GEH”), di(butoxyethyl) adipate, and bis(2-(2-butoxyethoxy)ethyl) adipate, dioctyl sebacate, nonylphenyl tetraethylene glycol, and mixtures thereof.

[0097] Other suitable plasticizers may include blends of two or more distinct plasticizers, including but not limited to those plasticizers described above. Still other suitable plasticizers, or blends of plasticizers, may be formed from121365P511 PC aromatic groups, such polyadipates, epoxides, phthalates, terephthalates, benzoates, toluates, mellitates and other specialty plasticizers. Further examples include, but are not limited to, dipropylene glycol dibenzoate, tripropylene glycol dibenzoate, polypropylene glycol dibenzoate, isodecyl benzoate, 2-ethylhexyl benzoate, diethylene glycol benzoate, propylene glycol dibenzoate, 2,2,4-trimethyl-1 ,3-pentanediol dibenzoate, 2,2,4-trimethyl-1 ,3- pentanediol benzoate isobutyrate, 1 ,3-butanediol dibenzoate, diethylene glycol di-o-toluate, triethylene glycol di-o-toluate, dipropylene glycol di-o-toluate, 1 ,2- octyl dibenzoate, tri-2-ethylhexyl trimellitate, di-2-ethylhexyl terephthalate, bisphenol A bis(2-ethylhexaonate), ethoxylated nonylphenol, and mixtures thereof. In some embodiments, the plasticizer can be selected from the group consisting of dipropylene glycol dibenzoates, tripropylene glycol dibenzoates, and combinations thereof.

[0098] Generally, the plasticizer content of the polymer interlayers of this application are measured in parts per hundred resin parts (“phr”), on a weight per weight basis. For example, if 30 grams of plasticizer is added to 100 grams of polymer resin, the plasticizer content of the resulting plasticized polymer would be 30 phr. When the plasticizer content of a polymer layer is given in this application, the plasticizer content of the particular layer is determined in reference to the phr of the plasticizer in the melt that was used to produce that particular layer. In some embodiments, the high rigidity interlayer comprises a layer having a plasticizer content of less than about 35 phr and less than about 30 phr.

[0099] According to some embodiments of the present invention, one or more polymer layers described herein can have a total plasticizer content of at least about 20 phr, at least about 25 phr, at least about 30 phr, at least about 35 phr, at least about 38 phr, at least about 40 phr, at least about 45 phr, at least about 50 phr, at least about 55 phr, at least about 60 phr, at least about 65 phr, at least about 67 phr, at least about 70 phr, at least about 75 phr of one or more plasticizers. In some embodiments, the polymer layer may also include not more than about 100 phr, not more than about 85 phr, not more than 80121365P511 PC phr, not more than about 75 phr, not more than about 70 phr, not more than about 65 phr, not more than about 60 phr, not more than about 55 phr, not more than about 50 phr, not more than about 45 phr, not more than about 40 phr, not more than about 38 phr, not more than about 35 phr, or not more than about 30 phr of one or more plasticizers. In some embodiments, the total plasticizer content of at least one polymer layer can be in the range of from about 20 to about 40 phr, about 20 to about 38 phr, or about 25 to about 35 phr. In other embodiments, the total plasticizer content of at least one polymer layer can be in the range of from about 38 to about 90 phr, about 40 to about 85 phr, or about 50 to 70 phr.

[0100] When the interlayer includes a multiple layer interlayer, two or more polymer layers within the interlayer may have substantially the same plasticizer content and / or at least one of the polymer layers may have a plasticizer content different from one or more of the other polymer layers. When the interlayer includes two or more polymer layers having different plasticizer contents, the two layers may be adjacent to one another. In some embodiments, the difference in plasticizer content between adjacent polymer layers can be at least about 1 , at least about 2, at least about 5, at least about 7, at least about 10, at least about 20, at least about 30, at least about 35 phr and / or not more than about 80, not more than about 55, not more than about 50, or not more than about 45 phr, or in the range of from about 1 to about 60 phr, about 10 to about 50 phr, or about 30 to 45 phr. When three or more layers are present in the interlayer, at least two of the polymer layers of the interlayer may have similar plasticizer contents falling for example, within 10, within 5, within 2, or within 1 phr of each other, while at least two of the polymer layers may have plasticizer contents differing from one another according to the above ranges.

[0101] In some embodiments, one or more polymer layers or interlayers described herein may include a blend of two or more plasticizers including, for example, two or more of the plasticizers listed above. When the polymer layer includes two or more plasticizers, the total plasticizer content of the polymer layer and the difference in total plasticizer content between adjacent polymer121365P511 PC layers may fall within one or more of the ranges above. When the interlayer is a multiple layer interlayer, one or more than one of the polymer layers may include two or more plasticizers. In some embodiments when the interlayer is a multiple layer interlayer, at least one of the polymer layers including a blend of plasticizers may have a glass transition temperature higher than that of conventional plasticized polymer layer. This may provide, in some cases, additional stiffness to layer which can be used, for example, as an outer “skin” layer in a multiple layer interlayer.

[0102] In addition to plasticizers, it is also contemplated that adhesion control agents (“ACAs”) can also be added to the polymer resins to form polymer interlayers. ACAs generally function to alter and / or improve the adhesion of the interlayer to the glass panels when forming a laminated panel. Contemplated ACAs include, but are not limited to, magnesium carboxylates / salts. In addition, contemplated ACAs may also include those ACAs disclosed in U.S. Patent 5,728,472, incorporated by reference herein in its entirety, such as residual sodium acetate, potassium acetate, and / or magnesium bis(2-ethyl butyrate).

[0103] Other additives may be incorporated into the interlayer to enhance its performance in a final product and impart certain additional properties to the interlayer. Such additives include, but are not limited to, dyes, pigments, stabilizers (e.g., ultraviolet stabilizers), antioxidants, anti-blocking agents, flame retardants, IR absorbers or blockers (e.g., indium tin oxide, antimony tin oxide, lanthanum hexaboride (LaBe) and cesium tungsten oxide), processing aides, flow enhancing additives, lubricants, impact modifiers, nucleating agents, thermal stabilizers, UV absorbers, UV stabilizers, dispersants, surfactants, chelating agents, coupling agents, adhesives, primers, reinforcement additives, and fillers, among other additives known to those of ordinary skill in the art.

[0104] One parameter used to describe the polymer resin components of the polymer interlayers of this application is residual hydroxyl content (as vinyl hydroxyl content or poly(vinyl alcohol) (“PVOH”) content). Residual hydroxyl content refers to the amount of hydroxyl groups remaining as side groups on121365P511 PC the chains of the polymer after processing is complete. For example, PVB can be manufactured by hydrolyzing poly(vinyl acetate) to poly(vinyl alcohol), and then reacting the poly(vinyl alcohol) with butyraldehyde to form PVB. In the process of hydrolyzing the poly(vinyl acetate), typically not all the acetate side groups are converted to hydroxyl groups. Further, the reaction with butyraldehyde typically will not result in all the hydroxyl groups being converted into acetal groups. Consequently, in any finished PVB, there will typically be residual acetate groups (such as vinyl acetate groups) and residual hydroxyl groups (such as vinyl hydroxyl groups) as side groups on the polymer chain. Generally, the residual hydroxyl content of a polymer can be regulated by controlling the reaction times and reactant concentrations, among other variables in the polymer manufacturing process. When utilized as a parameter herein, the residual hydroxyl content is measured on a wt. % basis per ASTM D-1396.

[0105] In various embodiments, the poly(vinyl butyral) resin may comprise about 8 to about 35 wt. % (wt. %) residual hydroxyl groups calculated as PVOH, about 13 to about 30 wt. % residual hydroxyl groups calculated as PVOH, about 8 to about 22 wt. % residual hydroxyl groups calculated as PVOH, or about 15 to about 22 wt. % residual hydroxyl groups calculated as PVOH; and for some of the high rigidity interlayers disclosed herein, for one or more of the layers, the poly(vinyl butyral) resin comprises greater than about 19 wt. % residual hydroxyl groups calculated as PVOH, greater than about 20 wt. % residual hydroxyl groups calculated as PVOH, greater than about 20.4 wt. % residual hydroxyl groups calculated as PVOH, and greater than about 21 wt. % residual hydroxyl groups calculated as PVOH.

[0106] In some embodiments, the poly(vinyl butyral) resin used in at least one polymer layer of an interlayer may include a poly(vinyl butyral) resin that has a residual hydroxyl content of at least about 18, at least about 18.5, at least about 18.7, at least about 19, at least about 19.5, at least about 20, at least about 20.5, at least about 21 , at least about 21.5, at least about 22, at least about 22.5 wt. % and / or not more than about 30, not more than about 29, not121365P511 PC more than about 28, not more than about 27, not more than about 26, not more than about 25, not more than about 24, not more than about 23, or not more than about 22 wt. %, measured as described above.

[0107] Additionally, one or more other polymer layers in the interlayers described herein may include another poly(vinyl butyral) resin that has a lower residual hydroxyl content. For example, in some embodiments, at least one polymer layer of the interlayer can include a poly(vinyl butyral) resin having a residual hydroxyl content of at least about 8, at least about 8.5, at least about 9, at least about 9.5, at least about 10, at least about 10.5, at least about 11 , at least about 11 .5, at least about 12, at least about 13 wt. % and / or not more than about 16, not more than about 15, not more than about 14, not more than about 13.5, not more than about 13, not more than about 12, or not more than about 11 .5 wt. %, measured as described above.

[0108] When the interlayer includes two or more polymer layers, the layers may include poly(vinyl butyral) resins that have substantially the same residual hydroxyl content, or the residual hydroxyl contents of the poly(vinyl butyral) resins in each layer may differ from each other. When two or more layers include poly(vinyl butyral) resins having substantially the same residual hydroxyl content, the difference between the residual hydroxyl contents of the poly(vinyl butyral) resins in each layer may be less than about 2, less than about 1 , or less than about 0.5 wt. %. As used herein, the terms “weight percent different” and “the difference between ... is at least ... weight percent” refer to a difference between two given weight percentages, calculated by subtracting one number from the other. For example, a poly(vinyl acetal) resin having a residual hydroxyl content of 12 wt. % has a residual hydroxyl content that is 2 wt. % different than a poly(vinyl acetal) resin having a residual hydroxyl content of 14 wt. % (14 wt. % - 12 wt. % = 2 wt. %). As used herein, the term “different” can refer to a value that is higher than or lower than another value. Unless otherwise specified, all “differences” herein refer to the numerical value of the difference and not to the specific sign of the value due to the order in which the numbers were subtracted. Accordingly, unless noted otherwise, all121365P511 PC“differences” herein refer to the absolute value of the difference between two numbers.

[0109] When two or more layers include poly(vinyl butyral) resins having different residual hydroxyl contents, the difference between the residual hydroxyl contents of the poly(vinyl butyral) resins can be at least about 2, at least about 3, at least about 4, at least about 5, at least about 6, at least about 7, at least about 8, at least about 9, at least about 10, at least about 12, at least about 15 wt. %, measured as described above.

[0110] The resin can also comprise less than 35 wt. % residual ester groups, less than 30 wt. %, less than 25 wt. %, less than 15 wt. %, less than 13 wt. %, less than 11 wt. %, less than 9 wt. %, less than 7 wt. %, less than 5 wt. %, or less than 1 wt. % residual ester groups calculated as polyvinyl ester, e.g., acetate, with the balance being an acetal, preferably butyraldehyde acetal, but optionally including other acetal groups in a minor amount, for example, a 2ethyl hexanal group (see, for example, U.S. Patent No. 5,137,954, the entire disclosure of which is incorporated herein by reference). The residual acetate content of a resin may also be determined according to ASTM D-1396.

[0111] In some embodiments, as described above, one or more of the polymer layers of the interlayer may be formed from PVB. Such PVB may have a residual acetate content of at least about 1 , at least about 3, at least about 5, at least about 7 wt. % and / or not more than about 15, not more than about 12, not more than about 10, not more than about 8 wt. %, measured as described above. When the interlayer comprises a multiple layer interlayer, two or more polymer layers can include resins having substantially the same residual acetate content, or one or more resins in various layers can have substantially different acetate contents. When the residual acetate contents of two or more resins are substantially the same, the difference in the residual acetate contents may be, for example, less than about 3, less than about 2, less than about 1 , or less than about 0.5 wt. %. In some embodiments, the difference in residual acetate content between two or more poly(vinyl butyral) resins in a multiple layer interlayer can be at least about 3, at least about 5, at least about 8, at121365P511 PC least about 15, at least about 20, or at least about 30 wt. %. When such resins are utilized in a multiple layer interlayer, the resins having different residual acetate contents may be located in adjacent polymer layers. When the multiple layer interlayer is a three-layer interlayer including a pair of outer “skin” layers surrounding, or sandwiching, an inner “core” layer, for example, the core layer may include a resin having higher or lower residual acetate content. At the same time, the resin in the inner core layer can have a residual hydroxyl content that is higher or lower than the residual hydroxyl content of the outer skin layer and fall within one or more of the ranges provided previously.

[0112] Poly(vinyl acetal) resins having higher or lower residual hydroxyl contents and / or residual acetate contents may also, when combined with at least one plasticizer, ultimately include different amounts of plasticizer. As a result, layers or domains formed of first and second poly(vinyl acetal) resins having different compositions may also have different properties within a single polymer layer or interlayer. Notably, for a given type of plasticizer, the compatibility of the plasticizer in the polymer is largely determined by the hydroxyl content of the polymer. Polymers with a greater residual hydroxyl content are typically correlated with reduced plasticizer compatibility or capacity. Conversely, polymers with a lower residual hydroxyl content typically will result in increased plasticizer compatibility or capacity. As a result, poly(vinyl acetal) resins with higher residual hydroxyl contents tend to be less plasticized and exhibit higher stiffness than similar resins having lower residual hydroxyl contents. Conversely, poly(vinyl acetal) resins having lower residual hydroxyl contents may tend to, when plasticized with a given plasticizer, incorporate higher amounts of plasticizer, which may result in a softer polymer layer that exhibits a lower glass transition temperature than a similar resin having a higher residual hydroxyl content. Depending on the specific resin and plasticizer, these trends could be reversed.

[0113] When two poly(vinyl acetal) resins having different levels of residual hydroxyl content are blended with a plasticizer, the plasticizer may partition between the polymer layers or domains, such that more plasticizer can be121365P511 PC present in the layer or domain having the lower residual hydroxyl content and less plasticizer may be present in the layer or domain having the higher residual hydroxyl content. Ultimately, a state of equilibrium is achieved between the two resins. Generally, this correlation between the residual hydroxyl content of a polymer and plasticizer compatibility / capacity can be manipulated and exploited to allow for addition of the proper amount of plasticizer to the polymer resin and to stably maintain differences in plasticizer content within multilayered interlayers. Such a correlation also helps to stably maintain the difference in plasticizer content between two or more resins when the plasticizer would otherwise migrate between the resins.

[0114] As a result of the migration of plasticizer within an interlayer, the glass transition temperatures of one or more polymer layers may be different when measured alone or as part of a multiple layer interlayer. In some embodiments, the interlayer can include at least one polymer layer having a glass transition temperature, outside of an interlayer, of at least about 33, at least about 34, at least about 35, at least about 36, at least about 37, at least about 38, at least about 39, at least about 40, at least about 41 , at least about 42, at least about 43, at least about 44, at least about 45, or at least about 46°C. In some embodiments, the same layer may have a glass transition temperature within the polymer layer of at least about 34, at least about 35, at least about 36, at least about 37, at least about 38, at least about 39, at least about 40, at least about 41 , at least about 42, at least about 43, at least about 44, at least about 45, at least about 46, or at least about 47°C.

[0115] In the same or other embodiments, at least one other polymer layer of the multiple layer interlayer can have a glass transition temperature less than 30°C and may, for example, have a glass transition temperature of not more than about 25, not more than about 20, not more than about 15, not more than about 10, not more than about 9, not more than about 8, not more than about 7, not more than about 6, not more than about 5, not more than about 4, not more than about 3, not more than about 2, not more than about 1 , not more than about 0, not more than about -1 , not more than about -2°C, or not more121365P511 PC than about -5°C, measured when the interlayer is not part of an interlayer. The same polymer layer may have a glass transition temperature of not more than about 25, not more than about 20, not more than about 15, not more than about 10, not more than about 9, not more than about 8, not more than about 7, not more than about 6, not more than about 5, not more than about 4, not more than about 3, not more than about 2, not more than about 1 , or not more than about 0°C, when measured outside of the interlayer.

[0116] According to some embodiments, the difference between the glass transition temperatures of two polymer layers, typically adjacent polymer layers within an interlayer, can be at least about 5, at least about 10, at least about 15, at least about 20, at least about 25, at least about 30, at least about 35, at least about 40, or at least about 45°C, while in other embodiments, two or more polymer layers can have a glass transition temperature within about 5, about 3, about 2, or about 1 °C of each other. Generally, the lower glass transition temperature layer has a lower stiffness than the higher glass transition temperature layer or layers in an interlayer and may be located between higher glass transition temperature polymer layers in the final interlayer construction.

[0117] For example, in some embodiments of this application, the increased acoustic attenuation properties of soft layers are combined with the mechanical strength of stiff / rigid layers to create a multilayered interlayer. In these embodiments, a central soft layer is sandwiched between two stiff / rigid outer layers. This configuration of (stiff) / / (soft) / / (stiff) creates a multilayered interlayer that is easily handled, can be used in conventional lamination methods and that can be constructed with layers that are relatively thin and light. The soft layer is generally characterized by a lower residual hydroxyl content (e.g., less than or equal to 16 wt. %, less than or equal to 15 wt. %, or less than or equal to 12 wt. % or any of the ranges disclosed above), a higher plasticizer content (e.g., greater than or equal to about 48 phr or greater than or equal to about 70 phr, or any of the ranges disclosed above) and / or a lower glass transition temperature (e.g., less than 30°C or less than 10°C, or any of the ranges disclosed above).121365P511 PC

[0118] It is contemplated that polymer interlayer sheets as described herein may be produced by any suitable process known to one of ordinary skill in the art of producing polymer interlayer sheets that are capable of being used in a multiple layer panel (such as a glass laminate). While all methods for the production of polymer interlayer sheets known to one of ordinary skill in the art are contemplated as possible methods for producing the polymer interlayer sheets described herein, this application will focus on polymer interlayer sheets produced through extrusion and / or co-extrusion processes. The final multiple layer glass panel laminates of the present disclosure are formed using processes known in the art.

[0119] In the extrusion process, thermoplastic resin, and plasticizers, including any of those resins and plasticizers described above, are generally pre-mixed and fed into an extruder device. Additives such as colorants and UV inhibitors (in liquid, powder, or pellet form) may be used and can be mixed into the thermoplastic resin or plasticizer prior to arriving in the extruder device. These additives are incorporated into the thermoplastic polymer resin, and by extension the resultant polymer interlayer sheet, to enhance certain properties of the polymer interlayer sheet and its performance in the final multiple layer glass panel product.

[0120] In the extruder device, the particles of the thermoplastic raw material and plasticizers, including any of those resins, plasticizers, and other additives described above, are further mixed and melted, resulting in a melt that is generally uniform in temperature and composition. Embodiments of the present invention may provide for the melt temperature to be approximately 200°C. Once the melt reaches the end of the extruder device, the melt is propelled into the extruder die. The extruder die is the component of the extruder device which gives the final polymer interlayer sheet product its profile. The die will generally have an opening, defined by a lip, that is substantially greater in one dimension than in a perpendicular dimension. Generally, the die is designed such that the melt evenly flows from a cylindrical profile coming out of the die and into the product’s end profile shape. A plurality of shapes can be imparted to the end121365P511 PC polymer interlayer sheet by the die so long as a continuous profile is present. Generally, in its most basic sense, extrusion is a process used to create objects of a fixed cross-sectional profile. This is accomplished by pushing or drawing a material through a die of the desired cross-section for the end product.

[0121] In some embodiments, a co-extrusion process may be utilized. Coextrusion is a process by which multiple layers of polymer material are extruded simultaneously. Generally, this type of extrusion utilizes two or more extruders to melt and deliver a steady volume throughput of different thermoplastic melts of different viscosities or other properties through a co-extrusion die into the desired final form. For example, the multiple layer interlayers of the present invention (e.g., in the form of a trilayer interlayer) may be preferably co-extruded using a multiple manifold co-extrusion device which includes a first die manifold, a second die manifold, and a third die manifold. The co-extrusion device may operate by simultaneously extruding polymer melts from each manifold through a die and out of an opening, where the multiple layer interlayer is extruded as a composite of three individual polymer layers. The polymer melts may flow through the die such that the core layer is positioned between the skin layers, to result in the manufacture of a trilayer interlayer with the core layer sandwiched between the skin layers. The die opening may include a pair of lips positioned on either side of the opening. Given the positional orientation of the polymer melts, the skin layers may come into contact with the lips. Regardless, the interlayer thickness can be varied by adjusting the distance between die lips located at the die opening.

[0122] The thickness of the multiple polymer layers leaving the extrusion die in the co-extrusion process can generally be controlled by adjustment of the relative speeds of the melt through the extrusion die and by the sizes of the individual die lips. According to some embodiments, the total thickness of the multiple layer interlayer can be at least about 13 mils, at least about 20, at least about 25, at least about 27, at least about 30, at least about 31 mils and / or not more than about 75, not more than about 70, not more than about 65, not more than about 60 mils, or it can be in the range of from about 13 to about 75 mils,121365P511 PC about 25 to about 70 mils, or about 30 to 60 mils. When the interlayer comprises two or more polymer layers, each of the layers can have a thickness of at least about 2, at least about 3, at least about 4, at least about 5, at least about 6, at least about 7, at least about 8, at least about 9, at least about 10 mils and / or not more than about 50, not more than about 40, not more than about 30, not more than about 20, not more than about 17, not more than about 15, not more than about 13, not more than about 12, not more than about 10, not more than about 9 mils. In some embodiments, each of the layers may have approximately the same thickness, while in other embodiments, one or more layers may have a different thickness than one or more other layers within the interlayer.

[0123] In some embodiments wherein the interlayer comprises at least three polymer layers, one or more of the inner layers can be relatively thin, as compared to the other outer layers. For example, in some embodiments wherein the multiple layer interlayer is a three-layer interlayer, the innermost layer can have a thickness of not more than about 12, not more than about 10, not more than about 9, not more than about 8, not more than about 7, not more than about 6, not more than about 5 mils, or it may have a thickness in the range of from about 2 to about 12 mils, about 3 to about 10 mils, or about 4 to about 9 mils. In the same or other embodiments, the thickness of each of the outer layers can be at least about 4, at least about 5, at least about 6, at least about 7 mils and / or not more than about 15, not more than about 13, not more than about 12, not more than about 10, not more than about 9, not more than about 8 mils, or can be in the range of from about 2 to about 15, about 3 to about 13, or about 4 to about 10 mils. When the interlayer includes two outer layers, these layers can have a combined thickness of at least about 9, at least about 13, at least about 15, at least about 16, at least about 18, at least about 20, at least about 23, at least about 25, at least about 26, at least about 28, or at least about 30 mils, and / or not more than about 73, not more than about 60, not more than about 50, not more than about 45, not more than about 40, not more than about 35 mils, or in the range of from about 9 to about 70 mils, about 13 to about 40 mils, or about 25 to about 35 mils.121365P511 PC

[0124] According to some embodiments, the ratio of the thickness of one of the outer layers to one of the inner layers in a multiple layer interlayer can be at least about 1.4:1 , at least about 1.5:1 , at least about 1.8:1 , at least about 2:1 , at least about 2.5:1 , at least about 2.75:1 , at least about 3:1 , at least about 3.25: 1 , at least about 3.5:1 , at least about 3.75: 1 , or at least about 4: 1 . When the interlayer is a three-layer interlayer having an inner core layer disposed between a pair of outer skin layers, the ratio of the thickness of one of the skin layers to the thickness of the core layer may fall within one or more of the ranges above. In some embodiments, the ratio of the combined thickness of the outer layers to the inner layer can be at least about 2.25:1 , at least about 2.4:1 , at least about 2.5: 1 , at least about 2.8:1 , at least about 3:1 , at least about 3.5:1 , at least about 4:1 , at least about 4.5: 1 , at least about 5:1 , at least about 5.5:1 , at least about 6:1 , at least about 6.5:1 , or at least about 7:1 and / or not more than about 30: 1 , not more than about 20: 1 , not more than about 15:1 , not more than about 10:1 , not more than about 9: 1 , or not more than about 8: 1 .Wedge

[0125] Multiple layer interlayers as described herein can comprise generally flat interlayers having substantially the same thickness along the length, or longest dimension, and / or width, or second longest dimension, of the sheet. In some embodiments, however, the multiple layer interlayers of the present invention can be tapered, or wedge-shaped, interlayers that comprise at least one tapered zone having a wedge-shaped profile. Tapered interlayers have a changing thickness profile along at least a portion of the length and / or width of the sheet, such that, for example, at least one edge of the interlayer has a thickness greater than the other. When the interlayer is a tapered interlayer, at least 1 , at least 2, at least 3, or more of the individual resin layers may include at least one tapered zone. Tapered interlayers may be particularly useful in, for example, heads-up display (HUD) panels in automotive and aircraft applications.121365P511 PC

[0126] The interlayers useful according to the invention are typically prepared by first contacting a single PVB layer as already described with the optical filters of the invention comprising a substrate and a mutlilayered stack. In use, this two-layer interlayer (optical filter plus PVB layer) may be combined with another PVB layer, advantageously a tapered, or wedge-shaped, interlayer that comprises at least one tapered zone having a wedge-shaped profile, to form an interlayer suitable for a head-up display. Alternatively, the other PVB layer may be substantially flat, or may also or alternatively be a multilayer interlayer, as already described, to improve acoustic functionality.

[0127] Thus, according to various aspects of the invention, interlayers as described herein may be used to form windshields that exhibit desirable acoustic properties, as indicated by, for example, the reduction in the transmission of sound as it passes through (i.e., the sound transmission loss of) the laminated panel. In certain embodiments, windshields formed with interlayers as described herein may exhibit a sound transmission loss at the coincident frequency, measured according to ASTM E90 at 20°C., of at least about 34, at least about 34.5, at least about 35, at least about 35.5, at least about 36, at least about 36.5, or at least about 37 dB or more.

[0128] The overall average thickness of the compound interlayer can be at least about 10, at least about 15, at least about 20, at least about 25, at least about 30, or at least about 35 mils and / or not more than about 100, not more than about 90, not more than about 75, not more than about 60, not more than about 50, not more than about 45, not more than about 40, not more than about 35, not more than about 32 mils, although other thicknesses may be used as desired, depending on the particular use and properties of the windshield and interlayer. If the interlayer is not laminated between two substrates, its average thickness can be determined by directly measuring the thickness of the interlayer using a caliper, or other equivalent device. If the interlayer is laminated between two substrates, its thickness can be determined by subtracting the combined thickness of the substrates from the total thickness of the multiple layer panel.121365P511 PC

[0129] Interlayers used to form windshields as described herein can be formed according to any suitable method. Exemplary methods of forming the flat or wedge polymer layers can include, but are not limited to, solution casting, compression molding, injection molding, melt extrusion, melt blowing, and combinations thereof. Multilayer interlayers including two or more polymer layers may also be produced according to any suitable method such as, for example, co-extrusion, blown film, melt blowing, dip coating, solution coating, blade, paddle, air-knife, printing, powder coating, spray coating, lamination, and combinations thereof.

[0130] When the wedge polymer layers formed by an extrusion or coextrusion process, one or more thermoplastic resins, plasticizers, and, optionally, one or more additives as described previously, can be pre-mixed, and fed into an extrusion device. The extrusion device can be configured to impart a particular profile shape to the thermoplastic composition in order to create an extruded sheet. The extruded sheet, which is at an elevated temperature and highly viscous throughout, can then be cooled to form a polymeric sheet. Once the sheet has been cooled and set, it may be cut and rolled for subsequent storage, transportation, and / or use as an interlayer.

[0131] Co-extrusion is a process by which multiple layers of polymer material are extruded simultaneously. Generally, this type of extrusion utilizes two or more extruders to melt and deliver a steady volume throughput of different thermoplastic melts of different viscosities or other properties through a co-extrusion die into the desired final form. The thickness of the multiple polymer layers leaving the extrusion die in the co-extrusion process can generally be controlled by adjustment of the relative speeds of the melt through the extrusion die and by the sizes of the individual extruders processing each molten thermoplastic resin material.

[0132] In certain embodiments, the wedge polymer layers used to form the compound interlayers as described herein may be produced such that the wedge polymer layer has a wedge angle profile that deviates from a predetermined, or prescribed, wedge angle profile for a target interlayer by no121365P511 PC more than 0.10, no more than 0.075, no more than 0.05 mrad, no more than 0.03, over at least about 50, at least about 60, at least about 70, at least about 80, or at least about 90 percent of the HUD region. In certain embodiments, the wedge angle profile of the wedge polymer layer may deviate from the predetermined wedge angle profile by no more than 0.10, no more than 0.075, no more than 0.05 mrad, no more than 0.03, over the entire region.

[0133] Methods of making such interlayers, or windshields including such interlayers, include the steps of obtaining prescribed wedge angle profiles for a target interlayer having a HUD region, and then forming an interlayer to have a similar wedge angle profile as the target interlayer. More particularly, the formation of the wedge polymer layer may be carried out such that the wedge angle profile varies from the prescribed wedge angle profile for the HUD region of the target interlayer by an amount within one or more of the above ranges. Such deviations can be determined by measuring the wedge angle of the formed interlayer.

[0134] Alternatively, or in addition, the thickness profile of the wedge polymer layer may also be measured, and the measured thickness profile may be compared to a target thickness profile at one or more points along the layer. In certain embodiments, the maximum difference between the measured thickness profile of a layer formed as described herein, and a predetermined target thickness profile may be not more than about 0.005, not more than about 0.0025, not more than about 0.0020, not more than 0.0015, or not more than about 0.0010 mm. Alternatively, or in addition, the difference between the measured thickness profile of a layer formed as described herein, and a predetermined target thickness profile can be at least about 0.025, at least about 0.05, or at least about 0.10 percent and / or not more than about 0.25, not more than about 0.20, not more than about 0.15, not more than 0.1 , or not more than about 0.05 percent, based on the target thickness at a given point.

[0135] The target wedge angle profile or target thickness profile may be provided by, for example, a third-party vendor, such as a laminator, a HUD system vendor, or a vehicle manufacturer, or it may be otherwise determined.121365P511 PCIn some embodiments, the measured wedge angle profile for a formed layer may vary slightly in shape from the target profile, but may still exhibit a maximum variation from the target wedge angle profile within the above ranges.

[0136] Windshields and other types of multiple layer panels may be formed from the compound interlayers and glazing panels as described herein by any suitable method. The typical glass lamination process comprises the following steps: (1 ) assembly of the two substrates and the interlayer; (2) heating the assembly via an IR radiant or convective device for a first, short period of time; (3) passing the assembly into a pressure nip roll for the first deairing; (4) heating the assembly for a short period of time to about 60°C. to about 120°C. to give the assembly enough temporary adhesion to seal the edge of the interlayer; (5) passing the assembly into a second pressure nip roll to further seal the edge of the interlayer and allow further handling; and (6) autoclaving the assembly at temperature between 90°C. and 150°C. and pressures between 150 psig and 200 psig for about 30 to 90 minutes. Other methods for de-airing the interlayer-glass interface, as described according to one embodiment in steps (2) through (5) above include vacuum bag and vacuum ring processes, and both may also be used to form windshields and other multiple layer panels as described herein.Wet coating

[0137] In an aspect, as disclosed in U.S. Pat. No. 6,455,141 , the optical filters of the invention may be combined with PVB using a PVB dissolved in a solution, which may be considered an intermediate, since a further PVB layer will typically be used on the other side of the optical filter and combined with two glass substrates to form a laminate. This intermediate includes the substrate and the multilayer stack, and a 5 mil (0.127 mm) or less, for example, coating of PVB, serving as adhesive, on at least one side of the optical filter, preferably on the side carrying the multilayer stack, where it provides a final product having greater stability and product life with improved corrosion resistance for the solar or energy reflective multilayer stack.121365P511 PC

[0138] In a further aspect the invention provides a method for producing this intermediate in which optical filter is coated (preferably over the energy reflective coating) with a solution of a PVB adhesive. Then the solvent is removed from the solution coating, leaving a layer of PVB on the energy- reflective layer carrying plastic film. The thickness of the coating of adhesive solution is predetermined to yield a final neat adhesive layer that may be, for example, less than 5 mils (0.127 mm) thick.

[0139] This process can be part of an overall laminated window production scheme in which the adhesive-coated, reflective layer-carrying plastic film is adhered and conformed to a smooth surface of a first sheet of glass, a second layer of PVB, for example a wedge-shaped PVB, is applied followed by a second sheet of glass and the overall structure is laminated.

[0140] In a further aspect, the interlayers of the invention may thus be used to form a laminated glass structure, which includes a first sheet of glass having a smooth first surface to which is adhered, a first PVB layer which may be 5 mils (0.127 mm) or less in thickness. The substrate of the optical filter is also adhered to the first PVB layer, either directly or through the multilayer stack. A second PVB layer bonds the optical filter to second sheet of glass.

[0141] In these aspects in which a PVB solution is used to apply the PVB to the optical filter, the first PVB adhesive layer, that is the layer which bonds the optical filter to the first glass sheet, may be less than 5 mils (0.127 mm) in thickness. It can be as thin as 0.25 mils (0.006 mm) or even thinner. Preferred thicknesses, based on performance and ease of reproducible preparation, are from 0.25 mils to 4 mils (0.006 mm to 0.102 mm) and especially 0.50 mils to 3.0 mils (0.013 mm to 0.076 mm) and more especially about 1 mil (0.025 mm).

[0142] The second PVB layer can be chosen from a wide range. It could, if desired, be as thin as the first layer but more commonly is thicker such as up to 300 mils (7.62 mm) for structured purposes and also to act as a leveling agent between the two sheets of glass which may not be identical in121365P511 PC contour. Thus the layer can be from 0.25 to 300 mils (0.006 mm to 7.62 mm) but is more commonly from 5 to 250 mils (0.127 mm to 6.35 mm) and especially 10 to 200 mils (0.254 mm to 5.08 mm). As noted, this second PVB layer may be flat, or wedge-shaped.

[0143] The PVB used in this aspect to be applied as a solution is selected based on its processing properties. In particular it should be capable of forming smooth coherent films of the desired, for example less than 5 mil (0.127 mm), thickness. It should also be soluble in volatile solvents to permit its application in accord with the preparative method taught herein.

[0144] In addition, it is generally preferred that the PVB adhesive be heat activated or heat curable, that is to be thermoplastic. This property comes into play in conventional laminated glass processes where heat and pressure are used to laminate the various layers into a final laminated glass product.

[0145] Poly(vinylbutyral) is a preferred material for forming the thin adhesive layer.

[0146] The thick, or second, PVB adhesive layer can be a preformed layer of poly(vinylbutyral), polyurethane, ethylene vinyl acetate polymers or the like. These materials are available in preformed sheets, generally with textured surfaces to allow for de-airing during lamination. Commercial materials have given good results.

[0147] Adhesive materials useful for the interlayers of the invention for use in glass lamination are substances that facilitate adhesion between the layers of glass and the interlayer material. Its primary function is typically to ensure that the glass layer construction remains bonded when impacted, providing structural integrity and safety elements. Adhesive materials also play a role in other properties of the combined structure (or laminate). This includes meeting requirements for mechanical properties, optical properties, acoustic properties, and ability in weathering. The adhesive properties of the materials used in glass laminates are typically “activated” during an industrial lamination process, with heat and pressure employed to ensure a strong,121365P511 PC durable bond between the glass panes and the interlayer. Adhesives useful according to the invention include PVB (Polyvinyl Butyral)s and other poly(vinyl acetal)s, TPU (Thermoplastic Polyurethanes), EVA (Ethylene-Vinyl Acetates), and ionomeric polymers.

[0148] Eastman’s Butvar™ brand PVB resin is a preferred adhesive for the thin layer and may include UV stabilizers or absorbers such as Ciba Geigy's Tinuvin 770 and 328 which can be added to the adhesive.

[0149] Preformed Saflex TG sheet is a preferred material for the thick adhesive layer.

[0150] The process used to produce these products involves applying the thin layer of PVB adhesive to the optical filters of the invention, laminating this adhesive-coated interlayer film to a first sheet of glass adding the thick adhesive layer and thereafter the second sheet of glass.

[0151] The layer of PVB adhesive needs to be applied with care. It needs to be a smooth consistent layer and very thin (particularly less than 5 mils (0.127 mm) in thickness). We have found that the easiest way to do this is to coat the surface of the sheet with a solution of the adhesive in a volatile solvent and then remove the solvent.

[0152] The solvent system used can be any material which dissolves or finely suspends the adhesive. In general, common organic solvents such as lower alcohols, ketones, esters, and the like can be used. One can consult the specification sheets for the particular adhesives employed to determine particular solvent systems to employ.

[0153] The PVB solution should ideally be applied in an amount which, after solvent removal, will provide the desired less than 5 mil (0.127 mm) thickness for the thin adhesive layer. This can be done empirically. For example, if a solution comprising 20% solution and 80% volatile solvent is applied one can estimate that the final film thickness will be about one fifth the depth of the solution applied.

[0154] The depth and smoothness of the adhesive solution can be controlled either by applying (such as by spraying or rolling) a solution which121365P511 PC is dilute enough to flow out to a smooth sheet and using an amount selected to give the desired depth. Alternatively, one can apply an excess of adhesive solution and level it to a desired depth with a doctor blade or the like. We have had satisfactory results using the simpler “spray and flow” method.

[0155] Solvent removal can be accomplished with or without heating or air movement. In most industrial settings it is desired to capture the volatile solvents as they evaporate so often a heated forced air source is employed together with a solvent recovery system on the exhaust.Window films

[0156] In an aspect, the optical filters of the invention may be in the form of a window film that includes a hardcoat material, typically applied as a wet coating, the substrate such as polyethylene terephthalate film as already described, the sputtered stack comprising the alternating layers as already described, optionally a laminating adhesive and another PET film layer, a mounting adhesive, and a release film. The hardcoat material provides a protective coating for the electromagnetic blocking film. The hardcoat layer may, for example, be an epoxy, resin, or any natural or synthetic material which provides adequate protection to the other layers of the optical filter depending on the application for which it is used. The hardcoat material should be transparent to visible light. A suitable hardcoat composition includes the hardcoat described in US Pat No. 4,557,980, which is hereby incorporated by reference.

[0157] The PET film may comprise any suitable polyethylene terephthalate film commercially available providing that its transparency and haze levels are suitable for the application. Other transparent polymeric (or non- polymeric) films may be suitable as well such as polycarbonate, polyethylene naphthalate, etc. The PET film should be substantially transparent to visible light. Suitable PET films may include DuPont or equivalent available from DuPont Teijin Films with a thickness of approximately 1 / 2 mil or 12.5 microns to 10 mils or 250 microns. The sputtered stack comprises the alternating layers121365P511 PC as described herein. The laminating adhesive may be any adhesive that permits substantial transmission of visible light. When two PET films are used, they may be identical or different.

[0158] Additionally or optionally, the PET films may have UV absorbers and / or dyes, nanoparticles or pigments either coated onto one or both of its surfaces or have them contained in the film itself. The mounting adhesive may be any suitable adhesive that will permit substantial transmission of visible light when applied. The mounting adhesive may include, for example, a pressure sensitive adhesive such as National Starch 80-1057 or the like and may be applied at approximately 3.5 - 12.0 pounds / ream coat weight. The release film may be any material that removably separates from the mounting adhesive layer. The release film protects the mounting adhesive until the time of installation. At such point, the release film is removed, thereby exposing the mounting adhesive 360 so that the mounting adhesive may contact the surface to which the electromagnetic blocking film is to be applied.

[0159] Suitable sputtered stacks may be manufactured using a vacuum deposition known in the art as sputtering. However, other methods of manufacture can also be employed, including, for example, vapor deposition or wet coating.

[0160] As noted, the silver layers may be 5% gold alloyed silver layers, and the various metal layers may be applied by sputtering or chemical vapor deposition (CVD). It should be appreciated, however, that a variety of other IR reflecting metals, alloys or combinations thereof, including, for example, gold, palladium, copper, etc. are known in the field of window film and IR reflecting may be employed alternatively in the present invention instead of pure silver. Other metal oxides or dielectrics could be used in place of the Indium oxide. Similarly, the particular thickness of the particular film stack layers may be modified according to simple trial and error measurements as needed to achieve desired performance and color uniformity criteria.

[0161] The window films just described may be installed on an existing window, such that the installed solar control film may include a hardcoat121365P511 PC material, a Polyethylene Terephthalate (PET) film, a sputtered stack, a laminating adhesive, a PET film layer, a mounting adhesive, attached to a window. The window is preferably glass, but may be plastic or any other transparent or translucent material. In an embodiment, a dual-layer solar control film may be formed. This embodiment may include a hardcoat material, a PET film, a sputtered stack, a laminating adhesive, a sputtered stack, a PET film, a mounting adhesive, and a release film. The two sputtered stacks, may be of the kind already described.

[0162] In another aspect of the present invention, a visible light transparent solar control window film may be retrofitted onto glass or plastic windows. The solar control film can be employed in a variety of ways. The solar control film may be applied to existing windows as part of a retrofit. The solar control film may be applied to newly manufactured glass or plastic panes. The solar control film may be wholly incorporated as part of the original manufacturing process of the glass or plastic window panes. In other variations, the solar control film may be suspended in between glass panes or used as a hanging shade material.

[0163] It should be appreciated that the various embodiments of the present invention may be configured as known in the field of architectural and structural design. For example a laminated glass having two layers of glass and sandwiching the solar control film. Of course it is understood that the exact arrangement of layers need not be arranged exactly as described, but may be arranged according to the desired use or particular needs of any given application. Such arrangements may include, for example, additional layers (glass, plastic or film), the elimination of particular layers, or the alteration of the order in which the layers are combined. The films can be put, for example, anywhere on one or more of the surfaces of glass or other glazing to get the same or similar effects. One will recognize that numerous combinations of coated glazing materials and films may be used to achieve the same or similar result. It is also understood that the present invention may employ sputtered glass, various glazing materials, plastic films or any combination of these or121365P511 PC other materials. Moreover, the term “film” can be one or more layers added to glass by any process. Films or layers may be laminated to polyvinyl butyral (PVB) or other material such as polyurethane (PUR) that sticks to the glass or glazing material. A sputtered film or layer may be laminated between PVB sheets or other materials that stick to the glazing and then laminated to or between glass sheets or other glazing. Layers may be deposited directly on glass or plastic glazing by any means appropriate. Alternatively, low emission glass may be used in combination with an attenuating film on the other glass or glazing surfaces. Ultraviolet light blocking materials may also be employed in the stacks, layers, and films of the present invention.

[0164] Other embodiments of the present invention permit the creation of windows that incorporate or integrate optical filter films prior to their installation. Such films may be applied to a window’s exterior facing surface, interior facing surface, both the exterior or interior surfaces, suspended between the panes or be embedded within one or more window panes. The film may also be employed in a drawn shade, curtain or blinds.

[0165] As described the optical filters of the invention may include two alternating layer pairs having a dielectric spacer layer and a metal layer. The optical filters may be in the form of films that include three layer pairs, the layer pair including a dielectric or metal oxide layer and a metal layer. The electromagnetic blocking filter may further include at least one additional dielectric or metal oxide layer to protect the last metal layer, that is one or more boundary layers. Optionally, the filter may include a flexible transparent sheet configured for attachment to a glazing of a window. For example, the filter further may include a safety film adhered to the glazing. Optionally, the filter may include a first and a second filter portion (such as a two separated dielectric / metal stacks, with these first and second filter portions being spaced apart from each other).

[0166] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the specification and claims are to be understood as being121365P511 PC modified in all instances by the term "about.” Unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, each numerical parameter should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Further, the ranges stated in this disclosure and the claims are intended to include the entire range specifically and not just the endpoint(s). For example, a range stated to be 0 to 10 is intended to disclose all whole numbers between 0 and 10 such as, for example 1 , 2, 3, 4, etc., all fractional numbers between 0 and 10, for example 1.5, 2.3, 4.57, 6.1113, etc., and the endpoints 0 and 10. Also, a range associated with chemical substituent groups such as, for example, “C1 to C5 diols”, is intended to specifically include and disclose C1 , C2, C3, C4 and C5 diols.

[0167] 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 reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in its respective testing measurements.

[0168] As used in the specification and the appended claims, the singular forms "a," "an" and "the" include their plural referents unless the context clearly dictates otherwise. For example, a reference to a “polyester,” a "dicarboxylic acid”, a "residue” is synonymous with “at least one” or “one or more” polyesters, dicarboxylic acids, or residues and is thus intended to refer to both a single or plurality of polyesters, dicarboxylic acids, or residues. In addition, references to a composition “comprising”, “containing”, “having” or “including” "an" ingredient or "a" polyester is intended to include other ingredients or other polyesters, respectively, in addition to the specifically identified ingredient or residue. Accordingly, the terms "containing", “having” or “including” are intended to be synonymous and may be used interchangeably121365P511 PC with the term "comprising", meaning that at least the named compound, element, particle, or method step, etc., is present in the composition or article or method, but does not exclude the presence of other compounds, catalysts, materials, particles, method steps, etc., even if the other such compounds, material, particles, method steps, etc., have the same function as what is named, unless expressly excluded in the claims.

[0169] Also, it is to be understood that the mention of one or more process steps does not preclude the presence of additional process steps before or after the combined recited steps or intervening process steps between those steps expressly identified. Moreover, the lettering of process steps or ingredients is a convenient means for identifying discrete activities or ingredients and the recited lettering can be arranged in any sequence, unless otherwise indicated.

[0170] While the composition of the present invention has been described above in detail with respect to two exemplary embodiments with two end-use utilities, it will be understood by the person of ordinary skill that the composition of the present invention may be utilized in a wide variety of enduse applications.

[0171] The following examples set forth suitable and / or preferred methods and results in accordance with the invention. It is to be understood, however, that these examples are provided by way of illustration and nothing therein should be taken as a limitation upon the overall scope of the invention. All percentages are by weight unless otherwise specified.EXAMPLES

[0172] All Samples were prepared in a roll-to-roll vacuum coater. A PET substate was loaded into the coater and metal and metal oxide layers were deposited from blocks of the desired material (sputtering targets) by a magnetron sputtering process.

[0173] Infrared-reflective solar control films were constructed with the following functional components. The substrate was a base film on which the121365P511 PC other layers were deposited. The substrate used was a special automotive grade PET film, either 0X50, having a 2m il thickness, XG6SF1 , having a 3 mil thickness, or Lumirror 41 .31 , Toray Films Europe, having a 3 mil thickness, as indicated in the tables.

[0174] The reflective metal layer (ME) used was silver . The dielectric layer (DE) of the dielectric spacer layer was indium oxide. The seed layers (Seed) used were zinc aluminum oxide.

[0175] The cap layers (Cap) used were either titanium dioxide, applied as a metal layer that oxidizes during deposition, or zinc aluminum oxide. Examples 1-13 and 16a and 16b used titanium dioxide, while examples 14 and 15 used zinc aluminum oxide.

[0176] During the deposition, the layers were deposited in several coating passes. During each pass, a group of layers was deposited (depending on the machine setup) and each layer thickness was controlled with an inline spectrophotometric monitor. The target values of the thickness were derived from the corresponding optical model of each variant.

[0177] After vacuum coating, the film was further processed. All samples were prepared as laminated interlayer samples for automotive glazing applications. To achieve this, the film was placed into a stack of glass and PVB. This package was then laminated in an autoclave, wherein the PVB acts as an adhesive that combines all layers to a single laminated glass unit. The PVB used was either a clear variant or a color variant (pigmented) component.

[0178] Lamination Option 1 : Interior Glass | PVB clear | SC-Film | PVB clear | Glass | ExteriorLamination Option 2: Interior Glass | PVB colored | SC-Film | PVB clear | Glass | Exterior

[0179] Tables 1a and 1 b show the thicknesses of each of the layers of each example, thus giving the structure of each of the optical filters (SC option 1 , 2, or 3), as well as the substrate used. These tables also indicate the lamination option, either 1 or 2, as referenced above.121365P511 PC

[0180] Table 2 shows the same stacks, in terms of thickness of the dielectric spacer layers (dielectric layer, plus seed and cap when present) and the metal layers.

[0181] Table 3 provides the following measured values: VLR at the indicated angles; VLT; TTS; IRER; VLT / TTS; IRER / VLR; and IRER x VLR.

[0182] Tables 4a and 4b show the reflected color coordinates (L* a* and b*) at the indicated angles, and maximum a* and b* differences.

[0183] Tables 5 show AC* values for each of the examples, referenced to the color coordinates at the angles indicated.

[0184] Tables 6 show AE values for each of the examples, referenced to the color coordinates at the angles indicated.Additional Disclosure

[0185] In any of the proceeding embodiments disclosed herein, the haze of the optical filter, interlayer, or laminate can be less than 8.0 7.5, 7.0, 6.5, 6.0, 5.5, 5.0, 4.5, 4.0, 3.5, 3.0, 2.5, 2.0, 1 .5, 1 .0, or 0.5 measured according to ASTM-D1103.

[0186] In another embodiment of the invention, a laminate is provided comprising the optical filter in any of the previously disclosed embodiments; wherein the laminate has a haze measurement of less than 8.0, 7.5, 7.0, 6.5, 6.0, 5.5, 5.0, 4.5, 4.0, 3.5, 3.0, 2.5, 2.0, 1 .5, 1 .0, or 0.5 according to ASTM- D1103.

[0187] In another embodiment of the invention, a laminate is provided comprising the interlayer in any of the previously disclosed embodiments; wherein the laminate has a haze measurement of less than 8.0, 7.5, 7.0, 6.5, 6.0, 5.5, 5.0, 4.5, 4.0, 3.5, 3.0, 2.5, 2.0, 1 .5, 1 .0, or 0.5 according to ASTM- D1103.

[0188] In another embodiment of the invention, a laminate glazing is provided according any of the previous disclosed embodiments; wherein the laminate glazing has a haze measurement of less than 8.0, 7.5, 7.0, 6.5, 6.0,121365P511 PC5.5, 5.0, 4.5, 4.0, 3.5, 3.0, 2.5, 2.0, 1.5, 1.0, or 0.5 according to ASTM- D1103.

[0189] Haze is measured by a haze-meter such as the Haze-guard from BYK-Gardner Instruments, according to ASTM D-1003.Table 1a.Table 1b.Table 2.Table 3.Table 4a.Table 4b.Table 5.CD

Claims

CLAIMSWe claim:1 . An optical filter, exhibiting one or more of the following properties: a visible light reflection (VLR) value within the visible spectrum of at least 12% VLR; a visible light transmission (VLT) value within the visible spectrum of no more than 60% VLT; a maximum difference in a* values at 30°, 45°, 60°, and 75° that is no higher than 6 units; or a maximum difference in b* values at 30°, 45°, 60°, and 75° that is no higher than 12 units.

2. An optical filter, exhibiting a consistent reflective color at varying viewing angles, characterized by one or more of : an a* at 30°, 45°, 60°, and 75° that is from about -10 to about 10, or from -10 to 0, or from -8 to 0, or from -7 to -1 ; or a maximum difference in a* values at 30°, 45°, 60°, and 75° that is no higher than 10 units, or no higher than 9, or no higher than 8, or no higher than 7, or no higher than 6, or no higher than 5, or no higher than 4, 3, 2 units, or 1 unit; or from 0 to 5 units, or less than 0.9, 0.8, 0.7, or 0.5 units; or a b* at 30°, 45°, 60°, and 75° that is from about -10 to about 20, or from -9 to 15, or from -8 to 12, or from -7 to 10; or a maximum difference in b* values at 30°, 45°, 60°, and 75° that is no higher than 15 units, or no higher than 12, or no higher than 10, or no higher than 8, or no higher than 7, or 6, or 5, or 4, or 2 units or even 1 unit, or less than 0.9, 0.8, 0.7, 0.6, or 0.5 units.

3. The optical filter of any of the preceding claims, wherein the optical filters exhibit a AE of no more than 25, or no more than 20, or no more than 15, or no more than 12, or no more than 10, or no more than 9, or no more than 8, or no more than 7, or no more than 6, or no more than 5, or no more than 4, or nomore than 3, or no more than 2, or no more than 1 , or no more than 0.5, when comparing the reflective L*a*b* color coordinates measured at a chosen first angle of 0°, 30°, and 45° to the reflective L*a*b* color coordinates measured at a chosen second angle of 0°, 30°, 45°, 60°, and 75°.

4. The optical filter of any of the preceding claims, wherein the optical filters exhibit a AC* of no more than 15, or no more than 14, or no more than 13, or no more than 12, or no more than 11 , or no more than 10, or no more than 9, or no more than 8, or no more than 7, or no more than 6, or no more than 5, or no more than 4, or no more than 3, or no more than 2, or no more than 1 , or no more than 0.5, when comparing the reflective L*a*b* color coordinates measured at a chosen first angle of 0°, 30°, and 45° to the reflective L*a*b* color coordinates measured at a chosen second angle of 0°, 30°, 45°, 60°, and 75°.

5. The optical filter of any of the preceding claims, wherein the optical filter exhibits a VLT / TTS value from about 0.5 to about 2.5, or from 0.7 to 2.3, or from 1 to 2.0, or at least 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 , 1.2, 1 .3, 1 .4, or at least 1 .5, up to about 2.5, 2.4, 2.3, 2.2, 2.1 , 2.0, 1.9, 1.8, 1.7, 1.6, 1.5, or 1.4.

6. The optical filter of any of the preceding claims, wherein the optical filter exhibits a VLT of no more than 60%, and an IRER / VLR value from about 1 to about 6, or from 1 .2 to 5, or from 1 .5 to 4.5, or at least 1 , 1.1 , 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.8, or 2,0, up to about 4, 4.1 , 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.1 , 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, or up to 6.

7. The optical filter of any of the preceding claims, wherein the optical layers of the invention exhibit a VLT of at least 60%, and an IRER / VLR value from about 6 to about 10, or from 6.5 to 9, or from 7 to 8, or at least 6, 6.1 , 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, or 7.0, up to 7.1 , 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1 , 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, or up to 9.

8. The optical filter of any of the preceding claims, wherein the optical filter exhibits a VLT of no more than 60%, an IRER x VLR from about 1000 to about 6000, or from 1100 to 5800, or from 1200 to 5500, or at least 1000, 1100, 1200, 1300,1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000, 3100, 3200, 3300, 3400, 3500, up to about 4000, 4100, 4200, 4300, 4400, 4500, 4600, 4700, 4800, 4900, 5000, 5500, or up to 6000.

9. The optical filter of any of the preceding claims, wherein the optical filter exhibits a VLT of from about 2% to about 60%, or from 5% to 50%, or from 8% to about or at least 2, 3, 5, 7, 9, 10, 12, 15, 18, 20, 25, 28, 32, 33, 34, 35, 36, 37, 38, 39, or 40%, up to 50, 55, 58, 60, 65, 68, or 70%10. The optical filter of any of the preceding claims, wherein the optical filter exhibits a VLT from about 50% to about 85%, or from 60% to 82%, or from 70% to 80%, or at least 50, at least 52, 53, 55, 57, 59, 60, 62, 65, 66, 67, 68, 69, or at least 70%, 71 , 72, 73, 74, 75, 76, 77, 79, or at least 80%, up to 88, 87, 86, 85, 84, 83, 82, 81 , or up to 80%, 79, 78, 77, 76, or up to 75%.

11. A window film comprising the optical filter of any of the preceding claims and a mounting adhesive.

12. The optical filter of any of the preceding claims, wherein the dielectric spacer comprises a seed layer, a dielectric layer, and a cap layer, in that order.

13. The optical filter of any of the preceding claims, wherein the seed layer of the dielectric spacer layer has a thickness from about 5 to about 25nm, or from 7 to 20nm , or from 10 to 20nm .

14. The optical filter of any of the preceding claims, wherein the cap layer of the dielectric spacer layer has a thickness from about 3nm to about 10nm, or from 4nm to 8nm, or from 5 to 7nm.

15. The optical filter of any of the preceding claims, wherein the dielectric spacer comprises a metal oxide.

16. An interlayer, comprising: a. the optical filter of any of the preceding claims; and b. at least a first layer of an adhesive material, adjacent the optical filter.

17. The interlayer of any of the preceding claims, wherein the adhesive material comprises one or more of: a poly(vinyl butyral).

18. The interlayer of any of the preceding claims, wherein the first layer of an adhesive material is in the form of a wedge.

19. The interlayer of any of the preceding claims, further comprising a second layer of an adhesive material, in the form of a wedge.

20. The interlayer of any of the preceding claims, wherein the first layer of an adhesive material and the second layer of an adhesive material have a difference in Tg of at least 5°C, or at least 10°C, or at least 12°C.21 . The interlayer of any of the preceding claims, wherein the interlayer further comprises a holographic optical element.

22. The interlayer of any of the preceding claims, wherein the interlayer is provided with a cutout which allows electromagnetic waves to pass through it.

23. A laminated glazing comprising: a. the interlayer of any of the preceding claims; and b. a first rigid substrate, on a first side of the interlayer; and c. a second rigid substrate on a second side of the interlayer.

24. A method of using the window film of any of the preceding claims, comprising applying the window film to a window that extends from the viewing area of a windshield to above a driver of a car.

25. The laminated glazing of any of the preceding claims, wherein the optical filter is electrically resistive such that a temperature of the optical filter increases on application of an electrical current.

26. The laminated glazing of any of the preceding claims, wherein the optical filter is an antenna.

27. The optical filter of any of the preceding claims, wherein at least one of the dielectric spacer layers and the metal layers are applied by one or more of reactive sputtering, chemical vapor deposition, or physical vapor deposition.

28. A sunroof comprising the optical filter of any of the preceding claims.

29. An architectural glazing comprising the optical filter of any of the preceding claims.

30. A laminate glazing according to any of the Claims 23-25 and 26; wherein the laminate glazing has a haze measurement of less than 8.0, 7.5, 7.0, 6.5, 6.0, 5.5, 5.0, 4.5, 4.0, 3.5, 3.0, 2.5, 2.0, 1.5, 1.0, or 0.5 measured according to ASTM-D1103.

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